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AssigneeGeneral Electric Company
InventorsRik W. A. A. De Doncker, James P. F. Lyons
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A method for controlling a power converter and an associated auxiliary commutation circuit ensures soft-switching of all switching devices employed therein. Such a power converter includes an inverter with at least two main switching devices per phase. Across each main switching device are connected an antiparallel diode and a relatively large snubber capacitor. The auxiliary resonant commutation circuit comprises two antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit including an inductor and the snubber capacitors. The gating and conduction times of the main and auxiliary switching devices are controlled so as to add boosting energy to the resonant operation, thus ensuring that the inverter output voltage at least reaches the positive and negative inverter rail voltages during each resonant commutation cycle. As a result, the control achieves commutation of the converter pole with substantially no switching losses.
A method for controlling a power converter of the type including an inverter having at least one phase, said inverter having at least two series-coupled main switching devices per phase, said series-coupled main switching devices being coupled to positive and negative rails of a dc supply, the junction between said main switching devices being coupled to a load, said main switching devices each having a snubber capacitor coupled in parallel therewith and an antiparallel diode coupled thereacross, said power converter further including a pair of series-coupled bus-splitting capacitors coupled between said positive and negative rails of said dc supply, said power converter further including an auxiliary resonant commutation circuit coupled between the junction joining said main switching devices and the junction joining said bus-splitting capacitors, said auxiliary resonant commutation circuit comprising a pair of antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit, said resonant circuit including an inductor and said snubber capacitors, said method comprising commutating load current between one of said main switching devices and the opposing one of said antiparallel diodes coupled across the other one of said main switching devices, when commutation is initiated with load current in said opposing one of said antiparallel diodes, by:
A method for controlling a power converter of the type including an inverter having at least one phase, said inverter having at least two series-coupled main switching devices per phase, said series-coupled main switching devices being coupled to positive and negative rails of a dc supply, the junction between said main switching devices being coupled to a load, said main switching devices each having a snubber capacitor coupled in parallel therewith and an antiparallel diode coupled thereacross, said power converter further including a pair of series-coupled bus-splitting capacitors coupled between said positive and negative rails of said dc supply, said power converter further including an auxiliary resonant commutation circuit coupled between the junction joining said main switching devices and the junction joining said bus-splitting capacitors, said auxiliary resonant commutation circuit comprising a pair of antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit, said resonant circuit including an inductor and said snubber capacitors, said method comprising commutating load current between one of said main switching devices and the opposing one of said antiparallel diodes coupled across the other one of said main switching devices, when commutation is initiated with load current in said one of said main switching devices, when the load current is less than a high current threshold, by:
A method for controlling a power converter of the type including an inverter having at least one phase, said inverter having at least two series-coupled main switching devices per phase, said series-coupled main switching devices being coupled to positive and negative rails of a dc supply, the junction between said main switching devices being coupled to a load, said main switching devices each having a snubber capacitor coupled in parallel therewith and an antiparallel diode coupled thereacross, said power converter further including a pair of series-coupled bus-splitting capacitors coupled between said positive and negative rails of said dc supply, said power converter further including an auxiliary resonant commutation circuit coupled between the junction joining said main switching devices and the junction joining said bus-splitting capacitors, said auxiliary resonant commutation circuit comprising a pair of antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit, said resonant circuit including an inductor and said snubber capacitors, said method comprising commutating load current between one of said main switching devices and the opposing one of said antiparallel diodes coupled across the other one of said main switching devices, when commutation is initiated with load current in said one of said main switching devices, when the load current is greater than a high current threshold, by:
A method for controlling a power converter of the type including an inverter having at least one phase, said inverter having at least two series-coupled main switching devices per phase, said series-coupled main switching devices being coupled to positive and negative rails of a dc supply, the junction between said main switching devices being coupled to a load, said main switching devices each having a snubber capacitor coupled in parallel therewith and an antiparallel diode coupled thereacross, said power converter further including a pair of series-coupled bus-splitting capacitors coupled between said positive and negative rails of said dc supply, said power converter further including an auxiliary resonant commutation circuit coupled between the junction joining said main switching devices and the junction joining said bus-splitting capacitors, said auxiliary resonant commutation circuit comprising a pair of antiparallel-coupled auxiliary switching devices coupled in series with a resonant circuit, said resonant circuit including an inductor and said snubber capacitors, said method comprising commutating load current between one of said main switching devices and the opposing one of said antiparallel diodes coupled across the other one of said main switching devices, when commutation is initiated with load current in said opposing one of said antiparallel diodes, when the load current is greater than a diode boost threshold, by:
Dependencies are inferred from the claim text.