A controlled rectification method for automotive brushless DC generator with ultracapacitor energy storage

Hybrid excitation brushless DC generator (BLDCG) and ultracapacitor are very promising in automotive integrated starter/generator (ISG) application. However, with a traditional diode rectification, it is difficult to regulate the DC-link voltage of BLDCG over a wide operating range at low cost. A controlled rectification method is proposed to improve generating capacity of BLDCG with ultracapacitor energy storage at low speed, winding energy storage can be transferred to DC-link bus, and thus DC-link voltage can be boosted to the required value. Steady state performance in continuous and discontinuous conduction mode is analyzed. Simulation and experiment results with ultracapacitor and load resistor prove the effectiveness of the controlled rectification method.