RU2169426C1 - Induction-motor drive control gear - Google Patents

Abstract

FIELD: controlling speed of machines and miscellaneous mechanisms equipped with induction motors. SUBSTANCE: newly introduced in control gear is adaptive speed governor that has common bus connected to microprocessor, random- access memory, read-only memory, address selector, and data transceiver. Output bus of the latter is connected to two data registers, series-connected analog-signal multiplexer, analog-to-digital converter, and digital-signal input device whose output is connected to input bus of transceiver. It also has digital-to-analog converter connected to first-register output, as well as counter whose input is connected to output of feedback signal shaper and output, to second input of digital-signal input device; output of digital-to-analog converter is connected to input of speed governor; outputs of address selector are connected to enable inputs of registers and to address inputs of digital-signal input device; analog-signal multiplexer inputs are coupled with phase-current sensors of induction motor and address inputs, with second-register output. EFFECT: improved transient characteristics of electric drive due to damping elastic vibrations. 2 dwg

Description

 The invention relates to electrical engineering, namely to the control of AC electric drives with elastic connections by changing the frequency and magnitude of the stator power currents, and can be used to control the speed of machines, fans and other machines and mechanisms equipped with induction motors.

 Closest to the proposed device is an AC electric drive containing an induction motor, a speed controller connected in series, a coordinate converter and an energy converter, the output of which is connected to the stator winding of the induction motor, an angle sensor mechanically connected to the rotor of the induction motor, a reactive current regulator, the output of which is connected to the corresponding input of the coordinate transformer and the first input of the rotor current frequency driver, in the second input of which is connected to the output of the speed controller, and the output of the rotor current frequency driver is connected to the corresponding input of the coordinate converter, a sinusoidal signal generator, the outputs of which are connected to the reference signal inputs of the coordinate converter, the frequency multiplier whose input is connected to the angle sensor, and the outputs are connected to corresponding inputs of the speed controller and coordinate converter, as well as the reference signal generator [1].

 The disadvantage of this technical solution is the lack of damping of elastic vibrations of the induction motor and actuator, since the AC electric drive does not provide control and regulation of the elastic moment and speed of the actuator. High oscillation of the working bodies of machines and mechanisms leads to an increase in the time of transients in dynamic modes of operation, i.e. to a decrease in productivity, as well as to a deterioration in the quality of products.

 The invention is aimed at improving the dynamic performance of the electric drive by damping elastic vibrations.

 This is achieved by the fact that in the device for controlling an asynchronous electric drive, comprising an asynchronous motor connected via an elastic transmission to an actuator, a speed controller, a coordinate converter and an energy converter connected in series to each other, the output of which is connected to the stator winding of the induction motor, an angle sensor, mechanically associated with the rotor of an induction motor, a reactive current generator, the output of which is connected to the corresponding input of the converter the ordinate and the first input of the rotor current frequency generator, the second input of which is connected to the speed controller output, and the rotor current generator frequency output is connected to the corresponding input of the coordinate converter, the sinusoidal signal generator, the outputs of which are connected to the inputs of the reference signals of the coordinate converter, the feedback signal shaper speed and movement, the input of which is connected to the angle sensor, and the outputs are connected to the corresponding inputs of the speed controller and coordinate converter at, as well as a reference signal generator, an adaptive controller is introduced, containing a common bus to which a microprocessor, random access memory, read-only memory, address selector and data transceiver are connected, to the output bus of which are two data registers connected in series to an analog signal multiplexer, analog-to-digital converter and digital signal input device, the output of which is connected to the input bus of the transceiver, digital-to-analog converter, connect the output of the first register, as well as a counter whose input is connected to the output of the feedback driver, and the output is connected to the second input of the digital signal input device, the output of the digital-to-analog converter is connected to the input of the speed controller, the outputs of the address selector are connected to the enable inputs of the registers and the address the input of the digital signal input device, the three inputs of the analog signal multiplexer are connected to the phase current sensors of the stator of the induction motor, and the address inputs are connected to the output of the second Istra.

 In FIG. 1 is a diagram of a device for controlling an asynchronous electric drive with elastic coupling, FIG. 2 - structure of an adaptive controller.

 The device comprises an asynchronous motor 1, connected through an elastic transmission with an actuator 2, sequentially connected to each other by a speed controller 3, a coordinate converter 4 and an energy converter 5, the output of which is connected to the stator winding of the motor 1, an angle sensor 6, mechanically connected to the rotor of the electric motor 1 , a reactive current setter 7, the output of which is connected to the corresponding input of the converter 4 and the first input of the rotor current frequency generator 8, the second input of which is connected to the output p the regulator 3, and the output of the shaper 8 is connected to the corresponding input of the converter 4, the shaper 9 of the sinusoidal signals, the outputs of which are connected to the inputs of the reference signals of the converter 4.

 The speed and displacement feedback generator 10 comprises a frequency multiplier 11 and a digital-to-analog converter 12. The input of the multiplier 11 is connected to the sensor 6, and the outputs are connected to the corresponding inputs of the converters 4 and 12. The output of the converter 12 is connected to the input of the controller 3.

