JP2021020599A - Control method of electric vehicle and driving system of electric vehicle - Google Patents

Abstract

To suppress the generation of shock when switching a traveling mode due to a deviation between the actual torque and a command value of an internal combustion engine.SOLUTION: A driving system of an electric vehicle includes an internal combustion engine (1), a generation motor (2) that generates electric power by receiving the power of the internal combustion engine (1), and a traveling motor (3) driven by the electric power generated by the generation motor (2), and is configured to be switchable between a series hybrid mode and an engine direct connection mode. When switching from the series hybrid mode to the engine direct connection mode, and during traveling in the engine direct connection mode, either of a first correcting method that corrects a deviation of the total driving torque transmitted to a driving wheel (7) due to difference between target torque and actual torque of the internal combustion engine (1), by increasing/decreasing the torque of the generation motor (2) or a second correcting method that corrects it by increasing/decreasing the actual torque of the internal combustion engine (1), is selected and executed on the basis of a battery charging state.SELECTED DRAWING: Figure 8

Description

The present invention relates to a control method and a drive system for an electric vehicle.

A driving mode (series hybrid mode) in which the generator is driven by the power of the internal combustion engine and an electric motor for traveling is operated by the electric power generated by the generator, and a driving mode (directly connected to the engine) in which the drive wheels are driven by the power of the internal combustion engine. A drive system that can switch between mode) and is known. Patent Document 1 discloses a control method for suppressing a shock caused by a fluctuation in power transmitted to a drive wheel when the traveling mode is switched in the drive system. In the control of the above document, the power transmitted from the internal combustion engine to the drive wheels and the power transmitted from the electric motor for traveling to the drive wheels are controlled so that the power transmitted to the drive wheels does not change when the travel mode is switched. I'm changing. For example, when switching from the engine direct connection mode to the series hybrid mode, the power transmitted from the internal combustion engine to the drive wheels is reduced, while the power transmitted from the electric motor for traveling to the drive wheels is increased. Then, after the power transmitted from the internal combustion engine to the drive wheels becomes zero, the power transmission path from the internal combustion engine to the drive wheels is released. As a result, when the traveling mode is switched, it is possible to suppress the occurrence of a shock due to a change in the power transmitted to the drive wheels.

International Publication No. 2011/074483

However, the control in the above document is based on the premise that the internal combustion engine generates torque according to the command value. The actual torque of the internal combustion engine may deviate from the command value due to factors such as the temperature and humidity of the atmosphere and the temperature of the cooling water.

That is, in the control of the above document, when the actual torque of the internal combustion engine deviates from the command value, the power transmitted to the drive wheels by the amount of the deviation of the torque of the internal combustion engine before and after the switching of the traveling mode. Will change and a shock will occur.

Therefore, in the present invention, even when the actual torque of the internal combustion engine deviates from the command value, a control method and a drive system capable of suppressing the occurrence of a shock due to a change in power transmitted to the drive wheels when switching the traveling mode. The purpose is to provide.

According to an aspect of the present invention, an internal combustion engine, a power generation motor arranged so as to be able to generate power by receiving the power of the internal combustion engine, and a traveling motor arranged to be driveable by the power generated by the power generation motor. A series hybrid mode in which the internal combustion engine and the drive wheels are connected to each other via the first clutch so that the power of the traveling motor is transmitted to the drive wheels to travel, and the power of the internal combustion engine and the power of the power generation motor. Is configured to be switchable between the engine direct connection mode in which the engine is directly connected to the drive wheels, and the engine direct connection mode provides a control method for an electric vehicle that releases the first clutch in the series hybrid mode and engages the first clutch in the engine direct connection mode. To. In this embodiment, the deviation of the total drive torque transmitted to the drive wheels due to the difference between the target torque and the actual torque of the internal combustion engine when switching from the series hybrid mode to the engine direct connection mode and when running in the engine direct connection mode. The battery charge state is either the first correction method that corrects by increasing or decreasing the actual torque of the power generation motor or the second correction method that corrects the deviation of the total drive torque by increasing or decreasing the torque of the internal combustion engine. Select and execute based on.

According to another aspect, a drive system for an electric vehicle is provided.

According to each of the above aspects, it is possible to suppress the occurrence of a shock caused by a change in power transmitted to the drive wheels when the traveling mode is switched.

FIG. 1 is a schematic view showing an overall configuration of a drive system for an electric vehicle according to an embodiment of the present invention. FIG. 2 is a diagram showing the operation of the drive system in the series hybrid mode. FIG. 3 is a diagram showing the operation of the drive system in the engine direct connection mode. FIG. 4 is a diagram showing a traveling mode according to the operating region of the drive system. FIG. 5 is a time chart illustrating the operation of switching from the series hybrid mode to the engine direct connection mode. FIG. 6 is a time chart when the actual engine torque is smaller than the target engine torque when switching from the series hybrid mode to the engine direct connection mode. FIG. 7 is a time chart when the actual engine torque is larger than the target engine torque when switching from the series hybrid mode to the engine direct connection mode. FIG. 8 is a flowchart showing a control routine executed in the torque replacement phase of the mode switching control from the series hybrid mode to the engine direct connection mode. FIG. 9 is a first time chart when the control routine of FIG. 8 is executed. FIG. 10 is a second time chart when the control routine of FIG. 8 is executed. FIG. 11 is a third time chart when the control routine of FIG. 8 is executed. FIG. 12 is a fourth time chart when the control routine of FIG. 8 is executed. FIG. 13 is a flowchart showing a modified example of the control routine of FIG. FIG. 14 is a time chart illustrating the operation of switching from the engine direct connection mode to the series hybrid mode. FIG. 15 is a flowchart showing a control routine executed in the torque replacement phase of the mode switching control from the engine direct connection mode to the series hybrid mode. FIG. 16 is a first time chart when the control routine of FIG. 15 is executed. FIG. 17 is a second time chart when the control routine of FIG. 15 is executed. FIG. 18 is a third time chart when the control routine of FIG. 15 is executed. FIG. 19 is a fourth time chart when the control routine of FIG. 15 is executed. FIG. 20 is a fifth time chart when the control routine of FIG. 15 is executed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment)
The first embodiment will be described with reference to FIGS. 1 to 13.

FIG. 1 shows the overall configuration of a drive system S for an electric vehicle according to an embodiment of the present invention.

The drive system (hereinafter, simply referred to as “drive system”) S according to the present embodiment is mounted on an electric vehicle to form a propulsion device for the vehicle. The drive system S includes an internal combustion engine (hereinafter, simply referred to as “engine”) 1, an electric motor for power generation (hereinafter, referred to as “power generation motor”) 2, and an electric motor for traveling (hereinafter, referred to as “travel motor”) 3. , Equipped with.

The internal combustion engine 1 has its crankshaft 11 connected to the rotating shaft 21 of the power generation motor 2 via a gear train Ga composed of a plurality of gears. The torque of the engine 1 is transmitted to the power generation motor 2 at a predetermined gear ratio through the gear train Ga to operate the power generation motor 2. In the present embodiment, the connection between the engine 1 and the power generation motor 2 via the gear train Ga is permanent, that is, cannot be cut off.

The power generation motor 2 is electrically connected to the traveling motor 3 and also electrically connected to the battery 4, and the electric power generated by receiving the power supply from the engine 1 is generated by the traveling motor 3 or the battery. Supply to 4. The supply of electric power from the power generation motor 2 to the traveling motor 3 and the supply of electric power from the power generation motor 2 to the battery 4 can be executed according to the operating state of the vehicle, the charging state of the battery 4, and the like. FIG. 1 schematically shows an electrical connection between a power generation motor 2, a traveling motor 3, and a battery 4 by an alternate long and short dash line.

The traveling motor 3 is electrically connected to the battery 4, and its rotating shaft 31 is connected to the ring gear of the differential 5 via a gear train Gb composed of a plurality of gears. The torque of the traveling motor 3 is transmitted to the differential 5 at a predetermined gear ratio through the gear train Gb, and is further distributed to the left and right drive shafts 6 and 6 via the differential 5 to rotate the drive wheels 7 and rotate the vehicle. Promote. In the present embodiment, the traveling motor 3 is composed of a motor generator that can operate not only as a generator but also as an electric motor, propels the vehicle, and receives power from the drive wheels 7 via the gear train Gb. , It is also possible to generate electricity. It is possible to supply the electric power generated by the traveling motor 3 to the battery 4 and use it for charging the battery 4.

Further, in the present embodiment, the crankshaft 11 of the engine 1 is connected to the ring gear of the differential 5 via a gear train Gc composed of a plurality of gears. The torque of the engine 1 is transmitted to the differential 5 through the gear train Gc at a predetermined gear ratio and distributed to the left and right drive shafts 6 and 6 via the differential 5, so that the drive wheels 7 are rotated and the vehicle is propelled. Will be done.

In the present embodiment, clutches C1 and C2 are interposed in the gear train Gc and the gear train Gb, respectively, the engine 1 and the drive wheel 7 are connected via the gear train Gc, and the traveling motor 3 and the drive wheel 7 are connected. The connection via the gear train Gb is configured to be cut off by the clutches C1 and C2, respectively. The clutches C1 and C2 may be meshing type clutches, and a dog clutch can be exemplified as applicable to the clutches C1 and C2. In the present embodiment, a dog clutch is used as the clutches C1 and C2. This is because the friction due to so-called dragging in the released state is small, the cost is low, and the configuration can be made compact. The clutch C1 provided in the gear train Gc on the engine 1 side constitutes the "first clutch" according to the present embodiment, and the clutch C2 provided in the gear train Gb on the traveling motor 3 side constitutes the "first clutch" according to the present embodiment. "2 clutches" are configured.

The operation of the engine 1, the power generation motor 2 and the traveling motor 3, and the states of the clutch C1 and the clutch C2 are electronically controlled by the controller 101 as a control unit. Although not limited to this, the controller 101 is composed of a central processing unit (CPU), various storage units such as ROM and RAM, an input / output interface, and the like as an electronic control unit.

Information on various parameters indicating the driving state of the vehicle is input to the controller 101. In the present embodiment, a signal indicating the amount of operation of the accelerator pedal by the driver (hereinafter referred to as "accelerator opening") APO, a signal indicating the running speed of the vehicle (hereinafter referred to as "vehicle speed") VSP, and the rotation speed Neng of the engine 1 are used. A signal indicating, a signal indicating the rotation speed Ngen of the power generation motor 2, and a signal indicating the rotation speed Nmg of the traveling motor 3 are input to the controller 101. Then, in order to detect various parameters, the accelerator opening sensor 201 that detects the accelerator opening APO, the vehicle speed sensor 202 that detects the vehicle speed VSP, and the rotation speed Neng of the engine 1 are set to the rotation speed per unit time (hereinafter, "engine rotation speed"). ”), The engine rotation speed sensor 203 that detects the rotation speed Ngen of the power generation motor 2 as the power generation motor rotation speed, and the power generation motor rotation speed sensor 204 that detects the rotation speed Nmg of the travel motor 3 as the travel motor rotation speed. A motor rotation speed sensor 205 is provided.

The controller 101 executes predetermined calculations based on various input signals to control the operations of the engine 1, the power generation motor 2, and the traveling motor 3, and also controls the states of the clutches C1 and C2.

In the present embodiment, it is possible to switch the driving mode between the series hybrid mode and the engine direct connection mode during actual driving. In the series hybrid mode, the traveling motor 3 is used as the drive source of the vehicle, and in the engine direct connection mode, the engine 1 is basically used as the drive source of the vehicle.

2 and 3 show the operation of the drive system S according to the traveling mode, FIG. 2 shows the operation in the series hybrid mode, and FIG. 3 shows the operation in the engine direct connection mode. In FIGS. 2 and 3, the path through which power is transmitted is indicated by a thick broken line with an arrow, and the arrow indicates the direction in which power is transmitted.

In the series hybrid mode, as shown in FIG. 2, the clutch C1 is released while the clutch C2 is engaged so that the torque of the engine 1 can be transmitted to the power generation motor 2 through the gear train Ga and the torque of the traveling motor 3. Can be transmitted to the differential 5 and the drive wheels 7 through the gear train Gb.

