JP2018007473A - Control device for permanent magnet type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device capable of reducing a shock in the case of switching a sensorless vector control to current pull-in control, and making a permanent magnet type synchronous motor smoothly operable.SOLUTION: The control device comprises: an angle arithmetic unit 32 for, in the case of switching a second operation mode (sensorless vector control) for controlling a motor speed to a speed command value by using a magnetic pole position estimation value and a speed estimation value calculated from currents and a terminal voltage of a motor 80 to a first operation mode (current pull-in control) for controlling an angular speed of a current command value of the motor 80 to a speed command value, calculating an angular difference between the current command value and a magnetic pole position from amplitudes of a torque command value and the current command value; a current command initialization arithmetic unit 121 and an electric angle arithmetic unit 24 or the like for initializing an angle of the current command value and a terminal voltage command value by using an electric angle correction value calculated from the angular difference; and an angular speed compensator 124 and an adder 124 or the like for correcting the angular speed of the current command value by using an angular speed compensation value calculated from a deviation between the speed command value and the speed estimation value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a permanent magnet type synchronous motor that does not have a magnetic pole position detector. More specifically, the present invention relates to a smooth acceleration / deceleration of a motor by reducing a shock when switching various control methods according to the speed range of the motor. The present invention relates to a control device for driving.

In order to reduce the cost of the control device for the permanent magnet type synchronous motor, so-called sensorless vector control, which is operated without using a magnetic pole position detector for detecting the magnetic pole position of the rotor, has been put into practical use.
In sensorless vector control, torque control and speed control are realized by calculating the magnetic pole position and speed of the rotor from information on the terminal voltage and current of the electric motor, and performing current control based on these. Since a specific method of sensorless vector control is well known, detailed description thereof is omitted here.

  However, since sensorless vector control has a problem in stability in a low speed region such as at the time of starting, the rotation of the motor is controlled by controlling the angular velocity of the current to the speed command value while keeping the current amplitude of the motor constant. A technique for driving a child by drawing it into an electric current may be applied. Hereinafter, such an operation method is referred to as “current drawing control”.

  Here, for example, Patent Document 1 discloses a permanent magnet type synchronous motor that prevents a sudden change in voltage and current when switching control methods between current pull-in control and sensorless vector control to reduce shock. A control device is disclosed. In particular, claim 6 of Patent Document 1 and paragraphs [0083] to [0093] of the specification, FIG. 6 and the like show a shock from sensorless vector control to current drawing control when the operating motor is decelerated and stopped. It describes the technology to switch with less.

Japanese Patent No. 5277724 (Claim 6, paragraphs [0083] to [0093], FIG. 6 etc.)

In Patent Document 1 described above, the initial value of the q-axis current command value at the time of switching is calculated by Equation 23 so that the generated torque of the motor does not change before and after switching from sensorless vector control to current pull-in control, and d-axis The initial value of the current command value is calculated by Equation 24 using the initial value of the q-axis current command value obtained by Equation 23 and the current command value amplitude.
However, since Formula 23 is only an approximate expression, the current command value does not become an appropriate value due to the approximation error, and as a result, a shock occurs in the torque generated by the motor when switching to current pull-in control. was there.

  Therefore, the problem to be solved by the present invention is that a permanent magnet type that enables switching of the control method in a shockless manner by appropriately calculating the initial value of the current command value at the time of switching from sensorless vector control to current pull-in control. It is to provide a control device for a synchronous motor.

In order to solve the above-mentioned problem, an invention according to claim 1 is a control device for operating a permanent magnet synchronous motor having no magnetic pole position detector by a power converter.
Taking the current and terminal voltage of the motor as a vector,
A first operation mode for controlling the angular velocity of the current command value of the electric motor to a speed command value;
A second operation mode for controlling the speed of the motor to a speed command value using a rotor magnetic pole position estimated value and a speed estimated value calculated from the current and terminal voltage of the motor;
When switching from the second operation mode to the first operation mode,
Means for calculating an angle difference between the current command value and the magnetic pole position of the rotor from the torque command value of the motor and the amplitude of the current command value;
Means for obtaining an electrical angle correction value from the angle difference;
Means for initializing an angle of the current command value using the electrical angle correction value;
Means for initializing a terminal voltage command value of the motor so that the terminal voltage of the motor does not change suddenly using the electrical angle correction value;
Means for correcting the angular velocity of the current command value so that the angular velocity of the current command value does not change suddenly using an angular velocity compensation value obtained from a deviation between the velocity command value and the estimated speed value. is there.
According to the present invention, the shock at the time of switching from the sensorless vector control that is the second operation mode to the current pull-in control that is the first operation mode can be reduced more than before, and the permanent magnet type synchronous motor can be made smoother. It is possible to drive.