 Three inputs of the adaptive controller 13 are connected to the sensors 14, 15, 16 of the phase currents of the stator of the motor 1, the fourth input is connected to the output of the multiplier 11, and the output is connected to the input of the controller 3. The outputs of the reference signal generator 17 are connected to the corresponding inputs of the converter 4, shapers 8, 9 and multiplier 11.

 Adaptive controller 13 contains (Fig. 2) a common bus (OS), to which a microprocessor 18, random access memory 19, read-only memory 20, address selector 21 and data transceiver 22 are connected, to the output bus of which data registers 23 and 24 are connected, a series-connected multiplexer 25 of analog signals, an analog-to-digital converter 26 and a device for inputting digital signals 27, the output of which is connected to the input bus of the transceiver 22, a digital-to-analog converter 28 connected to the output of the reg Stra 23, and the counter 29 having an input coupled to the output of the feedback signals 10, and an output connected to the second input of the input device 27.

 The output of the converter 28 is connected to the input of the speed controller 3 of the electric drive. The outputs of the selector 21 are connected to the enable inputs of the registers 23 and 24 and the address input of the input device 27. Three inputs of the multiplexer 25 are connected to the sensors 14, 15, 16 of the phase currents of the stator of the induction motor, and the address inputs are connected to the output of the register 24.

 The device operates as follows.

The stator reactive current _command signal U _d is generated by the setter 7. The stator active current _command signal U _q is determined by the difference between the speed reference signal U _{s and the} feedback signal U _ocl for rotor speed, as well as the adaptation signal U _a .

где A - коэффициент пропорциональности.The signal for setting the amplitude of the stator current is determined by the expression:

where A is the coefficient of proportionality.

Stator current frequency
f _m = f _ck ± f _ω1 , (5)
where f _SK - the frequency of the rotor currents at the output of the shaper 8, proportional to the signal U _q ;
f _ω1 is the additional frequency proportional to the frequency ω _{1 of} rotation of the rotor and formed by the multiplier 11.

At the output of the converter 4, signals I _alз , I _blз , I _{clз are formed} , which act as signals for setting the stator phase currents. These signals are fed to the input of the converter 5, which supplies the stator with currents I _al , I _bl , I _{cl of a} given amplitude U _Зm and frequency f _m .

From the current sensors of the phases of the stator of the motor 1 and the multiplier 11, respectively, information on currents I _al , I _bl , I _cl and an additional frequency f _{ω1 are received} at the corresponding inputs of the adaptive controller 13. The controller 13 operates as follows.

 The microprocessor 18 in each cycle of information exchange gives the address A to the common bus and then, through the control signals, Output and Input, data D is exchanged between the microprocessor 18 and that block of the adaptive controller 13, the operation of which is allowed by the selector 21 in accordance with address A. Random access memory 19 serves to store the calculated data, read-only memory 20 for storing the operating system and control program.

According to the control signal Output to the register 24 is written a code, according to which the input of the converter 26 receives an analog signal from a current sensor I _al . According to the control signal, the input of a digital code from the output of the converter 26, proportional to the signal I _al , through the input device 27 and the transceiver 22 enters the microprocessor 18. Next, similar output and input cycles allow the microprocessor to obtain information about the current values of currents I _bl , I _cl .

The input of the counter 29 receives pulses of frequency f _ω1 from the shaper 10 of the feedback signals. At the output of the counter 29, a digital code is generated proportional to the current movement Φ _{1 of the} rotor of the engine 1. According to the address signal from the output of the selector 21 and the control signal, the Enter movement code through the input device 27 and the transceiver 22 is transmitted to the microprocessor 18.

U_а=-k₁•M_у, (3)
где M_∂ момент асинхронного двигателя 1;
W_эм - электромагнитная энергия обмоток двигателя 1;
Φ₁,Φ₂ - углы поворота ротора двигателя 1 и механизма 2;
n - число обмоток;
Ψ_j, l_j - потокосцепление и ток j-ой обмотки;
l_j ⁽²⁾ Ψ $\genfrac{}{}{0ex}{}{\text{(}}{\text{j}}$ ²⁾ ,R_j ⁽²⁾ - ток, потокосцепление и активное сопротивление j-ой обмотки ротора;
L_j,k - взаимная индуктивность j-ой и k-ой обмоток;
I_k - ток k-ой обмотки;
М_у - упругий момент;
c - жесткость упругой передачи;
ω₁,ω₂ - частоты вращения ротора двигателя 1 и механизма 2;
J₁,J₂ - моменты инерции ротора двигателя 1 и механизма 2;
U_а - сигнал адаптации;
k₁- коэффициент пропорциональности.The microprocessor 18, based on the obtained information about the movement Φ _{1 of the} rotor and phase currents I _al , I _bl , I _cl calculates the current values of the moment M _{d of the} asynchronous motor 1, the angle Φ _{2 of} rotation and the frequency ω _{2 of} rotation of the actuator 2, the elastic moment M _y , as well as the adaptation signal U _a in accordance with the expressions:
M _∂ = ∂W _em / ∂Φ ₁ ;

