JP7379311B2 - Control device - Google Patents

Description

The present invention relates to a control device used in a hybrid vehicle (HV).

A series type hybrid vehicle is equipped with an engine, a generator motor (generator) that generates electricity using the engine's power, a drive motor that generates driving force for driving, and a battery that stores the electricity supplied to the drive motor. has been done.

When the output required for the drive motor is smaller than the output of the battery, the drive motor is driven by the electric power from the battery, and driving force is transmitted from the drive motor to the drive wheels. Thereby, the hybrid vehicle runs as an EV (Electric Vehicle). On the other hand, when the output required of the drive motor exceeds the output of the battery, the generator motor generates electricity using the power of the engine. Then, the drive motor is driven by the electric power from the generator motor, and driving force is transmitted from the drive motor to the drive wheels. As a result, the hybrid vehicle runs in HV mode.

Japanese Patent Application Publication No. 2016-88381

During HV driving, the engine speed and torque are controlled so that the engine operates at a high efficiency point where a good fuel efficiency is achieved relative to the output of the drive motor.

When the drive wheels slip (tire slip) during acceleration during HV driving, the torque of the drive motor is reduced (traction control) to suppress the slip. When the torque of the drive motor is reduced, the motor output, which is the product of the torque of the drive motor and the number of revolutions, is reduced, and accordingly, the number of revolutions of the engine fluctuates, giving the driver a sense of discomfort.

An object of the present invention is to provide a control device that is capable of suppressing fluctuations in the engine speed while generating electric power in accordance with the output of the motor using a generator when a drive wheel slip occurs during HV driving of a hybrid vehicle. The goal is to provide the following.

In order to achieve the above object, a control device according to one aspect of the present invention is equipped with a generator that converts engine power into electric power and a motor driven by the electric power, and the power generated by the motor is applied to drive wheels. This is a control device used in a hybrid vehicle that is driven by electric power, and includes an engine output adjustment means that adjusts the output of the engine so that the generator generates electricity according to the output of the motor, and a control device that adjusts the output of the engine so that the generator generates electricity according to the output of the motor. a motor torque reduction means for reducing the torque of the motor during a period from the occurrence of the slip until the grip of the drive wheels is restored when the slip of the drive wheels occurs during HV driving; The output adjustment means performs control such that the engine rotational speed changes slowly with respect to changes in the motor output when the motor torque is reduced by the motor torque reduction means.

According to this configuration, when slipping of the driving wheels occurs during HV driving of the hybrid vehicle, the torque of the motor is reduced within a period from the occurrence of the slip until the grip of the driving wheels is restored. Thereby, slip of the drive wheels can be suppressed, and the stability of the hybrid vehicle can be maintained.

As the torque of the motor decreases due to slipping of the drive wheels, the output of the engine is adjusted so that the generator generates electricity in accordance with the output of the motor. In adjusting the output of the engine, control is performed so that the engine rotational speed changes more slowly with respect to changes in the motor output. Therefore, while the generator generates electric power according to the output of the motor, fluctuations in the engine speed can be suppressed. As a result, it is possible to prevent the driver from feeling uncomfortable due to fluctuations in engine speed.

If the engine speed fluctuates in response to changes in motor output when the motor torque is reduced, the engine speed may drop significantly or the engine may It may stop. When the grip of the drive wheel tires is restored, the motor torque returns to the target torque corresponding to the acceleration request. However, if the engine speed has significantly decreased or the engine has stopped, the engine speed will be lower than the motor's target torque. It takes time for the rotation speed to rise to the level corresponding to the output, resulting in a delay in the motor output.

Preferably, the engine output adjustment means slows down the fluctuations in the engine rotational speed by controlling the engine torque to be reduced in accordance with the reduction in motor torque by the motor torque reduction means.

By reducing the engine torque, a reduction in the engine rotational speed is suppressed. This prevents the engine speed from dropping significantly or stopping the engine before the grip of the drive wheels is restored, and when the grip of the drive wheels is restored, the engine speed is The rotation speed can be immediately increased to a value corresponding to the target output of the motor, and delays in the output of the motor can be suppressed.

A control device according to another aspect of the present invention is provided for a hybrid vehicle that is equipped with a generator that converts engine power into electric power and a motor that is driven by the electric power, and that runs by transmitting the power generated by the motor to drive wheels. The control device used includes an engine output adjustment means that adjusts the output of the engine so that the generator generates electricity according to the output of the motor, and a control device that is driven during HV driving when the motor is driven by the electric power from the generator. When a wheel slip occurs, the engine output adjusting means includes a motor torque reducing means that reduces the torque of the motor within a period from the occurrence of the slip until the grip of the driving wheel is restored. When the torque of the motor is reduced by the means, a target value is set according to the vehicle speed of the hybrid vehicle, and control is performed to maintain the engine rotational speed at the target value.

