JP2018083486A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device that suppresses rotation of a motor generator while maintaining an engine running and protects an inverter from overvoltage when an abnormality occurs in a main machine power supply.SOLUTION: A vehicle control device 50 is applied to a hybrid vehicle 901 including an engine 70 and an MG 60 which are power sources and a main machine battery 20 capable of exchanging power with the MG 60 via an inverter 40. The vehicle control device 50 can control an operation of the engine 70 and the MG 60 and can control a power transmission between the engine 70 and the MG 60. When abnormality of the main machine battery 20 is detected, the vehicle control device 50 shuts off a power supply relay 21 provided between the main machine battery 20 and the inverter 40, and stops a power running operation of the MG 60. Then, while maintaining a vehicle running by the engine 70, the vehicle control device 50 executes "MG rotation suppression processing" that eliminates at least one factor of increasing the MG rotation number through an operation of a vehicle and suppresses a rotation of the MG 60.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle control apparatus that controls a hybrid vehicle.

2. Description of the Related Art Conventionally, in a hybrid vehicle including an engine and a motor generator, a technique is known in which a speed change operation is performed when a main battery is abnormal, and the motor generator is regeneratively generated while the vehicle is driven by the engine. By controlling the voltage generated at this time, the power to the auxiliary battery is stably supplied.
For example, a control apparatus for a hybrid vehicle described in Patent Document 1 is a dual-clutch type vehicle including an odd-numbered first clutch and an even-numbered second clutch, and performs a downshift operation to the lowest gear position when the main battery is abnormal. To do.

Japanese Patent No. 5855603

In the prior art disclosed in Patent Document 1, when the rotation of the motor generator increases due to a downshift operation or the like during high-speed traveling, an overvoltage may be applied to the inverter due to an increase in regenerative power. As a result, the elements constituting the inverter may be damaged.
The present invention has been created in view of the above points, and an object of the present invention is to control a vehicle that suppresses rotation of a motor generator and protects an inverter from overvoltage while maintaining engine running when the main engine power supply is abnormal. To provide an apparatus.

  A vehicle control apparatus according to the present invention is a hybrid vehicle including an engine (70) and a motor generator (60), which are power sources, and a main engine power source (20) capable of transferring power to and from the motor generator via an inverter (40). (901, 902). This vehicle control device controls the operation of the engine and the motor generator, and can control at least one of the power transmission between the engine and the motor generator or the power transmission between the motor generator and the axle (96). It is.

  When an abnormality of the main engine power supply is detected, this vehicle control device cuts off the power supply relay (21) provided between the main engine power supply and the inverter and stops the power running operation of the motor generator. The vehicle control device suppresses the rotation of the motor generator by eliminating at least one factor that increases the rotation speed of the motor generator (hereinafter referred to as “MG rotation speed”) by the operation of the vehicle while maintaining the vehicle running by the engine. “MG rotation suppression processing” is executed.

Specifically, the vehicle control device suppresses the rotation of the engine that is directly transmitted to the motor generator or indirectly transmitted as the vehicle travels in the MG rotation suppression process, or the motor generator Suppresses rotation directly.
Examples of MG rotation suppression processing include prohibition of traction control cut, prohibition of manual transmission mode, prohibition of deceleration blipping, prohibition of downshifting at high speeds, and the like.

In the present invention, the engine running is maintained while stopping the power running operation of the motor generator when the main battery is abnormal, so that retreat running (so-called limp home) is possible.
Then, by executing the MG rotation suppression process, an increase in the MG rotation speed due to the rotation of the engine or axle transmitted to the motor generator is avoided. Thereby, the element of an inverter can be appropriately protected from the overvoltage applied to an inverter by regenerative power generation.

  Moreover, the inverter control part of a vehicle control apparatus performs voltage control, when predetermined execution conditions are satisfied about MG rotation speed and a capacitor | condenser voltage as inverter control mode. Thereby, for example, since desired power can be supplied from the inverter to the auxiliary battery, functions such as a starter and an electric power steering device can be ensured during the retreat travel. On the other hand, when the voltage control execution condition is not satisfied, the inverter control unit executes gate cutoff.