According to a second aspect of the present invention, in the control device for the permanent magnet type synchronous motor according to the first aspect, the means for calculating the angular difference between the current command value and the magnetic pole position is based on the amplitude of the current command value. Means for calculating the angle difference section in which torque is an increasing function of the angle difference, and means for calculating the angle difference from the angle difference section so that the torque of the motor matches the torque command value. And.
ADVANTAGE OF THE INVENTION According to this invention, the calculation at the time of switching from sensorless vector control to electric current drawing control can be simplified.

  According to the present invention, it is possible to reduce a shock when switching the control method of a permanent magnet type synchronous motor having no magnetic pole position detector from sensorless vector control to current pull-in control, and to realize, for example, smooth operation during deceleration. it can.

It is a block diagram which shows the structure of embodiment of this invention. It is a figure which shows the definition of (gamma), (delta) axis | shaft and d, q axis. It is a vector diagram which shows the principle of the switching process from sensorless vector control to electric current drawing control. It is a figure which shows the principle of operation of the angular velocity compensator in FIG. It is a figure which shows the relationship between angle difference (delta) _i of d axis | shaft and electric current vector, and torque (tau) in electric current drawing control. FIG. 6 is a vector diagram for explaining the calculation principle of an upper limit value δ _imax of the angle difference δ _i . It is a vector diagram for _{demonstrating} the calculation principle of lower limit value (delta) _imin of angle difference (delta) _i .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a control device according to this embodiment together with a main circuit. The control method of a permanent magnet type synchronous motor is changed from sensorless vector control using an extended induced voltage to current drawing control in a shockless manner. It is for switching.

The calculation in the control device is performed by an orthogonal rotation coordinate system composed of γ and δ axes rotating at an angular velocity ω _{1 as} shown in FIG. In FIG. 2, the d axis is an axis in the magnetic pole direction of the rotor, the q axis is an axis perpendicular to the d axis, and θ _err is a position estimation error.

First, the operation at the time of current drawing control of this embodiment will be described together with the configuration of the control device.
Returning to FIG. 1, the input side of the changeover switch 23 is set to “S ₁ ”, and the angular velocity ω ₁ of the γ and δ axes is controlled to the speed command value ω ^* output from the adder 124. Electrical angle calculator 24, gamma integrates the angular velocity omega _1, calculates the angle theta ₁ of the δ-axis.

On the other hand, the input side of the changeover switches 21a and 21b is set to “S ₁ ”. The first current command calculation unit 41 controls the γ and δ-axis current command values i _γ ^* and i _δ ^* as shown in Equation 1.
[Equation 1]
i _γ ^* = I _pull ^*
i _δ ^* = 0
here,
_Iapple ^* > 0

Low pass filter 22a, 22b is, gamma, [delta] -axis current value i _{γ ^*,} i _δ ^* of low-frequency component i _.gamma.f ^*, calculates i _{delta] f} ^*, respectively.
The current coordinate converter 14 converts the phase current detection values i _u and i _w detected by the u-phase current detector 11u and the w-phase current detector 11w, respectively, into the γ and δ axes based on the angle θ ₁ of the γ and δ axes. Coordinates are converted to current detection values i _γ and i _δ . This angle θ ₁ corresponds to the estimated position value of the rotor.

