JP2009124876A - Control device of permanent magnet type synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable stable current control and high-accuracy torque control even if a terminal voltage of a permanent magnet type synchronous motor is controlled to a maximum output voltage of a power converter. <P>SOLUTION: The control device of the permanent magnet type synchronous motor comprises: an input voltage detector 12; a voltage limit value operator 22; a voltage amplitude operator 21; a current command operation part 18; and current adjusters 20a, 20b. The current command operation part 18 comprises: a q-axis current command value operator 131 which operates a q-axis current command value from a torque command value; a magnetic flux adjuster 122 which operates a magnetic flux correction value by amplifying a difference between a voltage limit value and a voltage command value; an adder 124 which operates a second magnetic flux limit value by adding a first magnetic flux limit value and the magnetic flux correction value; a d-axis current limit value operator 132 which operates a d-axis current limit value from the second magnetic flux limit value and a q-axis current command; and an output limiter 133 which limits an upper limit value of the d-axis current command value by using the d-axis current limit value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention realizes stable current control even when the terminal voltage of the permanent magnet type synchronous motor is increased to the maximum output voltage of the power converter, enabling high efficiency of the motor and high precision torque control. The present invention relates to a control device for a permanent magnet type synchronous motor.

  The permanent magnet type synchronous motor (hereinafter also referred to as PMSM) is composed of a surface magnet structure permanent magnet type synchronous motor (hereinafter also referred to as SPMSM) and an embedded magnet structure permanent magnet type synchronous motor (IPMSM) depending on the structure of the rotor. There are two main types. Among these, the IPMSM can use not only the magnet torque generated by the permanent magnet of the rotor but also the reluctance torque generated by the saliency of the rotor. It can be improved and the motor can be downsized.

By the way, PMSM realizes high-performance control by taking current, magnetic flux, and terminal voltage as vectors and performing current control on the d and q axes, which are rotating coordinate axes that rotate in synchronization with the rotor. Is possible. Here, in the definition of the d and q axes, the magnetic pole direction of the permanent magnet is the d axis, and the direction advanced 90 degrees from the d axis is the q axis. Conventionally, a method of controlling the d-axis current to zero and controlling the q-axis current in proportion to the torque command value has been often used.
However, in recent years, a technique for reducing the size and increasing the efficiency of the drive system by actively controlling the d-axis current has been put into practical use.

For example, in Non-Patent Document 1, the d-axis armature reaction when a d-axis current is passed is used to reduce the interlinkage magnetic flux (hereinafter also simply referred to as magnetic flux) of the armature winding, and the terminal voltage of the motor Is disclosed in which the power is controlled to be equal to or lower than the maximum output voltage of the power converter. In Non-Patent Document 1, this is called “weakening magnetic flux control”.
Hereinafter, problems when the control method described in Non-Patent Document 1 is applied to SPMSM will be described.
First, there is a relationship of Formulas 1 and 2 between the torque and magnetic flux of PMSM and the d and q axis currents.

In Equations 1 and 2, τ: torque, i _d : d-axis current, i _q : q-axis current, Ψ: magnetic flux, Ψ _d : d-axis magnetic flux, Ψ _q : q-axis magnetic flux, L _d : d-axis inductance , L _q : q-axis inductance, Ψ _m : magnetic flux of the permanent magnet.
On the other hand, there is a relationship of Formula 3 between the magnetic flux and the terminal voltage of the electric motor.

Incidentally, in Equation 3, _{V a:} terminal voltage _{amplitude, v} d: d-axis _{voltage, v} q: q-axis voltage, omega _1: speed detection value (electrical angular velocity), _{r a:} is armature resistance.

As shown in Equations 1 and 2, PMSM torque and magnetic flux are non-linear functions of d and q axis currents. However, since the d-axis inductance and the q-axis inductance are equal in SPMSM, the torque and the q-axis current are in a proportional relationship, and torque control can be performed relatively easily.
Further, when the voltage drop due to the armature resistance can be ignored, the torque control and the terminal voltage control can be easily realized because the magnetic flux and the terminal voltage are in a proportional relationship.

