KR100848155B1 - Control Method of Permanent Magnet Synchronous Motor - Google Patents

Abstract

The present invention relates to a control method of a permanent magnet synchronous motor, and more particularly, to calculate the current estimation error by comparing the measured current value and the estimated current value of the motor model to estimate the motor current, and then calculating the back electromotive force and speed of the motor. The present invention relates to a control method of a permanent magnet type synchronous motor capable of reducing current measurement error and noise by estimating and detecting the position of a rotor.

The present invention provides a method for estimating the counter electromotive force of the motor, the speed and the position of the rotor through the estimation axes (δ, γ) for estimating the magnetic axis of the rotor, wherein the delta current estimation error (Δiδ) and gamma current estimation error ( Δiγ), calculate the estimated value of the back EMF of the motor through the delta current estimation error, calculate the speed estimate of the rotor, calculate the correction value through the gamma current estimation error, and then correct the correction to the speed estimate. Summing the values to calculate the speed correction estimate, and integrating the speed correction estimate to calculate the position of the rotor.

Description

Control Method of Permanent Magnet Synchronous Motor

1 is an illustration of a typical permanent magnet brushless direct current motor,

2 is a control block diagram of a permanent magnet synchronous motor according to an embodiment of the present invention,

3 is an algorithm response graph for reducing a back EMF constant according to an embodiment of the present invention,

4 is a flowchart illustrating a control method of a permanent magnet synchronous motor according to an exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

21: Proportional Integrator 22: Multiplier

23: first low pass filter 24: signal function

25: delay function 26: integrator

27: integral regulator 28: second low pass filter

29: model motor

The present invention relates to a control method of a permanent magnet synchronous motor, and more particularly, to calculate the current estimation error by comparing the measured current value and the estimated current value of the motor model to estimate the motor current, and then calculating the back electromotive force and speed of the motor. The present invention relates to a control method of a permanent magnet type synchronous motor capable of reducing current measurement error and noise by estimating and detecting the position of a rotor.

In general, in a motor using sensorless vector control, the phase to be excited to obtain the maximum torque during the rotation of the rotor is determined by the position of the rotor of the motor. Here, when the rotor is rotating, the position of the rotor can be measured according to the counter electromotive force. Based on this, the motor is rotated by selectively exciting an appropriate phase to obtain the maximum torque during the control of the motor.

A conventional motor using sensorless vector control is described in (1) IEEE Bulletin on Industrial Electronics, April 1996, Vol. 43, No. 2, pp. 300 to 308, published by N. Matsui. Permanent Magnet Brushless DC Motor Sensorless Drive "and Papers (2) Proc. IECON'92, 1992, pages 430-435, published by Matsui, Takeshita, and Yasuda, "New Sensorless Drives for Brushless DC Motors."

1 is a view disclosed in the paper (1), a conventional brushless DC motor will be described with reference to FIG. 1A.

U, V and W are the three phases of the motor, d and q are virtual axes, axis d is aligned along the rotor's magnetic axis and rotates with the rotor. (Ie, to reduce motor vibration)

In addition, since the rotor position is unknown, the gamma (γ) and delta (δ) axes are used to estimate the d and q axes. As described in the paper (1), the model motor is used to estimate the back-EMF of the rotor, and then the position and speed can be estimated using the following equations. (Here, the superscript is used to indicate the calculation step.)

Here, Ec is the motor back electromotive force, Δi _γ and Δi _δ is the difference between the current and the measured current estimated in the previous calculation step (n-1) based on the γ and δ axis, Ke is the motor back EMF constant, T is the sampling time.

The counter electromotive force calculation as described above uses two measurement values, current and DC voltage. Therefore, current measurement error and noise have a big influence on the estimation result, and the difference between the actual motor and the model motor parameter increases the estimation error, and the estimation error can increase in the transient period due to the difference between the actual motor and the model motor parameter. have.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to significantly reduce noise and measurement error, speed and position estimation error by using a low pass filter and an integral regulator when estimating back EMF. To provide a control method of a permanent magnet synchronous motor to prevent the increase of.

Another object of the present invention is to provide a control method of a permanent magnet synchronous motor capable of estimating motor position and speed even when a motor parameter changes.

