Hydraulic elevator control apparatus using VVVF to determine the electric drive motor rotational speed
US5131507A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 13, 1990 |
| Grant date | Jul 21, 1992 |
| Priority date | — |
| Expiry date | Jun 13, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B1/30
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A hydraulic elevator control apparatus comprises an induction motor for driving a hydraulic pump which sends and receives a fluid, an inverter circuit for determining the number of rotations of the induction motor using variable-voltage variable-frequency, and a speed control apparatus which detects the voltage and current of the induction motor, calculates the number of rotations of the induction motor on the basis of the detected voltage and current, and controls the inverter circuit on the basis of the calculated number of rotations. The speed control apparatus comprises a current transformer for detecting the primary current of the induction motor, a voltage detector for detecting the primary terminal voltage of the induction motor, a magnetic-flux torque calculator for calculating a torque current calculation value and a magnetic-flux amplitude calculation value from the detected primary current and primary terminal voltage, and a frequency controller for calculating the speed calculation value on the basis of the difference between the torque current command value and the torque current calculation value calculated by the magnetic-flux torque calculator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.