Grid-tie inverter for interconnecting AC voltage to electric power grid
First Claim
1. A grid-tie inverter comprising:
- a single-phase or three-phase inverter that performs pulse width modulation for a DC voltage supplied from a DC power supply;
a first capacitor circuit connected to an input side of the inverter so as to form a neutral point;
a second capacitor circuit connected to an output side of the inverter so as to form a neutral point;
a common mode current bypass channel formed by connecting the neutral point of the first capacitor circuit and the neutral point of the second capacitor circuit to each other;
a grounded capacitor provided between the bypass channel and a ground;
a first common mode choke coil unit including a common mode choke coil at least one of between the first capacitor circuit and the inverter and between the inverter and the second capacitor circuit, the first common mode choke coil unit that suppresses a common mode current occurring in the inverter;
an output filter converting a pulse width-modulated voltage waveform outputted from the inverter into a sine single-phase or three-phase AC voltage, the output filter positioned between the inverter and the second capacitor circuit; and
a grid transformer connected to an output side of the second capacitor circuit, a neutral point of the grid transformer connected to the ground through a neutral ground line, whereinat a switching frequency of the inverter, an impedance of the bypass channel is smaller than an impedance of a leakage current channel formed in which a leakage current flows through such a route that goes from the neutral point of the grid transformer to a stray capacitance of the DC power supply through the ground.
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Accused Products
Abstract
According to one embodiment, a grid-tie inverter includes: a inverter performing pulse width modulation for a DC voltage; a first capacitor circuit connected to an input side of the inverter so as to form a neutral point; a second capacitor circuit connected to an output side of the inverter so as to form a neutral point; a common mode current bypass channel formed by connecting the neutral points of the first capacitor circuit and the second capacitor circuit; a grounded capacitor provided between the bypass channel and a ground; a first common mode choke coil unit including a common mode choke coil at least one of between the first capacitor circuit and the inverter and between the inverter and the second capacitor circuit; and an output filter converting a pulse width-modulated voltage outputted from the inverter into a sine AC voltage.
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Citations
16 Claims
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1. A grid-tie inverter comprising:
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a single-phase or three-phase inverter that performs pulse width modulation for a DC voltage supplied from a DC power supply; a first capacitor circuit connected to an input side of the inverter so as to form a neutral point; a second capacitor circuit connected to an output side of the inverter so as to form a neutral point; a common mode current bypass channel formed by connecting the neutral point of the first capacitor circuit and the neutral point of the second capacitor circuit to each other; a grounded capacitor provided between the bypass channel and a ground; a first common mode choke coil unit including a common mode choke coil at least one of between the first capacitor circuit and the inverter and between the inverter and the second capacitor circuit, the first common mode choke coil unit that suppresses a common mode current occurring in the inverter; an output filter converting a pulse width-modulated voltage waveform outputted from the inverter into a sine single-phase or three-phase AC voltage, the output filter positioned between the inverter and the second capacitor circuit; and a grid transformer connected to an output side of the second capacitor circuit, a neutral point of the grid transformer connected to the ground through a neutral ground line, wherein at a switching frequency of the inverter, an impedance of the bypass channel is smaller than an impedance of a leakage current channel formed in which a leakage current flows through such a route that goes from the neutral point of the grid transformer to a stray capacitance of the DC power supply through the ground. - View Dependent Claims (2, 3, 4, 5, 6, 8)
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7. A grid-tie inverter comprising:
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a single-phase or three-phase inverter that performs pulse width modulation for a DC voltage supplied from a DC power supply; a first capacitor circuit connected to an input side of the inverter; a second capacitor circuit connected to an output side of the inverter; a common mode current bypass channel formed by connecting one end of the first capacitor circuit and one end of the second capacitor circuit to each other, or connecting the one end of the first capacitor circuit and a neutral point of the second capacitor circuit, or connecting a neutral point of the first capacitor circuit and the one end of the second capacitor circuit; a capacitor provided in the bypass channel; a grounded capacitor provided between the bypass channel and a ground; a first common mode choke coil unit including a common mode choke coil at least one between the first capacitor circuit and the inverter and between the inverter and the second capacitor circuit, the first common mode choke coil unit that suppresses a common mode current occurring in the inverter; an output filter converting a pulse width-modulated voltage waveform outputted from the inverter into a sine single-phase or three-phase AC voltage, the output filter positioned between the inverter and the second capacitor circuit; and a grid transformer connected to an output side of the second capacitor circuit, a neutral point of the grid transformer connected to the ground through a neutral ground line, wherein at a switching frequency of the inverter, an impedance of the bypass channel is smaller than an impedance of a leakage current channel formed in which a leakage current flows through such a route that goes from the neutral point of the grid transformer to a stray capacitance of the DC power supply through the ground.
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9. A grid-tie inverter comprising;
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a single-phase or three-phase inverter that performs pulse width modulation for a DC voltage supplied from a DC power supply; a first capacitor circuit connected to an input side of the inverter so as to form a neutral point; a second capacitor circuit connected to an output side of the inverter so as to form a neutral point; a common mode current bypass channel formed by connecting the neutral point of the first capacitor circuit and the neutral point of the second capacitor circuit to each other; a first common mode choke coil unit including a common mode choke coil at least one of between the first capacitor circuit and the inverter and between the inverter and the second capacitor circuit, the first common mode choke coil unit that suppresses a common mode current occurring in the inverter; an output filter converting a pulse width-modulated voltage waveform outputted from the inverter into a sine single-phase or three-phase AC voltage, the output filter composed of first reactors and a first capacitor, the output filter positioned between the inverter and the second capacitor circuit; a resonance suppression circuit that suppresses a resonance occurring between inter-winding capacitance of the common mode choke coil and the first reactor of the output filter; and a grid transformer connected to an output side of the second capacitor circuit, a neutral point of the grid transformer connected to the ground through a neutral ground line, wherein at a switching frequency of the inverter, an impedance of the bypass channel is smaller than an impedance of a leakage current channel formed in which a leakage current flows through such a route that goes from the neutral point of the grid transformer to a stray capacitance of the DC power supply through the ground. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification