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US 7,126,409 B2Granted
Three level inverter
AssigneeAmerican Power Conversion Corporation
InventorHenning Roar Nielsen
Life of this patent
Estimating the term…
Abstract
The present invention relates to a high efficiency three-level inverter apparatus containing both bipolar and field effect transistors. An embodiment of a modified control scheme is also presented whereby transistors are modulated differently for each quadrant of output voltage-current phase. This embodiment of a modified control scheme allows efficient switching of field effect transistors without additional freewheeling and series diodes.
Claims17
A three-level inverter comprising:
- an electrical output having a time-varying output voltage controlled by an inverter stage;
- the inverter stage comprising:
- a first and a second field effect transistor, each comprising a drain and a source;
- and
- a first and a second bipolar transistor in electrical communication with the first and the second field effect transistors, each comprising a collector and an emitter;
- wherein the time-varying output voltage comprises at least three substantially discrete voltage levels supplied by the inverter stage and is filtered by a filter stage comprising a second electrical output having a low-frequency AC voltage.
3 more elements
A method for controlling an output voltage of an inverter, the method comprising:
- modulating a first control signal coupled to a first transistor and a second control signal coupled to a second transistor when a polarity of voltage across a filter choke and a polarity of current through the filter choke are determined to be opposite;
- and
- holding the first control signal and the second control signal when the polarity of voltage across the filter choke and the polarity of current through the filter choke are determined to be the same.
A three-level inverter comprising:
- a first and a second field effect transistor;
- a first and a second bipolar transistor;
- wherein the field effect transistors and the bipolar transistors are in electrical communication to form a series path between a first voltage source and a second voltage source;
- and
- a control system in electrical communication with the field effect transistors and the bipolar transistors, wherein the control system is configured to provide control signals to the field effect transistors and the bipolar transistors and is configured to modulate the first and the second bipolar transistors in a substantially complementary manner.
2 more elements
A three-level inverter comprising:
- a first and a second field effect transistor;
- a first and a second bipolar transistor;
- wherein the field effect transistors and the bipolar transistors are in electrical communication to form a series path between a first voltage source and a second voltage source;
- and
- a control system in electrical communication with the field effect transistors and the bipolar transistors, wherein the control system is configured to provide control signals to the field effect transistors and the bipolar transistors and is configured to modulate the first and the second bipolar transistors in a substantially complementary manner while the three level inverter is determined to operate in an output phase quadrant characterized by an output current and an output voltage having opposite polarity.
2 more elements
A three-level inverter comprising:
- a first and a second field effect transistor;
- a first and a second bipolar transistor;
- wherein the field effect transistors and the bipolar transistors are in electrical communication to form a series path between a first voltage source and a second voltage source;
- and
- a control system in electrical communication with the field effect transistors and the bipolar transistors, wherein the control system is configured to provide control signals to the field effect transistors and the bipolar transistors and is configured to provide constant state control signals to the first and the second field effect transistors while the three level inverter is determined to operate in an output phase quadrant characterized by an output current and an output voltage having opposite polarity.
2 more elements
A three-level inverter comprising:
- a first and a second field effect transistor;
- a first and a second bipolar transistor;
- wherein the field effect transistors and the bipolar transistors are in electrical communication to form a series path between a first voltage source and a second voltage source;
- a control system in electrical communication with the field effect transistors and the bipolar transistors, wherein the control system is configured to provide control signals to the field effect transistors and the bipolar transistors;
- a first electrical output comprising a pulse-width modulated output voltage coupled to a point along the series path and having at least three substantially discrete voltage levels;
- and
- the first electrical output is filtered by a filter stage comprising a second electrical output having a low-frequency AC voltage and a filter choke having a time-varying current.
4 more elements
Dependencies are inferred from the claim text.