Patent Publication Number: US-2021184483-A1

Title: High-voltage driver switch system and switching method

Description:
CROSS-REFERENCE TO RELATED INVENTIONS 
     This invention is a US application which claims the priority of CN application Serial No. 201911279948.4, filed on Dec. 13, 2019, the disclosures of which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a high-voltage driver switch system and switching method. 
     BACKGROUND ART 
     Currently, as for gardening tools, power tools and so on, some of the internal motor drive controllers have fuses added to the main circuit thereof for protection, and some are not added, which will cause large problems during work, especially at the moment of startup. The impulse current is easy to affect the external battery pack and the electronic switch inside the controller, which reduces the service life of the battery pack and the electronic switch. 
     Moreover, when the machine is turned on for the first time, it is also prone to sparks, while when it is turned off, because the plug-in socket of the external battery pack and the driver inside the controller are directly connected through the fuse, in which the internal energy storage capacitor will still retain the power that is incompletely discharged for a period of time after shutting down, so that there is a risk of residual charge in the plug-in socket of the external battery pack. 
     In view of the above, there is a need to provide an improved switch system to solve the problem. 
     SUMMARY OF INVENTION 
     One objective of the present invention is to provide a high-voltage driver switch system, which can reduce the instantaneous current when powered-on, and avoid high current impact caused by charging the energy storage capacitor by the external battery pack directly. 
     In order to achieve the above object, the present invention provides a high-voltage driver switch system, including: a main control chip module and an energy storage capacitor connected with a battery pack, and a drive circuit module respectively connected with the main control chip module and the battery pack, a pre-charge circuit and a charge circuit both for charging the energy storage capacitor, the pre-charge circuit which includes a current limit resistor connected with the main control chip module to pre-charge the energy storage capacitor under the control of the main control chip module, the charge circuit connected with the main control chip module and having an electronic switch module which includes two ends connected respectively with the battery pack and the energy storage capacitor, the battery pack is able to charge the energy storage capacitor when the electronic switch module is switched on by the main control chip module, a first sampling circuit being provided between the electronic switch module and the battery pack and a second sampling circuit being provide between the electronic switch module and the drive circuit module, and feedback terminals of the first sampling circuit and the second sampling circuit both connected with the main control chip module. 
     As a further improvement of the invention, the pre-charge circuit further include a first switch tube, a PTC thermistor, a second switch tube, a rectifier tube, and in where the first switch tube is connected with the main control chip module, the second switch tube is connected with the first switch tube, and in where the PTC thermistor, the second switch tube, the rectifier tube and the current limit resistor connect in order, and in where the other end of the PTC thermistor connects with a positive output of the battery pack, and the other end of the current limit resistor connects with the positive electrode of the energy storage capacitor. 
     As a further improvement of the invention, the pre-charge circuit and the energy storage capacitor are connected in series and constitute an integral circuit. 
     As a further improvement of the invention, the pre-charge circuit is turned on by a single pulse sent from the main control chip module to charge the energy storage capacitor for the first time; and the main control chip module is not allowed to send the single pulse to the pre-charge circuit again after sending the single pulse. 
     As a further improvement of the invention, the charge circuit also includes a third switch tube connected with the electronic switch module, the third switch tube connected with the main control chip module to receive a control signal sent from the main control chip module so as to switch on or switch off the electronic switch module. 
     As a further improvement of the invention, the electronic switch module includes a control terminal connected to the third switch tube and a switch terminal electrically connected to the control terminal, and in where when the third switch tube is switched on, the control terminal forms an energized circuit to switch on the switch terminal, so that the battery pack, the switch terminal and the energy storage capacitor are electrically connected and the battery pack starts to charges the energy storage capacitor. 
     As a further improvement of the invention, the pre-charge circuit charges the energy storage capacitor for the first time after being turned on by a single pulse sent from the main control chip module, and when the main control chip module determines that voltage sampling values sampled respectively by the second sampling circuit and the first sampling circuit are the same, and a charging voltage of the energy storage capacitor is equal to a voltage of the battery pack, and the main control chip module sends a control signal to the third switch tube. 
     As a further improvement of the invention, the main control chip module is integrated with pre-programmed power-on sequential logic, power-off sequential logic and drive signal logic. 
