Patent Publication Number: US-2023132592-A1

Title: Power supply unit, emitting apparatus including the same, and control method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of International Application No. PCT/CN2021/114304, filed Aug. 24, 2021. This patent application claims foreign priority to Chinese Patent Application No. 202010858924.0, filed Aug. 24, 2020 and Chinese Patent Application No. 202010857698.4, filed on Aug. 24, 2020. Herein which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to the field of lidar technologies, and in particular, to a power supply unit for a laser emitter, an emitting apparatus including the same, and a method for controlling a laser emitter to emit light by using the same. 
     BACKGROUND OF THE INVENTION 
     In a lidar emitting system, a manner of a common anode is usually used to drive laser emitters. For example, as shown in  FIG.  1 A , in the lidar emitting system in the prior art, a plurality of laser emitters LAS 1 -LASN share a common power supply HV that supplies power continuously. A cathode of each laser emitter is respectively connected to a switching device (J 1 -JN as shown in the figure), and light emission of the laser emitter is determined by activating of the switching device. Ideally, each laser emitter is equipped with a discharge capacitor (C 1 -CN as shown in the figure). Limited by the sizes of the switching device and the capacitor in the prior art, the plurality of laser emitters cannot be arranged more densely, which limits vertical resolution of the lidar. 
       FIG.  1 B  shows a power supply and a driving circuit of a single laser emitter LAS 1 . The switching device used in the driving circuit is GaN. A specific operating process is as follows: When a high-side switch is closed (conducted), the power supply HV charges a capacitor C; after a period of time, the high-side switch is disconnected (power cannot be turned on, and a charging loop of the capacitor C is disconnected). After a driving signal for the GaN switch is sufficient to open the GaN switch, a discharging loop is formed between the capacitor C, the laser emitter LAS 1 , the GaN switch and the ground, which makes the laser emitter LAS 1  emit light. 
       FIG.  2 A  shows a relative arrangement relationship of a plurality of laser emitters, GaN switching devices, and capacitors on a printed circuit board (PCB). As shown in  FIG.  2 A , due to the limitation of the GaN switching size and the capacitor size (The GaN switch and the capacitor are relatively large. For example, in an actual packaging process, when selecting discharge capacitor, it is necessary to consider parameters such as capacitance value and capacitance withstand voltage, so the available capacitance is 0402 (EIA nominal), and its size is 1000 um*500 um, in addition, considering an SMT (surface mounting technology) process, the packaging size is generally recommended to be 1400 um*900 um; When selecting GaN switching device, considering the withstand voltage and co-current capability, the minimum size that can be achieved by the conventional process is about 680 um*680 um, and considering the SMT process, the packaging size is generally recommended to be 800 um*800 um.), the capacitor and the GaN switch can only be arranged separately on both sides of the laser emitter. And in order to meet the requirement of one GaN switch driving one laser emitter (that is, a ratio of a quantity of the laser emitters to a quantity of the GaN switching devices is 1:1), the GaN switches also need to be arranged in two rows and staggered. 
     The arrangement of  FIG.  2 A  is simplified as shown in  FIG.  2 B . Referring to  FIG.  2 A  and  FIG.  2 B , it can be seen that a distance between the laser emitter LAS 2  and the corresponding GaN switch is greater than a distance between the laser emitter LAS 1  and the corresponding GaN switch. Staggered placement of the GaN switches leads to different lengths of discharging loops between every two laser emitters (such as LAS 1  and LAS 2 ), which may result in different emission power between every two laser emitters. There is a certain distance between the GaN switch and the laser emitter, which also affects a response speed of the laser emitter. 
     The lidars used for unmanned vehicles, logistics vehicles, and sweeping robots are usually multi-line radars, which means that the emitting system has a plurality of laser emitters. If the laser emitters are arranged according to the relative relationship shown in  FIG.  2 A  and  FIG.  2 B , the distance between laser emitter and its corresponding GaN switch is relatively inconsistent with each other, resulting in different parameters such as detection accuracy of each channel or line, which is not conducive to the consistency of detection, further affecting overall performance of the lidar. 
     In addition, as shown in  FIG.  1 A , the power supply HV supplies power to the line at a fixed value (for example, HV=20 V) and cannot be adjusted quickly. The reason is that if an adjustment speed of the power supply is excessively fast, various capacitance and inductance effects on the line accumulate and the adjustment speed will not be changed as expected. In addition, since the current high-voltage power supply usually uses a DC-DC power supply or a low dropout regulator (LDO) with a slow switching speed, which also leads to light intensity of the laser emitter failing to be adjusted quickly. However, an external environment faced by the lidar is changeable. If a same fixed light intensity is used for detection, due to the difference in reflectivity of an external targets, it is easy to cause a detector to saturate or fail to detect signal, which cannot meet the needs of various scenarios. Detection indicators, such as a detection distances, of each lines of the lidar may also be different, and there is also a need for adjustment. 
     The content of the background is merely technologies known to the public, and does not represent conventional technologies in the field. 
     BRIEF SUMMARY OF THE INVENTION 
     To resolve the problem in the prior art that an adjustment of bus voltage is slow and cannot be changed as expected, that is, high-speed change cannot be achieved, which further causes that light intensity of a laser emitter cannot be adjusted quickly, the present disclosure further provides a power supply unit for a laser emitter, including: 
     a preparatory voltage source, configured to output a preparatory voltage; 
     a high-voltage generation unit, coupled to the preparatory voltage source, configured to receive the preparatory voltage, generate an output voltage higher than the preparatory voltage, and output the output voltage via an output end; and 
     a capacitor unit, coupled to the output end of the high-voltage generation unit, 
     where the high-voltage generation unit and the capacitor unit are configured to cooperatively adjust the output voltage through charge and discharge processes. 
     According to an aspect of the present disclosure, the high-voltage generation unit includes: 
     a first inductor, a first end of which is coupled to the preparatory voltage source, configured to receive electrical energy from the preparatory voltage source; 
     a first switch having a first end coupled to a second end of the first inductor and a second end connected to ground, the first switch configured to, upon switching to a connected state, connect the voltage source and the first inductor to form a charging loop, and cause the first inductor to be charged; and 
     a second switch having a first end coupled to the second end of the first inductor and a second end coupled to the capacitor unit as the output end of the high-voltage generation unit. 
     According to an aspect of the present disclosure, the power supply unit further includes a reset switch, where the reset switch is connected between the preparatory voltage source and the capacitor unit and configured to reduce the output voltage back to the preparatory voltage. 
     According to an aspect of the present disclosure, the first switch, the second switch, and the reset switch include one or more of a GaN switch and a CMOS switch. 
     The present disclosure further provides an emitting apparatus for a lidar, including: 
     a plurality of power supply units as described above, configured to convert preparatory voltages into high voltages to output; 
     a laser emitter unit, including a plurality of laser emitters, where one end of each laser emitter is connected to an output end of one of the power supply units, so that at least two laser emitters are connected to the output ends of different power supply units; and 
     at least one switching device, where cathodes of laser emitters that do not share a common high voltage are connected to one of the at least one switching devices, and the one of the at least one switching device is configured to selectively control a connection state of a current loop formed by one of the high voltages, the laser emitters connected thereto, and the ground. 
     The present disclosure further provides a control unit for controlling the power supply unit as described above, where the high-voltage generation unit includes a first switch, a second switch, and a reset switch, and the control unit includes: 
     generating a voltage control signal according to a time sequence of emission of a laser emitter, and outputting the voltage control signal to control electrodes of the first switch, the second switch, and the reset switch respectively, to control the high-voltage generation unit to output an output voltage higher than the preparatory voltage, and control the capacitor unit and the high-voltage generation unit to cooperatively adjust the output voltage through charge and discharge processes. 
     The present disclosure further provides a method for controlling a laser emitter to emit light by using the power supply unit as described above, including: 
     outputting the preparatory voltage by the preparatory voltage source; 
     generating the output voltage higher than the preparatory voltage through the high-voltage generation unit; and 
     cooperatively adjusting the output voltage through charge and discharge processes of a capacitor unit and the high-voltage generation unit. 
     According to an aspect of the present disclosure, the high-voltage generation unit includes: a first inductor, a first end of which is coupled to the preparatory voltage source, a first switch having a first end coupled to a second end of the first inductor and a second end connected to ground, and a second switch having a first end coupled to the second end of the first inductor and a second end coupled to the capacitor unit, and the method further includes: 
     receiving electrical energy from the preparatory voltage source through the first inductor; 
     causing the preparatory voltage source and the first inductor to form a charging loop by closing the first switch and opening the second switch, thus charging the first inductor by the preparatory voltage source; and 
     causing the preparatory voltage source and the first inductor to form a discharging loop by opening the first switch and closing the second switch, thus charging the capacitor unit by the preparatory voltage source and the first inductor which causes the output voltage to be higher than the preparatory voltage. 
     According to an aspect of the present disclosure, the method further includes: 
     by opening the first switch and closing the second switch, causing the capacitor unit to discharge, and causing the first inductor to receive electrical energy from the capacitor unit, which reduces the output voltage. 
     According to an aspect of the present disclosure, the power supply unit further includes a reset switch, the reset switch is connected between the preparatory voltage source and the capacitor unit, and the method further includes: 
     reducing the output voltage back to the preparatory voltage through the reset switch. 
     The present disclosure provides an emitting apparatus for a lidar, including: 
     a plurality of power supply units, configured to receive a preparatory voltage and output a high voltage, and at least two power supply units output the high voltage at different times respectively, where the high voltage is a voltage higher than the preparatory voltage; 
     a laser emitter unit, including a plurality of laser emitters, where an anode of each laser emitter is connected to an output end of the power supply unit, which causes at least two of the laser emitters to be connected to different power supply units; and 
     at least one switching device, where cathodes of a subnet of laser emitters that do not share the common high voltage are connected to one of the switching devices, and the switching device is configured to control a connection state of a current loop formed by the corresponding power supply unit, the laser emitter connected thereto, and the ground. 
     The present disclosure further provides a method for controlling the emitting apparatus as described above to emit light, including: 
     controlling a power supply unit to output a voltage; and 
     controlling a current loop of a subset of laser emitters to be connected through the switching device, which causes a laser emitter connected to the power supply unit of the output voltage to emit light by the effect of the voltage. 
     The present disclosure further provides a lidar, including the emitting apparatus as described above, a receiving apparatus, and a control apparatus, where 
     the emitting apparatus is suitable for driving laser emitters to emit a detection laser beam according to a certain time sequence under the control of the control apparatus; 
     the receiving apparatus is suitable for receiving an echo reflected by an external obstacle relative to the lidar; and 
     the control apparatus is suitable for generating a voltage control signal according to a detection demand of the lidar, controlling a power supply unit to output a voltage, and generating a driving signal to activate a subnet of the laser emitters to emit light; and is suitable for processing the echo received by the receiving apparatus, and calculating a distance and/or reflectivity between the external obstacle and the lidar according to the echo signal. 
     An exemplary embodiment of the present disclosure provides an emitting apparatus for a lidar. A plurality of power supply units that share a preparatory voltage source are used to activate laser emitters connected to the power supply units to emit light, a plurality of laser emitters that do not share a voltage can be individually and one by one activated for a certain laser emitter or a certain row or a certain column of laser emitters by sharing a GaN switching device, which reduces cost and volume of an emitting end, and makes the size of the GaN switching device no longer the limit of vertical angular resolution of the lidar. The GaN switching device can be arranged at both sides of the plurality of laser emitters, or use a wiring method of PCB back wiring, which causes emitting power and various parameters of the plurality of laser emitters to tend to be consistent, thereby improving performance of the lidar. In addition, by interlacing the plurality of laser emitters, the angular resolution in the vertical direction is also increased. 
     An exemplary embodiment of the present disclosure provides a power supply unit including an LC resonant circuit. Due to the characteristics of the LC resonant circuit, a charge-discharge speed of the power supply unit for a mounted capacitor is greatly improved. Compared with a solution of a feedback circuit used in the prior art, the speed is increased by a thousand times, which can adjust light intensity of a plurality of laser emitters of the lidar relatively faster, to match with an external obstacle situation or a scenario of use, thereby improving accuracy of point cloud detection. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       The accompanying drawings are used to provide a further understanding of the present disclosure, and form a part of the specification, are used to explain the present disclosure in combination with the embodiments of the present disclosure, and do not form a limitation to the present disclosure. In the accompanying drawings: 
         FIG.  1 A  schematically shows an emitting apparatus for a lidar under a single-bus power supply system; 
         FIG.  1 B  schematically shows a circuit structure in which one GaN switching device drives one laser emitter; 
         FIG.  2 A  schematically shows an arrangement of components on a PCB under a single-bus power supply system; 
         FIG.  2 B  schematically shows an arrangement of components on a PCB under a single-bus power supply system; 
         FIG.  3    schematically shows an emitting apparatus according to an exemplary embodiment of the present disclosure; 
         FIG.  4 A  schematically shows an emitting apparatus according to an exemplary embodiment of the present disclosure; 
         FIG.  4 B  schematically shows a specific implementation structure of a three-bus emitting apparatus according to an embodiment of the present disclosure; 
         FIG.  4 C  shows a waveform of an output voltage according to the exemplary embodiment shown in  FIG.  4 B ; 
         FIG.  4 D  schematically shows a specific implementation structure of a two-bus emitting apparatus according to an embodiment of the present disclosure; 
         FIG.  4 E  shows a waveform of an output voltage according to the exemplary embodiment shown in  FIG.  4 D ; 
         FIG.  5    schematically shows an arrangement of components on a PCB under a two-bus power supply system according to an exemplary embodiment of the present disclosure; 
         FIG.  6    schematically shows a wiring method of components on a PCB under a two-bus power supply system according to an exemplary embodiment of the present disclosure; 
         FIG.  7    schematically shows an arrangement of components on a PCB under a four-bus power supply system according to an exemplary embodiment of the present disclosure; 
         FIG.  8    schematically shows a power supply unit for a laser emitter according to an exemplary embodiment of the present disclosure; 
         FIG.  9 A  schematically shows a specific implementation structure of a power supply unit; 
         FIG.  9 B  schematically shows a simulation curve of operating of the power supply unit in  FIG.  9 A ; 
         FIG.  9 C  schematically shows a specific implementation structure of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  10 A  schematically shows a first charge process of a high-voltage generation unit according to an exemplary embodiment of the present disclosure; 
         FIG.  10 B  shows change curves of a first inductor and an output voltage of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  11 A  schematically shows a second charge process of a high-voltage generation unit according to an exemplary embodiment of the present disclosure; 
         FIG.  11 B  shows change curves of a first inductor and an output voltage of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  12 A  schematically shows a first discharge process of a high-voltage generation unit according to an exemplary embodiment of the present disclosure; 
         FIG.  12 B  shows change curves of a first inductor and an output voltage of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  13 A  schematically shows a second discharge process of a high-voltage generation unit according to an exemplary embodiment of the present disclosure; 
         FIG.  13 B  shows change curves of a first inductor and an output voltage of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  14 A  schematically shows a reset process of a high-voltage generation unit according to an exemplary embodiment of the present disclosure; 
         FIG.  14 B  shows change curves of a first inductor and an output voltage of a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  15    shows a method for controlling a laser emitter to emit light by using a power supply unit according to an exemplary embodiment of the present disclosure; 
         FIG.  16    schematically shows a lidar according to an exemplary embodiment of the present disclosure; 
         FIG.  17    schematically shows an application scenario of a lidar according to an exemplary embodiment of the present disclosure; 
         FIG.  18    shows a four-bus driving apparatus for a lidar; 
         FIG.  19    shows a charge-discharge curve of a capacitor of a multi-bus driving apparatus in an operating process; 
         FIG.  20    shows a switching loss, a charge loss, and a total loss of a multi-bus driving apparatus in an operating process; 
         FIG.  21    shows a multi-bus driving apparatus for a lidar according to an embodiment of the present disclosure; 
         FIG.  22    shows a four-bus driving apparatus for a lidar according to an embodiment of the present disclosure; 
         FIG.  23    shows an energy transfer unit of a multi-bus driving apparatus according to an embodiment of the present disclosure; 
         FIG.  24    shows an energy transfer unit of a multi-bus driving apparatus according to an embodiment of the present disclosure; 
         FIG.  25    shows an energy transfer unit of a multi-bus driving apparatus according to an embodiment of the present disclosure; 
         FIG.  26    shows an energy transfer unit of a multi-bus driving apparatus according to an embodiment of the present disclosure; and 
         FIG.  27    shows an eight-bus driving apparatus and an energy transfer unit thereof according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Only some exemplary embodiments are briefly described below. As a person skilled in the art may understand, the described embodiments may be modified in various different ways without departing from the spirit or the scope of the present disclosure. Therefore, the accompanying drawings and the description are to be considered as illustrative in nature but not restrictive. 
     In the description of the present disclosure, it should be understood that directions or location relationships indicated by terms “center”, “longitudinal”, “landscape”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, and “counterclockwise” are directions or location relationships shown based on the accompanying drawings, are merely used for the convenience of describing the present disclosure and simplifying the description, but are not used to indicate or imply that an apparatus or an element needs to have a particular direction or be constructed and operated in a particular direction, and therefore, cannot be understood as a limitation to the present disclosure. In addition, terms “first” and “second” are only used to describe the objective and cannot be understood as indicating or implying relative importance or implying a quantity of the indicated technical features. Therefore, a feature restricted by “first” or “second” may explicitly indicate or implicitly include one or more such features. In the descriptions of the present disclosure, unless otherwise explicitly specified, “a plurality of” means two or more than two. 
     In the descriptions of the present disclosure, it should be noted that, unless otherwise explicitly specified or defined, the terms such as “install”, “connect”, and “connection” should be understood in a broad sense. For example, the connection may be a fixed connection, a detachable connection, or an integral connection; or, the connection may be a mechanical connection, an electrical connection, or mutual communication; or, the connection may be a direct connection, an indirect connection through an intermediate, or internal communication between two elements or an interaction relationship between two elements. A person of ordinary skill in the art may understand the specific meanings of the foregoing terms in the present disclosure according to specific situations. 
     In the present disclosure, unless otherwise explicitly specified or defined, that a first feature is “on” or “under” a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but in contact by using other features there between. In addition, that the first feature is “on”, “above”, or “over” the second feature includes that the first feature is right above and on the inclined top of the second feature or merely indicates that a level of the first feature is higher than that of the second feature. That the first feature is “below”, “under”, or “beneath” the second feature includes that the first feature is right below and at the inclined bottom of the second feature or merely indicates that a level of the first feature is lower than that of the second feature. 
     Many different implementations or examples are provided in the following disclosure to implement different structures of the present disclosure. To simplify the disclosure of the present disclosure, components and arrangements in particular examples are described below. Certainly, they are merely examples and are not intended to limit the present disclosure. In addition, in the present disclosure, reference numerals and/or reference letters may be repeated in different examples. The repetition is for the purposes of simplification and clearness, and does not indicate a relationship between various implementations and/or arrangements discussed. Moreover, the present disclosure provides examples of various particular processes and materials, but a person of ordinary skill in the art may be aware of application of another process and/or use of another material. 
     The embodiments of the present disclosure are described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are merely used to illustrate and explain the present disclosure but are not intended to limit the present disclosure. 
     First Aspect 
     It is proper to speculate that due to upgrade of a lidar product, the lidar tends to be designed on chip in terms of various aspects such as the difficulty of assembly, cost, and miniaturization. A laser emitter used by a future lidar may be packaged as a chip, and a driving circuit used to drive the laser emitter may also be packaged as a chip. Due to the limitation of the current process, most laser emitters share a cathode. Therefore, the cathodes of a plurality of laser emitters packaged in the chip of the laser emitter are made together, and then connected to ground (GND), so other devices cannot be arranged between the cathode of each laser emitter and the GND. If the driving circuit is arranged between the cathode of the laser emitter and the GND, because the cathodes of the plurality of laser emitters are connected, the plurality of laser emitters need to share a switching device for inputting a driving signal. If the plurality of laser emitters need to be activated to each other separately (for example, a laser emitter 1 may be individually activated, to make the laser emitter 1 emit light, while a laser emitter 2 does not emit light; or, the laser emitter 2 may be individually activated, to make the laser emitter 2 emit light, while the laser emitter 1 does not emit light; it is not necessary to activate the laser emitter 1 and the laser emitter 2 at the same time), one solution is that the switching device can be arranged on the anode of the laser emitter to drive, but this solution requires a high-side switch. To achieve this regulation, the solution is relatively complex. Based on the purpose of implementing that the plurality of laser emitters can be independently activated, and the motivation of saving GaN, this application proposes a technical solution that the plurality of laser emitters are provided with power supplies respectively and no longer share a power supply. The solution of this application is described and introduced in detail below in combination with  FIG.  3    to  FIG.  17   . 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  3   , the present disclosure provides an emitting apparatus  10  for a lidar, including a plurality of power supply units  11 , such as a power supply unit  11 - 1 , a power supply unit  11 - 2  to a power supply unit  11 -N, a laser emitter unit  12 , and at least one switching device  13  shown in the figure. 
     The plurality of power supply units  11  are configured to convert a preparatory voltage into a high voltage to output (HV 1 , HV 2 , . . . , and HVN shown in the figure, the following uses a high voltage HVx to refer to any one of the high voltage HV 1 , and HV 2  to HVN, and the high voltage HVx is a voltage higher than the preparatory voltage), and at least two power supply units  11  output the high voltage at different times. For example, the power supply unit  11 - 1  may output the high voltage HV 1  at a time t1, and the power supply unit  11 - 2  may output the high voltage HV 2  at a time t2, where t1≠t2. 
     The laser emitter unit  12  includes a plurality of laser emitters  121 , such as a laser emitter  121 - 1 , and a laser emitter  121 - 2  to a laser emitter  121 -N shown in the figure. The laser emitter unit  12  may be a one-dimensional laser emitter or a two-dimensional laser emitter array. Correspondingly, a laser emitter  121 - x  (including the laser emitter  121 - 1 , the laser emitter  121 - 2 , . . . , and the laser emitter  121 -N) shown in  FIG.  3    may be one laser emitter, one column of laser emitters, or one row of laser emitters. In a connection relationship, the anode of each laser emitter  121 - x  is connected to an output end of the power supply unit  11 . At least two laser emitters  121 - x  may be connected to different power supply units  11 . For example, the anode of the laser emitter  121 - 1  is connected to the output end of the power supply unit  11 - 1 , and the anode of the laser emitter  121 - 2  is connected to the output end of the power supply unit  11 - 2 . There is at least one switching device  13 . The cathodes of a subnet of laser emitters that do not share a high voltage (such as the laser emitter  121 - 2 , . . . , and the laser emitter  121 -N shown in the figure) are connected to the same switching device  13 . The switching device  13  is configured to control a connection state of a discharging loop formed by the corresponding output high voltage HVx, the laser emitter connected to the switching device  13 , and the ground (GND). For example, when the power supply unit  11 - 1  outputs the high voltage HV 1  at the time t1, if the switching device  13  is also closed at the time t1, the discharging loop formed by the high voltage HV 1 , the laser emitter  121 - 1  connected to the switching device  13 , and the ground can be activated. 
     By using the solution provided in the present disclosure, even if the plurality of laser emitters share the same switching device  13 , by at least two power supply units  11  (including the power supply unit  11 - 1 , the power supply unit  11 - 2 , . . . , and the power supply unit  11 -N) outputting the high voltage at different times, a subnet of laser emitters  121 - x  in the laser emitter unit  12  (the laser emitter unit  12  includes the laser emitter  121 - 1 , the laser emitter  121 - 2 , . . . , and the laser emitter  121 -N) can still be individually activated one by one. It is easy for a person skilled in the art to understand that the laser emitter  121  in the laser emitter unit  12  shown in  FIG.  3    is one laser emitter. In another embodiment, the laser emitter  121  may also be one column of a plurality of laser emitters or one row of a plurality of laser emitters, which can overcome the defect of insufficient light intensity of one laser emitter and further improve a long-range measurement capability of the lidar. In addition, different power supply units  11  output different high voltages (such as HV 1 =20 V, HV 2 =40 V) to control a subnet of laser emitters  121  in the laser emitter unit  12  to detect with different emission intensity, which also falls within the protection scope of the present disclosure. 
     To facilitate understanding, in the present disclosure, the components constituting the power supply unit and the lines connecting the corresponding components are collectively referred to as a voltage bus. A plurality of voltage buses (BUS) connect functional components of the power supply unit  11  together to form a HVBUS. Specifically, one Vbase and one boost circuit together form one power supply unit  11 , the output of this power supply unit  11 , for the lidar, is to supply the high voltage HV 1 , thereby forming one voltage bus HVBUS. One Vbase and another boost circuit together form another power supply unit  11 , the output of this power supply unit  11 , for the lidar, is to supply the high voltage HV 2 , thereby forming another voltage bus HVBUS.  FIG.  4 A  shows an embodiment of a two-bus power supply system according to the present disclosure. Two buses share one preparatory voltage source  112 . Specifically, the emitting apparatus  10  includes a plurality of voltage buses  14  corresponding to the plurality of power supply units  11 . An input end of the voltage bus  14  receives a preparatory voltage (i.e. VBASE shown in the figure), and an output end outputs a voltage higher than the preparatory voltage (i.e. HV 1  and HV 2  shown in the figure). Each laser emitter  121 - x  is connected to the output end of the corresponding power supply unit  11  through one of the voltage buses  14 . 
     It is easy for a person skilled in the art to understand that although  FIG.  4 A  shows a case of two buses, the emitting apparatus  10  includes the plurality of voltage buses  14  which respectively output voltages HV 1 , and HV 2  to HVN higher than the preparatory voltage (VBASE), that is, HVx&gt;VBASE. The plurality of voltage buses  14  may not share the preparatory voltage source  112 , which also falls within the protection scope of the present disclosure. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  4 A , the power supply unit  11  of the emitting apparatus  10  includes a capacitor unit  111  connected to the voltage bus  14 , and the capacitor unit  111  is configured to be charged through the voltage bus  14 , and be discharged to one or more laser emitters  121 - x  connected to the voltage bus  14  and activated by the switching device  13  when the switching device  13  is closed, to drive the one or more laser emitters  121 - x  to emit light. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  4 A , the power supply unit  11  further includes a preparatory voltage source  112  and a high-voltage generation unit  113 . The preparatory voltage source  112  is configured to output a primary voltage (VBASE). The high-voltage generation unit  113  is connected to the preparatory voltage source  112 , the preparatory voltage source  112  is suitable for outputting the preparatory voltage (VBASE) to the high-voltage generation unit  113 , and the high-voltage generation unit  113  is configured to generate a voltage Hvx higher than the preparatory voltage (VBASE). 
     To facilitate a person skilled in the art to better understand and implement the present disclosure,  FIG.  9 C  shows a circuit of a voltage bus,  FIG.  4 B  shows a laser emitter circuit of three voltage buses, and  FIG.  4 D  shows a laser emitter circuit of two voltage buses. As shown in  FIG.  4 B , an inductor Lx (including an inductor L 1 , an inductor L 2 , and an inductor L 3 ), a gatex signal (including a gate 1 , a gate 2 , and a gate 3 ), a switch Mx (including a switch M 1 , a switch M 2 , and a switch M 3 ), and a diode Dx (including D 1 , D 2 , and D 3 ) form an energy storage circuit. A high-side transistor Px (including a high-side transistor P 1 , a high-side transistor P 2 , and a high-side transistor P 3 ) and a high-side transistor driver (including a driver  1 , a driver  2 , and a driver  3 ) form an activated circuit. LD 1 -Ldx (including LD 1 , LD 2 , and LD 3 ) and a trigger signal form a laser emitter circuit. In addition, the diodes D 11 , D 21 , and D 31  are configured to protect respective parallel switches. For example, the diode D 11  protects M 1 . The energy storage circuit  1  includes the inductor L 1 , the gate 1 , the switch M 1 , and the diode D 1 . The activated circuit  1  includes the high-side transistor P 1  and the driver  1 . The specific composition of another energy storage circuit x and the activate circuit x may be analogized. Details are not described herein again. 
     The general operating process of the laser emitter to emit light is as follows: the energy storage circuit is configured to receive the input preparatory voltage VBase and store electrical energy, then the activated circuit is closed, and an energy storage inductor can charge a boost capacitor C and establish a high voltage on the boost capacitor C. Generally, the input voltage is not excessively high, such as 5 V or 12 V, which cannot be directly used to drive the laser emitter, and the voltage needs to be boosted. The high voltage established on the boost capacitor C can be significantly higher than the input voltage VBase, such as, 60 V, which can be used to drive the laser emitter LD. After the high voltage is established, the boost capacitor C can drive the laser emitter LDx to emit a laser beam. Three HV buses share one preparatory voltage source VBase, and three laser emitters LD share one driving device S 3 . These three HV buses HV 1 , HV 2 , and HV 3  are not output at the same time point. At a certain time, only one of the HV 1 , HV 2 , and HV 3  is output, so as to activate the discharging loop of the output capacitor C, HV, S 3 , and the ground (it can be understood that whether a certain energized loop is a charging loop or a discharging loop is a relative concept, which is a charging loop for the laser emitter, and a discharging loop for the capacitor C), and drive the laser emitter LD connected to the HV to emit light. The laser emitter LD may be various types of laser emitters, such as a vertical cavity surface emitting laser VCSEL, or an edge emitting laser EEL. The protection scope of the present disclosure is not limited by the type of the laser emitter. 
     Referring to  FIG.  4 B , specifically, how the energy storage circuit, the activated circuit, and the laser emitter circuit operate with each other is described by using examples of the energy storage circuit  1 , the activated circuit  1 , and LD 1 . The energy storage circuit  1  includes the inductor L 1 , and the diode D 1  and the switch M 1  that are connected to the inductor L 1 . One end of the inductor L 1  is connected to the input voltage VIN (generally small, such as 5 V), and the other end is connected to the diode D 1  and the switch M 1 . 
