SU1277343A1 - Device for controlling rotational speed of rotor of induction motor - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to improve the accuracy of frequency control. This goal is achieved by introducing phase discriminator 17, logic circuits. 15I-2ILY-NOT, logic circuit 16, EXCLUSIVE OR, three logic circuits 18, 19, 20 AND-NOT into the device for controlling the rotor frequency of the synchronous electric motor. The mode of operation of the electric motor (motor, brake) is set by logic circuit 16, depending on the signs of the analog signals proportional to the slip and the frequency of rotation of the rotor. Single and zero signal levels corresponding to the sign of an analog signal proportional to slip are formed by a threshold circuit 13. Signals corresponding to the sign of an analog signal proportional to the rotation frequency are formed by the rotation direction determining unit included in the quad multiplier 9. The latter is connected pulse sensor 32 frequency vrapheni. The direction of rotation of the field vector is determined by the phase discriminator 17 and logic 15, depending on the ratio of the pulse frequency, tOsH from the converter 14, the frequency and the voltage from the driver, according to 9. When the device responds only to the sign of the analog signal cos, and (Л when ci) - only on the sign of the analog signal Wp. If the signs of the analog signals are the same, then the logic circuit 16 by the signal “Zero gives the command to add impulses SORIA and (Oz (

Description

The invention relates to electrical engineering and can be used in a frequency-controlled electric drive with a frequency converter and an asynchronous motor with a squirrel-cage rotor.

The purpose of the invention is to improve the accuracy of frequency control.

FIG. 1 shows a block diagram of a device for controlling the rotor speed of an induction motor; in fig. 2 - time diagrams.

The device (Fig. 1) contains a current converter 1, the outputs of which are connected to an asynchronous motor 2, an EMF formation unit 3, the output of which is connected to the control input of the current converter 1, two inputs of the EMF formation unit 3 connected to the harmonizer 4 output, and the third is connected to the output of the analog adder 5, the driver 6 sets phase currents, the output of which is connected to the control inputs of the current converter, and two inputs are connected to the outputs of the driver 4 harmonic signals, the third is connected to the output the slide controller 7, and the fourth to the setting current of the magnetizing current 8, the driver-quadrupler 9 by the first and second outputs is connected to the converter 10 frequency-voltage, the first input is connected to the first input of the pulse adder 11, which has three more inputs, the pulse adder 11 output connected to the input of the divider 12, the output of the converter 10 frequency-voltage is connected to the inputs of the slip controller 7 and the analog adder 5, the second input of which is connected to the input of the threshold circuit 13, the output of the slide controller 7 and raver 14 voltage-frequency.

In addition, the device contains logic 2I-2ILI-NOT-15, EXCLUSIVE OR 16, phase discriminator 17, three logical circuits AND-NOT 18, 19 and 20, while the input phase discriminator 17 is connected to the output of the voltage-frequency converter 14 and with the second input of the pulse adder 11, and the other input is connected to the first output of the imaging unit -header 9 and the first input of the pulse adder 11, the first inputs of the 2I-2ILI-NOT 15 circuit and the EXCLUSIVE OR 16 are connected to the output of the threshold circuit 13, the second inputs are connected to the second input of the reader 9, the output of the exclusive OR circuit 16 is connected to the third control; it has the input of a pulse adder 11, two other inputs of the 2I-2ILI-HE 8 circuit are connected respectively to the direct and inverse outputs of the phase discriminator 17, and the fourth input is combined with the fourth input of the pulse adder 11, the output of the 2I2ILI-NOT 15 circuit through the first 18 and second 20 I-NOT circuits is connected to the input of the harmonizer 4, (block 4 includes elements 22 and 23), and through the third IS-19 circuit it is connected to the other-last input second entrances second 20

and the third 19 circuits are NOT connected to the output of the divider 12.

In the particular case when the number of pulses arriving from the driver of the quadruple 9 corresponds to the size of the counter 21 of the generator of harmonic signals 4, the divider 12 from the device can be excluded. In this case, the second inputs of the circuits AND-NOT 20 and 19 are connected directly to the output of the pulse adder 11.

5 The phase current generation unit 6 consists of four digital-to-analog converters 24-27 and two analog adders 28 and 29. The EMF-forming unit 3 consists of two digital-analog converters 30 and 31. The input of the quad querifier 9 is intended for connection with a pulse speed sensor 32. The device works as follows. The mode of operation of the engine 2 (motor or brake) is defined by the scheme

5 EXCLUSIVE OR 16 depending on the signs of the analog signals proportional to the slip and the frequency of rotation of the rotor.

