Output frequency control method for brushless doubly-fed generator without position sensor

Abstract

The invention discloses an output frequency control method for a brushless doubly-fed generator without a position sensor. The output frequency control method does not rely on the position sensor, does not need to know parameters of a brushless doubly-fed generator, utilizes an acquired voltage of a power winding of the brushless doubly-fed generator to achieve identification of rotation speed, avoids a series of problems caused by the position sensor, and can effectively control output frequency of the brushless doubly-fed generator. When the brushless doubly-fed generator and an outer power grid need to be used in a grid-connected manner, the parallel operation process can be completed successfully without the position sensor. Since a brushless doubly-fed generation system needs to acquire the voltage of the power winding of the brushless doubly-fed generator to form a voltage closed loop so as to achieve effectively control on voltage amplitude output by the brushless doubly-fed generator, the output frequency control method can effectively reduce cost of the position sensor and a matched sampling circuit, and does not incur any additional cost on the basis.

Description

technical field [0001] The invention belongs to the technical field of AC motors and their control, and more specifically relates to a method for controlling the output frequency of a brushless doubly-fed generator without a position sensor. Background technique [0002] Brushless doubly-fed motors originated at the end of the 19th century and were developed from series pole induction motors. Since the brushless double-fed motor has the advantages of simple structure, reliable operation, and small capacity of the frequency converter, it has gradually become a research hotspot since the 1980s. There are two sets of windings with different pole pairs on the stator of the brushless doubly-fed motor, which are called power windings and control windings respectively. Among them, the frequency of the power winding is generally constant frequency, and the voltage is generally constant voltage. The voltage and frequency of the control winding need to vary according to the speed an...

AI Technical Summary

Problems solved by technology

[0004] However, in the traditional brushless double-fed generator control algorithm, it is necessary to rely on the position sensor or speed sensor installed at the end of the motor (hereinafter collectively referred to as the position sensor) to realize the control of the motor. The main disadvantages of using the position sensor are: ( 1) The reliability of the system is poor

First, the position sensor is easily damaged in a high temperature environment

For example, in the ship shaft power generation system, the brushless double-fed generator is generally placed at the bottom of the cabin. In summer, the local temperature of the cabin sometimes even exceeds 50 degrees. As high as 90 degrees, the heat is transferred to the position sensor along the connecting shaft of the rotor, which makes the temperature of the position sensor rise. Excessive temperature will seriously affect the service life of the position sensor

Secondly, the position sensor is always operating in a vibrating state, and it is easy to be damaged due to mechanical reasons when it is installed incorrectly.

(2) Increase the cost of the system and easily cause problems in electromagnetic compatibility

(3) Since the position sensor will increase the axial length of the motor, in some special occasions such as places where the space is extremely narrow, the system cannot be installed

The existing position sensorless control algorithm generally uses the mathematical model of the complex motor to identify the speed, so there is a problem of inaccurate identification

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