Hybrid vehicle control device

Abstract

To provide a control device for a hybrid vehicle, capable of suppressing the fluctuation of a motoring revolution speed.SOLUTION: A motoring allowable revolution speed corresponding to the vehicle speed of a hybrid vehicle is set (S3). The motoring of an engine is performed at the motoring allowable revolution speed (S4). As a result, even when an acceleration request by accelerator operation or road surface resistance is changed, if the motoring allowable revolution speed is not changed, in other words, if the vehicle speed is not changed, a revolution speed in the motoring of the engine (a motoring revolution speed) does not fluctuate. In addition, the upper limit of regenerative electric power obtained by the regenerative operation of a drive motor is set to electric power consumption in the motoring (S5).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] For example, a series type hybrid system includes an engine, a generator motor that generates electricity using power from the engine, a drive motor that generates driving force for traveling, and a battery that stores the electricity supplied to the drive motor.

[0003] In a vehicle equipped with such a hybrid system, when the output required of the drive motor is smaller than the output of the battery, the drive motor is driven by electric power from the battery, and the drive force is transmitted from the drive motor to the drive wheels. On the other hand, when the output required of the drive motor exceeds the output of the battery, the engine power is converted to electric power by the generator motor, the drive motor is driven by the electric power from the generator motor, and the drive force is transmitted from the drive motor to the drive wheels. Furthermore, when the vehicle is decelerating, the drive motor is operated in regenerative mode, and the power transmitted from the drive wheels to the drive motor is converted to electric power. At this time, the drive motor becomes a resistance to the driving system, and this resistance acts as a braking force (regenerative braking force) that brakes the vehicle. The electric power generated by the drive motor is stored in the battery and used to drive the drive motor. This improves the fuel efficiency of the vehicle.

[0004] Lithium-ion batteries are used for the batteries. Lithium-ion batteries deteriorate faster due to lithium precipitation when charged and discharged in low-temperature environments, so charge and discharge power (charging power and discharging power) is generally limited in low-temperature environments. When the battery's charging and discharging power is limited, the power balance is balanced by driving a generator motor with power generated by regenerative operation of the drive motor and motoring the engine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-47820 A Summary of the Invention [Problem to be solved by the invention]

[0006] In this case, it is necessary to keep the difference between the regenerative power by the drive motor and the power consumption (discharge power) by the generator motor within a limit value. In addition, in motoring, the generator motor consumes power by rotating the engine with a torque equivalent to the friction torque of the engine, so when the discharge power is relatively large, the engine needs to be rotated at a high speed, and when the discharge power is relatively small, the engine needs to be rotated at a low speed. Therefore, in a region where the regenerative power by the drive motor changes depending on the accelerator operation, the rotation speed due to motoring of the engine (motoring rotation speed) varies depending on the accelerator operation, which may cause a sense of discomfort to the user.

[0007] An object of the present invention is to provide a control device for a hybrid vehicle that can suppress fluctuations in motoring rotation speed. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the control device for a hybrid vehicle of the present invention is a control device used in a hybrid vehicle equipped with an engine, a generator motor that generates electricity using power from the engine, a drive motor that generates power for driving, and a battery that stores electricity, and includes a generator motor control means that sets a permissible motoring speed according to the vehicle speed of the hybrid vehicle and motors the engine at the set permissible motoring speed by powering the generator motor, and a drive motor control means that operates the drive motor in a regenerative manner, with the power consumption during motoring by the generator motor control means as an upper limit on the regenerative power obtainable by regenerative operation of the drive motor.

[0009] According to this configuration, the permissible motoring speed is set according to the vehicle speed of the hybrid vehicle, and the engine is motored at the permissible motoring speed. Therefore, even if the acceleration request due to accelerator operation or road resistance changes, if there is no change in the permissible motoring speed, that is, if there is no change in the vehicle speed, the motoring speed of the engine will not fluctuate, so it is possible to suppress the discomfort felt by the user due to fluctuations in the motoring speed.

[0010] In addition, by setting the upper limit of the regenerative power obtained by the regenerative operation of the drive motor as the power consumption during motoring, the regenerative power can be consumed without waste during motoring. As a result, when the battery charge / discharge power is limited due to a low temperature environment, charging / discharging of the battery can be prevented, and the battery can be protected from deterioration due to charging / discharging.

