Patent Publication Number: US-2022227238-A1

Title: Control device and control method for rotating electric machine

Description:
TECHNICAL FIELD 
     The present invention relates to a control device for a rotating electric machine. 
     BACKGROUND ART 
     Background art of the present technical field includes the following prior art. PTL 1 (JP 2007-259644 A) discloses a power generation electric device for a vehicle including: a generator motor including at least two three-phase windings disposed apart from each other by a predetermined spatial phase difference; at least two orthogonal converters individually exchanging a three-phase AC current with each of the three-phase windings; and a controller that controls the orthogonal converter. In the power generation electric device for the vehicle, the controller intermittently controls a switching element of a first orthogonal converter in response to a request for torque or a rotation speed to energize the first three-phase winding with a first three-phase AC current, and a switching element of the second orthogonal converter is intermittently controlled such that a second three-phase AC current with which the second three-phase winding is energized secures a predetermined current phase difference with respect to the first three-phase AC current. 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2007-259644 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     A regenerative brake that decelerates by regenerative torque of a motor is adopted in an electric vehicle or a hybrid vehicle. In addition, a regenerative cooperative brake using both the regenerative brake and a mechanical brake requires a dedicated brake system that controls switching between the regenerative brake and the mechanical brake, and it is difficult to adopt the regenerative cooperative brake in many automobiles from the viewpoint of cost. For this reason, desirably the regenerative brake performs control from deceleration to stopping. 
     However, when the deceleration to the stopping of the vehicle is controlled only by the regenerative brake, a margin in which electric power can be received by a battery during braking is required. For this reason, there is a demand for a method of controlling driving force and braking force of the motor while a SOC of the battery is considered. 
     Solution to Problem 
     A representative example of the invention disclosed in the present application is as follows. That is, a control device controlling a rotating electric machine including windings of a plurality of independent system. The rotating electric machine is controlled in: a first mode in which an AC current is energized to the windings of the plurality of systems to generate torque such that a combined magnetic field generated in the windings is greater than or equal to a predetermined value; and a second mode in which the AC current having a phase difference different from that in the first mode is energized to the windings of the plurality of systems, the combined magnetic field generated in the windings is made smaller than the predetermined value, and current greater than or equal to that in the first mode flows. 
     Advantageous Effects of Invention 
     According to one aspect of the present invention, the driving force and the braking force of the rotating electric machine can be controlled while the SOC of the battery is considered. Objects, configurations, and advantageous effects other than those described above will be clarified by the descriptions of the following embodiment. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram illustrating a hybrid electric vehicle equipped with a rotating electric machine driving system according to an embodiment of the present invention. 
         FIG. 2  is a diagram illustrating a configuration of the rotating electric machine driving system and a rotating electric machine of the embodiment. 
         FIG. 3  is a diagram illustrating a magnetomotive force vector in a first mode during power running of the embodiment. 
         FIG. 4  is a diagram illustrating a current waveform in the first mode during the power running of the embodiment. 
         FIG. 5  is a diagram illustrating the magnetomotive force vector in a second mode during the power running of the embodiment. 
         FIG. 6  is a diagram illustrating the current waveform in the second mode during the power running of the embodiment. 
         FIG. 7  is a diagram illustrating the magnetomotive force vector in the first mode during regeneration of the embodiment. 
         FIG. 8  is a diagram illustrating the current waveform in the first mode during the regeneration of the embodiment. 
         FIG. 9  is a diagram illustrating the magnetomotive force vector in the second mode during the regeneration of the embodiment. 
         FIG. 10  is a diagram illustrating the current waveform in the second mode during the regeneration of the embodiment. 
         FIG. 11  is a diagram illustrating the magnetomotive force vector during forced discharge (third mode) of the embodiment. 
         FIG. 12  is a diagram illustrating the current waveform during the forced discharge (third mode) of the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments will be described with reference to the drawings. 
       FIG. 1  is a diagram illustrating a configuration of a vehicle (a hybrid vehicle or an electric vehicle)  10  on which a rotating electric machine control device  16  according to an embodiment of the present invention is mounted. 
