A 1kW drive for an electric bicycle

Abstract

This dissertation involves the design, building and testing of a battery pack, power electronic circuitry, and the microcontroller and software based control circuit of a 1kW electric bicycle (e-bike). These drive components were designed to be assembled on, and to replace the components of an existing electric bicycle. The main objectives were to investigate possible design innovations in the current systems utilised in e-bikes and to construct a more flexible and upgradeable system that works to 1kW. The design objective for the battery was to achieve an architecture which allows and facilitates the replacing of individual cells without changing the battery housing, wiring and protection circuitry. This would enable servicing or upgrading the battery by tting more energy dense cells. A further aim was to design a reprogrammable, stand alone micrcocontroller based motor control board for the brushless DC motor (BLDC) used in the bicycle. This board processes inputs from the rider's application of throttle and brakes, and outputs driving signals to the power electronic circuitry. The innovative value for the user would be a control board that can be used with power electronic circuitry of di erent power ratings, and allows for upgrading and modi cation of the bicycle software for di erent uses, such as in quad bikes. The complete drive system was built and tested, and a closed loop current reference control algorithm was implemented in software. The bicycle motor was successfully driven by this control circuitry and the battery pack was tested under load.