However, since the voltage drop due to the armature resistance is normally a value that cannot be ignored, it is extremely difficult to control the SPMSM terminal voltage to a desired value by magnetic flux control.
In addition, since the current control method described in Non-Patent Document 1 uses the electric constant of the electric motor for calculation, if there is an error in the electric constant, a control error occurs in the torque and terminal voltage. In particular, if the command value of the terminal voltage becomes higher than the maximum output voltage of the power converter, not only will a control error occur in the current and the torque control error will increase, but the current control system may become unstable. is there.
Even if there is an error in the electrical constant, the current control system can be stabilized if the current is controlled so that the terminal voltage is always below the maximum output voltage of the power converter. Since it is necessary to increase the current in order to obtain an output, there is a problem that the maximum speed and the maximum output are reduced due to power converter restrictions as well as efficiency.

Techniques for solving the above problems are described in Patent Document 1 and Patent Document 2.
First, an outline of the technique described in Patent Document 1 will be described.
In Patent Document 1, the d-axis current command value is calculated by an approximate function of the torque command value so that the torque / current becomes maximum. When the voltage command value exceeds the voltage limit value, a deviation between the voltage limit value and the voltage command value is amplified to calculate a d-axis current command correction signal, which is added to the d-axis current command value to obtain d Correct the shaft current command value. On the other hand, the q-axis current command value is calculated from the torque command value and the d-axis current command value to a value that outputs a desired torque.

  The above control can minimize the PMSM current under all operating conditions. In addition, since the terminal voltage can be controlled below the limit value, stable current control and highly accurate torque control can be realized even when the terminal voltage is controlled to the maximum output voltage of the power converter.

Next, an outline of the technique described in Patent Document 2 will be described.
In Patent Document 2, when the voltage command value (in the document, | V |) exceeds the voltage limit value (also | V | _fix ), the deviation between the voltage command value and the voltage limit value is amplified to correct the magnetic flux. Is calculated and added to the magnetic flux command value to correct the magnetic flux command value. The magnetic flux and the d-axis current are approximated to have a proportional relationship, and the d-axis current command value is calculated from the magnetic flux command value by this approximate expression. The q-axis current command value is calculated from the torque command value and the d-axis current command value to a value that outputs a desired torque.

  By the above control, the terminal voltage of the PMSM can be controlled to the maximum output voltage of the power converter mainly in the speed region above the base speed. Realized.

Japanese Patent No. 3686987 (paragraphs [0016] to [0066], FIG. 1 etc.) Japanese Patent No. 3230975 (paragraphs [0196] to [0205], FIG. 21 and the like) Yoji Takeda, Nobuyuki Matsui, Shigeo Morimoto, Yukio Honda, “Design and Control of Embedded Magnet Synchronous Motors”, Ohm, October 25, 2001, p.22-p.27

The prior art disclosed in Patent Document 1 is suitable for IPMSM control. However, when applied to the control of SPMSM, the configuration becomes more complex than necessary, and there is a problem that the cost of the control device increases.
The prior art disclosed in Patent Document 2 is applicable to PMSM in which the q-axis magnetic flux is sufficiently smaller than the magnetic flux of the permanent magnet and the magnetic flux and the d-axis current are in a substantially proportional relationship.
However, when applied to SPMSM where the q-axis magnetic flux cannot be ignored, the magnetic flux and the d-axis current are not necessarily in a proportional relationship, so the terminal voltage cannot be accurately controlled and the control system may become unstable. .

  Therefore, the problem to be solved by the present invention is that stable current control and highly accurate torque control are possible even when the terminal voltage of the motor is controlled to the maximum output voltage of the power converter, and in particular, the q-axis magnetic flux cannot be ignored. It is another object of the present invention to provide a control device for a permanent magnet type synchronous motor that can control the terminal voltage and torque of a large SPMSM with high accuracy, simplify control calculations, and reduce costs.

