JP2012114974A - Control apparatus for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive control apparatus for electric vehicle, capable of suppressing overcurrents and temperature rises of an inverter when an estimated rotor position is deviated from a true position.SOLUTION: The control apparatus for electric vehicle includes: a power converter 3 that converts a direct current into an alternating current with any frequency to drive a synchronous motor 4; a speed calculation section 67 that estimates a rotational speed of the synchronous motor 4 by calculation; control sections 61-64 which control an output voltage of the power converter 3 based on the rotational speed estimated by an input torque command and the speed calculation section 67; a failure determination section 73 that determines whether the rotational speed estimated by the speed calculation section 67 is an abnormal value and outputs a signal indicating that an abnormality has been detected in the control sections 61-64.

Description

  The present invention relates to an electric vehicle control device that controls an electric motor without using a speed sensor or a rotational position sensor.

  In an electric vehicle control device, an electric vehicle control device is known in which a magnetic pole position (rotor position) of the synchronous motor is detected by a detector in order to drive and control the synchronous motor. In such a conventional electric vehicle control device, a rotor position detection sensor for the synchronous motor and its wiring are required, and the electric vehicle becomes expensive. In addition, there is a problem that it is necessary to perform the maintenance and takes time. In order to avoid such a problem, various electric vehicle control devices that use the magnetic saliency of the permanent magnet rotor in the synchronous motor and control the synchronous motor without using the rotor position detection sensor have been proposed. Yes. In such a conventional example, among the plurality of fixed windings of a synchronous motor, there is one that observes a line voltage generated between two phases and estimates a rotational speed and a rotor position of the synchronous motor.

  In the above conventional example, accurate detection of the line voltage is required, and the line voltage is small in the region where the rotation speed is low. Therefore, the position estimation may fail due to a detection error, resulting in overcurrent and accompanying temperature increase. . When such a state is maintained, the rotor position may converge to a target position, but in that case, it is desirable as an electric vehicle control device, for example, a large torque fluctuation occurs transiently and riding comfort deteriorates. It is not a thing.

  The configuration of another conventional example is shown in FIG. In FIG. 8, 1 is a pantograph for receiving power from an overhead line as a voltage power source, 2 is a smoothing capacitor for smoothing DC voltage, 3 is an inverter for converting DC voltage into AC voltage of variable voltage variable frequency (VVVF), 4 A main motor 5 serving as a load device is a current detector that detects an inverter output current.

  Reference numeral 6 denotes a control circuit for the inverter 3. The control circuit includes a current command generation unit 61, a current control unit 62, a coordinate conversion unit 63, a PWM control unit 64, a coordinate conversion unit 65, an integrator 66, and a speed calculation unit 67. Composed.

  The current command creation unit 61 inputs a torque command from a mascot of the cab, and outputs a torque current command IqRef and a magnetic flux current command IdRef to the current control unit 62. The current control unit 62 generates a q-axis voltage VqPI and a d-axis voltage from the torque current Iq and magnetic flux current Id input from the coordinate conversion unit 65 and the current command IqRef and magnetic flux current command IdRef input from the current command creation unit 61. VdPI is calculated and output to the coordinate conversion unit 63. Here, since the q-axis voltage VqPI and the d-axis voltage VdPI are voltage values calculated based on the actually measured torque current Iq and magnetic flux current Id, they can be actually generated voltages.

  Based on the phase θ (estimated rotor position) output from the integrator 66, the coordinate conversion unit 63 generates a voltage command Vu, Vv, Vw from the q-axis voltage VqPI and the d-axis voltage VdPI input from the current control unit 62. Is output to the PWM control unit 64. The PWM control unit 64 generates a gate signal from the voltage commands Vu, Vv, and Vw input from the coordinate conversion unit 63 and outputs the gate signal to the gate of the inverter 3.