According to this configuration, when slipping of the driving wheels occurs during HV driving of the hybrid vehicle, the torque of the motor is reduced within a period from the occurrence of the slip until the grip of the driving wheels is restored. Thereby, slip of the drive wheels can be suppressed, and the stability of the hybrid vehicle can be maintained.

As the torque of the motor decreases due to slipping of the drive wheels, the output of the engine is adjusted so that the generator generates electricity in accordance with the output of the motor. In adjusting the output of the engine, a target value is set according to the vehicle speed of the hybrid vehicle, and control is performed to maintain the engine speed at the target value. Therefore, while the generator generates electric power according to the output of the motor, fluctuations in the engine speed can be suppressed. As a result, it is possible to prevent the driver from feeling uncomfortable due to fluctuations in engine speed.

Furthermore, since the engine speed is maintained at a target value corresponding to the vehicle speed, the engine speed will not drop significantly or the engine will not stop until the grip of the drive wheels is restored. Therefore, when the grip of the tires of the drive wheels is restored, the engine speed can be immediately increased to the speed corresponding to the target output of the motor, and delays in the output of the motor can be suppressed.

A control device according to still another aspect of the present invention is a hybrid vehicle that is equipped with a generator that converts engine power into electric power and a motor that is driven by the electric power, and that runs by transmitting the power generated by the motor to drive wheels. This is a control device used for HV driving in which the motor is driven by electric power from the generator, and includes an engine output adjustment means for adjusting the output of the engine so that the generator generates electricity according to the output of the motor. When a drive wheel slips, the engine output adjusting means includes a motor torque reducing means for reducing the torque of the motor within a period from the occurrence of the slip until the grip of the drive wheel is restored, and the engine output adjusting means reduces the motor torque. Stopping the engine may be prohibited when the torque of the motor is being reduced by the reducing means.

According to this configuration, when slipping of the driving wheels occurs during HV driving of the hybrid vehicle, the torque of the motor is reduced within a period from the occurrence of the slip until the grip of the driving wheels is restored. Thereby, slip of the drive wheels can be suppressed, and the stability of the hybrid vehicle can be maintained.

As the torque of the motor decreases due to slipping of the drive wheels, the output of the engine is adjusted so that the generator generates electricity in accordance with the output of the motor. Then, while the output of the engine is being adjusted, stopping of the engine is prohibited and the engine continues to operate. This can prevent the driver from feeling uncomfortable due to repeated starting and stopping of the engine.

According to the present invention, when a drive wheel slip occurs during HV driving of a hybrid vehicle, it is possible to suppress fluctuations in engine rotational speed while generating electric power with a generator according to the output of the motor. , it is possible to prevent the driver from feeling uncomfortable due to fluctuations in engine speed.

1 is a block diagram showing the configuration of a hybrid vehicle equipped with a control device according to an embodiment of the present invention. It is a figure which shows an example of the time change of MG2 torque, MG2 rotation speed, MG2 output, and engine rotation speed.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Hybrid vehicle>
FIG. 1 is a block diagram showing the configuration of a hybrid vehicle 1. As shown in FIG.

The hybrid vehicle 1 is equipped with a series type hybrid system 2. The hybrid system 2 includes an engine 11, a generator motor (MG1) 12, a drive motor (MG2) 13, a battery 14, and a PCU (Power Control Unit) 15.

Engine 11 is, for example, a gasoline engine or a diesel engine.

The generator motor 12 is, for example, a permanent magnet synchronous motor. The rotating shaft of the generator motor 12 is mechanically connected to the crankshaft of the engine 11 via a gear (not shown). For example, an engine output gear is supported non-rotatably on the crankshaft of the engine 11, a motor gear is supported non-rotatably on the rotating shaft of the generator motor 12, and the engine output gear and the motor gear mesh with each other.

The drive motor 13 is, for example, a permanent magnet synchronous motor larger than the generator motor 12. A rotating shaft of the drive motor 13 is connected to a drive system 16 of the hybrid vehicle 1. The drive system 16 includes a differential gear, and the power of the drive motor 13 is transmitted to the differential gear, and from the differential gear is distributed and transmitted to drive wheels 17 consisting of left and right front wheels or rear wheels. As a result, the left and right drive wheels 17 rotate, and the hybrid vehicle 1 moves forward or backward.

The battery 14 is an assembled battery that is a combination of a plurality of secondary batteries (for example, lithium ion batteries). The battery 14 outputs DC power of approximately 200 to 350 V (volts), for example.

The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13, and includes a first inverter 21, a second inverter 22, and a converter 23.

When starting the engine 11, the DC power output from the battery 14 is boosted by the converter 23, the boosted DC power is converted to AC power by the first inverter 21, and the AC power is supplied to the generator motor 12. As a result, the generator motor 12 is powered, and the engine 11 is motored by the generator motor 12 . When the ignition plug of the engine 11 is sparked while the rotational speed of the crankshaft of the engine 11 is increased to the rotational speed necessary for starting by motoring, the engine 11 is started.

