WO2012111068A1

WO2012111068A1 - Vehicle, and vehicle control method

Info

Publication number: WO2012111068A1
Application number: PCT/JP2011/053009
Authority: WO
Inventors: 啓介森崎
Original assignee: トヨタ自動車株式会社
Priority date: 2011-02-14
Filing date: 2011-02-14
Publication date: 2012-08-23

Abstract

A hybrid car is equipped with an engine and a motor generator connected to car wheels. When the motor generator generates electricity regeneratively during the deceleration of the car, the driving of the engine is restricted. After the completion of the regenerative generation of electricity by the motor generator, the driving of the engine is still restricted.

Description

Vehicle and vehicle control method

The present invention relates to a vehicle and a vehicle control method, and more particularly to a technique for restricting engine operation when regenerative power generation is performed by an electric motor.

A hybrid vehicle equipped with an electric motor as a drive source in addition to the engine is known. The electric motor has a function as a generator in addition to a function as a drive source. Therefore, when the hybrid vehicle is braked, the electric motor can generate regenerative power. The regenerated power is stored in a power storage device such as a battery and a capacitor. The electric power stored in the power storage device is used for driving an electric motor, for example.

Some hybrid vehicles have a generator driven by an engine separately from an electric motor as a drive source. In such a hybrid vehicle, there is a problem that when the generator generates power simultaneously with the regenerative power generation by the electric motor, more power than necessary can be temporarily supplied to the battery.

In response to such a problem, Japanese Patent Application Laid-Open No. 7-279702 (Patent Document 1) discloses, in claim 13 and the like, that the engine is set in an idle state during regenerative braking (regenerative power generation) by an electric motor to limit power generation. To do.

JP 7-279702 A

However, if the output of the engine is reduced during regenerative power generation by the electric motor, the output of the engine can be increased after the regenerative power generation is completed. Therefore, when the vehicle speed decreases to a speed at which regenerative power generation cannot be performed, the sound emitted from the engine during deceleration can increase. Therefore, the driver may be misunderstood that the vehicle changes from deceleration to acceleration.

An object of the present invention is to prevent the engine output from increasing during deceleration.

In one embodiment, the vehicle includes an engine, an electric motor coupled to the wheels, and when the electric motor regeneratively generates power while the vehicle is decelerating, the operation of the engine is limited, and after the regenerative power generation by the electric motor ends, the engine And a control unit that continues to limit the operation of the system.

In another embodiment, a method for controlling a vehicle provided with an engine and an electric motor coupled to a wheel includes a step of limiting the operation of the engine when the electric motor regenerates power during deceleration of the vehicle, and the electric motor. And after the regenerative power generation by is completed, the step of continuing to limit the operation of the engine.

Even if regenerative power generation by the electric motor ends during deceleration, engine operation continues to be restricted. This limits the increase in engine output during deceleration.

1 is a schematic configuration diagram of a vehicle. It is a figure which shows the alignment chart of a power split device. It is a figure which shows the electric system of a vehicle. It is a figure which shows the period which an engine drives, and the period which stops. It is a timing chart which shows the driving | running state of the vehicle at the time of regenerative braking. It is a timing chart which shows the driving | running state of a vehicle when decelerating without generating regenerative power. It is a flowchart which shows the process which ECU performs.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

Referring to FIG. 1, engine 100, first motor generator 110, second motor generator 120, power split mechanism 130, reduction gear 140, and battery 150 are mounted on the vehicle. In the following description, a hybrid vehicle not having a charging function from an external power source will be described as an example, but a plug-in hybrid vehicle having a charging function from an external power source may be used.

Engine 100, first motor generator 110, second motor generator 120, and battery 150 are controlled by an ECU (Electronic Control Unit) 170. ECU 170 may be divided into a plurality of ECUs.

This vehicle travels by driving force from at least one of engine 100 and second motor generator 120. That is, either one or both of engine 100 and second motor generator 120 is automatically selected as a drive source according to the operating state.

For example, engine 100 and second motor generator 120 are controlled in accordance with the result of the driver operating accelerator pedal 172 and brake pedal 174. The operation amount (accelerator opening) of the accelerator pedal 172 is detected by an accelerator opening sensor (not shown). The operation amount of the brake pedal 174 is detected by a stroke sensor (not shown).

When the accelerator opening is small or the vehicle speed is low, the vehicle travels using only the second motor generator 120 as a drive source. In this case, engine 100 is stopped. However, the engine 100 may be driven for power generation or the like.

Also, when the accelerator opening is large, the vehicle speed is high, or the remaining capacity (SOC: State Of Charge) of the battery 150 is small, the engine 100 is driven. In this case, the vehicle travels using only engine 100 or both engine 100 and second motor generator 120 as drive sources.

When the brake pedal 174 is operated, the second motor generator 120 can be controlled to generate regenerative power.

Engine 100 is an internal combustion engine. As the fuel / air mixture burns in the combustion chamber, the crankshaft as the output shaft rotates. A catalyst 102 is attached to the engine 100. The catalyst 102 is provided in the exhaust pipe. The exhaust gas discharged from the engine 100 is purified by the catalyst 102 and then discharged outside the vehicle. The catalyst 102 exhibits a purification action by being warmed up to a specific temperature. The catalyst 102 is warmed up by utilizing the heat of the exhaust gas. The catalyst 102 is, for example, a three-way catalyst.

Engine 100, first motor generator 110, and second motor generator 120 are connected via power split mechanism 130. In other words, the first motor generator 110 and the second motor generator 120 are connected to the output shaft of the engine 100 via the power split mechanism 130. The power generated by the engine 100 is divided into two paths by the power split mechanism 130. One is a path for driving the front wheels 160 via the speed reducer 140. The other is a path for driving the first motor generator 110 to generate power.

The first motor generator 110 is a three-phase AC rotating electric machine including a U-phase coil, a V-phase coil, and a W-phase coil. First motor generator 110 generates power using the power of engine 100 divided by power split mechanism 130. The electric power generated by the first motor generator 110 is selectively used according to the running state of the vehicle and the remaining capacity of the battery 150. For example, during normal traveling, the electric power generated by first motor generator 110 becomes electric power for driving second motor generator 120 as it is. On the other hand, when the SOC of battery 150 is lower than a predetermined value, the electric power generated by first motor generator 110 is converted from AC to DC by an inverter described later. Thereafter, the voltage is adjusted by a converter described later and stored in the battery 150.

When the first motor generator 110 is acting as a generator, the first motor generator 110 generates a negative torque. Here, the negative torque means a torque that becomes a load on engine 100. When first motor generator 110 is supplied with electric power and acts as a motor, first motor generator 110 generates positive torque. Here, the positive torque means a torque that does not become a load on the engine 100, that is, a torque that assists the rotation of the engine 100. The same applies to the second motor generator 120.

The second motor generator 120 is a three-phase AC rotating electric machine including a U-phase coil, a V-phase coil, and a W-phase coil. Second motor generator 120 is driven by at least one of the electric power stored in battery 150 and the electric power generated by first motor generator 110.

The second motor generator 120 is connected to the front wheel 160 via the speed reducer 140. Therefore, the driving force of the second motor generator 120 is transmitted to the front wheels 160 via the speed reducer 140. As a result, the second motor generator 120 assists the engine 100 or causes the vehicle to travel by the driving force from the second motor generator 120. The rear wheels may be driven instead of or in addition to the front wheels 160.

When the accelerator opening is zero or when the brake pedal 174 is operated, the second motor generator 120 is controlled to generate regenerative power. When the second motor generator 120 generates regenerative power, the vehicle is regeneratively braked.

During regenerative braking of the vehicle, the second motor generator 120 is driven by the front wheels 160 via the speed reducer 140, and the second motor generator 120 operates as a generator. Accordingly, second motor generator 120 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by second motor generator 120 is stored in battery 150.

The power split mechanism 130 includes a planetary gear including a sun gear, a pinion gear, a carrier, and a ring gear. The pinion gear engages with the sun gear and the ring gear. The carrier supports the pinion gear so that it can rotate. The sun gear is connected to the rotation shaft of first motor generator 110. The carrier is connected to the crankshaft of engine 100. The ring gear is connected to the rotation shaft of second motor generator 120 and speed reducer 140.

The engine 100, the first motor generator 110, and the second motor generator 120 are connected via a power split mechanism 130 that is a planetary gear, so that the rotational speeds of the engine 100, the first motor generator 110, and the second motor generator 120 are increased. As shown in FIG. 2, the relationship is connected by a straight line in the alignment chart.

Referring back to FIG. 1, the battery 150 is an assembled battery configured by connecting a plurality of battery modules in which a plurality of battery cells are integrated in series. The voltage of the battery 150 is about 200V, for example. The battery 150 is charged with electric power supplied from the first motor generator 110 and the second motor generator 120. A capacitor may be used instead of or in addition to the battery 150.

The vehicle speed of the vehicle is detected by the vehicle speed sensor 180, and a signal representing the detection result is input to the ECU 170. The acceleration and deceleration of the vehicle are calculated by differentiating the vehicle speed.

Each wheel is provided with a braking device 190 for braking the vehicle using frictional force. In FIG. 1, only the braking device 190 provided on the right rear wheel is shown as a representative example. Since a known technique may be used for braking device 190, detailed description thereof will not be repeated here.

The electric system of the vehicle will be further described with reference to FIG. The vehicle is provided with a converter 200, a first inverter 210, a second inverter 220, and a system main relay 230.

Converter 200 includes a reactor, two npn transistors, and two diodes. One end of the reactor is connected to the positive electrode side of each battery, and the other end is connected to the connection point of the two npn transistors.

The two npn type transistors are connected in series. The npn transistor is controlled by the ECU 170. A diode is connected between the collector and emitter of each npn transistor so that a current flows from the emitter side to the collector side.

Note that, for example, an IGBT (Insulated Gate Bipolar Transistor) can be used as the npn transistor. A power switching element such as a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) can be used instead of the npn transistor.

When the electric power discharged from the battery 150 is supplied to the first motor generator 110 or the second motor generator 120, the voltage is boosted by the converter 200. Conversely, when charging the battery 150 with the electric power generated by the first motor generator 110 or the second motor generator 120, the voltage is stepped down by the converter 200.

The system voltage VH between the converter 200 and each inverter is detected by the voltage sensor 180. The detection result of voltage sensor 180 is transmitted to ECU 170.

First inverter 210 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, the V-phase arm, and the W-phase arm has two npn transistors connected in series. Between the collector and emitter of each npn-type transistor, a diode for flowing current from the emitter side to the collector side is connected. A connection point of each npn transistor in each arm is connected to an end portion different from neutral point 112 of each coil of first motor generator 110.

The first inverter 210 converts the direct current supplied from the battery 150 into an alternating current and supplies the alternating current to the first motor generator 110. The first inverter 210 converts the alternating current generated by the first motor generator 110 into a direct current.

The second inverter 220 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm and W-phase arm are connected in parallel. Each of the U-phase arm, the V-phase arm, and the W-phase arm has two npn transistors connected in series. Between the collector and emitter of each npn-type transistor, a diode for flowing current from the emitter side to the collector side is connected. A connection point of each npn transistor in each arm is connected to an end portion different from neutral point 122 of each coil of second motor generator 120.

The second inverter 220 converts the direct current supplied from the battery 150 into an alternating current and supplies the alternating current to the second motor generator 120. Second inverter 220 converts the alternating current generated by second motor generator 120 into a direct current.

The converter 200, the first inverter 210 and the second inverter 220 are controlled by the ECU 170.

The system main relay 230 is provided between the battery 150 and the converter 200. The system main relay 230 is a relay that switches between a state where the battery 150 and the electric system are connected and a state where the battery 150 is disconnected. When system main relay 230 is in an open state, battery 150 is disconnected from the electrical system. When system main relay 230 is in a closed state, battery 150 is connected to the electrical system.

