JP2017061183A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately control an electric motor even when a current sensor is broken.SOLUTION: A vehicular control device includes: a first motor generator MG1 coupled to an engine 12; a second motor generator MG2 coupled to a driving wheel 18; a battery 25 electrically connected to both of the first motor generator MG1 and the second motor generator MG2; a first current sensor Se1 for detecting a first current value of the first motor generator MG1; a second current sensor Se2 for detecting a second current value of the second motor generator MG2; a third current sensor Seb for detecting a third current value of the battery 25; a current estimation section 40 for estimating the first current value as an estimated current value on the basis of the second current value and the third current value; a first motor control section 32 for controlling the first motor generator MG1 on the basis of the estimated current value; and a second motor control section 33 for maintaining a control target value of the second motor generator MG2 at a constant level.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle control device including a first electric motor and a second electric motor.

  A hybrid vehicle including a plurality of electric motors has been developed (see Patent Documents 1 to 3). As an electric motor mounted on such a vehicle, there is a power generation motor connected to an engine, and a traveling motor connected to drive wheels. By the way, when controlling an electric motor such as a power generation motor or a traveling motor, it has been necessary to detect a current value of the electric motor using a current sensor. When a failure occurs in such a current sensor, it is impossible to accurately grasp the current value, and it is difficult to appropriately control the electric motor. Therefore, when a failure occurs in some of the plurality of current sensors provided in the electric motor, a control technology for operating the electric motor by combining detection signals from other normal current sensors and the position sensor of the rotor. Has been proposed (see Patent Document 4).

JP 2000-220557 A Japanese Patent Laid-Open No. 10-331749 JP 2003-20981 A JP 2009-18695 A

  However, in the hybrid vehicle described in Patent Document 4, it is difficult to control the electric motor when all current sensors provided in the electric motor fail, that is, when the current value flowing through the electric motor cannot be grasped at all. It was. Thus, even when the current value of the electric motor cannot be grasped due to the failure of the current sensor, it is required to appropriately control the electric motor from the viewpoint of ensuring the minimum traveling performance in the hybrid vehicle. It was.

  An object of the present invention is to appropriately control an electric motor even when a current sensor fails.

  The vehicle control device according to the present invention is electrically connected to both the first electric motor connected to the engine, the second electric motor connected to the drive wheels, and the first electric motor and the second electric motor. An electric storage device connected to the first electric motor; a first current sensor that detects a first current value of the first electric motor; a second current sensor that detects a second current value of the second electric motor; A third current sensor that detects a third current value; a current estimation unit that estimates the first current value as an estimated current value based on the second current value and the third current value; and the first current sensor When the estimated current value is estimated by the first motor control unit that controls the first electric motor based on the estimated current value and the current estimating unit. The first motor control target value is kept constant. A motor control unit.

  According to the present invention, when the estimated current value is estimated by the current estimating unit, the control target value of the second electric motor is held constant. Thereby, since the second current value can be stabilized and the accuracy of the estimated current value can be increased, the first electric motor can be appropriately controlled even when the first current sensor fails.

It is the schematic which shows the control apparatus for vehicles which is one embodiment of this invention. It is a flowchart which shows an example of the execution procedure of an electric current estimation process. It is a flowchart which shows an example of the execution procedure of an engine starting process. It is a flowchart which shows an example of the execution procedure of an engine electric power generation process. It is a timing chart which shows the setting situation of the target motor current in engine starting processing and engine power generation processing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a vehicle control apparatus 10 according to an embodiment of the present invention. As shown in FIG. 1, the vehicle control device 10 includes a power unit 11 mounted on a hybrid vehicle. The power unit 11 includes an engine 12, a first motor generator MG1, and a second motor generator MG2 as power sources. The crankshaft 14 of the engine 12 is connected to the rotor 13r of the first motor generator MG1. Further, the drive wheel 18 is connected to the rotor 15r of the second motor generator MG2 via the drive wheel output shaft 16 and the differential mechanism 17. Thus, the engine 12 is connected to the first motor generator (first electric motor) MG1, and the drive wheels 18 are connected to the second motor generator (second electric motor) MG2.

  The stator 13s of the first motor generator MG1 is connected to the switching circuit unit 22 of the inverter 21 via the energization cable 20. Similarly, the stator 15 s of the second motor generator MG <b> 2 is connected to the switching circuit unit 24 of the inverter 21 via the energization cable 23. Further, the switching circuit units 22 and 24 and the battery (power storage device) 25 are connected to each other via an energization cable 26. Thus, the battery 25 is electrically connected to both the first motor generator MG1 and the second motor generator MG2 via the inverter 21. In addition, an air-conditioning compressor 27 and a converter 28, which are high-voltage electric devices, are connected to the energization cable 26 extending from the battery 25. The converter 28 has a function of stepping down battery power, and a low-voltage electric device 29 is connected to the converter 28.

