JP2006025541A - Drive controller of motor and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the drive controller of a motor and its control method for improving the power efficiency and achieving a high-performance control, even if the effect of an on-delay time due to a large load and a low rotation speed can not ignored. <P>SOLUTION: The drive controller of the motor 15 is provided with a current direction sensor 20 for detecting positive and negative signs of a three-phase armature current of the motor, an on-delay compensating voltage estimating means 18 for inputting the positive and negative signs of the three-phase armature current and outputting a three-phase on-delay compensating voltage, and an adding means 19 for adding the three-phase on-delay compensating voltage to an AC three-phase voltage instruction and outputting new AC three-phase voltage instruction to a PWM inverter 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for controlling a motor with high performance and high efficiency using an inexpensive current direction sensor.

In general, high-performance control of an electric motor performs speed (or position) control based on a rotor position signal detected by a position sensor while performing current control based on an armature current signal detected by a current sensor. On the other hand, since the motor drive system is required to be low in price, we want to use inexpensive sensors or reduce the number of sensors.
Conventionally, a control system is configured using an estimated current value without using a current sensor (see, for example, Non-Patent Document 1).
FIG. 2 is a block diagram showing a configuration of a conventional motor drive control device.
In FIG. 2, 11 is a control compensator, which calculates d and q-axis voltage commands v _dr and v _qr based on the speed deviation ω _err , the rotor speed ω _m and d, and the q-axis estimated currents i _ds and i _qs. To do. _{Reference numeral} 12 denotes a current estimator, which calculates d and q axis estimated currents i _ds and i _qs based on d and q axis voltage commands v _dr and v _qr . Reference numeral 13 denotes a dq / 3-phase AC coordinate converter, which calculates three-phase voltage commands v _ur , v _vr , and v _wr based on d and q-axis voltage commands v _dr and v _qr and the rotor position θ _m . A PWM inverter 14 outputs three-phase voltages v _u , v _v , and v _w based on the three-phase voltage commands v _ur , v _vr , and v _wr to drive the motor 15.
When the on-delay time is sufficiently short and the effect is small, the voltage command is the same as the drive system of a normal motor without using a current sensor because the estimated voltage matches the input voltage of the motor and the estimated current. Thus, a stable and high-performance control system can be configured.
As described above, the motor control device according to the prior art estimates the current based on the voltage command and constitutes the control system.
Shigeo Morimoto, 2 others, “Current Sensorless Drive System for Synchronous Motor Using Only Low-Resolution Position Sensor”, The Institute of Electrical Engineers of Japan, Journal of the Institute of Electrical Engineers of Japan, 2001 (Vol. 121, No. 11, p. 1126-1133