     For example, the vehicle  10  that is of the hybrid vehicle is equipped with an engine  12 , a first rotating electric machine  100 , a second rotating electric machine  101 , and a high-voltage battery  201 . The battery  201  includes a secondary battery such as a lithium ion battery or a nickel hydrogen battery, and outputs high voltage DC power of 250 V to 600 V or higher. The battery  201  supplies the DC power to the rotating electric machines  100 ,  101  when the driving force by the rotating electric machines  100 ,  101  is required, and the DC power is supplied from the rotating electric machines  100 ,  101  during regenerative running. The DC power between the battery  201  and the rotating electric machines  100 ,  101  is transmitted and received through the rotating electric machine control device  16 . 
     Although not illustrated, the vehicle  10  is equipped with an auxiliary battery that supplies low voltage power (for example, 14 volt-system power). Rotating torque generated by the engine  12  and the rotating electric machines  100 ,  101  is transmitted to a front wheel  11  through a transmission  13  and a differential gear  140 . Because the rotating electric machines  100 ,  101  are configured substantially identically, the rotating electric machine  100  will be described below. 
     The rotating electric machine  100  is a built-in permanent magnet type three-phase synchronous motor. The rotating electric machine  100  operates as an electric motor that rotates a rotor by supplying a three-phase AC current to a stator coil wound around a stator core. When driven by the engine  12 , the rotating electric machine  100  operates as a generator to output generated power of the three-phase alternating current. That is, the rotating electric machine  100  has both a power running function as the electric motor that generates the rotating torque using electric energy and a regenerative function as the generator that generates the power using mechanical energy, and the above-described functions can be selectively used depending on a running state of the automobile. 
     The vehicle  10  accelerates and decelerates when a driver operates a throttle pedal and a brake pedal (not illustrated). For example, when the driver operates the throttle pedal, the driving force is generated according to a depression amount, and power running is performed. When the driver operates the brake pedal, braking force is generated according to the depression amount, and the regenerative running is performed. 
     In addition, the vehicle  10  may be accelerated and decelerated by the driver operating a single throttle pedal (not illustrated). In this case, the power running is performed to generate the driving force when the driver steps on the throttle pedal to generate the large operation amount of the throttle pedal, and the regenerative running is performed to generate the braking force when the operation amount of the throttle pedal is small. 
       FIG. 2  is a diagram illustrating a configuration of the rotating electric machine control device  16  and the rotating electric machine  100  of the embodiment. Although the control of the rotating electric machine  100  will be described below, the rotating electric machine  101  can be similarly controlled. 
     The rotating electric machine control device  16  of the embodiment 1 controls driving of the rotating electric machine  100 . For example, the rotating electric machine  100  is a motor for running of the vehicle  10 . The rotating electric machine control device  16  includes a battery  201 , a capacitor  202 , a control microcomputer  203 , a driving circuit  204 , and an inverter circuit  210 . 
     The rotating electric machine  100  is a Y-connection three-phase AC rotating electric machine of two independent systems. That is, the rotating electric machine  100  includes three-phase armature windings  102   u   1 ,  102   v   1 ,  102   w   1  respectively corresponding to a U1 phase, a V1 phase, a W1 phase of a first system, and three-phase armature windings  102   u   2 ,  102   v   2 ,  102   w   2  respectively corresponding to a U2 phase, a V2 phase, a W2 phase of a second system. Different current can flow in each phase because the armature windings  102   u  to  102   w  of each system are provided independently of each other. The armature winding  102  is connected at neutral points n 1 , n 2  for each system. The neutral points n 1 , n 2  may be provided inside the rotating electric machine  100  as illustrated in  FIG. 2 , or provided outside the rotating electric machine  100 . 
     The inverter circuit  210  drives the rotating electric machine  100  by independently controlling currents flowing through the armature windings  102   u  to  102   w . A position detector  110  that detects a magnetic pole position of the rotating electric machine  100  is attached to an output shaft of the rotating electric machine  100 . A detection result of the magnetic pole position by the position detector  110  is output to the control microcomputer  203 . 
     The battery  201  supplies the DC power to the inverter circuit  210  through DC buses  201   a ,  201   b . For example, a secondary battery such as a lithium ion battery can be used as the battery  201 . 
     The capacitor  202  absorbs a fluctuation in the DC voltage caused by the operation of the inverter circuit  210 , and is connected in parallel with the inverter circuit  210  between the DC bus  201   a  and the DC bus  201   b.    
     The control microcomputer  203  performs a predetermined current control arithmetic operation, and outputs a control signal instructing the output voltage and the output current of each phase to the driving circuit  204  based on an arithmetic result. The driving circuit  204  outputs drive signals Gu 1 , Gv 1 , Gw 1  to bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1  of the respective phases of the inverter circuit  210 , respectively. By operating the bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1  according to the drive signals Gu 1 , Gv 1 , Gw 1 , the control microcomputer  203  controls the inverter circuit  210  through the driving circuit  204 . 
     The inverter circuit  210  includes bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1  corresponding to a U phase, a V phase, a W phase of the first system, respectively. Each of the bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1  includes an IGBT that functions as a switching element of each of the upper and lower arms, and a diode provided in parallel with each IGBT. In the bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1 , each IGBT performs a switching operation according to the drive signals Gu 1 , Gv 1 , Gw 1  from the driving circuit  204 . Thus, the DC power supplied from the battery  201  is converted into three-phase AC power, and the AC current is output from the bridge circuits  211   u   1 ,  211   v   1 ,  211   w   1  to the armature windings  102   u   1 ,  102   v   1 ,  102   w   1  of each phase of the rotating electric machine  100  through an AC output lines  120  of each phase. 
     The AC output line  120  of each phase is provided with a current sensor  130  detecting each current flowing through the armature windings  102   u   1 ,  102   v   1 ,  102   w   1  of the rotating electric machine  100 . In the illustrated example, the current sensor  130  is provided inside the inverter circuit  210 . However, the current sensor  130  may be provided outside the inverter circuit  210 . The current value of each phase detected by the current sensor  130  is output to the control microcomputer  203 . The control microcomputer  203  performs predetermined current control arithmetic operation based on the operation of the throttle pedal and the brake pedal by the driver, a control command input from another ECU, the current value of each phase input from the current sensor  130 , and the detection of the magnetic pole position by the position detector  110 , and outputs a control signal instructing the driving circuit  204  to output the drive signals Gu 1 , Gv 1 , and Gw 1  of each phase based on the arithmetic result. 
     Although the operations of the control microcomputer  203 , the driving circuit  204 , and the inverter circuit  210  have been described above for the first system, the second system operates similarly. As described above, by controlling the amplitude and phase of the AC current of each phase, the magnitude and direction of the magnetomotive force of the armature winding  102  of each system are controlled, the direction and magnitude of a combined magnetomotive force are controlled, the magnitude of the current, the magnitude of the power running torque, and the magnitude of the regenerative torque are adjusted, and the amount of energy input to and output from the battery  201  is adjusted. 
       FIG. 3  is a diagram illustrating a magnetomotive force vector in a first mode during the power running, and  FIG. 4  is a diagram illustrating a current waveform in the first mode during the power running. 
     In the first mode during the power running, in-phase currents are caused to flow through the armature windings  102  of the respective systems, and the control is performed such that the direction of the magnetomotive force by the armature windings  102  of the first system and the direction of the magnetomotive force by the armature windings  102  of the second system approach each other. That is, as illustrated in  FIG. 3 , the direction of the magnetomotive force of each system deviates from the difference (30° in  FIG. 3 ) in a winding position of the armature winding  102  of each system, but the combined magnetomotive force is in the direction close to the direction of the magnetomotive force of each system, the combined magnetomotive force increases, and the generated torque increases. That is, in the first mode, a current amplitude Ia and a current phase β (current phase β=0) are adjusted such that the current value decreases with respect to the target torque. 
     Although the directions of the magnetomotive forces of the systems are shifted by 30° in the case of  FIG. 3 , the directions of the magnetomotive forces of the respective systems can be equalized to each other by causing the current advanced by 30° from the armature winding  102  of the first system to flow through the armature winding  102  of the second system. In this way, the combined magnetomotive force can be increased greater than that in the first mode during the power running in  FIG. 3 . 
