Minimizing torque ripple and copper losses in variable speed brushless DC motor

Copper losses have always been a problem in design and implementation of electric machines. The appearance of electrical vehicles and unavailability of reliable mobile energy sources in recent years have put more stress on this fact. In this paper, simple mathematical approach using differential calculus has been used to find optimum set of currents in a brushless DC motor for copper loss minimization. Equations are used to form a model and the equivalent SIMULINK model. Simulation results show that optimization of current signals on this model minimize the copper losses by almost 10 %. Due to its simplicity, this approach is less computationally expensive.