JP6848680B2 - Synchronous motor control device - Google Patents

Description

The present invention relates to a technique for increasing the maximum output of a synchronous motor such as a permanent magnet synchronous motor (hereinafter, PMSM) and a synchronous reluctance motor (hereinafter, SynRM) and realizing highly accurate torque control.

Conventionally, technologies have been developed that improve the efficiency of synchronous motors and realize highly accurate torque control.
For example, in the PMSM control device described in Patent Document 1, when the terminal voltage of the electric motor is lower than the limit value, the magnetic flux command value is controlled so that the torque / current is maximized, and the terminal voltage is lower than the limit value. If it is also high, the magnetic flux command value is controlled so that the terminal voltage is below the limit value. Then, the load angle command value is calculated by the load angle adjuster so that the torque of the electric motor becomes equal to the torque command value, and the current command value is calculated from the magnetic flux command value and the load angle command value. By controlling the current of the electric motor according to this current command value, it is possible to improve efficiency and control torque with high accuracy.

Japanese Unexamined Patent Publication No. 2009-124811 (FIGS. 1 to 5 and the like)

In the method of calculating the current command value described in Patent Document 1, in principle, the load angle needs to be an increasing function of torque.
On the other hand, when the terminal voltage of the motor is controlled to the limit value, the output is maximized at the operating point where the torque / voltage is maximized, and this operating point is almost the operating point where the torque / magnetic flux is maximized. equal. However, at the operating point where the torque / magnetic flux is maximized, the load angle is no longer a torque increasing function, so the current command value cannot be calculated by the technique described in Patent Document 1, and as a result, the motor operates to the maximum output. There is a problem that it cannot be done.

Therefore, an object of the present invention is to provide a control device for a synchronous motor that can increase the maximum output of the synchronous motor, improve the efficiency, and realize highly accurate torque control.

In order to solve the above problems, the invention according to claim 1 is
In a control device for controlling a synchronous motor by a semiconductor power converter, in a control device including a current command calculator that calculates a current command value from a torque command value of the synchronous motor.
The current command calculator
A magnetic flux upper limit value calculating means for calculating the magnetic flux upper limit value from the torque command value, and
A magnetic flux lower limit value calculating means for calculating the magnetic flux lower limit value from the torque command value, and
A standardized conversion means for calculating a standardized magnetic flux command value by standardizing the magnetic flux command value of the synchronous motor based on the magnetic flux upper limit value and the magnetic flux lower limit value.
It is characterized by including means for calculating and outputting the current command value by a function that inputs the torque command value and the standardized magnetic flux command value.
As a result, stable operation can be performed up to the maximum output of the synchronous motor, and torque can be controlled with high accuracy.

The invention according to claim 2 is the magnetic flux when the torque is equal to the torque command value and the torque / current is maximized in the control device for the synchronous motor according to claim 1. Is calculated as the upper limit value of the magnetic flux.
As a result, the calculation error can be reduced and the torque control accuracy can be further improved.

The invention according to claim 3 is the control device for the synchronous motor according to claim 1 or 2, wherein the magnetic flux lower limit value calculation means equals the torque command value and maximizes the torque / magnetic flux. It is characterized in that the magnetic flux of is calculated as the lower limit value of the magnetic flux.
As a result, the calculation error can be reduced and the torque control accuracy can be further improved.

According to the fourth aspect of the present invention, in the control device for the synchronous motor according to the first or second aspect, the magnetic flux lower limit value calculation means increases the torque when the current of the synchronous motor becomes equal to or more than the current limit value. It is characterized in that the magnetic flux when it is equal to the torque command value and the current of the synchronous motor is equal to the current limit value is calculated as the magnetic flux lower limit value.
As a result, the calculation error can be reduced and the torque control accuracy can be further improved.

The invention according to claim 5 is a torque limit value calculation means for calculating a torque limit value from the magnetic flux command value and the torque limit in the control device for the synchronous motor according to any one of claims 1 to 4. It is characterized by providing means for limiting the torque command value within the range of the value.
Thereby, the torque can be appropriately limited according to the magnetic flux command value.

The invention according to claim 6 is the control device for the synchronous motor according to claim 5, wherein the torque limit value calculation means makes the magnetic flux of the synchronous motor equal to the magnetic flux command value and maximizes the torque / magnetic flux. It is characterized in that the torque at that time is calculated as the torque limit value.
As a result, the torque can be limited to the maximum torque of the synchronous motor or less.

The invention according to claim 7 is the control device for the synchronous motor according to claim 5, wherein when the current of the synchronous motor becomes equal to or more than the current limit value, the torque limit value calculation means of the synchronous motor. It is characterized in that the torque when the magnetic flux is equal to the magnetic flux command value and the current of the synchronous motor is equal to the current limit value is calculated as the torque limit value.
As a result, the current of the synchronous motor can be controlled to be equal to or less than the current limit value.

