JP5092572B2 - Control device for permanent magnet type synchronous motor - Google Patents

Description

  The present invention relates to a control device for a permanent magnet type synchronous motor that does not have a position detector for detecting the magnetic pole position of a rotor, and more particularly to a technique for improving efficiency during low-speed operation.

In order to reduce the cost of the control device for the permanent magnet type synchronous motor, so-called sensorless control that operates without using a position detector that detects the magnetic pole position of the rotor has been put into practical use. In the sensorless 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 armature current of the motor, and performing current control based on these. An example of sensorless control is described in Non-Patent Document 1, for example.
However, the sensorless control described in Non-Patent Document 1 has a problem in terms of stability because it causes a voltage drop of the armature resistance, an output voltage error of the power converter, and the like during low-speed operation.

For this reason, Patent Document 3 discloses a drive system that drives a permanent magnet type synchronous motor with high accuracy without depending on the value of the armature resistance.
The drive system according to Patent Document 3 includes a reactive power actual value calculated from a voltage command value and a current detection value for a synchronous motor, and a reactive power estimation value calculated from an output angular frequency command value and a current detection value of an inverter. By adjusting the output angular frequency of the inverter to make the deviation zero, the axial error of the synchronous motor is reduced, and the synchronous motor is driven sensorlessly with high accuracy without being affected by the temperature change of the armature resistance. is there.
However, in this drive system, the reactive power is always zero at zero speed, so that information on the magnetic pole position cannot be detected from the reactive power, and there is a problem in stability at extremely low speed.

Therefore, as described in Patent Document 1, a technique for performing synchronous pull-in operation by generating a rotating magnetic field by making the frequency of the armature current coincide with the frequency command value while keeping the amplitude of the armature current constant during low-speed operation. May apply. Such an operation method is called “current draw control”.
By the way, the current drawing control is capable of stable operation up to zero speed in principle, but it is difficult to control the magnitude of the armature current according to the magnitude of the load. Therefore, considering the stability, it is necessary to determine the magnitude of the armature current based on the maximum torque specified by the application.At light loads, the armature current increases and the efficiency decreases. There is a problem that the capacity of the inverter to be driven increases.

Against this background, in recent years, a technique has been developed that controls the magnitude of the armature current during current drawing control according to the load.
For example, Non-Patent Document 2 calculates reactive power and active power from the terminal voltage and armature current of a permanent magnet synchronous motor, and sets the magnitude of the armature current so that the ratio between the two becomes a target value. A control method for optimal control is described.

  Further, in Patent Document 2, focusing on the fact that the angular difference between the position of the N pole (d-axis) of the rotor permanent magnet and the armature current vector becomes an increasing function of the load, the terminal voltage and the armature current are A control device is described in which the angle difference is calculated from a voltage equation model of an input permanent magnet synchronous motor, and an armature current command value is calculated as an increasing function of the angle difference.

Koji Tanaka and Ichiro Miki, “Position Sensorless Control of Embedded Magnet Synchronous Motor Using Extended Inductive Voltage”, IEEJ Transactions D, Vol.125, No.9, p.833-p.838 (2005) Shinji Shinnaka, “Current-ratio vector control method for sensorless start-up and drive of permanent magnet synchronous motors—Feedback control of effective reactive current based on Mir method”, IEEJ Transactions D, Vol.126, No .3, p.225-p.236 (2006) JP 2001-190093 (paragraph [0007], FIG. 7 etc.) JP 2001-136775 A (paragraphs [0038] to [0063] etc.) Japanese Patent Laying-Open No. 2006-197712 (paragraphs [0010] to [0020], FIG. 1 and the like)

  By the way, the calculation of the active power in Non-Patent Document 2 and the angle difference in Patent Document 2 requires that the value of the armature resistance of the permanent magnet synchronous motor be accurately determined. However, since the armature resistance changes depending on the temperature of the armature winding, in the conventional techniques described in Non-Patent Document 2 and Patent Document 2, the influence of the voltage drop due to the armature resistance on the motor terminal voltage becomes large. There is a risk that the control performance will decrease at low speeds.

  Accordingly, an object of the present invention is to provide a control device that can operate a permanent magnet type synchronous motor stably and efficiently even at low speeds.

In order to solve the above-mentioned problem, the control device for a permanent magnet type synchronous motor according to claim 1 makes the magnitude of the armature current of the permanent magnet type synchronous motor coincide with the current command value, and sets the frequency of the armature current. In a control device for controlling the terminal voltage of the motor by a power converter so as to match the frequency command value,
Current command calculation means for generating the current command value,
Reactive power calculating means for calculating reactive power from the terminal voltage and armature current of the motor, reactive power command calculating means for calculating reactive power command value from the armature current of the motor and frequency command value, and the reactive power Means for generating the current command value using a signal obtained by amplifying the deviation between the power command value and the reactive power calculation value.

