The Research Of Sensorless BLDC Motor Control System

The paper has studied the BLDCM sensorless control technology and designed a BLDCM sensorless control system based on MCU aiming for the existed problems, then proved the availability of the project through experiments.The paper introduced the background and the study status of this field firstly. By analyzing and synthesizing the existed research results, it presented a feasible project: the position detection of the rotor adopted the end voltage method based on the back electromotive force method, that is, by detecting the point crossing zero of the back electromotive force of the electromotor stator the changing information of the phase of the stator would be got; The start of sensorless BLDCM and the well-off switch from the out-synchronization to the in-synchronization by"three steps start"method. the control of the temperature used fuzzy control.The paper had studied the design of the system'hardware. On analyzing the need of the power hardware, the paper gived the circuit of +48V DC. Based on the BLDCM control theory and application, TMP88PH40 had been used as the core of micro-control circuit. The paper introduced the running of BLDCM controlled by TMP88PH40 in details. Based on the rotor position detection theory, The paper gived the design of the rotor position detection hardware. IR2103 was used in driver circuit. The paper introduced the setting of driver circuit's key parameters.The paper gived the diagram of the system control'software, especially introduced the position detection subroutine. Designed seven working status'functions, The BLDCM working controlled by theses functions, with the help of the hardware. The paper discussed why fuzzy control had been choosen for temperature controlling and how to control temperature. At last, the paper gived the waveforms obtained by experiments and analyzing. Results of theses experiments improved the availability of the project.