KR100561733B1 - A sensorless control method of permanent magnet synchronous motor using an instantaneous reactive power - Google Patents

Abstract

A sensorless control method of a permanent magnet synchronous motor using instantaneous reactive power is disclosed. According to the present invention, a) an initial input value including a stator resistance (Rs), a stator inductance (Ls), a back EMF constant (K _E ), and a line current (is) and a voltage (Vs) input to the synchronous motor. Receiving a step; b) calculating an estimated current equation based on the initial input value and the voltage equation of the synchronous motor; c) calculating an estimated speed equation including a compensation value C based on the initial input value and the voltage equation of the synchronous motor; d) calculating the actual reactive power by the cross product of the line current is and the estimated counter electromotive force Es, and the estimated reactive power by the cross vector of the estimated current i's and the estimated counter electromotive force Es; e) setting a compensation value C assuming that an error range between the actual reactive power and the estimated reactive power reaches '0'; f) repeating the above steps to set the compensation value C and the estimated current (i's), calculating instantaneous reactive power from the stator coordinate system, and calculating the estimated speed from the voltage equation of the synchronous motor. The effect can be prevented from occurring mechanism errors.

Permanent magnet, synchronous motor, stator coordinate system, sensorless, reactive power, estimated reactive power

Description

Sensorless control method of permanent magnet synchronous motor using instantaneous reactive power {A SENSORLESS CONTROL METHOD OF PERMANENT MAGNET SYNCHRONOUS MOTOR USING AN INSTANTANEOUS REACTIVE POWER}

1 is a block diagram illustrating a mathematical model of a synchronous motor.

Figure 2 is a block diagram for explaining the main arithmetic function of the DSP according to the present invention.

3 is a flowchart for explaining the main operation of the present invention.

4 is a coordinate system for explaining the error between the line current and the estimated current according to the present invention.

5 is a configuration diagram for explaining sensorless control of a synchronous motor according to the present invention.

6a and 6b are graphs showing experimental conditions of the present invention.

<Description of Symbols for Main Drawings>

201: current observer 203: speed estimation calculator

205: actual reactive power calculator 207: estimated reactive power calculator

209: speed error compensation unit 401: sensorless control device

403: DSP 417: DC link unit

419: three-phase inverter 421: synchronous motor

The present invention relates to sensorless control of a synchronous motor, and more particularly, a permanent magnet using instantaneous reactive power to secure driving stability of a synchronous motor by calculating an estimated speed using an instantaneous reactive power error of the synchronous motor. A sensorless control method for a synchronous motor.

In general, the use of an AC motor instead of a DC motor is increasing as a servo driving motor for driving an industrial device requiring high precision speed response control. The DC motor for servo operation can independently control the armature current, which has the advantage of easy torque control and speed control of the motor. However, the servo system using a DC motor requires maintenance and repair due to mechanical wear of the brush and the commutator, and has disadvantages such as high speed and high pressure due to the commutation limit of the commutator.

Surface-Mounted Permanent Magnet Synchronous Motor has high reliability because there is no heat generated by rotor copper loss, and only heat generated by iron loss of fixed armature core and copper winding of armature winding exists. In addition, it has the advantage of higher torque ratio and efficiency than other motors. However, since the permanent magnet synchronous motor receives the magnetic flux from the permanent magnet attached to the rotor, it is necessary to always know the exact position of the rotor in order to control it. Therefore, resolver, absolute encoder, and hole An electronic position detector using a magnetic sensor such as an element is essential. However, these position detectors are not only expensive in general, but also have a disadvantage in that separate complicated hardware must be configured in the controller.

In addition, the sensor used in the position detector is limited to use because it is greatly affected by the surrounding environment, such as vibration and humidity, and because the sensor must be mounted on the motor shaft, such as increase in size of the motor and deterioration of processability The problem is caused.

The present invention was created to solve the above problems, and an object of the present invention is to use the voltage equation and instantaneous reactive power of the motor to estimate the speed of the motor. The present invention provides a sensorless control method of a permanent magnet synchronous motor using instantaneous reactive power capable of driving.

