JP2018198479A - Control device of synchronous motor - Google Patents

Abstract

To provide a control device which makes the torque control of high accuracy possible to realize while increasing the maximum output of the synchronous motor.SOLUTION: The control device is for controlling the synchronous motor 80 by a semiconductor power converter 70. Of the control device with a current command computing unit 18 that calculates the current commands from the torque command values of the motor 80, the current command computing unit 18 includes a magnetic flux upper limit value computing unit that calculates the magnetic flux upper limit value from the torque command values, a magnetic flux lower limit value computing unit that calculates the magnetic flux lower limit value from the torque command values, a scaling converter that calculates the scaling magnetic flux command values which have scaled the magnetic flux command values of the motor 80 in accordance with the magnetic flux upper limit values and the magnetic flux lower limit values, and a current command generation part that calculates and outputs the current command values in accordance with the function that takes the torque command values and scaled flux command value as input.SELECTED DRAWING: Figure 1

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 referred to as PMSM) or a synchronous reluctance motor (hereinafter referred to as SynRM) and realizing highly accurate torque control.

Conventionally, a technology for improving the efficiency of a synchronous motor and realizing highly accurate torque control has been developed.
For example, in the PMSM control device described in Patent Document 1, when the terminal voltage of the 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. Is higher, the magnetic flux command value is controlled so that the terminal voltage becomes equal to or lower than the limit value. Then, the load angle command value is calculated by the load angle controller 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 electric current of the electric motor according to the current command value, it is possible to improve efficiency and perform highly accurate torque control.

JP 2009-124811 A (FIGS. 1-5, etc.)

In the current command value calculation method described in Patent Document 1, in principle, the load angle needs to be a torque increasing function.
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 at which the torque / voltage is maximized. This operating point is almost the operating point at which the torque / magnetic flux is maximized. equal. However, since the load angle is not a torque increasing function at the operating point at which the torque / magnetic flux is maximized, the current command value cannot be calculated by the technique described in Patent Document 1, and as a result, the motor is operated up to the maximum output. There is a problem that can not be.

  Accordingly, an object of the present invention is to provide a control apparatus for a synchronous motor that can increase the maximum output of the synchronous motor and improve the efficiency, thereby realizing highly accurate torque control.

In order to solve the above problem, the invention described in claim 1
A control device for controlling a synchronous motor by a semiconductor power converter, comprising a current command calculator for calculating a current command value from a torque command value of the synchronous motor,
The current command calculator is
Magnetic flux upper limit value calculating means for calculating a magnetic flux upper limit value from the torque command value;
Magnetic flux lower limit value calculating means for calculating a magnetic flux lower limit value from the torque command value;
Normalization conversion means for calculating a standardized magnetic flux command value by standardizing the magnetic flux command value of the synchronous motor with the magnetic flux upper limit value and the magnetic flux lower limit value;
Means for calculating and outputting the current command value by a function having the torque command value and the standardized magnetic flux command value as inputs.
Thereby, it is possible to stably operate up to the maximum output of the synchronous motor and to control the torque with high accuracy.

According to a second aspect of the present invention, there is provided the synchronous motor control device according to the first aspect, wherein the magnetic flux upper limit calculating means is configured such 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.
Thereby, a calculation error can be reduced and torque control accuracy can be further improved.

According to a third aspect of the present invention, in the synchronous motor control device according to the first or second aspect, the magnetic flux lower limit value calculating means is configured such that the torque is equal to the torque command value and the torque / magnetic flux is maximized. Is calculated as the lower limit value of the magnetic flux.
Thereby, a calculation error can be reduced and torque control accuracy can be further improved.

According to a fourth aspect of the present invention, in the synchronous motor control device according to the first or second aspect, the magnetic flux lower limit value calculating means is configured such that when the current of the synchronous motor exceeds a current limit value, the torque is increased. The magnetic flux is calculated as the magnetic flux lower limit value, which is equal to the torque command value and the current of the synchronous motor is equal to the current limit value.
Thereby, it is possible to reduce the calculation error and further improve the torque control accuracy.

According to a fifth aspect of the present invention, in the synchronous motor control device according to any one of the first to fourth aspects, a torque limit value calculating means for calculating a torque limit value from the magnetic flux command value, and the torque limit Means for limiting the torque command value within a range of values.
Thereby, a torque can be restrict | limited appropriately according to magnetic flux command value.

According to a sixth aspect of the present invention, in the synchronous motor control device according to the fifth aspect, the torque limit value calculating means is configured such that the magnetic flux of the synchronous motor is equal to the magnetic flux command value and the torque / magnetic flux is maximized. The torque at the time of performing is calculated as the torque limit value.
Thereby, a torque can be restrict | limited to below the maximum torque of a synchronous motor.