In order to solve the above problems, the invention according to claim 1 is a control device in which the terminal voltage of the permanent magnet synchronous motor is controlled to a voltage command value by a semiconductor power converter.
Input voltage detecting means for detecting an input voltage of the power converter; voltage limit value calculating means for calculating a voltage limit value equal to or lower than a maximum output voltage of the power converter from a detected value of the input voltage; and the voltage command value Voltage amplitude calculation means for calculating the amplitude of the current, current command calculation means for calculating a current command value from the voltage limit value, the amplitude of the voltage command value, and a torque command value, and the current of the motor as the current command value Current adjusting means for calculating a voltage command value to be applied to the power converter for control, and
The current command calculation means includes
Q-axis current command value calculating means for calculating a q-axis current command value from the torque command value; and magnetic flux adjusting means for calculating a magnetic flux correction value by amplifying a deviation between the voltage limit value and the amplitude of the voltage command value. Adding means for calculating the second magnetic flux limit value by adding the first magnetic flux limit value and the magnetic flux correction value; and the d-axis current limit value from the second magnetic flux limit value and the q-axis current command value. D-axis current limit value calculating means for calculating, and limiting means for limiting an upper limit value of the d-axis current command value by the d-axis current limit value.
In the present invention, since the d-axis current limit value is calculated in consideration of the influence of the q-axis magnetic flux generated by the q-axis current, the voltage control and torque control of the SPMSM in which the q-axis magnetic flux cannot be ignored, which is difficult in the prior art. Is possible. In addition, since the configuration is specialized for SPMSM control, the calculation is relatively easy, which can contribute to cost reduction of the control device.

  The invention according to claim 2 is obtained by replacing the method of correcting the magnetic flux limit value according to the invention of claim 1 with another method, and multiplying the magnetic flux limit value by the magnetic flux correction value to obtain the second value. The magnetic flux limit value is calculated.

  The invention according to claim 3 is obtained by adding a function of calculating the magnetic flux limit value in proportion to the voltage limit value to the control device according to claim 1 or 2. This improves the magnetic flux response when the voltage limit value changes.

  According to a fourth aspect of the present invention, the function of calculating the magnetic flux limit value in inverse proportion to the speed of the electric motor is added to the control device according to any one of the first to third aspects. This improves the magnetic flux response when the speed of the motor changes.

According to the present invention, stable current control and high-accuracy torque control can be achieved even when the terminal voltage of the permanent magnet type synchronous motor is controlled to a voltage limit value or less and the terminal voltage is controlled to the maximum output voltage of the power converter. Can be realized. In particular, the present invention is useful for terminal voltage control and torque control of SPMSM having a large q-axis magnetic flux, which has been difficult in the past, and by specializing in control of SPMSM, the calculation is simplified and the cost of the control device is reduced. be able to.
The present invention is also applicable to so-called sensorless control in which the magnetic pole position and speed are estimated and calculated from the current and terminal voltage of the electric motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of this embodiment.
In FIG. 1, the input voltage detection circuit 12 detects the input voltage E _dc of the power converter 70. The magnetic pole position detector 90 detects the magnetic pole position θ ₁ of the permanent magnet type synchronous motor 80, and the speed detector 91 detects the speed ω ₁ of the motor 80.

The deviation between the speed command value ω ^* and the detected speed value ω ₁ is calculated by the subtractor 16, and this deviation is amplified by the speed regulator 17 to calculate the torque command value τ ^* .
From the torque command value τ ^* , the voltage limit value V _alim , the voltage command value amplitude V _a ^*, and the speed detection value ω ₁ described later, the current command calculation unit 18 calculates torque / current under the condition that the terminal voltage is less than the voltage limit value. The d and q axis current command values i _d ^* and i _q ^* are calculated so as to be maximum and to output a desired torque. Here, the speed detection value ω ₁ is used when calculating the magnetic flux limit value Ψ _lim0 in a fourth embodiment described later.

Voltage limit value calculation unit 22 is substantially proportional to the input voltage E _dc, and calculates the voltage limit value V _alim such that the maximum output voltage of the power converter 70 determined by the input voltage E _dc below.
Further, the voltage amplitude calculator 21 calculates the voltage command value amplitude V _a ^{* according} to Equation 4 from the vector sum of the d and q axis voltage command values v _d ^* and v _q ^* .

