JP5445892B2 - Control device for permanent magnet type synchronous motor - Google Patents

Description

  The present invention relates to a control device for a so-called sensorless controlled permanent magnet type synchronous motor without having a magnetic pole position detector for detecting the magnetic pole position of a rotor. The present invention relates to a control device that has been made possible.

Sensorless control of a permanent magnet type synchronous motor is widely put into practical use for the purpose of reducing the price of the control device. This sensorless control realizes torque control and speed control by calculating the rotor speed and magnetic pole position from information on the terminal voltage and armature current of the motor, and performing current control based on these.
Hereinafter, sensorless control methods described in Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2, which will be described later, will be described.

First, the permanent magnet synchronous motor realizes high-performance control by performing current control in a rotating coordinate system in which the magnetic pole direction of the rotor is defined as the d axis and the direction advanced 90 degrees from the d axis is defined as the q axis. Can do. However, when the magnetic pole position detector is not used, the angle of the dq axis cannot be directly detected. Therefore, a γδ axis rotation coordinate system corresponding to the dq axis rotation coordinate system is estimated inside the control device, and the dq axis component Current control is performed by converting the d-axis current i _d and the q-axis current i _q into γ-axis current i _γ and δ-axis current i _δ of the γδ-axis component.
FIG. 3 shows the relationship between the dq axis and the γδ axis described above, and θ _err is the angular difference between the dq axis and the γδ axis.

If the electrical angular velocity omega ₁ of the electrical angular velocity omega _r and γδ axes of the dq-axis are equal, the voltage equation of the permanent magnet synchronous motor in γδ axes is represented by Equation 1.

In Equation 1, the first term is the voltage drop due to the armature resistance r _a, the second term of the right side transient voltage proportional to the parallel current differential value d-axis inductance L _d, the third term on the right side voltage by armature reaction It is a descent.
Voltage drop due to the armature reaction in the third term on the right side is the voltage induced by the armature reaction magnetic flux which is the product of the armature current i _a and the q-axis inductance L _q, Advances the armature reaction magnetic flux 90 degrees Equal to the product of the vector and the electrical angular velocity ω ₁ of the γδ axis.
The fourth term on the right-hand side is a term called an expansion induced voltage (γδ axis components are respectively referred to as a γ-axis expansion induced voltage E _exγ and a δ-axis expansion induced voltage E _exδ ), and is expressed by Equation 2.

  As described in Non-Patent Document 2, which will be described later, the extended induced voltage has an effect of collecting the position information separated into the permanent magnet and the inductance of the permanent magnet type synchronous motor into one.

As shown in Equation 2, the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ are functions of the angle difference between the dq axis and the γδ axis (hereinafter also referred to as a magnetic pole position calculation error) θ _err , The position calculation error θ _err can be calculated from the angle of the γ-axis expansion induced voltage vector.

FIG. 4 is a vector diagram showing voltage equations of the permanent magnet type synchronous motor according to Equations 1 and 2. Note that the vector diagram of FIG. 4 is for normal rotation of the motor, and the expansion induced voltages E _exγ and E _exδ are generated in the q-axis direction.

Next, a method for calculating the speed ω ₁ and the magnetic pole position θ ₁ in the γδ axis rotation coordinate system will be described.
First, Equation 3 is obtained for the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _{exδ by modifying} Equation 1 described above.

Further, based on Equation 2, the magnetic pole position calculation error θ _err is calculated by Equation 4.

The speed calculation value (= γδ-axis electrical angular speed) ω ₁ can be obtained by a PI (proportional integration) adjuster having the magnetic pole position calculation error θ _err as an input.

The magnetic pole position calculation value θ ₁ is obtained by integrating the speed calculation value ω ₁ as shown in Equation 6.

By using Expressions 5 and 6, the magnetic pole position calculation error θ _err can be converged to zero, and the speed ω ₁ and the magnetic pole position θ ₁ can be accurately calculated.
If current control and speed control are performed using the speed ω ₁ and the magnetic pole position θ ₁ calculated in this way, the permanent magnet synchronous motor can be controlled with high performance without using a magnetic pole position detector.

Next, the sensorless control method described in Patent Document 2 will be described.
As described above, the sensorless control methods described in Patent Document 1 and Non-Patent Document 1 calculate the magnetic pole position calculation error θ _err from the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ using Equation 4. Yes. Here, since the amplitude E _ex of the expansion induced voltage is almost proportional to the speed ω _{1 as} shown in Equation 2, it is apparent that the calculation accuracy of the magnetic pole position calculation error θ _err is deteriorated at a low speed.
Therefore, in the sensorless control method according to Patent Document 2, the magnetic flux that induces the expansion induced voltage is newly defined as “expanded magnetic flux”.

The voltage induced by the magnetic flux at the terminal of the permanent magnet synchronous motor advances 90 degrees with respect to the magnetic flux, and its amplitude is the product of the speed and the magnetic flux. The d axis is defined, and the amplitude Ψ _ex is defined by Equation 7.

From Equation 2 and Equation 7, the amplitude Ψ _{ex of the} expanded magnetic flux is expressed by Equation 8.

FIG. 5 is a vector diagram showing the relationship between the expansion induced voltage and the expansion magnetic flux. From FIG. 5 and Expression 7, the γ-axis expansion induced voltage E _exγ , the δ-axis expansion induced voltage E _exδ , the γ-axis expansion magnetic flux Ψ _exγ , and the δ-axis expansion magnetic flux Ψ _exδ are in the relationship of Expression 9.

The relationship between the γ-axis expanded magnetic flux ψ _exγ and the δ-axis expanded magnetic flux ψ _exδ and the magnetic pole position calculation error θ _err is expressed by Equation 10 from Equation 2 and Equation 9.

From Equation 8, the amplitude Ψ _{ex of the} expanded magnetic flux is constant regardless of the speed ω ₁ in the steady state where the current differential value is zero. Therefore, be calculated if calculating the magnetic pole position calculation error theta _err using γ-axis expansion flux [psi _Exganma and δ-axis expansion flux [psi _Exderuta by Equation 10, the magnetic pole position calculation error theta _err even during low-speed high precision it can.

Next, a specific calculation method of the magnetic pole position and speed in Patent Document 2 will be described.
First, the δ-axis component Ψ _exδ of the expanded magnetic flux is calculated by Expression 11 from Expression 3 and Expression 9.

In Formula 10, when the magnetic pole position calculation error θ _err is a value near zero, the δ-axis expanded magnetic flux Ψ _exδ is _expressed by Formula 12.

Since the expanded magnetic flux amplitude Ψ _ex is a function of the d-axis current i _d and the q-axis current i _{q according} to Equation 8, the second δ-axis expanded magnetic flux ψ _{exδ obtained} by linearizing the δ-axis expanded magnetic flux ψ _exδ with Equation 13. 'Introduce.

The speed calculation value ω ₁ is obtained by Expression 14 using a PI controller as a speed calculator having the second extended magnetic flux Ψ _exδ ′ as an input.

The magnetic pole position calculation value θ ₁ is obtained by integrating the speed calculation value ω _{1 according} to Equation 6 described above.

In the sensorless control method described above, if the rotor speed and magnetic pole position calculation becomes unstable for some reason and the rotor steps out, the power converter that drives the permanent magnet synchronous motor is quickly stopped. Therefore, it is necessary to protect the power converter and the mechanical system of the load.
As a step-out detection technique for a permanent magnet type synchronous motor, for example, in Patent Document 3, a γδ axis voltage equation of the following Expression 15 (non-patent document) on the premise that the dq axis and the γδ axis substantially coincide with each other. The γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ are calculated by a disturbance observer derived from Equation (4) described in Document 2. Then, using the fact that the γ-axis expansion induced voltage E _exγ , which is zero when the dq axis and the γδ axis coincide, increases substantially in proportion to the angular difference between the dq axis and the γδ axis, A step-out is detected when the ratio between the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ exceeds a predetermined range.
Note that in Equation 15, _{K E} is the induced voltage constant.

Japanese Patent No. 3411878 (paragraphs [0026] to [0083], FIG. 1, etc.) JP 2006-67656 A (paragraphs [0023] to [0044], FIG. 1 and the like) Japanese Patent No. 3797508 (Claim 2, paragraphs [0013] to [0015], [0022] to [0026], FIG. 3, FIG. 4, etc.) Koji Tanaka, Ichiro Miki, “Position Sensorless Control of Embedded Magnet Synchronous Motor Using Extended Inductive Voltage”, IEEJ Transactions D, Vol.125, No.9, p.833-p.838 (2005) Shinji Ichikawa, Shiken Chen, Ikuo Hamada, Shinji Michiki, Shigeru Okuma, “Sensorless Control of Salient-Pole Permanent Magnet Synchronous Motor Based on Extended Induced Voltage Model”, IEEJ Transactions D, Vol.122, No.12 , P.1088-p.1096, 2002

The disturbance observer described in Patent Document 3 can be applied only when the angle difference between the dq axis and the γδ axis, that is, the magnetic pole position calculation error θ _err can be approximated to zero. In particular, in a permanent magnet synchronous motor having an embedded magnet structure with saliency on the rotor, since the inductances L _γ and L _δ in Equation 15 are functions of the magnetic pole position calculation error θ _err , the error θ _err is When the armature current is large, the calculation error of the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ according to Equation 15 increases.
For this reason, when the step-out detection technique described in Patent Document 3 is applied to a permanent magnet type synchronous motor having an embedded magnet structure, step-out cannot be accurately detected or step-out is erroneously detected. There was a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a permanent magnet synchronous motor that can accurately detect step-out even when a magnetic pole position calculation error is large or during low-speed operation.

In order to solve the above-mentioned problems, a control device for a permanent magnet type synchronous motor according to claim 1 is based on a permanent magnet type by a power converter based on a magnetic pole position of a rotor obtained by calculation without using a magnetic pole position detector. In the control device for controlling the armature current of the synchronous motor and controlling the torque and speed of the motor,
Taking the armature current, terminal voltage and magnetic flux of the motor as vectors,
Terminal voltage equivalent value of the motor, the armature resistance voltage drop calculation value, the speed of the previous SL transient voltage calculation value proportional to the time differential value of the armature current, and a vector which is advanced the armature reaction magnetic flux 90 degrees the motor An expanded magnetic flux calculating means for calculating an expanded magnetic flux using a product with the calculated value ;
An angle calculating means for calculating an angle of the expansion magnetic flux from a component parallel to the rotor magnetic pole of the expansion magnetic flux and a component orthogonal to the rotor magnetic pole of the expansion magnetic flux;
And step-out detecting means for detecting step-out of the electric motor from the angle of the expanded magnetic flux.

The control device for a permanent magnet type synchronous motor according to claim 2 is the control device for a permanent magnet type synchronous motor according to claim 1 ,
Current coordinate conversion means for converting the detected value of the armature current into a biaxial component of a rotating coordinate system using the magnetic pole position obtained from the expanded magnetic flux,
Current adjusting means for generating a voltage command value that matches the biaxial component with the biaxial component of the armature current command value;
Means for generating a drive signal for the semiconductor switching element of the power converter from the voltage command value .

  According to the control device for a permanent magnet synchronous motor according to the present invention, in the control device for sensorless control of the permanent magnet synchronous motor, the step-out in the case where the magnetic pole position calculation error is large or during the low speed operation of the motor is known. Therefore, the power converter and the load mechanical system can be reliably protected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 is a block diagram of the control device shown in conjunction with a main circuit according to a reference embodiment of the present invention.
In the main circuit shown in FIG. 1, 50 is a three-phase AC power source, 60 is a rectifier circuit that rectifies and converts a three-phase AC voltage into a DC voltage, 70 is a power converter such as an inverter, and 80 is a permanent magnet synchronous motor. .

Hereinafter, the configuration and operation of the control device will be described.
First, a method for controlling the speed of the permanent magnet synchronous motor 80 using the rotor speed calculation value ω ₁ and the magnetic pole position calculation value θ ₁ will be described.
A deviation between the speed command value ω ^* and the speed calculation value ω ₁ is calculated by the subtractor 16, and the deviation is amplified by the speed controller 17 to calculate the torque command value τ ^* . The current command calculator 18 calculates a γ-axis current command value i _γ ^* and a δ-axis current command value i _δ ^* that output a desired torque from the torque command value τ ^* .

On the other hand, u-phase current detector 11u, w-phase current detector phase current detection value i _u detected respectively by 11 _w, and i _w, gamma-axis current detection value by the current coordinate converter 14 by using the magnetic pole position calculation value theta ₁ Coordinates are converted to i _γ and δ-axis current detection values i _δ .
A deviation between the γ-axis current command value i _γ ^* and the detected γ-axis current value i _γ is obtained by a subtractor 19a, and this deviation is amplified by a γ-axis current regulator 20a to calculate a γ-axis voltage command value v _γ ^* . To do. Further, the deviation between the δ-axis current command value i _δ ^* and the δ-axis current detection value i _δ is obtained by the subtractor 19b, and this deviation is amplified by the δ-axis current regulator 20b to obtain the δ-axis voltage command value v _δ ^* . Calculate.
The voltage command values v _γ ^* and v _δ ^* are converted into phase voltage command values v _u ^* , v _v ^* and v _w ^* by the voltage coordinate converter 15.