       FIG. 5  is a diagram illustrating the magnetomotive force vector in a second mode during the power running, and  FIG. 6  is a diagram illustrating the current waveform in the second mode during the power running. 
     In the second mode during the power running, the currents of different phases (for example, 60° as illustrated in  FIG. 6 ) are caused to flow through the armature windings  102  of each systems, and the control is performed such that the direction of the magnetomotive force by the armature windings  102  of the first system and the direction of the magnetomotive force by the armature windings  102  of the second system are orthogonal to each other. Specifically, as illustrated in  FIG. 5 , the direction of the magnetomotive force of each system is shifted by 90° of a sum of the phase difference 60° of the current of each system and the difference (30° in  FIG. 5 ) of the winding position of the armature winding  102  of each system, and the combined magnetomotive force becomes small. That is, in the second mode, the current amplitude Ia and the current phase β (current phase β=0) are adjusted such that the current value increases with respect to the target torque. 
     As described above, the control microcomputer  203  selects the first mode, the second mode, or another operation mode during the power running according to the operation amount of the throttle pedal by the driver, and controls the amplitude and the phase of the current flowing through the armature winding  102  of the rotating electric machine  100 . For example, in the first mode during the power running, the current value can be reduced in order to obtain the same torque, and the vehicle can be controlled with high energy consumption efficiency. On the other hand, in the second mode during the power running, the current value can be increased in order to obtain the same torque, the energy consumption can be increased as compared with the first mode, and the SOC of the battery  201  can be controlled so as not to be high. For example, in what is called look-ahead control in which the running is controlled in consideration of a situation of a future running route, desirably charging and discharging of the battery  201  is controlled depending on a gradient of a previous road and a traffic situation. Specifically, when the battery  201  is actively consumed in the second mode before entering a downhill, the required braking force by the regeneration is obtained on the downhill. 
       FIG. 7  is a diagram illustrating the magnetomotive force vector in the first mode during regeneration, and  FIG. 8  is a diagram illustrating the current waveform in the first mode during the regeneration. The control microcomputer  203  selects the first mode during the regeneration at the time of deceleration according to the operation amount of the throttle pedal or the brake pedal by the driver, and controls the amplitude and the phase of the current flowing to the armature winding  102  of the rotating electric machine  100 . 
     In the first mode during the regeneration, the in-phase currents are caused to flow through the armature windings  102  of the respective systems, and the control is performed such that the direction of the magnetomotive force by the armature windings  102  of the first system and the direction of the magnetomotive force by the armature windings  102  of the second system approach each other. That is, as illustrated in  FIG. 7 , the direction of the magnetomotive force of each system deviates from the difference (30° in  FIG. 7 ) in the winding position of the armature winding  102  of each system, but the combined magnetomotive force is in the direction close to the direction of the magnetomotive force of each system, the magnitude of the combined magnetomotive force increases, and the generated torque increases. In the first mode, because the current amplitude Ia and the current phase β (current phase β=180) are adjusted such that the current value is minimized with respect to the target torque, the efficiency of the generator is lowered, and the current for obtaining the desired torque (braking force) is reduced. 
       FIG. 9  is a diagram illustrating the magnetomotive force vector in the second mode during regeneration, and FIG. is a diagram illustrating the current waveform in the second mode during the regeneration. The control microcomputer  203  selects the second mode during the regeneration at the time of deceleration according to the operation amount of the throttle pedal or the brake pedal by the driver, and controls the amplitude and the phase of the current flowing to the armature winding  102  of the rotating electric machine  100 . 
     In the second mode during the regeneration, the currents of different phases (for example, 300° as illustrated in  FIG. 10 ) are caused to flow through the armature windings  102  of each systems, and the control is performed such that the direction of the magnetomotive force by the armature windings  102  of the first system and the direction of the magnetomotive force by the armature windings  102  of the second system are orthogonal to each other. Specifically, as illustrated in  FIG. 9 , the direction of the magnetomotive force of each system is shifted by 90° of a sum of the phase difference 60° of the current of each system and the difference (30° in  FIG. 9 ) of the winding position of the armature winding  102  of each system, and the combined magnetomotive force becomes small. In the second mode, because the current amplitude Ia and the current phase β (current phase β=180) are adjusted such that the current value increases with respect to the target torque, the efficiency of the generator increases, and the current for obtaining the desired torque (braking force) increases. 
