Monopolar DC to bipolar to AC converter
View Patent ↗This invention improves the performance and lowers the cost of DC to AC inverters and the systems where these inverters are used. The performance enhancements are most valuable in renewable and distributed energy applications where high power conversion efficiencies are critical. The invention allows a variety of DC sources to provide power thru the inverter to the utility grid without a transformer and at very high power conversion efficiencies. The enabling technology is a novel inverter circuit topology where the DC source is connected directly to the positive bus of the DC to AC converter and where a negative bus is generated from the positive bus with a flyback converter. The inverter power topology does include or require a transformer. The AC inverter output configuration can be either single-phase or three-phase. The AC inverter output can be either utility interactive or directly supply loads.
1. A DC-to-AC power converter apparatus for converting power from a mono-polar DC source to an AC load where one side of said DC source is connected to the grounded, zero-voltage or neutral point of said AC load voltage, a point that is typically but not necessarily grounded with respect to earth and where said mono-polar DC source is connected directly across one of two DC buses and where a second DC bus of opposite polarity with respect to the first DC bus is created by an inverting DC-to-DC power converter where the mono-polar DC source is connected to the DC-to-DC converter input and the output of the DC-to-DC converter is connected to the second DC bus and where two semiconductor switching devices are connected in series across the two DC buses with the common point of the two semiconductor switching devices connecting through a filter inductor to an AC load, in a circuit arrangement typically know as a half-bridge, and where the DC-to-AC power conversion of one polarity of the AC waveform is accomplished with one power conversion stage and where the DC-to-AC power conversion of the opposite polarity of the AC waveform is accomplished with two power conversion stages.
2. A DC-to-AC power converter apparatus according to claim 1 having an additional half-bridge DC-to-AC converter section to drive split-phase loads.