Control System Design, Dsp-based Position Sensorless Bldcm Drive

A method for simplified free-wheeling diode is proposed in this paper, which is based on the method for traditional free-wheeling diode. The author makes further research and finds that there are more serious questions for the free-wheeling diode method. To solve them the paper proposes an improved method, and makes comprehensive theory analysis, simulation and experiment research. In addition, design, manufacture and debug for a driver and control system of sensorless BLDCM are completed, which is base on TMS320LF2407A and improved free-wheeling diode method.The paper builds trapezoidal BLDCM model in view of sinusoidal BLDCM model in PSpice library. The model not only adapts for trapezoidal BLDCM's simulation less than 120° in width, but also implements high voltage bootstrap drive, which provides effective way for the analysis of bootstrap circuit, static, and dynamic performance.The paper makes deeply theory analysis for traditional free-wheeling diode method, finding that this method has some questions of the complex control algorithm and hardware detection circuit for the traditional detection method. In the first-phase research, to solve these questions the paper proposes a simplified free-wheeling diode method, and then makes simulation and experiment study, finding that the influence of "open phase" terminal voltage oscillation at PWM OFF on detection precision is heavy and the detection error is larger because of ignoring forward dropout of the free-wheeling diode. The author makes thorough theory, simulation and experiment study, and then proposes an improved detection method, which solves the detection error of neglecting free-wheeling diode dropout by terminal voltage offset, and effectively improves the influence of the "open phase" terminal voltage oscillation on position detection by synchronous sample skill.The paper proposes the question of "open phase" terminal voltage oscillation that influences the position detection precision of simplified free-wheeling diode method and improved free-wheeling diode method, then makes thorough theory analysis and simulation, experiment study, which suggest that improved scheme's accuracy and reliability is better than the simplified, and the former extends the frequency width ofpower devices.The author makes demo board for TMS320LF2407A, and completes the design, manufacture and debug of driver and control system of sensorless BLDCM; the system is composed of TI's DSP TMS320LF2407A, IR's diver IR2133 and improved free-wheeling diode method. The experiment suggests that this system can start smoothly, and wok in sensorless mode very well.