JP6036649B2 - Vehicle control device - Google Patents

Description

The present invention relates to a technical field of a vehicle control device that controls a vehicle including an electric motor.

  In this type of technical field, there is a control device for a hybrid vehicle that reduces the engine speed of an internal combustion engine using a braking force due to a two-phase short circuit or a three-phase short circuit of a three-phase AC motor generator during vehicle braking (Patent Literature). 1).

JP 2006-288051 A

  Various phase short-circuit controls including the above-described two-phase short circuit, three-phase short circuit, or one-phase short circuit that short-circuits only one phase include as one of the purposes to reduce the power loss associated with the switching operation of the switching element. This control is fundamentally different from known power control (hereinafter referred to as “normal control” where appropriate) according to the torque command value, which is normally performed when the vehicle travels, such as PWM (Pulse Width Modulation) control. Control. Therefore, a corresponding switching time is required until the electric power control method of the electric motor is switched from the phase short-circuit control to the normal control and the torque corresponding to the torque command value is output from the electric motor.

  On the other hand, as a vehicle including an internal combustion engine and an electric motor, a vehicle including a plurality of electric motors is known. Even in such a vehicle, the phase short-circuit control can be applied to each of the plurality of electric motors.

  However, in this case, the timing at which the return from the phase short-circuit control to the normal control is completed does not always match between the motors due to the influence of the switching time and the transmission delay of the control signal. Therefore, if the torque command value determined for each electric motor in consideration of the torque balance of the entire vehicle is output to a plurality of electric motors at the same time, in a transitional period when switching from phase short-circuit control to normal control, The torque balance of the entire vehicle deviates from the target, and comfort is easily impaired. Conventionally, there is no technology that can solve such problems.

  This invention is made in view of the problem which concerns, and provides the vehicle control apparatus which can suppress the fall of the comfort at the time of the return from phase short circuit control in the vehicle provided with two or more electric motors. To do.

  In order to solve the above-described problems, a vehicle control device according to the present invention includes a plurality of three-phase AC motors including a first motor that rotates synchronously with a drive shaft of a vehicle, and a three-phase in each of the plurality of three-phase AC motors. A power converter comprising a first switching element and a second switching element electrically connected in series corresponding to each of the plurality of three-phase AC motors, and converting power supplied to each of the plurality of three-phase AC motors from DC to AC A vehicle control apparatus for controlling a vehicle comprising: the power conversion based on a torque command value corresponding to each of the plurality of three-phase AC motors set based on driving conditions of the vehicle in normal control The vehicle is stopped when the first control means for controlling the motor and the rotation speed of the first electric motor are equal to or lower than a first threshold value and a stop operation is performed to stop the vehicle. When the determination means determines that the vehicle is stopped, all of one of the first switching element and the second switching element are turned off, and the first A second control means for controlling the power converter so that at least one of the switching element and the second switching element is turned on; and a predetermined return of the power converter in the predetermined state And a third control means for outputting the torque command value after a predetermined time has elapsed from the output of the return command signal when returning to the normal control in response to the command signal. .

  According to the vehicle control device of the present invention, when the normal control is performed by the first control unit, each of the plurality of electric motors is drive-controlled according to the torque command value output by the third control unit. This normal control is, for example, control during vehicle travel, and includes known power control such as PWM control.

  On the other hand, at the time of executing this normal control, it is determined by the determining means whether or not the vehicle is stopped. When it is determined by the determination means that the vehicle is stopped, the power converter is brought into a predetermined state by the second control means.

  Here, the predetermined state refers to a state in which all of one of the first switching element and the second switching element are in an off state and at least one of the other elements is in an on state. Hereinafter, the control performed by the second control means to bring the power converter into the predetermined state is appropriately expressed as “phase short-circuit control”.

  The phase short-circuit control includes one-phase short-circuit control in which one of the other elements is short-circuited, two-phase short-circuit control in which two are short-circuited, and three-phase short-circuit control in which three are short-circuited. In the phase short-circuit control, since the switching operation in the first or second switching element is stopped, power consumption can be reduced.

  According to the vehicle control device of the present invention, the control mode of the electric motor returns from the phase short-circuit control to the normal control in response to a return command signal that is output when a predetermined return condition is satisfied. At this time, the third control means outputs the torque command value after a predetermined time has elapsed from the time when the return command signal is output. This predetermined time is preferably longer than the switching time that is different for each motor, which is required for switching from phase short-circuit control to normal control. Moreover, this predetermined time is preferably a time equivalent to the longest time among the switching times different for each electric motor. Such a predetermined time can be determined in advance experimentally, empirically or theoretically.

