Power converter
First Claim
1. A power converter, comprising:
- a converter;
a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential;
a three-level NPC inverter connected to said three-level DC voltage source;
a chopper circuit; and
chopper control means for controlling said chopper circuit;
said chopper circuit including,a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source,a first diode connected in antiparallel with said first switching device,a second diode connected in antiparallel with said second switching device, anda reactor,an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source,a cathode of said first switching device being connected to an anode of said second switching device,a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source,said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices;
said chopper control means including,first voltage detecting means for detecting a first voltage between one of said capacitors,second voltage detecting means for detecting a second voltage between the other of said capacitors,voltage control means connected to receive said first voltage and said second voltage for comparing said first voltage with said second voltage to generate a voltage difference and for generating a voltage control output signal so that said voltage difference becomes zero, andcontrol means connected to receive said voltage control output signal for driving said first and second switching devices based on said voltage control output signal;
whereby to suppress the fluctuation of said neutral potential of said three-level DC power source.
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Accused Products
Abstract
A power converter including, a converter, a three-level DC voltage source composed of a series connected capacitors connected between outputs of the converter to generate a positive, a neutral and a negative potential, a three-level NPC inverter, a chopper circuit, and a chopper control circuit. The chopper circuit includes a series circuit of a first and a second switching device connected between a positive and a negative potential points of the three-level DC voltage source, a first and a second diode connected in antiparallel with the first and second switching devices, respectively, and a reactor connected between a neutral potential point and a connecting point of the first and second switching devices. The chopper control circuit includes a first and a second voltage detector for detecting a first and a second voltages between the capacitors, respectively, a voltage controller for comparing the first and second voltages and for generating a voltage control output signal so that a voltage difference becomes zero, and a control circuit for driving the first and second switching devices based on the voltage control output signal. Whereby the fluctuation of the neutral potential of the three-level DC power source is suppressed.
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Citations
17 Claims
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1. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first voltage detecting means for detecting a first voltage between one of said capacitors, second voltage detecting means for detecting a second voltage between the other of said capacitors, voltage control means connected to receive said first voltage and said second voltage for comparing said first voltage with said second voltage to generate a voltage difference and for generating a voltage control output signal so that said voltage difference becomes zero, and control means connected to receive said voltage control output signal for driving said first and second switching devices based on said voltage control output signal; whereby to suppress the fluctuation of said neutral potential of said three-level DC power source. - View Dependent Claims (3)
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2. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a first reactor connected in the forward direction between a positive potential point and a neutral point of said three-level DC power source, a first diode connected in the reverse direction between a connecting point of said first switching device and said first reactor and a negative potential point of said three-level DC power source, a series circuit of a second switching device and a second reactor connected in the forward direction between said negative potential point and said neutral point of said three-level DC power source, a second diode connected in the reverse direction between a connecting point of said second switching device and said second reactor and said positive potential point of said three-level DC power source, said chopper control means including, first voltage detecting means for detecting a first voltage between one of said capacitors, second voltage detecting means for detecting a second voltage between the other of said capacitors, voltage control means connected to receive said first voltage and said second voltage for comparing said first voltage with said second voltage to generate a voltage difference and for generating a voltage control output signal so that said voltage difference becomes zero, and control means connected to receive said voltage control output signal for driving said first and second switching devices based on said voltage control output signal; whereby to suppress the fluctuation of said neutral potential of said three-level DC power source.
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4. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first arm and a second arm connected between a positive side potential point and a negative side potential point of said three-level DC voltage source, each of said first and second arms composed of a series circuit of a first switching device and a second switching device, a first diode connected in antiparallel with said first switching device, and a second diode connected in antiparallel with said second switching device, a third diode connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices in said first arm, a fourth diode connected between said neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices in said second arm, and a reactor connected between said neutral potential point of said three-level DC voltage source and a connecting point of said first and second arms, an anode of said first switching device of said first arm being connected to said positive side potential point of said three-level DC voltage source, a cathode of said second switching device of said first arm being connected to an anode of said first switching device of said second arm, a cathode of said second switching device of said second arm being connected to said negative side potential point of said three-level DC voltage source; said chopper control means including, first voltage detecting means for detecting a first voltage between one of said capacitors, second voltage detecting means for detecting a second voltage between the other of said capacitors, voltage control means connected to receive said first voltage and said second voltage for comparing said first voltage with said second voltage to generate a voltage difference and for generating a voltage control output signal so that said voltage difference becomes zero, and control means connected to receive said voltage control output signal for driving said first and second switching devices in said first and second arms based on said voltage control output signal, such that one arm of said first and second arms is turned ON based on said voltage control output signal and a current is flown through said reactor from one of said capacitors, then said switching device of said three-level DC voltage source side is turned OFF and said current flowing through said reactor is circulated and stored through one of said third and fourth diodes, and then said switching device of the other side is turned OFF and said current stored in said reactor is discharged through the other of said capacitors and the other arm; whereby to suppress the fluctuation of said neutral potential of said three-level DC power source. - View Dependent Claims (5)
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6. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first current detecting means for detecting a chopper current flowing through said reactor, second current detecting means for detecting an inverter neutral current flowing between said neutral potential point of said three-level DC voltage source and a neutral potential point of said three-level NPC inverter, comparator means for comparing said inverter neutral current with said chopper current to generate a current difference therebetween, current control means connected to receive said current difference for generating a current control output signal so that said current difference becomes zero, and control means connected to receive said current control output signal for driving said first and second switching devices based on said current control output signal.