     If the HV 1  is selected to be output at a certain time, in an energy storage stage, the switch M 1  is controlled to be closed through the gate 1 . The closed switch M 1  can be equivalent to a short circuit in the circuit. Therefore, the current generated by the input voltage VIN flows through the inductor L 1  and is connected to ground through the switch M 1 . With the increase of the current of the inductor, the electrical energy is stored in the inductor L 1 . 
     After the energy storage stage is completed, the switch M 1  is disconnected. P 1  is activated through the high-side driver in the activated circuit  1 . At this time, due to the current holding characteristics of the inductor L 1 , the current flowing through the inductor L 1  does not immediately become zero, but slowly becomes zero from the current value when charging is completed. In this process, the switch M 1  is disconnected and P 1  is closed, therefore, the inductor L charges the boost capacitor C 1 , and the voltages at both ends of the boost capacitor C 1  increase. 
     After the high voltage (such as 60 V) is established on the boost capacitor C 1 , if the driving switch S 3  in the laser emitter circuit is selected to be closed (may be closed or disconnected through a trigger 3  signal), due to the unidirectional conductivity of the diode D 1 , the capacitor C 1  cannot discharge through the diode D 1 , and can only discharge through a loop of the laser emitter LD 1  and the switch S 3 . Therefore, the current flows through the laser emitter LD 1 , and the capacitor C 1  drives the laser emitter LD 1  to emit light. 
     If the laser emitter LD 2  is driven to emit light at the next moment, the energy storage circuit  2 , the activated circuit  2 , and the LD 2  can repeat the operating process of the energy storage circuit  1 , the activated circuit  1 , and the LD 1 . If the laser emitter LD 3  is driven to emit light at the next moment, the energy storage circuit  3 , the activated circuit  3 , and the LD 3  can repeat the operating process of the energy storage circuit  1 , the activated circuit  1 , and the LD 1 . Details are not described herein again. 
       FIG.  4 C  provides a simulation diagram of the operating of the laser emitter circuit shown in  FIG.  4 B . The horizontal axis is time t and the vertical axis is voltage V. A curve  401  represents the change of the HV 1 , a curve  402  represents the change of the HV 2 , and a curve  403  represents the change of the HV 3 . It can be seen from the figure that the HV 1  is output within a period from 0.5 μs to 3.5 μs, the HV 2  is output within a period from 5.5 μs to 8.5 μs, and the HV 3  is output within a period from 10.5 μs to 13.5 μs. The output time of the HV 1 , HV 2 , and HV 3  does not coincide, and one or more laser emitters connected to the voltage buses outputting the HV 1 , HV 2  and HV 3  can be respectively activated to emit light. 
     In order to facilitate a person skilled in the art to understand the present disclosure,  FIG.  4 D  shows a solution of a two-bus laser emitter circuit. Next, another embodiment of this application is introduced with reference to  FIG.  4 D  and  FIG.  9 C . As shown in the figure, the high-voltage generation unit  113  includes a first inductor  1131 , a first switch  1132 , and a second switch  1133 . The first inductor  1131  has a first end connected to the preparatory voltage source  112 , and is configured to receive electrical energy from the preparatory voltage source  112 . The first switch  1132  has a first end connected to a second end of the first inductor  1131  and a second end connected to ground, the first switch configured to, upon being closed cause the preparatory voltage source  112  and the first inductor  1131  to form a charging loop, and cause the first inductor  1131  to be charged. The second switch  1133  has a first end connected to the second end of the first inductor  1131  and a second end connected to the capacitor unit  111 , the second switch configured to, upon being closed cause the preparatory voltage source  112  and the first inductor  1131  to form a discharging loop, and cause the capacitor unit  111  to be charged. In addition, the diodes D 1  are configured to protect respective parallel switches. For example, the diode D 1  protects the first switch  1132 . The diode D 2  is configured to accelerate the conduction and power supply. For example, the diode D 2  accelerates the supply of the HV 2 . Compared with the solution in  FIG.  4 B , the capacitance value of the capacitor C that can be selected to charge the laser emitter in this embodiment is relatively larger. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  4 D , the high voltages output by the two voltage buses are the HV 1  and the HV 2  respectively, and a certain quantity of laser emitters  121  are mounted on each bus (specifically, as shown in  FIG.  4 D,  121 - 1 ,  121 - 3  and  121 - 5    are mounted on the voltage bus with the output voltage of the HV 1 , and  121 - 2 ,  121 - 4  and  121 - 6  are mounted on the voltage bus with the output voltage of the HV 2 ). Two adjacent laser emitters share a GaN switch as a driver (specifically, as shown in  FIG.  4 D , the laser emitters  121 - 1  and  121 - 2  share the GaN switch  13 - 1 , the laser emitters  121 - 3  and  121 - 4  share the GaN switch  13 - 2 , and the laser emitters  121 - 5  and  121 - 6  share the GaN switch  13 - 3 ). The driving signal DRV 1  shown in the figure is used to drive the GaN switch  13 - 1 , and determine on/off and an on/off duration of the GaN switch  13 - 1 . Similarly, the driving signal DRV 2  shown in the figure is used to drive the GaN switch  13 - 2 , and determine on/off and an on/off duration of the GaN switch  13 - 2 . DRV 3  is used to drive the GaN switch  13 - 3 , and determine on/off and an on/off duration of the GaN switch  13 - 3 . 
     As shown in  FIG.  4 D  and  FIG.  9 C , the high-voltage generation unit  113  of the power supply unit  11  has three control signals, that is, a low-side driving signal DRVL_HV 1  (for driving the first switch  1132 ), a high-side driving signal DRVH_HV 1  (for driving the second switch  1133 ), and a reset driving signal DRVRST_HV 1  (for driving the reset switch  1134 ) shown in the figure. Input ends of the control signals of the low-side driving signal DRVL_HV 1 , the high-side driving signal DRVH_HV 1 , and the reset driving signal DRVRST_HV 1  together form a voltage control end of the power supply unit  11 . According to an exemplary embodiment of the present disclosure, the voltage control end can receive an external voltage control signal to control the power supply unit  11  to output the voltage. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  4 A , each switching device  13  includes a control end (the input ends of the driving signals DRV 1 , DRV 2 , and DRV 3  shown in the figure), a first end, and a second end. The control end is configured to receive the driving signal to control on/off between the first end and the second end. The first end is connected to the cathodes of one or more laser emitters  121  activated by the switching device. The second end is connected to ground. The voltage control signal and the driving signal cooperate with each other to control the laser emitter  121  to emit light. Preferably, the switching device  13  includes one or more of a GaN switch and a CMOS switch. 
       FIG.  4 E  provides a simulation diagram of the operating of the laser emitter circuit shown in  FIG.  4 D . The horizontal axis is time t and the vertical axis is voltage V. A relatively thin curve  404  represents the change of the HV 1 , and a relatively thick curve  405  represents the change of the HV 2 . It can be seen from the figure that the HV 1  is output within a period from 0.5 μs to 3.5 μs, and the HV 2  is output within a period from 5.5 μs to 8.5 μs. The output time of the HV 1  and HV 2  does not coincide, and one or more laser emitters connected to the voltage buses outputting the HV 1 , and HV 2  can be respectively activated to emit light. 
     According to an exemplary embodiment of the present disclosure, the present disclosure further provides a method for controlling the emitting apparatus  10  as described above (as shown in  FIG.  4 A ) to emit light, which may include the following steps: 
     Step S 201 : Control a power supply unit  11  to output a high voltage. 
     Step S 202 : Control a current loop of a subnet of laser emitters  121  to be connected through a switching device  13 , so that the laser emitters  121  connected to the power supply unit  11  emit light under the action of the high voltage. 
     According to an exemplary embodiment of the present disclosure, the emitting apparatus  10  further includes a plurality of voltage buses  14  corresponding to a plurality of power supply units  11 , where each voltage bus  14  is connected to components on the corresponding power supply units  11 , an input end of the voltage bus  14  receives a preparatory voltage, an output end outputs a voltage higher than the preparatory voltage, each laser emitter  121  is connected to the output end of the corresponding power supply unit  11  through one of the voltage buses  14 , and the power supply unit  11  includes a capacitor unit  111 , connected to the voltage bus  14 . The control method further includes: 
     charging the capacitor unit  111  through the voltage bus  14 , and discharging the corresponding laser emitter  121  connected to the same voltage bus  14  through the capacitor unit  111 , to drive the corresponding laser emitter  121  to emit light. 
     According to an exemplary embodiment of the present disclosure, the power supply unit  11  further includes a preparatory voltage source  112  and a high-voltage generation unit  113 . 
     The control method further includes: 
     outputting the preparatory voltage through the preparatory voltage source  112 ; and 
     generating a voltage higher than the preparatory voltage by the high-voltage generation unit  113 ; and outputting the voltage via the voltage bus  14 . 
     According to an exemplary embodiment of the present disclosure, the high-voltage generation unit  113  includes: a first inductor  1131 , a first end of which is connected to the preparatory voltage source  112 , a first switch  1132  having a first end connected to a second end of the first inductor  1131  and a second end connected to ground, and a second switch  1133  having a first end connected to the second end of the first inductor  1131  and a second end connected to the capacitor unit  111 . The control method further includes: 
     outputting electrical energy from the preparatory voltage source  112  through the first inductor  1131 ; 
     causing the preparatory voltage source  112  and the first inductor  1131  to form a charging loop by connecting the first switch  1132 , thus charging the first inductor  1131 ; and 
     causing the preparatory voltage source  112  and the first inductor  1131  to form a discharging loop by connecting the second switch  1133 , thus charging the capacitor unit  111 . 
     According to an exemplary embodiment of the present disclosure, the power supply unit  11  further includes a voltage control end. The control method further includes: 
     receiving a voltage control signal through the voltage control end, to control the power supply unit  11  to output the voltage. 
     According to an exemplary embodiment of the present disclosure, each switching device  13  includes a control end, a first end, and a second end, where the control end is configured to receive a driving signal to control a connection state between the first end and the second end, the first end is connected to a cathode of a laser emitter activated by the switching device  13 , and the second end is connected to ground. The control method further includes: 
     cooperating the voltage control signal and the driving signal with each other to control one or more laser emitters corresponding to the switching device  13  to emit light. 
     The present disclosure provides a method of arranging the emitting apparatus  10  as described above on a PCB: As shown in  FIG.  5   , a plurality of laser emitters  121  are arranged in a single column, and the GaN switching device corresponding to adjacent laser emitters may be arranged on both sides. As shown in the figure, the laser emitters  121 - 1  and  121 - 2  correspond to the GaN switch  13 - 1 , and the laser emitters  121 - 3  and  121 - 4  correspond to the GaN switch  13 - 2 . The laser emitters  121 - 0  and  121 - 1  are supplied with the high voltage HV 3  through the capacitor  111 - 3 . The laser emitters  121 - 2  and  121 - 3  are supplied with the high voltage HV 1  through the capacitor  111 - 1 . The laser emitter  121 - 4  is supplied with the high voltage HV 2  through the capacitor  111 - 2 . The high voltages HV 1 , HV 2 , and HV 3  may not be supplied simultaneously, that is, at different times, so that any one of the plurality of laser emitters  121  can be individually activated and controlled. A ratio of a quantity of the laser emitters to a quantity of the GaN switching devices is 2:1, which is equivalent to that two laser emitters share one GaN switching device. These two laser emitters are driven by the GaN device to emit light. It is easy to implement in the foregoing plurality of exemplary embodiments by using the emitting apparatus of the present disclosure. The switching devices are arranged on both sides of the laser emitters in the single column, so that distances between the plurality of laser emitters and the switching devices activating the laser emitters are approximately equal, and there is no inconsistency in a test parameter, resulting in a better consistency of detection channels. Compared with the arrangement of one GaN switching device drives one laser emitter (as shown in  FIG.  2 A  and  FIG.  2 B ), the length of the discharging loop is basically the same, and emitting powers of the laser emitters are also substantially the same. 
     As shown in  FIG.  6   , the present disclosure further provides another method for arranging the emitting apparatus  10  as described above on a PCB: A plurality of laser emitters  121  are arranged in a single column. A GaN switching device and a capacitor C are arranged on the same side of the laser emitters in the column. A wiring is divided into three layers. The first layer of wiring is connected to ground and connects the GaN switching and the capacitor. The second layer of wiring connects the GaN switching device and the laser emitter. The third layer of wiring connects all capacitors. A capacitor unit mounted on the voltage bus of the output voltage HV 1  is connected to the corresponding laser emitter on the first layer of wiring. A capacitor unit mounted on the voltage bus of the output voltage HV 2  is connected to the corresponding laser emitter on the second layer of wiring. Since the quantity of the GaN devices is less than the quantity of the laser emitters, such wiring method can also make the distances between the laser emitters and the GaN switching device driving the laser emitters equal, so that the discharging loops of the laser emitters are roughly equal, and there is no difference in the emitting power. 
     According to an exemplary embodiment of the present disclosure,  FIG.  7    shows an arrangement method of an emitting apparatus  10  of a four-bus power supply system on a PCB: The two columns of laser emitters are staggered. The laser emitters  121 - 1 ,  121 - 2 ,  121 - 3 , and  121 - 4  shown in the figure are respectively connected to four different power supply units (as shown in the figure, the output voltages of the four power supply units are HV 1 , HV 2 , HV 3 , and HV 4  respectively). The four laser emitters  121 - 1 ,  121 - 2 ,  121 - 3 , and  121 - 4  share a GaN switch  13 - 1 , which reduces the quantity of the GaN switching devices. The GaN switch  13 - 1  connects the laser emitters  121 - 1  and  121 - 3  by wiring on the PCB, and connects the laser emitters  121 - 2  and  121 - 4  by wiring on the back side of the PCB, so that the distances between the four laser emitters  121 - 1 ,  121 - 2 ,  121 - 3  and  121 - 4  and the GaN switch  13 - 1  driving the laser emitters are approximately equal, the discharging loops of the laser emitters are equal, and the emitting power of the plurality of laser emitters is consistent. The staggered arrangement of the laser emitters in the two columns can double the density of placement of the laser emitters, thereby doubling the vertical angular resolution of the lidar. 
     In this exemplary embodiment, all GaN switching devices are arranged on one side, and each GaN switching device corresponds to a plurality of laser emitters, which can ensure the consistency of the wiring between the plurality of laser emitters and the GaN switching device corresponding to the laser emitters. In addition, since two GaN switching devices, such as the GaN switch  13 - 1  and the GaN switch  13 - 2  shown in the figure, are farther apart, and there is more room in the arrangement space. The four laser emitters  121 - 1 ,  121 - 2 ,  121 - 3 , and  121 - 4  shown in  FIG.  7    correspond to different capacitors  111 - 2  and  111 - 5  respectively. Each laser emitter, the capacitor corresponding thereto and the GaN switching device together form an energized loop. Therefore, the four laser emitters can emit light respectively according to a certain time sequence. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  16   , the present disclosure further provides a lidar  20 , including the emitting apparatus  10  as described above, a receiving apparatus  21 , and a control apparatus  22 . The emitting apparatus  10  is suitable for driving laser emitters to emit a detection laser beam according to a certain time sequence under the control of the control apparatus  22 . The receiving apparatus  21  is suitable for receiving an echo reflected by an external obstacle relative to the lidar. The control apparatus  22  is suitable for generating a voltage control signal (DRVH_HV 1 , DRVL_HV 1 , or DRVRST_HV 1  shown in  FIG.  4 D ) according to a detection demand of the lidar, controlling a power supply unit to output a voltage, and generating a driving signal (DRV 1 , DRV 2 , or DRV 3  shown in  FIG.  4 A ) to activate a subnet of the laser emitters to emit light; and is suitable for processing the echo received by the receiving apparatus  21 , and calculating a distance between the external obstacle and the lidar and/or reflectivity according to an echo signal. 
     According to an exemplary embodiment of the present disclosure,  FIG.  17    shows an application scenario of the present disclosure. An unmanned vehicle is equipped with the lidar  20 . The emitting apparatus  10  in the lidar  20  outputs voltages at different times through different power supply units under the control of the control apparatus  22 , and respectively activates a subnet of the laser emitters to emit the detection beam. The receiving apparatus  21  receives the echo of the detection beam reflected by the external obstacle, and calculates the distance between the external obstacle and the lidar (unmanned vehicle) and/or reflectivity according to the echo signal through the processing by the control apparatus  22 . The control apparatus  22  controls the plurality of power supply units of the emitting apparatus  10  to output the voltage by generating the voltage control signal, and activates a subnet of the laser emitters to emit light by generating the driving signal. 