  As described above, according to the vehicle control device of the present invention, the output of the torque command value is on standby until a predetermined time elapses from the output time point of the return command signal. Therefore, it is possible to prevent a situation in which the torque command value is supplied before the motor is ready to be driven by normal control, and to suppress a decrease in comfort due to the deviation of the torque balance of the plurality of motors from the original target. can do.

  In the vehicle control device according to the present invention, it is only necessary that the torque command value is output after a predetermined time has elapsed from the output of the return command signal, and for determining the output start timing of the torque command value. It is not always necessary to obtain a trigger from the output of the return command signal. That is, another signal that corresponds one-to-one with the output of the return command signal may be used as a control base point.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

1 is a schematic configuration diagram conceptually showing a configuration of a vehicle drive system according to an embodiment of the present invention. It is a schematic circuit diagram of PCU in the vehicle of FIG. It is a schematic block diagram of the control apparatus which controls the vehicle of FIG. It is a block diagram of HVECU in the control apparatus of FIG. It is a block diagram of MG2ECU in the control apparatus of FIG. It is a flowchart of a vehicle stop determination process. It is a flowchart of a phase short circuit process. It is a figure which illustrates the torque transition of MG1 and MG2 in the return transition period from phase short-circuit control to normal control in the comparative example which should be used for comparative examination with this invention. It is a figure which illustrates the torque transition of MG1 and MG2 in the return transition period from phase short circuit control to normal control when the phase short circuit control which concerns on this invention is performed.

<Embodiment of the Invention>
Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of Embodiment>
First, a vehicle 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the drive system of the vehicle 1.

  In FIG. 1, a hybrid vehicle 1 is an example of a “vehicle” according to the present invention that includes a PCU (Power Control Unit) 10, an engine EG, a motor generator MG1, a motor generator MG2, a power split mechanism PG, and a speed reduction mechanism RG. It is a hybrid vehicle.

  The PCU 10 is a power control device for controlling the driving state of the motor generators MG1 and MG2. The configuration of the PCU 10 will be described in detail with reference to FIG.

  The engine EG is, for example, a multi-cylinder gasoline engine, and is an internal combustion engine that functions as one power source of the hybrid vehicle 1. Here, although the engine EG is a multi-cylinder gasoline engine, the engine EG may have any configuration in terms of the number of cylinders, the cylinder arrangement, the fuel type, and the like.

  Motor generator MG1 is a three-phase AC motor generator that is an example of a “three-phase AC motor” according to the present invention, and includes a power running function that converts electrical energy into kinetic energy, and a regeneration function that converts kinetic energy into electrical energy. Is provided.

  The motor generator MG2 is another example of the “three-phase AC motor” according to the present invention, and a three-phase AC motor generator that is an example of the “first motor” according to the present invention. Similarly to the motor generator MG1, A power running function that converts electrical energy into kinetic energy and a regenerative function that converts kinetic energy into electrical energy are provided.

  The power split mechanism PG is disposed between the sun gear S1 provided at the center, the ring gear R1 provided concentrically on the outer periphery of the sun gear S1, and the outer periphery of the sun gear S1. This is a planetary gear mechanism with two degrees of rotation including a plurality of pinion gears P1 that revolve while rotating and a carrier C1 that supports the rotation shaft of each pinion gear.

  In power split device PG, sun gear S1 is connected to the output rotation shaft of motor generator MG1, and the rotation speed is equivalent to MG1 rotation speed Nmg1, which is the rotation speed of motor generator MG1. The ring gear R1 is fixed to the output shaft OS of the power split mechanism PG, and the rotation speed is equivalent to the output rotation speed Nout that is the rotation speed of the output shaft OS. Further, the carrier C1 is connected to the input shaft IS of the power split mechanism PG connected to the engine output shaft of the engine EG, and the rotational speed thereof is equivalent to the engine rotational speed Ne of the engine EG.

  Note that the output rotation shaft of motor generator MG2 is connected to output shaft OS, and output rotation speed Nout described above is equal to MG2 rotation speed Nmg2 which is the rotation speed of motor generator MG2.

  A first resolver rv1 for detecting the rotation angle of motor generator MG1 is attached to the output rotation shaft of motor generator MG1. The rotation angle of motor generator MG1 detected by first resolver rv1 is used for calculation of MG1 rotation speed Nmg1. Similarly, a second resolver rv2 for detecting the rotation angle of motor generator MG2 is attached to the output rotation shaft of motor generator MG2. The rotation angle of motor generator MG2 detected by second resolver rv2 is used for calculation of MG2 rotation speed Nmg2.