Sensorless control method of a permanent magnet synchronous motor using instantaneous reactive power according to the present invention for achieving the above object, in the sensorless control method of a synchronous motor, a) stator resistance (R _S ) of the synchronous motor Receiving an initial input value including a stator inductance L _S , a counter electromotive force constant K _E , and a line current i _S and a voltage V _S input to the synchronous motor;

b) calculating an estimated current of the synchronous motor based on the initial input value and the voltage equation of the synchronous motor;

c) calculating an estimated rotor speed of the synchronous motor including a compensation value C based on the initial input value and the voltage equation of the synchronous motor;

d) the actual reactive power by the cross product of the line current (i _S ) and the estimated back electromotive force (E _S ) and the estimated current (i ' _S ) by the estimated current equation and the cross product of the estimated back electromotive force (E _S ) Calculating an estimated reactive power by

e) calculating an error between the actual reactive power and the estimated reactive power, and setting the compensation value C such that the calculated error is modified to '0';

f) setting the estimated current i ' _S based on the compensation value C, and feeding back to step c) so that an error between the actual reactive power and the estimated reactive power becomes'0' and repeating the process. Doing;

g) determining an estimated speed and an estimated position of the synchronous motor based on the compensation value C and the estimated current i ' _S when the error between the actual reactive power and the estimated reactive power becomes'0'.; And

h) controlling the synchronous motor by using the estimated speed and the estimated position.

Preferred embodiments of the present invention having such features will be described in detail with reference to the accompanying drawings. 1 is a block diagram showing a mathematical model of a synchronous motor for explaining the present invention.

As shown, the synchronous motor is a three-phase cylindrical permanent magnet synchronous motor, showing resistance and coil as a mathematical model for the winding coil of the stator. The resistance Rs represents the winding resistance of the winding coil, and the coil Ls represents the inductance of the coil. The present invention will perform the speed and position estimation of the synchronous motor from the coordinates of this stator center.

2 is a block diagram illustrating a speed and position estimation using instantaneous reactive power of a synchronous motor. The illustrated current observer 201 receives the actual current value of each phase (Phase: two phases of X, Y, Z-the other one is calculated from two phases) from a three-phase input power source. The D-axis (D-AXIS) current and the Q-axis (Q-AXIS) current are calculated. The speed estimating calculation unit 203 estimates the arithmetic driving speed of the synchronous motor based on the currently supplied D-axis (D-AXIS) current / voltage and the Q-axis (Q-AXIS) current / voltage.

The actual reactive power calculating unit 205 and the estimated reactive power calculating unit 207 are estimated from the measured actual current and the current observing unit 201 and calculate the actual reactive power and the estimated reactive current using the estimated current. The speed error compensator 209 calculates a reactive power error based on the result values of the actual reactive power calculating unit 205 and the estimated reactive power calculating unit 207, and speeds up the reactive power error to be '0'. Determine the compensation for the error. Speed error compensation feeds back to the speed estimation calculator 203 to correct the speed estimation value, and performs correction of the current observing unit 201 corresponding to the speed estimation value correction.

The correction value of the current observer 201 is fed back to the estimated reactive power calculator 207 to compensate for the speed error again, thereby continuously reducing the estimated speed error.

Hereinafter, a mathematical calculation method for each module will be described with reference to FIG. 3.

First, the process proceeds to step S301 to set the initial parameter value of the synchronous motor and the initial value for the mathematical model. The initial parameters are stator resistance (R _S ), stator inductance (L _S ), back EMF constant (K _E ), etc., which are parameters provided in the manufacture of the initial synchronous motor. In addition, the initial value of the mathematical model is set to '0' as the initial value for the correction value C to be described below.

In step S303, the current observer 201 calculates the D-axis and Q-axis currents and voltages based on the stator coordinate system based on the actual amount of current (is) and voltage (Vs) input to the synchronous motor. Equation 1 may be used.

(V _SD : voltage applied to the D axis of the stator coordinate system, V _SQ : voltage applied to the Q axis of the stator coordinate system, R _S : stator resistance, L _S : stator inductance, i _SD : D axis current, i _SQ : Q-axis current, E _SD : D-axis counter electromotive force, E _SQ : Q-axis counter electromotive force)

The voltage V _SD applied to the D-axis of the stator coordinate system and the voltage V _SQ applied to the Q-axis of the stator coordinate system have respective D-axis counter electromotive force (E _SD ) and Q-axis counter electromotive force (E _SQ ). When the current change amount is calculated from 1, it is shown in Equation 2.

로 표현된다. 여기서 Blank( °또는 ^.)는 미분자를 의미하며, K_E는 역기전력 상수이며, 상기 ω_r은 회전자의 각속도이고, θ_r은 회전자의 회전 각도이다. 이로부터 S305 단계를 통해 D축 및 Q축의 추정 전류량를 산출하면 수학식 3과 같이 표현된다.

