JP2013132166A - Control device of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an electric vehicle which can obtain acceleration performance corresponding to an acceleration requirement of a driver.SOLUTION: A vehicle controller 111 generates a coast traveling state by operating a friction brake and a motor 100 until an acceleration operation is detected by an acceleration stroke sensor 111b after it is detected that a brake operation state is changed to a non-operation state from an operation state by a brake stroke sensor 111a.

Description

  The present invention relates to a control device for an electric vehicle.

  In Patent Document 1, when it is determined that the effective torque obtained by subtracting the drag torque from the motor torque enters or exits the zero torque section of the gear backlash mechanism, the effective torque is parabolic or exponential while initializing the control time. A technique for reducing gear backlash vibration by limiting to a functional form of torque is disclosed.

JP 2010-215213 JP

However, the conventional technology has a problem that the acceleration performance according to the driver's acceleration request cannot be obtained because the torque is limited for a predetermined time.
The objective of this invention is providing the control apparatus of the electric vehicle which can implement | achieve the acceleration performance according to the driver | operator's acceleration request.

  In the control apparatus for an electric vehicle according to the present invention, the braking force generation unit and the electric motor are operated during a period from when it is detected that the brake operation state is changed from the operation state to the non-operation state until the accelerator operation is detected. To generate a coasting condition.

  Therefore, the control device for an electric vehicle according to the present invention can realize acceleration performance according to the driver's acceleration request.

1 is a system configuration diagram of an electric vehicle according to Embodiment 1. FIG. 3 is a block diagram of a braking / driving torque command value calculation control of a vehicle controller 111. FIG. FIG. 5 is a block diagram of a motor torque command reference value calculation control of a motor torque command value calculation unit 200 by an accelerator. 6 is a control block diagram of regenerative friction brake distribution of regenerative friction brake distribution unit 202. FIG. 7 is a flowchart showing a flow of torque command lower limit value calculation control processing by a motor torque command lower limit value calculation unit 204. FIG. 10 is a block diagram of a motor torque command value calculation control of a backlash vibration suppression torque command value change amount limiting unit 207 when zero torque is passed. It is a torque change amount limit value calculation map. It is a time chart which shows the gear backlash vibration suppression effect | action at the time of implementing only the backlash vibration suppression torque command value variation | change_quantity limitation control of Example 1. FIG. 3 is a time chart showing an effect of improving torque response by the brake cooperative control of the first embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the control apparatus of the electric vehicle of this invention is demonstrated based on the Example shown on drawing.
[Example 1]
First, the configuration will be described.
FIG. 1 is a system configuration diagram of an electric vehicle according to a first embodiment.
The electric vehicle according to the first embodiment includes an electric motor (hereinafter referred to as a motor) 100 that generates positive and negative torques (drive torque and braking torque). A resolver is connected to the motor 100 as the rotation sensor 101, and the motor controller 102 outputs a drive signal to the inverter 103 with reference to information of the rotation sensor 101. The inverter 103 supplies a current corresponding to the drive signal to the motor 100 and controls the motor torque.
An output shaft 100a of the motor 100 is connected to a speed reducer (gear transmission mechanism) 104, and transmits torque to the axle 106 via a differential gear (gear transmission mechanism) 105. Electric power for driving the motor 100 is supplied from the high voltage battery 107. The high voltage battery 107 is monitored by a battery controller 108 for the state of charge and the degree of heat generation. A DC-DC converter 109 is connected to the high voltage battery 107, and the voltage is stepped down by the DC-DC converter 109 to charge the low voltage battery 110.
The vehicle controller (control unit) 111 monitors the strokes (operation amounts) of the brake pedal and accelerator pedal (not shown) by a brake stroke sensor (brake operation state detection unit) 111a and an accelerator stroke sensor (acceleration operation state detection unit) 111b. Thus, a positive or negative torque command corresponding to the stroke is transmitted to the braking control device 113 via the in-vehicle communication line 112.