On the other hand, in the engine direct connection mode, as shown in FIG. 3, the clutch C1 is engaged while the clutch C2 is released so that the torque of the engine 1 can be transmitted to the differential 5 and the drive wheels 7 through the gear train Gc. Here, since the clutch C2 on the power transmission path connecting the traveling motor 3 and the driving wheels 7 is in a disengaged state, the power transmission between the traveling motor 3 and the driving wheels 7 is interrupted. It is avoided that the traveling motor 3 is rotated with the rotation of the drive wheels 7. As a result, friction is reduced as compared with the case where the traveling motor 3 is rotated, so that the fuel efficiency performance of the engine 1 is improved. In the engine direct connection mode, when the power generation motor 2 is composed of a motor generator, it is possible to transmit the torque of not only the engine 1 but also the power generation motor 2 to the drive wheels 7 through the gear trains Ga and Gc.

The switching between the series hybrid mode and the engine direct connection mode is executed by switching the engagement and disengagement states of the clutches C1 and C2 based on the signal from the controller 101.

FIG. 4 shows a traveling mode according to the driving area of the vehicle.

Roughly speaking, the engine direct connection mode is selected in the high speed range, and the series hybrid mode is selected in the other areas. In the present embodiment, the engine direct connection mode is selected in the high-speed region B in which the load is relatively low, and the series hybrid mode is selected in the other regions A. The controller 101 determines the driving areas A and B to which the driving state of the vehicle belongs based on the vehicle speed VSP and the accelerator opening APO, and switches the traveling mode according to the determination result.

Area A is a region in which the series hybrid mode has better fuel efficiency of the engine 1 than the engine direct connection mode, and region B is a region in which the engine direct connection mode has better fuel efficiency than the series hybrid mode.

The reason why the engine direct connection mode has better fuel efficiency than the series hybrid mode in region B is as follows. When traveling at high speed and with a low load, the operating point of the engine 1 approaches the operating point having an excellent fuel consumption rate. Therefore, when the conversion efficiency to electricity is taken into consideration, it is better to directly transmit the torque of the engine 1 to the drive wheels 7 and 7 than to convert the power of the engine 1 into electricity by the power generation motor 2 to operate the traveling motor 3. This is because the system efficiency as a drive system is increased.

The control related to the switching of the traveling mode (hereinafter referred to as “mode switching control”) will be described below. First, the problems that occur during basic mode switching control and mode switching will be described using the time charts of FIGS. 5 to 7, and then the problems will be solved using the flowchart of FIG. 8 and the time charts of FIGS. 9 to 12. The method of solving the problem will be explained.

5 to 7 are time charts when switching from the series hybrid mode HEV to the engine direct connection mode ENG.

As shown in FIG. 5, the series hybrid mode HEV is switched to the engine direct connection mode ENG after a mode switching period. The mode switching period includes a rotation synchronization phase, a clutch engagement phase, a torque replacement phase, and a clutch release phase.

When a request for switching to the engine direct connection mode ENG occurs at the timing T1 during traveling in the series hybrid mode HEV, the rotation synchronization phase is started. In the rotation synchronization phase, the rotation speed of the power generation motor 2 (hereinafter referred to as the rotation speed of the power generation motor) Ngen is reduced by controlling the power generation torque Trqgen of the power generation motor 2, and the output rotation speed Nout corresponding to the rotation speed of the drive shaft 6 is reduced. Get closer to. The power generation motor rotation speed Ngen referred to here is a conversion of the engine rotation speed Neng into the rotation speed of the power generation motor 2 based on the gear ratio of the gear train Gc. When the difference between the output rotation speed Nout and the power generation motor rotation speed Ngen decreases to a predetermined value, or the difference in rotation speed is equal to or less than a predetermined value continues for a predetermined time (timing T2). Assuming that the rotation synchronization is completed, the process shifts to the clutch engagement phase and the clutch C1 is engaged. When the engagement of the clutch C1 is completed (timing T3), the torque replacement phase is started. Here, the state in which the clutch C2, which is the clutch on the release side, is engaged is maintained from the rotation synchronization phase to the clutch engagement phase, and in the torque replacement phase, a state in which both the clutches C1 and C2 are engaged is formed. Then, in the present embodiment, a command to release the clutch C2 is output at the same time as the transition to the torque replacement phase (timing T3). However, the clutch C2 maintains the engaged state until the torque of the traveling motor 3 (hereinafter referred to as traveling motor torque) Trqmg becomes zero.

In the torque replacement phase, the torque applied to the drive shaft 6, that is, the torque of the power generation motor 2 (hereinafter referred to as the power generation motor torque) Trqgen is increased so as to keep the total drive torque Trqtl of the vehicle constant, while the traveling motor torque. Decrease Trqmg. At this time, the engine torque Trqeng is maintained constant. That is, as the power generation motor torque Trqgen decreases, the engine torque Trqeng transmitted to the drive shaft 6 increases.

Then, when the power generation motor torque Trqgen becomes zero, it is determined that the torque replacement is completed (timing T4), and the mode switching control is terminated after waiting for the clutch C2 to be released (timing T5). When the mode switching control is completed, the traveling motor 3 is stopped.

As a result, the total drive torque Trqtl is maintained constant before and after switching from the series hybrid mode HEV to the engine direct connection mode ENG. That is, when switching the traveling mode, it is possible to suppress a shock caused by torque fluctuation.

However, the actual engine torque aTrqeng generated by the engine 1 may deviate from the target engine torque tTrqeng depending on the state of the atmospheric temperature and humidity and the cooling water temperature.

FIG. 6 is a time chart when the mode switching control from the series hybrid mode HEV to the engine direct connection mode ENG is executed when the actual engine torque aTrqeng is smaller than the target engine torque tTrqeng.

