CN1317817C

CN1317817C - Time-sharing starting method of three-phase AC asynchronous motor

Info

Publication number: CN1317817C
Application number: CNB2004100466328A
Authority: CN
Inventors: 沈进
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-08-04
Filing date: 2004-08-04
Publication date: 2007-05-23
Anticipated expiration: 2024-08-04
Also published as: CN1599229A

Abstract

The present invention relates to a time-sharing start-up method for three-phase alternating current (AC) asynchronous motors, which is a start-up method of controlling voltage. In the present invention, when a three-phase asynchronous motor is started, the AC sine voltage of a three-phase power supply is controlled in shared time to apply to the motor; at the time when the instantaneous voltage difference of any two of A, B and C phases is zero, the voltage of the two phases is switched on to apply to two corresponding input terminals of the motor; at this time, the voltage of another phase is not communicated with the motor, and the voltage of another phase is turned on to apply to another corresponding input terminal of the motor until the instantaneous voltage value of is zero after a period of time. The method of the present invention has the advantages that starting current is greatly reduced under the precondition that an enough starting torque of a three-phase asynchronous motor is ensured, the starting current can be reduced below 1.6 to 1.8 times of rated operating current, and accordingly, impact caused when a three-phase asynchronous motor is started on network voltage and other electric devices is reduced.

Description

Three-phase AC asynchronous motor timesharing startup method

Technical field:

The present invention relates to a kind of three-phase AC asynchronous motor startup method, particularly three-phase AC asynchronous motor timesharing startup method.

Background technology:

Three-phase AC asynchronous motor is simple in structure with it, low price can adapt to various operational environments and be used widely.At present, the startup method of three-phase AC asynchronous motor have direct startup, Y-Δ start, from lotus root reduced-voltage starting and soft start.Directly startup, Y-Δ start and belong to traditional startup method from the lotus root reduced-voltage starting, these startup methods or exist starting current big or exist detent torque to reduce, the shortcoming that is difficult to start, when for example directly starting, starting current normally rated current 5-8 doubly, so huge starting current will be given power supply grid, motor and the transmission mechanism equipment that drags brings very big impact, has a strong impact on the power supply quality of electrical network; Have a strong impact on the useful life of motor and plant equipment, make the excessive waste electric power resource of net capacity surplus simultaneously.Therefore, the research of great amount of manpower and material resources to new shape startup method is dropped in countries in the world, is intended to solve the excessive problem of electric motor starting electric current.The 1980s, people have invented a kind of starting device that is referred to as soft start, and the method that this equipment adopts high-power electronic device that three-phase alternating-current supply is carried out copped wave realizes reducing the purpose of starting current.So-called copped wave is meant the method that the switching pulse of employing certain frequency carries out opening and closing to controlled device (three-phase alternating-current supply).Soft start is actually a kind of a kind of reduced-voltage starting that pulse duty factor realizes step-down that changes so.Soft start normally needs the user according to the motor load situation following parameter to be provided with: soft start reference voltage, soft-start time, kick starting resistor, soft stop reference voltage, soft stop time, cut-off current.Therefore this method uses very miscellaneously, uses inconveniently, and the starting device expense is higher.

Summary of the invention:

Purpose of the present invention is to provide a kind of threephase asynchronous startup method, can guarantee enough detent torques, makes the motor smooth starting, can greatly reduce starting current again, overcomes the above-mentioned shortcoming of prior art.

Technical solution of the present invention is a kind of three-phase AC asynchronous motor timesharing startup method, it is a kind of startup method of controlling voltage, it is when threephase asynchronous starts, timesharing control three phase mains AC sine wave voltage puts on motor input terminals, at A, B, appointing two-phase instantaneous voltage difference in the C three-phase voltage was zero moment, connect the corresponding two-phase input that this two-phase voltage puts on motor, this constantly, another phase voltage is disconnected motor, when delay a period of time to another phase voltage instantaneous value is zero, just connects another phase voltage and put on another corresponding input of motor.