The current coordinate converter 14 converts the u and w phase current detection values i _u and i _w detected by the u phase current detector 11u and the w phase current detector 11w, respectively, to d, q based on the magnetic pole position detection value θ _1. Coordinates are converted to detected shaft current values i _d and i _q .
The deviation between the d-axis current command value i _d ^* and the d-axis current detection value i _d calculated by the subtractor 19a, the deviation is amplified by a d-axis current regulator 20a d axis voltage value v _d ^* Calculate. On the other hand, a deviation between the q-axis current command value i _q ^* and the q-axis current detection value i _q is calculated by the subtractor 19b, and this deviation is amplified by the q-axis current regulator 20b to be q-axis voltage command value v _q. ^* Is calculated.
These d and q axis voltage command values v _d ^* and v _q ^* are converted into phase voltage command values v _u ^* , v _v ^* , and v _w ^* by the voltage coordinate converter 15 based on the magnetic pole position detection value θ _1. The

The rectifier circuit 60 rectifies the three-phase AC voltage of the three-phase AC power supply 50 to convert it into a DC voltage, and supplies the DC voltage to a power converter 70 such as an inverter.
The PWM circuit 13 uses the phase voltage command values v _u ^* , v _v ^* , v _w ^* and the input voltage detection value E _dc to convert the output voltage of the power converter 70 from the phase voltage command values v _u ^* , v _v ^* , A gate signal for controlling to v _w ^* is generated. The power converter 70 controls the internal semiconductor switching element based on the gate signal, thereby controlling the terminal voltage of the permanent magnet type synchronous motor 80 to the phase voltage command values v _u ^* , v _v ^* , v _w ^* . .

Next, a first embodiment of the current command calculation unit 18 in FIG. 1 will be described. FIG. 2 is a block diagram showing the first embodiment, and reference numeral 18A is given to the current command calculation section.
In FIG. 2, a q-axis current command calculator 131 calculates a q-axis current command value i _q ^* using Equation 5 from a relational expression between torque and q-axis current.

On the other hand, the first magnetic flux limit value Ψ _lim0 is set by Equation 6.
In Equation 6, ω _{base is a} base angular velocity, and V _{alim0 is a} rated voltage limit value.

In addition, the deviation between the voltage limit value V _alim and the voltage command value amplitude V _a ^* is calculated by the subtractor 121, and this is amplified by the magnetic flux regulator 122 to calculate the magnetic flux correction value Ψ _comp . The magnetic flux regulator 122 is constituted by, for example, an integral regulator.
Here, the magnetic flux correction value Ψ _comp is limited to zero or less by the output limiter 123 whose upper limit value is “0.0 (zero)” and is output.

Next, the adder 124 adds the magnetic flux correction value Ψ _comp to the first magnetic flux limit value Ψ _lim0 to obtain the second magnetic flux limit value Ψ _lim . Thereby, the magnetic flux limit value Ψ _lim that controls the terminal voltage of the electric motor 80 to be equal to or lower than the voltage limit value V _alim can be calculated.

The d-axis current limit value calculator 132 calculates the d-axis current limit value i _dlim from the q-axis current command value i _q ^* and the magnetic flux limit value Ψ _{lim according} to Equation 7.

The d-axis current limit value i _dlim is given as an upper limit value to the output limiter 133, and the first d-axis current command value i _d0 ^* limited by the upper limit value is the second d-axis current command value. Output as i _d ^* . The first d-axis current command value i _d0 ^* can be set to an arbitrary value. For example, when the torque / current is maximized, it is set to zero.
With the function described above, it is possible to calculate the d and q axis current command values i _d ^* and i _q ^* that control the terminal voltage of the electric motor 80 to be equal to or lower than the voltage limit value V _alim and output a desired torque. it can. In addition, since the influence of the q-axis magnetic flux (L _q i _q ^* ) generated by the q-axis current is taken into account in the calculation of the d-axis current limit value i _dlim according to Equation 7, the q-axis is difficult with the conventional technology. SPMSM voltage control and torque control in which the magnetic flux cannot be ignored is possible.

