Control method and device for AC motor
First Claim
1. A control method for an AC motor designed, in transforming output power of a converter to AC power by an inverter for driving said AC motor with the AC power, to detect an AC current in the inverter output side and a Dc voltage in the inverter input side, calculate an inverter input average current for an integer multiple of a carrier half-cycle from said detected current, calculate input power of said inverter from said calculated average current and said detected DC voltage, produce a source current value by dividing said calculated input power by the AC voltage in the converter input side, produce a source current command value from said detected DC voltage in the inverter input side and an output voltage command indicating the target output voltage of said converter for restraining the deviation therebetween to become zero, modify said source current command value in accordance with said source current value, and apply a pulse signal based on said modified source current command value to said converter for controlling said converter so that an AC current in the converter input side follows said modified source current command value.
1 Assignment
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Accused Products
Abstract
In a control method and device for an AC motor, when transforming output power of a converter to AC power by an inverter and controlling the AC motor with the AC power, a source current value is determined from the value of an electric variable in the input or output side of the inverter, and the converter is controlled in accordance with the source current value. This makes the source current free from an influence of ripple components. Accordingly, even when the load of the AC motor is fluctuated abruptly, the required AC power can be applied to the converter so as to follow such fluctuations.
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Citations
41 Claims
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1. A control method for an AC motor designed, in transforming output power of a converter to AC power by an inverter for driving said AC motor with the AC power, to detect an AC current in the inverter output side and a Dc voltage in the inverter input side, calculate an inverter input average current for an integer multiple of a carrier half-cycle from said detected current, calculate input power of said inverter from said calculated average current and said detected DC voltage, produce a source current value by dividing said calculated input power by the AC voltage in the converter input side, produce a source current command value from said detected DC voltage in the inverter input side and an output voltage command indicating the target output voltage of said converter for restraining the deviation therebetween to become zero, modify said source current command value in accordance with said source current value, and apply a pulse signal based on said modified source current command value to said converter for controlling said converter so that an AC current in the converter input side follows said modified source current command value.
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2. A control method for an AC motor designed, in transforming output power of a converter to AC power by an inverter for driving said AC motor with the AC power, to detect an AC current in the inverter output side and a DC voltage in the inverter input side, calculate an inverter input average current for an integer multiple of a carrier half-cycle from said detected current and a penetration factor of a pulse signal applied to a switching element of said inverter, calculate input power of said inverter from said calculated average current and said detected DC voltage, produce a source current value by dividing said calculated input power by the AC voltage in the converter input side, produce a source current command value, from said detected DC voltage in the inverter input side and an output voltage command indicating the target output voltage of said converter for restraining the deviation therebetween to become zero, modify said source current command value in accordance with said source current value, and apply a pulse signal based on said modified source current command value to said converter for controlling said converter so that an AC current in the converter input side follows said modified source current command value.
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3. A control device for an AC motor comprising a converter for transforming AC power to DC power;
- an inverter for transforming output power of said converter to AC power for driving said AC motor;
inverter control means for producing a pulse signal in accordance with a frequency command for said AC motor, and applying said pulse signal to said inverter to control an output voltage of said inverter;
current detecting means for detecting an AC current in the inverter output side;
power calculating means for calculating inverter input average power for an integer multiple of a carrier half-cycle of said inverter based of the detected output of said current detecting means;
source current valve calculating means for calculating a source current value by dividing the calculated power of said power calculating means by the AC voltage in the converter input side;
voltage detecting means for detecting a DC voltage in the inverter input side;
source current command value producing means for producing a source current command value adapted to restrain the deviation between the detected output of said voltage detecting means and a DC voltage command indicating the target output voltage of said converter to become zero;
amplitude command producing means for producing an amplitude command to specify an amplitude of a source current from said source current command value and said source current value;
source phase detecting means for detecting phase of a source current in the converter input side;
AC current command producing means for producing an AC current command from the detected output of said source phase detecting means and said amplitude command;
input current detecting means for detecting an input current of said converter; and
converter control means for controlling said converter by applying, to said converter, a pulse signal adapted to restrain the deviation between the detected output of said input current detecting means and said AC current command.
- an inverter for transforming output power of said converter to AC power for driving said AC motor;
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4. A control device for an AC motor comprising a converter for transforming AC power to DC power;
- an inverter for transforming output power of said converter to AC power for driving said AC motor;
inverter control means for producing a pulse signal in accordance with a frequency command for said AC motor, and applying said pulse signal to said inverter to control an output voltage of said inverter;
current detecting means for detecting an AC current in the inverter output side;
voltage detecting means for detecting a DC voltage in the inverter input side;
average current calculating means for calculating an inverter input average current for an integer multiple of a carrier half-cycle of said inverter based on the detected output of said current detecting means;
power calculating means for calculating inverter input average power from the calculated average current of said average current calculating means and the detected output of said voltage detecting means;
source current value calculating means for producing a source current value by dividing the calculated power of said power calculating means by the AC voltage in the converter input side;
source current command value producing means for producing a source current command value adapted to restrain the deviation between the detected output of said voltage detecting means and an output voltage command indicating the target output voltage of said converter to become zero;
amplitude command producing means for producing an amplitude command for a source current by modifying said source current command value in accordance with said source current value;
source phase detecting means for detecting phase of a an AC power source in the converter input side;
AC current command producing means for producing an AC current command from the detected output of said source phase detecting means and said amplitude command;
input current detecting means for detecting an input current of said converter; and
converter control means for controlling said converter by applying, to said converter, a pulse signal adapted to restrain the deviation between the detected output of said input current detecting means and said AC current command.
- an inverter for transforming output power of said converter to AC power for driving said AC motor;
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5. A method of controlling an AC motor system including an AC motor, an inverter, and a converter, the AC motor being driven by AC power transformed by the inverter from DC output power of the converter, the converter receiving AC power from an AC power source, the method comprising the steps of:
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detecting an operational parameter of the AC motor system; calculating a power of the inverter based on the detected operational parameter; producing a voltage command specifying a desired output voltage of the converter; detecting an output voltage of the converter; producing an operational parameter command based on a difference between the detected output voltage and the voltage command; producing a source current amplitude command based on the produced operational parameter command and the calculated power of the inverter; and controlling the converter based on the source current amplitude command such the difference between the detected output voltage and the voltage command is reduced to zero and such that an input current of the converter follows the source current amplitude command. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A device for controlling an AC motor system including an AC motor, an inverter, and a converter, the AC motor being driven by AC power transformed by the inverter from DC output power of the converter, the converter receiving AC power from an AC power source, the device comprising:
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means for detecting an operational parameter of the AC motor system; means for calculating a power of the inverter based on the detected operational parameter; means for producing a voltage command specifying a desired output voltage of the converter; means for detecting an output voltage of the converter; means for producing an operational parameter command based on a difference between the detected output voltage and the voltage command; means for producing a source current amplitude command based on the produced operational parameter command and the calculated power of the inverter; and means for controlling the converter based on the source current amplitude command such the difference between the detected output voltage and the voltage command is reduced to zero and such that an input current of the converter follows the source current amplitude command. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification