Electronic control unit for BLDC motors in electric bicycles with 8-bit microcontroller

The aim of this paper is the scheming of an electronic control unit for BLDC motors in an electric bicycle, characterized by new solutions for the control method and the 8 bit microcontroller system. A dynamic model of the vehicle has been realized, and the characteristics of the ECU have been individuated. A basic electric bicycle runs on a brushless DC (BLDC) motor, is powered by batteries and controlled from an ECU. The BLDC motor for the electric bicycle is of the standard three phase trapezoidal type, typically rated at a few hundred watts and the battery voltage is usually 36V or 48V. Almost all the electronics in the electric bicycle are found in the ECU, it contains the inverter circuit for the motor; temperature sensor; fault detection; SMPS; analog and digital IOs; and finally the controller itself. Some ECUs have advanced features such as Remote Key Entry (RKE) and electric horn as well. All of these as well as the wiring packed into a metal box of typical dimensions 10x7x3 cm3. Most electric bicycle manufacturers prefer an inverter circuit designed with discrete components for cost consideration, this circuit takes up about half of the PCB leaving even less space for the rest of the circuit. This gives you an idea of the challenge facing the designers. From the MCU point of view, not only must it be functionally acceptable, it must be able to withstand the harsh environment within the box. The XC866 microcontroller has been used in this. An effective PWM control strategy has been studied, adjusting the motor torque and the current in order to increase the availability range. Finally, a feasibility study of a regenerative braking system based on the super capacitor technology has been carried out. All the components of the drive have been selected among the models available on the market. In this paper the results of the simulations are presented and other technical economical aspects such as energy consumption and costs are also briefly discussed.