JP7123480B2 - Hybrid vehicle control device - Google Patents

Description

The present invention provides a hybrid vehicle in which electric power is supplied from a common power storage device to both a driving motor that drives drive wheels and a starting motor that motors (or cranks) an internal combustion engine. It relates to a control device.

In recent years, hybrid vehicles equipped with two power sources, an internal combustion engine and an electric motor, are gaining popularity. A series-type hybrid vehicle (see, for example, the following patent document) generates power by driving a generator with an internal combustion engine, stores the generated power in a power storage device (battery and/or capacitor), and supplies it to an electric motor. The electric motor rotates the axle of the vehicle, and by extension, the drive wheels, so that the vehicle travels.

JP 2016-064735 A

In a hybrid vehicle, even if the internal combustion engine does not burn fuel to generate rotational driving force, the vehicle can be driven by the rotational driving force output by the electric motor. Therefore, even during operation of the vehicle, the state where the operation of the internal combustion engine is stopped may continue.

An internal combustion engine is associated with a starting electric motor that rotationally drives the internal combustion engine when the engine is started. This electric motor is separate from the electric motor for running the vehicle. Both the driving motor and the starting motor are supplied with necessary electric power using a power storage device mounted on the vehicle as a power source.

In a compact car, it is difficult to install a large-sized power storage device or a plurality of power storage devices due to space restrictions in the vehicle body. Therefore, the power storage capacity and maximum output power of the power storage device are inevitably limited. In addition, a large-capacity power storage device is heavy, and it cannot be overlooked that it leads to an increase in cost.

When it becomes necessary to start the internal combustion engine while the vehicle is running by driving the drive wheels with the traction motor, the starter motor performs motoring of the internal combustion engine. A situation arises in which both of the main motors run at the same time. When power is supplied from a common power storage device to these electric motors, due to the limit of the output power of the power storage device, the electric power that should be supplied to the traction motor is taken away by the starting motor, and the driving force output by the traction motor is reduced. Therefore, there is concern that the acceleration of the vehicle will slow down.

SUMMARY OF THE INVENTION The present invention has been made for the first time by paying attention to the above problems, and it is an intended object of the present invention to avoid or suppress the deterioration of the acceleration performance of a vehicle when starting the internal combustion engine while the vehicle is running by an electric motor. there is

In the present invention, a traveling electric motor that supplies driving force for traveling to drive wheels, an internal combustion engine, a starting electric motor that supplies driving force for rotating the internal combustion engine when starting the internal combustion engine, and a traveling electric motor. Controls a hybrid vehicle equipped with a shared power storage device that supplies power to both the electric motor and the starting motor. When starting the internal combustion engine while the vehicle is running, While supplying power from the power storage device to the traction motor, the sum of the power supplied from the power storage device to both the traction motor and the starter motor does not exceed the upper limit of the power that the power storage device can output at that time. When the internal combustion engine is started while the vehicle is running, after the rotation speed of the internal combustion engine driven by the starting motor reaches a predetermined value, the power supplied from the power storage device to the starting motor is changed. suppressing the electric power supplied from the power storage device to the starting motor so that the rotation speed of the internal combustion engine is maintained at or near a predetermined value until the engine burns fuel and becomes able to rotate autonomously; After that, the rotational driving of the internal combustion engine by the starting motor is terminated, and the upper limit of the electric power that can be output from the power storage device is the sum of the electric power supplied from the power storage device to both the driving motor and the starting motor at normal times. A control device for a hybrid vehicle is configured to pull up for a predetermined time after reaching the point of time .

According to the present invention, it is possible to avoid or suppress deterioration in the acceleration performance of the vehicle when starting the internal combustion engine while the vehicle is running by the electric motor.

1 is a diagram showing an outline of a series-type hybrid vehicle in one embodiment of the present invention; FIG. FIG. 4 is a diagram showing a transition of electric power supplied from a power storage device to an electric motor when an internal combustion engine is started as a reference example related to the same embodiment; FIG. 4 is a diagram showing the transition of electric power supplied from the power storage device to the electric motor when the internal combustion engine is started in the same embodiment; FIG. 4 is a diagram showing changes in rotation speed when the internal combustion engine is started in the same embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of main systems of a hybrid vehicle in this embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generating motor generator 2 that is driven by the internal combustion engine 1 to generate power, a power storage device 3 that stores the electric power generated by the power generating motor generator 2, the power generating motor generator 2 and/or Alternatively, a motor-generator 4 for traveling is provided that receives electric power supply from the power storage device 3 to drive the axles of the vehicle and, in turn, the drive wheels 62 .

