AC frequency-conversion inductive brushless excitation system of synchronous motor

Abstract

The invention relates to an AC frequency-conversion inductive brushless excitation system of a synchronous motor. The system comprises a frequency-conversion excitation controller (1), an AC inductive exciter (2) and a rotary rectifier (3), the frequency-conversion excitation controller (1) provides AC, whose frequency and amplitude are adjustable, of a power supply to a stator inductive winding (5) of the AC inductive exciter, and the rotary rectifier (3) coverts inductive AC voltage of a rotor inductive winding (5) of the AC inductive exciter into DC to supply power to an excitation winding (6) of the synchronous motor. Brushless excitation of the synchronous motor and control for brushless excitation are realized. Compared with the prior art, the AC frequency-conversion inductive brushless excitation system can output sufficient excitation power at any operational rotating speed, detect the current, position and rotating speed of the rotor and start a power-frequency synchronous motor through the brushless excitation system; and the system can be widely applied to brushless excitation of the synchronous motor.

Description

technical field [0001] The invention relates to a brushless excitation system of a synchronous motor. Background technique [0002] The brushless synchronous motor generally uses an AC exciter to provide excitation power, and the brushless excitation of the main synchronous motor is realized through a rotating rectifier. The AC exciter is essentially a synchronous generator with armature rotation. The output excitation power is limited by the motor speed, the power density is not high, and the volume is large; and in the control of brushless excitation, the AC exciter is an inertial link. It affects the dynamic performance of excitation control. Using a rotating controllable rectifier can improve the dynamic performance of the excitation system, but it makes the rotor circuit complex and reduces its reliability. In addition to the above-mentioned problems, the brushless excitation system also has the following problems: First, the variable-frequency synchronous motors, inc...

AI Technical Summary

Problems solved by technology

The AC exciter is essentially a synchronous generator with armature rotation. The output excitation power is limited by the motor speed, the power density is not high, and the volume is large; and in the control of brushless excitation, the AC exciter is an inertial link. Affects the dynamic performance of the excitation control

The dynamic performance of the excitation system can be improved by using a rotating controllable rectifier, but the rotor circuit is complicated and the reliability is reduced

In addition to the above-mentioned problems, the brushless excitation system also has the following problems: First, the variable-frequency synchronous motors, including hybrid excitation synchronous motors with permanent magnet poles, require excitation at any operating speed, but AC exciters and harmonics The excitation power of the excitation output decreases with the decrease of the speed, and the output excitation power is obviously insufficient at low speed, especially when the speed is zero, there is no excitation power output; The brush excitation system must add a starting resistor and a thyristor automatic excitation device to the rotor, which makes the rotor circuit complex and reduces reliability, and the synchronous motor has a large current when it starts asynchronously, which will have an impact on the power grid

Images