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US 6,005,788 AGranted
Hybrid topology for multilevel power conversion
AssigneeWisconsin Alumni Research Foundation
InventorsThomas A. Lipo, Madhav D. Manjrekar
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AssigneeWisconsin Alumni Research Foundation
InventorsThomas A. Lipo, Madhav D. Manjrekar
Estimating the term…
The present invention provides a multilevel electric power converter including a plurality of DC voltage sources providing different DC source voltage levels. The DC source voltage levels are preferably multiples of each other and may vary in a binary fashion or in a geometric progression with a factor of three to provide a large number of output voltage levels for a given number of inverter levels. The multilevel inverter is preferably implemented as a series connected set of H-bridge inverters, with each H-bridge inverter having an independent DC voltage source providing the desired DC source voltage level. A hybrid modulation strategy may be employed whereby the lowest voltage level inverter is modulated at a high frequency, e.g., by pulse width modulation, and higher voltage level inverters in the multilevel inverter are modulated to provide a low frequency stepped waveform. The combined high frequency pulse width modulated and low frequency stepped waveform has good spectral quality. A high voltage high quality waveform may be generated in this manner by taking advantage of the high voltage blocking capability of switching devices, such as GTO thyristors, in the high voltage inverters in the multilevel inverter, and the high frequency switching characteristics of switching devices, such as IGBTs, in the lowest voltage level inverter in the multilevel inverter. A multilevel inverter in accordance with the present invention may be employed in a single-phase or multi-phase applications.
A multilevel electric power converter, comprising:
A multilevel electric power converter, comprising:
A method for providing a multilevel electric power converter output voltage signal, comprising the steps of:
A method for controlling a multilevel electric power converter to synthesize an AC voltage waveform on an output thereof, wherein the electric power converter includes a first inverter having a first DC voltage source providing a first DC source voltage level and first inverter switching devices connected across the first DC voltage source and responsive to first inverter switching device control signals, a second inverter connected in series with the first inverter and having a second DC voltage source providing a second DC source voltage level and second inverter switching devices connected across the second DC voltage source and responsive to second inverter switching device control signals, wherein the output of the electric power converter is connected to the first and second inverters, comprising the steps of:
Dependencies are inferred from the claim text.