According to a seventh aspect of the present invention, in the synchronous motor control device according to the fifth aspect, the torque limit value calculating means is configured to control the synchronous motor when the current of the synchronous motor is equal to or greater than a current limit value. 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.
Thereby, the current of the synchronous motor can be controlled to be equal to or less than the current limit value.

The invention described in claim 8 is the synchronous motor control device according to any one of claims 1 to 7, further comprising magnetic flux command value calculation means for calculating the magnetic flux command value from the torque command value, The magnetic flux command value calculation means calculates the magnetic flux when the torque of the synchronous motor is equal to the torque command value and maximizes the torque / current as the magnetic flux command value.
Thereby, the torque / current can be controlled to the maximum.

According to a ninth aspect of the present invention, in the synchronous motor control device according to any one of the first to eighth aspects, the magnetic flux command value is controlled so that a terminal voltage of the synchronous motor is equal to or lower than a voltage limit value. It has the means to do.
Thereby, the terminal voltage of a synchronous motor can be controlled below a 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 a control device concerning an embodiment of the present invention. FIG. 2 is a block diagram of a current command calculator in FIG. 1. It is a figure which shows the input-output characteristic of the normalization converter in FIG. It is a table showing the relation between the current torque command value of the command generating unit and the standardized flux command value Ψ _{a (Table)} ^* in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As is well known, the synchronous motor can realize high-performance torque control and speed control by performing control on the d and q axes constituting orthogonal rotation coordinates synchronized with the rotor.
In the case of PMSM, the N-pole direction of the rotor magnetic pole is defined as the d-axis, and the 90 ° advance direction from the d-axis is defined as the q-axis. In the case of SynRM, the direction in which the inductance is maximized is defined as the d-axis, and the direction advanced by 90 ° from 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 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 a speed detection value ω _r and a 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 a deviation between the speed command value ω _r ^* and the speed detection value ω _r, and the speed regulator 17 operates so as to make the deviation zero, and calculates the torque command value τ ^* . Based on the torque command value τ ^* , the speed detection value ω _r , the voltage limit value V _alim , and the voltage command value amplitude V _a ^* , the current command calculator 18 determines that the terminal voltage of the electric motor 80 is less than the voltage limit value V _alim. To calculate the d and q axis current command values i _d ^* and i _q ^* that maximize the efficiency of the electric motor 80 and control the torque to the torque command value τ ^* .

The voltage amplitude calculator 21 calculates the voltage command value amplitude V _a ^* from the vector sum of the d and q axis voltage command values v _d ^* and v _q ^* . The voltage limit value calculator 22 calculates the voltage limit value V _align from the DC voltage detection value E _dc obtained by the DC voltage detection circuit 12.

On the other hand, the u-phase current detector 11 u and the w-phase current detector 11 w detect the phase currents i _u and i _w flowing through the electric motor 80, respectively. The coordinate converter 14 uses these position current detection values i _u and i _w and the remaining v-phase current calculation values i _v obtained by the calculation as the two-phase quantities d and q using the position detection value θ _r. Coordinates are converted to detected shaft current values i _d and i _q .

The subtractor 19a obtains a deviation between the d-axis current command value i _d ^* and the d-axis current detection value i _d, and the d-axis current regulator 20a operates so as to make the deviation zero, and the d-axis voltage command The value v _d ^* is calculated. The subtractor 19b obtains a 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, The voltage command value v _q ^* is calculated.
The coordinate converter 15 converts the d and q axis voltage command values v _d ^* and v _q ^* into the three phase voltage command values v _u ^* , v _v ^* , and 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 ^* .
With the control described above, the speed, torque, and the like of the electric motor 80 can be controlled as instructed.

Next, 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 a magnetic flux command value Ψ _aMTPA from the torque command value τ ^* . The magnetic flux command value Ψ _aMTPA is a 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 _aMTPA by an arithmetic expression, it is calculated using a polygonal line approximation function.

The magnetic flux limit value calculator 122 calculates the magnetic flux limit value ψ _alim by Equation 1.

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 is output as the magnetic flux command value Ψ _a0 ^* .

Further, the subtractor 124 obtains a deviation between the voltage limit value V _alim and the voltage command value amplitude V _a ^* . 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, lower limit is limited to zero.

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

The magnetic flux command value Ψ _a ^* is input to the torque limit value calculator 131 to calculate the torque limit value τ _lim .
The torque limit value τ _lim is a 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 is equal to or greater than the current limit value, the torque is the same 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 an arithmetic expression, the torque limit value τ _lim is calculated using a polygonal line approximation function.

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

The standardization converter 141 is based on the input / output characteristics shown in FIG. 3, and a standardized magnetic flux command value Ψ _{a (Table)} corresponding 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 described later. ₎ ^* Is calculated and output to the current command generator 144.

The 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 respectively calculated. Here, the magnetic flux upper limit value Ψ _amax is a magnetic flux when the torque is equal to the torque command value τ ^** and the torque / current is maximized. The magnetic flux lower limit Ψ _amin is a 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, it is the magnetic flux 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, it is calculated 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 ψa _(Table) ^* , and the magnetic flux is the standardized magnetic flux command value. The d and q axis current command values i _d ^* and i _q ^* are controlled so as to be controlled to Ψ _{a (Table)} ^* . Since it is difficult to perform this calculation using an arithmetic expression, the torque command value τ ^** and the standardized magnetic flux command value ψa _(Table) ^* are input, and the d and q-axis current command values i _d ^* and i _q are input. ^The d and q axis current command values i _d ^* and i _q ^* are calculated by linearly interpolating a table that outputs ^* .

FIG. 4 shows an example of a table of torque command values and standardized magnetic flux command values 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 magnetic flux lower limit value Ψ _amin . As a result, the number of tables can be reduced, errors due to linear interpolation can be reduced, and linear interpolation calculation can be simplified.
In addition, since the speed is high when the flux-weakening control is performed, a small magnetic flux control error tends to be a large voltage control error. Therefore, as shown in FIG. 4, in a region where the magnetic flux and the torque are small, a large number of tables are provided to reduce the magnetic flux control error caused by linear interpolation.

  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 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 controller 20b q-axis current controller 21 Voltage amplitude calculator 22 Voltage limit value calculator 121 Magnetic flux command calculator 122 Magnetic flux limit value calculator 123 Output limiter 124 Subtractor 125 Magnetic flux regulator 126 Output limiter 127 Multiplier 131 Torque limit value calculator 132 Output limiter 141 Standardization converter 142 Magnetic flux upper limit value calculator 143 Magnetic flux lower limit value calculator 144 Current command generator

Claims (9)

A control device for controlling a synchronous motor by a semiconductor power converter, comprising a current command calculator for calculating a current command value from a torque command value of the synchronous motor,
The current command calculator is
Magnetic flux upper limit value calculating means for calculating a magnetic flux upper limit value from the torque command value;
Magnetic flux lower limit value calculating means for calculating a magnetic flux lower limit value from the torque command value;
Normalization conversion means for calculating a standardized magnetic flux command value by standardizing the magnetic flux command value of the synchronous motor with the magnetic flux upper limit value and the magnetic flux lower limit value;
Means for calculating and outputting the current command value by a function having the torque command value and the normalized magnetic flux command value as inputs;
A control apparatus for a synchronous motor, comprising: In the synchronous motor control device according to claim 1,
The control apparatus for a synchronous motor, wherein the magnetic flux upper limit calculating means calculates a magnetic flux when torque is equal to a torque command value and when torque / current is maximized as the magnetic flux upper limit value. In the synchronous motor control device according to claim 1 or 2,
The control apparatus for a synchronous motor, wherein the magnetic flux lower limit calculating means calculates a magnetic flux when torque is equal to a torque command value and when torque / magnetic flux is maximized as the magnetic flux lower limit. In the synchronous motor control device according to claim 1 or 2,
When the current of the synchronous motor is greater than or equal to the current limit value, the magnetic flux lower limit value calculating means calculates 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, wherein the control device calculates the lower limit of magnetic flux. In the synchronous motor control device according to any one of claims 1 to 4,
Torque limit value calculating means for calculating a torque limit value from the magnetic flux command value;
Means for limiting the torque command value within a range of the torque limit value;
A control apparatus for a synchronous motor, comprising: In the synchronous motor control device according to claim 5,
The torque limit value calculating means calculates a torque when the magnetic flux of the synchronous motor is equal to a magnetic flux command value and maximizes the torque / magnetic flux as the torque limit value. . In the synchronous motor control device according to claim 5,
When the current of the synchronous motor is equal to or greater than the current limit value, the torque limit value calculating means is configured such that the magnetic flux of the synchronous motor is equal to a magnetic flux command value and the current of the synchronous motor is equal to the current limit value. A control device for a synchronous motor, wherein the torque is calculated as the torque limit value. In the synchronous motor control device according to any one of claims 1 to 7,
Magnetic flux command value calculating means for calculating the magnetic flux command value from the torque command value,
The magnetic flux command value calculation means calculates the magnetic flux when the torque of the synchronous motor is equal to the torque command value and maximizes the torque / current as the magnetic flux command value. apparatus. In the control apparatus of the synchronous motor described in any one of Claims 1-8,
A control apparatus for a synchronous motor, comprising means for controlling the magnetic flux command value so that a terminal voltage of the synchronous motor is equal to or lower than a voltage limit value.

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