Double-feed motor adopting AC-DC-AC current transformer for speed regulation and its start control method

Abstract

The invention provides a double feed motor with an ac-dc-ac converter for speed control. The double feed motor adopts the ac-dc-ac converter instead of the conventional ac-ac converter, and designs a set of start scheme for stator-side short-circuit and rotor-side variable frequency combining the characteristic of the ac-dc-ac converter. The double feed motor combining the start scheme solves the problems in the prior art, effectively reduces the starting current of the motor, avoids the motor speed falling out of the regulating range of the converter during the switching process, simultaneously realizing starting with load.

Description

technical field [0001] The invention relates to a doubly-fed motor which adopts an AC-DC-AC converter to control the speed of the motor stator and rotor, and also relates to a start-up control method of the doubly-fed motor. Background technique [0002] With the development of power electronics technology, the doubly-fed speed control system composed of a converter composed of high-power semiconductor devices and a doubly-fed motor has received the attention of many people. Its main working principle is the stator and rotor three-phase The windings are respectively connected to two independent three-phase symmetrical power supplies. The power supply of the stator winding is a fixed-frequency industrial power supply, while the amplitude, frequency and phase of the rotor power supply voltage need to be adjusted separately according to the operation requirements. This speed regulation method has the advantages of adjustable power factor, high efficiency, small capacity of freq...

AI Technical Summary

Problems solved by technology

This starting method is simple and mature, but has some disadvantages: 1) The stator starts directly at zero speed, and the starting current impact is relatively large. 2) The rotor short-circuit switch is disconnected when the current is not zero, and the switch needs to provide a certain current breaking capacity; 3) The algorithm for re-introduction of the converter is more complicated, and the inrush current during input is relatively Big

This method has a small start-up inrush current, but the control process is complicated

In addition, due to the use of AC converters, the motor can only be dragged to 1 / 2 rated speed for grid-connected switching

If the motor has a large damping or load, the speed of the motor will drop rapidly during the switching process

And as long as there is a slight drop in the speed, the speed will exceed the speed regulation range of the AC converter, resulting in out-of-control grid-connected operation

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