RU2455748C1 - Method for control of ac electronic motor and tracking system for its implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in the method for control of an AC electronic motor three-phase power-supply voltage is generated of the sign of difference between the signal of the three-phase sensor of the synchronous motor rotor position and the signal of the synchronous motor current three-phase sensor. The control signal is generated by way of subtracting the speed feedback signal and the angle feedback signal from the from the angle assignment signal. The tracking system with an AC electronic motor comprises a modulator, a three-phase sensor of the synchronous motor rotor position, a three-phase demodulator, a three-phase summator, a three-phase relay, a three-phase converter, a three-phase synchronous motor current sensor, a three-phase synchronous motor; additionally introduced are a reducer with an angle sensor and the synchronous motor speed sensor, a summator with one summation input and two countdown inputs output connected to the tracking system elements as per the invention formula.

EFFECT: provision of characteristics identical to those of a DC collector motor by means of analytical design of the AC electronic motor shaft turn controller, optimal in terms of accuracy.

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Description

The invention relates to controlled electric motors, in particular to the class of valve motors (brushless DC motors), and may find application instead of a DC brushless motor, for example, in servo systems of automatic control and regulation.

Known methods for controlling a valve motor based on the conversion of the angle of rotation of the shaft of a synchronous motor into a three-phase electric signal of the position sensor of the rotor of the motor, the amplitude of which is proportional to the control signal, and the formation of a three-phase voltage of the motor supply from it, the average value of which changes according to a sinusoidal law [V.A. Golovatsky et al. A control device for a brushless DC motor on power circuits. In the book. Electronic technology in automation. Collection of articles, ed. Yu.I. Koneva. Issue 4. M., 1973, pp. 34-37].

This control method allows you to eliminate these disadvantages, providing a smooth and wide control of the speed of the valve motor, small ripple torque and high efficiency. However, the static and dynamic characteristics of a valve motor with this control method are significantly different from the characteristics of a DC collector motor [V.N. Kryvoy et al. Contactless DC motors. Informelectro. M., 1970, pp. 5-8], which is a disadvantage of the known method.

Of the known methods of controlling a valve motor, the closest in technical essence is the method that is selected as a prototype for the proposed method. This method consists in the fact that when converting the angle of rotation of the shaft of the synchronous motor into a three-phase electric signal of the position sensor of the rotor of the synchronous motor, the amplitude of which is proportional to the control signal, and forming from it a three-phase supply voltage of the synchronous motor, the average value of which changes according to a sinusoidal law, a three-phase voltage synchronous motor power supply is formed from the sign of the difference signal of the three-phase rotor position sensor of the synchronous motor and the signal a three-phase synchronous motor current sensor [RF patent №2354036. Sukhinin B.V., Surkov V.V., Egorov A.Yu., Domnin A.N., Surkov A.V. The method of controlling a valve motor and a tracking system for its implementation].

This control method allows for smooth and wide control of the speed of the valve motor, small ripple torque and high efficiency. The static and dynamic characteristics of this control method are completely analogous to the static and dynamic characteristics of a DC collector motor. However, with this method of control, the angle of rotation of the shaft of the valve motor is worked out with this method of control is not optimal in accuracy.

Known schemes of valve motors containing a three-phase synchronous motor connected to the output of a three-phase converter, the average value of the output voltage of which varies according to a sinusoidal law, a three-phase position sensor of the rotor of a synchronous motor, the field winding of which is connected to the output of the modulator, control voltage is applied to the input of the modulator, the output is three-phase the rotor position sensor of the synchronous motor is connected to the input of a three-phase demodulator, and the output of a three-phase demodulator with of the connections to the input three-phase converter [V.A.Golovatsky et al. Control device brushless DC motor to power circuits. In the book. Electronic technology in automation. Collection of articles, ed. Yu.I. Koneva. Issue 4. M., 1973, pp. 34-37].

Such a valve motor eliminates these drawbacks and provides smooth and wide speed control, small ripple torque and high efficiency. However, its static and dynamic characteristics with such a well-known circuit are significantly different from the characteristics of a DC collector motor [V.N. Kryvoy et al. Contactless DC motors. Informelectro. M., 1970, pp. 5-8], which is a disadvantage of the known valve motor.

