Inverter Apparatus and Method of Reducing Speed of Alternating Current Motor
First Claim
1. An inverter apparatus comprising:
- a converter portion for converting an alternating current voltage into a direct current voltage, a capacitor for smoothing the direct current voltage, an inverter portion for driving an alternating current motor by converting the direct current voltage into an alternating current, a current converting portion for generating a detecting value of a current flowing in the motor, and a PWM calculating portion for generating a signal for driving a gate of a power element, a direct current voltage detecting portion for detecting the direct current voltage;
a first filter portion and a second filter portion constituting two low pass filters for filtering an output of the direct current voltage detecting portion;
a speed reducing rate setting portion for setting a speed reducing time period of the motor;
a speed reducing rate calculating portion for calculating a frequency of driving the motor from an output of the first filter portion and an output of the speed reducing rate setting portion; and
a voltage command correcting portion for correcting a voltage command from an output of the second filter portion and a given voltage command, wherein in speed reducing, a time constant of the second filter portion is constituted by 10 through 10000 times as much as a time constant of the first filter portion.
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Accused Products
Abstract
There is provided an inverter capable of reducing a speed in a short period of time without generating an overcurrent even in a case of an alternating current motor which is easy to be saturated magnetically. A frequency of driving a motor is calculated by using a detecting value constituted by passing a direct current bus line voltage through a first filter portion, a voltage command is corrected by using a detecting value passing through a second filter portion, by making a time constant of the second filter portion larger than a time constant of the first filter portion in reducing a speed, the motor is brought into an overexcited state and loss is brought about in the motor.
23 Citations
30 Claims
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1. An inverter apparatus comprising:
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a converter portion for converting an alternating current voltage into a direct current voltage, a capacitor for smoothing the direct current voltage, an inverter portion for driving an alternating current motor by converting the direct current voltage into an alternating current, a current converting portion for generating a detecting value of a current flowing in the motor, and a PWM calculating portion for generating a signal for driving a gate of a power element, a direct current voltage detecting portion for detecting the direct current voltage;
a first filter portion and a second filter portion constituting two low pass filters for filtering an output of the direct current voltage detecting portion;
a speed reducing rate setting portion for setting a speed reducing time period of the motor;
a speed reducing rate calculating portion for calculating a frequency of driving the motor from an output of the first filter portion and an output of the speed reducing rate setting portion; and
a voltage command correcting portion for correcting a voltage command from an output of the second filter portion and a given voltage command, wherein in speed reducing, a time constant of the second filter portion is constituted by 10 through 10000 times as much as a time constant of the first filter portion. - View Dependent Claims (2, 3, 4, 5, 11, 12, 13, 14, 15, 21, 22, 23, 24, 25)
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6. A method of reducing a speed of a motor of an inverter apparatus including:
- a converter portion for converting an alternating current voltage into a direct current voltage, a capacitor for smoothing the direct current voltage, an inverter portion for driving an alternating current motor by converting the direct current voltage into an alternating current, a current converting portion for generating a current detecting value, and a PWM calculating portion for generating a signal for driving a gate of a power element of the inverter portion;
the method comprising;
a step of detecting the direct current voltage;
a step of calculating the current detecting value;
a step of filtering the direct current voltage by a first filter portion;
a step of filtering the direct current voltage by a second filter portion by a time constant the same as a time constant of the first filter portion in normal operation and by a time constant larger than the time constant of the first filter portion by a multiplication factor of 10 through 10000 in speed reducing;
a step of calculating a frequency of driving the motor by a speed reducing rate set by a speed reducing rate setting portion for setting a speed reducing time period of the motor and an output of the first filter portion; and
a step of correcting a voltage command from an output of the second filter portion and a given voltage command. - View Dependent Claims (7, 8, 9, 10, 16, 17, 18, 19, 20, 26, 27, 28, 29, 30)
- a converter portion for converting an alternating current voltage into a direct current voltage, a capacitor for smoothing the direct current voltage, an inverter portion for driving an alternating current motor by converting the direct current voltage into an alternating current, a current converting portion for generating a current detecting value, and a PWM calculating portion for generating a signal for driving a gate of a power element of the inverter portion;
Specification