It is expressed as Here, Blank (° or ^. ) Means a fine molecule, K _E is a counter electromotive force constant, ω _r is the angular velocity of the rotor, θ _r is the rotation angle of the rotor. When the estimated current amounts of the D-axis and the Q-axis are calculated from the step S305, Equation 3 is expressed.

The above equation shows the amount of current change supplied to the synchronous motor, and the current observation unit 201 performs the arithmetic based on the equation (3). This arithmetic does not take into account the error of the supply current amount. Meanwhile, the speed estimation calculator 203 calculates (estimates) the rotational speed of the synchronous motor based on the angular velocity ω _r described in Equation 3, that is, the detection result of the uncorrected current observing unit 201. do. Through step S307, the angular velocity ω _r is calculated by multiplying -sinθ _r and cosθ _r using the D-axis estimated current equation and the Q-axis estimated current equation of Equation 3, respectively.

delete

And p is a differential operator.

The arithmetic equation described in Equation 4 represents the rotor speed of the synchronous motor, and after correcting the correction value C in the above equation in consideration of an error occurring when measuring the parameter of the motor or detecting the line current and the input voltage, Set this to the estimated speed ω _r '. Therefore, the estimated speed ω _r 'of the motor is expressed by Equation 5.

Ω _r 'in Equation 5 is an estimated angular velocity, and θ _r is an estimated position or rotation angle. As described above, in order to calculate the speed estimating value through the speed estimating calculating unit 203, the correction value C should be calculated, which may be achieved through the speed error compensating unit 209. Therefore, the correction value C by the speed error compensator 209 is calculated based on the result values calculated by the actual reactive power calculator 205 and the estimated reactive power calculator 207.

First, through step S309, the reactive power q _m is obtained from the counter electromotive force E _s and the line current i _s .

here,

(E ' _S is an estimated back electromotive force, and the use of the estimated back electromotive force for the actual reactive power q _m is for extracting an equation for an estimated speed included in the estimated back electromotive force.)

If the estimated current i _s ′ with respect to the reactive power q _m is out of the actual current i _s value by Δθ _r , the phase of the estimated reactive power q _m ′ at this time is the reactive power q _m. Is rotated by Δθ _r relative to). Based on this, the estimated reactive power can be calculated in step S311. That is, as shown in FIG. 4, the estimated current i _s ′ is rotated by Δθ _r more than the actual current i _s value, and the estimated reactive power q _m ′ is expressed by Equation 7 below.

As described above, the reactive power q _m and the estimated reactive power q _m ′ calculated by the actual reactive power calculator 205 and the estimated reactive power calculator 207 have an error of Δθ _r . The speed error compensator 209 applies an approximation to Equation 7 to calculate an error between the reactive power q _m and the estimated reactive power q _m ′. That is, it is assumed that the angular velocity ω _r is not '0', and the estimated reactive power is extracted when the Δθ _r value is approached to '0'. This is shown in Equation 8.

일 경우, S313 단계에서 무효전력의 오차는,

이다.
이때, 하기의 조건식,here

If, in step S313 the error of reactive power,

to be.
At this time, the following conditional expression,

delete

을 만족하는 비례 이득 Kcp를 결정하고, S315 단계를 거쳐, 안정적 보상이 이루어지도록 적분이득을 부가하여 수학식 9와 같이 상기 보상값 C를 결정한다. 즉, 상기 조건식을 이용하여 Kcp를 판별하고 특별한 절대치의 기준이 아니라 안정성을 만족하는 범위내에서 안정적인 보상이 이루어지도록 적분 이득을 부가형 C를 결정한다.

To determine the proportional gain Kcp to satisfy, and through the S315 step, the integral gain is added to ensure a stable compensation to determine the compensation value C as shown in Equation (9). That is, Kcp is determined using the conditional expression, and the integrated gain additional C is determined so that stable compensation is achieved within a range that satisfies stability rather than a specific absolute value criterion.

(Kci / p is integral gain and p is a differential operator.) The speed error compensator 209 calculates the compensation value C, and then compensates the compensation value C with the speed estimation calculator 203. The speed estimation calculator 203 calculates an estimated speed of the synchronous motor according to Equation 5 based on the compensation value C. The speed estimation calculator 203 provides the estimated speed ω _r ′ information to the current observer 201, the actual reactive power calculator 205, and the estimated reactive power calculator 207.

In S317, the current observing unit 201 substitutes the calculated estimated speed ω _r ′ into the voltage equation of Equation 3, and then obtains an estimated current of the synchronous motor by Equation 10.

