JP2002058106A - Regenerative energy controller in electric motor car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent operating state of a brake from changing suddenly, and to prevent charging of a battery from becoming insufficient in an electric motor car which uses regenerative brake. SOLUTION: A torque computing means 11 computes a torque command for regenerating energy from a motor 35 to a motor-drive battery 31, on the basis of each operating state of the electric motor car and the characteristics of torque command stored in a torque map 12. A torque command suppressing means 13 conducts correcting, so as to reduce the torque command computed by the torque computing means, as the voltage of the motor-drive battery detected by a voltage sensor 21 becomes higher, and makes the command approach zero, when the detected voltage of the motor drive battery is not lower than a prescribed low voltage. A motor controller 20 regenerates energy from the motor to the motor-drive battery, on the basis of this corrected torque command, controls the output torque of the motor and drives the wheels, on the basis of a torque command computed separately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling regenerative energy recovered from a motor to a battery in an electric vehicle using a motor powered by a battery and driving wheels.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the overall configuration of an electric vehicle to which a regenerative energy control device for an electric vehicle according to the present invention is applied. 13 is the same as the above except that the device is not provided, and the conventional technology will be described with reference to FIG. In a conventional electric vehicle of this type, if an accelerator operation is performed by a manual accelerator lever or the like, the vehicle ECU (vehicle control device) 10 controls the motors 35a and 35b connected to the left and right wheels by a motor ECU (motor control device). The electric vehicle is driven by operating through the motor 20 and is stopped by operating the brake.
If a regenerative brake is provided in addition to the mechanical brake as the brake, a part of the kinetic energy of the electric vehicle is recovered as electric power by the motor drive battery (high-voltage battery) 31 at the time of the stop. Such a regenerative brake is also operated even when the accelerator operation amount is returned to 0 without operating the brake.

Next, the prior art electric vehicle will be described in more detail. The electric vehicle includes a vehicle ECU 10 that controls the operation of the entire electric vehicle, and a motor 35a that drives left and right wheels based on a command from the vehicle ECU 10.
The motor ECU 20 controls the operation of the motor ECU 35b. The two ECUs 10 and 20 are powered by a low-voltage battery 32, and each motor 35a and 35b is connected to a relay 3
Power is supplied from the motor driving battery 31 through the inverter 3 and the inverter 34.

The vehicle ECU 10 includes a main switch 15 of the electric vehicle and a brake sensor (brake switch) 16 which is closed when a brake operated by the user is operated.
And an accelerator sensor 17 for detecting an operation amount (opening degree) of an accelerator member such as an accelerator lever or an accelerator pedal operated by a user, and a shift position sensor 18 for detecting each of forward, reverse and neutral shift positions. Have been. Further, the vehicle ECU 10 controls the characteristics of the torque command value used when the wheels are driven by the motors 35a and 35b (see Ad and Ar in FIG. 3) in accordance with the respective operating states of the electric vehicle, and the motor drive from the motors 35a and 35b. Map 12 that stores the characteristics of torque command values (see Bd, Br, Cd, and Cr in FIG. 3) used to regenerate energy to the battery 31 for use in the electric vehicle detected by the sensors 16-18. Operating state and torque map 12
To regenerate energy from the motors 35a, 35b to the motor driving battery 31 based on the torque command value for driving the wheels by the motors 35a, 35b (hereinafter, simply referred to as the torque command value for driving the wheels). (Hereinafter simply referred to as a torque command value for regenerating energy). The relay 33 in the power supply circuit to the motors 35a and 35b is controlled by the vehicle ECU 10.