     An exemplary embodiment of the present disclosure provides an emitting apparatus for a lidar and a control method thereof. A plurality of power supply units are used to activate laser emitters connected to the power supply units to emit light, a plurality of laser emitters that do not share a voltage can share a GaN switching device to activate a certain laser emitter or a certain row or a certain column of laser emitters individually, one by one, which reduces cost and volume of an emitting end, and makes the size of the GaN switching device no longer the limit of vertical angular resolution of the lidar. The GaN switching device may be arranged at both sides of the plurality of laser emitters, or use a wiring method of wiring on back of PCB, so that emitting power of the plurality of laser emitters is consistent, the plurality of laser emitters are staggered, and the angular resolution in the vertical direction is increased. 
     Second Aspect 
     In order to achieve rapid adjustment of the voltage of the power supply HV, rapid boost from the preparatory voltage, and rapid adjustment of the output voltage, thereby achieving rapid adjustment of the light intensity of the laser emitter, as shown in  FIG.  9 C , the present disclosure further provides a power supply unit  11  of a laser emitter, including: a capacitor unit  111 , a preparatory voltage source  112 , and a high-voltage generation unit  113 . The preparatory voltage source  112  is configured to output a preparatory voltage. The high-voltage generation unit  113  is coupled to the preparatory voltage source  112 , and configured to receive the preparatory voltage, generate an output voltage higher than the preparatory voltage, and output the output voltage via an output end. The capacitor unit  111  is coupled to the output end of the high-voltage generation unit  113 . The capacitor unit  111  and the high-voltage generation unit  113  are configured to cooperatively adjust the output voltage through charge and discharge processes. 
       FIG.  9 C  shows a specific implementation structure of a power supply unit  11  according to an exemplary embodiment of the present disclosure. The preparatory voltage source  112  outputs the preparatory voltage (VBASE 1  shown in the figure). The high-voltage generation unit  113  is coupled to the preparatory voltage source  112  to convert the preparatory voltage VBASE 1  into a high voltage to output (HV 1  shown in the figure). The capacitor unit  111  is coupled to the output end of the high-voltage generation unit  113 , and cooperatively adjusts the output voltage HV 1  together with the high-voltage generation unit  113  through charge and discharge processes. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  9 C , the high-voltage generation unit  113  includes: a first inductor  1131 , a first switch  1132 , and a second switch  1133 . The first inductor  1131  has a first end connected to the preparatory voltage source  112 , and is configured to receive electrical energy from the preparatory voltage source  112 . The first switch  1132  has a first end connected to a second end of the first inductor  1131  and a second end connected to ground, the first switch configured to, upon being closed cause the preparatory voltage source  112  and the first inductor  1131  to form a charging loop, and cause the first inductor  1131  to be charged. The second switch  1133  has a first end connected to the second end of the first inductor  1131 , and a second end connected to the capacitor unit  111  as the output end of the high-voltage generation unit  113 . 
     As shown in  FIG.  10 A , in a direction of a current flow of a charge stage, the first switch  1132  is closed, the second switch  1133  is disconnected, and the preparatory voltage source  112  and the first inductor  1131  form a charging loop. As shown in  FIG.  10 B , the horizontal axis is time. The upper curve is the curve of the current of the first inductor  1131  varied with time, and the lower curve is the curve of the output voltage HV 1  of the power supply unit  11  varied with time. The first switch  1132  is closed. At this time, the current of the first inductor  1131  rises linearly according to a slope of VBASE/L, where L is inductance of the first inductor  1131 . The output voltage HV 1  of the power supply unit  11  maintains an initial value (equal to VBASE). 
     As shown in  FIG.  11 A , in a direction of a current flow of a charge stage  2 , the first switch  1132  is disconnected, and since the current on the first inductor  1131  cannot suddenly change, reverse electromotive force Vls is generated on an inductor Ls to maintain the passing current unchanged. At this time, the second switch  1133  is closed. After the preparatory voltage source  112  and the first inductor  1131  are connected in series, the capacitor unit  111  is charged with a voltage greater than VBASE, so that the voltage of the capacitor unit  111  rises to VBASE+VLs. As shown in  FIG.  11 B , the horizontal axis is time. The upper curve is the curve of the current of the first inductor  1131  varied with time, and the lower curve is the curve of the output voltage HV 1  of the power supply unit  11  varied with time. The first switch  1132  is disconnected and the second switch  1133  is closed. At this time, the first inductor  1131  and the capacitor unit  111  form resonance. The voltage of the capacitor unit  111  resonantly rises from the initial voltage VBASE. When the current of the first inductor  1131  decreases to zero, the second switch  1133  is disconnected, and at this time, the capacitance of the capacitor unit rises to a target voltage. 
     As shown in  FIG.  12 A , in a direction of a current flow of a discharge stage  1 , the first switch  1132  is disconnected, the second switch  1133  is closed, and the capacitor unit  111  discharges the first inductor  1131  as a power supply. At this time, one or certain laser emitters do not need to emit light or need to reduce the luminous intensity, and the fully charged capacitor unit  111  releases a subnet of energy back to the first inductor  1131  to save energy. As shown in  FIG.  12 B , the horizontal axis is time. The upper curve is the curve of the current of the first inductor  1131  varied with time, and the lower curve is the curve of the output voltage HV 1  of the power supply unit  11  varied with time. The first switch  1132  is disconnected and the second switch  1133  is closed. The capacitor unit  111  and the first inductor  1131  form resonance. The voltage of the capacitor unit  111  resonantly decreases. After the voltage drops to a target voltage, the second switch  1133  is disconnected. 
     As shown in  FIG.  13 A , in a direction of a current flow of a discharge stage  2 , the first switch  1132  is closed, the second switch  1133  is disconnected, and the preparatory voltage source  112  and the first inductor  1131  form the discharging loop. As shown in  FIG.  13 B , the horizontal axis is time. The upper curve is the curve of the current of the first inductor  1131  varied with time, and the lower curve is the curve of the output voltage HV 1  of the power supply unit  11  varied with time. The current of the first inductor decreases according to a slope of −VBASE/L. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  9 C , the power supply unit  10  further includes a reset switch  1134 , where the reset first switch  1134  is connected between the preparatory voltage source  112  and the capacitor unit  111 , and is configured to reduce the output voltage HV 1  back to the preparatory voltage VBASE. Preferably, the first switch  1132 , the second switch  1133 , and the reset switch  1134  include one or more of a GaN switch and a CMOS switch. The reset switch  1134  may be built with discrete devices such as a MOS transistor and a GaN switch, or with an activating switch. 
     As shown in  FIG.  14 A , the reset switch  1134  is closed and the first inductor  1131  is reset, to prevent a parasitic capacitor of the first inductor  1131  and the first switch  1132  from resonating again. The resonance affects the capacitor unit  111  and the next charge process. As shown in  FIG.  14 B , the horizontal axis is time. The upper curve is the curve of the current of the first inductor  1131  varied with time, and the lower curve is the curve of the output voltage HV 1  of the power supply unit  11  varied with time. The output voltage HV 1  quickly boosts to the preparatory voltage VBASE. 
     It can be seen from the foregoing plurality of embodiments that the fast bus power supply system provided in the present disclosure requires three control signals, that is, a low-side driving signal controlling the first switch  1132  (DRVL_HV 1  shown in  FIG.  9 C ), a high-side driving signal controlling the second switch  1133  (DRVH_HV 1  shown in  FIG.  9 C ), and a reset signal controlling the reset switch  1134  (DRVRST_HV 1  shown in  FIG.  9 C ). The proper coordination of the three signals can achieve the adjustment time of &lt;1 us, thus the light intensity of the laser emitter can be adjusted pixel by pixel. 
     According to an exemplary embodiment of the present disclosure, the present disclosure further provides a control unit for controlling the power supply unit  11  as described above, where a high-voltage generation unit  113  includes a first switch  1132 , a second switch  1133 , and a reset switch  1134 , and the control unit includes: generating a voltage control signal according to a time sequence of light emission of laser emitters, and outputting the voltage control signals (that is, DRVL_HV 1 , DRVH_HV 1 , or DRVRST_HV 1  shown in  FIG.  9 C ) to control electrodes of the first switch  1132 , the second switch  1133 , and the reset switch  1134  respectively, to control the high-voltage generation unit  113  to output an output voltage higher than a preparatory voltage, and control a capacitor unit  111  and the high-voltage generation unit  113  to cooperatively adjust the output voltage through charge and discharge processes. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  4 A , the present disclosure further provides an emitting apparatus  10  of a lidar, including: a plurality of power supply units  11  as described above, configured to receive a preparatory voltage and output a high voltage, where at least two power supply units  11  output the high voltage at relatively different times, and the high voltage is a voltage higher than the preparatory voltage; a laser emitter unit  12 , including a plurality of laser emitters  121 , where an anode of each laser emitter  121  is connected to an output end of one of the power supply units  11 , so that at least two of the laser emitters  121  are connected to different power supply units  11 ; and at least one switching device  13 , where other ends of a subset of laser emitters  121  that do not share the voltage are connected to one of the switching devices  13 , and the switching device  13  is configured to control a connection state of a current loop formed by the corresponding power supply unit  11 , the laser emitter  121  connected to the switching device  13 , and the ground. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  15   , the present disclosure further provides a method  30  for controlling a laser emitter to emit light by using the power supply unit  11  as described above, including the following steps: 
     Step S 301 : Output a preparatory voltage through the preparatory voltage source  112 . 
     Step S 302 : Generate an output voltage higher than the preparatory voltage through a high-voltage generation unit  113 . 
     Step S 303 : Cooperatively adjust the output voltage through charge and discharge processes of a capacitor unit  111  and the high-voltage generation unit  113 . 
     According to an exemplary embodiment of the present disclosure, the high-voltage generation unit  113  includes: a first inductor  1131 , a first end of which is coupled to the preparatory voltage source  112 , a first switch  1132  having a first end coupled to a second end of the first inductor  1131  and a second end connected to ground, and a second switch  1133  having a first end coupled to the second end of the first inductor  1131  and a second end coupled to the capacitor unit  111 . The method  30  further includes: 
     outputting electrical energy from the preparatory voltage source  112  through the first inductor  1131 ; 
     causing the preparatory voltage source  112  and the first inductor  1131  to form a charging loop by closing the first switch  1132  and opening the second switch  1133 , thus charging the first inductor  1131  by the preparatory voltage source  112 ; and 
     causing the preparatory voltage source  112  and the first inductor  1131  to form a discharging loop by disconnecting the first switch  1132  and closing the second switch  1133 , thus charging the capacitor unit  111  by the preparatory voltage source  112  and the first inductor  1131 , so that the output voltage is higher than the preparatory voltage. 
     According to an exemplary embodiment of the present disclosure, the method  30  further includes: 
     causing the capacitor unit  111  discharge by disconnecting the first switch  1132  and closing the second switch  1133 , where the first inductor  1131  receives electrical energy from the capacitor unit  111  to reduce the output voltage. 
     According to an exemplary embodiment of the present disclosure, the power supply unit  11  further includes a reset switch  1134 , where the reset switch  1134  is connected between the preparatory voltage source  112  and the capacitor unit  111 . The method  30  further includes: 
     reducing the output voltage back to the preparatory voltage through the reset switch  1134 . 
     An exemplary embodiment of the present disclosure provides a power supply unit including an LC resonant circuit. Due to the characteristics of the LC resonant circuit, a charge-discharge speed of the power supply unit for a mounted capacitor is greatly improved. Compared with a solution of a feedback circuit used in another embodiment, the speed is increased by a thousand times. 
     To reflect the effect of the HV supply circuit in this application,  FIG.  9 A  shows a structure of a conventional HV supply circuit. The power supply in  FIG.  9 A  outputs a high voltage HV which is compared with a reference voltage Vref after sampled, to obtain an error signal. A control signal u is generated through a PID controller. A PWM comparator compares the u with a sawtooth wave with a fixed frequency (a specific value is related to a system using the HV circuit), and outputs a group of control pulses to control a connection state of a power switch, so as to maintain the relative stability of the output voltage. From the perspective of the circuit structure, there are relatively many components in the whole circuit. In addition, because the operating process requires negative feedback, a switching speed of the HV is also relatively slow.  FIG.  9 B  is a simulation diagram of operating by using the power supply in  FIG.  9 A  to supply HV. Compared  FIG.  9 B  with  FIG.  10 B , it takes 0.9 ms=1.9 ms−1 ms to output the high voltage HV 1  of 30 V in  FIG.  9 B , but it takes less than 0.2 μs≈0.8 μs−0.6 μs to output the high voltage HV 1  of 30 V in  FIG.  10 B . The speed is increased by a thousand times. Therefore, with the power supply unit  11  in this application, the HV can be output quickly, and the HV can also be switched quickly, so that the light intensity of a plurality of laser emitters of the lidar can be adjusted more quickly to match with an external obstacle situation or a scenario of use, thereby improving accuracy of point cloud detection. 
     Third Aspect 
       FIG.  18    shows an embodiment of a driving apparatus  100  of a lidar with four fast buses. The driving apparatus  100  includes four buses, that is, HVBUSA, HVBUSB, HVBUSC and HVBUSD. Two laser emitters are mounted on each bus. Laser emitter LAS 1  and laser emitter LAS 2  are mounted on the bus HVBUSA. Laser emitter LAS 3  and laser emitter LAS 4  are mounted on the bus HVBUSB. Laser emitter LAS 5  and laser emitter LAS 6  are mounted on the bus HVBUSC. Laser emitter LAS 7  and laser emitter LAS 8  are mounted on the bus HVBUSD. The four laser emitters mounted on different buses share a GaN switching device. Cathodes of the laser emitter LAS 1 , laser emitter LAS 3 , laser emitter LAS 5 , and laser emitter LAS 7  are jointly coupled to the GaN switching device GaN 1 . Cathodes of the laser emitter LAS 2 , laser emitter LAS 4 , laser emitter LAS 6 , and laser emitter LAS 8  are jointly coupled to the GaN switching device GaN 2 . Through activating of the GaN switching devices GaN 1  and GaN 2 , the corresponding laser emitter emits light. Each fast bus includes an energy storage unit, as the capacitors C 1 -C 4  shown in the figure. The energy storage unit on the bus HVBUSA is the C 1 , the energy storage unit on the bus HVBUSB is the C 2 , the energy storage unit on the bus HVBUSC_E is the C 3 , and the energy storage unit on the bus HVBUSD is the C 4 . 
     A switching loss and a charge loss generated by a multi-bus driving apparatus in the operating process are further described below with an embodiment of a four-bus driving apparatus. 
     As shown in  FIG.  18   , it may be assumed that in detection, a plurality of laser emitters of the lidar do not emit light in parallel. In other words, part of the plurality of laser emitters can emit light in parallel, but not all of them emit light at the same time. In this embodiment, an example in which the laser emitters emit light one by one is introduced. The GaN switching device GaN 1  is closed, the bus HVBUSA outputs a high voltage to charge the C 1 , and then discharges through the energy storage unit C 1 , so that the laser emitter LAS 1  mounted on the bus HVBUSA emits a laser pulse. After the laser emitter LAS 1  completes operating, the bus HVBUSA is switched to the bus HVBUSB. The GaN switching device GaN 1  is closed again. At this time, the bus HVBUSB outputs the high voltage to charge the C 3 , and the laser emitter LAS 3  mounted on the bus HVBUSB emits the laser pulse through discharging of the energy storage unit C 3 . Before the GaN switching device GaN 1  is closed again, it is necessary to empty the remaining energy in the energy storage unit C 1  on the bus HVBUSA. Otherwise, after the GaN switching device GaN 1  is closed again, the laser emitter LAS 1  emits the laser pulse again, which affects the detection of the laser emitter LAS 3 . Moreover, the one-by-one activating of the laser emitters is also affected. In detail, the laser emitter LAS 1  emits the laser pulse again through the remaining energy on the energy storage unit C 1 . Although the pulse energy is less than pulse energy emitted by the laser emitter LAS 1  during detection, serious interference is still caused to the detection of the laser emitter LAS 3 . Therefore, the remaining energy in the energy storage unit on the last operating bus may be emptied in each switching. Because a quantity of electricity stored in the capacitor meets Q=0.5 CV 2 , a total loss generated by the switching of the bus is: 
       switching loss=0.5 f   bus   CV   2   Formula 1,
 