1 is a schematic configuration diagram of a vehicle to which a vehicle control device of a first embodiment is applied. The block diagram of the control system in the vehicle of FIG. The main flowchart which shows the whole process at the time of main machine battery abnormality. FIG. 4 is a sub flowchart of the MG rotation suppression process of FIG. 3. The characteristic view of MG rotation speed and capacitor voltage in voltage control and gate interruption | blocking. The figure which shows the switching of voltage control and gate interruption | blocking by the change of MG rotation speed. The time chart which shows the 1st operation example at the time of main machine battery abnormality. The time chart which shows the 2nd operation example at the time of main machine battery abnormality. The schematic block diagram of the vehicle of an axle split system to which the vehicle control apparatus of 2nd Embodiment is applied. The figure which shows the structural example of MG rotation suppression in the vehicle of an axle split system.

Hereinafter, a plurality of embodiments of a vehicle control device will be described based on the drawings. In a plurality of embodiments, substantially the same configuration is denoted by the same reference numeral and description thereof is omitted. The first and second embodiments are collectively referred to as “this embodiment”.
The vehicle control device of the present embodiment is applied to a hybrid vehicle including an engine and a motor generator (hereinafter “MG”) as power sources. The first embodiment is applied to a normal hybrid vehicle in which the engine and the MG cooperate to drive the same drive wheel. The second embodiment is applied to an axle split type vehicle in which an engine and an MG drive different drive wheels.

(First embodiment)
The vehicle control apparatus of 1st Embodiment is demonstrated with reference to FIGS.
As shown in FIG. 1, a vehicle control system 10 applied to a vehicle 901 includes an engine 70, an MG 60, a main battery 20, an inverter 40, power transmission clutches 81 and 82, a transmission 84, and a vehicle control device 50. Etc.
The engine 70 converts thermal energy generated by burning fuel into rotational driving force.
The MG 60 performs a power running operation for generating torque by consuming electric power supplied from the main battery 20, and a regenerative operation for regenerating power generated by the torque transmitted from the engine 70 or the drive shaft 94 side to the main battery 20. Do. The MG 60 of this embodiment is a permanent magnet type synchronous three-phase AC motor generator.

The main battery 20 as the “main power supply” is constituted by a chargeable / dischargeable secondary battery such as a nickel metal hydride battery or a lithium ion battery. The positive electrode of the main battery 20 is connected to the high potential line P, and the negative electrode of the main battery 20 is connected to the low potential line N.
The main battery 20 may be referred to as a “high voltage battery”, and an auxiliary battery 32 described later may be referred to as a “low voltage battery”. Further, instead of the battery, a power storage device such as an electric double layer capacitor may be used as the main power source.

  A power relay 21 that can cut off the power path is provided between the main battery 20 and the inverter 40. The power supply relay 21 corresponds to a so-called system main relay, and includes a high potential side relay 22 provided on the high potential line P and a low potential side relay 23 provided on the low potential line N. The high potential side relay 22 and the low potential side relay 23 may be either a mechanical relay or a semiconductor relay.

  Inverter 40 mutually converts DC power on main battery 20 side and three-phase AC power on MG 60 side. As shown in FIG. 2, the inverter 40 includes switching elements 41-46 of three-phase upper and lower arms. Specifically, switching elements 41, 42, and 43 are U-arm, V-phase, and W-phase upper arm switching elements, respectively, and switching elements 44, 45, and 46 are respectively under the U-phase, V-phase, and W-phase. This is an arm switching element. The switching elements 41 to 46 of the present embodiment are IGBTs (insulated gate bipolar transistors). Further, the switching elements 41 to 46 are accompanied by flywheel diodes that allow energization from the low potential emitter side to the high potential collector side.

A capacitor 25 for smoothing the input voltage is provided on the main battery 20 side of the inverter 40. A voltage across the capacitor 25, that is, a potential difference between the high potential line P and the low potential line N is referred to as a capacitor voltage Vc. If the capacitor voltage Vc exceeds the upper limit of the withstand voltage, elements such as the switching elements 41 to 46 of the inverter 40 may be damaged.
In the present embodiment, for example, the capacitor voltage Vc may be monitored by a voltage sensor (not shown).

In the configuration example shown in FIG. 1, the DCDC converter 30 is connected to a path branched from the power path between the power supply relay 21 and the inverter 40. Note that the illustration of the DCDC converter 30 is omitted in FIG.
DCDC converter 30 steps down the high voltage power of main battery 20 and outputs the low voltage power. The auxiliary battery 32 is composed of a secondary battery such as a lead storage battery, for example, and is charged with the low-voltage power output from the DCDC converter 30. The auxiliary battery 32 supplies low voltage power to various auxiliary loads 33 of the vehicle. The auxiliary machine load 33 includes, for example, an engine starter, an electric power steering device, a brake actuator, and the like that have functions necessary for retreat travel.