It is another object of the present invention to provide a control method of a permanent magnet type synchronous motor including a correction algorithm so that the motor parameter estimation is accurate even when the motor parameter changes.

It is still another object of the present invention to provide a control method of a permanent magnet synchronous motor for minimizing rotor estimation errors that may occur in transient and steady state by calculating current errors through a delta axis and a gamma axis.

In order to achieve the above object, the technical method according to the present invention is a method for estimating the counter electromotive force of the motor, the speed and the position of the rotor through the estimated axis (δ, γ) for estimating the magnetic axis of the rotor, Calculate the delta current estimation error Δi _δ and the gamma current estimation error Δi _γ , calculate the estimated value of the back EMF of the motor through the delta current estimation error, calculate the speed estimate of the rotor, and estimate the gamma current Computing a correction value through the error, and then adding the correction value to the speed estimate value to calculate the speed correction estimate, and by integrating the speed correction estimate to calculate the position of the rotor.

According to the present invention, by using a low pass filter and an integral regulator when estimating back EMF, noise and estimation errors can be greatly reduced, and the position error of the rotor can be accurately sensed to implement a highly efficient motor, and the parameters of the motor. Accurate rotor speed and position estimation can be made even with changes.

By correcting the speed estimates, rotor speed and position can be estimated more efficiently when the motor parameters change.

In addition, it is possible to minimize rotor position and speed estimation errors that may occur in transient and steady state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a control block diagram of a permanent magnet synchronous motor according to an exemplary embodiment of the present invention, wherein a proportional integral regulator 21, a multiplier 22, a first low pass filter 23, a signal function 24, and a delay function are shown. (25), the integrator 26, the integral regulator 27, the second low pass filter 28 and the motor model 29.

Proportional integral regulator 21 uses integral control in parallel to proportional control to generate a control signal by integrating the gamma current error signal, reducing the steady-state error and speeding up the slow response of the system caused by transient response. have.

The multiplier 22 receives the correction value from the proportional integrator 21, receives the speed estimate from the integrator 27, calculates the speed correction estimate by applying the correction value to the speed estimate, and then calculates the first low pass filter. To send.

The first low pass filter 23 filters and is included in the high frequency of the speed estimation value transmitted from the multiplier 22 and transmits the same to the model motor 29.

The signal function 24 sets the speed signal corrected according to the signal of the estimated speed using the delta current error.

The delay function 25 delays the signal of the velocity estimation value transmitted from the integral regulator and transmits the signal to the signal function 24.

The integrator 26 estimates the position of the rotor after integrating the speed estimate when the speed correction estimate is transmitted. The integrator then reduces the steady state error.

When the delta current error signal Δi _δ is input, the integral regulator 27 calculates an estimated value of the back EMF of the motor using the input delta current error and then burns it to the second low pass filter.

The second low pass filter 28 filters the high frequency included in the back EMF estimate transmitted from the integration regulator 27 and transmits the filtered high frequency to the model motor 29.

At this time, the speed estimate is calculated using the back EMF estimate passed through the second low pass filter 28 and then transmitted to the multiplier 22.

The motor model 29 receives the back EMF estimate from the second low pass filter 28, receives the speed correction estimate from the first low pass filter 23, receives the current delta current and the gamma current, and then performs the next step. After estimating the gamma current and the delta current of the motor, the estimated gamma current i _γ ^{n + 1} is transmitted to the proportional integral regulator 21, and the estimated delta current Δ _δ ^{n + 1} is transmitted to the integral regulator 27 To send).

3 is a graph of an algorithm response to counter electromotive force that decreases by 1.5 times according to an embodiment of the present invention.

That is, (a) shows the change of the position of the rotor with time, it can be seen that the position of the rotor is constant with time, (b) shows the speed of the rotor with time, the You can see that the speed is constant.

4 is a flowchart illustrating a method of controlling a permanent magnet synchronous motor according to an exemplary embodiment of the present invention. Referring to FIG. 2, a method of controlling the motor will be described.

First, the delta current estimation error Δi _δ is calculated by comparing the delta estimation current i _δ ^{n + 1} of the next step calculated in the model motor 29 with the current delta measurement current i _δ ⁿ , A gamma current estimation error Δi _γ is calculated by comparing the gamma estimation current i _γ ^{n + 1} of the next step calculated by the motor 29 with the current gamma measurement current i _γ ⁿ .

