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• Time of issue:2022-10-24 17:05
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(Summary description)In recent years, people are paying more and more attention to safe travel and environmental protection, and the use of electric bicycles is increasing. The speed of traditional pure electric bicycles is regulated by the handlebar, which is based on open-loop control and is inadequate in terms of safety and comfort, while electric bicycles are powered by a power-assist system that detects the amount of pedaling force during cycling to control the output of the power-assist motor, thus achieving intelligent power-assist for the cycling state. As the core of the power-assisted bicycle, the power-assisted system is the key to the study of power-assisted bicycles, which mainly includes the torque sensor system and the power-assisted motor control system. Common torque sensor designs include torque displacement conversion, strain gauge detection and the use of inverse magnetostrictive effects. The design of the booster motor control system includes the design of the main control circuit and the implementation of the motor control algorithm. The main contents of this paper are as follows: (1) In the design of the torque sensor, firstly, several torque sensors in the domestic and international market are studied and compared, and then a crank torque sensor system based on strain gauge detection is proposed. The crank torque sensor is mainly composed of a full bridge of resistance strain gauges, an AD623 instrumentation amplifier and the crank mechanical structure. In order to improve the accuracy and stability of the crank torque sensor signal, Kalman filtering is used to filter the collected torque signal. (2) In the design of the booster motor control system, the design of the main control circuit, motor drive circuit and power supply detection circuit were completed first, and then the system software and algorithm design were completed. The TMS32f28027 32-bit DSP processor is used as the main control chip, and the inductorless BLDCM is used as the booster motor. Then, the inverse electric potential method is introduced to detect the rotor position of the booster motor, and the vector control algorithm is used to control the torque of the motor. (3) Finally, the whole power assist system was tested, including the construction of the experimental platform, the testing of the power detection circuit, the testing of the new crank shaft stress, the testing of the performance of the crank torque sensor and the testing of the output of the booster motor. The experimental results show that the power-assisted system works stably, measures the pedal force with high accuracy, and is capable of powering the electric-assisted bicycle.