Elevator machine braking
AssigneeOtis Elevator Company
InventorPrasanna Nagarajan
Life of this patent
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Abstract
An elevator machine assembly includes a motor and an elevator drive configured to control power supply to the motor. The elevator drive includes at least a plurality of converter switches and an energy storage device that is situated to be charged in response to the motor generating a back emf as the motor rotates in response to a torque applied to the motor when the elevator drive is not providing power to the motor. A short-circuiting module that is selectively coupled with the energy storage device through the converter switches selectively discharges the energy storage device to limit the back emf of the motor and a corresponding speed at which the motor rotates.
Claims20
An elevator machine assembly, comprising:
- a motor;
- an elevator drive configured to control power supply to the motor, the elevator drive including at least a plurality of converter switches and an energy storage device, the energy storage device being situated to be charged in response to the motor generating a back emf as the motor rotates in response to a torque applied to the motor when the elevator drive is not providing power to the motor;
- and
- a short-circuiting module that is selectively coupled with the energy storage device through the converter switches to selectively discharge the energy storage device to limit the back emf of the motor and a corresponding speed at which the motor rotates.
A method of using an elevator machine to control movement of an associated elevator car, the elevator machine including a motor configured to selectively move the elevator car and an elevator drive configured to control power supply to the motor, the elevator drive having an energy storage device and converter switches, the method comprising:
- determining that a voltage of the energy storage device exceeds a preselected threshold, wherein the voltage of the energy storage device is based on a back emf of the motor rotating when the elevator drive is not supplying power to the motor;
- using the converter switches to couple the energy storage device and a short-circuiting module based on the voltage of the energy storage device exceeding the preselected threshold;
- and
- discharging the energy storage device using the short-circuiting module to maintain the voltage of the energy storage device and the back emf of the motor within respective preselected ranges.
Dependencies are inferred from the claim text.