Energy efficient voltage snubber circuit
First Claim
1. A snubber circuit for use in a power converting circuit including an input for coupling to a source of power and an output for coupling to a load to which converted power is to be delivered, the power converting circuit further including at least one power semiconductor switching device coupled between the input and the output of the converting circuit, said switching device being turned on and off to selectively conduct current through the power converting circuit, said snubber circuit comprising:
- capacitance means, coupled across the switching device, for charging with current bypassing the switching device when the switching device is turned off;
a voltage transformer having a primary winding and a secondary winding, said primary winding being coupled in series with said capacitance means to conduct a flow of current discharged by said capacitance means when the switching device is turned on;
inductance means, coupled in series with said secondary winding of said transformer, for forming a resonant circuit with said capacitance means to regulate the flow of discharge current from said capacitance means; and
circuit means, coupled to the power converting circuit input and said inductance means, for conducting the current flowing through said inductance means and said secondary winding of said snubber circuit, and returning energy stored in said capacitance means to the power source;
so that energy stored in said capacitance means is transferred to the power source through said transformer and said inductance means at a rate determined by said resonant circuit when the switching device is turned on.
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Accused Products
Abstract
A snubber circuit for use with a power seimconductor switching device of a power converting circuit. The snubber circuit includes a snubber capacitor, coupled across the switching device for charging with current bypassing the switching device when the switching device is turned off. The snubber circuit also includes a transformer having a primary winding coupled in series with the snubber capacitor to conduct the flow of current discharged by the snubber capacitor when the switching device is turned on. The snubber circuit further includes an inductor, coupled in series with a secondary winding of the transformer, for regulating the flow of discharged current from the capacitor. The snubber circuit is coupled to return the energy discharged from the snubber capacitor to a power source to which the power converting circuit is coupled.
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Citations
34 Claims
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1. A snubber circuit for use in a power converting circuit including an input for coupling to a source of power and an output for coupling to a load to which converted power is to be delivered, the power converting circuit further including at least one power semiconductor switching device coupled between the input and the output of the converting circuit, said switching device being turned on and off to selectively conduct current through the power converting circuit, said snubber circuit comprising:
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capacitance means, coupled across the switching device, for charging with current bypassing the switching device when the switching device is turned off; a voltage transformer having a primary winding and a secondary winding, said primary winding being coupled in series with said capacitance means to conduct a flow of current discharged by said capacitance means when the switching device is turned on; inductance means, coupled in series with said secondary winding of said transformer, for forming a resonant circuit with said capacitance means to regulate the flow of discharge current from said capacitance means; and circuit means, coupled to the power converting circuit input and said inductance means, for conducting the current flowing through said inductance means and said secondary winding of said snubber circuit, and returning energy stored in said capacitance means to the power source; so that energy stored in said capacitance means is transferred to the power source through said transformer and said inductance means at a rate determined by said resonant circuit when the switching device is turned on. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A snubber circuit for use in a power converting circuit including an input for coupling to a source of power and an output for coupling to a load to which converted power is to be delivered, the power converting circuit further including at least one power semiconductor switching device having a first terminal coupled to the input of the converting circuit and a second terminal coupled to the output of the converting circuit, said switching device being turned on and off to selectively conduct current through the power converting circuit, said snubber circuit comprising:
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a capacitor for charging with current bypassing the switching device when the switching device is turned off; a voltage transformer having a primary winding and a secondary winding; said capacitor coupled in series combination with said transformer primary winding, said series combination being coupled across said first and second terminals of said switching device, so that said primary winding conducts a flow of current discharged from said capacitor when the switching device is turned on; an inductor, coupled in series with said secondary winding of said transformer, for forming a resonant circuit with said capacitor to regulate the flow of discharge current from said capacitor when the switching device is turned on; and circuit means, coupled to the power converting circuit input and said inductor, for conducting the current flowing through said inductor and said secondary winding of said snubber circuit, and returning energy stored in said capacitor to the power source; so that energy stored in said capacitor is transferred to the power source through said transformer and said inductor at a rate determined by said resonant circuit when the switching device is turned on. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A power converting circuit, comprising:
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an input for coupling to a source of power; an output for coupling to a load to which converted power is to be delivered; at least one power semiconductor switching device coupled between said input and said output of said power converting circuit, said switching device being turned on and off to selectively conduct current through the power converting circuit; and snubber means, coupled to said switching device, for limiting a voltage change rate across said switching device when said switching device is turned off; said snubber means comprising; capacitance means, coupled across said switching device, for charging with current bypassing said switching device when said switching device is turned off; a voltage transformer having a primary winding and a secondary winding, said primary winding being coupled in series with said capacitance means to conduct a flow of current discharged by said capacitance means when said switching device is turned on; inductance means, coupled in series with said secondary winding of said transformer, for forming a resonant circuit with said capacitance means to regulate the flow of discharge current from said capacitance means; and circuit means, coupled to the power converting circuit input and said inductance means for conducting the current flowing through said inductance means and said secondary winding of said snubber circuit, and returning energy stored in said capacitance means to the power source. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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33. A three-phase AC-to-AC power converting circuit, comprising:
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rectifier circuit means, having an input for coupling to a three-phase AC voltage source, for rectifying the three-phase voltage of the AC source and providing a DC output voltage; filter circuit means, coupled to receive the DC output voltage of said rectifier circuit means, for filtering the DC output voltage and providing on a filter output a filtered DC output voltage, said filter circuit means including at least one filter capacitor; three-phase inverter circuit means, coupled to receive the filtered DC output voltage, for providing a three-phase AC output voltage on a three-phase AC output; said inverter circuit means including three inverter pole circuits having respective inverter pole outputs that together form the three-phase AC output; each said inverter pole circuit including at least one power semiconductor switching device coupled between the filter output and the inverter pole output, said switching devices of said respective inverter pole circuits being selectively turned on and off to convert the filtered DC output voltage to said three-phase Ac output, and snubber means, coupled to said switching device, for limiting a voltage change rate across said switching device when said switching device is turned off; said snubber means comprising capacitance means, coupled across said switching device, for charging with current bypassing said switching device when said switching device is turned off; a voltage transformer having a primary winding and a secondary winding, said primary winding being coupled in series with said capacitance means to conduct a flow of current discharged by said capacitance means when said switching device is turned on; inductance means, coupled in series with said secondary winding of said transformer, for forming a resonant circuit with said capacitance means to regulate the flow of discharge current from said capacitance means; and circuit means for conducting current flowing through said inductance means and said secondary winding of said snubber means to said filter capacitor; so that energy stored in said capacitance means is transferred to said filter capacitor through said transformer and said inductance means at a rate determined by said resonant circuit when said switching device is turned on. - View Dependent Claims (34)
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Specification