Double grid-connected switch three-phase phase-locked frequency conversion integrated machine and phase-locked method

Abstract

Double grid-connected switch three-phase phase-locked frequency conversion integrated machine and phase-locked method. The integrated machine is composed of a main circuit and a control circuit. The main circuit is composed of a frequency converter, four vacuum contactors, two voltage Hall sensors and a motor. The circuit is composed of four intermediate relays, PLC and control switch; when the system is working, the frequency converter completes the start-up process and the phase-locking of its output voltage to the grid voltage, and the PLC completes the switch control of the vacuum contact by controlling the action of the intermediate relay , so as to realize the power supply to the motor by the frequency converter at start-up, and the function of power supply to the motor by the power grid after the switching of the phase-locked and vacuum contactors is completed in the steady state; the present invention adopts three-phase phase-locked technology to phase-lock the voltage of the power grid, and adopts PI control The inverter locks the phase of the power grid and the output voltage phase of the inverter; it ensures that the voltage phases of the two are consistent when the power switching process occurs.

Description

Technical field[0001]The present invention relates to a motor drag apparatus, and more particularly to a double-parallel network switch triangular lock phase variable integrated machine and a phase-locked method.Background technique[0002]As my country's coal enterprises have improved the safety of production equipment, more and more mining motor enterprises consider designing inverters and motors as integrating, and integrated machines are increasingly welcomed by the market.[0003]Traditional one machine is only mechanically assembled in the frequency converter, PLC, relays and motors, simplifies the difficulty of the equipment to a certain extent, and improves the security of the drag system. However, in the actual production process, some motors have long been working on rated voltages and rated speeds, and there is no need for inverters to do too much control. If this time, the motor's power supply is changed from the inverter to a sinusoidal power grid, then the motor The reliab...

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Problems solved by technology

However, under rated working conditions, although the frequency and amplitude of the voltage output by the inverter are relatively close to those of the power grid, they cannot be guaranteed to be in the same phase. If switching is performed directly, a large inrush current may be generated, which will cause a huge impact on the motor and the power grid.

[0004] In addition, in order to realize the power switching function of the traditional all-in-one machine, the phase sequence of the power grid when the motor is rotating forward is first tested during installation, and the motor can only complete the switching of the power supply when the motor is rotating forward. This feature makes it It is greatly limited in the use of fault tolerance and freedom

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