JP6726390B2 - Controller for permanent magnet type synchronous motor - Google Patents

Description

The present invention relates to a controller for a permanent magnet type synchronous motor that does not have a magnetic pole position detector, and more specifically, it reduces shock when switching between various control methods according to the speed range of the motor to smoothly accelerate and decelerate 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 has been put into practical use, which operates without using a magnetic pole position detector for detecting the magnetic pole position of the rotor.
The sensorless vector control realizes torque control and speed control 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, its detailed description is omitted here.

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

Here, for example, in Patent Document 1, there is disclosed a permanent magnet type synchronous motor which is configured to prevent a sudden change in voltage or current when switching control methods between current pull-in control and sensorless vector control to reduce shock. A controller is disclosed. Particularly, in claim 6 of Patent Document 1, paragraphs [0083] to [0093] of the specification, FIG. 6 and the like, when decelerating and stopping an electric motor during operation, shock is transferred from sensorless vector control to current drawing control. It describes the technology to switch between 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 and the d-axis is set so that the generated torque of the electric motor does not change before and after switching from sensorless vector control to current drawing control. The initial value of the current command value is calculated by Expression 24 using the initial value of the q-axis current command value obtained by Expression 23 and the current command value amplitude.
However, since the formula 23 is only an approximate formula, 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 electric motor when switching to the current drawing control. was there.

Therefore, a problem to be solved by the present invention is to permanently calculate the initial value of the current command value at the time of switching from the sensorless vector control to the current pull-in control, so that the control method can be switched without a shock. It is to provide a control device for a synchronous motor.

In order to solve the above-mentioned problems, the invention according to claim 1 is a control device for operating a permanent magnet type synchronous motor having no magnetic pole position detector by a power converter,
Capturing the current and terminal voltage of the motor as a vector,
A first operation mode for controlling an angular velocity of a current command value of the electric motor to a speed command value;
A second operation mode in which the speed of the electric motor is controlled to a speed command value using an estimated magnetic pole position value and an estimated speed value of the rotor calculated from the electric current and the terminal voltage of the electric motor,
When switching from the second operation mode to the first operation mode,
Means for calculating an angular difference between the current command value and the magnetic pole position of the rotor from the torque command value of the electric motor and the amplitude of the current command value;
Means for obtaining an electrical angle correction value from the angle difference,
Means for initializing the angle of the current command value using the electrical angle correction value;
Means for initializing a terminal voltage command value of the electric motor so that the terminal voltage of the electric motor does not suddenly change using the electrical angle correction value;
A 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 the angular velocity compensation value obtained from the deviation between the speed command value and the estimated speed value;
Equipped with
Means for calculating the angle difference between the current command value and the magnetic pole position,
A means for calculating a section of the angle difference in which torque is an increasing function of the angle difference from the amplitude of the current command value, and a torque of the electric motor matches the torque command value from the section of the angle difference. And means for calculating the angle difference .
According to the present invention, it is possible to reduce the shock at the time of switching from the sensorless vector control which is the second operation mode to the current drawing control which is the first operation mode, as compared with the prior art, and to make the permanent magnet type synchronous motor smooth. with luck a rolling Friendly ability can be simplified calculation at the time of control switching as described above.

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

It is a block diagram showing composition of an embodiment of the present invention. It is a figure which shows the definition of (gamma), (delta) axis, and (d) and (q) axis. It is a vector diagram which shows the principle of the switching process from sensorless vector control to current drawing control. It is a figure which shows the operating principle of the angular velocity compensator in FIG. It is a figure which shows the angle difference (delta) _i of the d-axis and a current vector in current drawing control, and the relationship with torque (tau). It is a vector diagram for explaining the calculation principle of the upper limit value δ _imax of the angle difference δ _i . It is a vector diagram for explaining the calculation principle of the lower limit value δ _imin of the angle difference δ _i .

Embodiments of the present invention will be described below 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 extended electromotive voltage to current drawing control without a shock. 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 the axis in the direction of the magnetic pole of the rotor, the q-axis is the axis in the direction orthogonal to the d-axis, and θ _err is the 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 velocity 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 sides of the changeover switches 21a and 21b are set to "S ₁ ". The first current command calculation unit 41 controls the γ, δ axis current command values i _γ ^* , i _δ ^* as in Expression 1.
[Equation 1]
i _γ ^* =I _apull ^*
i _δ ^* =0
here,
I _apull ^* >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 calculates the phase current detection values i _u and i _w detected by the u-phase current detector 11 u and the w-phase current detector 11 w, respectively, based on the angle θ ₁ of the γ and δ axes. The coordinates are converted into the detected current values i _γ and i _δ . This angle θ ₁ corresponds to the estimated position value of the rotor.

The subtracters 19a and 19b respectively calculate 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. Then, the current controller 20 calculates the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^* so as to make the above deviations zero.
These voltage command values v _γ ^* , v _δ ^* are converted by the voltage coordinate converter 15 into phase voltage command values v _u ^* , v _v ^* , v _w ^* based on the angle θ ₁ of the γ and δ axes. It

The voltage of the three-phase AC power supply 50 is converted into a DC voltage by the rectifier circuit 60 and supplied to the 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. Drive signals (gate signals) for controlling the phase voltage command values v _u ^* , v _v ^* , v _w ^* .
The power converter 70 controls a semiconductor switching element such as an internal IGBT based on the gate signal to change the terminal voltage of the permanent magnet synchronous motor (PMSM) 80 to the phase voltage command values v _u ^* , v _v ^* , Control to v _w ^* .

