JP4984057B2 - 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 synchronous motor without a magnetic pole position detector for detecting the magnetic pole position of a rotor, and more particularly, to increase the rotor speed and the magnetic pole position. The present invention relates to a control device that can stably control a permanent magnet synchronous motor by calculating the accuracy and controlling the armature current of the motor.

  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.

As a representative example of conventional sensorless control, the sensorless control methods described in Patent Document 1 and Non-Patent Document 1 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.

Here, FIG. 4 shows the relationship between the dq axis and the γδ axis, 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.

  The extended induced voltage has the effect of consolidating the position information separated into the permanent magnet and the inductance of the permanent magnet type synchronous motor into one, and is also described in Non-Patent Document 2, for example.

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 angles of the γ-axis expansion induced voltage vector E _exγ and the δ-axis expansion induced voltage E _exδ .

FIG. 5 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. 5 is for the 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, the magnetic pole position calculation error θ _err is calculated from Equation 2 using Equation 4.

The speed calculation value (= γδ-axis electrical angular speed ω ₁ ) can be obtained by a PI (proportional integration) adjuster that receives the magnetic pole position calculation error θ _err , and is specifically calculated by Equation 5.

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 type synchronous motor can be controlled with high performance without using a 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. ing. By the way, since the amplitude E _ex of the expansion induced voltage is almost proportional to the speed ω _{1 as} shown in Formula 2, it is clear that the calculation accuracy of the magnetic pole position calculation error θ _err deteriorates 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. 6 is a vector diagram showing the relationship between the expansion induced voltage and the expansion magnetic flux. 6 and Equation 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 Equation 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.

Japanese Patent No. 3411878 (paragraphs [0026] to [0083], FIG. 1, etc.) JP 2006-67656 A (paragraphs [0023] to [0044], FIG. 1 and the like) Koji Tanaka and 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

Since the sensorless control method shown in Patent Document 2 is a method that focuses on magnetic flux, there is an advantage that the speed ω ₁ and the magnetic pole position θ ₁ during low-speed operation can be calculated with high accuracy. And the problems of the prior art related to Non-Patent Document 1 are overcome.
However, since the speed ω ₁ and the magnetic pole position θ ₁ are calculated based on the approximate expression (Formula 12) when the magnetic pole position calculation error θ _err between the dq axis and the γδ axis is near zero, the magnetic pole position calculation error When θ _err is large, there is a problem that accurate calculation cannot be performed and the control system becomes unstable.

  Accordingly, a problem to be solved by the present invention is to provide a control device for a permanent magnet type synchronous motor that enables stable control by accurately calculating the rotor speed and the magnetic pole position even when the magnetic pole position calculation error is large. There is.

In order to solve the above-mentioned problem, a control device for a permanent magnet type synchronous motor according to claim 1 is configured to generate a current of a permanent magnet type synchronous motor 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 torque and speed of the permanent magnet type synchronous motor by controlling,
Taking the armature current, terminal voltage and magnetic flux of the motor as vectors,
The terminal voltage equivalent value of the motor, the armature resistance voltage drop calculation value and the armature reaction magnetic flux calculation value proportional to the armature current, the transient voltage calculation value proportional to the time differential value of the armature current, and the motor Extended induced voltage calculation means for calculating the extended induced voltage using the speed calculation value;
An expanded magnetic flux calculating means for calculating an expanded magnetic flux using the expanded induced voltage and the speed calculated value;
Angle calculating means for calculating the angle of the expanded magnetic flux from the expanded magnetic flux;
Speed calculating means for amplifying the angle of the expanded magnetic flux to obtain the speed calculation value;
Magnetic pole position calculation means for amplifying the speed calculation value to obtain a magnetic pole position calculation value;
It is equipped with.
In the present invention, since the extended magnetic flux is used for the calculation of the speed and the like, the speed and the magnetic pole position can be calculated with high accuracy even when the motor is operated at a low speed as compared with the prior arts disclosed in Patent Document 1 and Non-Patent Document 1. it can. Compared to the prior art according to Patent Document 2, even when the magnetic pole position calculation error is large, the calculation can be performed accurately.

The control device for a permanent magnet type synchronous motor according to claim 2 is characterized in the configuration of the expanded magnetic flux calculation means in claim 1.
That is, the invention according to claim 2 is the control device according to claim 1, wherein the extended magnetic flux calculating means divides a vector obtained by delaying the extended induced voltage by 90 degrees by the speed calculated value to obtain the extended magnetic flux. It is to calculate.