According to a second aspect of the present invention, there is provided a control device for the permanent magnet type synchronous motor, wherein the configuration of the current command calculating means is different from that of the first aspect.
That is, the current command calculation means of the present invention includes a reactive voltage calculation means for calculating a reactive voltage that is a voltage component orthogonal to the armature current from the terminal voltage and the armature current of the motor, and the armature current of the motor. Reactive voltage command calculation means for calculating a reactive voltage command value from a frequency command value; and means for generating the current command value using a signal obtained by amplifying a deviation between the reactive voltage command value and the reactive voltage calculation value. It is provided.

According to a third aspect of the present invention, there is provided a control device for the permanent magnet type synchronous motor, wherein the configuration of the current command calculation means is different from the first and second aspects.
That is, the current command calculation means of the present invention is a reactive magnetic flux calculation means for calculating a reactive magnetic flux that is a magnetic flux parallel to the armature current from the terminal voltage, armature current, and frequency command value of the motor,
A reactive magnetic flux command calculating means for calculating a reactive magnetic flux command value from the armature current of the motor;
Means for generating the current command value using a signal obtained by amplifying the deviation between the reactive magnetic flux command value and the reactive magnetic flux calculation value.

According to the present invention, it is possible to calculate a current command value without being influenced by armature resistance in principle using a reactive power deviation, a reactive voltage deviation, or a reactive magnetic flux deviation, and to increase a current at a light load. Can be prevented to prevent the efficiency from decreasing.
In addition, the control performance is hardly deteriorated even at a low speed, and the permanent magnet type synchronous motor can be driven stably.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is a block diagram showing a control device according to this embodiment together with a main circuit. In the main circuit of FIG. 1, 50 is a three-phase AC power source, 60 is a rectifier circuit that converts a three-phase AC voltage into a DC voltage, and 70 is an electric power such as an inverter that converts the DC voltage into an AC voltage of a predetermined magnitude and frequency. A converter 80 is a permanent magnet synchronous motor to which the output voltage of the power converter 70 is supplied.
The electric motor 80 does not include a magnetic pole position detector.

First, a method for controlling the power converter 70 so that the magnitude of the armature current of the motor 80 matches the current command value and the frequency of the armature current matches the frequency command value will be described.
First, the control calculation is performed on orthogonal coordinates (γ-δ axes) rotating at an angular frequency ω ₁ . FIG. 5 is a diagram showing definitions of the γ-δ axis and the dq axis, and θ _err is an angle difference between the γ-δ axis and the dq axis. An axis parallel to the magnetic flux axis by the permanent magnet rotor of the electric motor 80 is d-axis, and an axis orthogonal to the d-axis is q-axis. Incidentally, d-q axis or rotor shall be rotated at the angular frequency omega _r.

The current command calculator 18 calculates the frequency command value ω ^* (= ω ₁ ), the γ-axis and δ-axis current detection values i _γ and i _δ , and the γ-axis and δ-axis voltage command values v _γ ^* and v _δ ^*. , Γ-axis, δ-axis current command values i _γ ^* , i _δ ^* are calculated. Details of the calculation by the current command calculator 18 will be described later.

The electrical angle calculator 12 calculates the electrical angle command value θ ₁ by integrating the frequency command value ω ₁ .
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 on the input side of the electric motor 80 are obtained by the current coordinate converter 14 using the electrical angle command value θ _1. Coordinates are converted to γ-axis and δ-axis current detection values i _γ and i _δ , respectively.

The deviation between the γ-axis current command value i _γ ^* output from the current command calculator 18 and the detected γ-axis current value i _γ is calculated by the subtractor 19a, and this deviation is amplified by the γ-axis current regulator 20a to be γ The shaft voltage command value _vγ ^* is calculated. On the other hand, the deviation between the δ-axis current command value i _δ ^* and the detected δ-axis current value i _δ is calculated by the subtractor 19b, and this deviation is amplified by the δ-axis current regulator 20b to be amplified by the δ-axis voltage command value v _δ ^*. Is calculated.
These γ-axis and δ-axis 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 using the electrical angle command value θ ₁ ^. Is converted to

The PWM circuit 13 generates a gate signal for controlling the output voltage of the power converter 70 to the phase voltage command values v _u ^* , v _v ^* , v _w ^* .
The power converter 70 turns on and off the internal semiconductor switching element based on the gate signal, and controls the terminal voltage of the electric motor 80 to the phase voltage command values v _u ^* , v _v ^* , v _w ^* .

Next, the detailed configuration and operation of the current command calculator 18 will be described.
First, when the δ-axis current i _δ is controlled to zero, the reactive power Q is expressed by Equation 1. That is, the reactive power Q is a function of the angle difference θ _err and the γ-axis current i _γ .

