JP2010246336A - Motor control device and motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high precision torque control by allowing a voltage to be outputted in accordance with a command value without reducing a control period during rectangular wave control. <P>SOLUTION: A motor control device is provided with: a voltage phase control part for calculating a voltage phase angle command value; a counter for counting in a fixed period; an output timing calculating part that refers to the change timing of a rectangular wave voltage recorded in a recording part while being previously associated with the voltage phase angle command value, determines whether a voltage phase angle of an output voltage of an inverter is a voltage phase angle of the change timing for each control period longer than the fixed period, calculates a difference value between the voltage phase angle command value and the voltage phase angle of the change timing, and calculates a changed count value obtained by integrating a count value counted by the counter in one period of the control period to a ratio between the difference value and a voltage phase angle corresponding to one period of the control period; and a rectangular-wave generating part for changing a state of a rectangular-wave voltage after the counting of an amount of the changed count value from the voltage phase angle of the change timing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motor control device and a motor control method using pulse control of an inverter.

  When motor control is performed in a high rotation region, the back electromotive force becomes large, and power supply voltage is insufficient in PWM (Pulse Width Modulation) control. Therefore, it is necessary to perform rectangular wave control. Since the amplitude is fixed in the rectangular wave control, the torque is controlled by controlling the phase of the output voltage of the inverter. Therefore, the phase accuracy of the output voltage is important in the rectangular wave control.

  However, in recent motor control, a microcomputer or the like is used, and the rectangular wave is controlled by discrete signal processing. Therefore, the phase of the output voltage is adjusted based on the output voltage command value at timings other than the control cycle (machine cycle, etc.). I can't control it. Therefore, even if you want to change the output voltage command value outside the control cycle, you must wait until the next control cycle timing, so you cannot control the phase of the output voltage according to the output voltage command value. There is a problem that an error occurs and the torque control performance is degraded.

  Therefore, in order to reduce the phase error of the output voltage, generally, a method of increasing the phase accuracy of the output voltage of the rectangular wave control by shortening the control cycle is employed. However, if the control cycle is shortened, the calculation load of the microcomputer increases, so that it is necessary to replace the microcomputer with a high processing performance and the cost of the apparatus increases.

  Patent Document 1, Patent Document 2, and the like have been proposed.

JP-A-4-222466 JP-A-5-146163

  A motor control device and a motor control method for realizing high-accuracy torque control by outputting a voltage according to a command value without shortening the control cycle during rectangular wave control, which has been made in view of the above circumstances. The purpose is to provide.

A motor control device including an inverter that controls a motor, which is one aspect, includes a voltage phase control unit, an internal counter, an output timing calculation unit, and a rectangular wave generation unit.
The voltage phase control unit calculates a voltage phase angle command value for each control period. The internal counter counts with a cycle shorter than the control cycle.

  The output timing calculation unit includes a voltage phase control unit that calculates a voltage phase angle command value, a counter that counts at a constant period, and a change in a rectangular wave voltage that is recorded in advance in association with the voltage phase angle command value in the recording unit. Referring to the timing, it is determined whether the voltage phase angle of the output voltage of the inverter is the voltage phase angle of the change timing every control cycle longer than the fixed cycle, and the voltage phase angle command value and the change timing are determined. The difference between the voltage phase angle and the voltage phase angle corresponding to one cycle of the control cycle is integrated with the count value counted by the counter in one cycle of the control cycle. Calculate the count value.

The rectangular wave generator changes the state of the rectangular wave voltage after counting the change count value from the voltage phase angle at the change timing.
With the above configuration, it is possible to output a voltage according to the command value without shortening the control cycle during rectangular wave control, and to realize highly accurate torque control.

  The voltage phase control unit obtains a torque difference value between a torque estimated value and a torque command value calculated based on a three-phase AC current value, a voltage command value, and a motor angular velocity, which are outputs of the inverter, in a torque calculation unit. Then, the voltage phase angle command value is calculated based on the moving position of the motor and the torque difference value.

  Further, the motor control device is further provided with a PWM control unit that performs PWM control of the inverter, and the PWM control unit controls the motor when it is determined that the PWM control is necessary according to the operating condition of the motor.