The braking control device 113 prevents driving slip from each wheel speed information from each wheel speed sensor 114a, 114b, 114c, 114d provided on each wheel FL, FR, RL, RR and motor torque information output from the motor controller 102. Torque control such as control (TCS control) and braking slip prevention control (ABS control) is performed.
When the brake control device 113 controls the friction brake torque, each wheel FL, FR, RL, RR is operated through the hydraulic pipe 115 by operating a pump (not shown) in the brake control device 113 according to the pedaling force of the driver. Brake fluid is sent to each of the brake calipers 116a, 116b, 116c, 116d provided in the motor to generate a friction brake torque. On the other hand, when controlling the motor torque, a torque command is given to the motor controller 102 via the in-vehicle communication line 112.
The brake control device 113 and the brake calipers 116a, 116b, 116c, and 116d constitute a friction brake (braking force generation unit) that applies a braking force to the wheels FL, FR, RL, and RR.

FIG. 2 is a block diagram of the braking / driving torque command value calculation control of the vehicle controller 111. The control block 111c shown in FIG. 2 is a friction brake between the time when the brake stroke state is detected by the brake stroke sensor 111a and the time when the accelerator stroke is detected by the accelerator stroke sensor 111b. And the motor 100 is operated to generate a coast running state.
The accelerator motor torque command value calculation unit 200 calculates a motor torque command reference value based on the accelerator operation amount, the vehicle speed, and the shift position. FIG. 3 is a block diagram of the motor torque command reference value calculation control of the motor torque command value calculation unit 200 by the accelerator. The motor torque command reference value increases the drive torque as the accelerator operation amount increases or the vehicle speed decreases. In addition, when the accelerator operation amount is zero, the driving torque decreases as the vehicle speed decreases in order to simulate the creep torque of an automatic transmission vehicle when the vehicle speed is at a predetermined speed (for example, 5 km / h) or less and in a low speed region. In a speed region where the vehicle speed exceeds the predetermined speed, regenerative brake torque is applied to simulate engine brake torque in a coasting state. Note that the reverse occurs when the shift position is reverse. The motor torque command reference value for the accelerator operation and according to the motor rotation speed is set in advance as a map for each shift position and each travel mode (sport mode, eco mode, etc.).
Axle torque command value calculation unit 201 by brake calculates a friction brake torque command reference value based on the brake operation amount. The friction brake torque command reference value increases the braking torque as the brake operation amount increases.

The regenerative friction brake distribution unit 202 distributes the friction brake torque command reference value to the braking force command friction brake torque component and the braking force command motor torque component based on the vehicle speed. FIG. 4 is a control block diagram of the regenerative friction brake distribution of the regenerative friction brake distribution unit 202. The friction brake torque command reference value is compared with the motor torque limit value according to the vehicle speed, and the larger value, that is, absolute The smaller value is defined as a braking force command motor torque component, and a value obtained by subtracting the braking force command motor torque component from the friction brake torque command reference value is defined as a braking force command friction brake torque component. The motor torque limit value corresponding to the vehicle speed is the maximum regenerative torque that can be generated by the motor 100. Here, the maximum regenerative torque can be calculated from the vehicle body speed, the battery SOC of the high voltage battery 107, and the like. For example, the maximum regenerative torque is set to zero in a stop, a low speed region, and a high speed region where the inverter 103 is overloaded, which are regions where regeneration is impossible.
The driver request motor torque calculation unit 203 calculates the driver request motor torque by adding the braking force command motor torque component to the motor torque command reference value.

The motor torque command lower limit calculation unit 204 calculates the torque command lower limit value based on the driver request motor torque, the brake temperature, the shift position, the brake operation amount, and the motor torque command value. FIG. 5 is a flowchart showing a flow of torque command lower limit value calculation control processing by the motor torque command lower limit value calculation unit 204, and each step will be described below.
In step S501, if the sport mode is selected as the travel mode, the process proceeds to step S502, and if any other mode is selected, the process proceeds to step S506.
In step S502, if the brake is not in a high temperature state, the process proceeds to step S503, and if the brake is in a high temperature state, the process proceeds to step S506.
In step S503, if the brake operation is not performed, the process proceeds to step S504, and if the brake operation is performed, the process proceeds to step S506.
In step S504, if the motor torque command value is less than the predetermined value, the process proceeds to step S505, and if the torque command value is greater than the predetermined value, the process proceeds to step S506.
In step S505, the value obtained by adding the predetermined torque change amount to the previous value of the motor torque command (torque command value in the previous control cycle) is compared with the predetermined torque value (drive torque), and the smaller value is determined as the torque command lower limit value. To do.
In step S506, the driver request motor torque is compared with the minimum torque that can be output, and the larger value is set as the torque command lower limit value.

