| Brushless DC motor has overload,high efficiency and many advantages as well as ordinary DC motor,and compared with AC motor,its structure is simple maintenance and so on.In the view of the above of Brushless DC motor,people start to use it,most of which use brushless DC motor with position sensor.By its application in the practice,it was found the position of output signal will be affected when the brush DC motor with position sensor work.under high temperature,humidity,and other harsh environment.In this case,the research and design of the control system of the brushless DC motor without position sensor is presented.In this thesis,it takes three-phase brushless DC motor as the carrier to study.Firstly,the thesis introduces it development situation at home and abroad,and necessity of research on it,analyzing its basic structure and workings,through the comparison of different ways,identified two and two conduction mode.According to the theoretical model is established,and the effect of different modulation modes on the non-conduction phase is studied.For the problem of starting and commutation of the brushless DC motor without position sensor,the starting method and the terminal voltage detection method are respectively adopted by the research and analysis.Secondly,in the theoretical analysis basic and MATLAB/Simulink simulation platform,the double closed-loop control system is built.As to the common brmshless DC motor torque ripple,the predictive current strategy is used in the thesis.Finally,after verified by simulation the feasibility of Brushless DC motor-without position sensor,the back EMF acquisition and zero output circuit,the current sampling circuit,PWM circuit,communication circuit are designed.The main control chip is 28335DSP in software.According to the software flow chart designed the program.In the experiment,the starting current and high speed current ware observed with oscilloscope.The feasibility of this method is explained by the analysis of the waveforms. |
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