The invention according to claim 8 comprises a magnetic flux command value calculating means for calculating the magnetic flux command value from the torque command value in the control device for the synchronous motor according to any one of claims 1 to 7. The magnetic flux command value calculating means is characterized in that the torque of the synchronous motor is equal to the torque command value and the magnetic flux when the torque / current is maximized is calculated as the magnetic flux command value.
Thereby, the torque / current can be controlled to the maximum.

The invention according to claim 9 controls the magnetic flux command value so that the terminal voltage of the synchronous motor becomes equal to or less than the voltage limit value in the control device for the synchronous motor according to any one of claims 1 to 8. It is characterized by having a means for doing so.
As a result, the terminal voltage of the synchronous motor can be controlled to be equal to or lower than the voltage limit value.

According to the present invention, it is possible to increase the maximum output of the synchronous motor and realize highly accurate torque control.

It is a block diagram of the control device which concerns on embodiment of this invention. It is a block diagram of the current command arithmetic unit in FIG. It is a figure which shows the input / output characteristic of the standardized converter in FIG. It is a table which shows the relationship between the torque command value of the current command generation part in FIG. 2 and the standardized magnetic flux command value Ψ _{a (Table)} ^*.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As is well known, a synchronous motor can realize high-performance torque control and speed control by controlling on the d and q axes constituting orthogonal rotating coordinates synchronized with the rotor.
In the case of PMSM, the north pole direction of the magnetic poles of the rotor is defined as the d-axis, and the 90 ° advancing direction from this d-axis is defined as the q-axis. Further, in the case of SynRM, the direction in which the inductance becomes maximum is defined as the d-axis, and the direction 90 ° ahead of the d-axis is defined as the q-axis.

FIG. 1 is a block diagram showing a control device for a synchronous motor 80 such as a PMSM according to this embodiment.
First, speed control, current control, and voltage control of the synchronous motor 80 will be described with reference to FIG.

_{The position / speed detection circuit 91 obtains the speed detection value ω r} and the position detection value θ _r from the output signal of the position / speed sensor 90 attached to the synchronous motor 80. The detected values ω _r and θ _r may be calculated from the current and terminal voltage of the electric motor 80 without using the position / speed sensor 90 and the position / speed detection circuit 91.

The subtractor 16 obtains the deviation between the speed command value ω _r ^* and the speed detection value ω _r, and the speed controller 17 operates so as to make the deviation zero and calculates the ^{torque command value τ *.} Current command calculator 18, the torque command value tau ^*, the speed detection value omega _r, voltage limit value _{V alim,} based on voltage command value amplitude _V ^{a *,} the terminal voltage of the motor 80 is a voltage limit value _{V alim} following conditions Calculates the d, q-axis current command values _id ^* and i _q ^* that maximize the efficiency of the motor 80 ^{and control the torque to the torque command value τ *.}

The voltage amplitude calculator 21, d, q-axis voltage command value _v ^d _{*, v} from the vector sum of ^{q *,} calculates the voltage command value amplitude _V ^{a *.} Voltage limit value calculation unit 22, the DC voltage detection value _{E dc} obtained by the DC voltage detection circuit 12, calculates a voltage limit value _{V alim.}

On the other hand, the u-phase current detectors 11u and the w-phase current detectors 11w detect the phase currents i _u and i _w flowing through the electric motor 80, respectively. Coordinate converter 14, these phase current detection value i _u, i _w, and the remaining v-phase current calculation value i _v obtained by the calculation, the two-phase quantity with the detected position value theta _r d, q Coordinates are converted to the axial current detection values _id and i _q.

The subtractor 19a obtains the deviation between the d-axis current command value _id ^* and the d-axis current detection value _id, and the d-axis current regulator 20a operates so as to make the deviation zero and the d-axis voltage command. Calculate the value v _d ^*. Further, the subtractor 19b obtains the deviation between the q-axis current command value i _q ^* and the q-axis current detection value i _q, and the q-axis current regulator 20b operates so as to make the deviation zero. Calculate the voltage command value v _q ^*.
The coordinate converter 15 converts the d, q-axis voltage command values v _d ^* , v _q ^* into the three-phase quantity phase voltage command values v _u ^* , v _v ^* , v _w ^* using the position detection value θ _r. The coordinates are converted and output to the PWM circuit 13.

The rectifier circuit 60 supplies a DC voltage obtained by rectifying the three-phase AC power supply 50 to a power converter 70 such as an inverter.
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 controls 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 ^* .
By the control described above, the speed, torque, etc. of the electric motor 80 can be controlled according to the command value.

