Research And Design Of Six-Phase Asymmetrical Winding Brushless DC Motor Control System

Compared to the structure of the rotor and stator of traditional DC motor,the brushless DC motor(BLDCM)eliminated the brush and commutation,and the commutation function in DC motor is realized by using power electronic device.This structure eliminates the energy loss and equipment loss of the traditional DC motor in the commutation process with the advantages of large starting torque and wide speed range.The BLDCM also has wide motor efficiency range.Due to these characteristics,the BLDCM's applications and prospects are very broad.so the application of BLDCM and the prospects are very wide.Today,the pollution is pretty serious,the trend of electric vehicles to replace fuel vehicles is growing,The BLDCM will occupy a place in the field of electric vehicles with the advantages of high torque,high speed,high efficiency.The basic structure of BLDCM is introduced in detail in this paper,including the classification and characteristics of the stator and rotor.The basic working principle,the rotor position sensor,and commonly used devices of the BLDCM is expounded.Then taking the three phase BLDCM as an example,analysis the relationship between the vector direction of the six-phase asymmetrical BLDCM and the driving signal relative position respect position to the rotor.The mathematical model of BLDCM is established and the model is simplified to convenience the next simulation model.Current hysteresis control strategy is designed for the six-phase asymmetric BLDCM in the thesis.The advantages and disadvantages of the two hysteresis control strategies are analyzed.The principle and mathematical model of the hysteresis control strategy are importantly introduced.The model and the hysteresis loop control system of the six-phase asymmetric BLDCM is built by PLECS simulation.And the feasibility of the variable-loop hysteresis control strategy is verified by PLECS simulation.Hardware and software system are designed according to the hysteresis control strategy proposed in this paper.The hardware design the analog quantity detecting circuit and switch quantity detecting circuit,such as voltage,current,temperature and so on;The level conversion circuit of the driving signal enhances the driving voltage amplitude,increase the driving ability and anti-interference ability;The over-current protection circuit is designed to prevent the motor current exceeds the allowable value to occur fault.Control system debugging interface is designed using LABLVIE software,then achieve to save time and steps in the debugging period;Using the touch screen for data display,to achieve the application process of display and control purposes.In the design of software,DSP28335 control chip of TI and CPLD logic control chip are used together to design the hysteresis loop control system of six-phase asymmetrical BLDCM.Finally,the experimental platform is built,the controller is tested by torque measuring instrument,power analyzer and magnetic powder brake.The correctness of the control algorithm and the reliability of the hardware design are verified by analyzing the data and current waveforms.