The hybrid vehicle of the present embodiment is a series hybrid electric vehicle that uses the internal combustion engine 1 only for power generation, and the drive wheels 62 of the vehicle are exclusively supplied with driving force for running from the motor generator 4 for running. That is, the traveling motor generator 4 corresponds to the traveling electric motor. The internal combustion engine 1 and the drive wheels 62 are mechanically separated from each other, and originally rotational driving force is not transmitted between them. Therefore, during operation of the vehicle with the ignition switch (power switch or ignition key) turned on, in other words, even when the vehicle is in a state in which the vehicle can travel by depressing the accelerator pedal, the power storage device 3 is sufficiently charged, the operation of the internal combustion engine 1 involving combustion of fuel is not performed.

The internal combustion engine 1 is, for example, a four-stroke engine containing multiple cylinders. A crankshaft, which is an output shaft of the internal combustion engine 1, is mechanically connected to an input shaft of a motor generator 2 for power generation. Rotational driving force is transmitted from the internal combustion engine 1 to the motor generator 2 for power generation, so that the motor generator 2 generates electric power. The power generation motor generator 2 also functions as an electric motor that generates rotational driving force to rotationally drive the crankshaft of the internal combustion engine 1 . For example, the power generation motor generator 2 may perform motoring (cranking) to start the stopped internal combustion engine 1 . That is, the electric power generating motor generator 2 corresponds to the starting electric motor. It should be noted that a starter motor (starter motor), which is a dedicated starting motor for motoring the internal combustion engine 1, may be attached to the internal combustion engine 1 separately from the motor generator 2 for power generation.

The generator inverter 21 converts the AC power generated by the motor generator 2 for power generation into DC power and inputs the DC power to the power storage device 3 . In addition, the generator inverter 21 converts the DC power output from the power storage device 3 into AC power and inputs it to the power generation motor generator 2 when operating the power generation motor generator 2 as an electric motor.

The running motor generator 4 generates a driving force for running the vehicle and inputs it to the driving wheels 62 via the speed reducer 61 . In addition, the running motor generator 4 rotates together with the drive wheels 62 to generate electric power, and recovers the kinetic energy of the vehicle as electrical energy. Electric power generated by this regeneration is charged in the power storage device 3 .

The drive inverter 41 converts the DC power supplied from the power storage device 3 and/or the generator inverter 21 into AC power and inputs the AC power to the motor generator 4 for running. In addition, the drive inverter 41 converts the AC power generated by the traveling motor generator 4 when the vehicle is regeneratively braked into DC power and inputs the DC power to the power storage device 3 .

The generator inverter 21 and the drive inverter 41 form part of a PCU (Power Control Unit).

The power storage device 3 is a battery and/or a capacitor or the like. The power storage device 3 charges and stores electric power generated by each of the motor generator 2 for power generation and the motor generator 4 for running. Power storage device 3 also discharges electric power for operating motor generator 2 for electric power generation and motor generator 4 for running as electric motors, and supplies necessary electric power to motor generators 2 and 4 . If a starter motor is attached to the internal combustion engine 1 as a starting motor in addition to the motor generator 2 for power generation, the power storage device 3 supplies necessary power to the starter motor.

An ECU (Electronic Control Unit) 0, which is a control device for controlling the internal combustion engine 1, the motor generator 2 for power generation, the power storage device 3, the inverters 21 and 41, and the motor generator 4 for running, includes a processor, a memory, an input interface, an output interface, and the like. It is a microcomputer system having In the ECU 0, a plurality of ECUs (for example, controllers that individually control the internal combustion engine 1, the motor generators 2 and 4, the power storage device 3, etc.) communicate with each other via an electric communication line such as a CAN (Controller Area Network). It may be connected as possible.

The ECU 0 detects the amount of depression of the accelerator pedal by the driver detected via a sensor, the current vehicle speed, the slope of the road surface, the amount of electricity stored in the electricity storage device 3, the power generated by the motor generator 2, and the like. The rotational driving force output by the traveling motor generator 4, the rotational driving force output by the internal combustion engine 1, and the electric power generated by the power generating motor generator 2 are controlled to increase or decrease. If the power storage device 3 is currently storing a sufficient amount of electric charge and the output driving force required of the motor generator 4 for traveling is not maximum, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is not operated. .

On the other hand, when the amount of electric charge currently stored in the power storage device 3 is below a predetermined amount, or when the output driving force required of the traveling motor generator 4 is maximum, the internal combustion engine 1 is started. In addition, fuel is supplied to the internal combustion engine 1 to burn it, and the rotational driving force output from the internal combustion engine 1 drives the power generation amount motor generator 2 to generate power and charge the power storage device 3, or the traveling motor generator It becomes necessary to increase the power supplied to 4.

An attempt is made to start the internal combustion engine 1 while fuel is not being supplied to the internal combustion engine 1 and the vehicle is running by driving the drive wheels 62 with the motor generator 4 for running. At this time, the motor generator 2 for power generation or the starter motor performs motoring for starting the internal combustion engine 1 . As a result, a situation arises in which the traveling motor generator 4 and the electric power generating motor generator 2 or the starter motor operate at the same time. Power is supplied to these electric motors 2 and 4 from the same power storage device 3 . There is an upper limit to the power that the power storage device 3 can output. Therefore, if the internal combustion engine 1 is simply motored by supplying the required electric power to the motor generator 2 for power generation or the starter motor, the electric power supplied to the motor generator 4 for running is reduced by that amount, and the motor generator 4 for running is reduced. There is a risk that the output driving force will decrease and the acceleration of the running vehicle will slow down. This problem may become apparent in compact cars in which it is difficult to mount a large amount of battery cells, capacitors, or the like as the power storage device 3 .

Therefore, when starting the internal combustion engine 1 while the vehicle is running, the ECU 0 of the present embodiment supplies electric power required for running from the power storage device 3 to the motor generator 4 for running, and The power storage device 3 is supplied to the power generation motor generator 2 or the power generation motor generator 2 or the power generation motor generator 2 or the power generation motor generator 2 or Increase or decrease the power supplied to the starter motor.

FIG. 2 shows an example of control of electric power supplied to the motor generator 2 or the starter motor when the internal combustion engine 1 is started. In FIG. 2 , a solid line P represents changes in power output from the power storage device 3 , and a dashed line M represents changes in power supplied from the power storage device 3 to the traveling motor generator 4 . The power that can be supplied from the power storage device 3 to the motor generator 2 or the starter motor is equal to the former P minus the latter M. That is, the halftone dot area in the figure represents the electric power supplied from the power storage device 3 to the electric power generating motor generator 2 or the starter motor. t ₀ is the time point at which the motor generator 2 for power generation or the starter motor starts motoring the internal combustion engine 1 in order to start the internal combustion engine 1 . t ₁ is the time when the motor generator 2 for power generation or the starter motor finishes motoring the internal combustion engine 1, that is, the time when the internal combustion engine 1 burns fuel and can rotate independently. In practice, the length of the period from time t ₀ to time t ₁ is less than tenths of a second (0.3 seconds if power storage device 3 has not deteriorated over time).

A dashed line L represents the upper limit of the power that the power storage device 3 can output. The maximum output power of the power storage device 3 depends on the amount of charge (or state of charge) stored in the power storage device 3 at that time, the temperature of the power storage device 3, and the like. The maximum output power increases as the amount of charge stored in the power storage device 3 increases, and conversely decreases as the amount of charge stored decreases. The amount of charge currently stored in the power storage device 3 can be estimated by sensing the terminal current of the power storage device 3 and integrating it over time, or by sensing the terminal voltage of the power storage device 3 . Further, when the power storage device 3 is a lithium ion battery, the lower the temperature thereof, the smaller the maximum output power. The current temperature of the power storage device 3 can be sensed via a temperature sensor attached in advance.

The ECU 0 sets an upper limit L of power that can be output by the power storage device 3 within the range of the current maximum output power of the power storage device 3 . The upper limit L is set to a value lower than the maximum output power to some extent or more in order to keep the life of the power storage device 3 as long as possible in normal times. However, the upper limit L is not always constant, and may be temporarily raised according to power demand. As shown in FIG. 2, the ECU 0 according to the present embodiment is controlled at time t when the sum P of electric power supplied to both the motor generator 4 for traveling and the motor generator 2 for power generation or the starter motor reaches the normal upper limit L. ₂ and thereafter, the upper limit L is raised for a predetermined period of time (for example, one second).

In the example shown in FIG. 2, the ECU 0 determines the electric power to be supplied from the power storage device 3 to the power generation motor generator 2 or the starter motor based on the upper limit L of the electric power that the power storage device 3 can output at that time. It is suppressed to a value obtained by subtracting the power M to be generated, or to a magnitude less than or equal to the subtracted value and in the vicinity thereof. That is _, after time t3 when the sum P of electric power supplied to both the motor generator 4 for traveling and the motor generator 2 for power generation or the starter motor reaches the upper limit L (which is higher than that in normal times), the sum P is The electric power supplied to the power generation motor generator 2 or the starter motor is reduced so as to be clipped to the upper limit L.