Description of drawings:

Fig. 1 is three-phase voltage waveform and timesharing start-up control moment schematic diagram; Among the figure, abscissa is time t, and ordinate is three-phase voltage instantaneous value V.

Fig. 2 is that timesharing control starting drive structure is formed block diagram;

Fig. 3 is a bidirectional triode thyristor electronic switch schematic diagram;

Fig. 4 is an one-way SCR electronic switch schematic diagram;

Embodiment:

The present invention further specifies as follows in conjunction with specific embodiments referring to accompanying drawing:

A kind of threephase asynchronous timesharing startup method, it is a kind of startup method of controlling voltage, when threephase asynchronous starts, timesharing control three phase mains AC sine wave voltage puts on motor input terminals, referring to accompanying drawing 1, get any two-phase, for example A, B two-phase instantaneous voltage difference DELTA U in A, B, the C three-phase voltage _ABBe zero moment, t among the figure ₀Constantly, connect this two-phase voltage U _ABPut on A, the B two-phase input of the correspondence of motor, this is t constantly ₀, another phase voltage C disconnects motor, postpones behind a period of time Δ t when another phase C phase instantaneous voltage value is zero t among the figure ₁Constantly, just connect the C phase voltage, apply the C phase input of ground motor correspondence.

Of the present inventionly realize that referring to accompanying drawing 2, this device is electrically connected and formed by voltage sample and regulator rectifier circuit 1, single chip machine controlling circuit 2, electronic switch drive circuit 3, high-power electronic switch circuit 4 by a cover voltage timesharing control starting drive.Voltage sample and regulator rectifier circuit 1 input are received three phase mains and are carried out voltage sample, the voltage sampling signal of output is received single chip machine controlling circuit 2, and the dc constant voltage of voltage sample and regulator rectifier circuit output simultaneously is connected to single chip machine controlling circuit 2 respectively and electronic switch drive circuit 3 provides dc supply; Single chip machine controlling circuit 2 carries out voltage control according to voltage sampling signal, the output control signal is connected to electronic switch drive circuit 3, electronic switch drive circuit 3 sends the timesharing Continuity signal and is connected to high-power, electronic switching circuit 4, the three-phase gate-controlled switch branch road of high-power electronic switch 4 is connected on respectively in the three phase mains input circuit of three-phase AC asynchronous motor M, by above-mentioned threephase asynchronous timesharing startup method, the conducting of control three-phase voltage reaches the purpose that timesharing starts constantly.

High-power electronic switch circuit 4 can be by the high-power electronic device of two-way admittance, as bidirectional triode thyristor SCR ₁Connect and form, referring to accompanying drawing 3, also can be by the high-power electronic device of unidirectional conducting, as unidirectional controllable silicon S CR ₂Connect and form, referring to accompanying drawing 4.Also can form high-power electronic switch circuit 4. by other the high-power electronic device of unidirectional or two-way controlled conducting

The advantage of method of the present invention is to reduce starting current greatly under the prerequisite of the detent torque that guarantees that threephase asynchronous is enough, and starting current can be reduced to 1.6-1.8 times below the rated operational current.Thereby reducing threephase asynchronous starts to the impact of line voltage and to the influence of other power consumption equipments.

Claims

1, a kind of three-phase AC asynchronous motor timesharing startup method, it is a kind of startup method of controlling voltage, it is characterized in that it is when threephase asynchronous starts, timesharing control three phase mains AC sine wave voltage puts on motor input terminals, at A, B, appointing two-phase instantaneous voltage difference in the C three-phase voltage was zero moment, connect the corresponding two-phase input that this two-phase voltage puts on motor, this constantly, another phase voltage is disconnected motor, when delay a period of time to another phase voltage instantaneous value is zero, just connects another phase voltage and put on another corresponding input of motor.