     In order to achieve the object, the present invention also provides a switching method of a high-voltage driver switch system, the present invention provides a high-voltage driver switch system, including: a main control chip module and an energy storage capacitor connected with a battery pack, and a drive circuit module respectively connected with the main control chip module and the battery pack, a pre-charge circuit and a charge circuit both for charging the energy storage capacitor, the pre-charge circuit which includes a current limit resistor connected with the main control chip module to pre-charge the energy storage capacitor under the control of the main control chip module, the charge circuit connected with the main control chip module and having an electronic switch module which includes two ends connected respectively with the battery pack and the energy storage capacitor, the battery pack is able to charge the energy storage capacitor when the electronic switch module is switched on by the main control chip module, a first sampling circuit being provided between the electronic switch module and the battery pack and a second sampling circuit being provide between the electronic switch module and the drive circuit module, and feedback terminals of the first sampling circuit and the second sampling circuit both connected with the main control chip module, in where, the switching method of the high-voltage driver switch system includes a power-on method which mainly includes: 
     turning on the pre-charge circuit under the control of the main control chip module, charging the energy storage capacitor for the first time through the pre-charge circuit; 
     after the main control chip module determines that voltage sampling values sampled by the second sampling circuit and the first sampling circuit are the same, switching on the electronic switch module under the control of the main control chip module to turn on the charge circuit, charging the energy storage capacitor through the battery pack to enable the energy storage capacitor have enough power provided to the drive circuit module; 
     sending, by the main control chip module, a control command to the drive circuit module to make the drive circuit module work normally. 
     As a further improvement of the invention, the switching method of the high-voltage driver switch system further includes a power-off method which mainly includes: 
     turning off the drive circuit module under the control of the main control chip module; 
     switching off the electronic switch module of the charge circuit under the control of the main control chip module. 
     The beneficial effects of the present invention are: the high-voltage driver switch system of the present invention can first use the pre-charge circuit to pre-charge the energy storage capacitor, and then use the charge circuit to make the battery pack continue to charge the energy storage capacitor, so that the current limit resistor in the pre-charge circuit can be used to reduce the instantaneous start-up current, thereby avoiding a high current impact, which will burn the electronic switch module or the battery pack, caused by charging the energy storage capacitor by the external battery pack directly. 
     The above general description and the following detailed description are intended to be illustrative and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The sole FIGURE is a circuit principle diagram of a high-voltage driver switch system of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     The exemplary embodiment will be described in detail herein, and the embodiment is illustrated in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements. The embodiment described in the following exemplary embodiment does not represent all embodiments consistent with present invention. On the contrary, they are only examples of devices, systems, machines, and methods consistent with some aspects of the invention as detailed in the appended claims. 
     Reference will now be made to the drawing FIGURES to describe the embodiments of the present disclosure in detail. In the following description, the same drawing reference numerals are used for the same elements in different drawings. 
     As shown in the sole FIGURE, an embodiment of the present invention discloses a high-voltage driver switch system, used to solve the risk of large startup inrush current and residual charge on the plug-in socket when the circuit on the internal main circuit of the high-voltage driver is connected to the external battery pack. 
     The high-voltage driver switch system includes a main control chip module  30  and an energy storage capacitor C 1  which both connected to an external battery pack  10 , a drive circuit module  80  respectively connected to the main control chip module  30  and the battery pack  10 , and a pre-charging circuit and a charging circuit that can charge the energy storage capacitor C 1 . The main control chip module  30  is connected respectively with the battery pack  10 , the pre-charge circuit, the charge circuit, the drive circuit module  80 , a first sampling circuit  100  and a second sampling circuit  110 , to thereby control the pre-charge circuit to pre-charge the energy storage capacitor C 1 . After a certain period of pre-charging, that is, after determining that the voltage sampling values sampled by the first sampling circuit  100  and the second sampling circuit  110  are the same, the main control chip module  30  turns on the charge circuit to make the battery pack  10  continue to charge the energy capacitor C 1 . 
     The battery pack  10 , which is a detachable external battery pack, connected to an internal main circuit of the high-voltage driver, and used to supply power to the entire high-voltage driver switch system. The main control chip module  30  integrates functional programs such as pre-programmed power-on sequential logic, power-off sequential logic and drive signal logic and so on, so as to perform corresponding power-on control, shutdown control and drive control. 
     The drive circuit module  80  also connects with a motor  90  to control the motor  90  to star-up and shut-down. More specifically, the drive circuit module  80  includes a drive circuit and a plurality of power tubes. The drive circuit is connected with the main control chip module  30 , and the plurality of power tubes are respectively connected with the drive circuit and the motor  90 , so that when working, the main control module  30  sends control command to the drive circuit. The drive circuit controls the corresponding power tube to switch on or switch off according to the control command received, and then controls the motor  90  to run normally or stop running. 
     The pre-charge circuit includes a first switch tube  60 , a PTC thermistor, a second switch tube  50 , a rectifier tube D 1  and a current limit resistor R 1 . The first switch tube  60  is connected with the main control chip module  30 . The second switch tube  50  is connected with the first switch tube  60 . The PTC thermistor, the second switch tube  50 , the rectifier tube D 1  and the current limit resistor R 1  connect in order. The other end of the PTC thermistor connects with a positive output end of the battery pack  10 , and the other end of the current limit resistor R 1  connects with the positive electrode of the energy storage capacitor C 1 . It can be seen that the pre-charging circuit is connected in series with the energy storage capacitor C 1  and constitutes an integral circuit, so that in the pre-charging stage, the main control chip module  30  can directly send a control command to the first switch tube  60 , and then switch on the second switch tube  50 . At this time, a path composed of the PTC thermistor, the rectifier tube D 1  and the current limit resistor R 1  is turned on, and the energy storage capacitor C 1  is charged for the first time. 
     It should be noted that: the pre-charging circuit is controlled to turn on by the single pulse sent by the main control chip module  30  to charge the energy storage capacitor C 1  for the first time; and after the single pulse transmission is over, the main control chip module  30  will not send a single pulse to the pre-charging circuit until restart for the second time. It can also be understood as that: the pre-charging circuit ends the task by only sending a pulse waveform when it is turned on. 
     The charge circuit includes an electronic switch module  20  and a third switch tube  70  connected to the electronic switch module  20 . The third switch tube  70  is also connected to the main control chip module  30  for receiving control signals sent by the main control chip module  30 , so as to control the electronic switch module  20  to be switched on or off. It should be noted that: the main control chip module  30  will send a control signal to the third switch tube  70  after a certain period of time of working of the pre-charging circuit. 
     The electronic switch module  20  includes a control terminal  21  connected to the third switch tube  70  and a switch terminal  22  electrically connected to the control terminal  21 . When the third switch tube  70  is switched on, the control terminal  21  forms an energized circuit and absorbs the switch terminal  22  to be switched on, so that the battery pack  10 , the switch terminal  22  and the energy storage capacitor C 1  on the main circuit are electrically connected. Two ends of the switch terminal  22  are respectively connected to the battery pack  10  and the energy storage capacitor C 1 , so that when the main control chip module  30  turns on the switch terminal  22 , the battery pack  10  can be used to charge the energy storage capacitor C 1  directly to make the storage capacitor C 1  have enough power to supply the driving circuit module  80 . 
     The first sampling circuit  100  is arranged between the electronic switch module  20  and the battery pack  10 . The second sampling circuit  110  is arranged between the electronic switch module  20  and the driving circuit module  80 . Moreover, feedback terminals of the first sampling circuit  100  and the second sampling circuit  112  are respectively connected to the main control chip module  30 . Specifically, a sampling point of the first sampling circuit  100  is taken from the positive output circuit of the battery pack  10 , and the feedback terminal is connected to the main control chip module  30  to output the voltage sampling value of the first sampling circuit  100 ; the sampling point of the second sampling circuit  110  is taken from the positive bus circuit of the energy storage capacitor C 1 , and the feedback terminal is connected to the main control chip module  30  to output the voltage sampling value of the second sampling circuit  110 . 
     The high-voltage driver switch system also includes a DC-DC switching circuit  40 . One end of the DC-DC switching circuit  40  connects with the main control chip module  30  and the other end connects with the positive output end of the battery pack  10  and the controlling terminal  21  of the electronic switch module  20 , so that the voltage output by the battery pack  10  is converted to a voltage suitable for the main control chip module  30  and the electronic switch module  20 . 
