CN87217217U

CN87217217U - Frequency- change-source device

Info

Publication number: CN87217217U
Application number: CN 87217217
Authority: CN
Inventors: 谭颂
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-26
Filing date: 1987-12-26
Publication date: 1988-11-02

Abstract

The utility model discloses a frequency-changing power source device used for a common three-phase induction motor as the stepless speed regulation. The frequency-changing power source device comprises a main-loop full-wave rectifying circuit and a three-phase inversion bridge. A control loop adopts the method of the P W M modulation, the waveform of the output voltage and electric current can close on the sine wave, and a motor has less heat productivity and big torque. The control loop comprises a special frequency-arranging circuit, an annular allotter, a waveform conversion circuit, a three-phase synchronous A G C circuit and a P W M modulator, and all circuits comprise transistors and integrated blocks. The utility model has the advantages of small size, light weight, high reliability and convenient operation, and can be used widely for the laboratory and the industrial production.

Description

Frequency- change-source device

The utility model is to make the used frequency changing power device of stepless time adjustment about three-phase alternating-current motor.

Existing frequency changing power device, the speed governing frequency changing power device of making as Tianjin Design and Research Institute of Electric Drive is the thyristor inversion bridge, output waveform is a square wave, cause the high order harmonic component amount big, make motor increase extra heating and torque reduction, and because the circuit complexity, the volume of equipment is very big, and price is very high.The utility model frequency changing power device, adopt Sine Wave Pulse Width Modulation mode (PWM), make output voltage and current waveform near sinusoidal wave, the high order harmonic component amount is few, has solved by the square wave power supply shortcoming that the motor feels hot and torque reduces, improved the performance of motor operation, and because major loop and control loop are fairly simple and stable, thereby make the volume of this device little, (be said apparatus 1/12) is in light weight, cost is low, the reliability height.

Dalian Electric Machine Factory introduces Japanese Toshiba Corporation complete set technology and equipment recently.Produce the VT130G1 frequency converter and also adopt Sine Wave Pulse Width Modulation mode control circuit, also with the microprocessor programming, but price is very high.The utility model frequency changing power device, control loop adopts homemade linear amplifier pipe built-up circuit, though its circuit is complicated than microprocessor, its cost is low, (be above-mentioned frequency changing power device price about 1/4) stable performance, is convenient to inspection and maintenance again.

The circuit block diagram of this frequency changing power device is seen accompanying drawing 1, and symbol description is as follows among the figure: a is three phase full wave rectification and filter circuit; B is a rectifying voltage regulator; C is a three phase inverter bridge; E is a frequency setting circuit; F is the V/f converter; G is a ring distributor; H is the waveform transformation circuit; I is three synchronised auto-gain circuits; J is the PWM modulator; P is a triangular-wave generator.N is the electric moter voltage feedback circuit; K is a preamplifier; M is a clamp circuit; D is common threephase motor.

This frequency changing power device is made up of major loop a, C and control loop e, f, g, h, i, j, p, k, m, n. Major loop a is that three phase full wave rectification and filter circuit form. Obtaining high voltage direct current by a is added among the C of loop. Loop C is three phase inverter bridge, and it makes the high voltage direct current inversion under the effect of control circuit be the three phase mains of Sine Modulated (PWM), supplies with motor d. Because the frequency of control loop is continuously controllable, the frequency of being defeated by like this three phase mains of motor d also changes thereupon. The pass of motor speed N and input power frequency f is: N=(60f)/(p) (p is the motor number of pole-pairs), therefore adjust the rotating speed that supply frequency is the capable of regulating motor.

Control circuit provides a DC potential by frequency setting circuit e.This current potential is added on the V/f converter f.Produce pulse signal obtains 120 ° of three phase phasic differences through ring distributor g square wave by f.These three square waves separately through separately waveform transformation circuit h, obtain the sine wave of 120 ° of three phase differences again.After the control of this sine wave through three synchronised auto-gain circuit i, the triangular wave of being exported sinusoidal wave and that produced by triangular-wave generator p is added on the PWM modulator j together, obtains sinewave modulation signal on the output of j.This signal is defeated by the three phase inverter bridge C in the main control loop after preamplifier K strengthens signal, the three phase mains after the inversion is supplied with motor d.Circuit m is that clamp circuit can be made of a comparison circuit.Circuit n is the motor feedback circuit, and it is made up of a transformer and full-wave rectification bridge.M and n provide control signal for three-phase automatic gain control circuit i.Circuit b is a rectifying voltage regulator, the working power of its supply control circuit.

