Self-excitation mixed-excitation synchronous motor alternating current power-generating system and control method thereof

Abstract

The invention discloses a self-excitation mixed-excitation synchronous motor alternating current (AC) power-generating system and a control method thereof, belonging to a synchronous motor AC power-generating system. The power-generating system comprises a mixed-excitation synchronous motor, two current transformers, an excitation current detecting and regulating circuit, an output current detecting and regulating circuit, an output voltage detecting and regulating circuit, a rectifier bridge, a filtering capacitor and a digital voltage-regulating controller. The control method comprises three steps of control, i.e., voltage feedback control, load current feedback control and excitation current feedback control. The AC power-generating system does not need an external auxiliary power supply and can realize constant-voltage output within a wide rotating speed and large load range. The digital control leads to easy realization of parameter adjustment and modularization design. The AC power-generating system has an important application value in a constant-frequency or variable-frequency AC power-generating system of an airplane, a ship, an automobile, a wind power generation system and the like.

Description

technical field [0001] The invention relates to a self-excited hybrid excitation synchronous motor AC power generation system and a control method thereof, belonging to the technical field of synchronous motor AC power generation systems. Background technique [0002] According to different excitation sources, AC motors can be divided into two categories: electric excitation synchronous motors and permanent magnet synchronous motors. [0003] When the speed or load of the electrically excited AC synchronous motor changes, the DC excitation can be adjusted to easily achieve a stable voltage output, but the excitation power needs to be provided by an external power supply. The usual solution is to set a separate external power supply or use a three-stage motor structure. The use of external power supply requires additional power supply equipment such as batteries. In some cases, especially some small independent power supply systems, the system will be difficult to work witho...

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Problems solved by technology

The use of external power supply requires additional power supply equipment such as batteries. In some occasions, especially some small independent power supply systems, the system will be difficult to work without external additional power supply, which limits the application of power generation systems.

The three-stage electric excitation synchronous motor has been widely used in aviation and civil power systems. The motor adopts a three-stage brushless structure, including permanent magnet auxiliary exciter, exciter and main generator, permanent magnet auxiliary exciter output The excitation winding of the exciter is powered by the control unit, and the output of the exciter is rectified by the rotating rectifier on the rotor to provide excitation for the main generator. It can be seen that the motor system actually rotates coaxially with the main generator by adding two Generator, so as to provide excitation for the main generator. The motor structure, especially the rotor structure, is complex, and there is a rotating rectifier device on the rotor, which is not conducive to high-temperature and high-speed operation, and the reliability is low

However, once the permanent magnet synchronous generator is manufactured, the air-gap magnetic field is difficult to adjust, resulting in difficult adjustment of the output voltage. Therefore, it is difficult to achieve stable output voltage under the condition of changing speed and load, and it is difficult to demagnetize due to faults. It is difficult to apply to aviation, etc. main power system

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