JP5104239B2 - Control device for permanent magnet type synchronous motor - Google Patents

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, so that the output is more controlled than the SPMSM by optimally controlling the current. 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, Non-Patent Document 1 describes a technique for controlling the d-axis current to an operating point that maximizes the torque / current by utilizing the reluctance torque of IPMSM. This is called “maximum torque / current control”.
Moreover, 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 set to the maximum output of the power converter. A technique for controlling the voltage below the voltage is also disclosed. In Non-Patent Document 1, this is called “weakening magnetic flux control”.

Next, problems in realizing the control method described in Non-Patent Document 1 will be described.
First, there is a relationship of Formulas 1 and 2 between the torque and magnetic flux of the IPMSM 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, torque and magnetic flux are non-linear functions of d and q axis currents. From Equation 3, in order to accurately control the terminal voltage, it is necessary to control the magnetic flux in consideration of the voltage drop due to the armature resistance.
For these reasons, it is extremely difficult to calculate d and q-axis current command values that can control the torque and terminal voltage of the IPMSM to desired values.

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.

  With the above control, the current of the IPMSM can be minimized 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 IPMSM can be controlled to the maximum output voltage of the power converter mainly in the speed region above the base speed. At this time, stable current control and high-accuracy torque control can be performed. Realized.

In addition, the control apparatus described in patent document 3 is known as another prior art regarding the control apparatus of the synchronous motor using reluctance torque.
The control device includes a torque calculation unit that calculates torque from the d-axis current command value and the q-axis current command value, a load angle adjustment unit that calculates a load angle so that the torque calculation value matches the torque command value, Coordinate conversion means for calculating a d-axis current command value and a q-axis current command value from the magnetic flux command value and the load angle is provided.

Japanese Patent No. 3686987 (paragraphs [0016] to [0066], FIG. 1 etc.) Japanese Patent No. 3230975 (paragraphs [0196] to [0205], FIG. 21 and the like) Japanese Patent No. 3640120 (Claim 6, paragraph [0050], FIG. 1, FIG. 8, etc.) Yoji Takeda, Nobuyuki Matsui, Shigeo Morimoto, Yukio Honda, “Design and Control of Embedded Magnet Synchronous Motors”, Ohm, October 25, 2001, p.22-p.27

In the conventional techniques disclosed in Patent Document 1 and Patent Document 2, both control the magnetic flux and control the terminal voltage by controlling the d-axis current. Therefore, the present invention can be applied 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 PMSM in which 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 to improve the control device according to Patent Document 3 described above, and in particular, to make it possible to control the terminal voltage and torque of the PMSM, which are so large that the q-axis magnetic flux cannot be ignored, with high accuracy. The object is to provide a control device for a magnet-type synchronous motor.

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 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
Magnetic flux command calculating means for calculating a first magnetic flux command value 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;
Output limiting means for limiting the upper limit of the magnetic flux correction value to zero;
Adding means for calculating a second magnetic flux command value by adding the first magnetic flux command value and the magnetic flux correction value whose upper limit value is restricted by the output restriction means ;
Torque calculating means for calculating torque from the current command value;
A load angle adjusting means for amplifying a deviation between the torque command value and the torque calculation value to calculate a load angle command value;
Current command generating means for calculating the current command value from a second magnetic flux command value and the load angle command value.

The invention according to claim 2 is obtained by replacing the method of correcting the magnetic flux command value in the invention according to claim 1 with another method.
That is, the magnetic flux correction coefficient is calculated by amplifying the deviation between the voltage limit value and the voltage command value amplitude, and this is multiplied by the first magnetic flux command value to calculate the second magnetic flux command value.

  The invention according to claim 3 is obtained by adding a function of changing the upper limit value of the magnetic flux command 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.

