JP5407221B2 - Synchronous motor drive control device - Google Patents

Description

  The present invention relates to a synchronous motor drive control device that drives, for example, a permanent magnet type synchronous motor (PM motor) with an inverter.

  Generally, in an apparatus for controlling a synchronous motor, an inverter is used to control a current supplied to the winding of the synchronous motor. The motor current supplied to each phase of the synchronous motor winding is detected by a current detection circuit, and the inverter is controlled based on the detected current to control the torque, speed, position, etc. of the synchronous motor. (Patent Documents 1 and 2, etc.).

  Further, in this type of control device, in order to drive the synchronous motor at a specified speed (number of revolutions), a deviation for detecting the number of revolutions of the synchronous motor and obtaining a deviation from the command speed (number of revolutions). A voltage control system including a calculating means and a proportional integrator is configured.

JP 2001-275382 A JP 2000-324883 A

  Here, the gain (proportional constant and integral time constant) of the proportional integrator used in the voltage control system is set as a fixed value on the assumption that the motor constant does not change depending on operating conditions. The constant is a fixed value.

  However, when a large current is passed through the stator side winding, such as when the ratio of the continuous rated torque to the short-time rated torque is large, as in a PM motor, magnetic saturation is likely to occur in this winding portion, and the motor The constant will also change greatly. Therefore, if the constant of the proportional integrator is controlled with a fixed value, if the number of rotations of the PM motor increases and the induced voltage becomes high, correction with the constant so far is corrected with high sensitivity, so hunting is caused in the proportional integrator. There was a fear.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and a synchronous motor drive control device that enables voltage control by preventing hunting in a proportional integrator even when the rotational speed of the synchronous motor is increased. The purpose is to provide.

In order to achieve the above-described object, the configuration of the synchronous motor drive control device adopted by the present invention includes an inverter that generates a drive current corresponding to an input control signal and supplies the drive current to the synchronous motor, and a rotational speed of the synchronous motor A proportional-integral calculating means for generating a control signal by performing a proportional-integral calculation on a command speed signal for instructing, a rotational speed detecting means for detecting the rotational speed of the synchronous motor, and a proportional constant and an integral of the proportional-integral calculating means time constant, said rotational speed of the rotational speed detecting means has detected is set to a predetermined value when it does not exceed a predetermined base speed, when the rotation speed that exceeds the base speed is the predetermined characterized by comprising a constant variable means a value smaller than the value set to the smaller value as the rotational speed increases, the.

With the above configuration, the constant variable means can change the proportional constant and the integration time constant of the proportional-integral calculation means when the rotational speed of the synchronous motor exceeds a predetermined base rotational speed than when it does not exceed the base rotational speed. Set to a smaller value.
Thereby, the synchronous motor drive control device can slow down the correction sensitivity with respect to fluctuations in the rotation of the synchronous motor, and can prevent hunting in the proportional-integral calculation means.

In the above-described configuration, the constant varying means is configured to set the proportional constant and the integration time constant of the proportional-integral computing means to the predetermined value when the rotational speed detected by the rotational speed detecting means exceeds the base rotational speed. It is preferable to set the values to be smaller and different from each other and become smaller as the number of rotations increases .

  The synchronous motor drive control device according to the present invention reduces the constant of the proportional integration means by the constant variable means when the rotational speed of the synchronous motor exceeds a predetermined base rotational speed than when the rotational speed of the synchronous motor does not exceed the basic rotational speed. Even when the rotational speed of the synchronous motor is increased, hunting can be prevented by reducing the correction sensitivity of the proportional-integral calculating means.

<Embodiment>
FIG. 1 is a block diagram showing a synchronous motor drive control device according to this embodiment.
A synchronous motor drive control device (hereinafter referred to as a control device) 30 includes an inverter 10 that is PWM-controlled. The inverter 10 is connected to a direct current power source (not shown) and is controlled in operation by a control signal to supply a three-phase drive current to the PM motor 101.

The control device includes a q-axis command current generator 11q that receives a command torque signal and generates a q-axis command current signal, a d-axis command current generator 11d that receives a command speed signal and generates a d-axis command current signal, Is provided.
A proportional integrator 13q is connected to the subsequent stage of the q-axis command current generator 11q via a deviation calculator 12q, and a proportional integrator is connected to the subsequent stage of the d-axis command current generator 11d via a deviation calculator 12d. 13d is connected, and the proportional integrators 13q and 13d generate separated control signals. Further, in the subsequent stage of the proportional integrators 13q and 13d, a coordinate converter 14A that converts the control signal into two-phase to three-phase, and a PWM that converts the three-phase control signal from the coordinate converter 14A into a PWM waveform using a reference wave. The waveform generator 15 is connected.
The proportional integrators 13q and 13d perform proportional integral (PI) calculations on the deviations of the q-axis current and the d-axis current, respectively.