FIG. 3 is a block diagram showing a second embodiment of the current command calculation unit 18 in FIG. 1, and the current command calculation unit is denoted by reference numeral 18B.
In this embodiment, the method of calculating the second magnetic flux limit value Ψ _lim from the first magnetic flux limit value Ψ _lim0 in the first embodiment of FIG. 2 is replaced with another method. Here, only the parts different from the first embodiment will be described, and the description of the same parts will be omitted.

In the second embodiment, the upper limit value of the output limiter 123a provided on the output side of the magnetic flux regulator 122 is set to “1.0”, and the lower limit value is set to “0.0” to obtain the magnetic flux correction coefficient K _Ψ . The magnetic flux correction coefficient K _Ψ is multiplied by the first magnetic flux limit value Ψ _lim0 by the multiplier 125 to obtain the second magnetic flux limit value Ψ _lim .
With the above-described configuration, the second magnetic flux limit value Ψ _lim is controlled to a value that has a lower limit value of zero and an upper limit value of the first magnetic flux limit value Ψ _lim0 . The magnetic flux limit value Ψ _lim for controlling the terminal voltage to be equal to or lower than the voltage limit value V _alim can be calculated.
Other operations are the same as those in the first embodiment.

Next, FIG. 4 is a block diagram showing a third embodiment of the current command calculation unit 18 in FIG. 1, and reference numeral 18C is given to the current command calculation unit.
The third embodiment, the second embodiment of FIG. 3, is obtained by adding a function of calculating a first flux limit value [psi _Lim0 according to the voltage limit value V _alim, whereby the voltage limit value V _alim Improved the magnetic flux response when changes occur. Here, only the parts different from the second embodiment will be described, and the description of the same parts will be omitted.

That is, the magnetic flux limit value calculator 141 calculates the first magnetic flux limit value Ψ _lim0 proportional to the voltage limit value V _{alim according} to Equation 8, and gives this magnetic flux limit value Ψ _lim0 to the multiplier 125 to provide the magnetic flux correction coefficient K. _A second magnetic flux limit value Ψ _lim is obtained by multiplication with Ψ. The subsequent operation is the same as in the second embodiment.

Incidentally, the idea of calculating the first magnetic flux limit value [psi _Lim0 according to the voltage limit value V _alim as described above, is also applicable to the first embodiment of FIG. 2 as well as the second embodiment.

Next, FIG. 5 is a block diagram showing a fourth embodiment of the current command calculation unit 18 in FIG. 1, and reference numeral 18D is given to the current command calculation unit.
The fourth embodiment, in the third embodiment of FIG. 4, which has a first magnetic flux limit value [psi _Lim0 improved to compute in inverse proportion to the speed detection value omega ₁ of the electric motor 80, the magnetic flux limit value The speed detection value ω ₁ is also input to the calculator 141.
In other words, the magnetic flux limit value calculator 141 calculates the first magnetic flux limit value Ψ _lim0 using Equation 9.
Since other operations are the same as those of the third embodiment, description thereof is omitted.

As a result, the first magnetic flux limit value Ψ _lim0 and thus the second magnetic flux limit value Ψ _lim change according to the detected speed value ω ₁ , so that the magnetic flux response when the speed of the motor 80 changes can be improved. it can.
In this embodiment, the speed command value ω ^* may be used instead of the speed detection value ω ₁ .
As described above, the idea of calculating the first magnetic flux limit value _Ψlim0 in inverse proportion to the speed of the electric motor 80 can be applied not only to the third embodiment but also to the first and second embodiments.

It is a block diagram which shows the whole structure of embodiment of this invention. It is a block diagram which shows the 1st Example of the current command calculating part in FIG. It is a block diagram which shows the 2nd Example of the current command calculating part in FIG. It is a block diagram which shows the 3rd Example of the current command calculating part in FIG. It is a block diagram which shows the 4th Example of the current command calculating part in FIG.