The PWM circuit 13 turns on the semiconductor switching element in the power converter 70 from the phase voltage command values v _u ^* , v _v ^* , v _w ^* and the input voltage detection value E _dc detected by the input voltage detection circuit 12. Generate a gate signal for off control. The power converter 70 turns on and off the semiconductor switching element based on the gate signal, and controls the terminal voltage of the permanent magnet type synchronous motor 80 to the phase voltage command values v _u ^* , v _v ^* , and v _w ^* .

Next, in this reference embodiment, the configuration and operation for calculating the rotor speed ω ₁ and the magnetic pole position θ ₁ will be described.
The expansion induced voltage calculator 30 is expressed by the following equation 16 in which the γ-axis voltage v _γ and the δ-axis voltage v _δ in Equation 3 are replaced with the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^* . gamma-axis voltage value v _gamma ^*, [delta] -axis voltage value v _[delta] ^*, gamma-axis current detection value i _gamma, [delta]-axis current detection value i _[delta], velocity omega ₁ and an armature resistance _r a, d-axis inductance L _The γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ are calculated using motor constants such as _d and q-axis inductance L _q .

Since the inductances L _d and L _q in Expression 16 are not functions of the magnetic pole position calculation error θ _err unlike L _γ and L _δ in Expression 15, the magnetic pole position calculation error θ _err is zero according to Expression 16. Even when it is not in the vicinity, the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ can be accurately calculated.

In Equation 16, the second term on the right side is the voltage drop due to the armature resistance r _a, the third term on the right side transient voltage proportional to the parallel current differential value d-axis inductance L _d, fourth term on the right-hand side is the voltage due to armature reaction It is a descent.
Voltage drop due to the armature reaction of the fourth term on the right-hand side is a voltage induced by the armature reaction magnetic flux which is the product of the armature current i _a and the q-axis inductance L _q, Advances the armature reaction magnetic flux 90 degrees Equal to the product of the vector and the electrical angular velocity ω ₁ of the γδ axis.

Here, according to Equation 2 described above, the magnetic pole position calculation error θ _err can be obtained from the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ . Further, the angle δ _eex of the expansion induced voltage E _ex can be _obtained by Expression 17, and according to Expression 2, the angle δ _eex of the expansion induced voltage E _ex is equal to the magnetic pole position calculation error θ _err as shown in Expression 18. (An angle θ _err between the δ axis in FIG. 4 and the extended induced voltage vector E _ex is equal to δ _eex ).

Accordingly, the angle calculator 32 in FIG. 1 calculates the angle δ _eex of the extended induced voltage E _ex by the calculation of Expression 17, and this angle δ _eex is input to the speed calculator 33 and the step-out detector 35.
The speed calculator 33 is constituted by a PI controller, and a speed calculation value ω ₁ is obtained by amplifying the angle δ _eex of the expansion induced voltage E _ex using Expression 19.

The magnetic pole position calculator 34 is configured by an integrator, and the magnetic pole position calculation value θ ₁ is obtained by integrating the speed calculation value ω ₁ using the above-described Expression 6.
The step-out detector 35 detects step-out when the angle δ _eex of the expansion induced voltage E _ex exceeds a predetermined threshold value, and activates the step-out detection signal.
As shown in Equation 18, since the angle δ _eex and the magnetic pole position calculation error θ _err are equal in size, it is clear that the step-out detector 35 can detect the step-out from the size of the angle δ _eex .

According to this reference mode, the magnetic pole position calculation error θ _err is not approximated to zero as in Patent Document 3, so that even when the error θ _err is large, step-out can be accurately detected.

Next, the implementation form of the present invention will be described with reference to FIG. This embodiment corresponds to the inventions according to claims 1 and 2 .
As shown in FIG. 2, this embodiment is different from the reference embodiment in that an extended magnetic flux calculator 31 is provided instead of the extended induced voltage calculator 30 in FIG. 1, and the speed ω ₁ and the magnetic pole position θ ₁ are set as the extended induced voltage. The calculation accuracy is improved by calculating from the expanded magnetic flux, and the step-out detection accuracy is improved at the same time.
Note that the speed control method of the permanent magnet type synchronous motor 80 using the speed ω ₁ and the magnetic pole position θ ₁ is the same as that in the reference embodiment, and thus the description thereof will be omitted. Hereinafter, the calculation method of the speed ω ₁ and the magnetic pole position θ ₁ and A step-out detection method will be described.