  The deviation calculation units 12q and 12d subtract the q-axis and d-axis detection current signals from the q-axis and d-axis command current signals. The q-axis and d-axis detection current signals are detected by a current detection unit 16 that detects the current value of the drive current supplied from the inverter 10 to the PM motor 101, and the coordinate conversion unit 14B performs three-phase to two-phase conversion on the detection signal. It is obtained by converting into two phases. The q-axis and d-axis detection current signals are input to the deviation calculation units 12q and 12d, and become feedback signals for the q-axis and d-axis command current signals.

On the other hand, a deviation calculation unit 17 is connected to the input end of the command speed signal that is the command rotation speed. The deviation calculation unit 17 subtracts the detection voltage signal that is a feedback signal from the command speed signal, and proportionally outputs this signal. Output to the integrator 21. This detection voltage signal is detected by the voltage detection unit 18 in the voltage value of the drive current supplied from the inverter 10 to the PM motor 101, and this detection signal is converted into two phases by the coordinate conversion unit 14C that performs three-phase to two-phase conversion. Above, it is obtained as a scalar quantity by the arithmetic expression (√ (Vd ² + Vq ² )) in the arithmetic unit 19.

The detection voltage signal Vq, Vd inputted to the arithmetic unit 19, but also of a is calculated from the voltage supplied from the actual inverter 10 by the voltage detection unit 18 to the PM motor 101, as indicated by a dotted line The output voltages from the proportional integrators 13q and 13d may be detected as detection voltage signals Vq and Vd.

  A reference phase signal for coordinate conversion in the coordinate conversion units 14A to 14C is obtained by an angle detection unit 20 including a rotary encoder that detects the rotor position of the PM motor 101, an inertial sensor, a surface acoustic wave sensor, a gyro sensor, a resolver, and the like. It is done.

  Further, the proportional integrator 21 connected to the subsequent stage of the deviation calculating unit 17 performs a proportional integral (PI) calculation with a gain (proportional constant and integral time constant) on the deviation between the command speed signal and the detected voltage signal, thereby obtaining a target speed. Generate a signal. This target speed signal is output to the d-axis command current generator 11d.

  In the control device 30, drive control of the PM motor 101 is realized according to the command torque signal and the command speed signal (speed).

  Next, features of the present embodiment will be described. The feature of this embodiment is that a constant variable proportional integration unit 31 including a proportional integrator 21 is provided. The proportional integrator 21 is proportionally integrated by a proportional constant and an integration time constant (hereinafter referred to as a constant). Hereinafter, in this embodiment, the proportionality constant is referred to as P gain, and the integration time constant is referred to as I gain.

  A differentiator 32 connected to the output side of the angle detection unit 20 is connected to the input side of the constant variable proportional integration unit 31, and the PM motor 101 obtained by differentiating the angle detected by the angle detection unit 20. (That is, the rotation speed B) is input.

  The constant variable proportional integration unit 31 includes a proportional integrator 21 and a divider 33, a limiter table 34, and multipliers 35P and 35I for changing the constant of the proportional integrator 21, and the divider 33 and the limiter table. 34 and multipliers 35P and 35I constitute constant variable means according to the present invention.

  The divider 33, the limiter table 34, and the multipliers 35P and 35I are shown in a block diagram for convenience, but are performed by program processing by a microcomputer comprising a CPU, ROM, and RAM.

The divider 33 calculates the magnification α using the base rotation speed A stored in advance as the numerator and the input rotation speed B as the denominator. The base rotational speed A is set to about 20% to 70% of the rated rotational speed of the PM motor 101, for example.
The limiter table 34 is a graph in which the rotation speed B is plotted on the horizontal axis and the magnification α is plotted on the vertical axis, and is used to keep the magnification α at 1 until the rotation speed B reaches the base rotation speed A.
The multiplier 35P is a circuit that multiplies a P (proportional) gain stored in advance in a storage unit (not shown) by a magnification α, and the multiplier 35I includes a prestored I (integral) gain (integral). This is a circuit for multiplying a time constant) by a magnification α.

  In the constant variable proportional integration unit 31 in this embodiment, the rotational speed B of the PM motor 101 output from the differentiator 32 is monitored, and the magnification α is the limiter until the rotational speed B reaches the base rotational speed A. It is “1” because it is regulated by the table 34. The proportional integrator 21 performs calculation using the P gain and I gain stored in advance. That is, the proportional integrator 21 performs a proportional integration (PI) operation on the voltage signal obtained by subtracting the detected voltage signal that is a feedback signal from the command speed signal.