A control apparatus for a permanent magnet synchronous motor according to claim 3 is an improvement of the extended magnetic flux calculation means according to claim 2, wherein the extended magnetic flux calculation means includes a vector obtained by delaying the expansion induced voltage by 90 degrees and the The expansion magnetic flux is calculated by amplifying a deviation from the vector formed by multiplying the expansion magnetic flux and the speed calculation value.
In claim 2, the expanded magnetic flux is calculated by dividing by the speed calculated value. However, in the invention according to claim 3, the expanded magnetic flux is calculated without performing division by the speed calculated value. As a result, the extended magnetic flux at low speed, and hence the speed and magnetic pole position of the motor can be obtained with higher accuracy.

The control device according to claim 4 is the control device according to any one of claims 1 to 3,
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 calculated by the magnetic pole position calculation means;
Current adjusting means for generating a voltage command value so as to match the biaxial component of the detected value with the biaxial component of the command value of the armature current;
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 type synchronous motor, the speed and magnetic pole position at the time of low speed operation of the motor are calculated with higher accuracy than in the prior art. And can improve the stability during low-speed operation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a control device according to this embodiment together with a main circuit, and corresponds to the inventions according to claims 1 and 4.
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 magnetic pole position calculation value θ ₁ and the speed calculation value ω 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, the phase current detection values i _u and i _w detected by the u-phase current detector 11 _u and the w-phase current detector 11 _w are converted into the γ-axis current by the current coordinate converter 14 using the magnetic pole position calculation value θ _1. Coordinates are converted to detected values i _γ and δ-axis current detected 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 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 uses the γ-axis voltage v _γ and the δ-axis voltage v _δ in Equation 3 to replace the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^*. Using the command value v _γ ^* , the δ-axis voltage command value v _δ ^* , the γ-axis current detection value i _γ , the δ-axis current detection value i _δ , the speed ω ₁ and the motor constant, the γ-axis expansion induced voltage E _exγ , δ The shaft expansion induced voltage E _exδ is calculated.

Extended flux calculator 31, gamma shaft extension induction voltage _{E exγ,} using δ-axis extended electromotive force _{E Exderuta} and speed omega _1, gamma-axis expansion flux _Ψ exγ, calculates the δ-axis expansion flux Ψ _exδ. The specific configuration of the expanded magnetic flux calculator 31 will be described later.
Angle calculator 32, the angle [delta] _Pusaiex extended flux [psi _ex is calculated by Equation 15.

From Equation 10 described above, the expansion magnetic flux angle δ _Ψex and the magnetic pole position calculation error θ _err are in the relationship of Equation 16.

The speed calculator 33 is constituted by a PI controller, and a speed calculation value ω ₁ is obtained by amplifying the expansion magnetic flux angle δ _Ψex using Expression 17.

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.

Next, a specific configuration of the expanded magnetic flux calculator 31 will be described with reference to FIGS.
FIG. 2 is a block diagram showing a first embodiment of the expanded magnetic flux calculator 31 and corresponds to the invention according to claim 2.
Based on Expression 9, the extended magnetic flux Ψ _ex is calculated as Expression 18 by dividing a vector obtained by delaying the extended induced voltage E _ex by 90 degrees by the speed calculation value ω ₁ .

In FIG. 2, the calculation of Equation 18 is realized by a gain 31a and dividers 31b and 31c. Further, the noise components are removed by passing the outputs of the dividers 31b and 31c through the low-pass filters 31d and 31e, respectively, and the final γ-axis expanded magnetic flux ψ _exγ and δ-axis expanded magnetic flux ψ _exδ are obtained. These γ-axis expanded magnetic flux ψ _exγ and δ-axis expanded magnetic flux ψ _exδ are input to the angle calculator 32 as described above.

In the prior art according to Patent Document 2 described above, the magnetic pole position calculation error θ _err is approximated to be close to zero, and the δ-axis expanded magnetic flux Ψ _exδ is substantially proportional to the magnetic pole position calculation error θ _err as shown in Equation 12. Is used to calculate the speed ω ₁ and the magnetic pole position θ ₁ .
On the other hand, in the present embodiment, since the approximation as in Patent Document 2 is not performed, the γ-axis expanded magnetic flux Ψ _exγ and the δ-axis expanded magnetic flux Ψ _{exδ are} obtained regardless of the magnitude of the magnetic pole position calculation error θ _err. The speed ω ₁ and the magnetic pole position θ ₁ can be accurately detected based on the expanded magnetic flux angle δ _Ψex .