Here, the error equations (e _SD and e _SQ ) are extracted through the estimated currents (i ' _SD , i' _SQ ) and the voltage equation of Equation (3).

여기서, Blank( °)는 미분자이다.

Here, Blank (°) is the fine molecule.

를 만족하도록 k₁, k₂를 설정한다. 상기에서 특정한 k₁, k₂를 선택하는 것이 아니라 극배치 기법에 의하여 안정성을 확보하는 범위 내에서 선택하도록 하는 것이 바람직하다.
상기 k₁e_SD 및 k₂e_SQ는 추정전류와 실제 전류의 감산으로 인해 오차를 보정하기 위한 상수이다. 여기서 상기 수학식 8의 조건에 따라 △θ_r을 '0'에 근접시킬 경우, S319 단계에서 실제 무효전력과 추정 무효전력의 오차가 '0'에 근접하도록 상기 과정을 반복하는 것으로, 결국 상기 수학식 11의 파라메타는, In addition, to ensure the stability in the equation (11)

Set k ₁ and k ₂ to satisfy. Rather than selecting specific k ₁ and k ₂ above, it is preferable to select within the range to ensure stability by the pole placement technique.
K ₁ e _SD and k ₂ e _SQ are constants for correcting errors due to subtraction of the estimated current and the actual current. In this case, when Δθ _r approaches '0' according to the condition of Equation 8, the process is repeated so that an error between the actual reactive power and the estimated reactive power approaches '0' in step S319. The parameter of formula 11 is

및

가 '0'으로 수렴하며, 상기의 오차방정식은 수학식 12로 표현된다.

And

Is converged to '0', and the error equation is represented by Equation 12.

At this time, the estimated current and the actual current which corresponds to the k1, k2 is a compensating value C of to be set to a value, which is estimated velocity (ω _'r) to stabilize so as to converge the error equation to zero and It is a constant value for the error of. The estimated speed ω ' _r and the estimated current value determined in this way can be controlled to be equal to the actual speed ω _r and the actual current value, and a control pattern for reaching the set speed value of the synchronous motor If required, the set speed and current values can be reached by repeating the above process.

The control system of the present invention will be described as an example based on the above calculation formula.

5 is a block diagram showing a system for sensorless control of a synchronous motor according to the present invention. As shown, the three-phase power source is supplied to the three-phase inverter 519 through the three-phase rectifier 515 and the DC link unit 517, the stable DC (DC) power, the three-phase inverter 519 It is connected to the synchronous motor 521 (PMSM). The sensorless control device 501 detects reactive power from the DC link unit 517 and detects a current amount from a part (minimum two phases) of three-phase power input to the synchronous motor 521.

The sensorless controller 501 detects a voltage from the DC link unit 517, detects an input current of the synchronous motor 521, and converts it into a digital signal, corresponding to an AD converter 511 and an input signal. The DSP 503 generates a control signal for controlling the input power of the synchronous motor 521 according to the input result, and supplies the driving signal and the current amount of the three-phase inverter 519 in response to the control signal. And a gate driver 507 for driving the three-phase inverter 519 in response to an output signal of the gate controller 505 and the gate controller 505.

The non-described synchronous motor load device 523 (Dynamometer), the synchronous motor load device controller 525 (Dynamometer Controller) and the oscilloscope 527 is an experimental device for testing the sensorless control device 501.

The DC link unit 517 is connected in parallel with the input power line of the three-phase inverter 519, and used an electrolytic capacitor of 450V, 4700 kW, and the DSP 503 sets the output voltage of the DC link unit 517 to 160. 입력 It is being input in units. The three-phase inverter 519 uses an IGBT module and uses a power circuit of a three-phase VSI. The synchronous motor 521 is an 8-pole motor having a rated capacity of 1.8 kW, a rated torque of 5.88 N · m, and a rated speed of 3000 rpm, a stator resistance of 0.22 Ω, a stator inductance of 0.88 mH, and a counter electromotive force constant of 0.0522 V. / r / min, and the coefficient of inertia is 18.6 × 10 ^-4 kg m 2.

The AD converter 511 receives an actual amount of current supplied to the synchronous motor 521 and provides the digitized signal to a digital signal processor (503). The DSP 503 may include information such as stator resistance (R _s ), inductance (L _s ), back EMF constant (K _E ), and detection voltage (V _S ) of the DC link unit 517 of the synchronous motor. The actual speed and the estimated speed are calculated based on 4 and (5). Here, the estimated speed has a compensation value C, and the DSP 503 calculates an actual reactive power and an estimated reactive power based on Equations 6 and 7 to calculate the compensation value C. Calculate the error of.