When the hybrid vehicle 1 is running, the drive motor 13 is operated in power running, and the drive motor 13 generates power.

When the output required from the drive motor 13 is smaller than the output from the battery 14, the hybrid vehicle 1 performs EV driving. That is, the engine 11 is stopped, the power generation motor 12 does not generate power, and power is supplied from the battery 14 to the drive motor 13, and the drive motor 13 is driven by the power.

On the other hand, when the output required from the drive motor 13 exceeds the output from the battery 14, the hybrid vehicle 1 runs in HV mode. That is, when the engine 11 is brought into operation and the generator motor 12 is operated to generate electricity, the power of the engine 11 is converted into alternating current power by the generator motor 12 . Then, the AC power from the generator motor 12 is converted to DC power by the first inverter 21, the DC power output from the first inverter 21 is converted to AC power by the second inverter 22, and the AC power is used to drive the drive motor. 13, the drive motor 13 is driven.

Furthermore, when the remaining capacity of the battery 14 falls below a predetermined level, the generator motor 12 is operated to generate electricity while the engine 11 is running, regardless of whether the drive motor 13 is driven or stopped. At this time, the AC power from the generator motor 12 is converted into DC power by the first inverter 21, the DC power output from the first inverter 21 is stepped down by the converter 23, and the stepped down DC power is supplied to the battery 14. As a result, the battery 14 is charged.

Further, the hybrid vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU includes a microcomputer (microcontroller unit), and the microcomputer includes, for example, a CPU, a nonvolatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). The plurality of ECUs are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol. Various sensors necessary for control are connected to each ECU, and detection signals from the connected sensors are input. In addition to the detection signals input from various sensors, each ECU receives information necessary for control from other ECUs.

FIG. 1 shows an ECU 31 that controls the hybrid system 2 among a plurality of ECUs.

<Traction control>
FIG. 2 is a diagram showing an example of temporal changes in MG2 torque, MG2 rotation speed, MG2 output, and engine rotation speed.

In the hybrid vehicle 1, during HV driving, the generator motor 12 generates electricity according to the output of the drive motor 13, and the engine 11 is activated at a high efficiency point where a good fuel efficiency rate is achieved with respect to the output of the drive motor 13. The ECU 31 controls the rotation speed and torque of the engine 11 so that the engine 11 operates.

When the drive wheels 17 slip during acceleration during HV driving (time T1), traction control is activated to suppress the slip, and the MG2 torque, which is the torque of the drive motor 13, reaches the target torque of the drive motor 13. (time T2).

The target torque of the drive motor 13 is set by the ECU 31 according to the accelerator opening degree. The accelerator opening degree is the ratio of the amount of operation by the driver to the maximum amount of operation of the accelerator pedal. For example, an accelerator sensor that outputs a detection signal according to the operation amount of the accelerator pedal is connected to the ECU 31, and the accelerator opening degree is calculated by the ECU 31 from the detection signal of the accelerator sensor.

When the drive wheel 17 slips, the MG2 rotation speed, which is the rotation speed of the drive motor 13 mechanically connected to the drive wheel 17, increases, and the MG2 rotation speed changes depending on the MG2 rotation speed and the vehicle body speed of the hybrid vehicle 1. A discrepancy occurs. Therefore, if a deviation of a certain amount or more occurs between the actual MG2 rotational speed and the MG2 rotational speed estimated from the vehicle speed, it can be determined that slipping of the drive wheels 17 has occurred.

Thereafter, when the discrepancy between the actual MG2 rotation speed and the MG2 rotation speed estimated from the vehicle speed has almost disappeared, and the ECU 31 determines that the grip of the drive wheels 17 has been restored, the operation of the traction control is terminated. The reduction in MG2 torque is canceled (time T3). After the reduction in MG2 torque is canceled, the MG2 torque is quickly increased to the target torque according to the accelerator opening degree. As a result, the MG2 output increases immediately, and the hybrid vehicle 1 accelerates at an acceleration corresponding to the accelerator opening.

The output of the engine 11 is adjusted so that the power generation motor 12 generates power according to the output of the drive motor 13 even when the drive wheels 17 are slipping, that is, while the traction control is in operation. In the output adjustment of the engine 11 during this slip, the torque of the engine 11 is controlled, and the rotational speed of the engine 11 (engine rotational speed) is maintained at a target value according to the vehicle speed of the hybrid vehicle 1.

<Effect>
As described above, when the drive wheels 17 slip during acceleration during HV driving of the hybrid vehicle 1 (time T1), during the period T2-T3 from the occurrence of the slip until the grip of the drive wheels 17 is restored, The MG2 torque, which is the torque of the drive motor 13, is reduced relative to the target torque. Thereby, slip of the drive wheels 17 can be suppressed, and the stability of the hybrid vehicle 1 can be maintained.