The engine-side clutch 81 is provided on the output shaft 71 of the engine 70, and interrupts power transmission between the engine 70 and the MG 60.
The axle side clutch 82 is provided on the drive shaft 94 on the output side of the MG 60, and interrupts power transmission between the MG 60 and the axle 96. The transmission 84 can change the power transmitted to the drive shaft 94. The functions of the axle side clutch 82 and the transmission 84 may be configured as, for example, a dual clutch transmission (abbreviated as “DCT”).
The driving force transmitted to the drive shaft 94 on the output side of the transmission 84 is transmitted to the axle 96 via the differential gear 95 to rotate the drive wheels 98.

  As shown in FIG. 2, the vehicle control device 50 includes a plurality of individual ECUs 52, 54, 57, 58 and a general ECU 51 that controls them, and comprehensively performs various controls related to driving of the vehicle. Each ECU is composed mainly of a microcomputer or the like, and can transmit and receive information via a communication network such as CAN. The processing in each ECU may be software processing by a CPU executing a program stored in advance in a substantial memory device such as a ROM, or may be hardware processing by a dedicated electronic circuit.

In FIG. 2, the vehicle control device 50 includes a general ECU 51, a battery ECU 52, an MG-ECU 54, an engine ECU 57, and a transmission ECU (“T / M-ECU” in the figure) 58. The actual vehicle further includes individual ECUs other than those shown in FIG. 2, but FIG. 2 shows only the configuration and signal input / output related to the main operation of this embodiment.
Only the functions related to the main operation of this embodiment will be described below. Further, the function sharing by each ECU is not limited to the configuration shown below, and any ECU may be able to realize the same function as the entire vehicle control device 50.

The overall ECU 51 acquires each piece of information from the battery ECU 52, the MG-ECU 54, the engine ECU 57, and the transmission ECU 58. Further, the overall ECU 51 acquires information on the accelerator opening, the shift position, the vehicle speed, and the like from an accelerator sensor, a shift switch, a vehicle speed sensor, and the like (not shown). The overall ECU 51 controls the entire vehicle 901 based on the acquired information. Then, the overall ECU 51 transmits command signals to the MG-ECU 54, the engine ECU 57, and the transmission ECU 58, respectively.
Further, in a vehicle capable of executing traction control (hereinafter referred to as “TRC”) that suppresses rotation of a wheel having a relatively high rotational speed, the overall ECU 51 prohibits “TRC cut” that causes the driver to arbitrarily lose the TRC function. can do.

The battery ECU 52 acquires main battery information such as voltage, current, temperature, and SOC of the main battery 20, and monitors the state of the main battery 20 so that the SOC of the main battery 20 is within a predetermined range. Further, the battery ECU 52 detects an abnormality of the main unit battery 20 based on the acquired main unit battery information.
The abnormality of the main battery 20 includes a voltage abnormality in which the voltage deviates from the normal range, an overcurrent abnormality in which the current exceeds the upper limit value, and an SOC abnormality in which the SOC deviates from the normal range. When an abnormality in main unit battery 20 is detected, battery ECU 52 cuts off power supply relay 21 and disconnects main unit battery 20 from inverter 40 and MG 60.

The MG-ECU 54 as the “inverter control unit” notifies the general ECU 51 of information on the actual MG torque Tm and the actual MG rotation speed Nm. The MG-ECU 54 controls the operation of the MG 60 by operating the switching elements 41-46 of the inverter 40 in accordance with the MG torque command Tm ^* and the MG rotational speed command Nm ^* transmitted from the overall ECU 51.
Here, the MG-ECU 54 acquires, for example, the motor current Im detected by the current sensor 64 and the electrical angle θ detected by the rotation angle sensor 65. Then, the MG-ECU 54 may calculate the MG torque Tm using the dq-axis current obtained by coordinate conversion of the phase current, or may acquire the MG torque Tm detected by a torque sensor (not shown). The MG-ECU 54 may calculate the MG rotation speed Nm by differentiating the detected value of the electrical angle θ with respect to time, or may estimate the MG rotation speed Nm based on the estimated position in the position sensorless configuration. .