  The voltage can be output according to the command value without shortening the control cycle during the rectangular wave control, and high-accuracy torque control can be realized.

It is a figure which shows a motor control apparatus. It is a block diagram which shows the drive control system of a motor. It is a figure which shows the flowchart and data table which show operation | movement of the drive control system of a motor. It is a time chart which shows operation | movement of the drive control system of a motor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Example 1
FIG. 1 is a diagram showing a motor control device. The motor control device includes an inverter 2, a control unit 3, a drive unit 4, and a recording unit 5, and controls the motor 1 (M). For example, the motor 1 is a permanent magnet synchronous motor, and is driven using electric power supplied from a power source via the inverter 2. Further, the power source is not particularly limited, but is a battery, for example.

  The motor 1 is connected to an AC output terminal of the inverter 2 controlled by the control unit 3 and is driven by an AC current (U phase, V phase, W phase) output from the AC output terminal of the inverter 2. The motor 1 is not limited to a permanent magnet synchronous motor, and may be an AC motor. A synchronous machine including a permanent magnet synchronous motor and a synchronous reluctance motor is desirable, but an induction motor may be used. Moreover, it is not limited to a rotary electric machine, Electric motors, such as a linear motor, may be sufficient.

  The inverter 2 is configured by connecting two sets of switching elements (for example, IGBT (Insulated Gate Bipolar Transistor)) connected in series with each other in parallel to a DC power source via a capacitor. Then, when each switching element of the inverter 2 is turned on / off, an alternating current is output from each connection point (U phase, V phase, W phase) of the switching element.

  The control unit 3 is hardware that controls the motor 1. For example, you may comprise using CPU, DSP, and a programmable device. The drive unit 4 outputs a drive signal for turning on / off each switching element of the inverter 2 by PWM control. The control unit 3 acquires a signal (analog signal) output from a sensor or the like by converting it into a digital signal using an A / D converter, and uses it when executing a process described later.

The recording unit 5 is connected to the control unit 3 and includes a memory such as a ROM and a RAM. Programs and data for controlling the motor 1 are recorded therein.
FIG. 2 is a block diagram showing a drive control system of the motor 1. The drive control system includes a control switching unit 6, current sensors 7 a and 7 b, a PWM control unit 8, a rectangular wave control unit 9, a position detection unit 16, and an angular velocity calculation unit 17.

  The control switching unit 6 switches between the PWM control unit 8 and the rectangular wave control unit 9 based on the rotation speed of the motor 1. For example, the motor 1 is controlled by the PWM control unit 8 when the rotation speed of the motor 1 is in a low speed region, and the motor 1 is controlled by the rectangular wave control unit 9 when it is in a high speed region. Note that switching may be performed based on physical quantities such as a current phase angle and a voltage modulation rate calculated from a motor rotation speed, a rotation angle UVW phase current value, a UVW phase voltage command value, and the like.

  The current sensors 7 a and 7 b are provided on the U-phase line and the W-phase line of the three UVW-phase lines connecting the inverter 2 and the motor 1, and the U-phase current (Iu), which is the output current of the inverter 2, and W The phase current (Iw) is measured.

The PWM control unit 8 includes a torque / dq command calculation unit 10, a current value subtraction unit 11, a current control unit 12, a dq / UVW conversion unit 13, a PWM generation unit 14, and a UVW / dq conversion unit 15.
The torque / dq command calculation unit 10 generates a d-axis current command value Id ^* and a q-axis current command value Iq ^* based on the torque command value Tref. For example, torque / dq conversion is performed using a table in which the torque command value Tref, the d-axis current command value Id ^* , and the q-axis current command value Iq ^* created in advance recorded in the recording unit 5 are associated with each other.

The current value subtraction unit 11 includes a d-axis current value subtraction unit and a q-axis current value subtraction unit. The d-axis current value subtraction unit calculates a difference value between the d-axis current command value Id ^* and the d-axis current value Id output from the UVW / dq conversion unit 15. Similarly, the q-axis current value subtraction unit calculates a difference value between the q-axis current command value Iq ^* and the q-axis current value Iq output from the UVW / dq conversion unit 15.

