JP2006197658A - Electric vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric vehicle controller in which reverse rotation of a motor can be prevented just before stopping the electric vehicle even when the motor is driven under speed sensorless vector control and thereby riding comfort can be enhanced. <P>SOLUTION: When a motor is controlled by speed sensorless vector control not using a speed sensor for detecting the motor speed, a brake time inverter frequency limit section 16 limits the inverter frequency fi from a speed sensorless vector control operating section 13 such that an inverter frequency fi' to a PWM gate operating section 14 outputting a gate signal to a VVVF inverter 15 does not have a negative value at the time of braking the motor. Comfortableness is enhanced by preventing the phase sequence of inverter output voltage from being changed just before stopping the motor thereby preventing the reverse rotation of the motor 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric vehicle control device that performs vector control without a speed sensor for detecting the speed of an electric motor for driving an electric vehicle.

  In the case of an electric vehicle control apparatus that performs vector control without having a speed sensor for detecting the speed of the electric motor for driving the electric car, the frequency of the VVVF inverter (variable voltage variable frequency inverter) for driving the electric motor is It is determined from the slip frequency command value, motor voltage command value, and motor current value. The speed of the electric motor is calculated as a value obtained by subtracting the command value of the slip frequency from the VVVF inverter frequency.

  On the other hand, the brake torque of the electric motor is different from the braking force of the mechanical brake, and the torque is output in the direction in which the electric motor rotates in the reverse direction. Therefore, if the motor continues to generate brake torque even if the motor stops, the motor reverses. Therefore, it is necessary to accurately detect that the motor has stopped and to reduce the brake torque of the motor to zero.

There is one that detects the actual speed of the motor, narrows down the torque current pattern according to the actual speed of the motor, and controls the torque current to be zero when the actual speed of the motor is zero (for example, patents) Reference 1).
JP 2001-251701 A

  However, since the thing of patent document 1 has a speed sensor, although the actual speed of an electric motor can be detected, in speed sensorless vector control which does not have a speed sensor, an electric motor speed cannot be read. When vector control without an electric motor speed sensor is performed, the electric motor speed is a so-called estimated value calculated as a value obtained by subtracting the command value of the slip frequency from the frequency of the VVVF inverter. This estimated value may deviate from the actual speed due to an error in the inverter output current sensor or DC voltage sensor.Especially, when the speed is low, such as just before the motor stops, the inverter output voltage is small, so the error in the estimated speed value may also be There are characteristics that are easy to come out.

  Since the motor stoppage is detected based on the estimated speed of the motor, if the estimated motor speed value is exactly the same as the actual speed just before the motor stops, the motor will reverse. However, if the actual motor speed is zero and the estimated motor speed is not zero, the brake torque, that is, the torque will continue to be output in the reverse direction until the estimated motor speed reaches zero. Will be reversed.

  Since the error between the estimated motor speed and the actual motor speed is suppressed to approximately 1 Hz or less, when the estimated motor speed becomes zero, the reverse torque of the motor is controlled to zero. For this reason, the reverse rotation of the electric motor is only required temporarily, but when such a phenomenon occurs, the ride comfort immediately before the stop is greatly deteriorated.

  FIG. 4 is a block diagram of a conventional electric vehicle control device. The torque pattern of the electric motor 12 from the torque pattern calculation unit 11 is input to the speed sensorless vector control calculation unit 13 as an electric motor torque command. The speed sensorless vector control calculation unit 13 calculates the inverter frequency fi based on the torque pattern, and outputs it to the VVVF inverter 15 via the PWM gate calculation unit 14. Thereby, the VVVF inverter 15 drives the electric motor 12.

  FIG. 5 is an explanatory diagram of the operation of the conventional electric vehicle control device during braking. Since the slip frequency fs of the motor 12 is negative during braking, the inverter frequency fi is smaller than the motor speed v. When the motor speed v decreases, the inverter frequency fi approaches zero, and at the time t1 when the motor speed v decreases to the same value as the slip frequency fs, the inverter frequency fi becomes zero. If the state is continued as it is, the inverter frequency fi turns negative, the phase order of the inverter output voltage is switched, and the motor speed becomes zero at time t2.