The MG-ECU 54 causes the inverter 40 to generate desired power by PWM driving the inverter 40 based on the voltage command value calculated by the current feedback control and the torque feedback control during the normal control in the power running operation. To supply.
Further, regarding the inverter control mode in the regenerative operation after the power supply relay 21 is shut off, the MG-ECU 54 executes “voltage control” or “gate shut-off”.

  In the “voltage control” mode, the MG-ECU 54 operates the operations of the plurality of switching elements 41-46 of the inverter 40 to control the capacitor voltage Vc. In the “gate cut-off” mode, the MG-ECU 54 turns off all of the plurality of switching elements 41-46 of the inverter 40. In the state where the gate is cut off, the current from the MG 60 side flows from the low potential side to the high potential side via the flywheel diode associated with the switching element 41-46.

The engine ECU 57 notifies the general ECU 51 of information on the actual engine torque Te and the actual engine speed Ne. Further, the engine ECU 57 controls the operation of the engine 70 by operating the injection amount and the injection timing of the fuel injection valve in accordance with the engine torque command Te ^* transmitted from the general ECU 51.
The engine ECU 57 can inhibit deceleration blipping that increases the engine speed Ne when the vehicle decelerates, for example, in cooperation with an accelerator ECU (not shown).

  The transmission ECU 58 notifies transmission information (“T / M information” in the figure) to the general ECU 51. The transmission ECU 58 controls the operations of the clutches 81 and 82 and the transmission 84 in accordance with the clutch and shift command transmitted from the general ECU 51. In vehicle 901, transmission ECU 58 controls power transmission between engine 70 and MG 60 and power transmission between MG 60 and axle 96.

  For example, the transmission ECU 58 instructs the clutches 81 and 82 to switch between the engaged state, the semi-engaged state, and the released state. Further, the transmission ECU 58 instructs the transmission 84 to switch the shift position or prohibits downshifting. Further, when vehicle 901 is a vehicle that can switch between an automatic transmission mode and a manual transmission mode (hereinafter referred to as “MT mode”), transmission ECU 58 can prohibit the MT mode.

  By the way, after the abnormality of the main battery 20 is detected and the power supply relay 21 is cut off, the electric power generated by the MG 60 is not regenerated in the main battery 20 but is charged in the capacitor 25, so that the capacitor voltage Vc increases. At this time, when the MG rotation speed Nm is high and the regenerative power generation amount is large, a load dump in which the capacitor voltage Vc becomes excessive occurs. The overvoltage due to the load dump may damage the switching elements 41-46, the capacitor 25, the elements of the DCDC converter 30, and the like.

  Therefore, the vehicle control device 50 cuts off the power supply relay 21 due to an abnormality of the main battery 20, and then maintains the vehicle traveling by the engine 70 and enables retreat traveling, while suppressing an increase in the MG rotation speed Nm. "MG rotation suppression process" is executed. In this MG rotation suppression process, the vehicle control device 50 eliminates at least one factor that increases the MG rotation speed due to the operation of the vehicle. Specifically, vehicle control device 50 suppresses rotation of engine 70 that is directly transmitted to MG 60 or indirectly transmitted as the vehicle travels, or directly suppresses rotation of MG 60. .

Subsequently, the main engine battery abnormality process by the vehicle control device 50 will be described with reference to the main flowchart of FIG. 3, the sub-flowchart of FIG. 4, and FIGS. 5 and 6. In the description of the flowchart, the symbol S represents “step”.
After the ready ion of S1, the MG-ECU 54 normally controls the inverter 40 in S2. The normal control by S2 is continued until the main battery abnormality is detected by the battery ECU 52 in S3.

  When the main engine battery abnormality is detected in S3, in S4, the current MG torque Tm is compared with the threshold value Tmth to determine whether the current operating state of the MG 60 is power running or regeneration. When the MG torque Tm is greater than the threshold value Tmth and the answer is YES in S4, it is determined to be power running and the process proceeds to S5. When the MG torque Tm is equal to or less than the threshold value Tmth and NO in S4, the regeneration is determined and the process proceeds to S6.

