A Dynamic Braking Control Strategy for DC-Excited Flux Switching Machine

Regenerative braking is the most popular method for braking energy recovery of drive motor in electric vehicles. Recovered energy can extend electric vehicle's traveling distance. This paper presents a braking control strategy for a de-excited flux switching machine which is designed to drive small electric scooters. Regenerated energy during motor braking is stored in a super capacitor. During braking period, the field winding and its driver is controlled such that the braking energy can charge the super capacitor, or the stored energy can be discharged back to the dc link. No addition inductor is required. The relationships between recovery energy, braking speed, deceleration rate, and load inertia are analyzed. The analysis considers all the losses in the motor and drive. The optimal deceleration rate for energy recovery is calculated and used for control. Experiments are performed to verify the proposed control strategy.