Inverter apparatus and method of reducing speed of alternating current motor
First Claim
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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, anda 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, whereinin 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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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.
18 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, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 26)
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16. 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 (17, 18, 19, 20, 21, 22, 23, 24, 25, 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