Explanation of symbols

11u u-phase current detection circuit 11w w-phase current detection circuit 12 input voltage detection circuit 13 PWM circuit 14 current coordinate converter 15 voltage coordinate converters 16, 19a, 19b subtractor 17 speed controllers 18, 18A, 18B, 18C, 18D Current command calculation unit 20a d-axis current regulator 20b q-axis current regulator 21 voltage amplitude calculator 22 voltage limit value calculator 50 three-phase AC power supply 60 rectifier circuit 70 power converter 80 permanent magnet synchronous motor 90 magnetic pole position detector 91 Speed detector 121 Subtractor 122 Magnetic flux regulators 123, 123a, 133 Output limiter 124 Adder 125 Multiplier 131 q-axis current command calculator 132 d-axis current limit calculator 141 Magnetic flux limit calculator

Claims (4)

In the control device that controls the terminal voltage of the permanent magnet type synchronous motor to the voltage command value by the semiconductor power converter,
Input voltage detection means for detecting an input voltage of the power converter;
Voltage limit value calculating means for calculating a voltage limit value below the maximum output voltage of the power converter from the detected value of the input voltage;
Voltage amplitude calculating means for calculating the amplitude of the voltage command value;
Current command calculation means for calculating a current command value from the voltage limit value, the amplitude of the voltage command value, and a torque command value;
Current adjusting means for calculating a voltage command value to be supplied to the power converter in order to control the current of the motor to the current command value;
The current command calculation means includes
Q-axis current command value calculating means for calculating a q-axis current command value in a direction orthogonal to the magnetic pole direction of the permanent magnet of the electric motor from the torque command value;
Magnetic flux adjusting means for amplifying a deviation between the voltage limit value and the amplitude of the voltage command value to calculate a magnetic flux correction value;
Adding means for calculating a second magnetic flux limit value by adding the first magnetic flux limit value and the magnetic flux correction value;
D-axis current limit value calculating means for calculating a d-axis current limit value for limiting a d-axis current parallel to the magnetic pole direction of the permanent magnet of the electric motor from a second magnetic flux limit value and the q-axis current command value; ,
Limiting means for limiting an upper limit value of the d-axis current command value by the d-axis current limit value;
A control device for a permanent magnet type synchronous motor. In the control device that controls the terminal voltage of the permanent magnet type synchronous motor to the voltage command value by the semiconductor power converter,
Input voltage detection means for detecting an input voltage of the power converter;
Voltage limit value calculating means for calculating a voltage limit value below the maximum output voltage of the power converter from the detected value of the input voltage;
Voltage amplitude calculating means for calculating the amplitude of the voltage command value;
Current command calculation means for calculating a current command value from the voltage limit value, the amplitude of the voltage command value, and a torque command value;
Current adjusting means for calculating a voltage command value to be supplied to the power converter in order to control the current of the motor to the current command value;
The current command calculation means includes
Q-axis current command value calculating means for calculating a q-axis current command value in a direction orthogonal to the magnetic pole direction of the permanent magnet of the electric motor from the torque command value;
Magnetic flux adjusting means for amplifying a deviation between the voltage limit value and the amplitude of the voltage command value to calculate a magnetic flux correction value;
Multiplication means for calculating a second magnetic flux limit value by multiplying the first magnetic flux limit value and the magnetic flux correction value;
D-axis current limit value calculating means for calculating a d-axis current limit value for limiting a d-axis current parallel to the magnetic pole direction of the permanent magnet of the electric motor from a second magnetic flux limit value and the q-axis current command value; ,
Limiting means for limiting an upper limit value of the d-axis current command value by the d-axis current limit value;
A control device for a permanent magnet type synchronous motor. In the control device for a permanent magnet type synchronous motor according to claim 1 or 2,
A control device for a permanent magnet type synchronous motor, wherein the first magnetic flux limit value is calculated in proportion to the voltage limit value. In the control apparatus for the permanent magnet type synchronous motor according to any one of claims 1 to 3,
A control device for a permanent magnet type synchronous motor, wherein the first magnetic flux limit value is calculated in inverse proportion to the speed of the motor.

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