  The coordinate conversion unit 65 converts the current values Iu and Iw detected by the current detector 5 into a torque current Iq and a magnetic flux current Id based on the phase θ input from the integrator 66 and outputs the torque current Iq and the magnetic flux current Id to the speed calculation unit 67. To do. The speed calculation unit 67 calculates the estimated angular velocity ω1 of the electric motor 4 from the q-axis voltage VqPI and d-axis voltage VdPI input from the current control unit 62 and the torque current Iq and magnetic flux current Id input from the coordinate conversion unit 65. Output to the integrator 66. The integrator 66 integrates the angular velocity ω1 input from the velocity calculation unit 67 and outputs a phase θ. The phase θ has a large error in the initial stage of operation, but converges to a true value by performing speed estimation by the speed calculation unit 67 during operation.

JP 2006-217754 A

  In the electric vehicle control apparatus that controls the electric motor without using the rotor position sensor as described above, it is essential that the estimated (calculated) rotor position matches the true rotor position. When the estimated rotor position is different from the true rotor position, there arises a problem that the predetermined torque performance cannot be obtained. Further, although depending on the control method, there are cases where deterioration of ride comfort due to torque fluctuation, overcurrent, and accompanying temperature increase, and the like occur.

  In the electric vehicle control apparatus that controls the electric motor by the VVVF inverter without using the rotor position sensor, the present invention is designed to suppress overcurrent and temperature rise when the estimated rotor position is different from the true position. It is an object of the present invention to provide an electric vehicle drive control device capable of reducing a difference between a vehicle acceleration / deceleration and an actual acceleration / deceleration to suppress a decrease in vehicle thrust.

  An electric vehicle control device according to an embodiment of the present invention receives a power converter that converts a direct current into an alternating current of an arbitrary frequency and drives an electric motor, and a speed calculation means that estimates a rotational speed of the electric motor by calculation. Based on the torque command and the rotation speed estimated by the speed calculation means, the control means for controlling the output voltage of the power converter, and the rotation speed estimated by the speed calculation means is an abnormal value. And an abnormality determination means for outputting a signal indicating that an abnormality has been detected in the control means.

The block diagram which shows the structure of the electric vehicle control apparatus of 1st Embodiment. FIG. 6 is a vector diagram when the angular velocity ω1 calculated by the velocity calculation unit matches a true value. The block diagram which shows the structural example of the speed estimation part of FIG. The block diagram which shows the structure of the electric vehicle control apparatus of 2nd Embodiment. The block diagram which shows the structure of the electric vehicle control apparatus of 3rd Embodiment. The block diagram which shows the structure of the electric vehicle control apparatus of 4th Embodiment. The block diagram which shows the structure of the electric vehicle control apparatus of 5th Embodiment. The block diagram which shows the structure of a prior art example.

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

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of the electric vehicle control apparatus according to the first embodiment. The same components as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 1, 68 is a multiplier, 69a and 69b are adders, 70 is a subtractor, 71 is an absolute value calculator that calculates an absolute value, and 72 is a comparator that compares an input value with a predetermined value. The speed calculation unit 67 calculates the estimated angular velocity ω1 of the electric motor 4 based on the q-axis voltage VqPI and the d-axis voltage VdPI, the torque current Iq, and the magnetic flux current Id, and the q-axis voltage command VqCRef and the d-axis voltage command VdCRef. Is output. The current command generator 61, the current controller 62, the coordinate converter 63, the PWM controller 64, the coordinate converter 65, and the integrator 66 are rotations estimated by the torque command and speed calculator 67 input from the outside. It functions as a control means for controlling the power converter 3 based on information including the angular velocity.

  Hereinafter, the operation of the present embodiment will be described in detail. FIG. 2 is a vector diagram when the angular velocity ω <b> 1 calculated by the velocity calculation unit 67 matches the true value (actual value). At this time, the actual voltage vector V matches the voltage vector Vc indicated by the voltage command value. Accordingly, the d-axis voltage VdPI and the d-axis voltage command value VdRef are equal, and the q-axis voltage VqPI and the q-axis voltage command value VqRef are equal. In addition, the actual current vector I and the current vector Ic indicated by the current command match. Therefore, the magnetic flux current Id and the magnetic flux current command IdRef are equal, and the torque current Iq and the torque current command IqRef are equal.