  The first motor generator MG1 coupled to the engine 12 is a power generation motor that mainly functions as a generator. The first motor generator MG1 also functions as a starter motor that starts and rotates the engine 12 when the engine is started. The second motor generator MG2 coupled to the drive wheel 18 is a traveling motor that functions as a motor during acceleration and functions as a generator during deceleration. Thus, both motor generators MG1, MG2 can function as electric motors and can function as generators. In the illustrated example, the first motor generator MG1 and the second motor generator MG2 are mechanically separated from each other, but the present invention is not limited to this. For example, the first motor generator MG1 and the second motor generator MG2 may be mechanically connected via a power split mechanism including a planetary gear train and a clutch.

  The vehicle control device 10 includes a controller 30 that controls the engine 12, the first motor generator MG1, the second motor generator MG2, and the like. The controller 30 has an engine control unit 31, a first motor control unit 32, and a second motor control unit 33. The engine control unit 31 outputs a control signal to a throttle valve, an injector, an igniter, and the like (not shown) to control the engine torque and engine speed of the engine 12. The first motor control unit 32 outputs a control signal to the switching circuit unit 22 of the inverter 21 to control the motor torque and the motor rotation speed of the first motor generator MG1. The second motor control unit 33 outputs a control signal to the switching circuit unit 24 of the inverter 21 to control the motor torque and the motor rotation speed of the second motor generator MG2.

  The controller 30 includes a microcomputer configured with a CPU, a ROM, a RAM, and the like, a drive circuit unit that generates control currents for various actuators, and the like. Also connected to the controller 30 are a vehicle speed sensor 34 that detects the vehicle speed, which is the traveling speed of the vehicle, an accelerator sensor 35 that detects the operation status of the accelerator pedal, a brake sensor 36 that detects the operation status of the brake pedal, and the like. . Further, the controller 30 is connected to a first current sensor Se1 provided in the energization cable 20, a second current sensor Se2 provided in the energization cable 23, and a third current sensor Seb provided in the energization cable 26. The first current sensor Se1 detects an actual motor current (first current value) im1 that is an actual current of the first motor generator MG1, and the second current sensor Se2 is an actual motor that is an actual current of the second motor generator MG2. The current (second current value) im2 is detected. The third current sensor Seb detects a battery current (third current value) ib that is an actual current of the battery 25.

  As described above, various information indicating the driving operation of the driver, the traveling state of the vehicle, the operating state of the power unit 11, and the like are input to the controller 30 from various sensors. Controller 30 controls engine 12, first motor generator MG1, second motor generator MG2, and the like based on input information from various sensors. For example, the second motor control unit 33 that controls the second motor generator MG2 has a target motor current (control target value) that flows through the second motor generator MG2 based on the target motor torque and the target motor rotation speed of the second motor generator MG2. ) Set Tim2. That is, the target motor current Tim2, which is the current consumption of the second motor generator MG2, is set during acceleration running in which the second motor generator MG2 is powered. On the other hand, at the time of decelerating traveling for regenerating second motor generator MG2, target motor current Tim2 that is a generated current of second motor generator MG2 is set. Then, the second motor control unit 33 outputs a control signal to the switching circuit unit 24 of the inverter 21 so that the actual motor current im2 that is the actual current converges to the target motor current Tim2 that is the target value.

  Similarly, the first motor control unit 32 that controls the first motor generator MG1 sets the target motor current Tim1 that flows through the first motor generator MG1 based on the target motor torque and the target motor rotation speed of the first motor generator MG1. To do. That is, at the time of starting the engine in which the first motor generator MG1 is powered, the target motor current Tim1 that is the current consumption of the first motor generator MG1 is set. On the other hand, at the time of engine power generation in which the first motor generator MG1 generates electric power, a target motor current Tim1 that is a generated current of the first motor generator MG1 is set. Then, the first motor control unit 32 outputs a control signal to the switching circuit unit 22 of the inverter 21 so that the actual motor current im1 as the actual current converges to the target motor current Tim1 as the target value.