     where f bus  is a bus switching frequency, C is a capacitance value of the energy storage unit, and V is a voltage on the energy storage unit. V is approximately considered to be an output voltage of the bus, and is approximately HV. 
     Therefore, to reduce the switching loss, the output voltage of the bus needs to be set to be relatively low and the capacitance value of the energy storage unit needs to be set to be relatively small. However, reducing the capacitance value of the energy storage unit causes an increase in the charge loss on the bus. The charge loss generated by a multi-bus apparatus in the operating process is described below. 
     As shown in  FIG.  18   , it may be assumed that the plurality of laser emitters of the lidar emit light one by one (in other embodiments, the laser emitters may not emit light at the same time, that is, a subnet of the plurality of laser emitters emit light at the same time), and emit three laser pulses in each (one detection refers to obtaining a distance value of one point of the external obstacle) detection. The GaN switching device GaN 1  is closed, and is provided with energy through the energy storage unit C 1 . The laser emitter LAS 1  mounted on the bus HVBUSA emits the first laser pulse. After that, the energy storage unit C 1  provides energy for the laser emitter LAS 1  again, and the laser emitter LAS 1  emits the second laser pulse . . . . Suppose that the voltage on the energy storage unit C 1  after charged is V, and the voltage on the energy storage unit C 1  after discharged (corresponding to emitting a single pulse) is V′, a voltage drop during each discharge process is ΔV=V−V′.  FIG.  19    shows a change of the voltage on the energy storage unit C 1  during the discharge-charge process: Before discharge, the voltage on the energy storage unit C 1  is V. The discharge process starts at the time t1 to provide energy for the laser emitter to emit pulse. The discharge process ends at the time t2. After the discharge process, the voltage on the energy storage unit C 1  is V′. In an embodiment of the present disclosure, the energy storage unit can be charged from the time t2. After the charging is completed, the voltage on the energy storage unit C 1  reaches V again or is close to V. In another embodiment of the present disclosure, the energy storage unit C 1  completes the power supply at the time t3. That is, the electricity on the energy storage unit C 1  is discharged, and then the energy storage unit C 1  is recharged. It is easy for a person skilled in the art to understand that the voltage reached by recharging the energy storage unit C 1  may be adjusted according to the detection demand, and may be the same as or different from the voltage V required for the last detection. 
     The present disclosure uses a double-edge charge solution, and the charge loss generated under the charge solution is calculated below. 
     It is advisable to suppose that the energy of emitting the laser pulse in one detection is ΔE, and photoelectric conversion efficiency is PCE. An energy difference is calculated according to the voltage drop of the energy storage unit C 1  before and after the discharge: 
     
