Reducing Voltage Rating of Devices in a Multilevel Converter
AssigneeTexas Instruments Incorporated
InventorsChih-Wei Chen, Yogesh Kumar Ramadass
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Abstract
A method for operating a multi-level converter is disclosed. A multi-level converter is provided with a plurality of switches connected in series and a flying capacitor connected to switch nodes of the plurality of switches, The switch nodes are biased initially to a fraction of an input voltage when the input voltage is initially applied to the plurality of switches. The flying capacitor is then precharged to a flying capacitor operating voltage. The multi-level converter is then operated after the flying capacitor is precharged by activating control signals to the plurality of switches. Diversion of precharge current by the plurality of switches may be performed while the flying capacitor is being precharged.
Claims24
A multi-level converter comprising:
- a plurality of MOSFET switches connected in series with a switch terminal located among the plurality of MOSFET switches configured to provide an output voltage, in which an input voltage terminal is connected to a first one of the plurality of MOSFET switches and a return voltage terminal is connected to a last one of the plurality of MOSFET switches;
- a flying capacitor connected to switch nodes of the plurality of MOSFET switches;
- a precharge circuit coupled to the flying capacitor and configured to initially bias the switch nodes to a bias voltage equal to a fraction of the input voltage and then to precharge the flying capacitor to the bias voltage when an input voltage is initially applied to the input voltage terminal;
- and
- blocking circuitry comprising a first precharge switch coupled to a body terminal of a first MOSFET switch of the plurality of MOSFET switches and operable to prevent diversion of precharge current to the switch terminal by the first MOSFET switch while the flying capacitor is being precharged.
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A method for operating a multi-level converter, the method comprising:
- providing the multi-level converter having a plurality of MOSFET switches connected in series and a flying capacitor connected to switch nodes of the plurality of MOSFET switches;
- biasing the switch nodes initially to a fraction of an input voltage when the input voltage is initially applied to the plurality of MOSFET switches;
- precharging the flying capacitor to the bias voltage;
- blocking diversion of precharge current by at least a first MOSFET switch of the plurality of MOSFET switches while the flying capacitor is being precharged by using blocking circuitry having a first precharge switch coupled to a body terminal of the first MOSFET switch;
- and
- operating the multi-level converter after the flying capacitor is precharged by activating control signals to the plurality of MOSFET switches.
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Dependencies are inferred from the claim text.