  Therefore, when a failure occurs in the first current sensor Se1 that detects the actual motor current im1, that is, when the controller 30 cannot grasp the actual motor current im1, it is difficult to control the first motor generator MG1. It was. As described above, when the first motor generator MG1 becomes inoperable, the motor traveling for driving only the second motor generator MG2 is executed from the viewpoint of ensuring the traveling performance of the hybrid vehicle. However, when the first motor generator MG1 becomes inoperable, the battery 25 cannot be charged by the first motor generator MG1, so that it is difficult to continue the motor running. For this reason, it is required to appropriately control the first motor generator MG1 even when the first current sensor Se1 fails.

[Current estimation processing]
Even when the first current sensor Se1 fails, in order to appropriately control the first motor generator MG1, the controller 30 is provided with a current estimating unit 40 that estimates the actual motor current im1. Hereinafter, the current estimation process executed by the current estimation unit 40 will be described. FIG. 2 is a flowchart illustrating an example of an execution procedure of the current estimation process. As shown in FIG. 2, in step S10, it is determined whether or not the first current sensor Se1 is out of order. In step S10, for example, when the sensor voltage output from the first current sensor Se1 indicates the ground voltage or the power supply voltage under the state where the first motor generator MG1 is rotating, It is determined that a failure has occurred in one current sensor Se1. If it is determined in step S10 that the first current sensor Se1 has failed, the process proceeds to step S11, the actual motor current im2 is read from the second current sensor Se2, and the process proceeds to step S12, where the third current sensor Battery current ib is read from Seb. Then, it progresses to step S13 and the electric current estimation part 40 calculates estimated motor current (estimated current value) im1 'which is the estimated actual motor current im1 based on the following formula | equation (1). As described above, the current estimation unit 40 calculates the estimated motor current im1 ′ based on the battery current ib and the actual motor current im2.
im1 ′ = | ib−im2 | (1)

  In step S13, the current estimation unit 40 calculates the difference between the battery current ib and the actual motor current im2 as the estimated motor current im1 '. However, the present invention is not limited to this. For example, not only the actual motor current im2 but also the current consumed by the converter 28, the air conditioner compressor 27, etc. may be subtracted from the battery current ib to improve the estimation accuracy of the estimated motor current im1 '. That is, the estimated motor current im1 'can be calculated with higher accuracy by subtracting the current consumption of the electrical device connected to the battery 25 from the battery current ib. For example, the battery current ib is read as a positive value when the battery is charged, and is read as a negative value when the battery is discharged. For example, the actual motor current im2 is read as a positive value when the second motor generator MG2 is regenerated, and is read as a negative value when the second motor generator MG2 is powered.

[Engine start processing]
Next, engine start processing executed by the controller 30 will be described. This engine start process is an engine start process that is executed under the condition where the first current sensor Se1 has failed, and is an engine start process that is executed using the estimated motor current im1 ′. Further, the engine start process is executed, for example, when the state of charge SOC of the battery 25 falls below a predetermined lower limit value, that is, when it is determined that power generation control using engine power is necessary. As shown in FIG. 1, the controller 30 is provided with an engine start determination unit 41 that determines a start state of the engine 12.

  FIG. 3 is a flowchart showing an example of an execution procedure of the engine start process. As shown in FIG. 3, in step S20, the second motor control unit 33 sets a reference target value T2 for the second motor generator MG2 based on the travel situation such as the accelerator opening and the vehicle speed. In the subsequent step S21, the target motor current Tim2, which is the target current value of the second motor generator MG2, is set by keeping the reference target value T2 constant. Then, the second motor control unit 33 controls the switching circuit unit 24 of the inverter 21 so that the actual motor current im2 is converged to the target motor current Tim2 held constant.

  Subsequently, in step S22, in order to start and rotate the engine 12 by the first motor generator MG1, the first motor control unit 32 sets a target motor current Tim1, which is a target current value for starting the engine. Then, the first motor control unit 32 controls the switching circuit unit 22 of the inverter 21 so that the estimated motor current im1 'converges to the target motor current Tim1. As described above, the actual motor current im2 of the second motor generator MG2 can be stabilized by keeping the target motor current Tim2 constant in step S21. Thereby, since the estimation accuracy of the estimated motor current im1 'can be improved, the first motor generator MG1 can be appropriately controlled even when the first current sensor Se1 is out of order.

  In subsequent step S23, the engine start determination unit 41 of the controller 30 determines whether or not the estimated motor current im1 'is below a predetermined start determination threshold value. If it is determined in step S23 that the estimated motor current im1 'exceeds the start determination threshold value, the process proceeds to step S24, and an engine power generation process for generating and driving the first motor generator MG1 using engine power is started. That is, the situation in which the estimated motor current im1 ′ exceeds the start determination threshold is a situation in which the estimated motor current im1 ′ that is the power generation current of the first motor generator MG1 increases. It is determined that the state has been shifted.