This is the same as in FIG. 5 until the end of the clutch engagement phase (timing T3). However, in the torque replacement phase, since the power generation motor torque Trqgen is controlled on the premise that the target engine torque tTrqeng is generated, a deviation occurs in the total drive torque. Specifically, the actual total drive torque aTrqtl becomes smaller than the target total drive torque tTrqtl by the difference between the actual engine torque aTrqeng and the target engine torque tTrqeng (hereinafter, also referred to as the engine torque deviation amount). As a result, the total drive torque Trqtl changes between the start (timing T1) and the end (timing T5) of the mode switching control, and a shock occurs with the mode switching.

On the other hand, FIG. 7 is a time chart when the mode switching control from the series hybrid mode HEV to the engine direct connection mode ENG is executed when the actual engine torque aTrqeng is larger than the target engine torque tTrqeng.

This is the same as in FIG. 5 until the end of the clutch engagement phase (timing T3). However, in the torque replacement phase, since the power generation motor torque Trqgen is controlled on the premise that the target engine torque tTrqeng is generated, a deviation occurs in the total drive torque. Specifically, the actual total drive torque aTrqtl becomes larger than the target total drive torque tTrqtl by the amount of engine torque deviation. As a result, the total drive torque Trqtl changes between the start (timing T1) and the end (timing T5) of the mode switching control, and a shock occurs with the mode switching.

Therefore, in the present embodiment, even when there is a discrepancy between the actual engine torque aTrqeng and the target engine torque tTrqeng, the control described below is executed in order to suppress the shock due to the mode switching.

FIG. 8 is a flowchart showing the contents of control executed by the controller 101 in the torque replacement phase. The control is pre-programmed in the controller 101. Hereinafter, description will be given according to the steps in the flowchart.

In step S100, the controller 101 calculates the amount of engine torque deviation based on the target engine torque tTrqeng and the actual engine torque aTrqeng. The target engine torque tTrqeng can be calculated based on the target torque of the drive shaft 6 determined based on the accelerator opening APO and the vehicle speed VSP, and the gear ratio of the gear train Gc and the differential 5. The actual engine torque aTrqeng can be calculated based on the intake air amount detected by an air flow sensor (not shown), the ignition timing, and the friction of each part. The actual engine torque aTrqeng may be detected by providing a shaft torque sensor on the crankshaft 11. It is also possible to calculate the actual engine torque aTrqeng based on the comparison result between the generated torque Trqgen of the power generation motor 2 that receives the actual engine torque aTrqeng and generates power during the power generation in the series hybrid mode HEV and the target engine torque tTrqeng. ..

In step S101, the controller 101 determines whether or not the engine torque deviation amount is zero. If it is zero, the process of step S102 is executed, and if it is not zero, the process of step S103 is executed.

In step S102, the controller 101 ends this routine without correcting the target engine torque tTrqeng and the target power generation motor torque tTrqgen. This is because the above-mentioned problem does not occur if the engine torque deviation amount is zero.

In step S103, the controller 101 determines whether or not the engine torque deviation amount is greater than zero, executes the process of step S104 if it is greater than zero, and executes the process of step S106 if it is less than zero.

In step S104, the controller 101 determines whether or not the charged state of the battery 4 (hereinafter, also referred to as battery SOC) is higher than the threshold value α. Here, the battery SOC is represented by a percentage where the empty state is zero and the fully charged state is 100. The threshold value α is a lower limit value of the dischargeable battery SOC, and is a preset value based on the capacity of the battery 4, the power consumption of the in-vehicle auxiliary equipment, and the like. The battery SOC is calculated by the controller 101 based on the integrated value of the charge / discharge current of the battery 4 and the terminal voltage of the battery 4.

In step S104, the controller 101 executes the process of step S105 corresponding to the first correction method when the battery SOC is larger than the threshold value α, and steps S107 corresponding to the second correction method when the battery SOC is equal to or less than the threshold value α. Executes the processing of.

In step S105, the controller 101 corrects the target power generation motor torque tTrqgen by adding the engine torque deviation amount to the target power generation motor torque tTrqgen without changing the target engine torque tTrqeng. That is, if the battery SOC is larger than the threshold value α, there is a margin for powering the power generation motor 2, so the amount of engine torque deviation is compensated by powering the power generation motor 2 (that is, increasing the power generation motor torque). When correcting the target power generation motor torque tTrqgen, the engine torque deviation amount is converted into the power generation motor torque using the gear ratio of the gear train Gc.

On the other hand, when the engine torque deviation amount is zero or less, the controller 101 determines in step S106 whether the battery SOC is larger than the threshold value β, and if it is large, executes the process of step S107, and the battery SOC is equal to or less than the threshold value β. If so, the process of step S105 is executed. The threshold value β is an upper limit value of the rechargeable battery SOC, and is a preset value based on the capacity of the battery 4, the power consumption of the in-vehicle auxiliary equipment, and the like.

In step S105, which is executed when the engine torque deviation amount is larger than zero, the power generation motor 2 is driven, but in step S105, which is executed when the engine torque deviation amount is zero or less, power is generated even after the torque replacement phase ends. The motor 2 will generate electricity. That is, if the battery SOC is smaller than the threshold value β, there is a margin to charge the power generated by the power generation motor 2. Therefore, by using an excessive engine torque for the power generation of the power generation motor 2 with respect to the target engine torque tTrqeng, the engine torque shifts. Offset the amount.

In step S107, the controller 101 makes a correction by adding the engine torque deviation amount to the target engine torque tTrqeng without changing the target power generation motor torque tTrqgen. Step S107 is executed when the battery SOC is equal to or lower than the threshold value α or equal to or higher than the threshold value β, that is, when the battery SOC is out of the chargeable / dischargeable range. Therefore, since the power generation motor 2 cannot be powered or generated, the actual engine torque aTrqeng is changed by correcting the target engine torque tTrqeng, and thereby the deviation of the total drive torque Trqtl due to the engine torque deviation amount, that is, the mode. Eliminates torque steps before and after switching control.

9 to 12 are time charts when the flowchart of FIG. 8 is executed.

FIG. 9 is a time chart when the actual engine torque aTrqeng is smaller than the target engine torque tTrqeng and the battery SOC is larger than the threshold value α. This is the same as in FIG. 6 until the end of the clutch engagement phase (timing T3).

In the torque replacement phase, the slope of the change in the target power generation motor torque tTrqgen is larger than that in FIG. 6, and becomes a positive value in the middle of the torque replacement phase. That is, the power generation motor 2 is in the power running state from the middle of the torque replacement phase. This is because the engine torque deviation amount (positive value) is added to the target power generation motor torque tTrqgen by the process of step S105. Then, even after entering the engine direct connection mode, the power generation motor 2 continues power running. As a result, as shown in the figure, the total drive torque Trqttl becomes a constant value before and after the mode switching control.

FIG. 10 is a time chart when the actual engine torque aTrqeng is smaller than the target engine torque tTrqeng and the battery SOC is equal to or less than the threshold value α. This is the same as in FIG. 6 until the end of the clutch engagement phase (timing T3).

In the torque replacement phase, the target engine torque tTrqeng increases, and at the end of the torque replacement phase (timing T4), the actual engine torque aTrqeng becomes the target engine torque tTrqeng at the start of the torque replacement phase (timing T3). .. This is because the torque deviation amount (positive value) is added to the target engine torque tTrqeng by the process of step S107. Then, even after entering the engine direct connection mode, this target engine torque tTrqeng is maintained. As a result, as shown in the figure, the total drive torque becomes a constant value before and after the mode switching control.

FIG. 11 is a time chart when the actual engine torque aTrqeng is smaller than the target engine torque tTrqeng and the battery SOC is smaller than the threshold value β. This is the same as in FIG. 7 until the end of the clutch engagement phase (timing T3).

In the torque replacement phase, the slope of the change in the target power generation motor torque tTrqgen is smaller than that in FIG. 7, and is a negative value even at the end of the torque replacement phase (timing T4). That is, the power generation motor 2 is still generating power even after the torque replacement phase is completed. This is because the engine torque deviation amount (negative value) is added to the target power generation motor torque tTrqgen by the process of step S105. Then, even after entering the engine direct connection mode, the power generation motor 2 continues to generate power. As a result, as shown in the figure, the total drive torque Trqttl becomes a constant value before and after the mode switching control.

FIG. 12 is a time chart when the actual engine torque aTrqeng is smaller than the target engine torque tTrqeng and the battery SOC is equal to or less than the threshold value β. This is the same as in FIG. 7 until the end of the clutch engagement phase (timing T3).

In the torque replacement phase, the target engine torque tTrqeng decreases, and at the end of the torque replacement phase (timing T4), the actual engine torque aTrqeng becomes the target engine torque tTrqeng at the start of the torque replacement phase (timing T3). .. This is because the torque deviation amount (negative value) is added to the target engine torque tTrqeng by the process of step S107. Then, even after entering the engine direct connection mode, this target engine torque tTrqeng is maintained. As a result, as shown in the figure, the total drive torque Trqttl becomes a constant value before and after the mode switching control.

As described above, in the present embodiment, the deviation of the total drive torque Trqtl due to the amount of engine torque deviation is corrected by increasing or decreasing the target power generation motor torque tTrqgen or the target engine torque tTrqeng, and the torque fluctuation before and after the mode switching control is performed. Suppress.

From the viewpoint of control accuracy, a correction (first correction method) for increasing or decreasing the power generation torque of the power generation motor 2 is preferable. However, the power generation motor 2 can be powered only when the battery SOC is larger than the threshold value α, that is, the battery 4 has a sufficient power margin to power the power generation motor 2. Further, the power generation motor 2 can generate power only when the battery SOC is smaller than the threshold value β, that is, when there is enough power to charge the generated power. Therefore, in the present embodiment, when the battery 4 has a power margin, the first correction method using the power generation motor 2 is selected and executed, and when there is no margin, the second correction method using the engine 1 is selected and executed. Execute.

By the way, in the control shown in FIG. 8, it is determined whether the engine torque deviation amount is positive or negative (S103), and different processes (S104, S105) are performed according to the determination result. However, even if the control shown in FIG. 8 is modified as described below, it is possible to suppress a change in torque before and after the mode switching control due to the amount of engine torque deviation.

(Modification example)
FIG. 13 is a flowchart showing the content of control of the torque application phase according to the modified example. The modified example is also included in the scope of the present invention as in the first embodiment described above.

Since steps S200 to S202 are the same as steps S100 to S102 in FIG. 8, description thereof will be omitted.

When the controller 101 determines in step S201 that the engine torque deviation amount is not zero, the controller 101 determines in step S203 whether or not the battery SOC is larger than the threshold value α. The processing content of step S203 is the same as that of step S104 of FIG.

Then, the controller 101 executes the process of step S204 when the battery SOC is larger than the threshold value α, and executes the process of step S206 when the battery SOC is equal to or less than the threshold value α. The processing content of step S206 is the same as that of step S107 of FIG.

In step S204, the controller 101 determines whether or not the battery SOC is smaller than the threshold value β, and if it is smaller, executes the process of step S205, and if not, executes the process of step S206. The processing content of step S205 is the same as that of step S105 of FIG.

As described above, in this modification, it is determined whether to correct the target power generation motor torque tTrqgen or the target engine torque tTrqeng only within the range of the battery SOC, regardless of whether the engine torque deviation amount is positive or negative.

According to this modification, if the battery SOC is within the chargeable / dischargeable range (threshold α <battery SOC <threshold β), the first correction method is adopted, and if it is outside the range, the second correction method is adopted. It will be. Therefore, if the engine torque deviation amount is positive, the first correction method can be adopted for the battery SOC> threshold β, and if the engine torque deviation amount is negative, the first correction method can be adopted for the battery SOC <threshold value α. Even in this case, the second correction method is adopted. That is, even when the first correction method having higher control accuracy can be adopted, the second correction method may be adopted. However, the second correction method is not selected when the second correction method cannot be executed. Further, since the correction method is selected by the same processing regardless of whether the engine torque deviation amount is positive or negative, the calculation load can be reduced.