Because the conventional motor drive control system ignores the effects of on-delay and configures the control system, when the load is heavy and the rotation speed is low, the voltage command is estimated as the input voltage of the motor due to the effect of on-delay time. Since the current deviates from the armature current, the characteristics of the control system are not as designed and deteriorated. In addition, the non-interference compensation cannot be performed accurately, the d-axis current is increased, and the power efficiency is poor.
The present invention has been made in view of such problems, and by constructing a control system that compensates for the influence of on-delay, a drive control device for an electric motor that can perform high-performance control with high power efficiency and the control system thereof An object is to provide a control method.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 is a position sensor that detects a rotor position of an electric motor, a differentiating unit that differentiates the rotor position and outputs a rotor speed of the electric motor, and a speed command based on the rotor speed. Subtracting means for obtaining a speed deviation by subtraction, control compensation means for inputting the speed deviation, the rotor speed, the d-axis estimated current and the q-axis estimated current and outputting a d-axis voltage command and a q-axis voltage command; Current estimation means for inputting the d-axis voltage command and the q-axis voltage command and outputting the d-axis estimated current and the q-axis estimated current; the d-axis voltage command, the q-axis voltage command, and the rotor position; Current sensorless control device comprising: coordinate conversion means for inputting an AC three-phase voltage command to a PWM inverter; and a PWM inverter for receiving the three-phase voltage command and outputting a three-phase voltage for driving the motor In,
A current direction sensor for detecting the sign of the three-phase armature current of the motor;
On-delay compensation voltage estimation means for inputting a positive / negative sign of the three-phase armature current and outputting a three-phase on-delay compensation voltage;
And adding means for outputting a new AC three-phase voltage command obtained by adding the three-phase on-delay compensation voltage to the AC three-phase voltage command to the PWM inverter.
The invention according to claim 2 is the result of the invention according to claim 1, wherein the on-delay compensation voltage estimation means inputs a positive / negative sign of the three-phase armature current and provides an on-delay time. The absolute value of the difference between the input voltage and the output voltage of the PWM inverter is added with the sign of the three-phase armature current to make the three-phase on-delay compensation voltage.
According to a third aspect of the present invention, there is provided a position sensor for detecting a rotor position of an electric motor, a differentiation means for differentiating the rotor position and outputting a rotor speed of the electric motor, and a speed command for the rotor. Subtracting means for subtracting by speed to obtain a speed deviation, and control compensation means for inputting the speed deviation, the rotor speed, the d-axis estimated current and the q-axis estimated current and outputting a d-axis voltage command and a q-axis voltage command Current estimation means for inputting the d-axis voltage command and the q-axis voltage command and outputting the d-axis estimated current and the q-axis estimated current, the d-axis voltage command, the q-axis voltage command, and the rotation Current sensorless comprising coordinate conversion means for inputting a child position and outputting an AC three-phase voltage command to the PWM inverter, and a PWM inverter for inputting the three-phase voltage command and outputting the three-phase voltage for driving the motor In the drive control method of the electric motor,
The sign of the three-phase armature current of the motor is detected by a current direction sensor,
The three-phase electric machine is added to the absolute value of the difference between the input voltage and the output voltage of the PWM inverter generated by inputting the positive / negative sign of the three-phase armature current to the on-delay compensation voltage estimation means and providing an on-delay time. The three-phase on-delay compensation voltage with the sign of the child current added,
The adding means outputs a new AC three-phase voltage command obtained by adding the three-phase on-delay compensation voltage to the AC three-phase voltage command to the PWM inverter.

  According to the present invention, the on-delay compensation voltage is calculated based on the direction of the armature current detected by using an inexpensive current direction sensor and added to the voltage command so that the voltage command matches the input voltage of the motor well. Therefore, it is possible to provide an electric motor drive control device and a control method thereof that can make the estimated current well match the armature current and perform stable and high-performance control. In addition, since more accurate non-interference compensation can be performed using an accurate estimated current, the power efficiency of the drive system can be improved by keeping the d-axis current small.

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

FIG. 1 is a block diagram of an electric motor drive control apparatus according to an embodiment of the present invention. In the figure, 11 is a control compensator, which calculates d and q-axis voltage commands v _dr and v _qr based on speed deviation ω _err , rotor speed ω _m and d, and q-axis estimated currents i _ds and i _qs. . _{Reference numeral} 12 denotes a current estimator, which calculates d and q axis estimated currents i _ds and i _qs based on d and q axis voltage commands v _dr and v _qr . Reference numeral 13 denotes a dq / 3-phase AC coordinate converter, which calculates three-phase voltage commands v _ur , v _vr , and v _wr based on d and q-axis voltage commands v _dr and v _qr and the rotor position θ _m . Reference numeral 18 denotes an on-delay compensation voltage estimator. The positive / negative of the three-phase armature current detected by the current direction sensor 20 in the absolute value of the difference between the input voltage and the output voltage of the PWM inverter caused by providing the on-delay time. A value _obtained by multiplying the signs S _ius , S _ivs , and S _iws is a three-phase on-delay compensation voltage Δv _us , Δv _vs , Δv _ws . Reference numeral 19 denotes an adder, which adds three-phase on-delay compensation voltages Δv _us , Δv _vs , Δv _ws to the three-phase voltage commands v _ur , v _vr , v _wr to give new three-phase voltage commands v _ur1 , v _vr1 , v _{Let wr1} . A PWM inverter 14 _outputs three-phase voltages v _u , v _v and v _w based on new three-phase voltage commands v _ur1 , v _vr1 and v _wr1 to drive the motor 15. Reference numeral 20 denotes a current direction sensor that detects the sign of the three-phase armature current.
The present invention differs from Non-Patent Document 1 in that it includes an on-delay compensation voltage estimator 18, an adder 19, and a current direction sensor 20. In addition, since the current direction sensor determines only the positive / negative of the current direction, it is simple and inexpensive.

Hereinafter, the operation principle of the control device of the present invention will be described.
In the PWM inverter, an on-delay time must be provided to prevent a short circuit of the DC bus. On the other hand, when the on-delay time is provided, the output voltage of the PWM inverter is different from the input voltage. The absolute value of the difference (herein referred to as the on-delay voltage constant) ΔV is ΔV = E _d · t _d · f _c (1)
It is represented by Where t _d is the on-delay time, E _d is the DC bus voltage, and f _c is the PWM carrier frequency. Also, the differences ΔV _u , ΔV _v , ΔV _w between the input voltage and the output voltage of the three-phase PWM inverter have different signs depending on the directions of the three-phase armature currents i _u , i _v , i _w , respectively. Assuming that the direction flowing into the motor is the positive direction of the current, when the current direction of a certain phase is positive, the difference between the input voltage and the output voltage of the PWM inverter of that phase is positive, and the current direction of a certain phase is negative At that time, the difference between the input voltage and the output voltage of the PWM inverter of that phase becomes negative.
Also, the sign function Sign (x) is

Defined as
ΔV _u = V _ur1 −V _u = Sign (i _u ) · ΔV (3)
ΔV _v = V _vr1 −V _v = Sign (i _v ) · ΔV (4)
ΔV _w = V _wr1 −V _w = Sign (i _w ) · ΔV (5)
It becomes.
On the other hand, the detection signal of the current direction sensor is S _ius = Sign (i _u ) (6)
S _ivs = Sign (i _v ) (7)
S _iws = Sign (i _w ) (8)
It becomes. Therefore, the three-phase on-delay compensation voltage is ΔV _us = Sign (i _u ) · ΔV (9)
ΔV _vs = Sign (i _v ) · ΔV (10)
ΔV _ws = Sign (i _w ) · ΔV (11)
It becomes.
From Formula (3) to Formula (5) and Formula (9) to Formula (11),
ΔV _us = ΔV _u = V _ur1 −V _u (12)
ΔV _vs = ΔV _v = V _vr1 −V _v (13)
ΔV _ws = ΔV _w = V _wr1 −V _w (14)
It becomes. Therefore, the three-phase voltage command is V _ur = V _ur1 −ΔV _us = V _u (15)
V _vr = V _vr1 -ΔV _vs = V _v (16)
V _wr = V _wr1 −ΔV _ws = V _w (17)
It becomes. That is, the d and q-axis voltage commands v _dr and v _qr coincide with the d and q-axis voltages of the motor. Therefore, the current estimated based on the d and q-axis voltage commands v _dr and v _qr matches the armature current.
Thus, by adding the on-delay compensation voltage calculated based on the sign of the armature current detected using an inexpensive current direction sensor to the voltage command, the voltage command is compensated for by the motor. The input voltage can be matched, and the current estimated based on this voltage command can be matched with the armature current. When stabilization compensation and non-interference compensation are performed using this estimated current, high-performance and high-efficiency control can be performed without using an expensive current sensor.

  Next, the effects of the present invention will be described using specific examples. The simulation results using the prior art and the technique of the present invention for the synchronous motor are shown in FIGS. 4 and 5, respectively. It can be seen that when the technique of the present invention is used, the estimated current agrees well with the armature current, the speed response follows the speed command better, and the d-axis current is smaller than when the conventional technique is used.