The state of the system main relay 230 is controlled by the ECU 170. For example, when ECU 170 is activated, system main relay 230 is closed. When ECU 170 stops, system main relay 230 is opened.

Referring to FIG. 4, the control mode of engine 100 by ECU 170 will be further described. As shown in FIG. 4, when the output power of the vehicle is smaller than the engine start threshold value, engine 100 is temporarily stopped and the vehicle travels using only the driving force of second motor generator 120.

The output power is set as the power used for driving the vehicle. The output power is calculated by ECU 170 according to a map having, for example, the accelerator opening and the vehicle speed as parameters. The method for calculating the output power is not limited to this. Note that torque, acceleration, driving force, accelerator opening, and the like may be used instead of output power.

When the vehicle output power exceeds the engine start threshold, the engine 100 is driven. Thus, the vehicle travels using the driving force of engine 100 in addition to or instead of the driving force of second motor generator 120. Further, the electric power generated by first motor generator 110 using the driving force of engine 100 is directly supplied to second motor generator 120.

In addition, when the SOC of the battery 150 decreases, the engine 100 can be driven to generate power by the first motor generator 110 and charge the battery 150 even if the output power is smaller than the engine start threshold value. For example, when the SOC of battery 150 is lower than a threshold value, the vehicle is controlled in a forced charging mode in which battery 150 is charged until the SOC of battery 150 becomes equal to or greater than the threshold value. In the forced charging mode, the engine 100 is operated in principle, and the first motor generator 110 is controlled to generate power.

On the other hand, when the second motor generator 120 generates regenerative power during deceleration of the vehicle, the operation of the engine 100 is restricted. More specifically, when the driver performs a brake operation (operation of the brake pedal 174) and the second motor generator 120 generates regenerative power, the operation of the engine 100 is limited. As shown in FIG. 5, during regenerative power generation by second motor generator 120 (period from time T1 to T2 in FIG. 5), power generation using engine 100 and first generator 110 is prohibited, and as a result, engine 100 The driving of the first motor generator 110 is limited. Therefore, during regenerative power generation by second motor generator 120, engine 100 is stopped or idling to reduce the power generated by first motor generator 110 to zero. That is, the load operation of engine 100 is prohibited. Even when the forced charging mode is being executed, the load operation of the engine 100 is prohibited. In the present embodiment, the load operation means that engine 100 is operated with a load larger than that during idle operation.

In an operation state in which the forced charging mode is executed, that is, an operation state in which the SOC of the battery 150 is lower than the threshold value, the engine 100 is loaded to drive the first motor generator 110. As described above, when the second motor generator 120 regenerates power during deceleration, the engine 100 is stopped or idling. Therefore, when the second motor generator 120 performs regenerative power generation during deceleration in an operation state in which the forced charging mode is executed, the output power of the engine 100 is reduced. In the present embodiment, limiting the operation of engine 100 includes reducing the output power of engine 100.

As a result of the vehicle speed being reduced to a speed at which regenerative power generation is impossible, the operation of engine 100 continues to be restricted even after regenerative power generation by second motor generator 120 is completed at time T2 in FIG. More specifically, the operation of the engine 100 continues to be restricted while the driver is performing a brake operation (a period up to time T3 in FIG. 5).

Therefore, when the output power of engine 100 is reduced during the load operation in the forced charging mode, the state in which the output power of engine 100 is reduced is maintained even after the regenerative power generation by second motor generator 120 is completed. .

On the other hand, for example, when the vehicle speed is low or the deceleration is small, the second motor generator 120 may not generate regenerative power during deceleration of the vehicle. As shown in FIG. 6, after the brake operation is performed at time T4, if the second motor generator 120 does not generate regenerative power during deceleration of the vehicle, the engine 100 is operated and the first motor generator 110 generates power. For example, it is controlled in the forced charging mode.

