Simple and robust feedback control of a two-switch multi-level half-bridge inverter with non-ideal operation

The THD+N performance of a novel multi-level half-bridge switching topology is presented. Experimentally implemented as a class-D audio amplifier featuring a low complexity, performance of the system using a simple type of error corrective voltage feedback is explored in the presence of abnormal operating conditions. Explored is the operation of the new topology in the presence of switch dead-time, and with discontinuous conduction in the windings of the coupled inductor which is specific to this topology. The resulting noise curves suggest that the feedback control investigated is sufficient to correct distortion introduced from discontinuous winding current and that switch dead-time does not noticeably impact the performance of the topology. In addition, analysis of the THD+N curves suggest the harmonic content introduced from the closed-loop controller itself is significantly better in the new topology, and that the new topology is capable of higher power output from less voltage lost to dead-time.