  The output shaft OS of the power split mechanism PG is coupled to the drive wheels DW of the hybrid vehicle 1 via a speed reduction mechanism RG including various speed reduction gears, a differential, and the like. Therefore, the output shaft rotation speed Nout and the MG2 rotation speed Nmg2 are uniquely related to the vehicle speed V, which is the speed of the hybrid vehicle 1, respectively. Further, the motor torque Tmg2 supplied to the output shaft OS when the motor generator MG2 is powered is used as the driving torque of the hybrid vehicle 1. Conversely, the driving torque input to the output shaft OS during regeneration of the motor generator MG2 is used for power generation.

  Next, the configuration of the PCU 10 will be described with reference to FIG. FIG. 2 is a schematic circuit diagram of the PCU 10. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  In FIG. 2, a PCU 10 is a power control device that controls input / output of power between the DC power supply B and each motor generator, and includes a boost converter 200, an MG2 inverter 300, and an MG1 inverter 400.

  The DC power supply B is a power supply voltage VB (for example, 200V) in which a plurality of (for example, several hundreds) secondary battery cells (for example, a cell voltage number V) such as nickel metal hydride batteries and lithium ion batteries are connected in series. ) Secondary battery unit. As the DC power source B, an electric double layer capacitor, a large-capacity capacitor, a flywheel, or the like may be used instead of or in addition to this type of secondary battery.

  Boost converter 200 is a boost circuit including a reactor L1, switching elements Q1 and Q2, diodes D1 and D2, and a capacitor C.

  In step-up converter 200, one end of reactor L1 is connected to a positive line (not shown) connected to the positive electrode of DC power supply B, and the other end is an intermediate point between switching element Q1 and switching element Q2, that is, switching. It is connected to a connection point between the emitter terminal of element Q1 and the collector terminal of switching element Q2.

  The switching elements Q1 and Q2 are electrical switching elements connected in series between the positive electrode line and a negative electrode line (not shown) connected to the negative electrode of the DC power source B. The collector terminal of the switching element Q1 is connected to the positive electrode line, and the emitter terminal of the switching element Q2 is connected to the negative electrode line. The diodes D1 and D2 are rectifying elements that allow only current from the emitter side to the collector side in each switching element.

  In this embodiment, these switching elements are composed of a switching element Q1 on the higher potential side than the connection point with the end of the reactor L1, and a switching element Q2 on the lower potential side. The boost converter is configured. However, such a configuration of the switching element is an example, and the boost converter may be a one-arm type boost converter corresponding to the one provided with only the switching element Q2 in FIG.

  The switching elements Q1 and Q2 and each switching element (Q3 to Q8 and Q13 to Q18) of each inverter described later are configured as, for example, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or the like.

  The capacitor C is a capacitor connected between the positive electrode line and the negative electrode line. The voltage across terminals of the capacitor C, that is, the potential difference VH between the positive line and the negative line is the output voltage of the boost converter 200.

  The MG2 inverter 300 includes a U-phase arm 300U including a p-side switching element Q3 and an n-side switching element Q4, a V-phase arm 300V including a p-side switching element Q5 and an n-side switching element Q6, and a p-side switching element Q7 and an n-side. It is an example of a “power converter” according to the present invention including a W-phase arm 300W including a switching element Q8. Each arm of the MG2 inverter 300 is connected in parallel between the positive line and the negative line. The p-side switching element in each arm is an example of the “first switching element” according to the present invention, and the n-side switching element is also an example of the “second switching element” according to the present invention.

  The switching elements Q3 to Q8 are connected to rectifying diodes D3 to D8 that allow current to flow from the emitter side to the collector side, similarly to the switching elements Q1 and Q2 in the boost converter 200 described above. Further, the intermediate point between the p-side switching element and the n-side switching element of each phase arm in MG2 inverter 300 is connected to each phase coil of motor generator MG2.

  The MG1 inverter 400 includes a U-phase arm 400U including a p-side switching element Q13 and an n-side switching element Q14, a V-phase arm 400V including a p-side switching element Q15 and an n-side switching element Q16, and a p-side switching element Q17 and an n-side. It is an example of the “power converter” according to the present invention including a W-phase arm 400W including the switching element Q18. Each arm of the MG1 inverter 400 is connected in parallel between the positive line and the negative line. The p-side switching element in each arm is an example of the “first switching element” according to the present invention, and the n-side switching element is also an example of the “second switching element” according to the present invention.

  Note that rectifying diodes D13 to D18 that flow current from the emitter side to the collector side are connected to the switching elements Q13 to Q18, respectively, as with the switching elements Q1 and Q2 in the boost converter 200 described above. Further, the intermediate point between the p-side switching element and the n-side switching element of each phase arm in MG1 inverter 400 is connected to each phase coil of motor generator MG1.

  In the hybrid vehicle 1, the PCU 10 is controlled by the control device 100. Here, the configuration of the control device 100 will be described with reference to FIG. FIG. 3 is a block diagram of the control device 100.

