Power converter
First Claim
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1. A power converter comprising:
- an inverter that converts a DC voltage or an AC voltage to an AC voltage of an arbitrary frequency to drive an AC motor having a permanent magnet therein;
an opening/closing unit that is connected between the inverter and the AC motor;
a controller that controls the inverter and the opening/closing unit;
a voltage detector provided between the opening/closing unit and the AC motor; and
a current detector provided between the inverter and the opening/closing unit, wherein when the inverter is turned OFF, the controller compares an induced voltage in a state where the inverter is turned OFF with an induced voltage in a normal state to detect abnormality of the AC motor,wherein when the AC motor is in an abnormal state, the controller turns OFF the opening/closing unit, andwherein when a current larger than a predetermined threshold value is still detected by the current detector even though the opening/closing unit is turned OFF, the controller determines that the opening/closing unit is in an abnormal state or the current is excessive as compared with an interruption capacity of the opening/closing unit, and performs a predetermined procedure to reduce a number of revolutions of the AC motor.
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Abstract
In a power converter a controller determines that an AC motor is in an abnormal state when a voltage of each phase of the AC motor detected by a voltage detector is in an unbalanced state where the voltage exceeds a predetermined value, and turns an opening/closing unit OFF to prevent damage generated in the AC motor from becoming worse. Moreover, the controller determines abnormality of the opening/closing unit based on a current of each phase detected by a current detector, and the controller performs control to reduce the number of revolutions of the AC motor upon determining that at least one of the AC motor and the opening/closing unit is in an abnormal state.
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Citations
12 Claims
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1. A power converter comprising:
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an inverter that converts a DC voltage or an AC voltage to an AC voltage of an arbitrary frequency to drive an AC motor having a permanent magnet therein; an opening/closing unit that is connected between the inverter and the AC motor; a controller that controls the inverter and the opening/closing unit; a voltage detector provided between the opening/closing unit and the AC motor; and a current detector provided between the inverter and the opening/closing unit, wherein when the inverter is turned OFF, the controller compares an induced voltage in a state where the inverter is turned OFF with an induced voltage in a normal state to detect abnormality of the AC motor, wherein when the AC motor is in an abnormal state, the controller turns OFF the opening/closing unit, and wherein when a current larger than a predetermined threshold value is still detected by the current detector even though the opening/closing unit is turned OFF, the controller determines that the opening/closing unit is in an abnormal state or the current is excessive as compared with an interruption capacity of the opening/closing unit, and performs a predetermined procedure to reduce a number of revolutions of the AC motor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A power converter comprising:
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an inverter that converts a DC voltage or an AC voltage to an AC voltage of an arbitrary frequency to drive an AC motor having a permanent magnet therein; an opening/closing unit that is connected between the inverter and the AC motor; a voltage detector provided between the opening/closing unit and the AC motor; a controller that controls the inverter and the opening/closing unit, and a current detector provided between the inverter and the opening/closing unit, wherein when the inverter is turned OFF, the controller compares an induced voltage in a state where the inverter is turned OFF with an induced voltage in a normal state to detect abnormality of the AC motor, wherein when the AC motor is in an abnormal state, the controller turns OFF the opening/closing unit, and wherein when an abnormal induced voltage is still detected by the voltage detector even though the opening/closing unit is turned OFF, the controller determines that there is a possibility that an interphase short circuit or ground fault occurs in a part of a stator coil of the AC motor, and performs a predetermined procedure to reduce a number of revolutions of the AC motor. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification