KR100668973B1 - Method for estimating velocity/position of motor - Google Patents

Abstract

The present invention provides a method for estimating the position / speed of a motor having a rotor, the method comprising: calculating a position error of the rotor; Estimating the rotational speed of the rotor by proportionally integrating the calculated position error and mixing the proportionally integrated position error and a predetermined command torque based on the mechanical equation of the motor. Accordingly, the present invention provides a method for estimating the position / speed of a motor capable of robust sensorless vector control by minimizing the influence of noise and estimating a precise rotor speed.

Description

METHOD FOR ESTIMATING VELOCITY / POSITION OF MOTOR}

1 and 2 are control block diagrams for estimating counter electromotive force and estimating the position and speed of a rotor in a conventional motor control apparatus.

3 is a control block diagram of a motor control apparatus according to the present invention,

4 is a diagram illustrating an example of the position / speed estimator of FIG. 3;

5 is a diagram illustrating an example of the PID controller and the position / speed observer of FIG. 4.

* Explanation of symbols for main parts of the drawings

1: motor controller 10: speed controller

11 current controller 12 vector controller

13 Inverter 14 Current Detector

15: motor 20: position / error estimation unit

21: back EMF estimation unit 22: position error calculation unit

23: PID control unit 24: position / error observer

The present invention relates to a method for estimating the speed / position of a motor. More particularly, the present invention relates to a method for estimating precise rotor position, speed, and / or torque in sensorless vector control. It relates to a speed / position estimation method.

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.

In the conventional motor using the sensorless vector control, US Patent No. 6,081,093 discloses a sensorless control of an embedded permanent magnet synchronous motor (IPMSM) capable of continuously controlling speed in a full speed range. Disclosed are methods and apparatus

The control method disclosed in the U.S. Patent No. sets the coordinate dq axis rotating at the actual motor rotational speed ω _R and the estimated rotor axis γ-δ axis of the motor, and as shown in FIG. When determining the rotational speed ω _{R γ} on the δ axis, prepare a distribution gain K2 that is set to increase as the absolute value of the rotational speed command ω _RREF increases, and set K1 to the rotational speed command ω _RREF , or the counter electromotive force of the synchronous motor. The rotation speed ω _{R γ} of the estimated rotor axis γ-δ axis is determined by adding the product of multiplying K2 by the speed estimate ω _RP obtained from the counter electromotive force estimate.

Meanwhile, a paper published by the inventor of the present invention, "Sensorless control of interior permanent-magnet machine drives with zero-phase lag position estimation". Industry Applications, IEEE Transaction on, Volume: 39, Issue: 6, Nov.-Dec. 2003] discloses an algorithm for estimating saliency-based EMF with rotor position information. 1 and 2 are block diagrams illustrating a Saliency-based EMF and a position / speed estimation of the embedded permanent magnet motor disclosed in the paper.

Here, the rotor position error is calculated by the cross-product of the estimated saliency-based EMF and the unit vector. The rotor position and speed are estimated using the calculated rotor position error, proportional integral derivative (PID) controller, and motor mechanical equation.

The speed of the rotor is generally calculated by differentiating the rotor position error ε in the differential controller and the product of the speed error and the derivative gain bo is added to the output of the proportional integral controller Ko + Kio / s and estimated through inertia terms and integrators. When the above process is implemented in the discrete format, the position error is differentiated and integrated again, so unnecessary calculation error occurs. In Fig. 2, the rotor position error ε is directly multiplied by the differential controller gain / estimated inertia Bo / ^ j to eliminate unnecessary differential calculations and summed at the front end of the position calculation integrator, which is the estimated velocity value. .

However, in the sensorless control method disclosed in the U.S. Patent, K (i (k) -i _est (k)) of different axes are used for estimating counter electromotive force of the estimated rotor axis γ-δ axis and act as disturbance of the observer. Back EMF estimation error occurs. If the rotor position and speed are estimated based on the estimated back EMF due to the back EMF estimation error, an error may occur. When the estimated speed is fed back and the vector control is performed to the estimated position and the estimated position, the estimated error decreases the speed control performance, decreases the efficiency, and causes noise and vibration.

In addition, even in the method disclosed in the above paper, there is a differential calculation term ε × bo / ^ J with noise in estimating speed, and the estimated speed includes noise. The estimated speed including the noise may cause pulsation due to the pulsation during the speed control of the sensorless vector control.

Accordingly, an object of the present invention is to provide a method for estimating the position / speed of a motor capable of robust sensorless vector control by estimating the precise position, speed, and torque of a rotor in sensorless vector control of a motor.