In the case of a permanent magnet type synchronous motor having a surface magnet structure, the γ-axis current can be minimized by controlling the angle difference θ _err to 90 [deg]. On the other hand, in the case of a permanent magnet type synchronous motor having an embedded magnet structure, the γ-axis current can be minimized by controlling the angle difference θ _err to a predetermined operating point of 90 to 135 [deg].

For this reason, if the reactive power Q is controlled to a value obtained by substituting the value of the angle difference θ _err that minimizes the γ-axis current into Equation 1, according to the structure of the permanent magnet synchronous motor, the γ-axis current Can be minimized and the influence of the armature resistance can be reduced. However, in practice, in consideration of stability, it is preferable to control the γ-axis current so that the reactive power Q is slightly larger than the value under the aforementioned minimum current condition.
Note that Formula 1 does not include the value of the armature resistance. That is, according to the present embodiment, there is no influence of the armature resistance, and there is no possibility that the performance is deteriorated even at a low speed.

FIG. 2 is a block diagram showing a first embodiment of the current command calculator 18 in FIG. In FIG. 2, the current command calculator is indicated by reference numeral 181.
In FIG. 2, the reactive power command calculator 101 calculates the reactive power command value Q ^{* according} to Equation 2.

This equation 2 corresponds to the equation 1 when i _δ is zero, and the reactive power command calculation coefficients K _Q1 and K _Q2 in the equation 2 are K _Q1 = ψ _m cos θ _err , K _Q2 = L _q + (L _d −L _q ) cos ² θ _err .
On the other hand, the reactive power calculator 102 calculates the reactive power Q using Equation 3.

The deviation between the reactive power command value Q ^* and the reactive power calculation value Q is calculated by the subtractor 103, and this deviation is amplified by the integral controller 104. Further, the original current command value I _a0 ^* and the output of the integral controller 104 are added by the adder 105, and the result is given to the subtracter 19a in FIG. 1 as the γ-axis current command value i _γ ^* . The δ-axis current command value i _δ ^* is controlled to zero.

As a result, the current command calculator 181 calculates the γ-axis current command value i _γ ^* so that the reactive power Q matches the reactive power command value Q ^* calculated from the armature current of the motor 80 and the frequency command value. Therefore, in principle, control based on reactive power that is not affected by armature resistance is executed.

FIG. 3 is a block diagram showing a second embodiment of the current command calculator. In FIG. 3, the current command calculator is indicated by reference numeral 182.
When the δ-axis current is controlled to be zero, the reactive voltage v _Q defined as a component orthogonal to the armature current among the terminal voltage components is expressed by Equation 4.

Relationship of reactive voltage v _Q shown in Equation 4, is proportional to the relation of the reactive power Q as shown in Equation 1. Therefore, as in the first embodiment, if the reactive voltage v _Q is controlled to a value obtained by substituting the value of the angle difference θ _err at which the γ-axis current is minimized into Equation 4, the minimum γ-axis current is obtained. Can be realized. Again, in view of the stability, it is preferable to control the γ-axis current to be slightly larger than the value when the current minimum condition that disables voltage v _Q is as described above.

In FIG. 3, the reactive voltage command calculator 201 calculates the reactive voltage command value v _Q ^* using Equation 5.

The equation 5 corresponds to the equation 4 when i _δ is zero, and the reactive voltage command calculation coefficients K _vQ1 and K _vQ2 in the equation 5 are K _vQ1 = ψ _m cos θ _err , K _vQ2 = L _q + (L _d −L _q ) cos ² θ _err .
On the other hand, reactive voltage calculator 202 calculates the equation 6 invalid voltage _{v Q.}

The deviation between the reactive voltage command value v _Q ^* and the reactive voltage calculation value v _Q is calculated by the subtractor 203, and this deviation is amplified by the integral controller 204. Further, the current command value I _a0 ^* and the output of the integral controller 204 are added by the adder 205, and the result is given to the subtracter 19a in FIG. 1 as the γ-axis current command value i _γ ^* . The δ-axis current command value i _δ ^* is controlled to zero.

As a result, in the current command calculator 182 of FIG. 1, the γ-axis current command value i so that the reactive voltage v _Q matches the reactive voltage command value v _Q ^* calculated from the armature current of the motor 80 and the frequency command value. _γ ^* is calculated, and control that is not influenced by the armature resistance in principle is executed as in the first embodiment.

FIG. 4 is a block diagram showing a third embodiment of the current command calculator. In FIG. 4, the current command calculator is indicated by reference numeral 183.
When the δ-axis current is controlled to be zero, the reactive magnetic flux ψ _Q defined as a component parallel to the armature current among the components of the interlinkage magnetic flux is expressed by Equation 7.