[0005] The motor ECU 20 includes a torque calculating means 11
Based on the torque command value calculated by
5a and 35b generate the torque according to the torque command value to drive each wheel.
The inverter 34 is controlled so as to regenerate energy from the battery b to the motor driving battery 31. The left and right wheels are always driven at rotational speeds corresponding to the left and right motors 35a and 35b, and the rotational speeds of the motors 35a and 35b are detected by respective rotational speed sensors 36a and 36b and transmitted to the vehicle ECU 10 via the motor ECU 20. Is done. The voltage of the motor driving battery 31 is detected by a voltage sensor 21 provided in the
Is transmitted to The voltage sensor 21 has a detection resolution of 0.5
It outputs a detection voltage in 0.5 volt increments. Both batteries 31 and 32 are charged by charger 30 connected to a 100 volt AC power supply when the electric vehicle is not used. Alternatively, a generator driven by an internal combustion engine may be mounted, and the batteries 31 and 32 may be charged by the generator during use of the electric vehicle.

[0006] As shown in FIG.
It stores the characteristics of the torque command value with respect to the rotation speed of each of the motors 35a, 35b, and includes six characteristics Ad, Ar, B
d, Br, Cd, and Cr. The characteristic Ad and the characteristic Ar are characteristics of a torque command value that maximizes an output possible range when the vehicle is driven by driving the wheels by the motors 35a and 35b.
The characteristic in the case of (forward) and the characteristic Ar are the characteristics in the case where the shift position is R (reverse). Characteristic Bd
And the characteristic Br are characteristics of a torque command value for regenerating energy when the brake is operated,
The characteristic Bd is the characteristic when the vehicle is moving forward, the characteristic Br
Is a characteristic when the vehicle is moving backward. The characteristic Cd and the characteristic Cr are characteristics of a torque command value for regenerating energy when the accelerator operation amount is set to 0, the characteristic Cd is a characteristic when the shift position is D, and the characteristic Cr is a characteristic when the shift position is R. It is a characteristic in the case. These characteristics in each operating state of the electric vehicle only correspond to the rotation speed of the motors 35a and 35b.

When the electric vehicle is in a normal running state, that is, when the brake sensor 16 has not detected the operation of the brake and the operation amount detected by the accelerator sensor 17 is not zero, the torque calculating means 11 determines the characteristics Ad and Characteristic A
r and a torque command value that maximizes the output possible range when the vehicle travels, based on the rotation speeds of the motors 35a and 35b detected by the rotation speed sensors 36a and 36b,
That is, a torque command value when the accelerator operation amount is the maximum is calculated, and a torque for driving wheels according to the accelerator operation amount at that time is calculated based on the torque command value and the operation amount detected by the accelerator sensor 17. Calculate the command value. The vehicle ECU 10 outputs the torque command value thus calculated to the motor ECU 20, and the motor ECU 20
As described above, based on this torque command value, each motor 35
a and 35b control the inverter 34 so as to drive each wheel. Thereby, the electric vehicle moves forward or backward according to the shift position with an output corresponding to the accelerator operation amount at that time.

If the driver applies a brake while the electric vehicle is traveling, the brake sensor 16 detects the operation of the brake. In this state, regardless of the accelerator operation amount, the torque calculating means 11 regenerates energy based on the characteristics Bd and Br and the rotational speeds of the motors 35a and 35b detected by the rotational speed sensors 36a and 36b. For the vehicle EC
U10 outputs this torque command value to the motor ECU 20, and the motor ECU 20 regenerates the energy from each of the motors 35a and 35b to the motor driving battery 31 based on the torque command value as described above.
4 is controlled. If the accelerator is closed without operating the brake while the electric vehicle is running, the brake sensor 1
6 is for detecting the operation of the brake and for detecting the accelerator sensor 17
Is zero. In this state, the torque calculator 11 calculates a torque command value for regenerating energy based on the characteristics Cd and Cr and the rotational speed of each of the motors 35a and 35b.
0 outputs this torque command value to the motor ECU 20, and the motor ECU 20 regenerates energy from each of the motors 35a and 35b to the motor driving battery 31 based on the torque command value, similarly to the case of operating the brake. The inverter 34 is controlled, but the degree of energy regeneration is smaller than when the brake is operated.