[0011] Furthermore, when the acceleration request is small and the regenerative power from the regenerative operation of the drive motor is small, the motoring consumes more power than the regenerative power, reducing the remaining charge of the battery. If motoring is performed during engine warm-up to increase the engine water temperature, the engine combustion is stopped by cutting the fuel, so it takes time to increase the engine water temperature and the period until the heater and defroster function is extended. As the remaining charge of the battery decreases, the battery is less likely to become fully charged, so motoring can be suppressed during engine warm-up. As a result, the engine water temperature can be quickly increased when the engine is warmed up.

[0012] The motoring permissible rotation speed may be set based on the relationship between the running sound, which increases or decreases according to the vehicle speed of the hybrid vehicle, and the noise generated from the engine due to motoring.

[0013] For example, the motoring permissible revolution speed may be set so that engine noise caused by motoring is equal to or lower than the running noise of the hybrid vehicle. This masks the engine noise with the running noise, thereby preventing the engine noise from causing discomfort to the user.

[0014] The drive motor control means sets a target torque according to an acceleration request, and when the target torque is a powering torque, operates the drive motor in powering mode so that a motor torque of the target torque is generated, and the generator motor control means continues motoring until the target torque of the drive motor is set to powering torque or the amount of discharge from the battery exceeds the allowable discharge amount, and the control device may further include transition means for transitioning from engine motoring by the generator motor to engine firing while maintaining the engine speed at the allowable motoring speed when the target torque of the drive motor is set to powering torque or the amount of discharge from the battery exceeds the allowable discharge amount.

[0015] According to this configuration, when the target torque of the drive motor is set to a powering torque during engine motoring, or when the amount of discharge from the battery exceeds the allowable amount of discharge, the engine operation state is shifted from motoring to firing while the engine speed is maintained at the allowable motoring speed. This makes it possible to suppress fluctuations in the engine speed during the shift, and to suppress the discomfort felt by the user due to fluctuations in the engine speed. Effect of the Invention

[0016] According to the present invention, it is possible to suppress fluctuations in the motoring speed of the engine, and to suppress the sense of discomfort felt by the user due to fluctuations in the motoring speed. [Brief description of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a configuration of a hybrid vehicle to which a control device according to an embodiment of the present invention is applied; [Diagram 2] 10 is a flowchart showing a flow of power balance control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0019] <Hybrid vehicle> FIG. 1 is a block diagram showing the configuration of a hybrid vehicle 1. As shown in FIG.

[0020] The hybrid vehicle 1 is equipped with a series 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.

[0021] The engine 11 is, for example, a gasoline engine.

[0022] 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 on the crankshaft of the engine 11 so as not to rotate relative thereto, and a motor gear is supported on the rotating shaft of the generator motor 12 so as not to rotate relative thereto, and the engine output gear and the motor gear are meshed with each other.

[0023] The drive motor 13 is, for example, a permanent magnet synchronous motor that is 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 distributed and transmitted from the differential gear to drive wheels 17 consisting of left and right front wheels or rear wheels. This causes the left and right drive wheels 17 to rotate, and the hybrid vehicle 1 moves forward or backward.

[0024] The battery 14 is an assembled battery made up of a combination of a plurality of secondary batteries. The secondary batteries are, for example, lithium ion batteries. The battery 14 outputs DC power of, for example, about 200 to 350 V (volts).

[0025] 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 .

[0026] 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. This causes the generator motor 12 to perform power running, and the engine 11 is motored (cranked) by the generator motor 12. When the rotation speed of the crankshaft of the engine 11 has increased to a rotation speed required for starting due to motoring, the ignition plug of the engine 11 is sparked, and the engine 11 starts.

[0027] When the hybrid vehicle 1 is traveling, the drive motor 13 is operated in a power running mode, and generates power.

[0028] When the output required for the drive motor 13 is smaller than the output of the battery 14, the hybrid vehicle 1 runs in EV mode. That is, the engine 11 is stopped, power generation by the generator motor 12 is not performed, and power is supplied from the battery 14 to the drive motor 13, which drives the drive motor 13.