By the subtractors 19a and 19b, the deviation between the γ-axis current command value i _γf ^* and the γ-axis current detection value i _γ and the deviation between the δ-axis current command value i _δf ^* and the δ-axis current detection value i _δ are respectively determined. The current regulator 20 calculates the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^* so that the deviations are zero.
These voltage command values v _γ ^* and v _δ ^* are converted into phase voltage command values v _u ^* , v _v ^* and v _w ^* by the voltage coordinate converter 15 based on the angle θ ₁ of the γ and δ axes. The

The voltage of the three-phase AC power supply 50 is converted into a DC voltage by the rectifier circuit 60 and supplied to a power converter 70 such as an inverter. The PWM circuit 13 outputs the output voltage of the power converter 70 from the phase voltage command values v _u ^* , v _v ^* , v _w ^* and the DC input voltage E _dc of the power converter 70 detected by the input voltage detection circuit 12. _Is driven to a phase voltage command value v _u ^* , v _v ^* , v _w ^* , a drive signal (gate signal) is generated.
The power converter 70 controls a semiconductor switching element such as an internal IGBT based on the gate signal, thereby changing the terminal voltage of the permanent magnet type synchronous motor (PMSM) 80 to the phase voltage command values v _u ^* , v _v ^* , Control to v _w ^* .

By a series of control described above, the amplitude _I apull ^_*, the angular velocity is equal to the current vector is generated in the speed command value omega ^*, the speed command value rotor speed omega _r rotor of the electric motor 80 is drawn to the current vector omega ^* Can be controlled.

Next, the operation at the time of sensorless vector control will be described. Below, it demonstrates centering on a different part from current drawing-in control, and it abbreviate | omits about the overlapping part.
The subtractor 16 calculates the deviation between the speed command value ω ^* and the estimated speed value ω _rest, and the speed regulator 17 calculates the torque command value τ ^* so that this deviation becomes zero.

Based on the torque command value τ ^* , the second current command calculation unit 18 calculates the d and q-axis current command values i _d ^* and i _q ^* under the condition that the torque / current is maximized.
By setting the input side of the changeover switches 21a and 21b to “S ₂ ”, d and q axis current command values i _d ^* and i _q ^* are set as γ and δ axis current command values i _γ ^* and i _δ ^*. To do.

The operations of the low-pass filters 22a and 22b, the subtractors 19a and 19b, the current adjuster 20, the current coordinate converter 14 and the voltage coordinate converter 15 are the same as those in the case of the current pull-in control. The phase voltage command values v _u ^* , v _v ^* , and v _w ^* are controlled so that the detected shaft current values i _γ and i _δ coincide with the command values i _γ ^* and i _δ ^* , respectively.

Further, the expansion induced voltage calculator 31 is expanded by Equation 2 using γ, δ-axis voltage command values v _γ ^* , v _δ ^* , γ, δ-axis current detection values i _γ , i _δ , and angular velocity ω _1. Calculate the induced voltage.

In the calculation of Equation 2, the phase voltage or line voltage of the motor 80 is measured using a voltage detection circuit (not shown) instead of the γ and δ-axis voltage command values v _γ ^* and v _δ ^* , Alternatively, the measurement may be performed using the γ-axis voltage v _γ and the δ-axis voltage v _δ calculated from the measured value and the angle (position estimation value) θ ₁ .

The angle calculator 32 calculates the angle δ _exeest of the expansion induced voltage using Equation 3.

Since the angle δ _exeest of the extended induced voltage is equal to the position estimation error θ _err , the position estimation error calculation value θ _errest is _expressed by Equation 4.
[Equation 4]
θ _errest = δ _exeest

The speed estimator 33 is configured by a PI controller that receives the position estimation error calculation value θ _errest as an input, and calculates the speed estimation value ω _rest using Equation 5.

By setting the input side of the changeover switch 23 to “S ₂ ”, the angular velocity ω ₁ of the γ and δ axes is controlled to the estimated speed value ω _rest .
Electrical angle calculator 24, like the case of the current pull-in control, calculates the angle theta ₁ which integrates the angular velocity omega ₁ corresponds to the position estimate of the rotor.

By the operations of the above-described extended induced voltage calculator 31, angle calculator 32, speed estimator 33, and electrical angle calculator 24, the position estimation error θ _err , which is the angle difference between the γ and δ axes and the d and q axes, is reduced to zero. The torque and speed of the motor 80 can be accurately controlled by accurately calculating the rotor speed and magnetic pole position.