The regeneration of the energy is performed by each motor 35a,
35b for driving the motor by the current generated at 35b.
The charging is performed by charging the battery 1. When the charging current exceeds a certain allowable amount, the temperature of the motor driving battery 31 increases and the voltage increases, and the motor driving battery 31 deteriorates. Therefore, in the related art, for example, the voltage of the motor drive battery 31 is detected, and when the value becomes equal to or higher than a predetermined limit voltage, the charging current is cut off to stop the energy regeneration.

[0010]

In the above prior art in which energy is regenerated by using a regenerative brake in addition to a mechanical brake, the voltage of the battery for driving the motor is detected as described above, and the value of the voltage is detected. When the voltage exceeds the predetermined limit voltage, the charging current is cut off to stop the regeneration of energy, so that the voltage of the motor driving battery rises while the brake is operated and exceeds the predetermined limit voltage. When this happens, the regenerative brake will not operate, and the operating state of the brake will change, giving the driver an uncomfortable feeling. This manifests itself as a phenomenon of reduced brake operation on long downhills, but without any danger, mechanical brakes alone have sufficient braking capacity. Also, when the accelerator is closed without operating the brake during running, the somewhat weak regenerative brake due to the characteristic Cd and the characteristic Cr operates, but also in this case, the voltage of the motor driving battery rises and the predetermined voltage increases. Since the regenerative brake may not operate beyond the limit, the driver may feel uncomfortable.

The charging current allowed for the battery is as follows:
When the battery voltage is low, the battery voltage becomes large and the battery voltage becomes high, and becomes small.If a large charging current is given while the battery voltage is high, the battery voltage reaches a predetermined limit voltage before the battery is charged to the rated capacity. There is a problem that charging must be stopped and the battery cannot be completely charged. An object of the present invention is to solve each of these problems.

[0012]

A regenerative energy control device for an electric vehicle according to the present invention is provided with a motor driven by a motor driving battery and driven by a motor control device to drive wheels, and a brake sensor for detecting operation of a brake. An accelerator sensor for detecting an accelerator operation amount, and a torque for driving wheels by a motor used in an operation state in which the brake sensor does not detect the operation of the brake and the operation amount detected by the accelerator sensor is not zero. Characteristics of the command value and a torque command value for regenerating energy from the motor used in the operating state where the brake sensor detects the operation of the brake or the operation amount detected by the accelerator sensor is 0 to the motor driving battery. And a torque map that stores the characteristics of Torque calculating means for calculating a torque command value for driving wheels by a motor or a torque command value for regenerating energy in accordance with each operating state of the electric vehicle and each characteristic of the torque map based on each characteristic of the torque map. The motor control device controls the output torque of the motor based on the torque command value calculated by the torque calculation means, drives the wheels, or regenerates energy from the motor to the motor driving battery. In the regenerative energy control device for an electric vehicle, when the voltage of the motor driving battery detected by the voltage sensor is equal to or higher than a predetermined low voltage, the energy calculated by the torque calculating means is regenerated as the detected voltage increases. Command value to reduce the value of the torque command value to make it closer to 0 Comprising a control means, the motor control device is characterized in that it has to be regenerated energy from the motor to the motor drive battery based on the corrected torque command value.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A regenerative energy control device for an electric vehicle according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing a configuration of a regenerative energy control device in an electric vehicle according to the present invention, and FIG. 2 is a block diagram showing an entire configuration of one embodiment of an electric vehicle to which the regenerative energy control device in the electric vehicle according to the present invention is applied. It is. This embodiment is the same as the above-described prior art except that a torque command value suppressing unit 13 is provided and a part of the control content of the vehicle ECU 10 is different.

In a normal running state of the electric vehicle, the torque calculating means 11 operates as shown in FIG.
d, a characteristic Ar, a torque command value for driving the wheels based on the rotation speed of each of the motors 35a and 35b detected by the rotation speed sensors 36a and 36b, and the operation amount detected by the accelerator sensor 17, Vehicle E
The CU 10 outputs the calculated torque command value to the motor ECU 20, and the motor ECU 20 controls the inverter 34 based on the torque command value so that the motors 35a and 35b drive the wheels. As a result, the electric vehicle moves forward or backward with an output corresponding to the accelerator operation amount.

If the driver applies a brake while the electric vehicle is running, the brake sensor 16 detects the operation of the brake. In this state, irrespective of the accelerator operation amount, first, the torque calculating means 11 operates the motor 35a detected by the characteristic Bd and the characteristic Br and the rotation speed sensors 36a and 36b in the same manner as in the above-described prior art. , 35b are calculated based on the rotational speeds of the torques.

The torque command value for regenerating this energy is unchanged if the voltage of the motor driving battery 31 detected by the voltage sensor 21 is lower than a predetermined low voltage (for example, 78.0 volts), or higher. In some cases, the correction is made by the torque command value suppression means 13 of the vehicle ECU 10 as described below, and is output to the motor ECU 20. The correction of the torque command value when the voltage of the motor driving battery 31 is equal to or higher than a predetermined low voltage, as described later, regenerates the energy calculated by the torque calculation means 11 as the detected voltage increases. The value of the torque command value is reduced to approach 0, and the detected voltage increases to a predetermined limit voltage (for example, 9
When the voltage exceeds 2.5 volts), the torque command value is corrected to be zero. And the motor ECU 20
Controls the inverter 34 to regenerate energy from each of the motors 35a and 35b to the motor driving battery 31 based on the corrected or uncorrected torque command value.

If the accelerator is closed during operation of the electric vehicle without operating the brake, the brake sensor 16
Does not detect the operation of the brake and the operation amount detected by the accelerator sensor 17 is zero. In this state, similarly to the case where the brake is applied, first, the torque calculating means 11 calculates a torque command value for regenerating energy based on the characteristics Cd and Cr and the rotation speed of each of the motors 35a and 35b. I do. The torque command value for regenerating this energy is, as described above,
If the voltage of the motor driving battery 31 detected in step 1 is lower than the predetermined low voltage (same as above), the voltage is corrected by the torque command value suppression means 13 of the vehicle ECU 10 if the voltage is higher than the predetermined voltage, and output to the motor ECU 20. Is done. Then, the motor ECU 20 controls the inverter 34 in the same manner as described above to regenerate energy from the motors 35a and 35b to the motor driving battery 31.

Next, the calculation of the torque command value for regenerating the energy by the vehicle ECU 10 and the torque calculating means 11 and the correction of the thus calculated torque command value by the torque command value suppressing means 13 are shown in FIG. This will be described with reference to the flowchart shown in FIG.

The vehicle ECU 10 starts executing the processing shown in the flowchart of FIG. 4 every time an interrupt signal is input at a predetermined time interval. The vehicle ECU 10 first recognizes whether the shift position is N (neutral), R (reverse), or D (forward) by the shift position sensor 18 (step 100), and recognizes the same recognition value three times in succession. If it is (steps 101 to 104), a torque command value for energy regeneration corresponding to the recognized shift position is calculated (steps 110 to 115). If the shift position is N, a torque command value for energy regeneration corresponding to the shift position N is calculated in step 111, and this torque command value is zero.

If the shift position is R, a torque command value for energy regeneration corresponding to the shift position R is calculated in step 113. This calculation is performed separately for a case where the brake is operated while the electric vehicle is running and a case where the accelerator is closed without operating the brake. When the brake is activated while the electric vehicle is moving backwards, the vehicle ECU is activated regardless of the accelerator operation amount.
The torque calculation means 11 includes the characteristics Br and Bd of the torque map 12 and the rotation speed sensors 36a and 36b shown in FIG.
A torque command value for regenerating energy is calculated based on the rotation speed of each of the motors 35a and 35b detected by the above. If the accelerator is closed without operating the brake, the characteristic Cr of the torque map 12 and the detection A torque command value for regenerating energy is calculated based on the rotation speeds of the respective motors 35a and 35b.

