Transformerless semiconductor AC switch having internal biasing means
First Claim
1. A transformerless AC semiconductor switch for coupling AC power to an AC load, comprising:
- first and second power input means for receiving power from an AC source;
first and second power output means for coupling AC power to a load;
first and second series connected MOSFETS having connected together first power terminals and second power terminals coupled between the first power input means and the first power output means, wherein the MOSFETS have connected together gate electrodes; and
internal voltage bias means coupled between the connected together first power terminals and the connected together gate electrodes of the MOSFETS for providing a gate voltage larger than the threshold voltage of at least one of the power MOSFETS, wherein the internal voltage bias means generates the bias from the first and second power input means without use of a transformer.
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Accused Products
Abstract
An improved semiconductor AC switch is described having internal bias generation for the power MOSFET switches and isolated control input. Dual power MOSFETS with substrate diodes are connected in series between source and load. DC gate bias for the MOSFETS is derived from an internal power supply containing energy storage which charges from the line, typically every half cycle. The gates of the power MOSFETS are tied to the internal bias generator through a voltage divider network containing a variable resistance controlled by an optical input signal. The internal energy storage may be a capacitor or solid state battery, preferably a monolithic thick or thin film battery. No transformers or external control bias generators are required and the resulting switch is particularly simple and compact.
45 Citations
20 Claims
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1. A transformerless AC semiconductor switch for coupling AC power to an AC load, comprising:
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first and second power input means for receiving power from an AC source; first and second power output means for coupling AC power to a load; first and second series connected MOSFETS having connected together first power terminals and second power terminals coupled between the first power input means and the first power output means, wherein the MOSFETS have connected together gate electrodes; and internal voltage bias means coupled between the connected together first power terminals and the connected together gate electrodes of the MOSFETS for providing a gate voltage larger than the threshold voltage of at least one of the power MOSFETS, wherein the internal voltage bias means generates the bias from the first and second power input means without use of a transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A transformerless AC semiconductor switch for coupling AC power to an AC load, and having internal biasing means, comprising:
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first and second power input means for accepting AC power; first power output means for coupling AC power to a load; first and second series opposed connected MOSFETS having coupled together first power terminals and second power terminals coupled, respectively, to the first power input and first power output means, wherein the MOSFETS have coupled together gate electrodes; and internal voltage bias means coupled between the coupled together first power terminals and the coupled together gate electrodes of the MOSFETS for providing a gate voltage larger than the threshold voltage of at least one of the power MOSFETS, wherein the voltage bias means comprises an integral energy storage means coupled to the first and second power input means for receiving energy therefrom during at least some half cycles of the AC power. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A transformerless AC semiconductor switch for coupling AC power to an AC load, and having internal energy storage means, comprising:
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first and second power input means for accepting AC power; first and second power output means for coupling AC power to a load; first and second MOSFETS having coupled together first power terminals and having a second power terminal of the first MOSFET coupled to the first power input means and having a second power terminal of the second MOSFET coupled to the first power output means and having coupled together gate electrodes; rectifying means having a first terminal coupled to the second power input means and a second terminal; energy storage means having a first terminal coupled to the second terminal of the rectifying means and a second terminal coupled to the coupled together first power terminals of the MOSFETS; and connection means extending from the first terminal of the energy storage means to the coupled together gate electrodes. - View Dependent Claims (18, 19, 20)
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Specification