JP2006014431A - Current sensorless controller and control method for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensorless controller and a control method for a motor which can perform high-performance control with good power efficiency even in case that the influence of on duty time can not be ignored such that the load is heavy and so the rotational speed is low. <P>SOLUTION: This current sensorless controller comprises an on delay compensated voltage estimating means 18 which receives the input of a d-axis estimated current and a q-axis estimated current and the position of a rotor and outputs three-phase on delay compensated voltage, and an addition means 19 which outputs a new AC three-phase voltage command where the three-phase on delay compensated voltage is added to an AC three-phase voltage command to a PWM inverter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and a control method for controlling an electric motor with high performance and high efficiency without using a current 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, motor drive systems are required to be smaller, lighter, cheaper and more reliable, so we want to reduce the number of sensors if possible. However, a position sensor is indispensable for high-performance control.
Conventionally, a control system is configured using an estimated current value without using a current sensor (see, for example, Non-Patent Document 1).
FIG. 3 is a block diagram showing a configuration of a conventional current sensorless control device for an electric motor.
In FIG. 3, 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 input voltage of the motor and the estimated current match the actual current. 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

Since the current sensorless control device for a conventional motor ignores the effect of on-delay and configures the control system, when the load is heavy and the rotation speed is low, the voltage command is the motor input voltage due to the effect of the on-delay time, Since the estimated current deviates from the actual current, the characteristics of the control system are not as designed and are 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 a current sensorless control device for an electric motor capable of performing power-efficient and high-performance control by compensating for the influence of on-delay and configuring a control system, and 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,
On-delay compensation voltage estimation means for inputting the d-axis estimation current, the q-axis estimation current, and the rotor position and outputting a three-phase on-delay compensation voltage to the addition means;
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.
According to a second aspect of the present invention, in the first aspect of the present invention, the on-delay compensation voltage estimating means is configured to generate a dq / q based on the d-axis estimated current, the q-axis estimated current, and the rotor position. Three-phase alternating current coordinate transformation is performed to calculate a three-phase estimated current, the sign of the three-phase estimated current is determined, and the difference between the input voltage and the output voltage of the PWM inverter caused by providing an on-delay time The three-phase on-delay compensation voltage is obtained by adding the positive / negative sign to the absolute value.
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 differentiating means for differentiating the rotor position and outputting a rotor speed of the electric motor, and a speed command for the rotor speed. Subtracting means for obtaining a speed deviation by subtracting at, 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 to output the d-axis estimated current and the q-axis estimated current, the d-axis voltage command, the q-axis voltage command, and the rotor Current sensorless control comprising coordinate conversion means for inputting a position and outputting an AC three-phase voltage command to a PWM inverter, and a PWM inverter for inputting the three-phase voltage command and outputting a three-phase voltage for driving the motor In the method,
The on-delay compensation voltage estimating means calculates a three-phase estimated current by performing (dq) / 3-phase AC coordinate conversion based on the d-axis estimated current, the q-axis estimated current, and the rotor position, and calculating the three-phase estimated current. The positive / negative sign of the estimated current is determined, and the positive / negative sign is added to the absolute value of the difference between the input voltage and the output voltage of the PWM inverter generated by providing the on-delay time, and the three-phase on-delay compensation voltage is obtained. 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.

  According to the present invention, since the on-delay compensation voltage is calculated using the estimated current and added to the voltage command, the voltage command closely matches the input voltage of the motor, so the estimated current matches the armature current well. Therefore, it is possible to provide a current sensorless control device and a control method for an electric motor that can 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 a current sensorless control device for an electric motor 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 . An on-delay compensation voltage estimator 18 calculates three-phase on-delay compensation voltages Δv _us , Δv _vs , Δv _ws based on the d and q axis estimated currents i _ds , i _qs and the rotor position θ _m . 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 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.
The present invention is different from Non-Patent Document 1 in that it includes an on-delay compensation voltage estimator 18 and an adder 19.