If the shift position is D, a torque command value for energy regeneration corresponding to the shift position D is calculated in step 115. This calculation is also performed when the brake is activated while the electric vehicle is running,
This is performed separately when the accelerator is closed without operating the brake. When the brake is operated while the electric vehicle is moving forward, regardless of the accelerator operation amount, the torque calculation means 11 of the vehicle ECU 10 determines the characteristics Bd and Br of the torque map 12 shown in FIG. 3
When a torque command value for regenerating energy is calculated based on the rotation speeds of the motors 5a and 35b, and the accelerator is closed without operating the brake, the torque map 12
A torque command value for regenerating energy is calculated on the basis of the characteristic Cd and the detected rotational speeds of the motors 35a and 35b.

After calculating any of the torque command values for regenerating these energies, the vehicle ECU 10 performs torque command value suppression control in step 116. The contents of the torque command value suppression control are shown in the flowchart of FIG. First, the vehicle ECU 10 detects the voltage of the motor driving battery 31 by the voltage sensor 21 (step 20).
0), if the brake sensor 16 detects the operation of the brake or if the accelerator operation amount detected by the accelerator sensor 17 is 0 (steps 201 and 202),
Steps 210 to 22 by the torque command value suppressing means 13
7, the torque command value suppression control is performed. If the voltage of the motor drive battery 31 detected in step 200 (hereinafter simply referred to as battery voltage) is less than 78.0 volts, the torque command value suppressing means 13 performs the energy regeneration calculated in step 113 or 115 in FIG. (Hereinafter simply referred to as the torque command value calculated in FIG. 5) is not performed. If the detected battery voltage is 78.0-7
In the case of 8.5 volts, a correction is performed to multiply the torque command value calculated in FIG. 5 by 7/8 (steps 210 and 211).
If the detected battery voltage is 79.0 to 79.5 volts, a correction is made to multiply the torque command value calculated in FIG. 5 by 6/8 (steps 212 and 213). Similarly, the torque command value suppressing means 13 gradually decreases the multiplication factor as the detected battery voltage increases,
The torque command value calculated in FIG. 5 is corrected so as to decrease to approach 0 (steps 214 to 225). Then, when the detected battery voltage becomes 92.5 volts or more, the torque command value suppressing means 13 performs correction so that the torque command value calculated in FIG. 5 becomes 0 (steps 226 and 227).

The motor ECU 20 sets the torque command value corrected in this way (when the detected battery voltage is 78.0 volts or more) or not corrected (when the detected battery voltage is less than 78.0 volts). On the basis of,
From each of the motors 35a and 35b, a motor driving battery 31 is provided.
The inverter 34 is controlled so as to regenerate energy. Accordingly, the charging current from the motors 35a and 35b to the motor driving battery 31 also decreases as the voltage of the motor driving battery 31 increases and approaches zero, so that the ratio of the regenerative energy in the braking force generated during braking is also reduced. It decreases as the voltage of the driving battery 31 increases. When the voltage of the motor driving battery 31 becomes higher than a predetermined limit voltage, the motor driving battery 31
The charging current from the motors 35a and 35b is set to 0 in order to prevent the deterioration of the braking force. At this point, the ratio of the regenerative energy in the braking force is sufficiently reduced. The change in the operating state of the vehicle is zero or very slight, and the driver does not feel uncomfortable.

In general, the charging current allowed for a battery is large when the battery voltage is low, becomes small when the battery voltage is high, and when a large charging current is given while the battery voltage is high, the rated capacity of the battery is reduced. Before the battery is charged, the battery voltage must reach a predetermined limit voltage and the charging must be stopped. However, in this embodiment, since the charging current decreases as the voltage of the motor driving battery 31 increases, it is possible to reliably charge the motor driving battery 31 to the rated capacity without fear of deterioration.