  FIG. 6 is an explanatory diagram of the operation of the conventional electric vehicle control device during braking when the actual motor speed v is deviated from the estimated motor speed v0. When the actual motor speed v is deviated from the estimated motor speed v0, the slip frequency command value is continuously output if the estimated speed v0 is a positive value even if the actual motor speed v is zero at time t2. Accordingly, the actual slip frequency fs of the electric motor 12 is continuously output, and torque is continuously output in the direction in which the electric motor 12 is reversed. As a result, the motor 12 starts to reverse at time t3, and finally at time t4 when the estimated motor speed value v0 becomes zero, the slip frequency command value is set to zero, and the torque for reversing the motor 12 is reduced. Stop. When the actual motor speed v deviates from the estimated motor speed v0, the motor reverses, so that the riding comfort immediately before the electric vehicle stops is deteriorated.

  An object of the present invention is to provide an electric vehicle control device that can prevent reverse rotation of the electric motor just before stopping the electric vehicle even when the electric motor is driven by speed sensorless vector control, and can improve riding comfort.

  The electric vehicle control device of the present invention is an electric vehicle control device that performs vector control of the electric motor by a VVVF inverter without a speed sensor for detecting the speed of the electric motor for driving the electric vehicle. A torque pattern calculation unit that calculates, a speed sensorless vector control calculation unit that outputs an inverter frequency based on a brake torque pattern calculated by the torque pattern calculation unit during braking of the electric vehicle, and a speed sensorless vector control calculation unit A brake inverter frequency limiter that limits the inverter frequency of the inverter so as not to output a negative inverter frequency, and a PWM gate that outputs a gate signal to the VVVF inverter based on the inverter frequency passed through the inverter frequency limiter With a computing unit And butterflies.

  ADVANTAGE OF THE INVENTION According to this invention, even when driving an electric motor by speed sensorless vector control, reverse rotation of an electric motor can be prevented just before the electric vehicle stops, and riding comfort can be improved.

  Embodiments of the present invention will be described below. FIG. 1 is a block diagram of an electric vehicle control apparatus according to the first embodiment of the present invention. In the first embodiment, a brake-time inverter frequency limiting unit 16 that limits the inverter frequency fi from the speed sensorless vector control calculation unit 13 is added to the conventional example shown in FIG. is there. The same elements as those in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  The brake torque pattern calculated by the torque pattern calculation unit 11 is input to the speed sensorless vector control calculation unit 13 as a motor torque command value. The speed sensorless vector control calculation unit 13 calculates the inverter frequency fi based on the torque pattern and outputs the inverter frequency fi to the brake inverter frequency limiting unit 16. The brake inverter frequency limiting unit 16 limits the inverter frequency fi so as not to be equal to or less than zero during braking of the electric vehicle, and outputs the inverter frequency fi ′ to which the limitation is applied to the PWM gate calculation unit 14. The PWM gate calculation unit 14 creates a PWM gate signal based on the inverter frequency fi ′ and drives the VVVF inverter 15. Thereby, the electric motor 12 does not reverse.

  FIG. 2 is an explanatory diagram of an operation during braking of the electric vehicle control device according to the second embodiment of the present invention. Since the slip frequency fs of the motor 12 is negative during braking, the inverter frequency fi is smaller than the motor speed v. When the motor speed v decreases, the inverter frequency fi approaches zero, and the inverter frequency fi becomes zero at time t1 when the motor speed v decreases to the same value as the slip frequency fs.

  At the time t1 when the inverter frequency fi becomes zero, the brake inverter frequency limiting unit 16 limits the inverter frequency fi ′ output to the PWM gate calculation unit 14 with a positive value so as not to be negative. It is possible to prevent the phase order from being changed. If the phase sequence of the inverter output voltage does not change, the motor 12 will not reverse even if the estimated motor speed value v0 deviates from the actual speed.