  On the other hand, if it is determined in step S23 that the estimated motor current im1 ′ is lower than the start determination threshold value, the engine 12 has not yet reached the complete explosion state. It is determined whether time has passed. If it is determined in step S25 that the specified time has not elapsed since the start of engine start, the process returns to step S23 to determine whether or not the estimated motor current im1 'is below a predetermined start determination threshold value. On the other hand, if it is determined in step S25 that the specified time has elapsed from the start of engine start, it is assumed that it is difficult to start the engine. Therefore, the process proceeds to step S26, and a fail safe corresponding to the engine start failure is detected. Control is executed.

  As shown in FIG. 3, in step S23, the starting state of the engine 12 is determined based on the estimated motor current im1 '. However, the present invention is not limited to this. For example, in step S23, the starting condition of the engine 12 may be determined based on the battery current ib. In this case, when the battery current ib as the battery discharge current decreases beyond a predetermined value or when the battery current ib as the battery charging current increases beyond the predetermined value, the power generation in the first motor generator MG1 Since an increase in current is captured, it is possible to determine whether the engine has been started.

[Engine power generation processing]
Next, engine power generation processing executed by the controller 30 will be described. The engine power generation process started in step S24 described above is an engine power generation process that is executed under a state where the first current sensor Se1 has failed, and is an engine power generation process that is executed using the estimated motor current im1 ′. is there.

  FIG. 4 is a flowchart showing an example of an execution procedure of the engine power generation process. As shown in FIG. 4, in step S30, the second motor control unit 33 sets the reference target value T2 of the second motor generator MG2 based on the traveling state such as the accelerator opening and the vehicle speed. In the subsequent step S31, the target motor current Tim2 of the second motor generator MG2 is set by keeping the reference target value T2 constant. Then, the second motor control unit 33 controls the switching circuit unit 24 of the inverter 21 so that the actual motor current im2 is converged to the target motor current Tim2 held constant.

  Subsequently, in step S32, the target motor current Tim1 of the first motor generator MG1 is set based on the battery state such as the state of charge SOC of the battery 25 and the charge / discharge balance. Then, the first motor control unit 32 controls the switching circuit unit 22 of the inverter 21 so that the estimated motor current im1 'converges to the target motor current Tim1. As described above, the actual motor current im2 of the second motor generator MG2 can be stabilized by keeping the target motor current Tim2 constant in step S31. Thereby, since the estimation accuracy of the estimated motor current im1 'can be improved, the first motor generator MG1 can be appropriately controlled even when the first current sensor Se1 is out of order.

[Timing chart]
Subsequently, a setting state of the target motor current Tim2 in the engine start process and the engine power generation process will be described. FIG. 5 is a timing chart showing a setting state of the target motor current Tim2 in the engine start process and the engine power generation process. In the timing chart of FIG. 5, after the first motor generator MG1 starts and rotates the engine 12 under the state where the first current sensor Se1 is out of order, the engine 12 that has been started is turned on by the first motor generator MG1. The situation in which the generator is driven is shown. In FIG. 5, time t1 indicates the timing for starting the engine, and time t2 indicates the timing for completing the engine start.

  As indicated by the symbol Xa in FIG. 5, in the engine starting process, even when the reference target value T2 changes according to the accelerator opening or the like, the target motor current Tim2 is held constant. Further, as indicated by the symbol Xb in FIG. 5, even in the case where the reference target value T2 changes in accordance with the accelerator opening or the like in the engine power generation process, the target motor current Tim2 is kept constant over a predetermined period. Is done. Thus, when estimating the estimated motor current im1 ', the actual motor current im2 of the second motor generator MG2 can be stabilized by keeping the target motor current Tim2 constant. Thereby, since the estimation accuracy of the estimated motor current im1 'can be improved, the first motor generator MG1 can be appropriately controlled even when the first current sensor Se1 is out of order.

  Further, although it depends on the state of charge SOC of the battery 25 and the charge / discharge balance, it is assumed that the engine power generation process is performed for a long time. For this reason, when the target motor current Tim2 is kept constant, there is a possibility that the reference target value T2 and the target motor current Tim2 greatly deviate. Therefore, as shown in FIG. 5, in the engine power generation process, the target motor current Tim2 is kept constant over a predetermined period P1, and then updated by making the target motor current Tim2 coincide with the reference target value T2. That is, in the engine power generation process, when the target motor current Tim2 is increased or decreased, step S1 for keeping the target motor current Tim2 constant and step S2 for updating the target motor current Tim2 are executed alternately and repeatedly. .