     An embodiment of the present invention also provides a switching method for high-voltage driver switch system, which mainly includes a power-on method and a power-off method. 
     The power-on method mainly includes: 
     First step: the main control chip module  30  sends a single pulse waveform with a turn-on time of about 100 ms to the first switch tube  60 , so that the first switch tube  60  is switched on and connected to ground, and the second switch tube  50  is triggered to switch on. At this time, a pre-charge circuit composed of the PTC thermistor, the first switch tube  60 , the second switch tube  50 , the rectifier tube D 1  and the current limit resistor R 1  is turned on to charge the energy storage capacitor C 1  for the first time; 
     Second step: after a certain time interval, that is, after the main control chip module  30  determines that the voltage sampling value of the second sampling circuit  110  is the same as the voltage sampling value of the first sampling circuit  100 , the charging voltage of the energy storage capacitor C 1  is equal to the voltage of the battery pack  10 , the main control chip module  30  then sends a control signal to the third switch tube  70  to switch on the third switch tube  70 , and form an energization loop at the control terminal  21 , and the switch terminal  22  is closed. At this time, the battery pack  10 , the switch terminal  22  and the energy storage capacitor C 1  form a path, and the battery pack  10  continues to charge the energy storage capacitor C 1  so that the energy storage capacitor C 1  can provide sufficient power to the drive circuit module  80 . 
     Third step: the main control chip module  30  then send a control command to the drive circuit module  80  to drive the motor  90  to work normally. 
     As can be known from the pre-charge circuit in the first step: at the moment of power-on, since the capacitor in the energy storage capacitor C 1  has not yet accumulated charge, the electromotive force E of the battery pack  10  all falls on the current limit resistor R 1 , and its maximum charging current is IO=E/R. It can be seen from this formula that: after the current limit resistor R 1  limits the current, the instantaneous current at startup becomes smaller because of current limitation of the current limit resistor R 1 . Therefore, the current limit resistor R 1  is able to effectively avoid a high current impact, which will burn the electronic switch module  20  or the battery pack  10 , caused by charging the energy storage capacitor C 1  through the electronic switch module  20  by the battery pack  10  directly. 
     The power-off method mainly includes: 
     First step: the main control chip module  30  controls the drive circuit module  80  to turn off, so that the motor  90  stops running; 
     Second step: after completing the first step, the main control chip module  30  controls the third switch tube  70  to switch off, so that the switch terminal  22  of the electronic switch module  20  is switched on. At this time, the connection between the circuit on the internal main circuit of the high-voltage driver and the battery pack  10  can be completely cut off to avoid the risk of electrification at the terminals of the plug-in socket of the battery pack  10 . 
     In summary, the high-voltage driver switch system of the present invention can first use the pre-charge circuit to pre-charge the energy storage capacitor C 1 , and then use the charge circuit to make the battery pack  10  continue to charge the energy storage capacitor C 1 , so that the current limit resistor R 1  in the pre-charge circuit can be used to reduce the instantaneous start-up current, thereby avoiding the high current impact, which will burn the electronic switch module  20  or the battery pack  10 , caused by charging the energy storage capacitor C 1  by the battery pack  10  directly; When powered-off, it can completely cut off the connection between the circuit on the internal main circuit of the high-voltage driver and the battery pack  10  to avoid the risk of electrification of the plug-in socket terminal of the battery pack  10 . 
     Compared with the conventional technology, the present invention not only prolongs the service life of the battery pack  10  and the electronic switch module  20 , protects personal safety, but also brings a good surge control performance. While protecting the working circuit, it effectively reduces the cost of circuit design and the cost of subsequent maintenance and greatly improves the market competitiveness. 
     The above embodiment is only used to illustrate present invention and not to limits the technical solutions described in present invention. The understanding of this specification should be based on those skilled in the art, although present invention has been described in detail with reference to the above embodiment. However, those skilled in the art should understand that those skilled in the art can still modify or equivalently replace present invention, and all technical solutions and improvements that do not depart from the spirit and scope of present invention should be within the scope of the claims of the invention.