Study On Sensorless Starting Control Of Brushless Synchronous Motor

With modern aircraft migrating to more electric and all electric architectures, starter/generatorsystem based on the brushless synchronous motor is highly appreciated. The mechanical positionsensor has some disadvantages, which provides rotor position for motor driver. In order to overcomethese shortcomings, the sensorless control technology has emerged and become the research focus ofthe starting control strategy for the brushless synchronous motor.Low speed sensorless control technology is the key to accomplish full speed sensorless control,attracting extensive attention of scholars. The fluctuating high frequency voltage injection method isstudied in this paper, and a novel method, which combines this method with the DC excitation on-offmethod, is proposed to estimate the initial rotor position. On that basis, the sensorless control fromstarting to low-speed operation is achieved.The mathematical model of the brushless synchronous motor is built and the principle of the vectorcontrol is analyzed. The performance of the starting control system is researched using Matlabsimulation software. Then, the principle of the fluctuating high frequency voltage injection isdiscussed, while the implementation of a novel initial rotor position estimation and low-speedsensorless operation is presented. The feasibility of the proposed scheme is demonstrated bysimulation results. Finally, a prototype platform of the sensorless starting control system is designedbased on DSP and CPLD. It is indicated by the experimental results that the rotor position during zerospeed and low speed could be estimated effectively with the proposed sensorless method, and thebrushless synchronous motor could start-up smoothly.