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7. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first current detecting means for detecting a chopper current flowing through said reactor, inverter neutral current computing means for computing an inverter neutral current flowing between said neutral potential point of said three-level DC voltage source and a neutral potential point of said three-level NPC inverter, comparator means for comparing said computed inverter neutral current with said chopper current to generate a current difference therebetween, current control means connected to receive said current difference for generating a current control output signal so that said current difference becomes zero, and control means connected to receive said current control output signal for driving said first and second switching devices based on said current control output signal. - View Dependent Claims (8, 9)
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10. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first current detecting means for detecting a chopper current flowing through said reactor, second current detecting means for detecting an inverter neutral current flowing between said neutral potential point of said three-level DC voltage source and a neutral potential point of said three-level NPC inverter, inverter neutral current computing means for computing an inverter neutral current flowing between said neutral potential point of said three-level DC voltage source and a neutral potential point of said three-level NPC inverter, first comparator means for comparing said computed inverter neutral current with said chopper current to generate a first current difference therebetween, second comparator means for comparing said detected inverter neutral current with said chopper current to generate a second current difference therebetween, current control means connected to receive said first and second current differences for generating a current control output signal so that said first and second current differences become zero, and control means connected to receive said current control output signal for driving said first and second switching devices based on said current control output signal, said current control means including a proportional compensator connected to receive said first current difference for proportional control, an integral compensator connected to receive said second current difference for integral control and an adder for adding an output of said proportional compensator and an output of said integral compensator to generate said current control output signal so that said first and second current differences become zero. - View Dependent Claims (11, 16, 17)
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12. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first voltage detecting means for detecting a first voltage between one of said capacitors, second voltage detecting means for detecting a second voltage between the other of said capacitors, voltage comparator means for comparing said first voltage with said second voltage to generate a voltage difference, voltage control means connected to receive said voltage difference for generating a voltage control output signal so that said voltage difference becomes zero, and control means connected to receive said voltage control output signal for driving said first and second switching devices based on said voltage control output signal. - View Dependent Claims (13, 14)
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15. A power converter, comprising:
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a converter; a three-level DC voltage source, composed of a series connected capacitors connected between outputs of said converter, to generate a positive potential, a neutral potential and a negative potential; a three-level NPC inverter connected to said three-level DC voltage source; a chopper circuit; and chopper control means for controlling said chopper circuit; said chopper circuit including, a series circuit of a first switching device and a second switching device connected between a positive potential point and a negative potential point of said three-level DC voltage source, a first diode connected in antiparallel with said first switching device, a second diode connected in antiparallel with said second switching device, and a reactor, an anode of said first switching device being connected to said positive side potential point of said three-level DC voltage source, a cathode of said first switching device being connected to an anode of said second switching device, a cathode of said second switching device being connected to said negative side potential point of said three-level DC voltage source, said reactor being connected between a neutral potential point of said three-level DC voltage source and a connecting point of said first and second switching devices; said chopper control means including, first current detecting means for detecting a chopper current flowing through said reactor, second current detecting means for detecting an inverter neutral current flowing between said neutral potential point of said three-level DC voltage source and a neutral potential point of said three-level NPC inverter, comparator means for comparing said inverter neutral current with said chopper current to generate a current difference, integrating means connected to receive said current difference for integrating said current difference, voltage control means connected to receive an output signal of said integrating means for generating a voltage control output signal so that said output signal of said integrating means becomes zero, a stabilizing compensator connected to receive said chopper current detected by said first current detecting means for proportional control, and subtractor means for subtracting an output signal of said stabilizing compensator from said voltage control output signal of said voltage control means, and control means connected to receive an output signal of said subtractor means for driving said first and second switching devices based on said output signal of said subtractor means.
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Specification