Current/voltage control apparatus for elevator system
First Claim
1. A current/voltage control apparatus for an elevator system including an inverter for inverting a direct-current voltage into an alternating-current voltage of a variable voltage-and-frequency-type to be applied to an induction motor, an inverter controller for detecting a current phase flowing in the induction motor, generating a voltage instruction based on the detected phase and controlling the inverter, and an inverter driving unit for receiving an output signal from the inverter controller, generating a pulse width modulation signal corresponding thereto and driving the inverter, said control apparatus comprising:
- a voltage limiter for setting a limit voltage value which is proportional to an operational frequency of the induction motor and applying the voltage below the limit voltage value to the inverter driving unit;
a zero phase component current detector for detecting a zero phase component current and outputting an inverter driving stop signal to the inverter driving unit when the thusly detected current exceeds a predetermined reference value; and
a current deviation detector for detecting a current deviation value and outputting an inverter driving stop signal to the inverter driving unit when the current deviation value exceeds a predetermined reference value continuously for a predetermined time.
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Accused Products
Abstract
A current/voltage control apparatus for an elevator system which is capable of preventing an over current from being applied to an inverter by stopping a driving operation of the inverter when a difference (hereinafter called "current deviation") between a current instruction and actual current value exceed a predetermined value during a predetermined time. The apparatus includes a voltage limiter for setting a limit voltage value which is proportional to an operational frequency of the induction motor and applying the voltage below the limit voltage value to the inverter driving unit, a zero phase component current detector for detecting a zero phase component current and outputting an inverter driving stop signal to the inverter driving unit when the thusly detected current exceeds a predetermined reference value, and a current deviation detector for detecting a current deviation value and outputting an inverter driving stop signal to the inverter driving unit when the current deviation value, which exceeds a predetermined reference value, is continuously maintained for a predetermined time.
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Citations
15 Claims
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1. A current/voltage control apparatus for an elevator system including an inverter for inverting a direct-current voltage into an alternating-current voltage of a variable voltage-and-frequency-type to be applied to an induction motor, an inverter controller for detecting a current phase flowing in the induction motor, generating a voltage instruction based on the detected phase and controlling the inverter, and an inverter driving unit for receiving an output signal from the inverter controller, generating a pulse width modulation signal corresponding thereto and driving the inverter, said control apparatus comprising:
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a voltage limiter for setting a limit voltage value which is proportional to an operational frequency of the induction motor and applying the voltage below the limit voltage value to the inverter driving unit; a zero phase component current detector for detecting a zero phase component current and outputting an inverter driving stop signal to the inverter driving unit when the thusly detected current exceeds a predetermined reference value; and a current deviation detector for detecting a current deviation value and outputting an inverter driving stop signal to the inverter driving unit when the current deviation value exceeds a predetermined reference value continuously for a predetermined time. - View Dependent Claims (2, 3, 4)
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5. A current voltage control apparatus for an elevator system including an inverter for inverting a direct-current voltage into a variable voltage-and-frequency-type of alternating-current voltage to be applied to an induction motor, and an inverter controller for detecting a current phase flowing in the induction motor, for generating a voltage instruction based on the detected phase and for controlling the inverter, said control apparatus comprising:
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a voltage limiter to limit maximum values of control signals from said inverter controller as a function of an operation frequency of said induction motor, said voltage limiter producing upper-bounded control signals; and an inverter driving unit for generating a pulse width modulation signal to drive said inverter based upon said upper-bounded control signals. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A current voltage control apparatus for an elevator system including an inverter for inverting a direct-current voltage into a variable voltage-and-frequency-type of alternating-current voltage to be applied to an induction motor, said control apparatus comprising:
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a voltage limiter to produce upper-bounded control signals; an inverter driving unit for generating a pulse width modulation signal to drive said inverter based upon said upper-bounded control signals; a zero-phase-component current detector to detect a zero phase component current flowing in the induction motor and to provide a first inverter driving stop signal to said inverter driving unit when said zero-phase-component current detector determines that said current exceeds a predetermined reference value; and a current deviation detector to provide a second inverter driving stop signal to said inverter driving unit based upon at least one of a Q-axis current derived from motor currents flowing in said induction motor and a D-axis current derived from said motor currents. - View Dependent Claims (12, 13, 14, 15)
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Specification