Improvement of BLDC Motor Efficiency at Low Speed Operation through Internal Wiring Configuration Switching

Nowadays, brushless direct current (BLDC) motors are widely used in transportation devices due to their light weight, to their reliability and durability, and also to their high efficiency. In this paper, a BLDC motor winding internal wiring configuration switching method is presented in order to achieve improved efficiency at the different torque-speed operating points. This method is particularly advantageous for low speed motor operation. The winding wiring is internally switched among different configurations, thus obtaining an equivalent coil with variable equivalent cross-section and number of turns. An experimental setup has been built with two identical machines mechanically coupled on the same shaft, the one with the original wiring configuration under generator or braking working regime, and the other with the proposed wiring configurations under motor working regime with its motor drive controller. Numerous tests have been performed under different controller setpoints and braking loads, satisfactorily achieving up to 30% motor power requirement reduction with respect to the original configuration.