Next, the details of the current command calculator 18 in FIG. 1 will be described with reference to FIG.
In FIG. 2, the magnetic flux command calculator 121 calculates the magnetic flux command value Ψ _aMTPA ^{from the torque command value τ *} . This magnetic flux command value Ψ _aMTPA is the magnetic flux when the torque is equal to the torque command value τ ^* and the torque / current is maximized. Since it is difficult to obtain Ψ a _MTPA by an arithmetic expression, the polygonal line approximation function is used for the calculation.

The magnetic flux limit value calculator 122 calculates the magnetic flux limit value Ψ _alim by the mathematical formula 1.

_{The upper limit of the magnetic flux command value Ψ aMTPA} output from the magnetic flux command calculator 121 is limited to the magnetic flux limit value Ψ _alim by the output limiter 123, and the magnetic flux command value Ψ _a0 ^* is output.

Further, a deviation between the voltage limit value _{V alim} and the voltage command value amplitude _V ^{a *} by the subtractor 124. Flux adjuster 125 having integrated regulator, operate to zero the deviation calculates the flux correction factor K _[psi, the flux correction factor K _[psi is an upper limit by the output limiter 126 1.0 Double, the lower limit is limited to zero.

The magnetic flux command value Ψ _a0 ^* _{output from the output limiters 123} and 126 and the magnetic flux correction coefficient K _{Ψ a} are multiplied by the multiplier 127, and the magnetic flux command value Ψ ^{a *} is calculated. As a result, the magnetic flux command value Ψ _a ^* for controlling the terminal voltage of the electric motor 80 to be equal to _{or lower than the voltage limit value of Valim} can be calculated.

The magnetic flux command value Ψ _a ^* is input to the torque limit value calculator 131, and the torque limit value τ _lim is calculated.
This torque limit value τ _lim is the torque when the magnetic flux is equal to the magnetic flux command value Ψ _a ^* and the torque / magnetic flux is maximized. However, when the current exceeds the current limit value, the torque is used when the magnetic flux is equal to the magnetic flux command value Ψ _a ^{* and the current is equal to the current limit value.}
Since it is difficult to obtain the torque limit value τ _lim by the calculation formula, the calculation is performed using the polygonal line approximation function.

The torque command value τ ^* is output as the torque command value τ ^** by limiting the upper limit value to the torque limit value τ _lim and the lower limit value to (−τ _lim ) by the output limiter 132. Thereby, the torque can be limited to the maximum torque or less of the electric motor 80 and the current can be limited to the current limit value or less according to the magnetic flux command value Ψ _a ^*.

Based on the input / output characteristics shown in FIG. 3, the standardized converter 141 has a standardized magnetic flux command value Ψ _{a (Table) according to a} magnetic flux command value Ψ ^{a *} _{including a magnetic flux upper limit value Ψ amax} and a magnetic flux lower limit value Ψ _{amin, which will be described later. )} ^* Is calculated and output to the current command generation unit 144.

Further, the above-mentioned torque command value τ ^** is input to the magnetic flux upper limit value calculator 142 and the magnetic flux lower limit value calculator 143, and the magnetic flux upper limit value Ψ _amax and the magnetic flux lower limit value Ψ _amin are calculated, respectively. Here, the magnetic flux upper limit value Ψ _amax is the magnetic flux when the torque is equal to the torque command value τ ^** and the torque / current is maximized. The lower limit of magnetic flux Ψ _amin is the magnetic flux when the torque is equal to the torque command value τ ^** and the torque / magnetic flux is maximized.
However, when the current exceeds the limit value, the magnetic flux is used when the torque is equal to the torque command value τ ^{** and the current is equal to the limit value.} Since it is difficult to obtain the magnetic flux upper limit value Ψ _amax and the magnetic flux lower limit value Ψ _amin by an arithmetic expression, the calculation is performed using a polygonal line approximation function.

The current command generation unit 144 controls the torque to the torque command value τ ^{** based on the torque command value τ **} and the standardized magnetic flux command value Ψ _{a (Table)} ^* , and sets the magnetic flux to the standardized magnetic flux command value. Calculate the d, q-axis current command values _id ^* , i _q ^* that are controlled by Ψ _{a (Table)} ^*. Since it is difficult to perform this calculation by an arithmetic expression, the torque command value τ ^** and the standardized magnetic flux command value Ψ _{a (Table)} ^* are input, and the d, q-axis current command values _id ^* , i _q. ^{By linearly interpolating the table that outputs *} , the d and q-axis current command values _id ^* and i _q ^* are calculated.

