Topological structure and device of three-stage brushless starting/generator three-phase alternating-current excitation system

Abstract

The invention relates to a topological structure and a device of a three-stage brushless starting / generator three-phase alternating-current excitation system. According to the topological structure and the device, a three-phase bidirectional inverter works in an inversion state and provides a three-phase alternating-current excitation current for an exciter during the starting and low-speed running phases of a motor by virtue of the characteristic of power bidirectional flowing of the three-phase bidirectional inverter, and the three-phase bidirectional inverter works in a rectification state, cooperates with another three-phase inverter to realize alternating current-direct current-alternating current conversion and then provides an excitation current for the exciter during the generating running phase of a generator. The method disclosed by the invention has the following beneficial effects that: the three-phase bidirectional inverter adopted in the method disclosed by the invention is used as a power converter in both the starting and generating processes of the main generator, and high in utilization rate; an excitation mode control method adopted in the method disclosed by the invention is capable of realizing alternating current-direct current-alternating current conversion, and capable of meeting the needs of the main generator on the excitation current under the different running modes.

Description

Technical field [0001] The invention belongs to the technical field of aviation AC motors, and specifically relates to a topological structure and device of a three-stage brushless starter / generator three-phase AC excitation system. Background technique [0002] With the rapid development of large aircraft technology, a high-voltage and wide-frequency variable frequency power generation system with integrated starting / generation functions is an important development direction for future aviation AC power systems. At present, most aircraft AC power systems in my country use three-stage brushless synchronous motors (see the block diagram figure 1 ) As a generator, this type of generator does not have the function of starting aero engines, and the engine is started by an independent starter. Such an engine-power system includes two sets of motors, which makes it larger in size and weight, complex in the system, and reduced in reliability. If the original three-stage brushless synch...

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Problems solved by technology

The motor is mainly designed to meet the power generation function, and there are the following problems in the motoring state: 1) In the static and low-speed state, the output voltage of the exciter is low, and the excitation current of the main generator is small, which seriously affects the on-load starting ability of the main generator ; 2) As the motor speed increases, the output voltage of the exciter increases gradually, and the excitation current of the main generator also gradually increases, that is, the excitation current of the main generator is always changing during the motor starting process

Scheme 1 can provide a larger excitation current during the static and low-speed phases of the main generator, but with the development of aviation power supply technology and the need for higher starting torque of the engine, the single-phase AC excitation method has been unable to meet the requirements of the main generator during the starting phase. Field Current Requirements

In scheme 2, the excitation mode of the exciter needs to be switched according to the different operating modes of the main generator. Since the power generation operation of the main generator is a long-time working mode, the stator winding of the exciter needs to increase the number of series turns per pole to reduce the stator winding of the exciter. The required DC excitation current, but the excessively high number of turns causes the exciter to have high impedance characteristics during the starting phase of the main generator, which requires a high input capacity for the stator winding of the exciter, and this scheme has requirements for the body of the exciter and the design of the excitation system higher

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