Next, a second embodiment of the expanded magnetic flux calculator 31 will be described with reference to FIG.
Compared with the first embodiment, the second embodiment is characterized in that the calculation of the expanded magnetic flux is realized without using a divider. This embodiment corresponds to the invention according to claim 3.

That is, in FIG. 3, E _exδ and −E _exγ that are components of a vector obtained by delaying the extended induced voltage vector E _ex by 90 degrees are input to the subtractors 31f and 31g, respectively, and the γ-axis expanded magnetic flux Ψ _exγ and the speed calculation are performed. The product of the value ω ₁ and the product of the δ-axis expanded magnetic flux Ψ _exδ and the speed calculation value ω ₁ are respectively calculated by the multipliers 31j and 31k. Then, the subtractor 31f _obtains the deviation between E _exδ and the output of the multiplier 31j and inputs it to the γ-axis expanded magnetic flux calculator 31h, and the subtractor 31g _obtains the deviation between −E _exγ and the output of the multiplier 31k. And input to the δ-axis expanded magnetic flux calculator 31i.

The γ-axis expanded magnetic flux calculation unit 31h and the δ-axis expanded magnetic flux calculation unit 31i calculate the γ-axis expanded magnetic flux ψ _exγ and the δ-axis expanded magnetic flux ψ _exδ by amplifying the respective input deviations. Here, the γ-axis expanded magnetic flux calculation unit 31h and the δ-axis expanded magnetic flux calculation unit 31i are configured by an integral controller.
When the expanded magnetic flux calculator according to the block diagram of FIG.

According to this embodiment, unlike the first embodiment, since the expansion induced voltage E _ex is not directly calculated by the speed calculation value ω ₁ and the expansion magnetic flux is calculated, the γ-axis expansion magnetic flux calculation units 31h and δ are not used. The γ-axis expanded magnetic flux Ψ _exγ and the δ-axis expanded magnetic flux Ψ _exδ can be converged to true values by the shaft expanded magnetic flux calculation unit 31i, and the expanded magnetic flux can be obtained with high accuracy even during low-speed operation. The rotor speed and magnetic pole position can be accurately calculated.

It is a block diagram which shows embodiment of this invention. It is a block diagram which shows 1st Example of an expansion magnetic flux calculator. It is a block diagram which shows 2nd Example of an expansion magnetic flux calculator. 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 31a: Gain 31b, 31c: Divider 31d, 31e: Low-pass filter 31f, 31g: Subtractor 31h: γ-axis expanded magnetic flux calculator 31i: δ-axis expanded flux calculator 31j, 31k: Multiplier 31: Expanded flux calculator 32: Angle Calculator 33: Speed calculator 34: Magnetic pole position calculator

Claims (4)

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,
The terminal voltage equivalent value of the motor, the armature resistance voltage drop calculation value and the armature reaction magnetic flux calculation value proportional to the armature current, the transient voltage calculation value proportional to the time differential value of the armature current, and the motor Extended induced voltage calculation means for calculating the extended induced voltage using the speed calculation value;
An expanded magnetic flux calculating means for calculating an expanded magnetic flux using the expanded induced voltage and the speed calculated value;
Angle calculating means for calculating the angle of the expanded magnetic flux from the expanded magnetic flux;
Speed calculating means for amplifying the angle of the expanded magnetic flux to obtain the speed calculation value;
Magnetic pole position calculation means for amplifying the speed calculation value to obtain a magnetic pole position calculation value;
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,
The expanded magnetic flux calculation means is
A control apparatus for a permanent magnet type synchronous motor, wherein the expansion magnetic flux is calculated by dividing a vector obtained by delaying the expansion induced voltage by 90 degrees by the speed calculation value. In the control device for the permanent magnet type synchronous motor according to claim 1,
The expanded magnetic flux calculation means is
Control of a permanent magnet synchronous motor, wherein the expansion magnetic flux is calculated by amplifying a deviation between a vector obtained by delaying the expansion induced voltage by 90 degrees and a vector obtained by multiplying the expansion magnetic flux and the speed calculation value. apparatus. In the control apparatus for the permanent magnet type synchronous motor according to any one of claims 1 to 3,
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 calculated by the magnetic pole position calculation means;
Current adjusting means for generating a voltage command value so as to match the biaxial component of the detected value with the biaxial component of the command value of the armature current;
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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