According to the present invention, there is provided a method for estimating a position / speed of a motor having a rotor, the method comprising: calculating a position error of the rotor; And proportionally integrating the calculated position error and estimating the rotational speed of the rotor by mixing the proportionally integrated position error and a predetermined command torque based on the mechanical equation of the motor. Is achieved by the position / speed estimation method of.

The method may further include estimating the rotational position of the rotor by mixing the calculated position error with the proportional differential integral and mixing the proportional differential position error with the command torque based on the mechanical equation of the motor. Can be.

The estimating of the rotational speed of the motor may further include removing high frequency characteristics from the estimated rotational speed.

Estimating torque of the rotor by proportionally integral control of the calculated position error; Generating a torque command for controlling the rotational speed of the rotor; Generating a corrected torque command by comparing the torque command with the estimated torque; And controlling the rotation speed of the rotor based on the correction torque command.

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

3 is a control block diagram of the motor control apparatus 1 according to the present invention. As shown in the figure, the motor controller 1 includes a motor, an inverter unit 13, a current detector 14, a position / speed estimator 20, a speed controller 10, a current controller 11, and a vector. Controller 12.

The motor according to the present invention may be either a surface-mounted permanent magnet synchronous motor (SPMSM) or an embedded permanent magnet synchronous motor (IPMSM). The motor is driven in accordance with the power source from the inverter unit 13.

The inverter unit 13 supplies a three-phase current required for driving the motor. Here, the inverter section 13 controls the three-phase current output based on the voltage command signals Va, Vb, and Vc from the vector controller 12, thereby varying the rotational speed of the motor.

The current detector 14 detects the current at each output terminal of the inverter unit 13 and transfers the detected current vector is to the position / speed estimation unit 20 based on the detected current at the output terminal of the inverter unit 13. Output

Here, the current detector 14 may have various configurations. For example, three-phase current can be directly detected by using a current transducer or a shunt resistor in series with each of the three phases of the motor. In addition, the current of two phases can be detected by two current transducers or series shunt resistors, and the current of the other one phase can be estimated by the detected current value of the two phases. In addition, the three-phase current may be estimated by reconfiguring the three-phase current with one series shunt resistor on the DC bus side or between the lower switches of the inverter unit 13 and ground in series.

The position / speed estimator 20 receives the detected current vector is from the current detector and a torque command and a voltage command vector to be described later, and estimates the position θ _r , the estimated speed ω _r , and the estimated load torque ( T _L ) is estimated and output. The calculation process of the estimated position θ _r , the estimated speed ω _r and the estimated load torque T _L by the position / speed estimating unit 20 according to the present invention will be described later.

On the other hand, the speed command ω _r ^* input by the user and the estimated speed ω _r estimated and output by the position / speed estimating unit 20 are compared and output by the first comparator.

And outputs to the speed controller 10 the speed command input from the first comparator (ω _r ^*) and the estimated speed (ω _r), the torque command (T _e ^*) to the current controller 11 on the basis of the comparison values . Here, the estimated load torque T _L output from the position / speed estimator 20 of the motor control apparatus 1 according to the present invention is a torque command _Te ^* from the speed controller 10 by the second comparator. ) Is added to the current controller 11.

The current controller 11 receives the torque command _Te ^* from the speed controller 10 and outputs a voltage vector command V ^* . Here, the current controller 11 may receive the estimated current value calculated in the process of estimating the counter electromotive force from the position / speed estimator 20 and reflect it in the generation of the voltage vector command V ^* .

The vector controller 12 receives the voltage vector command V ^* output from the current controller 11 and the estimated position θr output from the position / speed estimator 20 and based on the two input values. The voltage command signals Va ^* , Vb ^* , Vc ^* for each phase of the inverter section 13 are output.

Hereinafter, the position / speed estimator 20 of the motor control apparatus 1 according to the present invention will be described in detail with reference to FIGS. 4 and 5.

As shown in FIG. 4, the position / speed estimator 20 according to the present invention includes a counter electromotive force estimator 21, a position error calculator 22, a PID controller 23, and a position / speed observer 24. It may include.

The counter electromotive force estimator 21 receives the detection current vector is output from the current detector and the voltage vector command V ^* output from the current controller 11 to estimate the counter electromotive force through a predetermined estimation process. Here, various estimation methods known in the art may be used as the estimation method of the counter electromotive force. For example, a method for estimating back EMF disclosed in US Pat. No. 6,081,093, or the paper "Sensorless control of interior permanent-magnet machine drives with zero-phase lag position estimation" published by the inventor of the present invention. Industry Applications, IEEE Transaction on, Volume: 39, Issue: 6, Nov.-Dec. Any of the back electromotive force estimation methods disclosed in 2003 'may be used, and other estimation methods may be used.