The motor torque selection unit 205 compares the driver request motor torque with the torque command lower limit value, and outputs the larger value as the motor torque command value after the lower limit value is limited.
The motor torque comparison unit 206 subtracts the motor torque command value after the lower limit restriction from the driver request motor torque.
The backlash vibration suppression torque command value change amount restriction unit (motor torque change amount restriction control unit) 207 normally outputs the motor torque command value after the lower limit value restriction as it is as the motor torque command value. When the zero torque passing through the zero torque section of the backlash mechanism or passing through the zero torque section is passed, the motor torque command value and the motor torque command value after the lower limit limit are input, and the motor torque is based on the logic as shown below Calculate the command value.
FIG. 6 is a block diagram of the motor torque command value calculation control of the backlash vibration suppression torque command value change amount limiting unit 207 when zero torque passes. In the block of FIG. 6, “Abs” outputs an absolute value of the input, and “Sign” outputs a sign signal (positive = 1, negative = −1). “Min” outputs the smaller value of the input, and “1 / Z” stores the value one control cycle before. That is, the backlash vibration suppression torque command value change amount limiting unit 207 determines the difference between the motor torque command value after the lower limit value limit and the motor torque command previous value, that is, the upper limit of the increase amount of torque per unit time. The torque change amount limit value calculated from the map shown in FIG. 6 is used to limit the value, and the value is added to the previous value of the motor torque command to obtain a torque command value. The map of FIG. 7 is a two-dimensional map, and the absolute value of the difference between the torque command absolute value (the absolute value of the previous value of the motor torque command) and the torque deviation (the motor torque command value after limiting the lower limit value and the previous value of the motor torque command). ). At this time, the calculated torque change amount limit value is set smaller as the torque command absolute value is smaller, and smaller as the torque deviation is smaller.
The calculated motor torque command value is sent to the motor controller 102 via the in-vehicle communication line 112.
The friction brake torque command value calculation unit 208 calculates a friction brake torque command value by adding a value obtained by subtracting the lower limit value motor torque command value from the driver request motor torque to the braking force command friction brake torque component.
The calculated friction brake torque command value is sent to the braking control device 113 via the in-vehicle communication line 112.

Next, the operation will be described.
[Gear backlash vibration suppression action]
FIG. 8 assumes a configuration in which the motor torque command lower limit value calculation unit 204, the motor torque selection unit 205, the motor torque comparison unit 206, and the friction brake torque command value calculation unit 208 are excluded from FIG. 2 as a comparative example of the first embodiment. 8 is a time chart when only backlash vibration suppression torque command value change amount limiting control by the backlash vibration suppression torque command value change amount limiting unit 207 is performed. In this comparative example, the driver requested motor torque is input to the backlash vibration suppression torque command value change amount limiting unit 207, and the braking force command friction brake torque component becomes the friction brake torque command value as it is.
As shown in FIG. 8, in the comparative example, when the accelerator pedal is operated again and turned to acceleration from the braking torque equivalent to the engine brake generated when the accelerator pedal is released during vehicle traveling, that is, when driving torque is requested, The increase amount per unit time of the motor torque is limited by the torque change amount limit value corresponding to the accelerator operation amount. Therefore, compared to the case without the torque change amount limiting control, the torque change amount when the zero torque passes (torque increase gradient) can be suppressed to be small, so that the gear backlash vibration can be reduced.

At this time, in the backlash vibration suppression torque command value change amount limiting control according to the first embodiment, when the torque increase gradient requested by the driver is large and the accelerator pedal depression amount is large, the torque according to the map shown in FIG. Since a large value is selected as the change amount limit value, the torque increase gradient becomes larger than when the accelerator pedal is gently operated. That is, when the driver intends to accelerate rapidly, the delay time with respect to the driver's acceleration request can be shortened instead of reducing the reduction effect of the gear backlash vibration. At this time, gear backlash vibration is generated, but the driver is not feeling uncomfortable because of rapid acceleration.
On the other hand, if the torque increase gradient required by the driver is small, the torque deviation of the map input shown in FIG. 7 does not increase, and the torque change amount limit value decreases. Thus, when the driver desires gentle acceleration, zero torque is passed with a small amount of change, so that the effect of suppressing gear backlash vibration can be sufficiently obtained.

