AC elevator control system
First Claim
1. An AC elevator control system comprising an elevator car and a counter weight connected to both ends of a traction rope respectively, a sheave over which said traction rope is trained, an induction motor for driving said sheave, a converter for converting an AC power to a direct current, an inverter for inverting said direct current from said converter to an AC power with a variable voltage at a variable frequency to supply said AC power to said induction motor, a battery connected across the DC side of said inverter and forming an electric source for actuating said inverter upon the occurrence of a power failure and/or a fault and a command emergency frequency generator responsive to the occurrence of a power failure or fault for delivering a low frequency command emergency signal to said inverter so as to not generate regenerative power with said inductive motor;
- wherein said command emergency frequency signal from said command emergency frequency generator, is set to a value as determined by the relationship between a difference in weight between said elevator car and said counter weight and various losses of a system for driving said induction motor.
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Accused Products
Abstract
An AC elevator control system has a converter for converting a three-phase AC power to a direct current, an inverter for inverting the direct current to a three-phase AC power with a variable voltage at a variable frequency, and a three-phase induction motor for receiving the last-mentioned AC power to operate an elevator car connected to a counterweight through a traction rope trained over a sheave. A battery connected across the DC side of the inverter is enabled upon the occurrence of a power failure or a fault. A command emergency frequency generator responds to the occurrence of an emergency such as a power failure to deliver to the inverter a low frequency emergency frequency as determined by the relationship between a difference in weight between the elevator car and the counterweight and various losses of a motor driving system so as to cause the induction motor not to generate regenerative power.
33 Citations
4 Claims
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1. An AC elevator control system comprising an elevator car and a counter weight connected to both ends of a traction rope respectively, a sheave over which said traction rope is trained, an induction motor for driving said sheave, a converter for converting an AC power to a direct current, an inverter for inverting said direct current from said converter to an AC power with a variable voltage at a variable frequency to supply said AC power to said induction motor, a battery connected across the DC side of said inverter and forming an electric source for actuating said inverter upon the occurrence of a power failure and/or a fault and a command emergency frequency generator responsive to the occurrence of a power failure or fault for delivering a low frequency command emergency signal to said inverter so as to not generate regenerative power with said inductive motor;
wherein said command emergency frequency signal from said command emergency frequency generator, is set to a value as determined by the relationship between a difference in weight between said elevator car and said counter weight and various losses of a system for driving said induction motor. - View Dependent Claims (2)
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3. An AC elevator control system comprising an elevator car and a counter weight connected to both ends of a traction rope respectively, a sheave over which said traction rope is trained, an induction motor for driving said sheave, a converter for converting an AC power to a direct current, an inverter for inverting said direct current from said converter to an AC power with a variable voltage at a variable frequency to supply said AC power to said induction motor, a battery connected across the DC side of said inverter and forming an electric source for actuating said inverter upon the occurrences of a power failure and/or a fault and a command emergency frequency generator responsive to the occurrence of a power failure or fault for delivering a low frequency command emergency signal to said inverter so as to not generate regenerative power with said inductive motor;
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wherein said command emergency frequency generator includes a pulse oscillator for generating a train of pulses having a constant pulse repetition frequency, a counter supplied with said train of pulses from said pulse oscillator and a count direction changing signal used to pulse-modulate said pulses supplied thereto, a decoder connected to said counter, and a plurality of "OR" gates a connected to said decoder producing said command emergency frequency signal; and wherein said command emergency frequency signal from said command emergency frequency generator, is set to a value as determined by the relationship between a difference in weight between said elevator car and said counter weight and various losses of a system for driving said induction motor. - View Dependent Claims (4)
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Specification