  The actual motor output POWER is obtained by the following equation using the voltage-current equation.

POWER = VdPI × Id + Iq × VqPI (1)
On the other hand, the motor output to be controlled by the inverter control circuit 6, that is, the motor output command POWEREMF is obtained by the following equation.

VdCRef = R1 × IdRef−ω1 × Lq × IqRef (2)
VqCRef = R1 × IqRef−ω1 × Ld × IdRef + ω1 × Φ (3)
POWEREMF = VdCRef × IdRef
+ IqRef × VqCRef (4)
Here, R1: motor resistance value Ld: d-axis motor leakage inductance Lq: q-axis motor leakage inductance ω1: inverter frequency Φ: magnetic flux The speed calculation unit 67 calculates Expressions (2) and (3), and adds an adder 69a. Computes equation (4). When the estimated rotor position matches the true value, POWER in Equation (1) and POWEREMF in Equation (4) match, and the following relationship is obtained.

VdPI × Id + Iq × VqPI = VdCRef × IdRef
+ IqRef × VqCRef (5)
Therefore, the difference between both sides becomes zero as follows.

VdPI × Id + Iq × VqPI−VdCRef × IdRef
−IqRef × VqCRef = 0 (6)
The subtractor 70 calculates the above equation (6). On the other hand, when the estimated rotor position does not match the true value, the above equation (5) becomes the following equation (7), and the above equation (6) becomes a non-zero value. This value is set to POWER_D1.

VdPI × Id + Iq × VqPI ≠ VdCRef × IdRef
+ IqRef × VqCRef (7)
The ABS 71 generates an absolute value POWER_D2 of POWER_D1. When this POWER_D2 exceeds the predetermined set value POWER_D_SET, the comparison unit 72 determines that the estimated rotor position is different from the true value, and outputs “H” as the abnormality flag POWER_D. The multiplier 68, the adders 69a and 69b, the subtractor 70, the ABS 71, and the comparison unit 72 function as an abnormality determination unit that determines that the angular velocity ω1 estimated by the speed calculation unit 67 is an abnormal value. .

  As described above, it is possible to easily determine whether the estimated rotor position is different from the true value by comparing the actual motor output value with the motor output command.

(Second Embodiment)
FIG. 3 is a block diagram showing a schematic configuration of the second embodiment.

  This embodiment is different from the first embodiment of FIG. 1 in the method for determining abnormality of the rotor position. Japanese Patent No. 3719910 discloses one method for estimating the rotor position of an electric motor having electrical saliency such as a synchronous motor. In this document, a voltage or current having a frequency higher than the frequency of the AC is superimposed on the AC power supplied to generate torque in the motor, and the current or voltage obtained as a result has the same frequency as the applied high frequency. Extract and analyze the component waveforms to estimate the rotor position.

  FIG. 4 is a block diagram showing the configuration of the speed calculation unit 67 corresponding to the rotor position estimation means disclosed in the above-mentioned Japanese Patent No. 3719910. In FIG. 4, proportional integral (PI) control is performed so that the evaluation index Hdc becomes zero, and an estimated angular velocity ω1 is generated. When the evaluation index Hdc does not become zero, ω1 is different from the true value.

  In FIG. 3, the ABS 71 generates an absolute value Hdc1 of the evaluation index Hdc. When the absolute value Hdc1 exceeds the predetermined value HYOd_D_SET, the comparison unit 72 determines that the estimated speed is abnormal and outputs “H” as the abnormality flag HY0Cd_D. The ABS 71 and the comparison unit 72 function as an abnormality determination unit that determines that the angular velocity ω1 estimated by the velocity calculation unit 67 is an abnormal value.