       
         
           
             
               
                 
                   
                     
                       0.5 
                       
                         
                           C 
                           ⁢ 
                           V 
                         
                         2 
                       
                     
                     - 
                     
                       0.5 
                       
                         
                           C 
                           ⁢ 
                           V 
                         
                         
                           ′ 
                           ⁢ 
                           2 
                         
                       
                     
                   
                   = 
                   
                     
                       
                         
                           C 
                           ⁢ 
                           V 
                         
                         ⁢ 
                         Δ 
                         ⁢ 
                         V 
                       
                       - 
                       
                         0.5 
                         C 
                         ⁢ 
                         Δ 
                         ⁢ 
                         
                           V 
                           2 
                         
                       
                     
                     = 
                     
                       
                         Δ 
                         ⁢ 
                         E 
                       
                       PCE 
                     
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                       
                   2 
                 
               
             
           
         
       
     
     In a case that ΔE/PCE is set, the calculated ΔV is inversely proportional to the capacitance value C of the energy storage unit. 
     The energy storage unit C 1  is charged through the bus HVBUSA. After the charging is completed, the voltage on the energy storage unit C 1  reaches V again. The charge is usually 
     completed through an RC loop. Therefore, the charge loss of the bus is mainly determined by the discharge depth. That is: 
     
       
         
           
             
               
                 
                   
                     
                       
                         
                             
                           
                             
                               
                                 charge 
                                 ⁢ 
                                    
                                 loss 
                               
                               = 
                             
                           
                         
                       
                       
                         ∫ 
                         
                           
                             
                               I 
                               2 
                             
                             ( 
                             t 
                             ) 
                           
                           ⁢ 
                           Rdt 
                         
                       
                     
                     = 
                     
                       
                         ∫ 
                         
                           
                             
                               ( 
                               
                                 
                                   ΔV 
                                   R 
                                 
                                 ⁢ 
                                 
                                   e 
                                   
                                     - 
                                     
                                       t 
                                       RC 
                                     
                                   
                                 
                               
                               ) 
                             
                             2 
                           
                           ⁢ 
                           Rdt 
                         
                       
                       = 
                       
                         0.5 
                         C 
                         ⁢ 
                         
                           ΔV 
                           2 
                         
                       
                     
                   
                   , 
                 
               
               
                 
                   Formula 
                   ⁢ 
                       
                   3 
                 
               
             
           
         
       
     
     where R is equivalent resistance of the first switch Q 1 /Q 2 /Q 3 /Q 4  shown in  FIG.  18   , and I is a current flowing through it. According to Formula 2, it is known from the foregoing analysis that the discharge depth ΔV is inversely proportional to the capacitance value C of the energy storage unit. According to Formula 3, it may be learned that the charge loss of the bus is inversely proportional to the capacitance value C of the energy storage unit. 
     In summary, the switching loss and the charge loss generated by the multi-bus driving apparatus in the operating process are: 
       total loss=0.5 f   bus   CV   2 +0.5 f   pulse   CΔV   2   Formula 4,
 
     where f pulse  is a frequency of emitted laser pulse. 
     A 128-line mechanical rotating radar is used as an example. If there are eight HVBUS in total, horizontal angular resolution is 0.1°, a rotational speed is 20 HZ,  9  channels emit light at the same time, each point cloud has 2 pulses, light energy of each pulse is 6 ns*35 W, an output voltage of the bus is V=16 V, and photoelectric conversion efficiency is PCE=20%. f bus  is a switching frequency of the bus and f pulse  is a pulse frequency. 
     
       
         
           
             
               
                 
                   
                     
                       
                         
                           f 
                           bus 
                         
                         = 
                         
                           
                             6 
                             * 
                             20 
                             * 
                             
                               ( 
                               
                                 360 
                                 0.1 
                               
                               ) 
                             
                           
                           = 
                           
                             432 
                             ⁢ 
                                
                             kHz 
                           
                         
                       
                     
                   
                   
                     
                       
                         
                           f 
                           pulse 
                         
                         = 
                         
                           
                             
                               
                                 f 
                                 bus 
                               
                               / 
                               8 
                             
                             * 
                             16 
                             * 
                             2 
                           
                           = 
                           
                             0.432 
                                
                             MHz 
                               
                           
                         
                       
                     
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                       
                   5 
                 
               
             
           
         
       
     
