矿用无位置无刷直流风机转子位置检测研究

Research on the control system of mine-used high voltage sensorless brushless DC fan

为解决传统矿用通风机采用异步电机效率和功率因数低等问题,设计一种高压无位置传感器无刷直流矿用风机控制系统;改进传统高压无位置无刷直流电机控制系统在高速运行时反电势过高,而在低速运行时反电势过低,导致传统反电势过零检测电路不能正常工作,限制控制系统调速范围的问题。通过给传统电阻分压的三相反电势采样电路中并联三极管,根据矿用风机转速调节控制三极管斩波信号的导通时间,实现电机运行在高速时占空比线性增大,在低速时占空比线性减小,来控制比较器的输入电压在合理范围内,改善矿用风机在高低速运行时反电动势过零检测效果,从而提高控制系统效率及调速范围。设计的控制系统以低成本的微型控制芯片为核心,并且给出系统主要电路设计及主程序流程。该控制方案相较于传统控制方案具有成本低、体积小、易于使用等优点。实验结果表明设计的控制系统能够有效提高电机效率及准确检测反电动势过零点,保证电机在1%~100%的转速范围内稳定运行。

In order to solve the problems of low efficiency and low power factor of asynchronous motor used in traditional mine ventilator,a high-voltage sensorless brushless DC mine fan control system was designed.The traditional high-voltage sensorless brushless DC motor control system was improved when the back EMF was too high in high-speed operation,but too low in low-speed operation,resulting in the fact that the traditional back EMF zero crossing detection circuit could not work normally,which limited the speed range of the system.By paralleling the transistor in the three-phase back EMF sampling circuit of the traditional resistance voltage divider,the conduction time of the transistor chopping signal was adjusted and controlled according to the speed of the mine fan,so that the duty cycle of the motor was increased linearly at high speed,and was increased at low speed.Thus,the input voltage of the comparator was controlled within a reasonable range and the detection effect of back-EMF zero-crossing was improved when the mine fan was running at high and low speeds,thereby improving the efficiency of the control system and the speed adjustment range.The designed control system was based on a low-cost micro-control chip,and the main circuit design and main program flow of the system were made.Compared with the traditional control scheme,this control scheme has the advantages of low cost,small volume and easy to use.The experimental results show that the designed control system can effectively improve the efficiency of the motor and accurately detect the zero crossing point of the back EMF,thus ensuring the stable operation of the motor in the speed range of 1%~100%.