As described above, the electric vehicle of the present embodiment can be driven by the internal combustion engine 1, the power generation motor 2 arranged so as to generate power by receiving the power of the internal combustion engine 1, and the electric power generated by the power generation motor 2. The traveling motor 3 provided is provided. Further, the electric vehicle has a series hybrid mode HEV in which the internal combustion engine 1 and the drive wheels 7 are connected to each other via the first clutch C1 so as to be disconnected and disconnected, and the power of the traveling motor 3 is transmitted to the drive wheels 7 to travel. The power of the internal combustion engine 1 and the power of the power generation motor are transmitted to the drive wheels 7 to travel, and the engine direct connection mode ENG can be switched.

The controller 101 releases the first clutch C1 in the series hybrid mode HEV, and engages the first clutch C1 in the engine direct connection mode ENG. Then, the controller 101 transmits to the drive wheels 7 due to the difference between the target torque and the actual torque of the internal combustion engine 1 when switching from the series hybrid mode HEV to the engine direct connection mode ENG and when traveling in the engine direct connection mode ENG. The first correction method for correcting the deviation of the total drive torque to be performed by increasing or decreasing the torque of the power generation motor 2, and the second correction method for correcting the deviation of the total drive torque by increasing or decreasing the actual torque of the internal combustion engine 1. Is selected and executed based on the battery SOC (battery charge state).

With the above control, it is possible to eliminate a step in the total drive torque Trqtl when switching from the series hybrid mode HEV to the engine direct connection mode ENG.

In the present embodiment, the first correction method is selected when the battery SOC is within a predetermined range in which charging and discharging are possible, and the second correction method is selected when the battery SOC is outside the predetermined range. As a result, the battery 4 will not be overcharged or overdischarged when the second correction method is executed.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. 14 to 20.

FIG. 14 is a time chart when switching from the engine direct connection mode ENG to the series hybrid mode HEV.

As shown in FIG. 14, the engine direct connection mode ENG is switched to the series hybrid mode HEV after a mode switching period. The mode switching period includes a rotation synchronization phase, a clutch engagement phase, a torque replacement phase, and a clutch release phase.

When a request for switching to the series hybrid mode HEV occurs at the timing T1 during running in the engine direct connection mode ENG, the rotation synchronization phase is started. In the rotation synchronization phase, the traveling motor rotation speed Nmg is increased by controlling the torque Trqmg of the traveling motor 3 to approach the output rotation speed Nout corresponding to the rotation speed of the drive shaft 6. The traveling motor rotation speed Nmg referred to here is a conversion of the engine rotation speed Neng into the rotation speed of the traveling motor 3 based on the gear ratio of the gear train Gc. When the difference between the output rotation speed Nout and the traveling motor rotation speed Nmg decreases to a predetermined value, or the difference in rotation speed is equal to or less than a predetermined value continues for a predetermined time (timing T2). Assuming that the rotation synchronization is completed, the process shifts to the clutch engagement phase and the clutch C2 is engaged. When the engagement of the clutch C2 is completed (timing T3), the torque replacement phase is started. Here, the state in which the clutch C1 which is the clutch on the release side is engaged is maintained from the rotation synchronization phase to the clutch engagement phase, and in the torque replacement phase, a state in which both the clutches C1 and C2 are engaged is formed. Then, in the present embodiment, a command for releasing the clutch C1 is output at the same time as the transition to the torque replacement phase (timing T3). However, the clutch C1 maintains the engaged state until the total of the engine torque Trqeng and the power generation motor torque Trqgen becomes zero.

In the torque replacement phase, the power generation motor torque Trqgen is decreased while the traveling motor torque Trqmg is increased so that the torque applied to the drive shaft 6, that is, the total drive torque Trqtl of the vehicle is kept constant. At this time, the engine torque Trqeng is maintained constant. That is, as the power generation motor torque Trqgen decreases, the engine torque Trqeng transmitted to the drive shaft 6 increases.

Then, it is determined that the torque replacement is completed when the traveling motor torque Trqmg becomes the engine torque Trqeng before the mode switching control starts (timing T4), and the mode switching control is terminated after waiting for the clutch C1 to be released. (Timing T5).

As a result, the total drive torque Trqtl is maintained constant before and after switching from the engine direct connection mode ENG to the series hybrid mode HEV. That is, when switching the traveling mode, it is possible to suppress a shock caused by torque fluctuation.

However, as in the case of switching from the series hybrid mode HEV to the engine direct connection mode ENG, if there is an engine torque deviation amount, the torque fluctuates before and after the mode switching control, and a shock occurs due to this.

Therefore, in the present embodiment, even when there is an engine torque deviation amount, the control described below is executed in order to suppress the shock caused by the mode switching.

FIG. 15 is a flowchart showing the contents of the control executed by the controller 101 in the torque replacement phase of the mode switching control from the engine direct connection mode ENG to the series hybrid mode HEV.

The control is pre-programmed in the controller 101. Hereinafter, description will be given according to the steps in the flowchart.

Since steps S300 to S302 are the same as steps S100 to S102 in FIG. 8, description thereof will be omitted.

In step S303, the controller 101 determines whether or not the correction is performed by the power generation motor torque Trqgen, that is, whether or not the first correction method is being executed while traveling in the engine direct connection mode ENG. If the determination result is positive (yes), the controller 101 executes the process of step S304, and if the determination result is negative (no), the controller 101 executes the process of step S305.

In step S304, the controller 101 stops or prohibits the correction of the target engine torque tTrqeng. That is, when the positive determination is made in step S303 and the processing in step S304 is performed, the difference between the target engine torque tTequeng and the actual engine torque aTrqeng is not corrected even after that because the second correction method is not originally performed. On the other hand, when a positive determination is made in step S306 described later and the process of step S304 is performed, the second correction method that has been performed up to that point is stopped. In either case, since the difference between the target engine torque tTequeng and the actual engine torque aTrqeng is not corrected after the transition to the series hybrid mode HEV, the generated torque of the power generation motor 2 after the transition to the series hybrid mode HEV is deviated. It is a value corresponding to the actual engine torque aTrqeng.

In step S305, the controller 101 determines whether or not the engine torque deviation amount is greater than zero. The determination is the same as in step S103 of FIG.

If the determination result is positive (yes), the controller 101 executes the process of step S306, and if the determination result is negative (no), the controller 101 executes the process of step S308.