Of the known valve motors, the closest in technical essence is a valve motor, which is selected as a prototype for the inventive device. The tracking system contains a series-connected modulator, a three-phase rotor position sensor of a synchronous motor, a three-phase demodulator, a three-phase converter, a three-phase synchronous motor, the rotor of which is mechanically connected to the shaft of a three-phase rotor position sensor of a synchronous motor, a three-phase relay, a three-phase synchronous motor current sensor and a three-phase adder whose summing input is connected to the output of a three-phase demodulator, and the subtracting input is connected to the output of a three-phase sync current sensor engine, the output of the three-phase adder is connected to the input of the three-phase relay, the output of the three-phase relay is connected to the input of the three-phase converter, the output of which is connected to the current input of the three-phase current sensor, and the current output of the three-phase current sensor is connected to the synchronous motor [Patent No. 2354036. Sukhinin B.V., Surkov V.V., Egorov A.Yu., Domnin A.N., Surkov A.V. The method of controlling a valve motor and a tracking system for its implementation].

Such a valve motor allows for smooth and wide control of the shaft rotation speed, small torque pulsations and high efficiency. Static and dynamic characteristics with such a control scheme are completely analogous to the static and dynamic characteristics of a DC collector motor. However, with such a control scheme, the angle of rotation of the shaft of the valve motor is practiced with this control method is not optimal in accuracy.

An object of the present invention is to obtain the characteristics of a valve motor that are identical to the characteristics of a DC collector motor by analytically designing an optimal accuracy controller for the angle of rotation of the shaft of the valve motor.

This problem is solved by the fact that in the known method of controlling a rotary motor based on converting the angle of rotation of the shaft of a synchronous motor into a three-phase electric signal of the position sensor of the rotor of the motor, the amplitude of which is proportional to the control signal, and generating a three-phase voltage of the motor, the average value of which changes according to a sinusoidal law , the three-phase supply voltage is formed from the sign of the difference of the signal of the three-phase rotor position sensor of the synchronous motor and the signal Ala three-phase current sensor of the synchronous motor, and the control signal is formed by subtracting from the reference signal for the angle of the feedback signal for speed and the feedback signal for angle.

This method can be used in any servo system with a valve motor instead of a DC collector motor.

To clarify the method, we use the Gorev-Park equations in the coordinates d, q [AA Gorev. Transients of a synchronous machine. M .: SEI, 1950] for a synchronous motor with an excitation current I _f = const, supplemented by the gearbox equation:

,where υ is the angle of rotation of the rotor of the synchronous motor,

,

ρ = 120 ° - the angle of shift of the axes of the phase windings relative to each other,

R is the active resistance of the stator winding of the motor,

L is the induction coefficient along the longitudinal axis of the engine,

λ is the coefficient of explicit polarity,

J is the moment of inertia of the rotating masses,

M is the mutual induction coefficient between the stator and rotor windings,

m _em - electromagnetic torque of the motor shaft,

m _n - load moment on the motor shaft,

k _p - gear ratio

φ is the angle of rotation of the output shaft of the gearbox.

From equations (1) it follows that the synchronous motor is an object of regulation with two control actions: u _d and u _q . Using the theory of analytical design of regulators A.A. Krasovsky [Krasovsky A.A. Automatic flight control systems and their analytical design. - M .: Nauka, 1973. - 558 pp.] Or simpler to use, described in [VV Surkov, BV Sukhinin et al. Analytical design of optimal controllers according to the criteria of accuracy, speed, energy saving. - Tula: TulSU Publishing House, 2005. - 300 p.], We write the control law optimal for accuracy and at the same time optimal control law for the current controller i _d and the control law optimal for accuracy for the angle controller φ for m _n = 0 and θ = 0:

where U _m is the supply voltage of the Converter

i _dzad , ω _back or u _dzad = k ₂ · k · i _dzad , u _φzad = k ₂ · φ _zad - set values of control signals for the current regulator i _d and φ, respectively;

k ₂ - coefficient of proportionality, k ₂ > 0,

u _{q back} = u _{φ back} -k ₂ · φ-k ₂ · k ₃ · ω.

Variables in coordinates d, q are expressed in terms of variables in real coordinates A, B, C by means of relations (2), (3). For example, fictitious currents i _d , i _q correspond to real phase currents i _A , i _B i _C.

Using relations (2), (3), we find that differences u _{d back} -k ₂ · k · i _d and u _{q back} -k ₂ · k · i _q correspond to the difference u A _back -k ₂ · k · i _A , u _{B back} -k ₂ · k · i _B , u _{C back} -k ₂ · k · i _{C for} each phase of the motor and the optimal controls (4), (5) in coordinates d, q correspond to phase controls

Here

From formulas (6) - (8) it follows that the method under consideration requires a three-phase relay, a three-phase motor current sensor and a three-phase voltage switch (rotor position sensor), with the help of which a signal is generated that optimally controls the angle of rotation of the valve motor shaft.

The proposed method is implemented in a servo motor system containing a modulator, a three-phase synchronous rotor position sensor, a three-phase demodulator, a three-phase adder, a three-phase relay, a three-phase converter, a three-phase synchronous motor current sensor, a three-phase synchronous motor, the rotor of which is mechanically connected to the shaft three-phase rotor position sensor of a synchronous motor. The summing input of the three-phase adder is connected to the output of the three-phase demodulator, and the subtracting input is connected to the output of the three-phase current sensor of the synchronous motor, the output of the three-phase adder is connected to the input of the three-phase relay, the output of the three-phase relay is connected to the input of the three-phase converter, the output of which is connected to the current input of the three-phase synchronous current sensor motor, and the current output of a three-phase current sensor of a synchronous motor is connected to a synchronous motor. A gearbox with an angle sensor, a synchronous motor speed sensor, the rotors of which are mechanically connected to the shaft of the synchronous motor, and an adder with one summing and two subtracting inputs are additionally introduced into the servo system. The modulator input is connected to the output of the adder with three inputs. The first subtracting input of this adder is connected to the output of the synchronous motor speed sensor, the second subtracting input is connected to the output of the angle sensor of the synchronous motor, and the summing input is the control input of the valve motor by the rotation angle.

The invention is illustrated in the drawing, which presents a structural diagram of a servo system that implements a method of optimal accuracy of control of the angle of rotation of the shaft of the valve motor.

The system contains a series-connected adder 1 with one summing and two subtracting inputs, a modulator 2, the output of which is connected to the input of a three-phase rotor position sensor of the synchronous motor 3, the signal from which is fed to a three-phase demodulator 4, the output of a three-phase demodulator is connected to the first summing input of a three-phase adder 5 , the resulting signal from the output of the three-phase adder is fed to the three-phase relay 6, the relay output is connected to the input of the three-phase converter 7, the output of the three-phase converter For is connected to the input of a three-phase current sensor of a synchronous motor 8, its current output is connected to the input of a three-phase synchronous motor 9, the rotor of which is mechanically connected to the shaft of the three-phase position sensor of the rotor of the synchronous motor 3, with the shaft of the speed sensor of the synchronous motor 10 and through the gearbox 11 with the sensor shaft angle of the synchronous motor 12, the second subtractive input of the three-phase adder 5 is connected to the output of the three-phase current sensor of the synchronous motor 8, the output of the speed sensor of the synchronous motor 10 is connected to rvym subtractor input of the adder 1, the synchronous motor pickoff output 12 connected to the second subtractor input of the adder 1.

The system operates as follows. The voltage of the reference angle U _{φ back} (control signal) is supplied to the summing input of the adder 1, a voltage proportional to the rotation speed of the synchronous motor speed sensor (k ₂ · k ₃ · ω), for example, a tachogenerator 10, is applied to the second subtracting input of the adder 1 the input of the adder 1 is supplied with a voltage proportional to the angle of rotation of the sensor of rotation of the rotor of the synchronous motor 12 (k ₂ · φ). The rotor of the synchronous motor 9 is mechanically connected to the rotor of the speed sensor 10 and, through the gearbox 11, to the rotor of the angle sensor of the synchronous motor 12. At the output of the adder 1, the voltage U _in = U _φset -k ₂ · φ-k ₂ · k ₃ · ω, which is converted by the modulator 2 into a rectangular voltage of increased frequency (500-20000 Hz) with an amplitude value equal to U _input and fed to the excitation winding of the rotor position sensor of the synchronous motor 3, for example, selsyn, whose rotor is mechanically connected to the shaft of the speed sensor of the synchronous motor 10. FROM The ignal from the synchro synchronization windings is fed to a three-phase demodulator 4, at the output of which the voltage of the reference to the optimal controller appears:

where k ₁ is the total conversion coefficient of the modulator, rotor position sensor of the synchronous motor and demodulator, k ₁ = 1;

;υ is the angle of rotation of the rotor of the synchronous motor,

;

ω is the rotational speed of the rotor of the synchronous motor;

θ is the installation angle of the position sensor of the rotor of the synchronous motor relative to the rotor of the synchronous motor.

Using a three-phase adder 5, the three-phase voltage received from the three-phase current sensor 8 is subtracted from the output of the demodulator from the three-phase voltage (10) and fed to the input of the three-phase relay 6, the output signal of which is supplied to the input of the three-phase converter 7, the three-phase voltage appears at the output of the three-phase converter 7 u _A , u _B , u _C , changing in accordance with the optimal control law (6) - (9). As a three-phase converter, the circuit uses, for example, a three-phase bridge of six transistors (thyristors) that operate in key mode.

Using relations (2), (3), (9), we find u _d-back and u _{q-back of} controllers (4) and (5) corresponding to tasks (10):

In this case, the optimal controls (4), (5) take the form:

It follows from (13) that when the rotor position sensor is set to the zero position (θ = 0), the current regulator i _d stabilizes the current i _d at the zero level optimally in speed and maintains it optimally in accuracy so that i _d = 0. Moreover, equations (6) - (8) taking into account (9), (10) at θ = 0 are reduced to the form:

According to equations (15), a structural diagram is constructed (see Fig. 1).

Equations (1) taking into account (13), (14) with θ = 0 and k ₁ = 1 are transformed to

mind:

The obtained equations lead to the following conclusions. First, differential equations (16) are completely analogous to the differential equations of a DC collector motor. Therefore, the static and dynamic characteristics when controlling a valve motor according to the proposed method are completely similar to the static and dynamic characteristics of a DC collector motor. Secondly, it follows from equation (17) that with this method of controlling a valve motor, it additionally acquires the properties of a rotor turning angle that is optimal in accuracy.

The accuracy of modern automatic control systems is usually limited by a system error. The proposed method allows to reduce the error of automatic control systems to zero (theoretically). This increases the efficiency of automatic control systems and expands their functionality.

Claims (2)

1. The method of controlling a valve motor based on converting the angle of rotation of the synchronous motor shaft into a three-phase electrical signal of the rotor position sensor of the motor, the amplitude of which is proportional to the control signal, and generating a three-phase voltage of the motor, the average value of which varies according to a sinusoidal law, the three-phase voltage is formed from the sign of the difference between the signal of the three-phase rotor position sensor of the synchronous motor and the signal of the three-phase synchronous current sensor drive, characterized in that the control signal is formed by subtracting from the reference signal the angle of the speed feedback signal and the feedback angle signal. 2. Tracking system with a valve motor, comprising a modulator, a three-phase synchronous rotor position sensor, a three-phase demodulator, a three-phase adder, a three-phase relay, a three-phase converter, a three-phase synchronous motor current sensor, a three-phase synchronous motor, the rotor of which is mechanically connected to the shaft of a three-phase sensor the position of the rotor of the synchronous motor, characterized in that it additionally introduced a gearbox with an angle sensor and a speed sensor of the synchronous motor a rotor whose mechanically connected to the synchronous motor shaft, an adder with one summing and two subtracting inputs, a modulator input is connected to the output of the adder with three inputs, the first subtracting input of which is connected to the output of the synchronous motor speed sensor, the second subtracting input is connected to the output of the angle sensor synchronous motor, and the summing input is the control input of the valve motor by the angle of rotation.