Procedure for starting an elevator
First Claim
1. A method for starting elevator machinery which includes a synchronous motor fed by a frequency converter and a traction sheave connected to the motor to move the elevator car with hoisting ropes, said method comprising the steps of:
- measuring an elevator load; and
generating a torque corresponding to the load applied to the shaft of the elevator motor at the time of starting, wherein said generating step is achieved by,when the motor stops, feeding the motor with a d.c. current and, from the frequency converter, determining the angle of the magnetic field of the stator of the synchronous motor,determining the change of the load signal during stoppage,when the motor is started again, determining a new value of the angle of the magnetic field of the stator based on the change in the load signal and the angle of the magnetic field of the rotor which has been held constant during elevator stoppage, andadjusting the frequency converter so that a magnetic field with a direction corresponding to the new angle of the magnetic field of the stator is generated in the motor.
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Accused Products
Abstract
In a system for starting elevator machinery driven by a synchronous motor, current is fed to the motor by a frequency converter and a traction sheave is connected to the motor to move the elevator car with hoisting ropes. The angle of the magnetic field of the stator is determined when the elevator stops. When the motor is started again, a new value of the angle of the magnetic field of the stator is determined on the basis of the change in the load signal. The frequency converter is adjusted so that a magnetic field whose direction corresponds to the new angle of the magnetic field of the stator is generated in the motor.
13 Citations
17 Claims
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1. A method for starting elevator machinery which includes a synchronous motor fed by a frequency converter and a traction sheave connected to the motor to move the elevator car with hoisting ropes, said method comprising the steps of:
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measuring an elevator load; and generating a torque corresponding to the load applied to the shaft of the elevator motor at the time of starting, wherein said generating step is achieved by, when the motor stops, feeding the motor with a d.c. current and, from the frequency converter, determining the angle of the magnetic field of the stator of the synchronous motor, determining the change of the load signal during stoppage, when the motor is started again, determining a new value of the angle of the magnetic field of the stator based on the change in the load signal and the angle of the magnetic field of the rotor which has been held constant during elevator stoppage, and adjusting the frequency converter so that a magnetic field with a direction corresponding to the new angle of the magnetic field of the stator is generated in the motor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for controlling elevator moving machinery which includes a synchronous motor having a rotor and stator, a frequency converter for feeding current to the synchronous motor, and a controller for adjusting the characteristics of the current fed from the frequency converter to the synchronous motor, said method comprising the steps of:
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determining, at the time the elevator car is initially stopped (time t1), the direction of the magnetic field created by the rotor; sensing a starting load value at the time the elevator car is to be moved from the stopped position (time t2); determining, at time t2, the direction of the magnetic field generated by the stator in accordance with the rotor magnetic field direction and the starting load value determined at time t2; and generating a stator magnetic field when the synchronous motor is restarted to produce a torque corresponding to the starting load value. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An apparatus for moving a stopped elevator car comprising:
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a synchronous motor having a rotor and a stator, the rotor being stopped at time t1 and held constant when the elevator is stopped; a frequency converter for feeding current to the stator of said synchronous motor; a load sensor for sensing a load value at the time the elevator car is to be moved from the stopped position (time t2); and a controller for adjusting the characteristics of the current fed from the frequency converter to the synchronous motor, said controller determining the direction of the stator magnetic field at time t2 in accordance with the sensed load value and the direction of the rotor magnetic field at time t1, said controller controlling said frequency converter to create, at time t2, a stator magnetic field at the determined direction to thereby create a torque corresponding to the load at time t2. - View Dependent Claims (14, 15, 16, 17)
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Specification