The embodiment of this frequency changing power device sees accompanying drawing 2, accompanying drawing 3.Multiturn potentiometer W1 in the accompanying drawing 2 is exactly a kind of form of frequency setting circuit e.Be added on the V/f converter f at the current potential of obtaining on the W1.This converter circuit is made up of BG1, A1, A2 in the accompanying drawing 2.The current potential that is come by W1 carries out the voltage/frequency conversion behind resistance R 3 and capacitor C 1 integration.The effect of integration is that the variation of output pulse signal is smoothly stablized when adjusting.Pulse signal is defeated by g by f, and g is a ring distributor, and this distributor is made up of BG4 to BG14 among Fig. 2.Obtain the square wave (FA, FB, FC) of 120 ° of three phase differences from three bistable circuit outputs.Constitute a start automatic reset circuit by BG13, BG14 in ring distributor, this circuit is closed ring distributor immediately after the zero clearing when start.Make three bistable circuits by specifying the logic upset like this.

The circuit that GB15, A4, A5 form in the accompanying drawing 3 is a kind of form of waveform transformation circuit h, and its effect is that the square wave that will import becomes sine wave.Resistance R 56 in parallel in the integrating circuit under its circuit is so that output waveform still is sinewave output when incoming frequency changes.This sine wave is defeated by three-phase automatic gain control circuit i.

The circuit that BG17, BG18, A6 form in the accompanying drawing 3 is a kind of form of three-phase automatic gain control circuit i.This circuit is formed the size that three branch roads are controlled the three-phase sine-wave signal simultaneously by three groups of BG17, BG18, A6.This circuit has two effects.Three of the sine wave of first output is on good terms the while, controlled synchronously, can obtain three pwm signals that pulse duration is identical behind the PWM modulator, makes the three-phase mains voltage balance of being defeated by motor.The second feedback signal n from clamp circuit m and motor power imports from three synchronised automatic gain control circuit Ez end.The requirement of voltage when making the common threephase motor frequency control of the voltage conforms of being defeated by motor.When frequency was lower than 50HZ, output voltage and frequency were that the ratio of voltage and frequency is a fixed number; When being higher than 50HZ, output voltage is normal value.

A7, A8, BG22, BG23, BG24, BG25 form PWM modulator j in the accompanying drawing 3, and the triangular-wave generator p among Fig. 1 is defeated by the PWM modulator to triangular signal sp end from Fig. 3.Compare with the sine wave signal from i at PWM modulator intermediate cam ripple signal, so produce the PWM modulation signal, this signal BG22, BG24 in Fig. 3 are coupled to preamplifier by optical coupler BG23, BG25 after amplifying, i.e. K among Fig. 1.Its physical circuit is seen Fig. 3, is made up of BG19, BG20, BG26, BG27, and this circuit is owing to use optical coupler thereby have good buffer action.In addition match with independent current source V1, V3, V4, V5 that rectifying voltage regulator is provided isolation between the three phase mains of just having realized isolation between high-tension circuit and the control circuit and motor is to guarantee the circuit operate as normal.

Owing to adopted foregoing circuit and structure, make to the utlity model has that volume is little, in light weight, little power consumption, simple in structure, use and keep in repair characteristics such as also convenient, and cost is low.

The key technical indexes is as follows:

The input power supply: three-phase or single-phase 380V ± ^10% _15%50H _Z-60H _Z

Input power: change with power output.

Output frequency: 10H _Z-120H _ZAdjustable continuously.

Output voltage-frequency ratio: 50H _ZThe certain 50H of following V/F _ZAbove V is certain

Output voltage: 10H _Z-50H _ZThe time 75V-380V

50H _Z-120H _ZThe time voltage be 380V

Claims

1, a kind of frequency changing power device, form by major loop a, c and control loop, it is characterized in that control loop is made up of frequency setting circuit e, v/f converter f, rectifying voltage regulator b, ring distributor g, waveform transformation circuit h, three synchronised automatic gain control circuit i, triangular-wave generator p, electric moter voltage feedback circuit n, preamplifier k, clamp circuit m, PWM modulator j.

2, frequency changing power device according to claim 1 is characterized in that V/f converter f is made up of BG1, A1, A2, has a RC integrating circuit in the V/f converter.

3, frequency changing power device according to claim 1 is characterized in that ring distributor g is made up of BG4 to BG14, and BG13, BG14 constitute a start automatic reset circuit.

4, frequency changing power device according to claim 1 is characterized in that waveform transformation circuit h is made up of BG15, A4, A5, and Ji divides Dian Lu And to join a resistance R 56 under it.

5, frequency changing power device according to claim 1 is characterized in that three synchronised automatic gain control circuit i form three circuit by three groups of BG17, BG18, A6, control the size of sine wave signal simultaneously.

6, frequency changing power device according to claim 1, it is characterized in that PWM modulator j is made up of A7, A8, BG22, BG24 and optical coupler BG23, BG25, and optical coupler matches with independent current source V1, V3, V4, V5 that rectifying voltage regulator is provided, realizes between high-tension circuit and the control circuit and the isolation between the three phase mains of motor.