Power electronics controlled voltage source based on modified sigma-delta modulator

The paper presents a conception of power electronics inverter based on a modified sigma-delta modulator (SDM) in the inverter's control block. The proposed modulator includes the comparator with dynamic hysteresis instead of a latched comparator, being typically used in 1-bit SDMs. Thank to this feature a resolution of SDM output bit stream is, theoretically, unlimited. As result, value of THD of an inverter output voltage is essentially lower, compared to a typical SDM solution. This benefit is not paid by increase in the system complexity. Moreover, the control system is simpler than in a case of a conventional inverter. Due to very high frequency of a SDM output bit stream, in a power stage of inverter the gallium nitride (GaN) based E-HEMTs (E-HEMT: Enhancement mode High Speed Mobility Transistor) are implemented. However, in case of lower value of an inverter output power also Si based devices are still the right choice. In the paper the inverter control circuit basics, results of simulation experiments, and the design of voltage controlled voltage source (VCVS) for laboratory tests are presented.