[Torque response improvement]
By implementing the backlash vibration suppression torque command value variation limit control as described above, it is possible to achieve both the torque response that matches the acceleration request and the effect of suppressing the gear backlash vibration. There is always a delay in the response of the motor 100 to the operation. In particular, when the driver selects the sport mode as the travel mode, if the torque responsiveness to the accelerator operation is poor, the acceleration performance according to the driver's acceleration request cannot be obtained, giving a sense of incongruity.
On the other hand, in the first embodiment, when the sport mode is selected, the friction brake is operated after the change from the state with the brake operation to the state without the brake operation until the accelerator operation is detected. Then, the brake cooperative control is performed to generate a coasting state, that is, a braking torque corresponding to the engine brake.
As a result, it is not necessary to generate a braking torque equivalent to the engine brake by the regenerative braking torque of the motor 100, so that the motor torque is shifted from the braking torque to the driving torque and the zero torque is passed before the driver starts the accelerator operation. I can keep it. Therefore, since it is not necessary to limit the amount of torque change during the accelerator operation, the driving torque of the motor 100 can follow the accelerator operation without delay.
It should be noted that the brake cooperative control is not performed when a travel mode other than the sport mode that requires high acceleration performance is selected. This is because in the brake cooperative control, instead of simulating the engine brake torque by the normal regenerative brake torque, the engine brake torque by the friction brake is simulated, so that the regenerative efficiency during coasting decreases.

FIG. 9 is a time chart illustrating the torque response improvement effect by the brake cooperative control of the first embodiment. It is assumed that the sport mode is selected as the travel mode.
At time t1, since the state with the brake operation is shifted to the state without the brake operation, the flow from S501 → S502 → S503 → S506 is switched to the flow S501 → S502 → S503 → S504 → S505 in the flowchart of FIG. The motor torque command value is a value obtained by adding a predetermined torque change amount to the previous value of the motor torque command. Further, since the driver-requested motor torque is a braking torque equivalent to the engine brake, the friction brake torque command value is a value obtained by subtracting the torque command lower limit value from the braking torque equivalent to the engine brake.
In the period from time t1 to t2, the motor torque gradually increases (approaches zero) along the torque command lower limit value, so that the axle torque approaches a braking torque equivalent to the engine brake.
At time t2, the axle torque acting on the wheels becomes a braking torque equivalent to engine braking.
In the period from time t2 to t3, the friction brake torque gradually increases as the motor torque increases, so the axle torque is maintained at the braking torque equivalent to the engine brake. Note that when the motor torque (effective torque) enters the zero torque section of the gear backlash mechanism in the section from time t2 to t3, the backlash vibration suppression torque command value change limit control is activated, so the motor torque command value The amount of change per unit time is limited to be smaller than the predetermined torque change amount.

At time t3, the motor torque passes through zero torque, but since the amount of change in motor torque per unit time is limited, the gear backlash vibration can be reduced to a level that does not give the driver a sense of incongruity.
During the period from time t3 to t4, when the motor torque escapes from the zero torque section of the gear lash crush mechanism, the backlash vibration suppression torque command value change limit control is deactivated.
At time t5, since the driver has started the accelerator operation, in the flowchart of FIG. 5, the flow from S501 → S502 → S503 → S504 → S505 is switched to the flow S501 → S502 → S503, and the motor torque command value is changed to the accelerator operation. The corresponding driver request motor torque is obtained. Further, since the brake pedal is not operated, the friction brake torque command value becomes zero.
In the period from the time point t5 to the time point t6, the friction brake torque is zero, and the motor torque increases with the same gradient as the driver-requested motor torque according to the accelerator operation. Therefore, the axle torque increases with substantially the same gradient as the motor torque.