[0025]

According to the present invention, when the voltage of the motor driving battery is equal to or higher than a predetermined low voltage, the torque command value for regenerating the energy decreases as the detected voltage increases and becomes zero. Is corrected so that it approaches
The charging current to the motor driving battery also decreases as the voltage of the motor driving battery increases and approaches zero, and the ratio of the regenerative energy in the braking force generated during braking also increases as the voltage of the motor driving battery increases. Decrease. When the voltage of the motor driving battery becomes equal to or higher than a predetermined limit voltage, the regenerative energy recovered from the motor to the motor driving battery also becomes 0, but at that time, the ratio of the regenerative energy in the braking force decreases sufficiently. Therefore, the change in the operation state of the brake is zero or very slight, and the driver does not feel uncomfortable.

Further, if a large charging current is applied in a state where the battery voltage is high, there is a problem that the battery voltage reaches a predetermined limit voltage and charging must be stopped before the battery is charged to the rated capacity. However, in the present invention, the charging current decreases as the voltage of the motor driving battery increases, so that the battery can be reliably charged to the rated capacity without fear of deteriorating the motor driving battery.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a regenerative energy control device in an electric vehicle according to the present invention.

FIG. 2 is a block diagram showing an overall configuration of an example of an electric vehicle to which a regenerative energy control device for an electric vehicle according to the present invention is applied.

FIG. 3 is a diagram illustrating an example of a characteristic of a torque command value used in the present invention.

FIG. 4 is a diagram showing an example of a flowchart for calculating a torque command value for regenerating energy in the present invention.

5 is a diagram showing an example of a flowchart for correcting the torque command value calculated in FIG.

[Explanation of symbols]

11: Torque calculation means, 12: Torque map, 13: Torque command value suppression means, 16: Brake sensor (brake switch), 17: Accelerator sensor, 20: Motor control device (motor ECU), 21: Voltage sensor, 31 ... Motor drive battery (high-voltage battery), 35 (35
a, 35b) ... motor.

Continued on front page F-term (reference) 3D046 BB03 HH00 HH02 HH05 HH51 JJ24 5H115 PA01 PA15 PG04 PI16 PI22 PI29 PO02 PO06 PO17 PU08 PU26 PV09 QE10 QE13 QH08 QI04 QI07 QN03 SE04 SE06 TI05 TO13 TO21 TO23 TO30

Claims (1)

[Claims] 1. A motor that is powered by a motor driving battery and drives wheels by being controlled by a motor control device, a brake sensor that detects an operation of a brake, an accelerator sensor that detects an accelerator operation amount, and the brake sensor Characteristics of a torque command value for driving the wheels by the motor used in an operation state in which the operation of the brake is not detected and the operation amount detected by the accelerator sensor is not 0, and the brake sensor operates the brake. And a torque map storing characteristics of a torque command value for regenerating energy from the motor to the motor driving battery used in an operation state in which the operation amount detected by the accelerator sensor is 0 or , Each operating state of the electric vehicle detected by each of the sensors and It is provided with torque calculating means for calculating a torque command value for driving the wheels by the motor or a torque command value for regenerating energy based on each characteristic of the torque map in accordance with each operation state, The motor control device drives the wheels by controlling the output torque of the motor based on the torque command value calculated by the torque calculation means, or regenerates energy from the motor to the motor driving battery. In the regenerative energy control device for an electric vehicle, when the voltage of the motor driving battery detected by a voltage sensor is equal to or higher than a predetermined low voltage, the torque is calculated by the torque calculating means as the detected voltage increases. Reduce the value of the torque command value for regenerating the energy Regenerative energy in the electric vehicle, wherein the motor control device regenerates energy from the motor to the motor driving battery based on the corrected torque command value. Control device.