On the other hand, when the rotation speed B exceeds the base rotation speed A, the magnification α is not regulated by the limiter table 34 and is calculated by an arithmetic expression (α = A / B) by the divider 33. That is, at the stage where the rotation speed B exceeds the base speed A, the magnification will decrease with an increase in rotational speed B. The multiplier 35P sets the value obtained by multiplying the P gain by the magnification α as the P gain, and the multiplier 35I sets the value obtained by multiplying the I gain by the magnification α as the I gain, thereby rotating the constant of the proportional integrator 21. The number B is decreased as compared with a case where the number B does not exceed the base rotation number A. The proportional integrator 21 performs a proportional integration (PI) operation using the P gain and the I gain multiplied by the multipliers 35P and 35I.

  In the constant variable proportional integration unit 31 according to the present embodiment, until the rotational speed B exceeds the base rotational speed A, the magnification is set to “1” and the proportional integrator 21 is used using the P gain and I gain stored in advance. Therefore, it is possible to perform signal correction with high accuracy against fluctuations in the rotation of the PM motor 101.

On the other hand, when the rotational speed B exceeds the base rotational speed A, the gain of the proportional integrator 21 is decreased as the rotational speed B increases. Can be slowed to prevent hunting in the proportional integrator 21.
As a result, the control device 30 enables speed (rotation speed) control by the proportional integrator 21 even when the PM motor 101 rotates at the base rotation speed A or higher.

In the embodiment, the constant variable proportional integration unit 31 sets the magnification α to a value smaller than “1” by the divider 33 and the limiter table 34 when the rotational speed B exceeds the base rotational speed A. However, the present invention is not limited to this, and is controlled using a map in which the magnification α is determined in advance with respect to the rotational speed B, or a value with a slope of “−” is determined instead of the divider 33. Alternatively, it may be controlled using an arithmetic unit of a linear function. Further, the magnification α multiplied by the P gain and the I gain may be individually different. In short, the constant variable means may be a means for reducing the coefficient k as the rotational speed B increases when the rotational speed B exceeds the base rotational speed A.
On the other hand, the proportional integrator 21 is not limited to a proportional integrator, and may be an amplifier combined with differentiation.

  Furthermore, although the case where the PM motor is used as the synchronous motor is illustrated in the above embodiment, the present invention is not limited to this, and an embedded magnet synchronous motor (IPM motor) in which a permanent magnet is embedded in the rotor may be used. . In this case, a d-axis command signal is supplied from the d-axis command current generator 11d to the q-axis command current generator 11q.

It is a block diagram which shows the synchronous motor drive control apparatus by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inverter, 11q ... q-axis command current generation part, 11d ... d-axis command current generation part, 12q, 12d, 17 ... Deviation calculation part, 13q, 13d ... Proportional integrator, 14, 14A, 14B, 14C ... Coordinate conversion , 15 ... PWM waveform generation unit, 16 ... current detection unit, 18 ... voltage detection unit, 20 ... angle detection unit, 21 ... proportional integrator (proportional integral calculation means), 30 ... synchronous motor drive control device (control device) 31 ... constant variable proportional integration unit, 32 ... differentiator, 33 ... divider (constant variable means), 34 ... limiter table (constant variable means), 35P, 35I ... multiplier (constant variable means), 101 ... PM motor .

Claims (2)

An inverter that generates a drive current corresponding to an input control signal and supplies the drive current to the synchronous motor;
Proportional-integral calculation means for generating a control signal by performing a proportional-integral calculation on a command speed signal instructing the rotational speed of the synchronous motor;
A rotational speed detection means for detecting the rotational speed of the synchronous motor;
The proportionality constant and the integration time constant of the proportional-integral calculating means are set to a predetermined value when the rotational speed detected by the rotational speed detecting means does not exceed a predetermined base rotational speed, and the rotational speed is set to the base rotational speed. synchronous motor drive control device when that exceeds the number which is characterized by comprising a constant variable means for setting the smaller value as the rotational speed increases to a value smaller than the predetermined value. 2. The synchronous motor drive control device according to claim 1, wherein the constant variable means includes a proportionality constant and an integration time constant of the proportional-integral calculation means, wherein the rotational speed detected by the rotational speed detection means exceeds the base rotational speed. The synchronous motor drive control device is characterized in that each is set to a value that is smaller than the predetermined value and different from the predetermined value and that decreases as the rotation speed increases .

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