Active DC-power filters for switched reluctance drives during single-pulse operation

Switched reluctance machines (SRMs) receive increased attention because of their robust structure and their cost efficiency. However, one drawback of SRMs is the comparatively large dc-link capacitance needed to passively filter the current ripple caused by the high amount of magnetization energy oscillating between the dc-link capacitor and the machine. A large dc-link capacitance increases the size, weight and cost of the SRM inverter compared to inverters for conventional three-phase drives based on induction machines or synchronous machines. This thesis proposes the application of an active dc-power filter to minimize the dc-link capacitance of switched reluctance drives. One goal of this thesis is to evaluate the different filter technologies. For this purpose, not only the performance of the filters but also their impact on the overall drive system has to be considered. An important performance indicator is the system efficiency. To enable a thorough assessment of the active dc-power filter in the drive system, a new approach for SRM iron loss modeling is proposed. The approach is validated by a novel method based on bidirectional SRM phase currents. The results of this research are relevant to applications with high-speed SRMs. Part of the work has been applied to switched reluctance generators of range extenders for (series hybrid) electric vehicles. All results are based on detailed simulations and are validated by measurements on a high-speed test bench for electrical drives