Study On Control System Of In-wheel Motor Without Position Sensor Used For Electric Scooter

In the context of the worldwide population aging problem, electric scooter that facilitates the passage of life for elderly and disabled persons has got a great deal of concern in recent years. Caring for life of the elderly and disabled populations not only embodies modern civilization of mankind, but also is an important aspect of social harmony. Therefore, the development of simple structure, easy operation, safe-reliable and cost-effective electric scooter has an important practical significance and market prospects.This paper has studied the core component of electric scooter– in-wheel motor controller, and discussed methods of design and implementation. Integral control mode with lower cost was carried out by combination of structural characteristics of the mechanical system. Through drawing the development experience of existing control technology on electric scooter, the paper designed a safe, stable and easy-operating motor control system. The main contents are as follows:①As BEMF waveform of in-wheel motor without position sensor was too weak to detect signal at low speed, the paper adopted the "three-stage" starting method and conducted an in-depth analysis on its rotor position, acceleration and the conversion from external synchronization to synchronization.②The paper carried out analysis of BEMF method and studied of the voltage zero-crossing detection method in detail. Combined with the control system, the voltage zero-crossing detection circuit was not only designed, and the rotor position error was but also analyzed in order to compensate for it in software.③Designed function module circuits for in-wheel motor without position sensor control system based on dsPIC30F, including: power module circuit, power inverter module circuit, power driving circuit module, BEMF zero- crossing detection module circuit, protection module circuit for motor, angle sensor interface circuits, keys and the LCD module circuit, etc.. Anti-interference technology for PCB was also introduced.④The control system was optimized by proportional - integral - derivative algorithm. Software was completed and a number of debugging tests were conducted based on MPLAB IDE, C30, and MCD2.The paper has done a large number of studies on cost-effective in-wheel motor control system. The fact with full rigorous theoretical analysis and practical application background results in some reference value in engineering. It is important to own independent intellectual property rights to lay a good foundation for the follow-up study on electric scooter.