[0029] On the other hand, when the output required for the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle 1 runs as an HV. That is, the engine 11 is operated and the generator motor 12 is operated to generate electricity (regenerative operation), so that the power of the engine 11 is converted to AC 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, and the DC power output from the first inverter 21 is converted to AC power by the second inverter 22, and the AC power is supplied to the drive motor 13, thereby driving the drive motor 13.

[0030] Furthermore, when the remaining capacity of the battery 14 falls below a predetermined level, the generator motor 12 operates to generate electricity while the engine 11 is running, regardless of whether the drive motor 13 is driven or stopped. At this time, AC power from the generator motor 12 is converted to DC power by the first inverter 21, and 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, thereby charging the battery 14.

[0031] When the hybrid vehicle 1 decelerates, the drive motor 13 is operated in a regenerative manner, and the power transmitted from the drive wheels 17 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 acts as a resistance in the running drive system, and the resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 1. At this time, in the PCU 15, the AC power supplied from the drive motor 13 to the second inverter 22 is converted into DC power by the second inverter 22, and the DC power output from the second inverter 22 is stepped down by the converter 23. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

[0032] A hybrid vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU has a microcontroller unit (microcomputer), and the microcomputer has built-in, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The plurality of ECUs are connected to enable two-way communication by a controller area network (CAN) communication protocol. Each ECU is connected to various sensors required for control, and receives detection signals from the connected sensors. In addition to the detection signals input from the various sensors, each ECU also receives information required for control from other ECUs.

[0033] 1 shows an ECU 31, which is one of the multiple ECUs and controls the hybrid system 2. An accelerator sensor 32 and a vehicle speed sensor 33 are connected to the ECU 31. The accelerator sensor 32 outputs a detection signal corresponding to the amount of operation of an accelerator pedal operated by a driver (operator). The vehicle speed sensor 33 outputs a pulse signal as a detection signal synchronized with the rotation of a rotating body that rotates as the hybrid vehicle 1 travels. From the detection signal of the accelerator sensor 32, the ECU 31 determines the accelerator opening, which is the ratio of the current operation amount to the maximum operation amount of the accelerator pedal. Furthermore, the ECU 31 determines the frequency of the detection signal (pulse signal) from the detection signal of the vehicle speed sensor 33, and converts the frequency into vehicle speed.

[0034] <Power balance control> FIG. 2 is a flowchart showing the flow of power balance control.

[0035] In the hybrid vehicle 1, for example, in response to the ignition switch being turned on, the ECU 31 performs power balance control.

[0036] In the power balance control, the ECU 31 determines whether or not the environment is a low temperature environment (step S1). A low temperature environment here refers to an environment in which the lithium ion battery used in the battery 14 may deteriorate due to lithium deposition when the battery 14 is charged or discharged. If the environment is a low temperature environment, the charge and discharge power (charging power and discharging power) of the battery 14 is limited to a certain amount or less. If the environment is not a low temperature environment (NO in step S1), the charge and discharge power of the battery 14 is not limited, and the power balance control is terminated.

[0037] In a low temperature environment (YES in step S1) and in a state in which the charging and discharging power of the battery 14 is limited to a certain level or less, the ECU 31 sets the charging power of the battery 14 to 0 kW (step S2).

[0038] Furthermore, the ECU 31 sets a permissible motoring speed according to the vehicle speed of the hybrid vehicle 1 (step S3). The permissible motoring speed is a permissible value of the rotation speed of motoring the engine 11 by the generator motor 12. For example, the vehicle speed from 0 km / h to a predetermined maximum vehicle speed (e.g., 180 km / h) is divided into a plurality of vehicle speed ranges, and the permissible motoring speed is predetermined for each vehicle speed range so that the noise of the engine 11 due to motoring is equal to or lower than the running sound of the hybrid vehicle 1.

[0039] After the permissible motoring speed corresponding to the vehicle speed is set, a command based on the permissible motoring speed is transmitted from the ECU 31 to the PCU 15. Then, in accordance with the command, a microcomputer built into the PCU 15 controls the first inverter 21 and the converter 23, so that the generator motor 12 is powered by electric power from the battery 14, and the generator motor 12 motors the engine 11 at the permissible motoring speed (step S4).

[0040] Meanwhile, the ECU 31 calculates the power consumption caused by motoring the engine 11 at the motoring permissible rotation speed. Then, the calculated power consumption is set to the maximum regenerative power, which is the upper limit of the regenerative power obtained by the regenerative operation of the drive motor 13 (step S5).

[0041] Further, the ECU 31 sets a target torque, which is a target of the motor torque of the drive motor 13. The target torque of the drive motor 13 is set by the ECU 31 according to the accelerator opening. For example, a map that defines the relationship between the accelerator opening and the target torque is stored in the non-volatile memory of the ECU 31, and the target torque of the drive motor 13 is set according to the map so that in a range where the accelerator opening is larger than the first opening, the powering torque increases as the accelerator opening increases, and in a range where the accelerator opening is smaller than the second opening, the regenerative torque increases as the accelerator opening decreases. The first opening and the second opening may be different values ​​or may be the same value. When the first opening and the second opening are different values, the target torque is set to 0 when the first opening is larger than the second opening and the accelerator opening is in a range between the first opening and the second opening. When the first opening degree and the second opening degree are the same value, the target torque is set to 0 for that value of the accelerator opening degree.

[0042] If the target torque of the drive motor 13 is not a regenerative torque, that is, if the target torque is 0 or a powering torque (positive torque), the target torque is set as a command torque, and the command torque is transmitted from the ECU 31 to the PCU 15 (step S6). If the target torque of the drive motor 13 is a regenerative torque (negative torque), a command torque is set whose absolute value is a negative torque equal to or less than the target torque so that the regenerative power obtained by the regenerative operation of the drive motor 13 does not exceed the maximum regenerative power, and the command torque is transmitted from the ECU 31 to the PCU 15 (step S6).

[0043] When the target torque of the drive motor 13 is a regenerative torque, a microcomputer built into the PCU 15 controls the second inverter 22 based on the command torque, and regenerative power equal to or less than the maximum regenerative power is extracted from the second inverter 22. This regenerative power is supplied to the generator motor 12 via the first inverter 21. Since the regenerative power is equal to or less than the maximum regenerative power, none of it is left over and is consumed by the generator motor 12 for motoring the engine 11.

[0044] Thereafter, the ECU 31 determines whether the command torque is a powering torque (step S7). If the command torque is not a powering torque (NO in step S7), it determines whether the amount of discharge from the battery 14 after motoring has started has exceeded an allowable discharge amount (step S8). The allowable discharge amount is set, for example, to the difference between the remaining charge of the battery 14 at the start of motoring and the remaining charge that is the lower limit of the usage range of the battery 14.

[0045] Motoring of the engine 11 continues at the motoring permissible speed corresponding to the vehicle speed (steps S3 to S8) until the target torque of the drive motor 13 is set to the powering torque or the amount of discharge from the battery 14 exceeds the permissible discharge amount (YES in step S7). Then, when the target torque of the drive motor 13 is set to the powering torque (YES in step S7) or the amount of discharge from the battery 14 exceeds the permissible discharge amount (YES in step S8), the ECU 31 injects fuel from the injector and sparks the ignition plug while maintaining the motoring speed of the engine 11 by the generator motor 12 at the permissible motoring speed, and the operating state of the engine 11 transitions from motoring to firing (step S9), and the power balance control is terminated. After the transition, the target torque of the generator motor 12 is set to a low regenerative torque (negative torque) while the engine 11 remains at the same speed as in the motoring state, and firing operation of the engine 11 is performed.

[0046] <Action and effect> As described above, the permissible motoring rotation speed is set according to the vehicle speed of the hybrid vehicle 1, and the engine 11 is motored at the permissible motoring rotation speed. Therefore, even if the acceleration request due to accelerator operation or the road surface resistance changes, if there is no change in the permissible motoring rotation speed, that is, if there is no change in the vehicle speed, the rotation speed due to motoring of the engine 11 (motoring rotation speed) does not vary, so it is possible to suppress the user from feeling uncomfortable due to fluctuations in the motoring rotation speed.