  When the main engine battery abnormality is detected during the power running operation of MG 60, vehicle control device 50 turns off power supply relay 21 in S5. At this time, since the capacitor voltage Vc decreases, a diagnosis signal of the voltage sensor is generated in the normal control. However, in this process, since the power supply relay 21 is intentionally turned off, a diagnosis signal is unnecessary. Therefore, after the diagnosis signal is masked in S7, the MG-ECU 54 waits for reception of a voltage control command. And if MG-ECU54 receives a voltage control command and it is judged as YES by S8, it will transfer to the MG rotation suppression process of S10, and the gate interruption | blocking of S21.

  On the other hand, if the main engine battery abnormality is detected during the regenerative operation of MG 60, when power relay 21 is turned off in S6, the voltage of inverter 40 rises due to the power generated by MG 60 and a load dump occurs. It is necessary to shut off. Therefore, at the same time as the power relay is turned off in S6, the MG rotation suppression process in S10 and the gate cutoff in S21 are executed.

As shown in FIG. 4, in the MG rotation suppression process in S10, the following three processes are performed in S11.
(A) TRC cut prohibition flag ON
(B) MT mode prohibition flag ON
(C) Deceleration blipping prohibition flag ON
Further, when the vehicle speed exceeds the vehicle speed threshold value and YES in S12, the process (d) is performed in S13.
(D) Downshift prohibited When the vehicle speed is equal to or lower than the vehicle speed threshold value and NO in S12, downshift is permitted in S14.

Each MG rotation suppression process is performed for the following purpose.
(A) In TRC, when a certain wheel has an extremely higher rotational speed than other wheels, it is determined that the wheel has idled, and control for suppressing the rotation of the wheel is performed. If this function is cut, the rotation of the idle wheel may be transmitted to increase the MG rotation speed. Therefore, the TRC cut that can increase the MG rotation speed is prohibited.
(B) In the MT mode, the vehicle control device 50 may exceed the controllable range, and the MG rotation speed may increase due to the driver's manual operation. Therefore, the MT mode that can increase the MG rotation speed is prohibited.

(C) When the driver depresses the accelerator during the deceleration shift and performs the deceleration blipping that increases the engine speed, the MG speed may increase due to the transmission of the engine speed. Therefore, deceleration blipping, which can increase the MG speed, is prohibited regardless of the vehicle speed.
(D) By prohibiting the downshift itself particularly during high-speed traveling, it is possible to prevent an increase in the engine speed accompanying the downshift and an accompanying increase in the MG speed.

Returning to FIG. 3, S21 to S24 are steps relating to switching of inverter control.
In S21, the MG-ECU 54 gates the inverter 40. That is, immediately after the power supply relay 21 is turned off in S5 or S6, the inverter 40 is once gate-cut.
Next, in S22, whether or not the voltage control execution condition is satisfied is determined. It is determined that the voltage control execution condition is satisfied when the MG rotation speed Nm and the capacitor voltage Vc are within the respective upper and lower limit values. Here, when the upper limit value of the MG rotation speed Nm is expressed as NmH, the lower limit value is expressed as NmL, the upper limit value of the capacitor voltage Vc is expressed as VcH, and the lower limit value is expressed as VcL, both equations (1) and (2) hold. When YES, it is determined YES in S22.
NmL ≦ Nm ≦ NmH (1)
VcL ≦ Vc ≦ VcH (2)

If the voltage control execution condition is not satisfied and the answer is NO in S22, the process returns to before S21 and the gate interruption is continued.
When the voltage control execution condition is satisfied and YES in S22, the presence or absence of ready-off is determined in S23. If ready-off, YES is determined in S23 and the processing routine ends. If it is not ready-off and it is judged as NO in S23, it will transfer to S24.
In S24, the MG-ECU 54 drives the inverter 40 to execute voltage control. Thereafter, the process returns to before S22, and whether or not the voltage control execution condition is satisfied is repeatedly determined.

As shown in FIG. 5, when the gate is cut off, the MG rotation speed Nm and the capacitor voltage Vc have a positive correlation, and the capacitor voltage Vc increases as the MG rotation speed Nm increases.
On the other hand, the voltage control can be executed only in a region where the MG rotation speed Nm is between the lower limit value NmL and the upper limit value NmH, and the capacitor voltage Vc is between the lower limit value VcL and the upper limit value VcH. The capacitor voltage Vc is controlled in accordance with a command from the MG-ECU 54.