Relationship of invalid magnetic flux [psi _Q shown in Equation 7, is proportional to the relation of the reactive power Q as shown in Equation 1. Therefore, as in the first embodiment, if the reactive magnetic flux ψ _Q is controlled to a value obtained by substituting the value of the angle difference θ _err that minimizes the γ-axis current into Equation 7, the minimum of the γ-axis current is reduced. Can be realized. Again, in view of the stability, it is preferable to control the γ-axis current to be slightly larger than the value when the current minimum condition that disables flux [psi _Q is as described above.

In FIG. 4, a reactive magnetic flux command calculator 301 calculates a reactive magnetic flux command value ψ _Q ^* using Equation 8.

The equation 8 corresponds to the equation 7 when i _δ is zero, and the reactive magnetic flux command calculation coefficients K _ψQ1 and K _ψQ2 in the equation 8 are K _ψQ1 = ψ _{m cosθ err} , K _ψQ2 = L _q + (L _d −L _q ) cos ² θ _err .
Invalid flux calculator 302 calculates the equation (9) to disable flux [psi _Q.

The deviation between the reactive magnetic flux command value ψ _Q ^* and the reactive magnetic flux calculation value ψ _Q is calculated by the subtractor 303, and this deviation is amplified by the integral controller 304. The original current command value I _a0 ^* and the output of the integral controller 304 are added by the adder 305, and the result is given to the subtracter 19a in FIG. 1 as the γ-axis current command value i _γ ^* . The δ-axis current command value i _δ ^* is controlled to zero.

In the present embodiment, in the current command calculator 182 of FIG. 1, the γ-axis current command value i _γ ^* is set so that the reactive magnetic flux ψ _Q ^* matches the reactive magnetic flux command value ψ _Q ^* calculated from the armature current of the motor 80. As in the first and second embodiments, in principle, control that is not affected by the armature resistance is executed.

It is a block diagram which shows embodiment of this invention. It is a block diagram which shows the 1st Example of a current command calculator. It is a block diagram which shows the 2nd Example of an electric current instruction | command calculator. It is a block diagram which shows the 3rd Example of an electric current command calculating unit. It is a figure which shows the definition of dq axis | shaft and (gamma) -delta axis | shaft.

Explanation of symbols

50 three-phase AC power supply 60 rectifier circuit 70 power converter 80 permanent magnet type synchronous motor 11u u-phase current detection circuit 11w w-phase current detection circuit 12 electrical angle calculator 13 PWM circuit 14 current coordinate converter 15 voltage coordinate converter 18, 181, 182, 183 Current command calculators 19a, 19b Subtractor 20a γ-axis current regulator 20b δ-axis current regulator 101 Reactive power command calculator 102 Reactive power calculators 103, 203, 303 Subtractors 104, 204, 304 Integration Controllers 105, 205, 305 Adder 201 Reactive voltage command calculator 202 Reactive voltage calculator 301 Reactive magnetic flux command calculator 302 Reactive magnetic flux calculator

Claims (3)

In order to control the terminal voltage of the motor by the power converter so that the magnitude of the armature current of the permanent magnet type synchronous motor matches the current command value and the frequency of the armature current matches the frequency command value In the control device of
Current command calculation means for generating the current command value,
Reactive power calculation means for calculating reactive power from the terminal voltage and armature current of the motor;
Reactive power command calculation means for calculating a reactive power command value from the armature current of the motor and the frequency command value;
Means for generating the current command value using a signal obtained by amplifying a deviation between the reactive power command value and the reactive power calculation value;
A control device for a permanent magnet type synchronous motor. In order to control the terminal voltage of the motor by the power converter so that the magnitude of the armature current of the permanent magnet type synchronous motor matches the current command value and the frequency of the armature current matches the frequency command value In the control device of
Current command calculation means for generating the current command value,
Reactive voltage calculation means for calculating a reactive voltage that is a voltage component orthogonal to the armature current from the terminal voltage and the armature current of the motor;
Reactive voltage command calculation means for calculating a reactive voltage command value from the armature current of the motor and the frequency command value;
Means for generating the current command value using a signal obtained by amplifying a deviation between the reactive voltage command value and the reactive voltage calculation value;
A control device for a permanent magnet type synchronous motor. In order to control the terminal voltage of the motor by the power converter so that the magnitude of the armature current of the permanent magnet type synchronous motor matches the current command value and the frequency of the armature current matches the frequency command value In the control device of
Current command calculation means for generating the current command value,
A reactive magnetic flux calculating means for calculating a reactive magnetic flux that is a magnetic flux parallel to the armature current from the terminal voltage of the motor, the armature current, and the frequency command value;
A reactive magnetic flux command calculating means for calculating a reactive magnetic flux command value from the armature current of the motor;
Means for generating the current command value using a signal obtained by amplifying a deviation between the reactive magnetic flux command value and the reactive magnetic flux calculation value;
A control device for a permanent magnet type synchronous motor.

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