  The invention according to claim 4 is obtained by adding a function of changing the upper limit value of the magnetic flux command value in inverse proportion to the speed of the electric motor to the control device according to any one of claims 1 to 3. 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 PMSM having a large q-axis magnetic flux, which has been difficult in the past.
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 , the current command calculation unit 18 calculates torque / current under the condition that the terminal voltage is equal to or 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 _lim in the 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 the first embodiment, the magnetic flux correction value Ψ _comp ^* is obtained by using the deviation between the voltage limit value V _alim and the voltage command value amplitude V _a ^* in the configuration described in FIG. A function of calculating and correcting the magnetic flux command value Ψ ₀ ^* by the magnetic flux correction value Ψ _comp ^* is added.

In FIG. 2, a magnetic flux command calculator 111 calculates a first magnetic flux command value Ψ ₀ ^* from a torque command value τ ^* . The magnetic flux command value Ψ ₀ ^* is calculated under the condition that the torque / current is maximized, but it is difficult to perform this calculation online. Therefore, a magnetic flux command value table that maximizes torque / current is prepared in the magnetic flux command calculator 111 in advance, and the first magnetic flux command value Ψ ₀ ^* is calculated using this table during operation.

On the other hand, 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 deviation is amplified by the magnetic flux controller 122 to calculate the magnetic flux correction value Ψ _comp ^* . The magnetic flux regulator 122 is constituted by an integral regulator, for example.
Further, the magnetic flux correction value Ψ _comp ^* is output by being limited to zero or less by the output limiter 123 whose upper limit value is “0.0 (zero)”.

Next, the adder 124 adds the magnetic flux correction value ψ _comp ^* to the first magnetic flux command value ψ ₀ ^* to obtain the second magnetic flux command value ψ ^* . Thereby, the magnetic flux command value Ψ ^* 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 load angle adjuster 132 amplifies the deviation between the torque command value τ ^* calculated by the subtractor 131 and the torque calculation value τ _calc to calculate the load angle command value δ ^* . The load angle adjuster 132 is constituted by, for example, a proportional integration amplifier.

The torque calculator 134 calculates the torque calculation value τ _calc using Equation 5 using the d and q-axis current command values i _d ^* and i _q ^* and the constants L _d , L _q and Ψ _m .

The current command generator 133 calculates d, q-axis magnetic flux command values Ψ _d ^* , Ψ _q ^* from the magnetic flux command value Ψ ^* and the load angle command value δ ^*, and further, these magnetic flux command values Ψ _d ^* , D and q-axis current command values i _d ^* and i _q ^* are calculated from Ψ _q ^* . The arithmetic expressions are Expression 6 and Expression 7, respectively.

As described above, in this embodiment, the first magnetic flux command value Ψ ₀ ^* that maximizes the torque / current is calculated, and the magnetic flux correction value calculated using the magnetic flux regulator 122 and the output limiter 123 is calculated. [psi _comp ^* first obtains a magnetic flux command value [psi ₀ ^* second magnetic flux command value by correcting the [psi ^* by, d on the basis of the magnetic flux command value [psi ^*, q-axis current command value _i ^d *, _{i q} ^* Is calculated.
As a result, the terminal voltage is controlled to be equal to or lower than the maximum output voltage of the power converter 70 and the torque is controlled with high accuracy even for PMSM in which the q-axis magnetic flux is large and the magnetic flux and the d-axis current are not proportional. Can do.

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 command value Ψ ^* from the first magnetic flux command value Ψ ₀ ^* 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 command value ψ ₀ ^* by the multiplier 125 to obtain the second magnetic flux command value ψ ^* .
With the above configuration, the second magnetic flux command value Ψ ^* is controlled to a value that has a lower limit value of zero and an upper limit value equal to the first magnetic flux command value Ψ ₀ ^*, and the electric motor 80 is the same as in the first embodiment. The magnetic flux command value Ψ ^* for controlling the terminal voltage of the current to a voltage limit value V _alim or less 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.
In the third embodiment, a function for changing the upper limit value of the first magnetic flux command value Ψ ₀ ^* in accordance with the voltage limit value V _alim is _added to the second embodiment shown in FIG. The magnetic flux response when the limit value V _alim is changed is improved. Here, only the parts different from the second embodiment will be described, and the description of the same parts will be omitted.

