Three level power converting apparatus having means for balancing DC component thereof
First Claim
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1. A power converting apparatus comprising:
- a plurality of capacitors connected in series across a DC voltage source, converter for converting DC voltages supplied from the capacitors to an AC phase voltage having three potentials, including a positive, zero, and negative potential, andzero-voltage adjuster for adjusting a zero-voltage duration of the AC phase voltage on a basis of an output current polarity of the power converting apparatus and a value representing a voltage difference between the voltages of the capacitors connected in series so as to balance the voltages.
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Abstract
In order to equalize voltage shares of DC-side voltage dividing capacitors of a three-level power converting apparatus for converting a DC voltage to a three-level AC phase voltage, there is provided an arrangement for compensating for rising and falling instances of a three-level AC voltage pulse depending on a difference voltage between the two voltage dividing capacitors and the polarity of the AC current, thereby adjusting a zero-voltage period of the AC voltage.
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Citations
10 Claims
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1. A power converting apparatus comprising:
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a plurality of capacitors connected in series across a DC voltage source, converter for converting DC voltages supplied from the capacitors to an AC phase voltage having three potentials, including a positive, zero, and negative potential, and zero-voltage adjuster for adjusting a zero-voltage duration of the AC phase voltage on a basis of an output current polarity of the power converting apparatus and a value representing a voltage difference between the voltages of the capacitors connected in series so as to balance the voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A power converting apparatus comprising:
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a plurality of capacitors connected in series across a DC voltage source, converter for converting DC voltages supplied from the capacitors to an AC phase voltage having three potentials, including a positive, zero, and negative potential, at least one current polarity detector disposed between said converter for converting and a load, for detecting an output current polarity of a current flowing between said means for converting and said load, and zero-voltage adjuster for adjusting a zero-voltage duration of the AC phase voltage on a basis of said output current polarity of the power converting apparatus and a value representing a voltage difference between the voltages of the capacitors connected in series so as to balance the voltages.
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9. A power converting apparatus comprising:
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a plurality of capacitors connected in series across a DC voltage source, converter for converting DC voltages supplied from the capacitors to at least two AC phase voltages having three potentials, including a positive, zero, and negative potential, and outputting each AC phase voltage of said at least two AC phase voltages on a separate output line, a current polarity detector disposed on each output line between said converter for converting and a load, for detecting output current polarities of phase currents flowing between said converter for converting and said load, and zero-voltage converter for adjusting a zero-voltage duration of the AC phase voltage on a basis of said output current polarities of the power converting apparatus and a value representing a voltage difference between the voltages of the capacitors connected in series so as to balance the voltages.
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10. A power converting apparatus comprising:
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a plurality of capacitors connected in series across a DC voltage source, converter for converting DC voltages supplied from the capacitors to three AC phase voltages having three potentials, including a positive, zero, and negative potential, and outputting each AC phase voltage of said three AC phase voltages on a separate output line, a current polarity detector disposed on each output line between said converter for converting and a load, for detecting output current polarities of three phase currents flowing between said converter for converting and said load, and zero-voltage adjuster for adjusting a zero-voltage duration of the AC phase voltage on a basis of said output current polarities of the power converting apparatus and a value representing a voltage difference between the voltages of the capacitors connected in series so as to balance the voltages.
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Specification