Next, the principle of switching processing from sensorless vector control to current drawing control will be described based on the vector diagram of FIG.
In the sensorless vector control, the current command vector i ^* is controlled so that the torque / current is maximized. In the current pull-in control, generally, the current command value is controlled to be constant, and the direction of the current command vector i ^* is set to γ. Define the axis and perform control calculation.

Therefore, when switching from sensorless vector control to current draw control, the current command value is calculated so that the torque does not change before and after switching, and the angle difference δ _i between the d-axis (magnetic pole position) and the current command vector i ^* is calculated. Then, using this angle difference δ _i , the angle θ ₁ of the γ and δ axes is initialized. At the same time, the voltage command vector v ^* and the current command vector _if ^* that are the outputs of the low-pass filters 22a and 22b are initialized so as to be continuous before and after switching.

Next, calculation processing when switching from sensorless vector control to current drawing control will be described.
Immediately after switching from sensorless vector control to current pull-in control, the current command initial value calculator 121 in FIG. 1 calculates the angle difference δ _i for controlling the torque of the motor 80 to the torque command value τ ^* during sensorless vector control. Calculate. The details of the calculation by the current command initial value calculator 121 will be described in detail later.

Here, the electrical angle correction value δ _comp is calculated from the angle difference δ _i described above using Equation 6.
[Equation 6]
δ _comp = −δ _i

Using this electrical angle correction value δ _comp , the angle θ ₁ that is the output of the electrical angle calculator 24 is initialized by Equation 7.
[Equation 7]
θ _{1 (n)} = θ _{1 (n−1)} −δ _comp + ω ₁ T _s
Here, T _s : Sampling period In Equation 7, the subscript “n” indicates the sampling point, “n” indicates the current value (value after switching), and “n−1” indicates the previous value (before switching). Value).

As the angle θ ₁ of the γ and δ axes is corrected by δ _comp by Equation 7, γ and δ axis current command values i _γf ^* and i _δf ^* which are outputs of the low-pass filters 22a and 22b, and a current regulator Γ and δ-axis voltage command values v _γ ^* and v _δ ^* , which are 20 outputs, are initialized by Equations 8 and 9, respectively.

From Equations 8 and 9, γ and δ-axis current command values i _γf ^* and i _δf ^* and γ and δ-axis voltage command values v _γ ^* and v _δ ^* are set so that the current of the motor 80 and the terminal voltage do not change suddenly. It can be initialized.

The angular velocity compensator 123 calculates the angular velocity compensation value ω _1comp from the start of current drawing control so that the angular velocity ω ₁ of the γ and δ axes does not change suddenly at the time of switching, and the adder 124 calculates the velocity command value ω ^* and the angular velocity compensation value ω. γ by adding the _1Comp, calculates an angular velocity omega ₁ of the δ-axis.
FIG. 4 is a diagram illustrating the operating principle of the angular velocity compensator 123. The initial value of the angular velocity compensation value omega _1Comp is, gamma was computed by a subtracter 122 of FIG. 1 just before switching, [delta] axes of the angular velocity omega _{1 (equal} to the speed estimation value) and the speed command value omega ^* and the deviation of (omega ₁ - ω ^* ), and the angular velocity compensation value ω _1comp is reduced to zero at a predetermined change rate.

Next, the calculation contents by the current command initial value calculator 121 will be described in detail.
When operating by current pull-in control, there is a relationship of Equation 10 between the torque τ of the electric motor 80 and the angle difference δ _i .
[Equation 10]
τ = I _aPULL ^* Ψ _m sin δ _i + I a _PULL ^{* 2} (L _d −L _q ) sin δ _i cos δ _i
However, Ψ _m : permanent magnet magnetic flux angle difference δ _i is obtained from a solution of an equation in which the torque τ is replaced with a torque command value τ ^* . Since Equation 10 is a nonlinear equation, the angle difference δ _i may be obtained by numerical calculation such as Newton-Raphson method or bisection method.

As an example, a method for obtaining the angle difference δ _i by the bisection method will be described. The bisection method has a feature that the operation can be simplified as compared with other calculation methods such as the Newton-Raphson method.
FIG. 5 shows the relationship between the angle difference δ _i shown in Formula 10 and the torque τ. In FIG. 5, let δ _i (τ ^* ) be the solution of the angle difference δ _{i where} the torque τ is the torque command value τ ^* .