  Also in this embodiment, it is possible to easily determine whether the estimated rotor position is different from the true value as in the first embodiment.

(Third embodiment)
FIG. 5 is a block diagram showing a schematic configuration of the third embodiment of the present invention.

  The rotor position abnormality determination method is different from the first embodiment of FIG. The operation of this embodiment will be described with reference to FIG. The q-axis induced voltage Eq induced in the motor is obtained by the following equation based on the voltage-current equation.

Eq = VqPI−R × Iq−ω × Ld × Id (8)
On the other hand, the q-axis induced voltage command EqRef to be controlled by the inverter control circuit 6 is obtained by the following equation.

EqRef = VqCRef
−R × IqRef−ω1 × Ld × IdRef (9)
here,
Eq: q-axis induced voltage EqRef: q-axis induced voltage command VqPI: q-axis voltage VqCRef: q-axis voltage command R: motor resistance value Iq: torque current IqRef: torque current command Id: magnetic flux current Id: magnetic flux current command Ld: d Shaft motor leakage inductance ω1: Estimated angular velocity The subtractor 70 outputs the q-axis induced voltage Eq, and the subtractor 80 outputs the q-axis induced voltage command EqRef.

  When the estimated rotor position θ matches the true value, the equations (8) and (9) match, and the relationship shown in the following equation is obtained.

VqPI-R × Iq + ω × Ld × Id =
VqCRef−R × IqRef + ω1 × Ld × IdRef (10)
Therefore, the difference between both sides is zero.

VqPI-R × Iq + ω × Ld × Id
−VqCRef + R × IqRef−ω1 × Ld × IdRef = 0 (11)
On the other hand, when the estimated rotor position θ does not coincide with the true value, both sides of the equation (10) do not coincide as in the following equation, and the equation (11) is a non-zero value. This value is defined as Eq1.

VqPI−R × Iq + ω × Ld × Id ≠ VqCRef−R × IqRef + ω1 × Ld × IdRef (12)
The subtractor 81 calculates “Eq−EqRef” and outputs Eq1. The ABS 71 generates an absolute value Eq2 of Eq1. When this Eq2 exceeds the predetermined set value Eq_D_SET, the comparison unit 72 determines that the estimated rotor position is different from the true value, and outputs “H” as the abnormality flag Eq_D. The multiplier 68, the adder 69, the subtracters 70, 80, 81, the ABS 71, and the comparison unit 72 serve as abnormality determination means for determining that the angular velocity ω1 estimated by the velocity calculation unit 67 has become an abnormal value. Function.

  As described above, it is possible to easily determine whether or not the estimated rotor position θ is different from the true value by comparing the induced voltage induced in the motor with the induced voltage command.

(Fourth embodiment)
FIG. 6 is a block diagram showing a schematic configuration of the fourth embodiment.

This embodiment differs from the first embodiment shown in FIG. 1 in that one electric vehicle control device includes a plurality of inverter devices. FIG. 6 shows an example in which two inverter control circuits of a first inverter control circuit 6a and a second inverter control circuit 6b are provided in one electric vehicle control device. Here, the rotational speeds of the wheels driven by the motors are the same.

  The subtractor 70 calculates the difference between ω1_1 calculated by the speed calculation unit of the first inverter control circuit 6a and ω1_2 calculated by the speed calculation unit of the second inverter control circuit 6b, and outputs it as FR_D1. The ABS 71 generates an absolute value FR_D2 of FR_D1. When this FR_D2 exceeds the predetermined set value FR_D_SET, the comparison unit 72 determines that the estimated rotor position is different from the true value, and outputs “H” as the abnormality flag FR_D. The subtractor 70, the ABS 71, and the comparison unit 72 function as an abnormality determination unit that determines that the angular velocity ω1 estimated by the speed calculation unit is an abnormal value.

  As described above, by comparing the motor rotation speed between the first inverter control circuit and the second inverter control circuit, it can be easily determined whether the estimated rotor position is different from the true value.