The error of the reactive power is based on Equation 8, and a compensation value C proportional to the phase difference between the actual reactive power and the estimated reactive power is calculated as Equation 9. The compensation value C is a compensation for the estimated speed. When the estimated speed information including the compensation value C is shown to the oscilloscope 527 through the DA converter 509, the estimated speed of (b) is calculated as shown in FIG. 6A. (a) shows the speed change from 50rpm to -50rpm as the actual speed. Therefore, it can be seen that the estimated speed change through the compensation value C of the DS 503 is shown to be the same as the actual speed change.

In addition, the DSP 503 receives the actual current value by the line current, and based on the stator information (resistance, inductance), back EMF constant and the actual voltage input value of the DC link unit 517 according to equation (10) The estimated current is calculated, and the difference between the actual current and the estimated current is calculated from Equation 11. The error equation calculated as described above has constant values k ₁ and k ₂ , and the estimated values k ₁ and k ₂ are calculated from Equation 12 to infer the estimated current value i ' _S.

The estimated current value i ' _S may calculate an estimated reactive power defined by the cross product of line current and counter electromotive force according to Equation 6, and as shown in FIG. 6B as an experimental basis for the calculation result, the actual reactive power (a ) Represents an estimated reactive power (b) for.

Therefore, the estimated power and the estimated speed according to a predetermined arithmetic expression are calculated in response to the change of the current / voltage according to the change of the current / voltage input to the synchronous motor of the DSP 503 or the change of the external force pressed by the synchronous motor. Accordingly, the sensor can control the unsynchronized synchronous motor. The DSP 503 provides the current and voltage corresponding to the estimated current and the estimated speed to the gate controller 505, and the gate controller 505 passes the current to the three-phase inverter 519 through the gate driver 507. By supplying / voltage, it performs speed control, torque control, rotation angle control, etc. of the synchronous motor as required.

In addition, the control of the synchronous motor can input the control conditions of the synchronous motor, for example, the rotation speed, rotation position, torque, etc. to the input port of the DS 503 to perform the motor control according to external conditions Can be.

What has been described above is just one embodiment showing the sensorless control method of the permanent magnet synchronous motor using instantaneous reactive power according to the present invention, the present invention is not limited to the above-described embodiment, in the following claims As claimed, any person having ordinary skill in the art without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

The sensorless control method of the permanent magnet synchronous motor using instantaneous reactive power described in the present invention has an effect of lowering the production cost of the synchronous motor as a sensor for detecting the position of the permanent magnet synchronous motor is unnecessary, and from the stator coordinate system. The instantaneous reactive power is calculated, and the estimated speed is calculated from the voltage equation of the synchronous motor, thereby obtaining the effect of preventing mechanism errors occurring in the mechanical equations of the motor.

Claims (3)

In the sensorless control method of a synchronous motor, a) Initial input including stator resistance (R _S ), stator inductance (L _S ), back EMF constant (K _E ) of the synchronous motor, and line current (i _S ) and voltage (V _S ) input to the synchronous motor. Receiving a value; b) calculating an estimated current of the synchronous motor based on the initial input value and the voltage equation of the synchronous motor; c) calculating an estimated rotor speed of the synchronous motor including a compensation value C based on the initial input value and the voltage equation of the synchronous motor; d) the actual reactive power by the cross product of the line current (i _S ) and the estimated back electromotive force (E _S ) and the estimated current (i ' _S ) by the estimated current equation and the cross product of the estimated back electromotive force (E _S ) Calculating an estimated reactive power by e) determining the compensation value C based on the error between the actual reactive power and the estimated reactive power; f) setting the estimated current i ' _S based on the compensation value C, and feeding back to step c) so that an error between the actual reactive power and the estimated reactive power becomes'0' and repeating the process. Doing; And g) a permanent magnet using instantaneous reactive power, characterized in that the control of the synchronous motor is performed using the estimated speed when the error between the actual reactive power and the estimated reactive power becomes '0' as the actual speed. Sensorless Control Method of Synchronous Motor. The method of claim 1, wherein the compensation value C is represented by the following equation;

Where, the Kcp is proportional gain, the Kci is integral gain, p is the differential operator, Δq _m is the difference between the actual reactive power and the estimated reactive power, the permanent magnet synchronization using instantaneous reactive power Sensorless control method of motor. The method of claim 2, wherein the proportional gain Kcp is a condition,

Sensorless control method of a permanent magnet synchronous motor using instantaneous reactive power, characterized in that to determine to satisfy.

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