  In FIG. 3, the control device 100 is a computer device configured to be able to control the operation of the hybrid vehicle 1. Control device 100 includes a plurality of ECUs (Electronic Controlled Units) including HVECU 110, MG2ECU 120, and MG1ECU 130. Each of these ECUs constituting the control device 100 is electrically connected via the control bus 11.

  Note that the control device 100 appropriately includes a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory) for storing information necessary for its operation. In this ROM, for example, control programs relating to various controls executed by the respective ECUs are stored. In addition, in the RAM, for example, various information that should be temporarily stored in the execution process of the various controls is stored.

  The HVECU 110 is an ECU that comprehensively controls the operation of the PCU 10. Here, the configuration of the HVECU 110 will be described with reference to FIG. FIG. 4 is a block diagram of the HVECU 110.

  4, the HVECU 110 includes an inverter input calculation unit 111, an addition / subtraction unit 112, a voltage control calculation unit 113, a carrier generation unit 114, and a comparator 115.

  Inverter input calculation unit 111 is a circuit that generates a VH command value VHtg that is a target value of output voltage VH of boost converter 200. The inverter input calculation unit 111, for example, includes a motor rotational speed MRN (that is, MG1 rotational speed Nmg1 and MG2 rotational speed Nmg2) and a motor generator torque command value TR (that is, MG1 torque command value TR1 and MG2 torque command value TR2). The VH command value VHtg is generated based on the output value of each motor generator calculated from the above so that the loss when driving each motor generator is minimized. Such a value of the VH command value VHtg is adapted beforehand experimentally, empirically or theoretically, and stored in the ROM as a conforming value. The torque command value TR (ie, TR1 and TR2) of the motor generator is determined by various known methods based on the driving conditions of the hybrid vehicle 1 and the like.

  Addition / subtraction unit 112 is a calculator that subtracts the detected value of output voltage VH of boost converter 200 from VH command value VHtg and outputs the subtraction result to voltage control calculation unit 113.

  When voltage control calculation unit 113 receives a subtraction result obtained by subtracting the detection value of output voltage VH from VH command value VHtg from addition / subtraction unit 112, output voltage VH of boost converter 200 is made to match VH command value VHtg. Calculate the control amount. At this time, for example, a known PI control calculation including a proportional term (P term) and an integral term (I term) is used. The voltage control calculation unit 113 outputs the calculated control amount to the comparator 115 as a voltage command value.

  On the other hand, the carrier generation unit 114 generates a carrier signal composed of a triangular wave and sends it to the comparator 115. The comparator 115 compares the voltage command value supplied from the voltage control calculation unit 113 with this carrier signal, and generates a signal PWC whose logic state changes according to the magnitude relationship between the voltage values. This generated signal PWC is output to switching elements Q1 and Q2 of boost converter 200.

  Supplementally, boost converter 200 is controlled by boost control executed by HVECU 110. In the step-up control, the voltage between the positive line and the negative line, that is, the output voltage VH can be boosted to the power supply voltage VB or higher of the DC power supply B based on the signal PWC. At this time, if the output voltage VH is lower than the target VH command value VHtg, the on-duty of the switching element Q2 is relatively increased, and the current flowing from the DC power source B side to the MG2 inverter 300 side through the positive line is increased. The output voltage VH can be increased. On the other hand, if the output voltage VH is higher than the VH command value VHtg, the on-duty of the switching element Q1 is relatively increased, and the current flowing through the positive line from the inverter 300 side to the DC power source B side can be increased. The voltage VH can be reduced.

  The HVECU 110 is configured as described above. The configuration illustrated in FIG. 4 is a circuit configuration that realizes voltage control, but the control mode of the boost converter 200 is not limited to such voltage control, and may be current control, for example.

  Returning to FIG. 3, MG2ECU 120 is an ECU that controls the driving state of motor generator MG2 via MG2 inverter 300. Here, the configuration of MG2ECU 120 will be described with reference to FIG. FIG. 5 is a block diagram of the MG2ECU 120.

  In FIG. 5, the MG 2 ECU 120 includes a current command conversion unit 121, a current control unit 122, a two-phase / three-phase conversion unit 123, a three-phase / two-phase conversion unit 124, a PWM conversion unit 125, and a carrier generation unit 126.

  Current command conversion unit 121 generates two-phase current command values (Idtg, Iqtg) based on torque command value TR2 of motor generator MG2.

  On the other hand, from the MG2 inverter 300, the v-phase current Iv and the w-phase current Iw are supplied to the three-phase / two-phase converter 124 as feedback information. In the three-phase / 2-phase converter 124, the three-phase current value is converted from the v-phase current Iv and the w-phase current Iw into a two-phase current value composed of the d-axis current Id and the q-axis current Iq. The converted two-phase current value is sent to the current control unit 122.

