Control apparatus for elevator
First Claim
1. In an elevator system including an induction motor operated under variable-voltage and variable-frequency control by an inverter and a pulse generator means producing a detected speed signal representing rotational frequency of the induction motor, a control apparatus comprising:
- (a) compensation means for generating a compensation signal on the basis of an error between a reference speed signal and the detected speed signal,(b) limit means receiving a compensation signal and producing a slip frequency command signal on the basis of the compensation signal, and comparing the slip frequency command signal with a predetermined reference value so as to provide an output slip frequency command signal with a magnitude not exceeding the reference value, and(c) current command generation means for generating a current frequency command signal to be delivered to the inverter on the basis of the output slip frequency command signal of said limit means and a rotational frequency signal of said motor.
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Accused Products
Abstract
In an elevator control system employing a variable-voltage and variable-frequency control, a control apparatus having limiter for limiting the maximum value of a slip frequency ωs when the frequency ω0 of current command values to be delivered to an inverter circuit for operating an induction motor is evaluated in accordance with a condition formula of ω0 =ωs +ω4 (where ωr denotes the angular rotational frequency of the induction motor), whereby an actual car speed can be limited to a safe low value even when the detected car speed is erroneous due to a malfunction of the car speed detection device. Also, the time period during which the generated slip frequency command signal exceeds a reference value is measured to determine the current frequency command signal for the induction motor.
8 Citations
4 Claims
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1. In an elevator system including an induction motor operated under variable-voltage and variable-frequency control by an inverter and a pulse generator means producing a detected speed signal representing rotational frequency of the induction motor, a control apparatus comprising:
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(a) compensation means for generating a compensation signal on the basis of an error between a reference speed signal and the detected speed signal, (b) limit means receiving a compensation signal and producing a slip frequency command signal on the basis of the compensation signal, and comparing the slip frequency command signal with a predetermined reference value so as to provide an output slip frequency command signal with a magnitude not exceeding the reference value, and (c) current command generation means for generating a current frequency command signal to be delivered to the inverter on the basis of the output slip frequency command signal of said limit means and a rotational frequency signal of said motor. - View Dependent Claims (2, 3, 4)
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Specification