  Since the technique of the present invention can accurately estimate the current by compensating for the influence of on-delay, it can also be applied to control of other electromagnetic actuators using a PWM inverter.

The block diagram of the drive control apparatus of the electric motor which shows the Example of this invention The block diagram which shows the structure of the drive control apparatus of the motor of a prior art The figure which shows the simulation result of the speed control of the electric motor using a prior art The figure which shows the simulation result of the speed control of the electric motor using the technique of this invention

Explanation of symbols

10 subtractor 11 control compensator 12 current estimator 13 dq / 3-phase AC coordinate converter 14 PWM inverter 15 motor 16 position sensor 17 differentiator 18 on-delay compensation voltage estimator 19 adder 20 current direction sensor 181 on-delay Voltage constant 182 multiplier

Claims (3)

A position sensor for detecting the rotor position of the electric motor; a differentiation means for differentiating the rotor position to output the rotor speed of the electric motor; and a subtraction means for subtracting a speed command by the rotor speed to obtain a speed deviation. Control compensation means for inputting the speed deviation, the rotor speed, the d-axis estimated current and the q-axis estimated current and outputting a d-axis voltage command and a q-axis voltage command; and the d-axis voltage command and the q-axis Current estimation means for inputting a voltage command and outputting the d-axis estimated current and the q-axis estimated current; and the d-axis voltage command, the q-axis voltage command, and the rotor position are input, and an AC three-phase voltage command In a current sensorless control device comprising: coordinate conversion means for outputting a PWM inverter; and a PWM inverter that outputs the three-phase voltage for driving the motor by receiving the three-phase voltage command.
A current direction sensor for detecting the sign of the three-phase armature current of the motor;
On-delay compensation voltage estimation means for inputting a positive / negative sign of the three-phase armature current and outputting a three-phase on-delay compensation voltage;
An electric motor drive control device comprising: addition means for outputting a new AC three-phase voltage command obtained by adding the three-phase on-delay compensation voltage to the AC three-phase voltage command to the PWM inverter. The on-delay compensation voltage estimation means inputs the positive / negative sign of the three-phase armature current and sets the absolute value of the difference between the input voltage and the output voltage of the PWM inverter generated by providing an on-delay time. 2. The drive control apparatus for an electric motor according to claim 1, wherein the three-phase on-delay compensation voltage is added with a positive / negative sign of a phase armature current. A position sensor for detecting the rotor position of the electric motor; a differentiating means for differentiating the rotor position to output the rotor speed of the electric motor; and a subtracting means for subtracting a speed command by the rotor speed to obtain a speed deviation. Control compensation means for inputting the speed deviation, the rotor speed, the d-axis estimated current and the q-axis estimated current and outputting a d-axis voltage command and a q-axis voltage command; and the d-axis voltage command and the q-axis Current estimation means for inputting a voltage command and outputting the d-axis estimated current and the q-axis estimated current; and the d-axis voltage command, the q-axis voltage command, and the rotor position are input, and an AC three-phase voltage command In a current sensorless motor drive control method comprising: coordinate conversion means for outputting a PWM inverter to the PWM inverter; and a PWM inverter for receiving the three-phase voltage command and outputting a three-phase voltage for driving the motor.
The sign of the three-phase armature current of the motor is detected by a current direction sensor,
The three-phase electric machine is added to the absolute value of the difference between the input voltage and the output voltage of the PWM inverter generated by inputting the positive / negative sign of the three-phase armature current to the on-delay compensation voltage estimation means and providing an on-delay time. The three-phase on-delay compensation voltage with the sign of the child current added,
A drive control method for an electric motor, wherein a new AC three-phase voltage command obtained by adding the three-phase on-delay compensation voltage to the AC three-phase voltage command is output to the PWM inverter by an adding means.

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