As the MG2 torque decreases due to the slip of the drive wheels 17, the output of the engine 11 is adjusted so that the power generation motor 12 generates power according to the MG2 output that is the output of the drive motor 13. In adjusting the output of the engine 11, a target value is set according to the vehicle speed of the hybrid vehicle 1, and control is performed to maintain the rotation speed of the engine 11 at the target value. Therefore, it is possible to suppress fluctuations in the rotational speed of the engine 11 while generating electric power with the power generation motor 12 according to the output of the MG2. As a result, it is possible to prevent the driver from feeling uncomfortable due to fluctuations in the rotational speed of the engine 11.

As shown by the two-dot chain line in FIG. 2, when the MG2 torque is reduced and the rotational speed of the engine 11 fluctuates in response to fluctuations in the MG2 output, by the time the grip of the drive wheels 17 is restored, The rotational speed of the engine 11 may drop significantly or the engine 11 may stop. When the grip of the tires of the driving wheels 17 is restored, the MG2 torque is returned to the target torque according to the accelerator opening. It takes time for the rotation speed of the drive motor 13 to rise to the rotation speed corresponding to the target output of the drive motor 13, and as shown by the two-dot chain line in FIG. There will be a delay in output.

During the reduction of MG2 torque, under control in which the rotation speed of the engine 11 is maintained at a target value according to the vehicle speed, the rotation speed of the engine 11 may decrease significantly or never stops. Therefore, when the grip of the tire of the drive wheel 17 is restored, the rotation speed of the engine 11 can be immediately increased to the rotation speed corresponding to the target output of the drive motor 13, and it is possible to suppress a delay in the MG2 output. .

<Modified example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, in the above-described embodiment, the rotation speed of the engine 11 is maintained at a target value depending on the vehicle speed of the hybrid vehicle 1 while the MG2 torque is being reduced to suppress the slip of the drive wheels 17. The value is not limited to a value depending on the vehicle speed, but may be a constant value set regardless of the vehicle speed. In addition, instead of the rotation speed of the engine 11 being fixed at a target value, a lower limit value of the rotation speed of the engine 11 is set, and the rotation speed of the engine 11 is not set below the lower limit value. The torque of the engine 11 may be controlled such that the output of the engine 11 is adjusted according to the MG2 output that is the output of the drive motor 13.

In other words, it is only necessary to slow down fluctuations in the rotational speed of the engine 11 by controlling the torque of the engine 11 to be reduced in accordance with the reduction of the MG2 torque, which is the torque of the drive motor 13, and to keep the rotational speed of the engine 11 constant. By fixing the rotation speed of the engine 11, fluctuations in the rotation speed of the engine 11 may be slowed down, or by adjusting the torque and rotation speed of the engine 11 within a range where the rotation speed of the engine 11 does not fall below the lower limit value. The rotational speed may vary slowly.

In the control that fixes the rotation speed of the engine 11 constant and the control that sets the lower limit value of the rotation speed of the engine 11, stopping of the engine 11 is substantially prohibited, so starting and stopping of the engine 11 are repeated. This also has the effect of preventing the driver from feeling uncomfortable.

Further, in the above-described embodiment, an example has been taken up in which the MG2 torque, which is the torque of the drive motor 13, is reduced with respect to the target torque when the drive wheels 17 slip during acceleration during HV driving. Even during steady driving when the accelerator opening is constant, slipping of the driving wheels 17 may occur, for example, when the driving wheels 17 approach a road surface with a low road surface μ. The above-described control may be performed by reducing the MG2 torque with respect to the target torque.

In addition, various design changes can be made to the above-described configuration within the scope of the claims.

1: Hybrid vehicle 11: Engine 12: Generator motor (generator)
13: Drive motor (motor)
17: Drive wheel 31: ECU (control device, engine output adjustment means, motor torque reduction means)

Claims (1)

A control device for use in a hybrid vehicle equipped with a generator that converts engine power into electric power and a motor driven by the electric power, and in which the power generated by the motor is transmitted to drive wheels and runs,
engine output adjustment means for adjusting the output of the engine so that the generator generates electricity according to the output of the motor;
If the drive wheel slips during HV driving in which the motor is driven by electric power from the generator, the motor may slip during the period from the occurrence of the slip until the drive wheel regains its grip. a motor torque reduction means for reducing torque;
The engine output adjusting means prohibits stopping of the engine when the motor torque reducing means reduces the torque of the motor , sets a lower limit value of the number of revolutions of the engine, and reduces the number of revolutions of the engine. A control device that fixes the rotational speed of the engine to a constant value within a range where the rotational speed of the engine does not fall below the lower limit value .

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