  The same applies to the case where three or more inverter control circuits are provided, and it is possible to determine whether or not there is an abnormality by comparing the motor rotation speeds.

(Fifth embodiment)
FIG. 7 is a block diagram showing a schematic configuration of the fifth embodiment.

  The OR flag 73 is used to calculate the logical sum FED_D of the abnormality flag calculated by the rotor position abnormality detection method described in the first to fourth embodiments in FIG. The inversion circuit 74 inverts FED_D to / FED_D, and outputs it to the AND circuit 75. The AND circuit 75 calculates the logical product of the gate signal output from the PWM control unit and the / FED_D signal to obtain a final gate signal. When an abnormality in the estimated rotor position θ is detected, all the output gate signals of the AND circuit 75 are “L”, and the vehicle travels inertially. Thereafter, the inverter 3 is restarted, and a normal rotor position is obtained.

  When the rotation of the motor 4 is started, an error in the estimated rotor position θ is large and an abnormality may be detected. In such a case, the approximate rotational speed value is obtained from the output waveform of the interphase voltage sensor provided between the motor 4 and the inverter 3. By applying this approximate rotational speed value to the control at the start of rotation of the motor 4, detection of an abnormality in the rotor position θ can be avoided.

  As described above, according to at least one embodiment, by detecting the abnormality of the rotor position, the gate signal is turned off to suppress overcurrent and temperature rise, and the planned vehicle acceleration / deceleration and the actual acceleration / deceleration An electric vehicle drive control apparatus and method capable of reducing the difference from the above and suppressing a decrease in vehicle thrust are provided.

  The above description is an embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. For example, various inventions can be configured by appropriately combining a plurality of constituent elements disclosed in the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Pantograph, 2 ... Smoothing capacitor, 3 ... Inverter, 4 ... Electric motor, 6 ... Inverter control circuit, 61 ... Current command preparation part, 62 ... Current control part, 63, 65 ... Coordinate control part, 64 ... PWM control part, 66 ... Integral unit, 67 ... Speed calculating unit, 68 ... Multiplier, 69 ... Adder, 70 ... Subtractor, 71 ... Absolute value calculating unit, 72 ... Comparator, 73 ... OR circuit, 74 ... Inverting circuit, 75 ... AND circuit.

Claims (6)

A power converter that converts direct current into alternating current at an arbitrary frequency and drives an electric motor;
A speed calculation means for estimating a rotation speed of an electric motor driven by alternating current converted by the power converter;
Control means for controlling the power converter based on information including a torque command input from the outside and information including the rotational speed estimated by the speed calculation means;
An abnormality determining means for determining that the rotational speed estimated by the speed calculating means is an abnormal value, and outputting a signal indicating that an abnormality is detected in the control means;
An electric vehicle control device comprising:   The electric vehicle control device according to claim 1, wherein the abnormality determination unit determines that the estimated rotation speed is an abnormal value based on a difference between an electric motor output and a control motor output command.   The electric vehicle control device according to claim 1, wherein the abnormality determination unit determines that the estimated rotation speed is an abnormal value based on the estimated evaluation index of the rotation speed.   The said abnormality determination means determines whether the said estimated rotational speed became an abnormal value based on the difference of the induced voltage which generate | occur | produces in the said electric motor, and the induced voltage command on control. Electric vehicle control device. Controlling the second electric motor, second speed calculating means for estimating the rotational speed of the second electric motor, a second power converter for driving the second motor, and the second power converter A second control unit,
The abnormality determining unit is configured to calculate the first and second speeds based on a difference speed between the rotation speed estimated by the first speed calculation unit and the rotation speed estimated by the second speed calculation unit. 2. The electric vehicle control device according to claim 1, wherein it is determined that the rotational speed estimated by one of the means is an abnormal value.   The control means stops the power converter and restarts the power converter when it is determined by the determination means that the estimated rotation speed has become an abnormal value. The electric vehicle control device according to claim 1.

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