Further, in practical use, there is a problem of preventing hunting when the MG rotation speed Nm changes across the MG rotation speed upper limit value NmH in the voltage control execution condition region. In the present embodiment, as shown in FIG. 6, the hysteresis of control mode switching is set to the MG rotation speed Nm.
That is, the MG rotation speed Nm increases, and the acceleration switching speed Nx + that is switched from voltage control to gate cutoff is set to a value that is equal to or lower than the upper limit value NmH. On the other hand, the deceleration switching rotational speed Nx− at which the MG rotational speed Nm decreases and the gate control is switched to the voltage control is set to a value smaller than the acceleration switching rotational speed Nx +. Thereby, when the MG rotation speed Nm is in the vicinity of the upper limit value NmH, it is possible to prevent the control from becoming unstable due to frequent switching between the voltage control and the gate cutoff.

  Next, with reference to the time charts of FIG. 7 and FIG. 8, an operation example of the main battery abnormality process by the vehicle control device 50 will be described. Times t0, t1, and t3 indicated by common symbols on the time axes in the drawings mean timings corresponding to each other. The vertical dashed arrows in each figure indicate the relationship between a change in one state and a change in another state. Of the above-described MG rotation suppression processing, “TRC cut prohibition” and “MT mode prohibition” are shown in common in FIGS. 7 and 8, and “downshift prohibition during high-speed driving” is shown in FIG. Instead of or in addition to these, an MG rotation suppression process such as “prohibited deceleration blipping” may be executed.

FIG. 7 shows a first operation example. In the lower part of FIG. 7, as a comparative example, an operation in the case where “prohibition of downshift at high speed” is not executed is indicated by a two-dot chain line.
In the initial stage before time t0, the inverter 40 is normally controlled. Capacitor voltage Vc is between lower limit value VcL and upper limit value VcH, and MG rotational speed Nm is between lower limit value NmL and upper limit value NmH. The position of the transmission gear is “5th speed”.

At time t0, a main battery abnormality occurs and the power relay 21 is turned off. Thereafter, the capacitor voltage Vc falls below the lower limit value VcL and decreases to 0 by the discharge of the capacitor 25.
Assuming that the MG 60 was in a power running operation before time t0, the MG-ECU 54 receives a voltage control command at time t1, and the vehicle control device 50 prohibits the TRC cut and MT mode as MG rotation suppression processing. Thereby, some of the factors that increase the MG rotation speed Nm by the operation of the vehicle are eliminated.
At this time, the MG-ECU 54 sets the inverter control mode to gate cutoff.

After time t1, the capacitor voltage Vc increases due to regenerative power generation of the MG 60, and reaches the lower limit value VcH at time t3. Further, since the MG rotation speed Nm is between the lower limit value NmL and the upper limit value NmH, the voltage control execution condition is satisfied. Therefore, MG-ECU 54 switches the inverter control mode from gate cutoff to voltage control.
Thereafter, when the vehicle speed starts to decrease at time t5, in the comparative example, the clutch is released from the engaged state, and the transmission gear is downshifted from “5th speed” to “3rd speed”, for example, and then engaged again.
On the other hand, in this embodiment, if the vehicle speed is larger than the vehicle speed threshold value of S12 in FIG. 4, the downshift is prohibited and the transmission gear is maintained at "5th speed" while the clutch is engaged.

In the comparative example, with the downshift, the MG rotation speed Nm increases before and after time t5 and exceeds the upper limit value NmH, and the capacitor voltage Vc increases and exceeds the upper limit value VcH. Therefore, an overvoltage is applied to the inverter 40, The element may be damaged.
On the other hand, in this embodiment, by prohibiting the downshift, an increase in the MG rotation speed Nm can be suppressed, and an increase in the capacitor voltage Vc can be prevented. Therefore, the element of the inverter 40 can be appropriately protected from overvoltage.

FIG. 8 shows a second operation example. The operation until the main engine battery abnormality occurs at time t0, the TRC cut and MT mode are prohibited at time t1, and the inverter control mode is gate cut-off is the same as in FIG.
After time t1, the capacitor voltage Vc rises due to regenerative power generation of the MG 60. However, at time t2 earlier than time t3 when the capacitor voltage Vc reaches the lower limit value VcH, a situation occurs in which the MG rotation speed Nm exceeds the upper limit value NmH. Therefore, since the voltage control execution condition is not satisfied at time t3, the inverter control mode is continued with the gate shut off.