  As described above, in the engine power generation process, by changing the target motor current Tim2 stepwise, the estimation accuracy of the estimated motor current im1 ′ can be increased while suppressing a large difference between the reference target value T2 and the target motor current Tim2. Can be improved. The predetermined period P1 during which the target motor current Tim2 is kept constant is a period during which the estimated motor current im1 'can be estimated with high accuracy. In other words, the predetermined period P1 for keeping the target motor current Tim2 constant is a period for stabilizing the actual motor current im2 after the update of the target motor current Tim2.

  As shown in FIG. 5, in the engine power generation process, when the target motor current Tim2 is updated, the target motor current Tim2 is matched with the reference target value T2, but the present invention is not limited to this. For example, an upper limit value may be set for the increase / decrease amount when the target motor current Tim2 is updated. In the engine power generation process, the target motor current Tim2 is held constant over the predetermined period P1, but the predetermined period P1 for holding the target motor current Tim2 may be changed according to the situation. In the engine start process, the target motor current Tim2 is not changed because it is a short period. However, the present invention is not limited to this, and even if the target motor current Tim2 is changed stepwise in the engine start process. good.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the vehicle control device 10 according to one embodiment may be applied to a series-type hybrid vehicle or a series-parallel type hybrid vehicle. In the above description, the battery 25 is used as the power storage device. However, the present invention is not limited to this, and a capacitor may be used as the power storage device. In the illustrated example, a three-phase AC motor such as a synchronous motor or an induction motor is employed as the first motor generator MG1 and the second motor generator MG2. However, the present invention is not limited to this. The first current sensor Se1 and the second current sensor Se2 may be current sensors that detect all current values in the motor phases (U phase, V phase, W phase). May be a current sensor that detects a part of the current sensor.

DESCRIPTION OF SYMBOLS 10 Vehicle control apparatus 12 Engine 18 Drive wheel 25 Battery (electric storage device)
30 controller 31 engine control unit 32 first motor control unit 33 second motor control unit 40 current estimation unit 41 engine start determination unit MG1 first motor generator (first electric motor)
MG2 Second motor generator (second electric motor)
Se1 First current sensor Se2 Second current sensor Seb Third current sensor im1 Actual motor current (first current value)
im2 Actual motor current (second current value)
ib Battery current (third current value)
im1 'Estimated motor current (estimated current value)
Tim2 target motor current (control target value)
S1 step S2 step

Claims (6)

A first electric motor coupled to the engine;
A second electric motor coupled to the drive wheel;
An electricity storage device electrically connected to both the first electric motor and the second electric motor;
A first current sensor for detecting a first current value of the first electric motor;
A second current sensor for detecting a second current value of the second electric motor;
A third current sensor for detecting a third current value of the electricity storage device;
A current estimation unit configured to estimate the first current value as an estimated current value based on the second current value and the third current value;
A first motor controller that controls the first electric motor based on the estimated current value when the first current sensor is faulty;
A second motor control unit that holds a control target value of the second electric motor constant when the estimated current value is estimated by the current estimation unit;
A vehicle control device. The vehicle control device according to claim 1,
An engine start determination unit for determining a start state of the engine after the engine is started and rotated by the first electric motor;
The engine start determination unit is a vehicle control device that determines a start state of the engine based on the estimated current value or the third current value when the first current sensor is out of order. The vehicle control device according to claim 1 or 2,
The second motor control unit keeps the control target value of the second electric motor constant when the first electric motor starts and rotates the engine under a state where the first current sensor has failed. A control device for a vehicle to be held. The vehicle control device according to any one of claims 1 to 3,
The second motor control unit keeps the control target value of the second electric motor constant when the engine generates and drives the first electric motor under a state where the first current sensor is out of order. A control device for a vehicle to be held. In the vehicle control device according to any one of claims 1 to 4,
The second motor control unit holds the control target value of the second electric motor constant when increasing or decreasing the control target value of the second electric motor; and the control target value of the second electric motor. A vehicle control device that repeatedly and alternately executes the updating step. In the vehicle control device according to any one of claims 1 to 5,
The vehicle control apparatus, wherein the control target value of the second electric motor is set based on at least one of a target motor torque and a target motor rotation speed.

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