By the series of controls described above, a current vector whose amplitude is I _apull ^* and whose angular velocity is equal to the speed command value ω ^* is generated, and the rotor of the electric motor 80 is drawn into the current vector to change the rotor speed ω _r to the speed command value ω Can be controlled to ^* .

Next, the operation during sensorless vector control will be described. In the following, a description will be given focusing on the parts different from the current drawing control, and overlapping parts will be omitted.
The subtractor 16 calculates the deviation between the speed command value ω ^* and the estimated speed value ω _rest, and the speed controller 17 calculates the torque command value τ ^* so that the deviation becomes zero.

The second current command calculation unit 18 calculates the d and q axis current command values i _d ^* , i _q ^* based on the torque command value τ ^* under the condition that the torque/current is maximized.
By setting the input sides of the changeover switches 21a and 21b to "S ₂ ", the d and q axis current command values i _d ^* and i _q ^* are set as the 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 regulator 20, the current coordinate converter 14, and the voltage coordinate converter 15 are the same as those in the current pull-in control. The phase voltage command values v _u ^* , v _v ^* , v _w ^* are controlled so that the detected axial current values i _γ , i _δ match the command values i _γ ^* , i _δ ^* , respectively.

Further, the extended electromotive voltage calculator 31 uses the γ, δ-axis voltage command values v _γ ^* , v _δ ^* , the γ, δ-axis current detection values i _γ , i _δ , and the angular velocity ω ₁ to perform expansion according to Equation 2. Calculate the induced voltage.

In addition, in the calculation of Expression 2, instead of the γ and δ axis voltage command values v _γ ^* and v _δ ^* , the phase voltage or line voltage of the electric motor 80 is measured using a voltage detection circuit (not shown), and these It is also possible to use the γ-axis voltage v _γ and the δ-axis voltage v _δ calculated from the measured value and the angle (position estimated value) θ ₁ .

The angle calculator 32 calculates the angle δ _eexest of the extended electromotive voltage _according to Expression 3.

Since the angle δ _eexest of the extended electromotive voltage becomes equal to the position estimation error θ _err , the position estimation error calculation value θ _errest is _set to Expression 4.
[Equation 4]
θ _errest = δ _eexest

The speed estimator 33 is configured by a PI adjuster that receives the position estimation error calculation value θ _errest, and calculates the speed estimation value ω _rest by Expression 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 velocity 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 extended electromotive voltage calculator 31, the angle calculator 32, the speed estimator 33, and the electrical angle calculator 24 described above, the position estimation error θ _err , which is the angular difference between the γ and δ axes and the d and q axes, is zero. The speed and magnetic pole position of the rotor can be accurately calculated to accurately control the torque and speed of the electric motor 80.

Next, the principle of the switching process from the sensorless vector control to the 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, but 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 γ. Control calculation is performed by defining it as an axis.

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

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

Here, the electrical angle correction value δ _comp is calculated by the mathematical expression 6 from the above-mentioned angle difference δ _i .
[Equation 6]
δ _comp =−δ _i

Using this electrical angle correction value δ _comp , the angle θ ₁ which is the output of the electrical angle calculator 24 is initialized by the mathematical expression 7.
[Equation 7]
θ _1(n) =θ _1(n−1) −δ _comp +ω ₁ T _s
Here, T _s : sampling period In the formula 7, the subscript “n” indicates a sampling point, “n” is the current value (value after switching), and “n−1” is the previous value (before switching). Value).

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

The γ and δ axis current command values i _γf ^* , i _δf ^* and the γ and δ axis voltage command values v _γ ^* , v _δ ^* are set so that the current and the terminal voltage of the electric motor 80 do not change suddenly by the mathematical expressions 8 and 9. Can be initialized.

The angular velocity compensator 123 calculates the angular velocity compensation value ω _1comp from the start of the 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 1. _1comp is added to calculate the angular velocity ω ₁ of the γ and δ axes.
FIG. 4 is a diagram showing the operating principle of the angular velocity compensator 123. The initial value of the angular velocity compensation value ω _1comp is the deviation (ω ₁ −) between the angular velocity ω ₁ (equal to the estimated velocity value) of the γ and δ axes calculated by the subtractor 122 in FIG. 1 immediately before switching and the velocity command value ω ^*. ω ^* ), and the angular velocity compensation value ω _1comp is reduced to zero at a predetermined change rate.

Next, the contents of calculation by the current command initial value calculator 121 will be described in detail.
When operating by current drawing control, there is a relationship of Expression 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 _aPULL ^*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 the solution of the equation in which the torque τ is replaced with the torque command value τ ^* . Since the mathematical expression 10 is a non-linear equation, the angular difference δ _i may be obtained by numerical calculation such as the Newton-Raphson method or the bisection method.