     As described above, the control microcomputer  203  selects the first mode, the second mode, or another operation mode during the power running according to the operation amount of the throttle pedal by the driver, and controls the amplitude and the phase of the current flowing through the armature winding  102  of the rotating electric machine  100 . For example, in the first mode during the regeneration, the current value can be reduced in order to obtain the braking torque, the amount of energy charged in the battery  201  can be reduced as compared with the second mode, and the control can be performed such that the SOC of the battery  201  does not become high. 
     On the other hand, in the second mode during the regeneration, the current value can be increased in order to obtain the braking torque, the amount of energy charged in the battery  201  increases, and the energy efficiency can be improved. For this reason, in the state in which the SOC of the battery  201  is high, the first mode may be selected to reduce the electric power charged in the battery  201  while the required braking force is obtained, and in the state where the SOC of the battery  201  is low, the second mode may be selected to increase the electric power charged in the battery  201 . 
     In particular, in the automobile in which one-pedal control for controlling from the acceleration to the deceleration with the single throttle pedal described above, a margin in which the battery  201  can receive the electric power is required because the deceleration control is performed by the regenerative brake when the operation amount of the throttle pedal is small. For this reason, during the one-pedal control, when the first mode and the second mode are switched according to the SOC of the battery  201 , the SOC of the battery  201  can be controlled so as not to be high, and the vehicle can be smoothly controlled. 
       FIG. 11  is a diagram illustrating the magnetomotive force vector in a discharge mode (third mode), and  FIG. 12  is a diagram illustrating the current waveform in the discharge mode (third mode). 
     The third mode is a mode for discharging charges of the battery  201  and the capacitor  202 . For example, the third mode is used when the vehicle consumes the energy of the battery  201  during coast running (torque=0) or when the vehicle rapidly discharges the charge of the capacitor  202  during stopping. 
     In the third mode, the currents of different phases (for example, 150° as illustrated in  FIG. 12 ) are caused to flow through the armature winding  102  of each system, and the control is performed such that the direction of the magnetomotive force by the armature winding  102  of the first system and the direction of the magnetomotive force by the armature winding  102  of the second system are opposite to each other. Specifically, as illustrated in  FIG. 11 , the direction of the magnetomotive force of each system is shifted by 180° of the sum of the phase difference of 150° of the current of each system and the difference (30° in  FIG. 11 ) of the winding position of the armature winding  102  of each system, the combined magnetomotive force becomes zero, and the torque is not generated. 
     In the conventional discharge mode, the rotor is stopped and the CD current flows to the armature winding  102  of a specific system, so that there is a problem in that the specific armature winding  102  generates heat according to the DC resistance of the armature winding  102 . In addition, the magnet generates heat because a magnetic field due to the current flowing through the armature winding  102  is generated immediately above the magnet. However, in the third mode of the embodiment, because the AC current flows through the armature windings  102  of the two systems, a calorific value (temperature rise) of the armature windings  102  can be averaged. In addition, the magnet does not generate the heat because the magnetic fields are canceled by the windings of the two systems. 
     In addition, in what is called the look-ahead control in which the running is controlled in consideration of the situation of the future running route, desirably the charging and discharging of the battery  201  depending on the gradient of the previous road and the traffic situation. For example, when the battery  201  is actively discharged in the third mode during the coast running before entering the downhill, the required braking force by the regenerative brake is obtained on the downhill. In addition, when the EV running is desired at a congestion spot of the running route ahead, before the congestion spot, the power consumption may be suppressed by the first mode during the power running, or the charge amount may be increased by the second mode during the regeneration to secure the electric power for the EV running. 
     In addition, when an occupant is required to be rescued because the vehicle is in an emergency stop due to an accident or a failure, the battery  201  is required to be shut off and the electric power of the capacitor  202  is required to be quickly discharged. At this point, electric shock of a rescuer can be prevented by consuming the electric power of the capacitor  202  in the third mode. 