Here, in the comparative example, since the amount of change is limited when zero torque passes, the motor torque response to the accelerator operation is poor, and the acceleration performance according to the driver's acceleration request was not obtained. In Example 1, since zero torque is passed before the driver's accelerator operation, there is no need to limit the amount of torque change during the driver's accelerator operation, and acceleration performance according to the driver's acceleration request can be realized.
Further, since the amount of torque change is limited by the backlash vibration suppression torque command value change amount limiting control when the zero torque is passed, the gear backlash vibration can be reduced to a level that does not cause the driver to feel uncomfortable.
Further, when the motor torque is increased to a predetermined torque value, the friction brake torque is adjusted in accordance with the change of the motor torque so that the axle torque maintains a braking torque equivalent to the engine brake, that is, the axle torque does not fluctuate. Therefore, it is possible to reduce a sense of incongruity associated with fluctuations in vehicle deceleration.
Furthermore, in the first embodiment, when the accelerator operation is detected, the friction brake torque is set to zero, so that it is possible to suppress the deterioration of the acceleration performance of the vehicle due to the braking torque by the friction brake.

Next, the effect will be described.
The control device for an electric vehicle according to the first embodiment has the following effects.
(1) Friction brakes (braking control device 113, brake calipers 116a, 116b, 116c, 116d) that apply braking force to the wheels FL, FR, RL, RR, and a brake stroke sensor 111a that detects the driver's brake operation status The braking / driving torque is applied to the wheels FL, FR, RL, and RR connected via the accelerator stroke sensor 111b that detects the driver's accelerator operation state and the gear transmission mechanism (reduction gear 104, differential gear 105). And a vehicle controller 111 that calculates a motor torque command value for controlling and driving the motor 100 based on an accelerator operation amount detected by the accelerator stroke sensor 111b. The vehicle controller 111 includes a brake stroke sensor The accelerator stroke sensor 111b detects the accelerator operation after 111a detects that the brake operation state has changed from the operation state to the non-operation state. There until is detected with a coasting generator 111c that generates a coasting state by operating the friction brakes and the motor 100.
Therefore, acceleration performance according to the driver's acceleration request can be realized.
(2) The vehicle controller 111 controls the backlash vibration suppression torque that limits the increase amount per unit time of the torque of the motor 100 driven based on the motor torque command value when the torque of the motor 100 is switched from the braking torque to the driving torque. The coast running generation unit 111c includes a command value change amount limiting unit 207. generate.
Therefore, the gear backlash vibration can be reduced to a level that does not give the driver a sense of incongruity, and the sense of incongruity associated with fluctuations in the deceleration of the vehicle can be reduced.
(3) When the accelerator operation state is detected by the accelerator stroke sensor 111b, the coast running generator 111c sets the braking force by the friction brake to zero.
Therefore, it is possible to suppress the deterioration of the acceleration performance of the vehicle due to the braking torque by the friction brake at the start of the accelerator operation.

100 electric motor
104 Reducer (gear transmission mechanism)
105 Differential gear (gear transmission mechanism)
111 Vehicle controller (control unit)
111a Brake stroke sensor (brake operation state detector)
111b Accelerator stroke sensor (Accelerator operation state detector)
111c Coast running generator
113 Braking control device (braking force generator)
116a, 116b, 116c, 116d Brake calipers (braking force generator)
207 Backlash vibration suppression torque command value change amount limiting unit (Motor torque change amount limiting control unit)
FL, FR, RL, RR each wheel

Claims (3)

A braking force generator that applies braking force to the wheels;
A brake operation state detection unit for detecting the brake operation state of the driver;
An accelerator operation state detector for detecting the driver's accelerator operation state;
An electric motor for applying braking / driving torque to wheels connected via a gear transmission mechanism;
A control unit for calculating a motor torque command value for braking / driving the electric motor based on the accelerator operation amount detected by the accelerator operation amount detection unit;
With
The control unit includes a period from when the brake operation state detection unit detects that the brake operation state has changed from an operation state to a non-operation state until the accelerator operation state is detected by the accelerator operation state detection unit. A control apparatus for an electric vehicle, comprising: a coasting generation unit that operates a braking force generation unit and the electric motor to generate a coasting state. In the control apparatus of the electric vehicle according to claim 1,
The control unit is configured to limit a motor torque change amount that limits an increase amount per unit time of the torque of the electric motor driven based on the motor torque command value when the torque of the electric motor is switched from a braking torque to a driving torque. With a control unit,
The coast running generation unit generates a coast running state based on a driving torque by the electric motor and a braking torque by the braking force generation unit restricted by the motor torque change amount restriction control unit. Control device. In the control apparatus of the electric vehicle according to claim 1 or 2,
The coasting generator is configured to reduce the braking force generated by the braking force generator when the accelerator operation state is detected by the accelerator operation state detector.

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