Impact Factors for Energy Reclamation Control of an Air-Core Pulsed Alternator

Abstract

Thermal management of air-core pulsed alternators is an important problem to be solved before the alternators come to eventual deployment in mobile applications. The stator thermal problem is mainly caused by the armature winding heat generation and the rotor thermal problem is mainly caused by the field winding heat generation. Unlike the stator thermal management study, there is little literature about the rotor thermal management. So, the rotor thermal management remains a major challenge because of the poor conductivity of rotor material. Therefore, an energy reclamation control strategy was presented in this paper to reduce the heat generation of the field winding after discharge process. In the energy reclamation process, the self-excitation bridge starts to work again making the pulsed alternator work as a motor and a portion of the electromagnetic energy stored in the field winding is converted to rotor kinetic energy. Because the heat loss is reduced, the efficiency of the whole system can be improved. The equivalent circuit topology that can realize the energy reclamation control was established. Based on the circuit topology, the factors impacted the energy reclamation efficiency were analyzed. The impact factors include not only control parameters but also design parameters of the alternator. Under some assumptions, the optimal trigger angle was calculated. Conclusions that can offer guidance for the design and optimization of air-core pulsed-alternator systems were also reached.