     As described above, according to the embodiment of the present invention, in the control device (the control microcomputer  203  of the rotating electric machine control device  16 ) that controls the rotating electric machine  100  including the windings of the plurality of independent systems, the rotating electric machine  100  is controlled by the first mode in which the AC current is passed through the windings of the plurality of systems to generate the torque such that the combined magnetic field generated in the windings is greater than or equal to the predetermined value and the second mode in which the alternating current having the phase difference different from the first mode is passed through the windings of the plurality of systems to cause the combined magnetic field generated in the windings to be smaller than the predetermined value, and the current greater than or equal to that of the first mode is passed in the second mode. Consequently, the driving force and the braking force of the rotating electric machine can be controlled in consideration of the SOC of the battery. That is, the electric power of the battery  201  can be actively consumed while the required driving torque is generated by the second mode during the power running, and the electric power charged in the battery  201  can be reduced while the required braking torque is generated by the first mode during the regeneration. For this reason, the temperature rise of the armature winding  102  can be suppressed. In addition, as compared with the conventional control in which the power consumption of the battery  201  is adjusted by the magnitude of a d-axis current, because the power consumption is adjusted by flowing the AC current through the windings of the two systems, the temperature rise of the armature winding  102  can be equalized, and the temperature rise of the magnet can be suppressed. 
     In addition, the control device controls the motor in the third mode in which the electric power of at least one of the battery  201  and the capacitor  202  is consumed by the AC current flowing through the winding while the combined magnetic field generated is set to zero by energizing the AC currents having different phases to the windings of the plurality of systems. The magnetic field generated by the three-phase AC current flowing through the armature winding  102  of the first system and the magnetic field generated by the three-phase AC current flowing through the armature winding  102  of the second winding are canceled, and the armature winding  102  is energized without generating the torque. Consequently, the capacitor  202  provided at the preceding stage of the inverter circuit  210  that supplies the AC power to the rotating electric machine  100  can be efficiently and quickly discharged, and the charge amount of the battery  201  can be reduced during the coast running. 
     In addition, the control device switches between the power running control and the regenerative control by the operation amount of one pedal, and switches between the first mode and the second mode according to the charge amount of the battery  201  during the regenerative control. Consequently, the charge amount of the battery  201  can be adjusted while the acceleration or the deceleration is generated according to the situation of the vehicle, the control can be performed such that the SOC of the battery  201  does not become high, and the vehicle can be smoothly controlled. 
     The present invention is not limited to the above-described embodiment, but includes various modifications and equivalent configurations within the spirit of the appended claims. For example, the above embodiment has been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to the embodiment having all the configurations described above. A part of the configuration of one embodiment may be replaced with the configuration of another embodiment. The configuration of another embodiment may be added to the configuration of a certain embodiment. In a part of the configuration of each embodiment, another configuration may be added, deleted, or replaced. 
     In addition, a part or all of the above-described configurations, functions, processing units, processing means, and the like may be implemented by hardware by, for example, designing with an integrated circuit, or may be implemented by software by a processor interpreting and executing a program for implementing each function. 
     Information such as a program, a table, and a file implementing each function can be stored in a storage device such as a memory, a hard disk, and a solid state drive (SSD), or a recording medium such as an IC card, an SD card, and a DVD. 
     The control line and the information line indicate those which are considered necessary for the description, but do not necessarily indicate all the control lines and information lines necessary for the mounting. Actually, it can be considered that almost all the components are connected to each other. 
     REFERENCE SIGNS LIST 
     
         
           10  vehicle 
           11  front wheel 
           12  engine 
           13  transmission 
           16  rotating electric machine control device 
           100 ,  101  rotating electric machine 
           102  armature winding 
           110  position detector 
           120  AC output line 
           130  current sensor 
           140  differential gear 
           201  battery 
           201   a ,  201   b  DC bus 
           202  capacitor 
           203  control microcomputer 
           204  driving circuit 
           210  inverter circuit 
           211  bridge circuit