Current control unit 12, and generates a d-axis voltage command value Vd ^* based on the difference value calculated in the d-axis current value subtraction unit. A q-axis voltage command value Vq ^* is generated based on the difference value calculated by the q-axis current value subtraction unit. For example, a PI deviation with a predetermined gain is calculated for a difference value corresponding to the d-axis and the q-axis to calculate a control deviation, and a d-axis voltage command value Vd ^* and a q-axis voltage command value Vq ^* are generated based on the control deviation. May be.

The dq / UVW conversion unit 13 monitors the d-axis and q-axis control voltage command values (Vd ^* , Vq ^* ) while monitoring the mover position θ of the motor 1, the U-phase, V-phase, and W-phase voltage command values. Convert to (Vu ^* , Vv ^* , Vw ^* ).

The PWM generator 14 and the drive unit 4 generate PWM signals Vu, Vv, and Vw for each phase according to the UVW phase voltage command values Vu ^* , Vv ^* , and Vw ^* . The motor current supplied to each phase of the permanent magnet synchronous motor 1 is determined by the duty of the corresponding PWM signal Vu, Vv, Vw.

  The UVW / dq converter 15 converts the detected value of the motor current supplied to the motor 1 into a d-axis / q-axis current value while monitoring the output of the position detector 16 with respect to the slider position θ of the motor 1. Here, the U-phase current Iu and the W-phase current Iw detected using the current sensors 7a and 7b are converted into a d-axis current value Id and a q-axis current value Iq. The d-axis current is a so-called field current and is a current vector component for generating a field. The q-axis current is a so-called torque current and is a current vector component for generating torque.

The position detection unit 16 detects the mover position θ of the rotor of the motor 1.
The angular velocity calculation unit 17 calculates the angular velocity ω of the motor 1 based on the mover position θ detected by the position detection unit 16.

The rectangular wave control unit 9 includes a torque calculation unit 18, a torque value subtraction unit 19, a voltage phase control unit 20, an output timing calculation unit 21, an internal counter 22, and a rectangular wave generation unit 23.
The torque calculation unit 18 generates a V-phase current Iv from the U-phase current Iu and the W-phase current Iw, and outputs the angular velocity measurement value ω, the UVW phase currents Iu, Iv, Iw, and the efficiency η output from the angular velocity calculation unit 17. Based on Formula 1, a torque estimate value Test is generated.

Test = (Vu ^* × Iu + Vv ^* × Iv + Vw ^* × Iw) × η / ω (Formula 1)
Vu ^* , Vv ^* , Vw ^* : UVW phase voltage command value [V]
Iu, Iv, Iw: current detection value of UVW phase [A]
ω: Angular velocity measurement value [rad / sec]
η: Efficiency

The torque value subtraction unit 19 calculates a difference between the torque command value T _ref and the estimated torque value T _est to calculate a torque difference value T _sub .

The voltage phase control unit 20 calculates a voltage phase angle command value for each control period. For example, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are generated based on the torque difference value T _sub . Further, the d-axis voltage command value Vd ^* , the q-axis voltage command value Vq ^*, and the mover position θ that is the output of the position detector 16 are acquired, and the voltage phase angle command value φ _ref is calculated according to Equation 2. Further, the current voltage phase angle φ is calculated based on the moving element position θ.

φref = θ + tan ⁻¹ (−Vq / Vd) (Formula 2)

The voltage phase control unit 20 may acquire the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* from the output of the current control unit 12. In this case, since the processing in the torque calculation unit 18 and the torque value subtraction unit 19 and the processing for calculating the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^{* in} the voltage phase control unit 20 are eliminated, the circuit scale or program The scale can be reduced.

The output timing calculation unit 21 calculates a change count value ΔT that generates a rectangular wave at a timing other than the control period, based on a voltage phase angle command value φ _ref described later and a count value T output from the internal counter 22. Here, the control cycle is, for example, a machine cycle.