  According to the first embodiment, since the inverter frequency fi 'output to the PWM gate calculation unit 14 does not become negative just before stopping during braking, the phase sequence of the inverter output voltage does not change. Therefore, the reverse rotation of the electric motor 1 can be prevented, and the riding comfort immediately before stopping the electric vehicle can be improved.

  Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram of an electric vehicle control apparatus according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that the inverter frequency fi from the speed sensorless vector control calculation unit 13 is zero instead of the brake inverter frequency limiting unit 16. The inverter gate-off command output unit 17 that outputs the gate-off command s0 to the PWM gate calculation unit 14 is provided. The same elements as those in FIG.

  The inverter gate-off command output unit 17 detects that the inverter frequency fi from the speed sensorless vector control calculation unit 13 has become zero, and outputs a gate-off command s0 to the PWM gate calculation unit 14. As a result, the PWM gate calculation unit 14 turns off the gate signal to the VVVF inverter 15, so that the motor 12 does not reverse.

  That is, since the gate signal of the VVVF inverter 15 is turned off when the inverter frequency fi becomes zero, the inverter frequency fi is negative and the phase sequence of the inverter output voltage is not reversed, and the motor 12 is not reversed. Can be controlled.

  According to the second embodiment, since the inverter frequency fi is not negative just before stopping during braking, the phase sequence of the inverter output voltage does not change. Therefore, the reverse rotation of the electric motor 12 can be prevented, and the riding comfort can be improved just before the electric vehicle is stopped.

The block block diagram of the electric vehicle control apparatus concerning the 1st Embodiment of this invention. Operation | movement explanatory drawing at the time of the brakes of the electric vehicle control apparatus concerning the 2nd Embodiment of this invention. The block block diagram of the electric vehicle control apparatus concerning the 2nd Embodiment of this invention. The block block diagram of the conventional electric vehicle control apparatus. Operation | movement explanatory drawing at the time of the brake of the conventional electric vehicle control apparatus. Operation | movement explanatory drawing at the time of the brake of the conventional electric vehicle control apparatus when the motor actual speed v and the motor estimated speed v0 have shifted | deviated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Torque pattern calculating part, 12 ... Electric motor, 13 ... Speed sensorless vector control calculating part, 14 ... PWM gate calculating part, 15 ... VVVF inverter, 16 ... Inverter frequency limiting part at the time of a brake, 17 ... Inverter gate off command output part

Claims (2)

  In an electric vehicle control apparatus that performs vector control of the electric motor by a VVVF inverter without having a speed sensor for detecting the speed of the electric vehicle driving electric motor, a torque pattern calculating unit that calculates a torque pattern of the electric motor, A speed sensorless vector control calculation unit that outputs an inverter frequency based on the torque pattern calculated by the torque pattern calculation unit, and limits the inverter frequency from the speed sensorless vector control calculation unit and does not output a negative inverter frequency. An electric vehicle control device comprising: an inverter frequency limiting unit for braking, and a PWM gate arithmetic unit for outputting a gate signal to a VVVF inverter based on an inverter frequency passed through the inverter frequency limiting unit. In an electric vehicle control device that performs vector control of the electric motor by a VVVF inverter without having a speed sensor for detecting the speed of the electric vehicle driving electric motor, a torque pattern calculating unit that calculates a torque pattern of the electric motor, A speed sensorless vector control calculation unit that outputs an inverter frequency based on the torque pattern calculated by the torque pattern calculation unit, and a PWM gate that outputs a gate signal to the VVVF inverter based on the inverter frequency from the speed sensorless vector control calculation unit An electric vehicle control comprising: a calculation unit; and an inverter gate off command output unit that outputs a gate off command to the PWM gate calculation unit when the inverter frequency from the speed sensorless vector control calculation unit becomes zero apparatus.

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