Active Reset Circuit with Energy Recovery for Solid State Modulators

Summary form only given. In order to reduce pulse losses two active reset circuits are proposed in this paper. The first one is based on the passive reset circuit and offers the possibility´ to feed the excessive energy stored in the transformer/inductor partly back to the source instead of dissipating it. This leads to a reduction of the losses by 20-30% of the passive circuit and a significant improve of the efficiency. The second reset circuit is based on the topology presented, where the excessive energy is stored in an capacitor which is in series to the freewheeling diode. This energy is used to premagnetize the transformer core. In the paper a charging circuit which compensates for the losses is added to this topology. Furthermore, control strategies are presented which allow to keep the premagnetizing current constant for a certain period of time and which could be applied for using the remanence of the core for a pulse premagnetization. In this case the core is premagnetized with a current which is turned off after the premagnitization. In the paper detailed information on the waveforms and the design of the proposed topologies is given and the losses of the different topologies are compared.