Energy Regeneration Based on Supercapacitor Direct Connection for Wound-Field Brushless DC Motors

An energy regeneration topology based on a directly connected supercapacitor (SC) is proposed for the wound-field brushless DC motor. During braking regeneration, the SC is directly connected to the DC-link of the wound-field brushless DC motor, with the DC-DC converter omitted, to absorb regenerated energy. After the braking state ends, the SC is connected to the input side of the field current converter. A double closed-loop energy regeneration control method based on proportional-integral-derivative (PID) controllers is established, along with a mathematical model for the reutilization of SC energy. An analytical model of field current (AMFC) based on the external characteristics of the doubly salient electromagnetic machine (DSEM) is proposed by calculating the reference value of the field current. Compared with the conventional PID controller, AMFC provides optimized performance with higher control precision and faster response speed. The energy regeneration experiments demonstrate that the AMFC controller exhibits better tracking performance to the conventional PID controller. The energy reutilization experiments validate the proposed mathematical model. By eliminating the DC-DC converter, the proposed topology offers an efficient, low-cost solution for energy regeneration and reutilization of DSEM applications for special vehicles.