Optimization of the energy consumption of the electric drive for a postal delivery bicycle

The optimization of the energy consumption of a power-on-demand system, used for the electric drive for a postal delivery bicycle, is discussed. Postmen tend to minimize their own contribution to the total traction power in case of a power-on-demand system. The optimization principle links the maximal allowable armature current of the d.c. motor to the armature voltage. This optimization principle was implemented on prototype controller and validated on the road. An important reduction of energy consumption of about 30% was obtained. This solution allows encouraging the cyclist to deliver more biomechanical power as the contribution of the motor to the total traction power is reduced with increasing vehicle speed. However, at start the maximal traction force of the motor is still available and thus still allows lowering the physical stress on the postmen.