CN201270497Y - Variable frequency and power frequency operation main circuit structure for three phase AC electric motor - Google Patents

Abstract

The utility model relates to a three-phase alternating current motor frequency changing and power frequency operation main return circuit structure, which is characterized in that the main return circuit is provided with three mutually-conversed return circuit structures under the time sequence control of each alternating current contactor. The three-phase alternating current motor frequency changing and power frequency operation main return circuit structure comprises a frequency changing operation return circuit, a power frequency starting return circuit and a power frequency operating return circuit, wherein the power frequency starting return circuit sets power-driven into a star-shaped connected main return circuit structure. The utility model achieves the switching of the motor frequency changing and the power frequency operation main return circuit and the star-shaped starting of power frequency operating through the alternating current contactor, further solves the problem of power frequency starting on the basis of integrating the advantages of power frequency operation and frequency changing operation, effectively lowers starting current of power frequency operation, and lightens big current and mechanism impact to a motor.

Description

Three-phase alternating-current motor frequency conversion, power frequency operation major loop structure

Technical field

The utility model relates to three-phase alternating-current motor operation major loop structure, especially is operated in the three-phase alternating-current motor operation major loop structure under the convertible pattern of frequency conversion and power frequency.

Background technology

At present, the three-phase alternating-current motor operational mode is converting operation or power frequency operation, is typically designed to three kinds of patterns, the one, only adopt the converting operation mode; The 2nd, only adopt the power frequency operation mode; The 3rd, can realize the switching of power frequency and converting operation mode.Using at present more is the first and second two kinds of operational modes.But first kind of mode exists that starting current is big, strong to electromechanical shock, the motor operation is subjected to grid supply quality to influence problems such as big; Though second kind of operational mode solved the problems referred to above,, in case the control appliance fault occurs, will make motor out of service, influence ordinary production, even can cause production accident; Though the third operational mode has solved the existing problem of preceding dual mode jointly, but, startup problem when the motor power frequency operation has often been ignored in existing circuit setting, and adopt direct Starting mode, thereby it is excessive still to exist starting current when power frequency operation, and motor is impacted strong problem.

The utility model content

The utility model is for avoiding above-mentioned existing in prior technology weak point, a kind of three-phase alternating-current motor frequency conversion, power frequency operation major loop structure being provided.Make and when power frequency operation, can effectively reduce starting current, alleviate big electric current and mechanical shock motor.

The utility model technical solution problem adopts following technical scheme.

The characteristics of the frequency conversion of the utility model three-phase alternating-current motor, power frequency operation major loop structure are that described major loop has three kinds of loop structures of conversion mutually under the sequencing control of each A.C. contactor, comprise that converting operation loop, power frequency start loop and power frequency operation loop; It is the major loop structure that is set to Y-connection with electronic that described power frequency starts the loop.

Design feature of the present utility model is that also described three kinds of loop structures of changing mutually are:

The converting operation loop, the converter power supply inlet wire contactor KM1 that is connected in series in the main power circuit, frequency converter, frequency converter output major loop contactor KM2 and motor windings end of incoming cables, the motor windings leading-out terminal constitutes the frequency conversion loop by A.C. contactor KM5 and motor windings end of incoming cables;

Power frequency starts the loop, and main power source directly inserts the motor windings end of incoming cables by A.C. contactor KM3, and A.C. contactor KM5 opens, with the closure formation star angle power frequency start-up circuit of motor windings leading-out terminal A.C. contactor KM4;

The power frequency operation loop, A.C. contactor KM3 keeps connecting, and A.C. contactor KM5 closure, motor windings leading-out terminal A.C. contactor KM4 disconnect, and constitute the power frequency operation major loop.

Compared with the prior art, the utility model beneficial effect is embodied in:

The utility model realizes that by A.C. contactor the switching of motor frequency change, power frequency operation major loop and the star of power frequency operation start, on the basis of synthetic power-frequency and converting operation advantage, further solve power frequency and started problem, effectively reduce the starting current of power frequency operation, alleviate big electric current and mechanical shock motor.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model.

Below pass through embodiment, and the utility model is described in further detail in conjunction with the accompanying drawings.

Embodiment

Referring to Fig. 1, in the present embodiment, major loop has three kinds of loop structures of conversion mutually under the sequencing control of each A.C. contactor, comprises that converting operation loop, power frequency start loop and power frequency operation loop; And it is the major loop structure that motor is set to Y-connection that power frequency starts the loop.

Shown in Figure 1, three kinds of loop structures of changing mutually are:

The converting operation loop, the converter power supply inlet wire contactor KM1 that is connected in series in the main power circuit, frequency converter, frequency converter output major loop contactor KM2 and motor windings end of incoming cables, the motor windings leading-out terminal constitutes the frequency conversion loop by A.C. contactor KM5 and motor windings end of incoming cables;

Power frequency starts the loop, and main power source directly inserts the motor windings end of incoming cables by A.C. contactor KM3, and A.C. contactor KM5 opens, with the closure formation star angle power frequency start-up circuit of motor windings leading-out terminal A.C. contactor KM4;

The power frequency operation loop, A.C. contactor KM3 keeps connecting, and A.C. contactor KM5 closure, motor windings leading-out terminal A.C. contactor KM4 disconnect, and constitute the power frequency operation major loop.

Before the system operation, the circuit breaker Q F that must at first close subsequently when KM1, KM2 closure, forbids KM3 and KM4 closure; When KM3, KM4 closure, and it is still closed to disconnect back, KM3 at KM4, and KM5 is when being closure, forbids KM1, KM2 closure.This structure is to realize interlocking between frequency conversion and two running statuses of power frequency.

After circuit breaker Q F closure, the major loop course of work is: at first KM2 and KM5 closure, and the KM1 closure inserts frequency converter in the Motor Control loop subsequently, and system realizes the variable frequency control to motor.Meanwhile, KM3 and KM4 are locked under the opening, realize safety interlocking by secondary control loop; When KM3 and KM4 closure, motor enters power frequency star start-up course, controls start-up time by secondary control loop, promptly controls the closing time of KM4.

Along with the disconnection of KM4, the closure of KM5, KM3 still remains on closure state, and this moment, motor entered the power frequency operation state.

Claims (2)

1, three-phase alternating-current motor frequency conversion, power frequency operation major loop structure is characterized in that described major loop has three kinds of loop structures of conversion mutually under the sequencing control of each A.C. contactor, comprise that converting operation loop, power frequency start loop and power frequency operation loop; It is the major loop structure that is set to Y-connection with electronic that described power frequency starts the loop.

2, three-phase alternating-current motor frequency conversion according to claim 1, power frequency operation major loop structure is characterized in that described three kinds of loop structures of changing mutually are:

The converting operation loop, the converter power supply inlet wire contactor KM1 that is connected in series in the main power circuit, frequency converter, frequency converter output major loop contactor KM2 and motor windings end of incoming cables, the motor windings leading-out terminal constitutes the frequency conversion loop by A.C. contactor KM5 and motor windings end of incoming cables;

Power frequency starts the loop, and main power source directly inserts the motor windings end of incoming cables by A.C. contactor KM3, and A.C. contactor KM5 opens, with the closure formation star angle power frequency start-up circuit of motor windings leading-out terminal A.C. contactor KM4;

The power frequency operation loop, A.C. contactor KM3 keeps connecting, and A.C. contactor KM5 closure, motor windings leading-out terminal A.C. contactor KM4 disconnect, and constitute the power frequency operation major loop.

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