The position error calculator 22 receives the counter electromotive force estimated by the counter electromotive force estimator 21 and calculates a position error θ _er . Here, the position error calculation unit 22 may calculate the position error θ _er of the rotor using an arc tan trigonometric function, and other calculation methods may be used.

The position error θ _er outputted from the position error calculation unit 22 is estimated position θ _r , estimated speed ω _r , and estimated load through the PID controller 23 and the position / speed observer 24. Output is torque (T _L ).

5 is a diagram illustrating in detail the PID controller 23 and the position / speed observer 24 of the position / speed estimator 20 according to the present invention.

Here, the position / speed estimator 20 according to the present invention estimates the rotational speed of the rotor by proportionally integral control of the position error θ _er of the rotor calculated based on the estimated back EMF, and thus estimates the estimated speed (ω). _r ) Here, the position / speed estimator 20 proportionally integrates the position error and mixes the command torque _Te ^* based on the mechanical equation of the motor to estimate the rotational speed of the rotor.

That is, as shown in FIG. 5, the position error [theta] er output from the position error calculating section 22 is added through the proportional calculation term 23b and the integral calculation term 23a, and the differential calculation term 23c. ) Is output at the front end of the summation so that the noise component of the differential calculation term 23c is not reflected in the estimated speed ω _r . Therefore, the vibration noise may be minimized by minimizing the fluctuation range in the speed control by reducing the error due to the noise when the motor speed is estimated.

Here, the estimated speed ω _r passes through the low pass filter (LPF: Low Pass Filter) 24b, thereby removing high frequency noise components, thereby enabling more accurate speed estimation. Here, the low pass filter 24b can be used selectively.

On the other hand, the estimated position θ _r estimated and output by the position / speed estimator 20 is estimated through the control of the differential derivative of the position error θ _er output from the position error calculator 22. That is, the position error θ _er output from the position error calculation unit 22 is summed through the proportional calculation term 23b and the integral calculation term 23a, and then the torque command output from the speed controller 10 ( T _e ^* ). And is output to the position error (θ _er) differential calculating section (23c) is made product value and summing the estimated position (θ _r) calculating an estimated position (θ _r) via an integrator (24a) for the after the.

The position / speed estimator 20 controls the position error θ _er in proportional integral to output the estimated load torque T _L. That is, the position error θ _er outputted from the position error calculation unit 22 is summed through the proportional calculation term 23b and the integral calculation term 23a and calculated as the estimated load torque T _L.

Herein, reference numerals 24c and 24d of FIG. 5 are terms reflecting the number of poles of the motor and compensate for the difference between the mechanical rotational speed and the electrical rotational speed.

In the above-described embodiment, an example of calculating the position error of the rotor by estimating counter electromotive force has been described. In addition, other methods for calculating the positional error of the rotor are described, for example, in Degner M.C., Lorenz R.D. "Position estimation in induction machines utilizing rotor bar slot harmonics and carrier- frequency signal injection" Industry Applications, IEEE Transaction on, Volume: 36, Issue: 3, May.- June. 2000 'can be calculated by the method of calculating the position error of the rotor using a high frequency disclosed in 2000'.

In this way, by calculating the position error of the rotor, and proportionally integrated the calculated position error, and by estimating the rotational speed of the rotor by mixing the proportional integral position error and a predetermined command torque based on the mechanical equation of the motor, By minimizing the influence of noise, robust sensorless vector control is possible by estimating the precise position, speed and torque of the rotor.

As described above, the present invention provides a method for estimating the position / speed of a motor capable of robust sensorless vector control by minimizing the influence of noise and estimating the precise position, speed, and torque of the rotor. .

Claims (4)

In the position / speed estimation method of a motor having a rotor, Calculating a position error of the rotor; Estimating the rotational speed of the rotor by proportionally integrating the calculated position error and mixing the proportionally integrated position error and a predetermined command torque based on the mechanical equation of the motor; Removing the high frequency characteristic from the estimated rotation speed. The method of claim 1, And proportionally differentially integrating the calculated position error, and estimating the rotational position of the rotor by mixing the proportionally differentiated position error and the command torque based on the mechanical equation of the motor. Motor position / speed estimation method. delete The method of claim 2, Estimating torque of the rotor by proportionally integrating the calculated position error; Generating a torque command for controlling the rotational speed of the rotor; Generating a corrected torque command by comparing the torque command with the estimated torque; And controlling the rotational speed of the rotor based on the correction torque command.

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