Three-phase inverter for small high speed motors
First Claim
1. A power inverter for generating an alternating current signal at two or more output terminals relative to a neutral terminal, from a direct current signal at a power terminal relative to a ground terminal, comprisingat least four transformers each having a primary winding and a secondary winding, the primary windings of the four transformers being connected in series in a transformer ring, pairs of the secondary windings being connected in series between the neutral terminal and a respective one of the output terminals, the turns ratio between the primary and secondary winding on a first transformer being different from the turns ratio between the primary and secondary winding on a second transformer,at least four switching circuits each connected to a node between a respective pair of the primary windings in the transformer ring, the switching circuits alternately connecting the nodes to which they are connected to the power terminal and the ground terminal in response to control signals.
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Accused Products
Abstract
A three-phase inverter for small, high speed motors such as a miniature centrifical compressor which has a low voltage, high current requirement. The inverter is supplied with DC power at 28 volts, and produces power of about 50 to 500 watts at about 15 volts, and at frequencies of about 5 to 9 kilohertz. Six D-type flip-flops with clock inputs produce twelve signals which are provided to six bridge drivers. Each bridge driver controls two MOSFET'"'"'s in series. The MOSFET'"'"'s are supplied with DC power. Outputs are fed to primaries of adjacent transformers in a circular array. The transformer secondaries are arranged in a star configuration to produce stepped voltage and saw-tooth current output wave forms approximating sinusoids in three phases.
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Citations
46 Claims
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1. A power inverter for generating an alternating current signal at two or more output terminals relative to a neutral terminal, from a direct current signal at a power terminal relative to a ground terminal, comprising
at least four transformers each having a primary winding and a secondary winding, the primary windings of the four transformers being connected in series in a transformer ring, pairs of the secondary windings being connected in series between the neutral terminal and a respective one of the output terminals, the turns ratio between the primary and secondary winding on a first transformer being different from the turns ratio between the primary and secondary winding on a second transformer, at least four switching circuits each connected to a node between a respective pair of the primary windings in the transformer ring, the switching circuits alternately connecting the nodes to which they are connected to the power terminal and the ground terminal in response to control signals.
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13. A method for generating an alternating current signal at two or more output terminals relative to a neutral terminal, from a direct current signal at a power terminal relative to a ground terminal, comprising
providing at least four transformers each having a primary winding and a secondary winding, the turns ratio between the primary and secondary winding on a first transformer being different from the turns ratio between the primary and secondary winding on a second transformer, connecting the primary windings of the four transformers in series in a transformer ring, connecting pairs of the secondary windings in series between the neutral terminal and a respective one of the output terminals, connecting a switching circuit to each node between a respective pair of the primary windings in the transformer ring, controlling the switching circuits to alternately connect the nodes to which they are connected to the power terminal and the ground terminal.
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25. A power inverter for generating an alternating current signal at two or more output terminals relative to a neutral terminal, from a direct current signal at a power terminal relative to a ground terminal, comprising
at least four transformers including transformers with larger cores and transformers with smaller cores, each transformer having a primary winding and a secondary winding, the primary windings of the four transformers being connected in series in a transformer ring, pairs of the secondary windings being connected in series between the neutral terminal and a respective one of the output terminals, at least four switching circuits each connected to a node between a respective pair of the primary windings in the transformer ring, the switching circuits alternately connecting the nodes to which they are connected to the power terminal and the ground terminal in response to control signals.
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36. A method for generating an alternating current signal at two or more output terminals relative to a neutral terminal, from a direct current signal at a power terminal relative to a ground terminal, comprising
providing at least four transformers including transformers with larger cores and transformers with smaller cores, each having a primary winding and a secondary winding, connecting the primary windings of the four transformers in series in a transformer ring, connecting pairs of the secondary windings in series between the neutral terminal and a respective one of the output terminals, connecting a switching circuit to each node between a respective pair of the primary windings in the transformer ring, controlling the switching circuits to alternately connect the nodes to which they are connected to the power terminal and the ground terminal.
Specification