First, the magnetic flux limit value calculator 141 calculates a magnetic flux limit value Ψ _lim that is proportional to the voltage limit value V _alim by Equation 8. In Equation 8, ω _base is a base angular velocity.

The upper limit value of the first magnetic flux command value Ψ ₀ ^* output from the magnetic flux command calculator 111 is limited by the output limiter 142 by the magnetic flux limit value Ψ _lim and input to the multiplier 125.
The subsequent operation is the same as in the second embodiment.
The _idea of _obtaining the magnetic flux limit value Ψ _lim according to the voltage limit value V _alim as described above and changing the upper limit value of the first magnetic flux command value Ψ ₀ ^* by this magnetic flux limit value Ψ _lim is the second embodiment. The present invention is applicable not only to the example but also to the first embodiment of FIG.

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.
In the fourth embodiment, the magnetic flux limit value Ψ _lim is changed in inverse proportion to the speed detection value ω ₁ in the third embodiment of FIG. The detection value ω _{1 is} also input.
In other words, the magnetic flux limit value calculator 141 calculates the magnetic flux limit value Ψ _lim by Equation 9.
Since other operations are the same as those of the third embodiment, description thereof is omitted.

As a result, the magnetic flux limit value Ψ _lim and thus the first magnetic flux command value Ψ ₀ ^* change according to the speed detection value ω ₁ , so that the magnetic flux response when the speed of the motor 80 changes can be improved.
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 _obtaining the magnetic flux limit value Ψ _lim in inverse proportion to the speed of the electric motor 80 and changing the upper limit value of the first magnetic flux command value Ψ ₀ ^* by this magnetic flux limit value Ψ _lim is the third embodiment. The present invention is applicable not only to the first embodiment and the second embodiment.

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 converter 16 subtractor 17 speed regulator 18, 18A, 18B, 18C, 18D current command calculation unit 19a subtractor 19b subtractor 20a d-axis current regulator 20b q-axis current regulator 21 voltage amplitude calculator 22 voltage limit 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 111 Magnetic flux command calculator 121 Subtractor 122 Magnetic flux adjusters 123 and 123a Output limiter 124 Adder 125 Multiplier 131 Subtractor 132 Load angle adjuster 133 Current command generator 134 Torque calculator 141 Magnetic flux limiter Value calculator 142 Output limiter

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
Magnetic flux command calculating means for calculating a first magnetic flux command value 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;
Output limiting means for limiting the upper limit of the magnetic flux correction value to zero;
Adding means for calculating a second magnetic flux command value by adding the first magnetic flux command value and the magnetic flux correction value whose upper limit value is restricted by the output restriction means ;
Torque calculating means for calculating torque from the current command value;
A load angle adjusting means for amplifying a deviation between the torque command value and the torque calculation value to calculate a load angle command value;
Current command generating means for calculating the current command value from a second magnetic flux command value and the load angle command 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
Magnetic flux command calculating means for calculating a first magnetic flux command value from the torque command value;
Magnetic flux adjusting means for calculating a magnetic flux correction coefficient by amplifying a deviation between the voltage limit value and the amplitude of the voltage command value;
Multiplying means for multiplying the first magnetic flux command value by the magnetic flux correction coefficient to calculate a second magnetic flux command value;
Torque calculating means for calculating torque from the current command value;
A load angle adjusting means for amplifying a deviation between the torque command value and the torque calculation value to calculate a load angle command value;
Current command generating means for calculating the current command value from a second magnetic flux command value and the load angle command 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 synchronous motor, wherein the upper limit value of the first magnetic flux command value is changed 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 apparatus for a permanent magnet type synchronous motor, wherein the upper limit value of the first magnetic flux command value is changed in inverse proportion to the speed of the motor.

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