  Further, at time t2 when the MG rotational speed Nm exceeds the upper limit value NmH, the transmission ECU 58 of the vehicle control device 50 places the engine-side clutch 81 in a semi-engaged state so as to reduce the MG rotational speed Nm. Insufficient power transmission to MG60. When the MG rotation speed Nm falls below the upper limit value NmH at time t4, the transmission ECU 58 brings the engine side clutch 81 into the engaged state again. Note that the engaged state and the semi-engaged state may be intermittently repeated between time t2 and time t4.

After time t3, the capacitor voltage Vc is maintained between the lower limit value VcL and the upper limit value VcH. Thereby, the element of the inverter 40 can be appropriately protected from overvoltage.
Then, the voltage control execution condition is satisfied when the MG rotation speed Nm falls below the upper limit value NmH at time t4. Therefore, MG-ECU 54 switches the inverter control mode from gate cutoff to voltage control.

Further, in the configuration in which the DCDC converter 30 is connected in parallel with the inverter 40 as shown in FIG. 1, the low voltage power supply to the auxiliary battery 32 is achieved by driving the DCDC converter 30 simultaneously with the start of execution of the voltage control. It becomes possible. As a result, even if the main engine battery 20 is abnormal, the auxiliary machine load 33 can be driven using the regenerative power generated by the MG 60.
Thereby, the power supply from the auxiliary battery 32 to the auxiliary load 33 such as the starter or the electric power steering device can be continued during the retreat traveling.

(Second Embodiment)
A second embodiment will be described with reference to FIGS. 9 and 10. The second embodiment is applied to an axle split type vehicle 902 in which a wheel connected to the engine 70 and a wheel connected to the MG 60 are separated.
In the example shown in FIG. 9, the output shaft 71 of the engine 70 is connected to a drive shaft 91 via a transmission 83, and the drive shaft 91 is connected to a front wheel 97 that is a drive wheel via a differential gear 92 and an axle 93. It is connected. The MG 60 is connected to the rear wheel 98 via the axle 96. The inverter 40 converts the power of the main battery 20 and supplies it to the MG 60.
In other embodiments, the front wheels and the rear wheels may be reversed with respect to FIG.

As in the first embodiment, the vehicle control device 50 communicates signals with the main battery 20, the inverter 40, the MG 60, the engine 70, the transmission 83, and the like, and inputs various information and outputs command signals. .
In this configuration, when the main battery 20 becomes abnormal and the power running operation of the MG 60 is stopped, the front wheel 97 is driven by the engine 70 to cause the vehicle 902 to travel. Then, the MG 60 regeneratively generates power by following the front wheel 97 and rotating the rear wheel 98. If the voltage generated at this time is excessive, the element of the inverter 40 may be damaged, and therefore the vehicle control device 50 performs the MG rotation suppression process.

In this configuration, as one method, there is a method of decreasing the MG rotation speed Nm by lowering the rotational speed of the front wheels 97 driven by the engine 70 to reduce the vehicle speed. As another method, it is also effective to directly suppress the rotation of MG60.
FIG. 10 shows a configuration example of MG rotation suppression unique to an axle split type vehicle. Here, the driving configuration of the front wheel 97 by the engine 70 is the same as that in FIG. 9, and the illustration is omitted, and only the side of the rear wheel 98 connected to the MG 60 is illustrated. As described above, the present invention may be applied to a configuration in which the front wheels and the rear wheels are reversed.

  In the configuration shown in FIG. 10A, a clutch 82 is provided in the middle of the drive shaft 94 that connects the MG 60 and the differential gear 95. In a state in which the vehicle 902 is running at a constant vehicle speed by driving the engine 70, the vehicle control device 50 slips the clutch 82 to reduce the MG rotation speed Nm to the upper limit value NmH or less, and then performs voltage control. Execute.

  In the configuration shown in FIG. 10B, a clutch 82 and a transmission 84 are provided in the middle of the drive shaft 94 that connects the MG 60 and the differential gear 95. In a state in which the vehicle 902 is traveling at a constant vehicle speed by driving the engine 70, the vehicle control device 50 shifts the transmission 84 to the Hi gear and reduces the MG rotation speed Nm to the upper limit value NmH or less. Execute voltage control after that.

In the configuration shown in FIG. 10C, the clutch 96 is provided in the middle of the axle 97 that connects the MG 60 and the left and right rear wheels 98. In a state in which the vehicle 902 is running at a constant vehicle speed by driving the engine 70, the vehicle control device 50 slips the clutch 96 to reduce the MG rotation speed Nm to the upper limit value NmH or less, and then performs voltage control. Execute.
Thus, also in 2nd Embodiment, the effect similar to 1st Embodiment is acquired.