Next, the estimated value of the back-emf of the motor is calculated (S2) and transmitted to the model motor 29 and the multiplier 22 through the delta current estimation error Δi _δ . Compute (S3) the speed estimate of.

That is, the delta current estimation error Δi _δ is transmitted to the integral regulator 27, and the estimated value of the counter electromotive force E of the motor is calculated through the integral regulator 27.

Here, the integral regulator 27 serves to reduce the influence of the sudden change in the delta current estimation error Δi _δ applied to calculate the counter electromotive force estimate.

The back EMF estimate E integrated in the next integral regulator 27 is transmitted to the second low pass filter 28, and the back EMF value passed through the second low pass filter 28 is estimated as the high frequency is filtered. To increase the smoothness.

At this time, the back EMF estimate is divided by the motor back EMF constant Ke, so that the rotor speed estimate is calculated (ω ₀ ).

Next, the rotor position is calculated by estimating the speed value of the rotor and integrating the speed estimate.

Next, if the parameters of the model motor and the actual motor parameters are different according to the parameters of the motor, an error that is not compensated for is generated and a speed correction value is calculated and applied to prevent such an error.

That is, the correction value of the speed is calculated through the gamma current estimation error Δi _γ (S4).

Here, the gamma current estimation error Δi _γ is transmitted to the proportional integral regulator 21 and then integrated to calculate a correction value. The calculated speed correction value is transmitted to the multiplier 22, and the transmitted correction value is applied to the speed estimation value. It is applied (S5) to correct the error of the speed estimate, and transmits the speed correction estimate (ω _cor ) to the motel motor 29 and the integrator 26.

In this case, the speed correction estimate is transmitted to the first low pass filter 23, and the speed correction estimate transmitted to the first low pass filter 23 is transmitted to the integrator 26, and the speed correction estimate is transmitted to the integrator 26. Is integrated and the position of the rotor is calculated (S6).

Here, the proportional integral regulator 21 has a small time constant and operates faster than the integral regulator 27. Therefore, when the rotor speed is steady state, the current estimation error is small and slow, and the integrating regulator 27 reduces the influence by the estimation parameter.

In addition, when the rotor speed is in the transient state, the integrating regulator 27 causes a large phase delay and is compensated by the fast proportional integrating regulator 21.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

As described in detail above, the present invention can significantly reduce noise and estimation error by using a low pass filter and an integration regulator when estimating back EMF.

In addition, it is possible to accurately detect the position error of the rotor to realize a high-efficiency motor, and to accurately estimate the rotor speed and position even when the motor parameters change.

By correcting the speed estimates, rotor speed and position can be estimated more efficiently when the motor parameters change.

In addition, it is possible to minimize rotor position and speed estimation errors that may occur in transient and steady state.

Claims (7)

In the method for estimating the counter electromotive force of the motor, the speed and the position of the rotor through the estimated axis (δ, γ) for estimating the magnetic axis of the rotor, Calculate a delta current estimation error Δi _δ and a gamma current estimation error Δi _{γ of} the estimated axis, After calculating the estimated value of the back electromotive force of the motor through the delta current estimation error, calculates the speed estimate of the rotor,  After calculating a correction value through the gamma current estimation error, the correction value is added to the speed estimation value to calculate a speed correction estimate value, And calculating the position of the rotor by integrating the speed correction estimate with respect to time. The method of claim 1, And the gamma current estimation error is integrated in a proportional integral regulator to reduce the steady state error. The method of claim 1, And the delta current estimation error is integrated in an integration regulator to reduce the steady state error. The method of claim 1, And the speed correction estimated value filters high frequency frequencies through a first low pass filter. The method of claim 1, The counter electromotive force estimation value is a control method of a permanent magnet type synchronous motor, characterized in that for filtering the high frequency through a second low pass filter. The method of claim 1, And the speed correction estimate is integrated in an integrator. The method of claim 1, wherein the calculating of the delta current estimation error and the gamma current estimation error comprises: Compute the delta current estimation error by comparing the delta estimated current of the next step calculated in the model motor with the current delta measurement current, and calculate the gamma current estimation error by comparing the gamma estimated current calculated in the model motor with the current gamma measurement current. Control method of a permanent magnet synchronous motor, characterized in that.

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