At this time, the electric power M supplied to the traveling motor-generator 4 is not reduced from the electric power required by the traveling motor-generator 4 . In short, by reducing the electric power supplied to the generator motor generator 2 or the starter motor for motoring the internal combustion engine 1, the electric power M to be supplied to the running motor generator 4 is secured, and the running motor generator 4 outputs It secures the rotational driving force to The ECU 0 senses the amount of depression of the accelerator pedal by the driver, and estimates the driving force to be output by the traveling motor generator 4, in other words, the magnitude of the driving force requested by the driver. Based on the requested driving force and the current sensed rotational speed of the traveling motor generator 4, the magnitude of the electric power M required for the traveling motor generator 4 to output the requested driving force is calculated. . Thus, the magnitude of the power to be supplied to the motor generator 2 for power generation or the starter motor is calculated within a range obtained by subtracting the power M to be supplied to the motor generator 4 for running from the upper limit L of the output power of the power storage device 3. , the motor-generator 4 for running and the motor-generator 2 for power generation or the starter motor.

Motoring for starting the internal combustion engine 1 is performed when the rotational speed of the crankshaft of the internal combustion engine 1 being sensed rises to a threshold value or more and the crankshaft of the internal combustion engine 1 rotates a predetermined number of times or more or at a predetermined angle from the start of motoring. It ends when it rotates more than. The latter condition may be replaced with when the current stroke or piston position of each cylinder of the internal combustion engine 1 is completed. It is necessary to know the current stroke of each cylinder in order to inject fuel at appropriate timing according to the stroke of each cylinder and to ignite and burn fuel at appropriate timing. Cylinder discrimination is performed by a crank angle sensor that emits a pulse signal each time the crankshaft rotates by a predetermined angle (for example, 10°CA), and a crank angle sensor that emits a pulse signal each time the crankshaft rotates by a predetermined angle (one rotation of the camshaft divided by the number of cylinders). Angle: In the case of a three-cylinder engine, this is done using a cam angle sensor that emits a pulse signal each time it rotates by 120° (240° CA). Since the method for discriminating cylinders is well known, a description thereof will be omitted here. It is necessary to rotate about a rotation. The latter condition implies this.

3 and 4 show another example of control of electric power supplied to the power generating motor generator 2 or the starter motor when the internal combustion engine 1 is started. In FIG. 3, the solid line P ' represents the transition of the power output from the power storage device 3, the dashed line M represents the transition of the power supplied from the power storage device 3 to the traveling motor generator 4, and the chain line L represents the power output from the power storage device 3. It represents the upper limit of power that can be used. A region with halftone dots represents electric power supplied from the power storage device 3 to the power-generating motor generator 2 or the starter motor. t ₁ ' is the point of time when the power generating motor generator 2 or the starter motor ends the motoring of the internal combustion engine 1, and has the same meaning as t ₁ in FIG.

In the example shown in FIG. 2, the power M required by the motor-generator 4 for running is secured as the power supplied to the motor-generator 2 for power generation or the starter motor, but the total sum P of the power supply is less than the output of the power storage device 3. The electric power is increased to the extent that it does not exceed the upper limit L so that the internal combustion engine 1 can be started as quickly as possible. On the other hand, in the example shown in FIGS. 3 and ₄ , after the time _t0 when the motoring of the internal combustion engine 1 is started, until the time t4 when the rotational speed of the crankshaft of the internal combustion engine 1 reaches the predetermined value S, , power supply to the motor generator 2 or the starter motor within the limit that the sum P 1 ′ of power supply does not exceed the upper limit L of the output power of the power storage device 3 . However, after the time t4 when the rotation speed of the crankshaft of the internal combustion engine 1 reaches the predetermined value S, the rotation speed of the crankshaft of the internal combustion engine ₁ is kept at the predetermined value until the time t1' when the motoring of the internal combustion engine ₁ ends. The electric power supplied from the power storage device 3 to the electric power generating motor generator 2 or the starter motor is suppressed so that the electric power is kept at or near the value S.

The predetermined value S corresponds to a threshold value of the engine speed at which the momentum of rotation of the internal combustion engine 1 is equal to or higher than the minimum necessary and sufficient limit for starting the engine. As depicted by the solid line N' in FIG. ₄ , the rotation speed of the crankshaft of the internal combustion engine ₁ is substantially constant or does not significantly accelerate during the period from time t4 to time t1'. In order to maintain the rotational speed of the crankshaft of the internal combustion engine 1 near the predetermined value S, the crankshaft of the internal combustion engine 1 has rotated a predetermined number of times or more or a predetermined angle or more since the start of motoring (the rotation speed of each cylinder of the internal combustion engine 1 is Satisfaction of the start completion condition "Cylinder discrimination for obtaining the current stroke or piston position has been completed" will be somewhat delayed. Incidentally, the dashed line N in FIG. 4 indicates transition of the rotation speed of the crankshaft of the internal combustion engine 1 according to the example shown in FIG.

Through such control, the electric power supplied to the motor generator 2 or the starter motor for motoring the internal combustion engine 1 is reduced to the necessary minimum. Therefore, the electric power M required by the motor-generator 4 for running can be supplied to the motor-generator 4 for running, and the driving force for running the vehicle can be secured.

After the time points t ₁ and t ₁ ' when the start of the internal combustion engine 1 is completed and the motoring of the internal combustion engine 1 is finished, the electric power supplied from the power storage device 3 to the power generation motor generator 2 or the starter motor cannot be reduced to zero. Needless to say.

In the present embodiment, a driving motor (motor generator for driving) 4 for supplying driving force for driving to the drive wheels 62, an internal combustion engine 1, and a motor for rotating the internal combustion engine 1 when the internal combustion engine 1 is started are provided. Controls a hybrid vehicle having a starter motor (generator motor generator or starter motor) 2 that supplies driving force, and a shared power storage device 3 that supplies electric power to both the drive motor 4 and the starter motor 2. When the internal combustion engine 1 is started while the vehicle is running, electric power M required for running the vehicle is supplied from the power storage device 3 to the running electric motor 4 while the power storage device 3 supplies the running electric motor 4 with electric power M. and the electric power supplied to the starter motor 2 from the power storage device 3 to the starter motor 2 so that the sum P 1 , P′ of the power supplied to both the power storage device 3 and the starter motor 2 does not exceed the upper limit L of the power that the power storage device 3 can output at that time. A control device 0 for a hybrid vehicle that changes the . According to the present embodiment, it is possible to avoid or suppress deterioration in acceleration performance of the vehicle when the internal combustion engine 1 is started while the vehicle is running by the electric motor 4 .

The present invention is not limited to the embodiments detailed above. For example, in the above embodiment, a series hybrid vehicle in which the internal combustion engine 1 is permanently disconnected from the drive wheels 62 of the vehicle is assumed, but the application of the present invention is not limited to series hybrid vehicles. The present invention can be applied to general vehicles in which the operation of the internal combustion engine can be stopped even temporarily during operation of the vehicle including running. Even in hybrid vehicles of the parallel hybrid system and series parallel hybrid system (split system), it is possible to stop the operation of the internal combustion engine without burning fuel while the vehicle is in operation. As long as the starting electric motor receives power supply from a common power storage device, the present invention is generally applicable.

In addition, the specific configuration of each part and the content of processing can be modified in various ways without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to the control of hybrid vehicles.

0... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1... Internal combustion engine 2... Electric motor for starting (motor generator for electric power generation)
3 power storage device 4 traveling motor (traveling motor generator)

Claims (1)

A traveling electric motor that supplies driving force for traveling to drive wheels, an internal combustion engine, a starting electric motor that supplies driving force for rotating the internal combustion engine when starting the internal combustion engine, a traveling electric motor, and a starting electric motor Controlling a hybrid vehicle equipped with a shared power storage device that supplies power to both electric motors,
When the internal combustion engine is started while the vehicle is running, the electric power required for running is supplied from the power storage device to the traction motor, and the amount of power supplied from the power storage device to both the traction motor and the starter motor. The power supplied from the power storage device to the starting motor is changed so that the sum does not exceed the upper limit of the power that the power storage device can output at that time ,
When the internal combustion engine is started while the vehicle is running, after the rotation speed of the internal combustion engine driven by the starter motor reaches a predetermined value, the internal combustion engine burns fuel and becomes able to rotate independently. suppressing the electric power supplied from the power storage device to the starting motor so that the rotational speed of the internal combustion engine is maintained at or near a predetermined value for the period of time, and then stopping the rotational driving of the internal combustion engine by the starting motor;
Further, the hybrid vehicle control device raises the upper limit of the power that can be output from the power storage device for a predetermined time after the sum of the power supplied from the power storage device to both the driving motor and the starter motor reaches the normal upper limit. .

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