When finding a solution using the bisection method, it is necessary to set a solution interval. For this reason, the lower limit value and the upper limit value of the angle difference δ _i are set to δ _imin and δ _imax , respectively. Current pull-in control can be performed stably when the torque τ is an increasing function of the angle difference δ _i . Therefore, the lower limit value [delta] _imin and an upper limit [delta] _imax of angular difference [delta] _i is the angular difference δi interval [δ _imin, δ _imax] torque τ in decide to be an increasing function.

Next, a method for calculating the upper limit value δ _imax of the angle difference δ _i will be described. FIG. 6 is a vector diagram for explaining the calculation principle of the upper limit value δ _imax of the angle difference δ _i .
The amplitude of the current is controlled to the current command value amplitude I _aPULL ^*, and the current vector when the angle difference δ _i is the angle difference upper limit value δ _imax is defined as a current vector (2) in FIG.
Here, there is a relationship of Formula 11 between the current amplitude I _a and the d and q axis currents i _d and i _q .
[Equation 11]
I _a ² = _id ² + i _q ²
From Equation 11, the current vector (2) is controlled on _a circular locus I _a = I _aPULL ^* .

On the other hand, there is a relationship of Formula 12 between the torque τ of the motor and the d and q axis currents i _d and i _q .
[Equation 12]
_{τ = Ψ m i q + (} L d -L q) i d i q
According to Equation 12, the current vector in which the torque τ is equal to the torque command value τ ^* is a parabolic locus τ = τ ^* . From the condition for the torque τ to become larger than the torque command value τ ^* , the operating point of the current vector (2) needs to be above the parabola of τ = τ ^* .

Further, d and q-axis currents i _d and i _q that maximize the torque / current are in the relationship of Equation 13.

From Equation 13, the locus of the current vector that maximizes the torque / current is the parabolic locus “torque / current maximum condition” passing through the origin in FIG. From the condition for the torque τ to become an increasing function of the angle difference δ _i , the current vector (2) needs to be on the left side of the parabola of the torque / current maximum condition.

The angle difference upper limit value δ _imax is calculated by the procedure described below so as to satisfy the above conditions.
First, a current vector when the torque τ is controlled to the torque command value τ ^* under the maximum torque / current condition is defined as a current vector (1). This current vector (1) reaches the intersection of the parabola of τ = τ ^{* and} the parabola of the torque / current maximum condition. Since the current vector (1) is a torque / current maximum condition, the amplitude of the current vector (1) is smaller than the current command value amplitude I _aPULL ^* .

数式１４におけるＩ_{ｄＭＴＰＡ}は、トルク指令値τ^＊からテーブルを用いて演算する。 Next, the current vector (2) is selected as an operating point whose current amplitude is equal to the current command value amplitude I _aPULL ^* and whose d-axis current is equal to the d-axis current i _dMTPA of the current vector (1). Specifically, the calculation is performed using Equation 14.

I _dMTPA in Equation 14 is calculated from the torque command value τ ^* using a table.

The angle difference upper limit value δ _imax is calculated by Equation 15 from the angle difference between the d-axis and the current vector (2).

Since the operating point of the current vector (2) is above the parabola of τ = τ ^* , the torque τ is larger than the torque command value τ ^* . Further, since it is on the left side of the parabola of the torque / current maximum condition, the torque τ is an increasing function of the angle difference δ _i .
For these reasons, the angle difference upper limit value δ _imax calculated from the angle difference between the d-axis and the current vector (2) satisfies the necessary condition.

特に、ｄ軸電流ｉ_ｄがＩ_{ｄｌｉｍｐ}である場合、トルクτはｑ軸電流ｉ_ｑによらず、零になる。 Next, a method of calculating the lower limit value δ _imin of the angle difference δ _i will be described. FIG. 7 is a vector diagram for explaining the calculation principle of the lower limit value δ _imin of the angle difference δ _i .
From Equation 12, as in the embedded magnet permanent magnet synchronous motor (IPMSM), d-axis inductance L _d is for small motors than the q-axis inductance L _q, d-axis current i _d is increased the torque τ is q-axis It does not become an increasing function of the current _iq . If the upper limit value of the d-axis current i _d for the torque τ is an increasing function of the q-axis current i _q is I _dlim , I _dlim can be calculated by Equation 16.

In particular, when the d-axis current i _d is I _dlimp , the torque τ is zero regardless of the q-axis current i _q .

From the above, in the case of the current pull-in control, the current command value amplitude _{I aPULL} ^* is large, d-axis current _{i d} at the angle difference [delta] _i is less light load tends to increase than the upper limit value _{I Dlim.} Therefore, the lower limit value δ _imin of the angle difference is designed in consideration of this.

First, when the current command value amplitude I _aPULL ^* is smaller than the upper limit value I _dlim of the d-axis current i _d , the torque τ becomes an increasing function of the angular difference δ _i even when the angular difference δ _i is small. Therefore, as shown in Expression 17, the lower limit value δ _imin of the angle difference is set to 0.
[Equation 17]
δ _imin = 0

On the other hand, when the current command value amplitude _{I aPULL} ^* greater than or equal to the upper limit value _{I Dlimp} the d-axis current _{i d,} the current vector with zero torque tau, as shown in FIG. 7, the amplitude current command value amplitude _{I aPULL} ^* And the d-axis current becomes a current vector (3) equal to the upper limit value I _dlimp . The d and q axis currents of this current vector (3) are expressed by Equation 18.

The lower limit value δ _imin of the angle difference is calculated by Equation 19 from the angle difference between the d-axis and the current vector (3).

By the calculation described above, the section [δ _imin , δ _imax ] of the angle difference δ _{i in which} the torque τ becomes an increasing function and the torque command value τ ^* exists can be calculated. As a result, the angle difference for controlling the torque τ to the torque command value τ ^* from the relational expression between the angle difference δ _i and the torque τ shown in Equation 10 and the section [δ _imin , δ _imax ] of the angle difference δ _i. It is possible to calculate δ _{i (τ *)} by the bisection method.

11u: u-phase current detection circuit 11w: w-phase current detection circuit 12: input voltage detection circuit 13: PWM circuit 14: current coordinate converter 15: voltage coordinate converters 16, 19a, 19b: subtractor 17: speed regulator 18 : Current command calculator 20: Current regulators 21a, 21b, 23: Changeover switches 22a, 22b: Low-pass filter 24: Electrical angle calculator 31: Extended induced voltage calculator 32: Angle calculator 33: Speed estimator 41: Current Command calculation unit 50: Three-phase AC power supply 60: Rectifier circuit 70: Current converter 80: Permanent magnet synchronous motor 121: Current command initial value calculator 122: Subtractor 123: Angular velocity compensator 124: Adder

Claims (2)

In a control device for operating a permanent magnet type synchronous motor without a magnetic pole position detector by a power converter,
Taking the current and terminal voltage of the motor as a vector,
A first operation mode for controlling the angular velocity of the current command value of the electric motor to a speed command value;
A second operation mode for controlling the speed of the motor to a speed command value using a rotor magnetic pole position estimated value and a speed estimated value calculated from the current and terminal voltage of the motor;
When switching from the second operation mode to the first operation mode,
Means for calculating an angle difference between the current command value and the magnetic pole position of the rotor from the torque command value of the motor and the amplitude of the current command value;
Means for obtaining an electrical angle correction value from the angle difference;
Means for initializing an angle of the current command value using the electrical angle correction value;
Means for initializing a terminal voltage command value of the motor so that the terminal voltage of the motor does not change suddenly using the electrical angle correction value;
Means for correcting the angular velocity of the current command value so that the angular velocity of the current command value does not change suddenly using an angular velocity compensation value obtained from a deviation between the speed command value and the estimated speed value;
A control device for a permanent magnet type synchronous motor. In the control device for the permanent magnet type synchronous motor according to claim 1,
Means for calculating the angle difference between the current command value and the magnetic pole position,
Means for calculating a section of the angle difference from which the torque is an increasing function of the angle difference from the amplitude of the current command value;
Means for calculating the angle difference so that the torque of the motor matches the torque command value from the angle difference section;
A control device for a permanent magnet type synchronous motor.

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