FIG. 4 shows an example of a table of the torque command value and the standardized magnetic flux command value Ψ _{a (Table)} ^{* in the current command generation unit 144.}
The magnetic flux table is prepared in the range of 0 to 1 [pu] between the normally used magnetic flux upper limit value Ψ _amax and the magnetic flux lower limit value Ψ _amin. As a result, the number of tables can be reduced, the error caused by linear interpolation can be reduced, and the linear interpolation operation can be simplified.
Further, when the weak magnetic flux control is performed, the speed is high, so that a small magnetic flux control error tends to become a large voltage control error. Therefore, as shown in FIG. 4, in the region where the magnetic flux and the torque are small, the magnetic flux control error due to the linear interpolation is reduced by providing a large number of tables.

INDUSTRIAL APPLICABILITY The present invention can be used as a control device for driving various synchronous motors such as PMSM and SynRM by a power converter such as an inverter.

50 Three-phase AC power supply 60 Rectifier circuit 70 Power converter 80 Synchronous electric motor 90 Position / speed sensor 91 Position / speed detection circuit 11u u-phase current detector 11w w-phase current detector 12 DC voltage detection circuit 13 PWM circuit 14 Coordinate converter 15 Coordinate converter 16 Subtractor 17 Speed controller 18 Current command calculator 19a, 19b Subtractor 20a d-axis current regulator 20b q-axis current regulator 21 Voltage amplitude calculator 22 Voltage limit calculator 121 Voltage limit calculator 122 Voltage limit calculator 123 Output limiter 124 Subtractor 125 Current flux regulator 126 Output limiter 127 Multiplier 131 Torque limit value calculator 132 Output limiter 141 Standardized converter 142 Voltage upper limit calculator 143 Voltage lower limit calculator 143 144 Current command generator

Claims (9)

In a control device for controlling a synchronous motor by a semiconductor power converter, in a control device including a current command calculator that calculates a current command value from a torque command value of the synchronous motor.
The current command calculator
A magnetic flux upper limit value calculating means for calculating the magnetic flux upper limit value from the torque command value, and
A magnetic flux lower limit value calculating means for calculating the magnetic flux lower limit value from the torque command value, and
A standardized conversion means for calculating a standardized magnetic flux command value by standardizing the magnetic flux command value of the synchronous motor based on the magnetic flux upper limit value and the magnetic flux lower limit value.
A means for calculating and outputting the current command value by a function that inputs the torque command value and the standardized magnetic flux command value, and
A control device for a synchronous motor, which is characterized by being equipped with. In the control device for the synchronous motor according to claim 1,
The magnetic flux upper limit value calculating means is a control device for a synchronous motor, characterized in that the torque is equal to the torque command value and the magnetic flux when the torque / current is maximized is calculated as the magnetic flux upper limit value. In the control device for the synchronous motor according to claim 1 or 2.
The magnetic flux lower limit value calculation means is a control device for a synchronous motor, characterized in that the torque is equal to the torque command value and the magnetic flux when the torque / magnetic flux is maximized is calculated as the magnetic flux lower limit value. In the control device for the synchronous motor according to claim 1 or 2.
When the current of the synchronous motor becomes equal to or more than the current limit value, the magnetic flux lower limit value calculation means obtains the magnetic flux when the torque is equal to the torque command value and the current of the synchronous motor is equal to the current limit value. A control device for a synchronous motor, which is characterized in that it is calculated as the lower limit of magnetic flux. In the control device for the synchronous motor according to any one of claims 1 to 4.
A torque limit value calculation means for calculating a torque limit value from the magnetic flux command value, and
A means for limiting the torque command value within the range of the torque limit value, and
A control device for a synchronous motor, which is characterized by being equipped with. In the control device for the synchronous motor according to claim 5.
The torque limit value calculating means is a control device for a synchronous motor, wherein the magnetic flux of the synchronous motor is equal to the magnetic flux command value, and the torque when the torque / magnetic flux is maximized is calculated as the torque limit value. .. In the control device for the synchronous motor according to claim 5.
When the current of the synchronous motor exceeds the current limit value, the torque limit value calculation means equals the magnetic flux of the synchronous motor to the magnetic flux command value and the current of the synchronous motor equals the current limit value. A control device for a synchronous motor, characterized in that the torque of is calculated as the torque limit value. In the control device for the synchronous motor according to any one of claims 1 to 7.
A magnetic flux command value calculating means for calculating the magnetic flux command value from the torque command value is provided.
The magnetic flux command value calculating means controls the synchronous motor, wherein the torque of the synchronous motor is equal to the torque command value, and the magnetic flux when the torque / current is maximized is calculated as the magnetic flux command value. apparatus. In the control device for the synchronous motor according to any one of claims 1 to 8.
A control device for a synchronous motor, which comprises means for controlling the magnetic flux command value so that the terminal voltage of the synchronous motor becomes equal to or lower than a voltage limit value.

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