FIG. 2 is a block diagram showing the configuration of the on-delay compensation voltage estimator in FIG. In the figure, reference numeral 181 denotes a dq / 3-phase AC coordinate converter, which is a three-phase estimated current i _us , i _vs , i _ws based on the d and q axis estimated currents i _ds and i _qs and the rotor position θ _m. Calculate A current direction determiner 182 determines the positive and negative signs S _ius , S _ivs , and S _iws of the three-phase estimated current based on the three-phase estimated currents i _us , i _vs , and i _ws . Reference numeral 183 denotes an on-delay voltage constant ΔV, which is an absolute value of a difference between the input voltage and the output voltage of the PWM inverter caused by providing the on-delay time. _Reference numeral 184 denotes a multiplier, which is obtained by multiplying the on-delay voltage constant ΔV by the positive and negative signs S _ius , S _ivs , and S _iws of the three-phase estimated current as three-phase on-delay compensation voltages Δv _us , Δv _vs , Δv _ws .

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 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.
Further, according to FIG. 2, the three-phase on-delay compensation voltage is ΔV _us = Sign (i _us ) · ΔV (6)
ΔV _vs = Sign (i _vs ) · ΔV (7)
ΔV _ws = Sign (i _ws ) · ΔV (8)
It becomes.
If the estimated current matches the armature current, the equations (3) to (8)
ΔV _us = ΔV _u = V _ur1 −V _u (9)
ΔV _vs = ΔV _v = V _vr1 −V _v (10)
ΔV _ws = ΔV _w = V _wr1 −V _w (11)
It becomes.
Further, according to FIG. 1, the three-phase voltage command is V _ur = V _ur1 −ΔV _us = V _u (12)
V _vr = V _vr1 -ΔV _vs = V _v (13)
V _wr = V _wr1 −ΔV _ws = V _w (14)
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.
In this way, by adding the on-delay compensation voltage calculated based on the estimated current to the voltage command to compensate for the influence of the on-delay time, the voltage command can be matched with the voltage of the motor. The estimated current can be matched with the armature current. When stabilization compensation and non-interference compensation are performed using this estimated current, it is possible to perform high-performance and high-efficiency control in the same manner as when there is a current sensor without using a 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. Compared with the case of using the prior art (FIG. 4), when using the technique of the present invention (FIG. 5), the estimated current matches well with the armature current, the speed response follows the speed command well, and d It can be seen that the axial current is also small.

  The technique of the present invention can accurately estimate the current by compensating for the influence of on-delay, and thus can be applied to current sensorless control of a magnetic levitation system using a PWM inverter.

The block diagram of the electric current sensorless control apparatus of the electric motor which shows the Example of this invention The block diagram which shows the structure of the on-delay compensation voltage estimator in the electric current sensorless control apparatus of the electric motor of this invention The block diagram which shows the structure of the electric current sensorless control apparatus of the motor of a prior art The figure which shows the simulation result of the current sensorless control of the electric motor using a prior art The figure which shows the simulation result of the electric current sensorless control of the electric motor using the technique of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Subtractor 11 Control compensator 12 Current estimator 13, 181 dq / 3 phase AC coordinate converter 14 PWM inverter 15 Motor 16 Position sensor 17 Differentiator 18 On-delay compensation voltage estimator 19 Adder 182 Current direction determiner 183 On-delay voltage constant 184 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.
On-delay compensation voltage estimation means for inputting the d-axis estimation current, the q-axis estimation current, and the rotor position and outputting a three-phase on-delay compensation voltage to the addition means;
Adding means for outputting a new AC three-phase voltage command to the PWM inverter by adding the three-phase on-delay compensation voltage to the AC three-phase voltage command;
An electric current sensorless control device for an electric motor.   The on-delay compensation voltage estimating means calculates a three-phase estimated current by performing (dq) / 3-phase AC coordinate conversion based on the d-axis estimated current, the q-axis estimated current, and the rotor position, and calculating the three-phase estimated current. The positive / negative sign of the phase estimation current is determined and the positive / negative sign is added to 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, and the three-phase on-delay compensation voltage The current sensorless control apparatus for an electric motor according to claim 1. 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 method comprising: coordinate conversion means for outputting a PWM inverter to the PWM inverter; and a PWM inverter for outputting the three-phase voltage for driving the electric motor by receiving the three-phase voltage command.
The on-delay compensation voltage estimating means calculates a three-phase estimated current by performing (dq) / 3-phase AC coordinate conversion based on the d-axis estimated current, the q-axis estimated current, and the rotor position, and calculating the three-phase estimated current. The positive / negative sign of the estimated current is determined, and the positive / negative sign is added to the absolute value of the difference between the input voltage and the output voltage of the PWM inverter generated by providing the on-delay time, and the three-phase on-delay compensation voltage is obtained. Output to the adding means,
A current sensorless 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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