2 uses the γ-axis expansion induced voltage E _exγ and the δ-axis expansion induced voltage E _exδ obtained by Expression 16, and the γ-axis expansion magnetic flux Ψ _exγ and δ-axis expansion magnetic flux by Expression 20. Ψ _exδ is calculated.

The angle calculator 32 calculates the angle δ _Ψex of the expanded magnetic flux Ψ _ex using Equation 21 using the γ-axis expanded magnetic flux Ψ _exγ and the δ-axis expanded magnetic flux Ψ _exδ .

From FIG. 5 described above, there is a relationship of Formula 22 between the angle δ _{Ψex of the} expanded magnetic flux and the magnetic pole position calculation error θ _err .

The speed calculator 33 is configured by a PI controller, and a speed calculation value ω ₁ is obtained by amplifying the expansion magnetic flux angle δ _Ψex using Expression 23.

The magnetic pole position calculator 34 is configured by an integrator, and the magnetic pole position calculation value θ ₁ is obtained by integrating the speed calculation value ω ₁ using the above-described Expression 6.

The step-out detector 35 detects step-out when the angle δ _{Ψex of the} expanded magnetic flux exceeds a predetermined threshold, and activates the step-out detection signal.
As shown in Expression 22, the angle δ _Ψex and the magnetic pole position calculation error θ _err are equal in magnitude, so it is clear that the step-out detector 35 can detect the step-out from the magnitude of the angle δ _Ψex .

The step-out detection in the reference embodiment described above uses the expansion induced voltage whose amplitude is approximately proportional to the rotor speed ω _{1 according} to Equation 2, so that the detection accuracy during low-speed operation may be low. On the other hand, in the embodiment of the present invention , since the extended magnetic flux whose amplitude is constant irrespective of the speed of the rotor is used, it is possible to detect the step-out with high accuracy even at a low speed.

It is a block diagram which shows the reference form of this invention. Is a block diagram showing an implementation form of the present invention. It is a figure which shows the relationship between a dq axis | shaft and a (gamma) delta axis | shaft. It is a vector diagram which shows the voltage equation of the permanent magnet type synchronous motor by Numerical formula 1 and Numerical formula 2. It is a vector diagram which shows the relationship between an expansion induced voltage and an expansion magnetic flux.

Explanation of symbols

50: Three-phase AC power supply 60: Rectifier circuit 70: Power converter 80: Permanent magnet synchronous motor 11u: u-phase current detection circuit 11w: w-phase current detection circuit 12: input voltage detection circuit 13: PWM circuit 14: current coordinates Converter 15: Voltage coordinate converters 16, 19a, 19b: Subtractor 17: Speed controller 18: Current command calculator 20a: γ-axis current controller 20b: δ-axis current controller 30: Extended induced voltage calculator 31: Expanded magnetic flux calculator 32: Angle calculator 33: Speed calculator 34: Magnetic pole position calculator 35: Step-out detector

Claims (2)

In a control device for controlling an armature current of a permanent magnet type synchronous motor by a power converter based on a magnetic pole position of a rotor obtained by calculation without using a magnetic pole position detector, and controlling a torque and a speed of the motor ,
Taking the armature current, terminal voltage and magnetic flux of the motor as vectors,
Terminal voltage equivalent value of the motor, the armature resistance voltage drop calculation value, the speed of the previous SL transient voltage calculation value proportional to the time differential value of the armature current, and a vector which is advanced the armature reaction magnetic flux 90 degrees the motor An expanded magnetic flux calculating means for calculating an expanded magnetic flux using a product with the calculated value ;
An angle calculating means for calculating an angle of the expansion magnetic flux from a component parallel to the rotor magnetic pole of the expansion magnetic flux and a component orthogonal to the rotor magnetic pole of the expansion magnetic flux;
Step-out detection means for detecting step-out of the electric motor from the angle of the expanded magnetic flux;
A control device for a permanent magnet type synchronous motor. In the control device for the permanent magnet type synchronous motor according to claim 1,
Current coordinate conversion means for converting the detected value of the armature current into a biaxial component of a rotating coordinate system using the magnetic pole position obtained from the expanded magnetic flux,
Current adjusting means for generating a voltage command value that matches the biaxial component with the biaxial component of the armature current command value;
Means for generating a drive signal for the semiconductor switching element of the power converter from the voltage command value;
A control device for a permanent magnet type synchronous motor.

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