[0047] In addition, the upper limit of the regenerative power obtained by the regenerative operation of the drive motor 13 is set as the power consumption during motoring, so that the regenerative power can be consumed without waste during motoring. As a result, when the charging / discharging power of the battery 14 is limited due to a low temperature environment or the like, charging / discharging of the battery 14 can be prevented, and the battery 14 can be protected from deterioration due to charging / discharging.

[0048] Furthermore, when the acceleration request is small and the regenerative power from the regenerative operation of the drive motor 13 is small, the motoring consumes more power than the regenerative power, and the remaining charge of the battery 14 decreases. If motoring is performed while the engine 11 is warming up to raise the engine water temperature, the combustion in the engine 11 is stopped by cutting the fuel, so it takes time to raise the engine water temperature and the period until the heater and defroster function is extended. As the remaining charge of the battery 14 decreases, the battery 14 is less likely to be fully charged, so motoring can be suppressed while the engine 11 is warming up. As a result, the engine water temperature can be raised quickly when the engine 11 is warming up.

[0049] The motoring permissible rotation speed is set based on the relationship between the running sound, which increases and decreases according to the vehicle speed of the hybrid vehicle 1, and the noise generated by the engine 11 due to motoring. Specifically, it is preferable to set the motoring permissible rotation speed so that the noise of the engine 11 due to motoring is equal to or lower than the running sound of the hybrid vehicle 1. This masks the noise of the engine 11 with the running sound, thereby preventing the noise of the engine 11 from causing discomfort to the user.

[0050] According to this configuration, when the target torque of the drive motor 13 is set to a powering torque during motoring of the engine 11, or when the amount of discharge from the battery 14 exceeds the allowable amount of discharge, the operating state of the engine 11 is shifted from motoring to firing while the rotation speed of the engine 11 is maintained at the allowable motoring rotation speed. This makes it possible to suppress fluctuations in the rotation speed of the engine 11 during the transition, and to suppress discomfort felt by the user due to fluctuations in the rotation speed of the engine 11.

[0051] <Modification> Although the embodiment of the present invention has been described above, the present invention can be embodied in other forms.

[0052] For example, in the above embodiment, when the target torque of the drive motor 13 is set to powering torque or when the amount of discharge from the battery 14 exceeds the allowable discharge amount, the operating state of the engine 11 is shifted from motoring to firing, but this is not limited thereto. When the target torque of the drive motor 13 is set to powering torque or when the amount of discharge from the battery 14 exceeds the allowable discharge amount, the generator motor 12 is stopped and the motoring of the engine 11 is terminated, and thereafter, when power generation by the generator motor 12 becomes necessary, the engine 11 may be operated in firing.

[0053] In addition, various design modifications can be made to the above-described configuration within the scope of the claims. [Explanation of symbols]

[0054] 1: Hybrid vehicle 11: Engine 12: Generator motor 13: Drive motor 14: Battery 15: PCU (control device, power generation motor control means, drive motor control means) 31: ECU (control device, generator motor control means, drive motor control means, transition means)

Claims

1. A control device for use in a hybrid vehicle equipped with an engine, a power generating motor that generates electricity using power from the engine, a drive motor that generates power for traveling, and a battery that stores the electricity, determining whether the battery is in a low-temperature environment in which the charge / discharge power amount of the battery is limited to a certain level or less; When it is determined that the low temperature environment is present, the charge / discharge power amount of the battery is limited to or below the certain level; In the low temperature environment, the charge / discharge power amount of the battery is limited to the certain amount or less. setting a motoring permissible rotation speed according to a vehicle speed of the hybrid vehicle, and motoring the engine at the set motoring permissible rotation speed by powering the generator motor; A control device that performs regenerative operation of the drive motor by setting the power consumption during motoring as an upper limit of regenerative power that can be obtained by the regenerative operation of the drive motor.

2. setting a target torque according to an acceleration request, and when the target torque is a powering torque, powering the drive motor so as to generate a motor torque of the target torque; motoring is continued until the target torque of the drive motor is set to a powering torque or the amount of discharge from the battery exceeds an allowable amount of discharge; 2. The control device according to claim 1, wherein when the target torque of the drive motor is set to a powering torque or when the amount of discharge from the battery exceeds the allowable discharge amount, a transition is made from motoring of the engine by the generator motor to firing of the engine while maintaining the engine speed at the allowable motoring speed.

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