Single and zero signal levels corresponding to the sign of the analog signal,

0 proportional to the slip, are formed by the threshold circuit 13, and the signals corresponding to the sign of the analog signal proportional to the rotor rotation frequency are formed by a unit for determining the direction of rotation of the motor of the imaging unit 9.

5 The direction of rotation of the stator field vector is determined by the phase discriminator 17 and the 2I-2ILI-NOT 15 scheme depending on the ratio of the pulse frequency tojH from the voltage-frequency converter 14 and the Eriot of the quad factor 9.

With a)) p, the device responds only to the sign of the analog signal of the signal, and when a)) pw - only to the sign of the analog signal of the switch (Fig. 2).

5 The signal for setting the rotation frequency of the stator field vector in the form of a pulse frequency is generated as the sum or difference of two pulse sequences coming from the pulse speed sensor 32 through a quadruple former 9 and created from the slip controller 7 through the voltage converter 14 frequency. If the signs of the analog signals (Op and cos coincide (both are plus or both are minus), then the circuit is EXCLUSIVE OR 16 by the signal “O

5 gives the command for the addition of impulses i) ri - | - shzi, which corresponds to the motor mode of operation. When the signs sor and cos become oppositely polarized, the EXCLUSIVE OR 16 scheme by a signal “1 gives the command to subtract pulses and the engine goes into braking mode. In this case, if., Then coi «Yrn-WsH: and the engine operates in a brake-generator mode, when, simultaneously with a change in the direction of rotation of the stator field vector, provided by the phase discriminator 17 and the 2I-2IL-HE 15 circuit, the function changes subtraction and Yui Y; n-Srl. In this case, the engine switches from generator braking mode to anti-switch mode, providing effective braking. The pulse signal UJH, proportional to the frequency of rotation of the stator zero, is converted by shaper 4 into cosine / and sinwit harmonic signals (in codes). In this case, with a change in the signal at the output of circuit 2I-2IL-NOT 15, the alternation of the sequence of signals COS031 / and changes. The former 6, according to the specified analog signals and signals from the output of the harmonic wave former, generates the specified values of siiusoidal currents in accordance with the expressions Ia / pCosci) 1 / - () /; p cSoho) | / -ipSin (. At that, the amplitude of the specified currents / a and / ji is determined by the level of the signals iu const and the variable value / p proportional to MS. The generated set values of the common current vip and / p are fed in two-phase engine the inputs of the corresponding converters operating in the current source mode and connected to the stator windings of the engine (with a three-phase engine / & and if designation, are fed to the inputs of the coordinate converter and then to the converter inputs). Starting the engine in the forward direction of rotation On the input of the slip controller 7, a positive wired signal is generated by the signal; the voltage-frequency converter 14 generates a pulse sequence with a frequency depending on the level of the output module of the slide regulator. The pulse sequence specified is fed to one of the inputs of the phase discriminator 17. Since at the other input of the latter there are no pulses, the direct output of the phase discriminator generates the signal “1, and the inverse signal“ O. The threshold circuit 13 generates a signal “O, arriving at one of the inputs of the 2P-2ILI-NOT circuit, and if the signal“ O arrives from the maker 9, the signal “1 at the output of the circuit 2I-2PLI-NOT 15 resolves the passage impulse sequences through an AND-NOT scheme 19 pa the second input of the reversive fioro counter of the sinusoidal shaper and the shaper 4 generates a direct sequence of the driving currents. The rotor of the engine begins to rotate in the forward direction (Fig. 2). The sensor 32 generates a sequence of pulses, which is converted by the converter 10 into a high-speed analog signal (Fig. 2), which is fed to the other inputs of the slip controller 7 and the analog adder 5. In the analog adder 5, the speed signals from the output of the frequency-voltage converter 10 and the slip signal Wj, coming from the output of the slip controller 7, is summed up and the output signal of the adder 5 is supplied as a reference voltage to the digital-to-analog converters 30 and 31 of the EMF generator 3. In this case, the amplitude of the output signal of the imaging unit 3 EMF is determined by the output signal of the adder 5. At the inputs of the EXCLUSIVE OR 16 circuit, the signals are received from the threshold circuit 13 and from the quadruple 9. The signal EXCLUSIVE OR 16 outputs the signal "O. At the output of the pulse adder 11, a sequence of pulses is formed with a frequency (OiH (OpK + u) sn, equal to the sum of the 4-watl quadruple impulses frequency proportional to the analog tip speed signal and the frequency of the pulses of the transducer 14) proportional to to the signal) his. 1 torus skaters and) s. The sequence of pulses with the HIHC frequency of the output of an p.mp.11 of the clear adder 11 is supplied through divider 12 to the input of the former 4 harmonic signals and sets their frequencies). When the motor is reversed, the driver signal becomes negative, the voltage at the output of the slip torch regulator changes its sign from negative to positive. In this case, the phase of the active component of the given stator currents of the motor is changed by 180 °, the threshold circuit 13 is switched, which gives the signal "1". The scheme EXCLUSIVE ALREADY OR 16 gives a command on a half-time, 1s, and the summation node gives the difference of impulses co. and the shaper 6 sets the frequency of the current for the input of the current transducers for ;; ak) 1а1х currents to the other. than the frequency of the rotation of the rotor. Two brakes. When the rotor speed of the rotor decreases at the present, 1y (. That the frequency of the pulp1) Sov | iotora (Orc becomes smaller than the frequency of the slip pulses ((05, L- switches the phase discriminator, (.xsm; 2I2ILE-NOT 15 sdp.yum "About second current of current meter shaper current driver n pos: 1 ohms, 1H1 ii iimv.ibcoB with o | r: 1e.1 frequency iiocT ia to the first input of the reversible counter of current current shaper, as a result of which the alternation of the current task output signals, alternators currents feed the stator of the motor with a reverse turn When the phases are stopped, the engine is decelerated in counter-current mode (and further acceleration to the other side. At the same time, the engine power frequency is proportional to (OjH - / (1) 5n -WpH /.

With a change in the direction of rotation of the engine, the sign of w / changes, but from the forking quadrant 9, the EXCLUSIVE OR 16 scheme issues a signal "O, the summation node sets the frequency ixijH tipH + W3K and the engine accelerates to the specified speed in the direction of reverse.

The drive stops when the driver is removed when the signal is removed. The output of the slip controller, by the action of the feedback signal, becomes negative if the rotor of the engine has previously been rotated in the direction of reverse rotation. In this case, the process of braking the rotor of the engine to a bullet speed is the same as after the command to reverse in the direction of forward rotation.

In this device in the control loop between the pulse speed sensor and the driver for setting the stator current of the engine there are no nonlinear links and elements that change their parameters from operating conditions, temperature conditions and speed control.

An introduction to the proposed device of a phase discriminator, 2I-2IL-NOT and EXCLUSIVE OR circuits, their connection scheme and the use of information about the rotor position in a pulsed form, as well as the formation of numerical form of sinusoidal current signal on the basis of their current electric drive.

The proposed device also ensures stable operation of the electric drive with deep regulation of the rotor speed, in which instead of block 10 the frequency-voltage, which forms an analog signal proportional to the rotation frequency of the rotor, uses a tachogenerator.

Claims (1)

Invention Formula A device for controlling the rotor speed of an asynchronous motor, motor, contains a current converter whose outputs are intended for connection to an induction motor, an EMF forming unit whose output is connected to the control inputs of the current converter, two EMF forming unit inputs are connected to the output of the driver harmonic oscillations (signals), and the third - to the output of the analog adder, the driver of the phase currents, the output of which is connected to the control unit, the inputs of the current converter, and two inputs are connected to the outputs of the harmonic wave former, the third is connected to the output of the slip controller, and even the output is connected to the magnetizing current setpoint generator, the quadrupler, the input of which is intended for connecting to a pulse speed sensor, and the first and second outputs of the connector with a frequency converter are voltage, the first output is connected by the first input of a pulse adder, having three inputs, a pulse adder c) 1ho ohm connected to the input of the divider, the output of the frequency converter - voltage is connected to the inputs of the slip controller and analog adder, the second input of which is connected to the input of the threshold circuit, the output of the slide controller and the input voltage-variable frequency is different because the purpose of increasing the accuracy, it introduced phase phase 0 discriminator, 2I-2LINE logic circuits, EXCLUSIVE OR, three AND-NOT logic circuits, with the first input of the phase discriminator connected to the output of the converter –– frequency – frequency and to the second input of the impulse1) of the Clear adder, and the other input is connected to the first the output of the driver mapper and the first input of the pulse adder, the first inputs of the 2I-2OR or NO circuit are EXCLUSIVE OR connected to the output of the threshold circuit, the second inputs of the connector with the second output of the mapper former, the output of the circuit EXCLUSIVE OR is connected to the third Owner Yunhemu input impulse | o adder, the other two inputs of the circuit 2I-2ILI-NOT connected respectively to g direct and inverse outputs of the phase discriminator, and the fourth input is combined with the fourth input of the pulse adder, the output of the 2I-2IOTI-NOT circuit through the first and second I-PE circuits is connected to the input of the harmonic signal generator, and through the t1) I and I circuit NOT connected to the other input of the latter, the second inputs of the second and third circuits AND-NOT connect with the output share; 1I.