As a result, in the driving state in which the forced charging mode can be executed, that is, in the state where the SOC of the battery 150 is lower than the threshold value, the output power of the engine 100 when the second motor generator 120 does not generate regenerative power during deceleration of the vehicle is It is made larger than the output power of engine 100 when second motor generator 120 regenerates power during deceleration of the vehicle.

With reference to FIG. 7, a process executed by ECU 170 in the present embodiment will be described.

In step (hereinafter step is abbreviated as S) 100, it is determined whether or not the brake pedal 174 has been operated. When brake pedal 174 is operated (YES in S100), it is determined in S102 whether second motor generator 120 performs regenerative power generation. For example, when the vehicle speed is equal to or higher than the threshold value, it is determined that second motor generator 120 generates regenerative power.

When second motor generator 120 generates regenerative power (YES in S102), the regenerative history flag is turned on in S104. Thereafter, in S106, it is determined whether or not the brake pedal 174 is operated and the regeneration history flag is on.

When brake pedal 174 is operated and the regeneration history flag is on (YES in S106), load operation of engine 100 is prohibited in S108. Therefore, power generation by first motor generator 110 is not executed.

Thereafter, while the brake pedal 174 is operated (YES in S100), the regeneration history flag is kept on even after the regenerative power generation of the second motor generator 120 is completed (NO in S102). Therefore, once second motor generator 120 generates regenerative power, the operation of engine 100 continues to be limited while brake pedal 174 is operated (YES in S106). This limits the increase in engine output during deceleration.

On the other hand, if brake pedal 174 is not operated (NO in S100), the regeneration history flag is turned off in S110. In this case (NO in S106), load operation of engine 100 is permitted in S112. Therefore, power generation by the first motor generator 110 is executed.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

100 engine, 110 first motor generator, 120 second motor generator, 130 power split mechanism, 140 speed reducer, 150 battery, 160 front wheel, 170 ECU, 172 accelerator pedal, 174 brake pedal, 180 vehicle speed sensor, 200 converter, 210th 1 inverter, 220 second inverter, 230 system main relay.

Claims

An engine (100);
An electric motor (120) coupled to the wheels (160);
When the electric motor (120) regenerates power during deceleration of the vehicle, the operation of the engine (100) is limited, and after the regenerative power generation by the electric motor (120) is completed, the operation of the engine (100) is stopped. A vehicle comprising a control unit (170) that continues to be restricted.
The control unit (170) outputs the output power of the engine (100) when the electric motor (120) does not generate regenerative power during deceleration of the vehicle, and the electric motor (120) regenerates during deceleration of the vehicle. The vehicle according to claim 1, wherein the vehicle is larger than the output power of the engine (100) when generating electric power.
The control unit (170) restricts the operation of the engine (100) when the electric motor (120) regenerates power during deceleration of the vehicle when a brake operation is performed by a driver, and the electric motor ( 2. The vehicle according to claim 1, wherein after the regenerative power generation according to 120) is finished, the operation of the engine (100) is continuously restricted while a brake operation is performed by a driver.
A generator (110) coupled to the output shaft of the engine (100);
A power storage device (150) for storing electric power regenerated by the electric motor (120) and electric power generated by the generator (110);
When the remaining capacity of the power storage device (150) is lower than a threshold value, the control unit (170) operates the engine (100) and controls the generator (110) to generate power,
The control unit (170) outputs the output of the engine (100) when the electric motor (120) regenerates power during deceleration of the vehicle in a state where the remaining capacity of the power storage device (150) is lower than a threshold value. 2. The vehicle according to claim 1, wherein the vehicle is maintained in a state in which the output power of the engine (100) is reduced after the power is reduced and regenerative power generation by the electric motor (120) ends.
A vehicle control method provided with an engine (100) and an electric motor (120) coupled to wheels (160),
Limiting the operation of the engine (100) when the electric motor (120) generates regenerative power during deceleration of the vehicle;
And a step of continuing to limit the operation of the engine (100) after regenerative power generation by the electric motor (120) is completed.