For example, it is determined that the change timing is reached when the following Expression 3 is satisfied. Δφ is the difference between the voltage phase angle phi _i and voltage phase angle phi _i acquired during the voltage phase angle command value φ _{ref (i).}

φ ₁ <Δφ <φ ₂ (Equation 3)
φ ₁ : voltage phase angle corresponding to 1 control cycle φ ₂ : 2 × φ ₁ (voltage phase angle corresponding to twice control cycle)

Next, when it is the change timing, the first difference value between the voltage phase angle command value and the voltage phase angle at the change timing is calculated, and the voltage phase angle and change timing obtained one cycle before the change timing are calculated. A second difference value from the voltage phase angle acquired two cycles ago is calculated. The change count value is calculated by adding the count value corresponding to the control cycle counted by the internal counter to the ratio between the first difference value and the second difference value.

  The internal counter 22 is a counter that counts at a cycle shorter than the control cycle Ts of the motor 1 used in PWM control or rectangular wave control. The internal counter 22 may use an internal counter such as a CPU, or may be provided outside the CPU.

The rectangular wave generator 23 generates a rectangular wave signal for turning on and off each switching element of the inverter 2 based on the change count value ΔT and the count value T corresponding to the control period of the change timing. Change the voltage state.
(Description of operation)
The operation will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the motor drive control system and a data table. FIG. 4 is a time chart showing the operation of the motor drive control system. The vertical axis of FIG. 4 shows the output voltage command value, the acquisition timing of the voltage phase angle command value, the conventional output voltage, the internal counter, and the output voltage, and the horizontal axis shows the time and count value.

In step S <b> 1, the torque value subtraction unit 19 of the control unit 3 calculates the torque command value T _ref recorded in the recording unit 5 and the estimated torque value T _est calculated by the torque calculation unit 18 and recorded in the recording unit 5. The torque difference value Tsub (= torque command value T _ref -torque estimated value T _est ) is generated and recorded in a register such as the recording unit 5 or the CPU (see A in FIG. 3).

In step S2, the voltage phase control unit 20 of the control unit 3 generates the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* based on the torque difference value T _sub recorded in the recording unit 5. Further, the d-axis voltage command value Vd ^* , the q-axis voltage command value Vq ^*, and the moving element position θ are acquired, and the voltage phase angle command value φ _ref is calculated according to Equation 2 and recorded in the recording unit 5 or a register such as a CPU. (See B in FIG. 3).

In step S3, the output timing calculation unit 21 of the control unit 3 records a count value for each control cycle in order to record how many counts the internal counter 22 can count within a preset control cycle. For example, the values T _i−1 and T _i counted by the internal counter 22 are acquired at the timings T2 and T3 shown in FIG. When the internal counter 22 counts from T _i−1 to T _i (control cycle), the count value becomes Ts. Therefore, Ts is recorded as a count value in the recording unit 5 or a register such as a CPU. Since the control cycle is a fixed cycle, the count value Ts may be calculated and recorded in advance.

Further, the output timing calculation unit 21 acquires the voltage phase angle command value φ _ref . In FIG. 4, φ _i−2 is acquired by timing T1, φ _i−1 is acquired by timing T2, φ _i is acquired by timing T3, and φ _{i + 1} is acquired by timing T4.

Then, it is determined whether the change timing of each post timing acquisition voltage phase angle command value phi _ref, the voltage command value of UVW phase compared to condition angular value range (φ1 <Δφ <φ2).
In the case of FIG. 4, when it is determined that the voltage phase angle φ _i is the change timing, a change count value ΔT indicating the change timing is calculated according to Equation 4 (see C in FIG. 3), and the rectangular wave generator 23 Forwarded to

ΔT = ((φ _{ref (i)} −φ _i ) / (φ _i−2 −φ _i−1 )) × (T _i −T _i−1 ) (Formula 4)

In FIG. 4, when the voltage phase angle φ _i at the timing T3 is calculated, the calculated voltage phase angle command value φ _ref is φ _{ref (i)} , and φ _ref calculated by φ _i−1 is φ _{ref (i−1)} .