As an example, a method of 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 angular difference δ _i and the torque τ shown in Expression 10. In FIG. 5, the solution of the angle difference δ _{i where} the torque τ is the torque command value τ ^* is δ _i (τ ^* ).

When the solution is obtained using the dichotomy, it is necessary to set the interval of the solution. Therefore, the lower limit value and the upper limit value of the angle difference δ _i are set to δ _imin and δ _imax , respectively. The 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 of 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 current amplitude 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 set as the current vector (2) in FIG. 6.
Here, there is a relationship of Expression 11 between the amplitude I _a of the current and the d, q-axis currents i _d , i _q .
[Equation 11]
I _a ² = _id ² +i _q ²
From Expression 11, the current vector (2) is controlled on the circular locus I _a =I _aPULL ^* .

On the other hand, there is a relationship of Expression 12 between the torque τ of the electric 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
From Expression 12, the current vector in which the torque τ is equal to the torque command value τ ^* is the parabolic locus τ=τ ^* . From the condition that the torque τ becomes larger than the torque command value τ ^* , the operating point of the current vector (2) needs to be above the parabola of τ=τ ^* .

Furthermore, the d and q axis currents i _d and i _q that maximize the torque/current have the relationship of Expression 13.

From Expression 13, the locus of the current vector that maximizes the torque/current is the parabolic locus “torque/current maximum condition” that passes through the origin in FIG. 6. Due to the condition that the torque τ is 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, the current vector when the torque τ is controlled to the torque command value τ ^* under the torque/current maximum condition is set as the 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 the torque/current maximum condition, the amplitude of the current vector (1) becomes 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 where the current amplitude is equal to the current command value amplitude I _aPULL ^* and the 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 Expression 14 is calculated from the torque command value τ ^* using a table.

The angle difference upper limit value δ _imax is calculated by Expression 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 .
From these, 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 Expression 12, in the case of an electric motor having a d-axis inductance L _d smaller than the q-axis inductance L _q , such as an embedded magnet permanent magnet synchronous motor (IPMSM), the torque τ becomes q-axis when the d-axis current i _d increases. It does not become an increasing function of the current i _q . Since the torque τ is an increasing function of the q-axis current i _q , the upper limit value of the d-axis current i _d is I _dlimp , and I _dlimp can be calculated by Expression 16.

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

From the above, in the case of the current drawing control, the d-axis current i _d is likely to be larger than the upper limit value I _dlim at the time of a light load in which the current command value amplitude I _aPULL ^* is large and the angle difference δ _i is small. 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 _dlimp of the d-axis current i _d , the torque τ becomes an increasing function of the angle difference δ _i even when the angle 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 ^* is _greater than or equal to the upper limit value I _dlimp of the d-axis current i _d , the current vector that sets the torque τ to zero has a current command value amplitude I _aPULL ^* And the d-axis current is a current vector (3) equal to its upper limit value I _dlimp . The d and q-axis currents of this current vector (3) are given by Equation 18.

The lower limit value δ _imin of the angle difference is calculated by Expression 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, from the relational expression between the angle difference δ _i and the torque τ shown in Formula 10, and the section [δ _imin , δ _imax ] of the angle difference δ _i , the angle difference for controlling the torque τ to the torque command value τ ^*. 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 converter 16, 19a, 19b: subtractor 17: speed controller 18 : Current command calculator 20: Current controllers 21a, 21b, 23: Changeover switches 22a, 22b: Low-pass filter 24: Electric angle calculator 31: Extended induced voltage calculator 32: Angle calculator 33: Speed estimator 41: Current Command calculator 50: Three-phase AC power supply 60: Rectifier circuit 70: Current converter 80: Permanent magnet type synchronous motor 121: Current command initial value calculator 122: Subtractor 123: Angular velocity compensator 124: Adder

Claims (1)

In a control device for operating a permanent magnet type synchronous motor having no magnetic pole position detector by a power converter,
Capturing the current and terminal voltage of the motor as a vector,
A first operation mode for controlling an angular velocity of a current command value of the electric motor to a speed command value;
A second operation mode in which the speed of the electric motor is controlled to a speed command value using an estimated magnetic pole position value and an estimated speed value of the rotor calculated from the electric current and the terminal voltage of the electric motor,
When switching from the second operation mode to the first operation mode,
Means for calculating an angular difference between the current command value and the magnetic pole position of the rotor from the torque command value of the electric motor and the amplitude of the current command value;
Means for obtaining an electrical angle correction value from the angle difference,
Means for initializing the angle of the current command value using the electrical angle correction value;
Means for initializing a terminal voltage command value of the electric motor so that the terminal voltage of the electric motor does not change suddenly using the electrical angle correction value;
A 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 the angular velocity compensation value obtained from the deviation between the speed command value and the estimated speed value;
Equipped with
Means for calculating the angle difference between the current command value and the magnetic pole position,
Means for calculating a section of the angular difference, where torque is an increasing function of the angular difference, from the amplitude of the current command value;
Means for calculating the angular difference so that the torque of the electric motor matches the torque command value from the angular difference section;
Controller for a permanent magnet synchronous motor and having a.

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