SU1337968A1 - Method of reducing losses in induction electric motor - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to increase reliability and efficiency. This process is achieved in that in a method of reducing losses in an asynchronous motor, each time the magnitude of the voltage applied to an induction motor (BP) 2 changes, the rotation frequency n BP 2 is measured by the rotation speed sensor 3, the active power sensor 7 and the torque sensor 6, the active power P and the moment M on the shaft of the AD 2. According to the measured values, the coefficient of useful action, the power factor and their product are calculated. In the idle mode, each subsequent value of the power factor is compared with its previous value uttsim value, and in operation - each subsequent value of said product of its previous value. The change in the input voltage and its frequency is carried out in such a way that in idle mode the power factor and in the operating mode the specified product is maintained at max. at the level of As a result, the overturning of blood pressure 2 at low loads is avoided. Over the entire range of load variation, reactive energy consumption and active power losses are minimized. 1 il. 2 (L with 00 with Oi 00

Description

11337968

The invention relates to electrical engineering and can be used in asynchronous motors operating at variable load on the shaft.

The purpose of the invention is to increase reliability and efficiency.

Fa to the drawing shows a block diagram of a device that implements a method for reducing losses in an asynchronous motor.

The device contains an adjustable voltage and frequency source 1, the output of which is connected to an asynchronous motor 2. A rotating speed sensor 3 and a torque sensor 4 are installed on the shaft of the asynchronous motor 2. A sensor 5 is connected to the output of source 1 of an adjustable voltage. A signal proportional to cos V is generated at the output Q of the arithmetic unit 8, and a signal proportional to the product (j-cos,

The switch 9 depending on the state of the control input V switches one of the inputs D / to its output

10 or D, i.e. when V O at the switch output there is a signal from the input D, and when V l - a signal from the input D. The zero-body 10 generates a signal O at its output if

15, the signal at the input is equal to O, and the signal l is otherwise.

In the device, the method is implemented as follows.

When the asynchronous engine is in operation, the current sensor 6 and the active sensor 7 are 20 liters 2 in the idle mode of the torque power. The outputs of the sensors, for example, on the motor shaft are zero and, tracking 5, current 6, active power 7, convincingly, at the output of the torque sensor of rotation frequency 3 and moment 4 of jack 4, there will be a zero signal value, connected to the inputs of the arithmetic unit Therefore, on the control input 25 of the V switch 9 will be the level O and the input of the extreme regulator 11 switch 9 is connected to the input D, i. output 0 of the arithmetic unit 8. Arithmetic i: approx 8 is continuous- connected to the output of the sensor 4 moment. 30 but calculates by the expression of the output of the switch 9 is connected to the input of mi (1) and (2) and, therefore, to the extreme regulator I1, the two outputs of the extremal regulator 11 of which U, F are connected to the input receiving a signal proportional to the control voltage and frequency cos f of the induction motor 2. Extr respectively the source 1 regulator regulator 11 in the corresponding voltage and frequency. with the current value of cos (change voltage sensors 5, current 6, active power 7, rotation frequency 3 and moment 4 convert corresponding values to an analog or digital-40 signal and fed to the input of arithmetic 8 with two outputs Q ,, Q, which are connected to the information inputs D, Dj of the switch 9, the control input V of which is connected to the output of the zero-organ 10. Input zero -organ 10

the value of the controllable effect and, F in such a way as to maximize cos h.,

When the control influences and, F change, the values of voltage and frequency at the input of induction motor 2 change and, therefore, the value of cos (/ changes. Extreme unit 8, at the output of which signals are generated

Р / 1

cos y, (1)

 P-i..i .cos f -HT -; (/)

de P

and I

active power value; and, 1 are the values of the voltage and the motor current, respectively;

n is the value of the engine speed;

M - the value of the moment on the shaft of the engine

gatel; cosV is the power factor;

9 - coefficient of efficiency;

K - coefficient of proportion

The output Q of the arithmetic unit 8 generates a signal proportional to cos V, and the output O of the specified block is a signal proportional to the product (j-cos,

The switch 9 depending on the state of the control input V switches one of the inputs D / to its output

or D, i.e. when V O at the switch output there is a signal from the input D, and when V l - a signal from the input D. The zero-body 10 generates a signal O at its output if

the input signal is equal to O, and the signal l - otherwise.

the value of the controllable effect and, F in such a way as to maximize cos h.,

When the control influences and, F change, the values of voltage and frequency at the input of induction motor 2 change and, therefore, the value of cos (/ changes. Extreme regulator 11 determines the new values of control influences by the new value of cos f and the previous one. The process continues until i-jx until the found value of ow f f is maximized.

If the load on the shaft of the induction motor 2 differs from zero, then the output of the sensor 4 will be a signal, O | personal from zero as well

Consequently, the control input V of switch 9 - signal 1 and the input of extreme regulator II will receive a signal, the output of 7 ows V, and.

 g

traces of tesh.is), the extreme reg-ul-torus II will change the values of wiranlntsi to u, f as well as described until rj cos f is maximal. Proposal 11P 1 loss reduction method allows iiOBbfCMTij asynchronous motor operation reliability, since it eliminates ei o tilting in low load modes, while at the same time, the consumption of reactive energy and loss of active power are minimized.

Invention Formula

A method of reducing r 0 it7pb in an asynchronous electric motor, in which the measurement of Hgm is not the value of current and voltage at the terminals of an asynchronous electric motor with a subsequent change in the magnitude of the applied voltage, about M. M. Ii; i biH 4139/51

(Compiled by L. Golovchenko Tehred L. Oliynyk

Cor Pod

Circulation 659 VNISH1I USSR State Committee

on inventions and discoveries 1J033, Moscow, Zh-35, Raushsk nab., 4/5

Proichpolstenno-polygraphic enterprise, Uzhgorod, st. Design, D

7968

l and

1 And with that, for the purpose of overlap, efficiency and efficiency, while changing the magnitude of the applied voltage, the frequency of rotation of the asynchronous electric motor, the active power and the torque on its shaft are additionally measured, the measured values are calculated - 10 nor U1D, the coefficient of movability and their

in idle mode, each subsequent value of the power factor is compared with its previous value, and in operating mode, each subsequent value of the specified product is compared with its previous value and the shaft 1 is the source of the input voltage and its frequency so that in idle mode

70 strokes power factor, and in operating modes the specified work was maintained at the maximum level.

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Claims (1)

Claim A way to reduce losses in an induction motor, in which current and voltage are measured? at the terminals of the induction motor with a subsequent change in the magnitude of the input voltage, о τ η and more often, in order to increase the reliability and efficiency, with each change in the magnitude of the input voltage, the rotation frequency of the asynchronous motor, the active power and moment on its shaft, according to the measured parameters calculate the values of efficiency, power factor and their products, in idle mode, compare each subsequent value of the power factor with its previous value iem, and operating conditions are compared each subsequent value of said product with its previous value and changing the magnitude of applied voltage and its frequency so that the idling power factor, and in said operating modes of the product are maintained at a maximum level.