Study And Design On Electric-Bike Controller Based On BLDCM

In the recent years,the motorbike has rapidly developed with the improving of living Chinese people. Because of air pollution of internal combustion engine,the local governments of different cities in China come on a lot of rules of law to restrict the use of combustion engine and then to promote the environment protection. So the green transportation has become, important issue. Electric-bike has been broadly adopted as complementation for public traffic in big cities, for its convenience and rapidness. Besides, electric-bike has zero release and low noise, helpful to environment protection and peaceful life. It deserves recommendation. And Brushless DC Motor (BLDC Motor) is largely used for Electric-bike driving, as it is simple to control, highly reliable and provides high output toque.In this project, ST7MC1K2 - an ST7MC-series MCU product of ST company has been used. The consideration between low-cost and good-controlling performance has been well balanced by choosing this central-controlling unit. The following works have been presented in this project.Firstly, the developmental trend of electric-bike is discussed, the reasons that BLDC motor largely used in electric-bike driving are explained, and controlling means of sensor and sensorless BLDCM are discussed, too.Furthermore, the controlling strategy has been designed in detail based on the characteristic of ST7MC MCU. This part includes the following works: User the BEMF zero-crossing detecte the rotor posotion;The current is measured indirectly by using a shunt- resistor;To the measurement of the velocity, a hardware-softening method has been adopted and calculate from the rotor posotion information;In order to guarantee the velocity modulation's precision and quick-response, a double closed-loop control for current and velocity has been adopted;And the motor's soft-starting method has been designed,make the electric-bike startup facilely at diffierent load.Moreover, the whole system's hardware and software have been designed based on the system's control strategy and the software reliable-designing question has been discussed in the paper.Finally, debug the control system and analyze the results. It indicates that the controller works effectively.The controller's reliable-designing question has also been discussed in the end.From the work which has been done in this project, the conclusion can be draw that the electric-bike control system based on the ST7MC MCU not only has the virtues of high-performance,high-reliability,but also has the automorphism startup,cruise function; easy to further developing.This paper presented an experimental base for the further research.