     As shown in  FIG.  20   , the switching loss, pulse charge loss, and total loss of the multi-bus driving apparatus used for the 128-line mechanical radar in the operating process in a case of the capacitance values C of different energy storage units are solved. It can be learned from  FIG.  20    that with the increase of the capacitance value C, the switching loss of the bus increases linearly and the charge loss of the pulse decreases. However, a minimum value of the sum of the two still reaches 4 W, where a black horizontal line marks a bottom value. 
     Since the multi-bus driving apparatus includes a plurality of capacitors, which are relatively dispersed, it is difficult to reduce the charge loss. The present disclosure provides a driving apparatus of a lidar. The remaining electricity in the energy storage unit is transferred through an energy transfer unit, thereby reducing the switching loss without changing the capacitance value and the switching frequency. Therefore, the total loss (Formula 4) almost only includes the charge loss, which is related to a capacitance parameter of the energy storage unit. The charge loss can be further reduced by increasing the capacitance value. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  21   , the present disclosure provides a driving apparatus  100  of a lidar, configured to drive a laser emitter. A plurality of laser emitters operate in turns. The driving apparatus  100  includes a plurality of driving units  110 , such as  110 - 1 ,  110 - 2 , . . . ,  110 - n  shown in the figure, and an energy transfer unit  120 . 
     Each driving unit  110  includes at least one energy storage unit  111 , such as  111 - 1 ,  111 - 2 , . . . , and  111 - n  shown in  FIG.  21   , configured to provide energy for the corresponding laser emitter. 
     As shown in  FIG.  21   , the driving unit  110 - 1  supplies power for the corresponding laser emitter LAS 1  to emit light, and the provided energy is stored in the energy storage unit  111 - 1 . The laser emitter LAS 1  is discharged by the energy storage unit  111 - 1  during its operation. The laser emitter LAS 1  emits a laser pulse, the energy in the energy storage unit  111 - 1  is consumed and the voltage is reduced. Before the laser emitter LAS 1  emits light next time, the driving unit  110 - 1  receives a preparatory voltage through an external voltage source, and then generates a high voltage higher than the preparatory voltage through a high-voltage generation unit, to charge the energy storage unit  111 - 1 , so that the energy storage unit  111 - 1  stores sufficient energy again for the laser emitter LAS 1  to operate. If the laser emitter that emits light next time is mounted on another bus, for example, the laser emitter emitting light next time is the laser emitter LAS 2 , corresponding to the driving unit  110 - 2 , the remaining energy in the energy storage unit  111 - 1  can be emptied to prevent the laser emitter LAS 1  corresponding to the energy storage unit  111 - 1  from emitting light again when the laser emitter LAS 2  is activated, affecting the detection operate of the lidar and making each laser emitter fail to be individually addressable. 
     In addition, the driving units  110 - 1 ,  110 - 2 , . . . , and  110 - n  shown in  FIG.  21    all correspond to one laser emitter. It is easy for a person skilled in the art to understand that this is an equivalent graphical method. Each laser emitter may correspond to one or more driving units  110 , thereby overcoming the defect of insufficient switching speed between a plurality of pulses emitted by a laser emitter. 
     The energy transfer unit  120  is coupled between two driving units  110 - n  (n is a positive integer), and is configured to, after the currently operating driving unit  110 - n  completes driving to make the laser emitter connected to the currently operating driving unit  110 - n  to emit light, transfer the remaining energy in an energy storage unit  111 - m  (m is a positive integer) of the currently operating driving unit  110 - n  to an energy storage unit  111 - m  of the next operating driving unit  110 - n , to make the laser emitter connected to the next operating driving unit  110 - n  to emit light. It should be noted that the energy transfer unit  120  currently shown in  FIG.  21    is coupled between the adjacent driving units. A person skilled in the art can understand that this is just an example. In actual implementation, the energy transfer unit  120  can be connected between the driving units that are not physically directly adjacent, as long as there is a time sequence of light emission of the laser emitters connected by the energy transfer unit  120 . 
     As described above, after the laser emitter 1 completes the detection operate, the driving unit  110 - 1  is switched to the driving unit  110 - 2 . At this time, the remaining energy in the energy storage unit can be emptied. In the present disclosure, the remaining energy in the energy storage unit is transferred to the energy storage unit  111 - 2  through the energy transfer unit  120  coupled between the driving unit  110 - 1  and the driving units  110 - 2 . Based on the remaining energy transferred to the energy storage unit  111 - 2 , the driving unit  110 - 2  charges the energy storage unit  111 - 2  through the external voltage source, so that the energy storage unit  111 - 2  stores sufficient energy for the laser emitter LAS 2  to operate. The laser emitter LAS 2  is discharged by the energy storage unit  111 - 2  during its operation. The laser emitter LAS 2  emits the laser pulse. 
     It is easy for a person skilled in the art to understand that the energy transfer unit  120  in the present disclosure is coupled between two driving units  110 . A specific position of the energy transfer unit  120  is determined by an operating sequence of a plurality of driving units  110 , so that the energy transfer unit  120  can transfer the remaining energy according to the operating sequence of the plurality of driving units  110 . An arrangement mode of the energy transfer unit  120  is not limited to the situation shown in  FIG.  21   . 
     The multi-bus driving apparatus for a lidar provided in the present disclosure transfers the remaining energy in the energy storage unit corresponding to the currently operating laser emitter through the energy transfer unit, which avoids the switching loss caused by emptying the remaining energy in the energy storage unit. In addition, the transferred remaining energy is used by the energy storage unit corresponding to the next operating laser emitter, thereby further reducing the power consumption. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  22   , the present disclosure provides a four-bus driving apparatus for a lidar, where the lidar includes a plurality of laser emitters, the plurality of laser emitters emit light in turns, and an anode of each laser emitter is connected to an output end of one of a plurality of driving units.  FIG.  22    shows that the anode of each laser emitter is connected to one of a plurality of buses. The lidar further includes an energy transfer unit  120  and a GaN switching device, where the energy transfer unit  120  is connected between capacitors C 1  and C 2 , and configured to transfer the remaining energy in an energy storage unit C 1 /C 2  to an energy storage unit C 2 /C 1 . It should be noted that  FIG.  22    is only an example, which only directly shows an equivalent diagram of the energy transfer unit  120  connected between the capacitors C 1  and C 2  and in an operating state (directly connected to the capacitors C 1  and C 2 ). In fact, one or more switches can also be arranged on a circuit where the energy transfer unit  120  is connected between the capacitors C 1  and C 2 , to control whether the energy transfer unit  120  is operating and how long it is in the operating state. In addition, a person skilled in the art can understand that the similar energy transfer unit  120  may also be connected between other HVBUS buses. 
     For the GaN switching device, the cathodes of the laser emitters that do not share the driving unit are connected to one GaN switching device, which is configured to conduct or switching off a current loop formed by the corresponding driving unit, the laser emitter connected to the GaN switching device, and the ground, so as to make the laser emitter emit light or not emit light. 
     As shown in  FIG.  22   , a plurality of laser emitters LAS 1 -LAS 8  of the lidar emit light in turns (not representing a specific time sequence of light emission, but indicating that not all eight laser emitters emit light at the same time). If the laser emitter LAS 1  emits light first, and the laser emitter LAS 2  emits light later, it is advisable to suppose that the GaN switching device GaN 1  is closed, and the energy storage unit C 1  is charged. Energy is provided for the laser emitter through the energy storage unit C 1 . The laser emitter LAS 1  mounted on the bus HVBUSA emits the laser pulse. After the laser emitter LAS 1  completes operating, the bus HVBUSA is switched to the bus HVBUSB. The energy transfer unit  120  transfers the remaining energy in the energy storage unit C 1  to the energy storage unit C 2 . Later, similarly, the laser emitter LAS 2  emits the laser pulse by undergoing the charge-discharge process of the corresponding capacitor. 
     According to an exemplary embodiment of the present disclosure, in the multi-bus driving apparatus for a lidar, the driving unit further includes: 
     an external voltage source, configured to charge the energy storage unit. 
     As shown in  FIG.  22   , a plurality of driving units receive a preparatory voltage through the external voltage source HV, then generate a high voltage higher than the preparatory voltage through a high-voltage generation unit (not shown in the figure), and cause the energy storage unit to be charged with the high voltage. 
     The energy storage unit includes a capacitor, coupled between the external voltage source and the ground, and configured to discharge to a laser emitter on the activated current loop when the corresponding GaN switching device is closed, to drive the laser emitter to emit a single pulse. 
     As shown in  FIG.  22   , the energy storage unit includes the capacitor. The energy storage units on the buses HVBUSA, HVBUSB, HVBUSC, and HVBUSD are capacitors C 1 , C 2 , C 3 , and C 4  respectively. The capacitors C 1 , C 2 , C 3 , and C 4  are charged through the external voltage source HV, and discharge to the laser emitter on the activated current loop when the corresponding GaN switching device is closed. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  23   , in the multi-bus driving apparatus for a lidar, the energy transfer unit includes: 
     an inductor L, coupled between an output end of the currently operating driving unit and an output end of the next operating driving unit; and 
     switching assemblies K 1  and K 2 , connected in series to the inductor L, and configured to form resonance between the inductor L and the capacitor of the energy storage unit when the switching assemblies K 1  and K 2  are connected. 
     The inductor L shown in  FIG.  23    is coupled between the bus HV 1  and the bus HV 2 . Each bus corresponds to one driving unit, and each driving unit includes at least one energy storage unit. For example, the energy storage unit corresponding to the bus HV 1  is the capacitor C 1 , and the energy storage unit corresponding to the bus HV 2  is the capacitor C 2 . If the laser emitter mounted on the bus HV 1  operates first, the bus HV 1  outputs the high voltage to charge the energy storage unit C 1 , and the energy storage unit C 1  provides the energy required for the laser emitter mounted on the bus HV 1  to emit light. After the laser emitter mounted on the bus HV 1  completes emitting light, the energy on the energy storage unit C 1  is consumed, and the energy storage unit C 1  may still have a large amount of remaining energy. At this time, the switching assemblies K 1  and K 2  are connected, and the resonance is formed between the inductor L and the capacitors C 1  and C 2 . The remaining energy stored in the capacitor C 1  is transferred to the capacitor C 2 . After the transfer of the energy is completed, the switching assemblies K 1  and K 2  are disconnected. The laser emitter mounted on the bus HV 2  will operate. The high voltage may be output by the bus HV 2 . Based on the transferred remaining energy, the energy storage unit C 2  is charged by the bus HV 2  to reach an energy value required for the laser emitter mounted on the bus HV 2  to emit light. Or, after receiving the remaining energy from the capacitor C 1 , the capacitor C 2  can directly support the energy of the laser emitter to emit light at that time. At this time, it is not necessary to be charged additionally by the HV 2 . 
     According to an exemplary embodiment of the present disclosure, a conduction period of the switching assemblies K 1  and K 2  is determined according to a resonance period of the resonant circuit, so that during the conduction period of the switching assemblies K 1  and K 2 , all the remaining energy in the energy storage unit of the currently operating driving unit is transferred to the energy storage unit of the next operating driving unit. 
     After the switching assemblies K 1  and K 2  are connected, the capacitor C 1 , the capacitor C 2  and the inductor L form a resonant circuit. Within a period of t=π√{square root over ((C 1 +C 2 )L)}, the transfer of the remaining energy is completed. All the electricity on the capacitor C 1  is transferred to the capacitor C 2 . The voltage on the capacitor C 1  decreases and the voltage on the capacitor C 2  increases. At this time, the switching assemblies K 1  and K 2  are disconnected to prevent the electricity on the capacitor C 2  from returning to the capacitor C 1  through the resonant circuit. Since the current on the inductor L is close to zero when the switching assemblies K 1  and K 2  are connected/disconnected, there is almost no distribution parameter loss on the switching assemblies K 1  and K 2 . Preferably, by controlling internal resistance of the inductor L and the switching assemblies K 1  and K 2 , transfer efficiency of the remaining energy can reach more than 90%. 
     For example, suppose that the currently operating laser emitter is mounted on the bus HVBUS 1 , after the laser emitter completes emitting light, the remaining energy of the energy storage unit C 1  on the HVBUS 1  is 20. The next operating laser emitter is mounted on the bus HVBUS 2 . Before the next operating laser emitter emits light, the remaining energy of the energy storage unit C 1  is transferred to the energy storage unit C 2  through the inductor L. Suppose that conversion efficiency of the resonant circuit is 90%, initial energy on the energy storage unit C 2  is 18 after the transfer of the energy is completed. Suppose that the energy required for the two laser emitters operating successively to emit light is the same, it is sufficient to supplement energy  2  to the energy storage unit C 2  through the HVBUS 2 . In the conventional HVBUS multi-bus solution, the remaining energy of the energy storage unit C 1  on the HVBUS 1  needs to be completely emptied after the currently operating laser emitter has finished emitting light, which results in a huge loss. 
     In the present disclosure, the switching loss completely depends on the conversion efficiency of the resonant circuit, but is not positive correlation with the capacitance value of the energy storage unit. 
     In other words, the capacitance value is no longer a limiting factor for the switching loss during the operating process of the multi-bus driving apparatus. Further, the charge loss during the operating process of the multi-bus driving apparatus can be reduced by using a capacitor with a large capacitance value as the energy storage unit. In the foregoing examples, in the total loss of the multi-bus driving apparatus of the 128-line lidar, if a capacitor of 200 nf is selected, the total loss is reduced to 0.4+3.8*0.1=0.78 W. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  24   , the inductor L is coupled between the bus HV 1  and the bus HV 2 . The bus HV 1  and the bus HV 2  correspond to a driving unit respectively, and each driving unit includes at least one energy storage unit. The energy storage unit on the bus HV 1  is the capacitor C 1 , and the energy storage unit on the bus HV 2  is the capacitor C 2 . The switching in two directions, that is, switching from the bus HV 1  to the bus HV 2 , or from the bus HV 2  to the bus HV 1 , shares one switching assembly. The switching assembly is connected in series to the inductor L, and configured to form resonance between the inductor L and the capacitors C 1  and C 2  of the energy storage unit when the switching assembly is connected. 
     As shown in  FIG.  24   , when the NMOS switches Q 1  and Q 4  are connected, gates of the PMOS switches Q 2 , Q 3 , Q 5 , and Q 6  are pulled down, thereby achieving bidirectional conduction. When the NMOS switches Q 1  and Q 4  are turned off, the gates of the PMOS switches Q 2 , Q 3 , Q 5 , and Q 6  are reset by resistance, and therefore turned off. 
     When the laser emitter mounted on the bus HV 1  operates first, the bus HV 1  outputs the high voltage to charge the energy storage unit C 1 , and the energy storage unit C 1  provides the energy required for the laser emitter mounted on the bus HV 1  to emit light. After the laser emitter mounted on the bus HV 1  completes emitting light, the energy on the energy storage unit C 1  is consumed, but the energy storage unit C 1  still has a large amount of remaining energy. The energy on the energy storage unit C 2  is zero. At this time, the NMOS switches Q 1  and Q 4  are connected, and the gates of the PMOS switches Q 2 , Q 3 , Q 5 , and Q 6  are pulled down, thereby conducting the resonant circuit. The resonance is formed between the inductor L and the capacitors C 1  and C 2 , Transferring the remaining energy stored in the capacitor C 1  to the capacitor C 2 . After the transfer of the energy is completed, the NMOS switches Q 1  and Q 4  are turned off, and the gates of the PMOS switches Q 2 , Q 3 , Q 5 , and Q 6  are reset by resistance, and therefore turned off. The laser emitter mounted on the bus HV 2  operates. The bus HV 2  outputs the high voltage. Based on the transferred remaining energy, the energy storage unit C 2  is charged by the bus HV 2  to reach the energy value required for the laser emitter mounted on the bus HV 2  to emit light 
     When the laser emitter mounted on the bus HV 2  operates first, the bus HV 2  outputs the high voltage to charge the energy storage unit C 2 , and the energy storage unit C 2  provides the energy required for the laser emitter mounted on the bus HV 2  to emit light. After the laser emitter mounted on the bus HV 2  completes emitting light, the energy on the energy storage unit C 2  is consumed, but the energy storage unit C 2  still has a large amount of remaining energy. The energy on the energy storage unit C 1  is zero. At this time, the NMOS switches Q 1  and Q 4  are connected, and the gates of the PMOS switches Q 2 , Q 3 , Q 5  and Q 6  are pulled down, thereby conducting the resonant circuit. The resonance is formed between the inductor L and the capacitors C 1  and C 2 , transferring the remaining energy stored in the capacitor C 2  to the capacitor C 1 . After the transfer of the energy is completed, the NMOS switches Q 1  and Q 4  are turned off, and the gates of the PMOS switches Q 2 , Q 3 , Q 5  and Q 6  are reset by resistance, and therefore turned off. The laser emitter mounted on the bus HV 1  operates. The bus HV 1  outputs the high voltage. Based on the transferred remaining energy, the energy storage unit C 1  is charged by the bus HV 1  to reach the energy value required for the laser emitter mounted on the bus HV 1  to emit light 
     This embodiment provides an energy transfer unit of bidirectional conduction. The direction and order of activating can match with the time sequence of light emission of the laser emitters. For example, in a detection period, the laser emitter mounted on the bus HV 1  emits light first, and the laser emitter mounted on the bus HV 2  emits light later. In another detection period, the laser emitter mounted on the bus HV 2  emits light first, and the laser emitter mounted on the bus HV 1  emits light later. In the multi-line lidar, a plurality of laser emitters emit light in turns. In other words, all the laser emitters of the lidar do not emit light at the same time. The opposite of turns is that all the laser emitters emit light at the same time, and the laser emitters that emit light in adjacent time sequences are physically separated from each other as far as possible to reduce crosstalk. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  25   , the energy transfer unit further includes: 
     a diode, configured to be connected in series to the inductor and the switching assembly, where a conduction direction of the diode is determined according to the operating sequence of the two driving units, that is, to coordinate with the time sequence of light emission of the laser emitters. 