In step S306, the controller 101 determines whether or not the battery SOC is larger than the threshold value β. The determination is the same as in step S106 of FIG. If the determination result is positive (yes), the controller 101 executes the process of step S304 described above, and if the determination result is negative (no), executes the process of step S307.

The reason why the correction of the target engine torque tTrqeng (second correction method) is stopped in step S304 when the determination result in step S306 is positive (yes) is as follows. When the correction of the target engine torque tTrqeng is stopped, the actual torque of the internal combustion engine 1 decreases, and the torque of the power generation motor 2 also decreases accordingly, so that the generated power decreases. In a situation where the battery SOC is higher than the threshold β, it is desirable to reduce the generated power. Further, when the engine direct connection mode ENG is entered again after the processing of step S304, there is a high possibility that the first correction method for correcting the target power generation motor torque tTrqgen will be executed. Therefore, in the series hybrid mode HEV. It is desirable to stop the second correction method. Therefore, the second correction method is stopped.

In step S307, the controller 101 continues to correct the target engine torque tTrqeng (second correction method). That is, the fact that a negative determination result is obtained in step S303 means that the second correction method was performed in the engine direct connection mode ENG, and this is continued in step S307. In this case, the torque of the power generation motor 2 after the transition to the series hybrid mode HEV becomes a value corresponding to the corrected actual engine torque aTrqeng.

The reason for continuing the second correction method in step S307 is as follows. If the second correction method is stopped in step S307, the amount of engine torque deviation is positive, so that the actual torque of the internal combustion engine 1 decreases. In this case, the generated torque of the power generation motor 2 also decreases, so that the generated power decreases. In situations where the battery SOC is below the threshold β, the generated power should not be reduced. Therefore, the second correction method is continued.

In step S308, the controller 101 determines whether or not the battery SOC is greater than the threshold value α. The determination is the same as in step S104 of FIG. The controller 101 executes the process of step S309 when the determination result is positive (yes), and executes the process of step S310 when the determination result is negative (no).

In step S309, the controller 101 continues the correction (second correction method) of the target engine torque tTrqeng as in step S307. In this case, the torque of the power generation motor 2 after the transition to the series hybrid mode HEV becomes a value corresponding to the corrected actual engine torque aTrqeng. The reason for continuing the second correction method is as follows. If the second correction method is stopped, the amount of engine torque deviation is negative, so that the actual torque of the internal combustion engine 1 increases. In this case, the torque of the power generation motor 2 also increases, so that the generated power increases, but when the battery SOC is higher than the threshold α, it is not necessary to increase the generated power. Therefore, the second correction method is continued.

In step S310, the controller 101 stops the correction (second correction method) of the target engine torque tTrqeng. In this case, the torque of the power generation motor 2 becomes a value corresponding to the uncorrected target engine torque tTrqeng. The reason for stopping the second correction method is as follows. When the second correction method is stopped, the amount of engine torque deviation is negative, so that the actual torque of the internal combustion engine 1 increases. In this case, the torque of the power generation motor 2 also increases, so that the generated power increases, but in a situation where the battery SOC is lower than the threshold α, it is desirable to increase the generated power. Therefore, the second correction method is stopped.

16 to 20 are time charts when the above control is executed.

FIG. 16 is a time chart when the engine torque deviation amount is not zero and the first correction method is executed in the engine direct connection mode ENG, that is, when step S303 executes S304 in yes. It is the same as in FIG. 14 except that the target power generation motor torque tTrqgen is corrected until the end of the clutch engagement phase (timing T3).

In the torque replacement phase, the second correction method is prohibited, and the torque of the power generation motor 2 becomes a value corresponding to the actual engine torque aTrqeng (S304). As a result, the power generation motor torque Trqgen after the torque replacement phase becomes a value larger than the power generation motor torque Trqgen in FIG. That is, the torque amount corrected by the first correction method in the engine direct connection mode ENG is restored by the power generation motor torque Trqgen of the power generation motor 2.

Further, the target traveling motor torque tTrqmg rises to the target engine torque tTrqeng at the timing T4. By the above control, the total drive torque Trqtl is maintained constant before and after the mode switching control.

FIG. 17 is a time chart when the second correction method is executed in the engine direct connection mode ENG, the engine torque deviation amount is larger than zero, and the battery SOC is equal to or less than the threshold value β, that is, when step S307 is executed. It is the same as in FIG. 14 except that the target engine torque tTrqeng is corrected until the end of the clutch engagement phase (timing T3).

The target engine torque tTrqeng and the actual engine torque aTrqeng in the figure are values after correction by the second correction method. That is, the actual engine torque aTrqeng in the figure is the target engine torque tTrqeng before the correction by the second correction method. In other words, the target engine torque tTrqeng is corrected by the second correction method so that the actual engine torque aTrqeng has the same magnitude as the target engine torque tTrqeng before correction.

Since the second correction method is continued even after the torque replacement phase, the target traveling motor torque tTrqmg increases to the actual engine torque aTrqeng at the timing T4. By the above control, the total drive torque Trqtl is maintained constant before and after the mode switching control. Further, the power generation motor 2 generates electric power corresponding to the corrected actual engine torque aTrqeng.

FIG. 18 shows a case where the second correction method is executed in the engine direct connection mode ENG, the engine torque deviation amount is larger than zero, and the battery SOC is larger than the threshold value β, that is, the step S306 executes step S304 in yes. It is a time chart of. This is the same as in FIG. 17 until the end of the clutch engagement phase (timing T3).

The target engine torque tTrqeng and the actual engine torque aTrqeng before the timing T3 in the figure are the values after the correction by the second correction method. That is, the actual engine torque aTrqeng before the timing T3 is the target engine torque tTrqeng before the correction by the second correction method.

In the torque replacement phase, the target engine torque tTrqeng is reduced to the value before the correction by the second correction method by stopping the second correction method. Along with this, the actual engine torque aTrqeng also decreases. Then, the target power generation motor torque tTrqgen becomes a value corresponding to the uncorrected target engine torque tTrqgen. On the other hand, the target running motor torque tTrqmg increases until it becomes the same as the target engine torque tTrqeng before correction. By the above control, the total drive torque Trqtl is maintained constant before and after the mode switching control. Further, the power generation motor 2 generates electric power according to the target engine torque tTrqeng at the timing T4.