  In step S4, the rectangular wave generator 23 generates a rectangular wave signal Vref to be supplied to the inverter 2 based on the change timing ΔT and the count value Ti (see D in FIG. 3). In FIG. 4, since the count value Ti is associated with the timing T3, the rectangular wave generator 23 counts from the timing T3 to the change count value ΔT and changes the voltage level from the low level to the high level at the timing Ta. When the voltage level is changed from the high level to the low level (timing Tb), for example, the voltage phase angle command value φi may be set to change from the high level to the low level when it changes by 180 degrees. Good.

  By doing the above, the calculated output voltage change timing is counted by the internal counter and the voltage is output, so that the voltage is output according to the command value without shortening the control cycle during rectangular wave control, Accurate torque control can be realized.

  Since the count cycle of the internal counter 22 is shorter than the PWM control cycle or the control cycle of the motor 1 for rectangular wave control, the voltage is output with reference to the count value of the internal counter 22 so that it can be used at other times than the control timing. The output voltage can be changed.

  Since the internal timer is generally mounted in the CPU or microcomputer, the present invention can be realized by using a timer that counts in a cycle shorter than the control cycle even if it is not the internal counter of the CPU or microcomputer. be able to.

  The proposed method is not limited to the rectangular wave control used in the high-speed rotation region, but can be realized in other motor controls such as PWM control and V / f control used in the low / medium speed region. Is possible.

Note that it is not necessary to replace the microcomputer with high processing performance, and the cost of the apparatus can be reduced.
The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

1 motor,
2 inverter,
3 Control unit,
4 Drive unit,
5 Recording section,
6 Control switching part,
7a, 7b current sensor,
8 PWM controller,
9 Rectangular wave control unit,
10 Torque / dq command calculation unit,
11 Current value subtraction part,
12 Current controller,
13 dq / UVW converter,
14 PWM generator,
15 UVW / dq converter,
16 position detector,
17 Speed calculator,
18 Torque calculator,
19 Torque value subtraction part,
20 voltage phase controller,
21 output timing calculation section,
22 Internal counter,
23 rectangular wave generator,

Claims (5)

A motor control device including an inverter for controlling a motor,
A voltage phase controller that calculates a voltage phase angle command value, a counter that counts at a constant period,
With reference to the change timing of the rectangular wave voltage recorded in advance in the recording unit in association with the voltage phase angle command value, the voltage phase angle of the output voltage of the inverter is changed every control cycle longer than the certain cycle. And calculating a difference value between the voltage phase angle command value and the voltage phase angle at the change timing, and a voltage phase angle corresponding to one cycle of the control cycle, An output timing calculation unit that calculates a change count value obtained by integrating a count value counted by the counter in one cycle of the control cycle in the ratio of
A rectangular wave generator for changing the state of the rectangular wave voltage after counting the change count value from the voltage phase angle of the change timing;
A motor control device comprising: The voltage phase controller is
Obtaining a torque difference value between a torque command value and a torque estimation value calculated based on a three-phase alternating current value, a voltage command value, and a motor angular velocity, which are outputs of the inverter;
The motor control device according to claim 1, wherein the voltage phase angle command value is calculated based on a position of the moving element of the motor and the torque difference value.   The motor control device further includes a pulse modulation control unit that performs pulse modulation control of the inverter. When it is determined that switching to pulse modulation control is necessary based on the current phase angle or voltage modulation rate, the pulse modulation control unit The motor control apparatus according to claim 1, wherein the motor is controlled.   The motor control device according to claim 3, wherein when it is determined that the rotation speed of the motor is slower than a rotation speed recorded in advance, the pulse modulation control unit controls the motor. A motor control method comprising an inverter for controlling a motor,
Calculate the voltage phase angle command value,
With reference to the change timing of the rectangular wave voltage recorded in advance in the recording unit in association with the voltage phase angle command value, the voltage phase angle of the output voltage of the inverter for each control period longer than a predetermined constant period Is a voltage phase angle at the change timing, and calculates a difference value between the voltage phase angle command value and the voltage phase angle at the change timing,
Calculating a change count value obtained by integrating a count value counted by the counter in one cycle of the control cycle to a ratio between the difference value and a voltage phase angle corresponding to one cycle of the control cycle;
Change the state of the rectangular wave voltage after counting the change count value from the voltage phase angle of the change timing,
The motor control method characterized by the above-mentioned.

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