     As shown in  FIG.  25   , the energy transfer unit further includes a diode SD and a bidirectional analog switching SW. The inductor L is coupled between the bus HV 1  and the bus HV 2 . Each bus corresponds to a driving unit, and each driving unit includes at least one energy storage unit. For example, the energy storage unit on the bus HV 1  is the capacitor C 1 , and the energy storage unit on the bus HV 2  is the capacitor C 2 . The laser emitter mounted on the bus HV 1  operates first. The bus HV 1  outputs the high voltage to charge the energy storage unit C 1 , and the energy storage unit C 1  provides the energy required for the laser emitter mounted on the bus HV 1  to emit light. After the laser emitter mounted on the bus HV 1  completes emitting light, the energy on the energy storage unit C 1  is consumed, but the energy storage unit C 1  still has a large amount of remaining energy. At this time, the bidirectional analog switching SW is closed. The resonance is formed between the inductor L and the capacitors C 1  and C 2 . The remaining energy stored in the capacitor C 1  is transferred to the capacitor C 2 . After the transfer of the energy is completed, the bidirectional analog switching SW is disconnected. The laser emitter mounted on the bus HV 2  operates. The bus HV 2  outputs the high voltage. Based on the transferred remaining energy, the energy storage unit C 2  is charged by the bus HV 2  to reach the energy value required for the laser emitter mounted on the bus HV 2  to emit light 
     If the laser emitter mounted on the bus HV 2  operates first, the bus HV 2  outputs the high voltage to charge the energy storage unit C 2 , and the energy storage unit C 2  provides the energy required for the laser emitter mounted on the bus HV 2  to emit light. After the laser emitter mounted on the bus HV 2  completes emitting light, the energy on the energy storage unit C 2  is consumed, but the energy storage unit C 2  still has a large amount of remaining energy. At this time, even if the bidirectional analog switching SW is closed, due to unidirectionality of the diode SD, the resonance cannot be formed between the inductor L and the capacitors C 1  and C 2 , thus the remaining energy stored in the capacitor C 2  cannot be transferred to the capacitor C 1 . 
     This embodiment provides an energy transfer unit of unidirectional conduction. The conduction direction matches with the operating sequence of the laser emitters. For example, in each detection period, the laser emitter mounted on the bus HV 1  emits light first, and the laser emitter mounted on the bus HV 2  emits light later. This embodiment is applicable to a time sequence of light emission of a plurality of laser emitters of a lidar being a loop, and also applicable to a lidar in which a plurality of laser emitters are grouped, the laser emitters in each group emit light at the same time, and the detection is performed group by group. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  26   , the driving apparatus includes two energy transfer units, where 
     each energy transfer unit includes a diode and a switching assembly, respectively connected in series to the inductor, coupled between two driving units, and configured to transfer the remaining energy from opposite directions respectively. 
     As shown in  FIG.  26   , an energy transfer unit  120 - 1  includes a diode SD- 1  and a switching assembly SW- 1 , and an energy transfer unit  120 - 2  includes a diode SD- 2  and a switching assembly SW- 2 , which are respectively connected in series to the inductor L and coupled between the bus HV 1  and the bus HV 2 . Each bus corresponds to one driving unit, and each driving unit includes at least one energy storage unit. For example, the energy storage unit on the bus HV 1  is the capacitor C 1 , and the energy storage unit on the bus HV 2  is the capacitor C 2 . The laser emitter mounted on the bus HV 1  operates first. The bus HV 1  outputs the high voltage to charge the energy storage unit C 1 , and the energy storage unit C 1  provides the energy required for the laser emitter mounted on the bus HV 1  to emit light. After the laser emitter mounted on the bus HV 1  completes emitting light, the energy on the energy storage unit C 1  is consumed, but the energy storage unit C 1  still has a large amount of remaining energy. At this time, the switching assembly SW- 1  is connected, and the resonance is formed between the inductor L and the capacitors C 1  and C 2 . The remaining energy stored in the capacitor C 1  is transferred to the capacitor C 2 . After the transfer of the energy is completed, the switching assembly SW- 1  is disconnected. 
     After that, the laser emitter mounted on the bus HV 2  operates. The bus HV 2  outputs the high voltage. Based on the transferred remaining energy, the energy storage unit C 2  is charged by the bus HV 2  to reach the energy value required for the laser emitter mounted on the bus HV 2  to emit light After the laser emitter mounted on the bus HV 2  completes emitting light, the energy on the energy storage unit C 2  is consumed, but the energy storage unit C 2  still has a large amount of remaining energy. At this time, the switching assembly SW- 2  is connected, and the resonance is formed between the inductor L and the capacitors C 1  and C 2 . The remaining energy stored in the capacitor C 2  is transferred to the capacitor C 1 . After the transfer of the energy is completed, the switching assembly SW- 2  is disconnected. The laser emitter mounted on the bus HV 1  operates again. The bus HV 1  outputs the high voltage. Based on the transferred remaining energy, the energy storage unit C 1  is charged by the bus HV 1  to reach the energy value required for the laser emitter mounted on the bus HV 1  to emit light 
     With the two energy transfer units provided in this embodiment, each energy transfer unit can transfer the remaining energy from one direction, and can cooperate with the time sequence of light emission of the laser emitters, thereby achieving energy transfer between specific energy storage units, so as to reduce power consumption and improve energy utilization. 
     It is easy for a person skilled in the art to understand that the switching assemblies SW- 1  and SW- 2  shown in  FIG.  26    are only an equivalent graphical method. When used in practical projects, one or more switching devices may be used, and a variety of switching devices such as an NMOS switch, a PMOS switch, a field effect transistor, and a digital switching may be used, which is not limited in the present disclosure. 
     According to an exemplary embodiment of the present disclosure, as shown in  FIG.  27   , in the eight-bus driving apparatus for a lidar, there are two energy transfer units between the corresponding two driving units, which are configured to transfer the remaining energy in the energy storage unit from opposite directions. The plurality of energy transfer units share the inductor. 
     For example, when the laser emitter mounted on the bus HV 1  operates first, the energy storage unit on the bus HV 1  provides energy for the laser emitter. After the laser emitter mounted on the bus HV 1  completes operating, the remaining energy in the energy storage unit on the bus HV 1  is transferred to the energy storage unit on the bus HV 2  along a route from the diode D 1  to the inductor L 1  to the inductor L 2  to the switching assembly K 2 . The conduction/disconnection period of the switching assembly K 2  is determined according to the resonance period of the resonant circuit, to complete the transfer of all the remaining energy. 
     Based on the transferred remaining energy, the bus HV 2  outputs the high voltage to charge the energy storage unit on the bus HV 2 . The laser emitter mounted on the bus HV 2  operates, and the energy storage unit on the bus HV 2  provides energy for the laser emitter. After the laser emitter mounted on the bus HV 2  completes operating, the remaining energy in the energy storage unit on the bus HV 2  is transferred to the energy storage unit on the bus HV 3  along a route from the diode D 2  to the inductor L 2  to the inductor L 1  to the switching assembly K 3 . The conduction/disconnection period of the switching assembly K 3  is determined according to the resonance period of the resonant circuit, to complete the transfer of all the remaining energy. 
     Based on the transferred remaining energy, the bus HV 3  outputs the high voltage to charge the energy storage unit on the bus HV 3 . The laser emitter mounted on the bus HV 3  operates again, and the energy storage unit on the bus HV 3  provides energy for the laser emitter. After the laser emitter mounted on the bus HV 3  completes operating, the remaining energy in the energy storage unit on the bus HV 3  is transferred to the energy storage unit on the bus HV 4  along a route from the diode D 3  to the inductor L 1  to the inductor L 2  to the switching assembly K 4 . The conduction/disconnection period of the switching assembly K 4  is determined according to the resonance period of the resonant circuit, to complete the transfer of all the remaining energy. 
     Based on the transferred remaining energy, the bus HV 4  outputs the high voltage to charge the energy storage unit on the bus HV 4 . The laser emitter mounted on the bus HV 4  operates again, and the energy storage unit on the bus HV 4  provides energy for the laser emitter. After the laser emitter mounted on the bus HV 4  completes operating, the remaining energy in the energy storage unit on the bus HV 4  is transferred to the energy storage unit on the bus HV 5  along a route from the diode D 4  to the inductor L 2  to the inductor L 1  to the switching assembly K 5 . The conduction/disconnection period of the switching assembly K 5  is determined according to the resonance period of the resonant circuit, to complete the transfer of all or at least part of the remaining energy. 
     By analogy, the remaining energy in the energy storage unit of the bus HV 5  can be transferred to the energy storage unit of the bus HV 6 , HV 2 , HV 4 , or HV 8 . The remaining energy in the energy storage unit of the bus HV 6  can be transferred to the energy storage unit of the bus HV 7 , HV 1 , HV 3 , or HV 5 . The remaining energy in the energy storage unit of the bus HV 7  can be transferred to the energy storage unit of the bus HV 8 , HV 2 , HV 4 , or HV 6 . The transfer direction is controlled by the conduction/disconnection time sequence of the switching assemblies, equivalent to switching the remaining energy between the energy storage units of two groups of driving units, which is determined by the order of the light emission of a plurality of laser emitters of the lidar, or the switching order of the energy transfer is matched with the time sequence of the light emission of the laser emitters. For example, the order of the light emission of a plurality of laser emitters of a lidar is as follows: One or more laser emitters mounted on the bus HV 1  emit light first, then one or more laser emitters mounted on the bus HV 2  emit light, and next one or more laser emitters mounted on the bus HV 3  emit light . . . . The order of the light emission of a plurality of laser emitters determines the order of power supply of a plurality of driving units, thereby determining the transfer order of the remaining energy. 
     It is easy for a person skilled in the art to understand that the order of the light emission of a plurality of laser emitters mentioned above is only an example. In practical projects, different orders of the light emission of the laser emitters may be set. For example, one or more laser emitters mounted on the bus HV 1  emit light first, then one or more laser emitters mounted on the bus HV 2  emit light, and next one or more laser emitters mounted on the bus HV 5  emit light . . . . The operating sequence of the buses is set according to the order of the light emission of the laser emitters. For example, the bus HV 1  operates first, then the bus HV 2  operates, and next the bus HV 5  operates . . . . Subsequently, the transfer order of the remaining energy is set according to the operating sequence of the buses, and the transfer order is implemented by setting the conduction/disconnection period of the switching assemblies. 
     In this embodiment, two energy transfer units are arranged between the corresponding two driving units, the remaining energy in the energy storage unit is transferred from opposite directions, and the plurality of energy transfer units share the inductor, which achieves the switching of the remaining energy between the two groups of driving units, thereby ensuring the time sequence of the light emission of the plurality of laser emitters of the lidar, and reducing the switching loss. 
     The multi-bus driving apparatus for a lidar provided in the present disclosure can effectively reduce the switching loss of the multi-bus driving apparatus in the operating process. Since the switching frequency of the bus is far lower than the pulse frequency, the energy transfer unit may be arranged outside an emitting circuit board to reduce the wiring burden of the emitting circuit board. 
     According to an exemplary embodiment of the present disclosure, in the multi-bus driving apparatus for a lidar, the plurality of driving units output the same or different driving voltages, and the remaining energy includes: the remaining electricity in the energy storage unit after the laser emitter corresponding to the driving unit emits a laser pulse. 
     According to an exemplary embodiment of the present disclosure, the present disclosure further provides a method for driving a lidar by using the driving apparatus as described above, including step S 101  and step S 102 . 
     Step S 101 : Provide energy for the current laser emitter that emits light through the energy storage unit. 
     A driving unit supplies power for the corresponding laser emitter to emit light, and the provided energy is stored in the energy storage unit. The laser emitter is discharged by the energy storage unit during its operation. The laser emitter emits a laser pulse. The energy in the energy storage unit is consumed and the voltage is reduced. Before the laser emitter emits light next time, the driving unit receives a preparatory voltage through an external voltage source, and then generates a high voltage higher than the preparatory voltage through a high-voltage generation unit, to charge the energy storage unit, so that the energy storage unit stores sufficient energy again for the laser emitter to operate. If the laser emitter that emits light next time is on another bus, and corresponds to another driving unit, the remaining energy in the energy storage unit can be emptied to prevent the laser emitter corresponding to the energy storage unit from emitting light again when another laser emitter is activated, which affects the implementation of the detection operate of the lidar or the activating function of a single laser emitter. 
     Step S 102 : Transfer the remaining energy in the energy storage unit to the energy storage unit corresponding to the next laser emitter that emits light through the energy transfer unit after the current laser emitter that emits light completes operate. 
     After the currently operating laser emitter that completes the detection operate, the current driving unit that supplies power is switched to the next driving unit that supplies power, to empty the remaining energy in the energy storage unit. In the present disclosure, the remaining energy in the energy storage unit of the driving unit that completes power supply is transferred to the energy storage unit of the next driving unit that supplies power through the energy transfer unit coupled between two driving units. Based on the transferred remaining energy, the next driving unit that supplies power receives the preparatory voltage through the external voltage source, and the high-voltage generation unit generates the high voltage higher than the preparatory voltage to charge the energy storage unit thereof, so that the energy storage unit thereof stores sufficient energy for the next operating laser emitter to emit light. Tthe laser emitter is discharged by the corresponding energy storage unit during its operation to emit the laser pulse. 
     According to an exemplary embodiment of the present disclosure, two energy transfer units are coupled between the two driving units. The method further includes: 
     transferring the remaining energy from opposite directions through the two energy transfer units. 
     With the two energy transfer units provided in this embodiment, each energy transfer unit can only transfer the remaining energy from one direction. Even if one energy transfer fails, the subsequent energy transfer is not affected continuously. Moreover, the use of the two energy transfer units effectively reduces a probability of circuit failure. In addition, by arranging the two energy transfer units between the two groups of driving units, the remaining energy can be switched between the two groups of driving units in coordination with a time sequence of light emission of the laser emitters, which ensures the time sequence of light emission of a plurality of laser emitters of the lidar, and reduces a switching loss. 
     According to an exemplary embodiment of the present disclosure, the lidar includes n laser emitters, where n≥32, and the plurality of laser emitters emit light one by one. The driving method further includes: 
     operating by the plurality of driving units one by one, to provide energy for the plurality of laser emitters; and 
     successively transferring the remaining energy between the plurality of driving units through the energy transfer unit. 
     In this embodiment, the plurality of laser emitters of the lidar emit light one by one for detection. That is, the time sequence of light emission of the plurality of laser emitters of the lidar is a loop. The remaining energy is successively transferred between the plurality of driving units through the energy transfer unit, so as to implement a time sequence of power supply corresponding to the plurality of driving units. 
     According to an exemplary embodiment of the present disclosure, the plurality of laser emitters emit light in groups, where each group includes at least one laser emitter. The driving method further includes: 
     operating in groups by the plurality of driving units, to provide energy for the plurality of laser emitters; and 
     transferring the remaining energy in the energy storage unit to the energy storage unit corresponding to any one of the plurality of laser emitters that emit light in the next group through the energy transfer unit after the current laser emitter that emits light completes operating. 
     For example, the plurality of laser emitters mounted on buses HV 1  and HV 3  first emit light, and then the plurality of laser emitters mounted on buses HV 8  and HV 13  emit light. After the detection of the plurality of laser emitters mounted on the buses HV 1  and HV 3  is completed, the remaining energy in the energy storage unit on the bus HV 1  can be transferred to the energy storage unit on the bus HV 8  through the energy transfer unit, or, the remaining energy in the energy storage unit on the bus HV 1  can be transferred to the energy storage unit on the bus HV 13  through the energy transfer unit. The transfer solution of the remaining energy in the energy storage unit on the bus HV 2  can be obtained in the same way. 
     According to an exemplary embodiment of the present disclosure, the driving unit further includes an external voltage source, and the energy storage unit includes a capacitor, coupled between the external voltage source and the ground. The method further includes: 
     charging the capacitor through the external voltage source; and 
     discharging to the laser emitter on the activated current loop through the capacitor, to drive the laser emitter to emit a single pulse. 
     According to an exemplary embodiment of the present disclosure, the energy transfer unit includes an inductor and a switching assembly connected in series, and is coupled between output ends of the two driving units. The method further includes: 
     forming resonance by the inductor and the capacitor when the switching assembly is connected. 
     An exemplary embodiment of the present disclosure provides a driving apparatus for a lidar. The remaining energy in the energy storage unit corresponding to the currently operating laser emitter is transferred through the energy transfer unit, which avoids the switching loss caused by emptying the remaining energy in the energy storage unit. In addition, the transferred remaining energy is used by the energy storage unit corresponding to the next operating laser emitter, thereby further reducing the power consumption. 
     The exemplary embodiment of the present disclosure reduces the switching loss without changing the capacitance value and the switching frequency. Therefore, the total loss in the bus driving apparatus almost only includes the charge loss, which is related to a capacitance parameter of the energy storage unit. The charge loss can be further reduced by increasing the capacitance value. 
     Finally, it should be noted that: the foregoing descriptions are merely exemplary embodiments of the present disclosure, but are not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the foregoing embodiments, for a person skilled in the art, modifications can still be made to the technical solutions recorded in the foregoing embodiments, or equivalent replacements can be made to some technical features in the technical solutions. Any modification, equivalent replacement, or improvement made and the like within the spirit and principle of the present disclosure shall fall within the protection scope of the present disclosure.