U _a = -k ₁ • M _y , (3)
where M _∂ moment of induction motor 1;
W _em - electromagnetic energy of the motor windings 1;
Φ ₁ , Φ ₂ - rotation angles of the rotor of the engine 1 and mechanism 2;
n is the number of windings;
Ψ _j , l _j - flux linkage and current of the j-th winding;
l _j ⁽²⁾ Ψ $\genfrac{}{}{0ex}{}{\text{(}}{\text{j}}$ ²⁾ , R _j ⁽²⁾ - current, flux linkage and active resistance of the j-th rotor winding;
L _{j, k} is the mutual inductance of the jth and kth windings;
I _k is the current of the kth winding;
M _y - elastic moment;
c is the stiffness of the elastic transmission;
ω ₁ , ω ₂ - rotational speed of the rotor of the engine 1 and mechanism 2;
J ₁ , J ₂ - moments of inertia of the rotor of the engine 1 and mechanism 2;
U _a - adaptation signal;
k ₁ - coefficient of proportionality.

The digital code obtained as a result of the calculation, which corresponds to the adaptation signal U _a , by the enable signal from the selector 21 and the control signal, The output is recorded in register 23, fed to a digital-to-analog converter 28 and converted into an analog adaptation signal U _a , which is fed to the input of controller 3, which provides closure of negative feedback on the elastic moment M _y .

The moment feedback M _y acts as follows. With a positive signal U _ss , setting the speed, the appearance of the moment M _{at a} positive polarity means that the actuator due to the elastic coupling lags behind the motor. To align the angles Φ ₁ , Φ ₂ it is necessary to reduce the speed ω ₁ ; the task to reduce the speed Δω _l is automatically provided directly proportional to the value of M _y due to the presence of the corresponding negative feedback on the elastic moment in the form of an adaptation signal U _a .

Similarly, the moment feedback acts for all other combinations of the signal polarities U _ss and M _y - in the direction of alignment of the angles Φ ₁ , Φ ₂ and, accordingly, stabilization of the signal M _{y in} both static and dynamic modes of operation. Due to this, damping of the oscillations of the frequency ω ₁ of the rotor of the induction motor and the speed ω _{2 of the} actuator is ensured.

 The proposed technical solution provides an improvement in dynamic performance due to the damping of the elastic vibrations of the electric drive, which allows to reduce the time of transient processes during start-up, braking, and reverse.

 The effectiveness of using the proposed technical solution is determined by increasing the productivity of machines and mechanisms with elastic couplings equipped with asynchronous motors, due to the reduction of transient times in dynamic operating modes, as well as improving the quality of products by reducing the oscillation of the working bodies in static mode.

Sourse of information
1. A. p. USSR N 1054863, class H 02 P 5/34, H 02 P 7/42. Publ. in BI N 42 11/15/83.

Claims (1)

A device for controlling an asynchronous electric drive, comprising an asynchronous motor connected via an elastic transmission to an actuator, connected in series to each other by a speed controller, a coordinate converter and an energy converter, the output of which is connected to the stator winding of the asynchronous motor, an angle sensor mechanically coupled to the rotor of the asynchronous motor, reactive current regulator, the output of which is connected to the corresponding input of the coordinate transformer and the first input a rotator of the frequency of the rotor currents, the second input of which is connected to the output of the speed controller, and the output of the frequency generator of the currents of the rotor is connected to the corresponding input of the coordinate converter, a sinusoidal signal generator, the outputs of which are connected to the inputs of the reference signals of the coordinate converter, a driver of feedback signals for speed and movement, the input of which is connected to the angle sensor, and the outputs are connected to the corresponding inputs of the speed controller and coordinate converter, as well as the generator of supports s signals, which outputs are connected to corresponding inputs coordinate converter, frequency generator rotor current, generator of sinusoidal signals and the feedback signal generator speed and the displacement, characterized in that the introduced adaptive controller comprising a common bus to which are connected
a microprocessor that calculates, based on information about the rotor movement and stator phase currents, the current values of the asynchronous motor torque, rotation angle and rotational speed of the actuator, elastic moment, as well as the adaptation signal, random access memory, address selector and data transceiver, to the output bus of which two data registers connected in series by an analog signal multiplexer, an analog-to-digital converter and a digital signal input device, the output of which is dinene with the input bus of the transceiver, a digital-to-analog converter connected to the output of the first register, as well as a counter whose input is connected to the output of the feedback driver, and the output is connected to the second input of the digital signal input device, the output of the digital-to-analog converter is connected to the input of the speed controller, outputs address selector - with enable inputs of the registers and address input of the digital signal input device, three inputs of the analog signal multiplexer are connected to the current sensors from the stator of the induction motor, and the address inputs with the output of the second register.

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