Studies On Control System Of Brushless DC Motor In HVDC Aircraft Power Supply

Respond to the requirement of an aviation department, the speed control techniques and the relative appliance techniques of rare earth permanent magnet brushless DC motor (BLDCM), which works for the new high-voltage power supply system of plane, is researched in this paper.The paper mainly includes three parts.First, base on the comprehensive analysis and study about the structure, principles and control rules of BLDC motor control system, its control method that used for HVDC system is researched. In order torealize the motor' s "soft start" ----an ideal start procession, asoftware program and a strategy of speed and current double close-loop control system are introduced to limit its start current. At the same time the speed close-loop system are simulated.Second, depend on the study of the principles and techniques of the miniature high-frequency single-ended fly-back switching power supply, especially the principles of the single control chip of switching powersupply----TOP224Y, and the calculation and design of high-frequencytransformer ,a switching power supply whose control chip is TOP224Y, is designed which accomplish the power transformation from 270V DCto 5VDC and 15VDC. In the meaning time, the problem of EMC is researched, and some methods to reduce the influences of EMC are put forward.Last, base on all those researches above, a controller, which usethe micro-controller chip----AT89C51, is designed. It uses the signalsthat come from the rotor position sensor to get the motor' s speed indirectly, and uses software to accomplish the signals of PWM wave and the strategy of speed close-loop control. The simulation about the control theory is verified by the experiment.This controller guarantees the motor works in 4 kinds of patterns safely, and the work's stability is ensured through several kinds of anti-disturbance techniques. The experiment results shows that: the swi tching power supply provide a perfect quality power for the controller; the motor's speed can be stabilized or adjusted incessantly in 4-kindof work patterns.