(Other embodiments)
(1) The specific example of the MG rotation suppression process is not limited to that exemplified in the above embodiment, and any process that eliminates the “factor that increases the rotation speed of the motor generator by the operation of the vehicle” is the MG rotation suppression process. included.

(2) The vehicle control apparatus of the present invention is not limited to a system including one motor generator, and may be applied to a system including two motor generators connected by a power split mechanism, for example. Further, the present invention can be applied to a system in which a part of regenerative power is supplied by a fuel cell.
As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

10 ... Vehicle control system 20 ... Main machine battery (main machine power supply),
21 ... Power relay,
40: Inverter,
50 ... Vehicle control device,
60 ... MG (motor generator),
70 ... Engine,
901, 902 ... vehicle,
96 ... Axle.

Claims (9)

Applicable to hybrid vehicles (901, 902) equipped with an engine (70) and a motor generator (60), which are power sources, and a main power source (20) capable of transmitting and receiving electric power to and from the motor generator via an inverter (40). And controls the operation of the engine and the motor generator, and controls at least one of power transmission between the engine and the motor generator or power transmission between the motor generator and the axle (96). A possible vehicle control device,
When an abnormality of the main unit power supply is detected,
A power relay (21) provided between the main power supply and the inverter is cut off to stop the power running operation of the motor generator;
A vehicle control device that performs MG rotation suppression processing that suppresses rotation of the motor generator by eliminating at least one factor that increases the rotation speed of the motor generator by operation of the vehicle while maintaining vehicle travel by the engine. In the MG rotation suppression process,
Suppressing rotation of the engine that is directly transmitted to the motor generator or indirectly transmitted as the vehicle travels, or
The vehicle control device according to claim 1, wherein rotation of the motor generator is directly suppressed. It is applied to vehicles that can execute traction control that suppresses the rotation of relatively fast wheels,
The vehicle control device according to claim 2, wherein in the MG rotation suppression process, a traction control cut that causes the driver to arbitrarily lose the traction control function is prohibited. Applies to vehicles that can switch between automatic transmission mode and manual transmission mode,
The vehicle control device according to claim 2 or 3, wherein manual transmission mode is prohibited in the MG rotation suppression processing.   5. The vehicle control device according to claim 2, wherein, in the MG rotation suppression process, deceleration blipping that increases the engine speed when the vehicle is decelerated is prohibited. Applied to a vehicle provided with a transmission (83, 84) capable of shifting the power transmitted between the engine and the motor generator or between the motor generator and the axle;
The vehicle control device according to any one of claims 2 to 5, wherein, in the MG rotation suppression process, when the vehicle speed exceeds a speed threshold value, a downshift of the transmission is prohibited. Applied to a vehicle including an engine side clutch (81) for intermittently transmitting power between the engine and the motor generator;
When the number of rotations of the motor generator exceeds a predetermined upper limit (NmH) after execution of at least one of the MG rotation suppression processes, the engine side clutch is brought into a half-engaged state, or The vehicle control device according to any one of claims 1 to 6, wherein control is performed so as to repeat the half-engaged state. An inverter control unit (54) for acquiring the detected or estimated rotation speed of the motor generator and controlling the operation of the inverter;
The inverter control unit
After the abnormality of the main engine power supply is detected and the power supply relay is cut off,
The rotation speed (Nm) of the motor generator is within a predetermined rotation speed range, and a capacitor voltage (Vc) that is a voltage across the capacitor (25) provided on the main power supply side of the inverter is a predetermined voltage. When in range, perform voltage control to control the capacitor voltage by operating a plurality of switching elements (41-46) of the inverter,
The vehicle control device according to any one of claims 1 to 7, wherein gate cutoff is performed to turn off all of the plurality of switching elements of the inverter under conditions other than the conditions for executing the voltage control. In the switching of the voltage control and the gate cutoff control mode according to the change in the rotation speed of the motor generator,
The deceleration switching rotational speed (Nx−) at which the control mode is switched when the rotational speed of the motor generator decreases is the speed increasing switching rotational speed (Nx +) at which the control mode is switched when the rotational speed of the motor generator increases. The vehicle control device according to claim 8, wherein the vehicle control device is set to a smaller value.

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