FIG. 19 is a time chart when the second correction method is executed in the engine direct connection mode ENG, the engine torque deviation amount is smaller than zero, and the battery SOC is smaller than the threshold value α, that is, when step S310 is executed. .. It is the same as in FIG. 14 except that the target engine torque tTrqeng is corrected until the end of the clutch engagement phase (timing T3). The target engine torque tTrqeng and the actual engine torque aTrqeng before the timing T3 in the figure are the values after the correction by the second correction method. That is, the actual engine torque aTrqeng before the timing T3 is the target engine torque tTrqeng before the correction by the second correction method.

In the torque replacement phase, the target engine torque tTrqeng is increased to the value before the correction by the second correction method by stopping the second correction method. Along with this, the actual engine torque aTrqeng also increases. Then, the target power generation motor torque tTrqgen becomes a value corresponding to the uncorrected target engine torque tTrqgen. On the other hand, the target running motor torque tTrqmg increases until it becomes the same as the target engine torque tTrqeng before correction. By the above control, the total drive torque Trqtl is maintained constant before and after the mode switching control. Further, the power generation motor 2 generates electric power according to the target engine torque tTrqeng at the timing T4.

FIG. 20 is a time chart when the second correction method is executed in the engine direct connection mode ENG, the engine torque deviation amount is smaller than zero, and the battery SOC is larger than the threshold value α, that is, when step S309 is executed. .. It is the same as in FIG. 14 except that the target engine torque tTrqeng is corrected until the end of the clutch engagement phase (timing T3). The target engine torque tTrqeng and the actual engine torque aTrqeng before the timing T3 in the figure are the values after the correction by the second correction method. That is, the actual engine torque aTrqeng before the timing T3 is the target engine torque tTrqeng before the correction by the second correction method.

Since the second correction method is continued even after the torque replacement phase, the target traveling motor torque tTrqmg increases to the actual engine torque aTrqeng at the timing T4. By the above control, the total drive torque Trqtl is maintained constant before and after the mode switching control. Further, the power generation motor 2 generates electric power according to the actual engine torque aTrqeng at the timing T4.

As described above, in the present embodiment, when the first correction method is executed when the engine direct connection mode ENG is switched to the series hybrid mode HEV and the engine is running in the engine direct connection mode ENG before the switching, after the switching. The correction of the difference between the target engine torque tTequeng and the actual engine torque aTrqeng in the series hybrid mode HEV is stopped. That is, when the first correction method is executed in the engine direct connection mode ENG, the power generation motor 2 generates electric power corresponding to the actual engine torque aTrqeng after the torque replacement phase, thereby correcting the torque in the engine direct connection mode ENG. Restore the amount. As a result, the accuracy can be improved as compared with the case where the torque correction amount is restored by the torque control of the engine 1.

It goes without saying that the present invention is not limited to the above-described embodiment, and various changes can be made within the scope of the technical idea described in the claims.

1 Internal combustion engine 2 Power generation motor 3 Traveling motor 4 Battery 7 Drive wheels

Claims (4)

With an internal combustion engine
A power generation motor arranged so as to be able to generate power by receiving the power of the internal combustion engine,
A traveling motor that can be driven by the electric power generated by the power generation motor,
With
A series hybrid mode in which the internal combustion engine and the drive wheels are connectably connected via a first clutch and the power of the traveling motor is transmitted to the drive wheels to travel, and the power of the internal combustion engine and the power generation motor. It is a control method of an electric vehicle configured to be able to switch between an engine direct connection mode in which the vehicle travels by transmitting the power of the above to the drive wheels.
In the series hybrid mode, the first clutch is released and
In the engine direct connection mode, the first clutch is engaged and
When switching from the series hybrid mode to the engine direct connection mode, and when driving in the engine direct connection mode,
The first correction method for correcting the deviation of the total drive torque transmitted to the drive wheels due to the difference between the target torque of the internal combustion engine and the actual torque by increasing or decreasing the actual torque of the power generation motor, and the total. A control method for an electric vehicle, characterized in that any one of the second correction methods for correcting the deviation of the drive torque by increasing or decreasing the torque of the internal combustion engine is selected and executed based on the battery charge state. In the method for controlling an electric vehicle according to claim 1,
A control method for an electric vehicle, in which the first correction method is selected when the battery charging state is within a predetermined range in which charging and discharging are possible, and the second correction method is selected when the battery charging state is outside the predetermined range. .. In the method for controlling an electric vehicle according to claim 1,
When switching from the engine direct connection mode to the series hybrid mode,
When the first correction method is executed during running in the engine direct connection mode before switching, the difference between the target torque and the actual torque of the internal combustion engine is corrected in the series hybrid mode after switching. How to control an electric vehicle to stop. With an internal combustion engine
A power generation motor arranged so as to be able to generate power by receiving the power of the internal combustion engine,
A traveling motor that can be driven by the electric power generated by the power generation motor,
A control unit that controls the internal combustion engine, the power generation motor, and the traveling motor.
With
A series hybrid mode in which the internal combustion engine and the drive wheels are connected to each other via a first clutch so that the power of the traveling motor is transmitted to the drive wheels to travel, and the power of the internal combustion engine is transmitted to the drive wheels. It is a drive system of an electric vehicle that is configured to be able to switch between the engine direct connection mode that runs by transmitting to the engine.
The control unit
In the series hybrid mode, the first clutch is released and
In the engine direct connection mode, the first clutch is engaged and
When switching from the series hybrid mode to the engine direct connection mode, and when driving in the engine direct connection mode,
The first correction method for correcting the deviation of the total drive torque transmitted to the drive wheels due to the difference between the target torque and the actual torque of the internal combustion engine by increasing or decreasing the torque of the power generation motor.
It is characterized in that it is programmed to select and execute one of the second correction methods for correcting the deviation of the total drive torque by increasing or decreasing the torque of the internal combustion engine based on the battery charge state. , Electric vehicle drive system.

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