  In the current control unit 122, based on the difference between the two-phase current command value generated in the current command conversion unit 121 and the two-phase current values Id and Iq received from the three-phase / two-phase conversion unit 124, d A two-phase voltage command value composed of the shaft voltage Vd and the q-axis voltage is generated. The generated two-phase voltage command values Vd and Vqh are sent to the two-phase / three-phase converter 123.

  In the two-phase / three-phase converter 123, the two-phase voltage command values Vd and Vq are converted into the three-phase voltage command values Vu, Vv, and Vw. The converted three-phase voltage command values Vu, Vv, and Vw are sent to the PWM conversion unit 125.

  The PWM converter 125 receives a carrier Car having a predetermined carrier frequency fcar generated by the carrier generator 126 from the carrier generator 126, and the carrier Car and the converted three-phase voltage command values Vu and Vv. And the magnitude relationship with Vw. Further, the PWM converter 125 generates U-phase switching signals Gup and Gun, V-phase switching signals Gvp and Gvn, and W-phase switching signals Gwp and Gwn whose logic states change according to the comparison result, and an inverter for MG2 300.

  More specifically, among the switching signals corresponding to each phase (300U, 300V, and 300W), the signal with the identifier “p” added is the p-side switching element (Q3, Q5) among the switching elements of each phase. And Q7), a signal with an identifier “n” added is a drive signal for driving the n-side switching elements (Q4, Q6 and Q8) among the switching elements of each phase. Means.

  Here, in particular, in the comparison between the carrier Car and each phase voltage command value, when each phase voltage command value matches the carrier Car from a value smaller than the carrier Car, a switching signal for turning on the p-side switching element is generated. The Further, when each phase voltage command value matches the carrier Car from a value larger than the carrier Car, a switching signal for turning on the n-side switching element is generated. That is, the switching signal is a signal that is turned on and off, and one of the p-side and n-side switching elements is always on and the other is off.

  When MG2 inverter 300 changes or is maintained in the driving state of each switching element defined by each phase switching signal, motor generator MG2 is driven according to the circuit state corresponding to the changed or maintained driving state. Is done. Note that such a control mode of the MG2 inverter 300 is a so-called PWM control mode and an example of “normal control” according to the present invention.

  In general, a well-known overmodulation control and rectangular wave control are often used in combination with the above-described PWM control in a motor generator for driving a vehicle. Also in the hybrid vehicle 1 according to the present embodiment, the control mode of the MG2 inverter 300 may be appropriately switched according to the traveling condition of the vehicle.

  In the present embodiment, the MG2ECU 120 that drives the motor generator MG2 via the MG2 inverter 300 has been described, but the MG1ECU 130 that drives the motor generator MG1 via the MG1 inverter 400 is also basically shown in FIG. The MG2ECU 120 has the same configuration except for the reference number.

  Returning to FIG. 3, sensor outputs are input to the control device 100 from various sensors provided in the hybrid vehicle 1 via the control bus 11. For example, the accelerator opening degree Ta is input from the accelerator sensor 12, the brake pedal operation amount Tb is input from the brake sensor 13, and the vehicle speed V is input from the vehicle speed sensor 14. Further, the rotation angles of the motor generators MG1 and MG2 are input from the first resolver rv1 and the second resolver rv2 described above. These are converted into MG1 rotational speed Nmg1 and MG2 rotational speed Nmg2, respectively, by arithmetic processing inside HVECU 110.

  Although not shown, the hybrid vehicle 1 includes a power supply voltage VB of the DC power supply B, a load current IL flowing through the reactor L1 of the boost converter 200, an output voltage VH of the boost converter 200, a v-phase current Iv in each inverter, and A sensor for detecting the w-phase current Iw and the like is also provided. Each sensor output is input to the control device 100 via the control bus 11.

<Operation of Embodiment>
Next, the operation of this embodiment will be described.

<Vehicle stop determination process>
First, the vehicle stop determination process will be described with reference to FIG. FIG. 6 is a flowchart of the vehicle stop determination process. The vehicle stop determination process is a process for accurately determining whether or not the hybrid vehicle 1 is stopped in order to execute a phase short-circuit process to be described later. The vehicle stop determination process is realized by the HCVECU 110 executing a control program stored in the ROM.

  In FIG. 6, it is first determined whether or not a stop determination condition is satisfied (step S101). In the present embodiment, the stop determination condition is defined as the MG2 rotational speed Nmg2 being less than a predetermined value N1 and the brake pedal operation amount Tb being a predetermined value Tb1 or more. In addition, the case where this stop determination condition is satisfied is a case where “the number of rotations of the first electric motor is equal to or lower than the first threshold value and a stop operation for stopping the vehicle is performed” according to the present invention. It is an example.

  When the stop determination condition is not satisfied (step S101: NO), it is determined that the vehicle is in a non-stop state (that is, not in a stop state) (step S107). When it is determined that the vehicle is in the non-stop state, the stop determination flag is set to off. When it is determined that the vehicle is in a non-stop state, the vehicle stop determination process ends. Note that the vehicle stop determination process is a control that is repeatedly executed at a constant cycle, and after completion, the process returns to step S101 again.

  On the other hand, when the stop determination condition is satisfied (step S101: YES), it is determined whether or not the stop determination flag is off (step S102). If the stop determination flag is on (step 102: NO), the process returns to step S101.

  When the stop determination flag is off (step S102: YES), timer timing is started (step S103). The measurement time by the timer timing is a reference time set experimentally, empirically or theoretically in advance. When the timer timing is started, it is determined whether or not the state where the stop determination condition is satisfied is continued (step S104). If the stop determination condition is not satisfied during the timer timing (step S104: NO), the process proceeds to step S107.

  If the stop determination condition is satisfied (step S104: YES), it is determined whether or not the timer timing has ended (step S105). That is, in step S105, it is determined whether or not the state where the stop determination condition is satisfied continues for the reference time.

  If the timer timing has not ended (step S105: NO), that is, if the duration of the state in which the stop determination condition is satisfied is still less than the reference time, the process returns to step S104.

  When the timer timing ends (step S105: YES), it is determined that the hybrid vehicle 1 is stopped, and the stop determination flag is turned on (step S106). When the stop determination flag is turned on, the vehicle stop determination process ends.

<Phase short circuit treatment>
Next, the phase short-circuit process will be described with reference to FIG. FIG. 7 is a flowchart of the phase short circuit process. The phase short-circuit process is a process for controlling the operation of the above-described phase short-circuit control for reducing power consumption while the vehicle is stopped.

  In FIG. 7, it is first determined whether or not the stop determination flag is on (step S201). If the stop determination flag is on (step S201: YES), it is determined whether each inverter of the PCU 10 is under normal control (step S202). Note that the normal control according to the present embodiment refers to PWM control as described above. When the normal control is not being performed (step S202: NO), that is, when the phase short-circuit control described later is being performed, the process returns to step S201.

  On the other hand, when the stop determination flag is ON and normal control is being performed (step S202: YES), the HVECU 110 outputs a phase short-circuit command signal (step S203). When the phase short-circuit command signal is output, the phase short-circuit process ends. The phase short-circuit process is a process that is repeated at a predetermined cycle similarly to the vehicle stop determination process described above, and is restarted from step S201 after the end.

  When the phase short-circuit command signal is output to the control bus 11, phase short-circuit control is performed on the MG2 inverter 300 and the MG1 inverter 400 by the MG2 ECU 120 and the MG1 ECU 130, respectively, according to the phase short-circuit command signal. However, since FIG. 7 describes the operation of the HVECU 110, these operations are not displayed in FIG.

  The phase short-circuit control is performed for each inverter with a p-side switching element (that is, the first switching element or upper arm) and an n-side switching element (that is, the second switching element or lower) of each phase of U phase, V phase, and W phase. Arm) is turned off, and at least one of the other switching elements is turned on.

  For convenience, in the present embodiment, the p-side switching element is short-circuited, but any switching element may be selected. Alternatively, the control logic may be determined in advance so that one of the targets is a phase short circuit. Also, when executing phase short-circuit control, one-phase short-circuit control for short-circuiting a specific one of the p-side switching elements of each phase, two-phase short-circuit control for short-circuiting a specific two-phase, short-circuiting all three phases Any of the three-phase short-circuit control to be performed may be selected. Alternatively, the control logic may be determined in advance so that any one is executed.

  When phase short circuit control is performed on the MG2 inverter 300 and the MG1 inverter 400, the switching operation does not occur in each inverter, so that power consumption can be reduced.

  On the other hand, when the stop determination flag is OFF in step 201 (step S201: NO), it is determined whether or not phase short-circuit control is being executed (step S204). When the phase short-circuit control is not being executed (step S204: NO), the process returns to step S201.

  When the phase short-circuit control is being executed in step S204 (step S204: YES), the HVECU 110 outputs a return command signal (step S205). When the return command signal is output to the control bus 11, the waiting time Tdly begins to elapse (step S206). The waiting time completion Tdly corresponds to an elapsed time after the return command signal is output.

  When counting of the standby time Tdly is started, it is determined whether or not the standby time Tdly is equal to or greater than the determination reference time Tdly1 (step S207). The determination reference time Tdly1 is an example of the “predetermined time” according to the present invention, and is set as a time sufficient for both the MG2 inverter 300 and the MG1 inverter 400 to be ready to start PWM control.

  As already described, the phase short-circuit control is a control in which the switching element provided in each inverter is fixed on or off, and is fundamentally different from the PWM control in which the switching element provided in each inverter is constantly switched at a high speed. It is a different control. Therefore, even if the switching from the PWM control to the phase short-circuit control is completed relatively quickly, the switching from the phase short-circuit control to the PWM control (that is, the return to the normal control) takes, for example, several tens of milliseconds. There is a delay.

  This delay time does not match between the MG2 inverter 300 and the MG1 inverter 400 even if a return command signal is simultaneously output from the HVECU 110 to the MG2ECU 120 and the MG1ECU 130. The determination reference time Tdly1 in the present embodiment is a time for absorbing variations in preparation completion times among the plurality of motor generators.

  This time delay is caused by, for example, a signal transmission delay or the necessity of shutdown for each inverter. Supplementing the latter, when switching from phase short-circuit control to PWM control, all switching elements are temporarily turned off so that there is no short-circuit in which both the p-side switching element and the n-side switching element are simultaneously turned on. A so-called shutdown control is required. The time required for this shutdown control does not vary greatly from inverter to inverter, but if the overall required time increases, the difference in time when preparations are completed between the inverters tends to increase.

  When the standby time Tdly is less than the determination reference time Tdly1 (step S207: NO), the process is set to a standby state in step S207. When the standby time Tdly is equal to or greater than the determination reference time Tdly1 (step S207: YES), the HVECU 110 outputs the torque command value TR2 of the motor generator MG2 to the MG2ECU 120 and the torque command value TR1 of the motor generator MG1 to the MG1ECU 130. Are started (step S208). When the output of the torque command value is started, the return to the PWM control is completed, and the phase short-circuit process ends. The phase short-circuit process is performed as described above.

<Effect of phase short-circuit treatment>
Next, the effect of such a phase short circuit process will be described. First, a case where a torque command value is output simultaneously with the return command signal will be described with reference to FIG. 8 as a comparative example to be used for comparison with the phase short-circuit process according to the present embodiment. FIG. 8 is a diagram illustrating the time transition of the torque of each motor generator in the return transition period from the phase short-circuit control to the normal control according to the comparative example.

  In FIG. 8, the upper part shows the time transition of the MG2 torque Tmg2, and the lower part shows the time transition of the MG1 torque Tmg1.

  In FIG. 8, it is assumed that the return command signal and the torque command value are simultaneously output at the illustrated time t1.

  First, the MG2 inverter 300 corresponding to the motor generator MG2 will be described. In this case, the time when the preparation for execution of the PWM control is completed in the MG2 inverter 300 is the illustrated time t4. That is, for the period from time t1 to t4, the torque command value (broken line) increases after time t1, whereas the actual MG2 torque Tmg2 (see solid line) is zero. When preparation for execution of PWM control is completed at time t4, the MG2 inverter 300 is driven to follow the torque command value TR2 at that time, and at time t5, the torque command value TR2 and the actual MG2 torque Tmg2 match. To do.

  Next, the MG1 inverter 400 corresponding to the motor generator MG1 will be described. The time when the preparation for executing the PWM control is completed in the MG1 inverter 400 is the illustrated time t2. That is, for the period from time t1 to t2, the torque command value (broken line) increases after time t1, whereas the actual MG1 torque Tmg1 (see solid line) is zero. When preparation for execution of PWM control is completed at time t2, the MG1 inverter 400 is driven to follow the torque command value TR1 at that time, and at time t3, the torque command value TR1 and the actual MG1 torque Tmg1 match. To do.

  Here, when the MG2 torque Tmg2 and the MG1 torque Tmg1 are compared on the time axis, the time at which the preparation for execution of the PWM control is completed differs between the MG2 inverter 300 and the MG1 inverter 400. In the illustrated period POD1 up to the time t5, the relationship between the torques of both largely deviates from the target. Therefore, during this period POD1, the torque supplied to the output shaft OS of the power split mechanism PG, that is, the sum of the direct torque that is a part of the engine torque Te and the MG2 torque Tmg2 fluctuates greatly, and from the target Is also significantly different. As a result, the comfort of the hybrid vehicle 1 is reduced.

  In particular, in a vehicle configuration such as the hybrid vehicle 1 in which a plurality of motor generators are connected to the power split mechanism PG as a differential mechanism with two degrees of rotation, unless the reaction force of the engine torque Te is borne by the MG1 torque Tmg1. The direct achievement of the engine torque Te cannot be transmitted to the output shaft OS. Accordingly, the deviation of the MG1 torque Tmg1 from the target value is directly related to the torque fluctuation of the output shaft OS. On the other hand, also for motor generator MG2 capable of applying MG2 torque Tmg2 to output shaft OS, the fluctuation of MG2 torque Tmg2 is directly connected to the torque fluctuation of output shaft OS.

  That is, if the MG1 torque Tmg1 and the MG2 torque Tmg2 deviate from the torque command value TR originally determined in view of the efficiency of the power source including the engine EG and the motor generators MG1 and MG2, torque shock due to torque fluctuation or torque shortage The reduction in power performance due to the above tends to become obvious, and the comfort of the hybrid vehicle 1 tends to greatly decrease.

  Next, the phase short-circuit process according to the present embodiment will be described with reference to FIG. FIG. 9 is a diagram illustrating the time transition of the torque of each motor generator in the transitional transition period from the phase short-circuit control to the normal control according to the present embodiment. In the figure, the same reference numerals are given to the same portions as those in FIG. 8, and the description thereof will be omitted as appropriate.

  In FIG. 9, both the MG2 inverter 300 and the MG1 inverter 400 start preparation for return to PWM control when the return command signal is output at the illustrated time t1. However, since HVECU 110 does not yet output a torque command value, MG2 torque Tmg2 and MG1 torque Tmg1 remain zero.

  Here, according to the phase short-circuit process according to the present embodiment, the determination reference time Tdly as a time sufficient for both the MG2 inverter 300 and the MG1 inverter 400 to start the PWM control has elapsed. A torque command value is supplied at the time. For convenience, FIG. 9 shows a case where this time is equal to the illustrated time t4 when the preparation for execution of PWM control is completed in the MG2 inverter 300. That is, in FIG. 9, a torque command value is output at time t4 (see broken line).

  By doing so, the MG2 torque Tmg2 and the MG1 torque Tmg1 change while maintaining the relative relationship (relative ratio) between the torque command values (see the solid line). As a result, the deterioration of the comfort of the hybrid vehicle 1 seen in the comparative example does not occur.

  Here, an example is shown in which the torque command value corresponding to the time t4 when it is assumed that the torque command value is supplied at the illustrated time t1 at the illustrated time t4. However, from the viewpoint of suppressing a decrease in comfort, the torque command value may rise from zero at the illustrated time t4. That is, the torque command value rising from time t1 in FIG. 8 may be shifted in the time axis direction until time t4.

  Thus, according to the present embodiment, the output timing of the return command signal and the output timing of the torque command value are different so that torque output corresponding to the torque command value can be made in each of the motor generators MG2 and MG1. It has been tightened. Accordingly, it is possible to suppress a decrease in comfort of the hybrid vehicle 1 due to one motor generator being in an operating state prior to the other.

  In addition, the effect of the phase short-circuit process according to the present embodiment is not impaired when any of the one-phase short-circuit control, the two-phase short-circuit control, and the three-phase short-circuit control is executed as the phase short-circuit control. However, from the viewpoint of processing required to return to PWM control, the phase short-circuit processing according to the present embodiment is more effective when single-phase short-circuit control or two-phase short-circuit control is executed.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. A vehicle control apparatus that includes such a change is also applicable. Moreover, it is included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 10 ... PCU, 100 ... Control apparatus, 110 ... HVECU, 120 ... MG2ECU, 130 ... MG1ECU, 200 ... Boost converter, 300 ... Inverter for MG2, 400 ... Inverter for MG1, B ... DC power supply, MG1, MG2 Motor generator.

Claims (1)

A plurality of three-phase AC motors including a first motor that rotates synchronously with a drive shaft of the vehicle;
Each of the plurality of three-phase AC motors includes a first switching element and a second switching element electrically connected in series corresponding to each of the three phases, and is supplied to each of the plurality of three-phase AC motors A vehicle control device that controls a vehicle including a power converter that converts electric power from direct current to alternating current,
In normal control, first control means for controlling the power converter based on a torque command value corresponding to each of the plurality of three-phase AC motors set based on driving conditions of the vehicle;
Determining means for determining that the vehicle is stopped when the rotation speed of the first electric motor is equal to or lower than a first threshold value and a stop operation for stopping the vehicle is being performed;
When it is determined by the determination means that the vehicle is stopped, one of the first switching element and the second switching element is turned off, and the first switching element and the second switching element are turned off. Second control means for controlling the power converter so as to be in a predetermined state in which at least one of the other elements is turned on;
Third control means for outputting the torque command value after a predetermined time has elapsed from the output of the return command signal when the power converter in the predetermined state is returned to the normal control in response to a predetermined return command signal; A vehicle control device comprising the vehicle control device.

Images