Control of an elevator hoisting motor during under voltage conditions in the main power source
US5229558A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 31, 1990 |
| Grant date | Jul 20, 1993 |
| Priority date | — |
| Expiry date | Oct 31, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B1/30
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A method and an apparatus for the control of an elevator a.c. or d.c. hoisting motor driven by a frequency converter unit, or by a rectifier unit, supplied by a three phase power source is disclosed. The voltage of the mains power source is monitored using a voltage measuring unit. The frequency converter or rectifier is supervised by a control unit which selects a speed reference curve, best suited for a run. The controller unit allows the elevator speed to be varied continuously with the mains voltage so that the elevator always travels at the highest possible speed. When an undervoltage condition is detected in the mains power source, the rotational speed of the hoisting motor is reduced without modifying the acceleration so as to avoid an overcurrent if the rectifier or inverter switches. If, in addition, the acceleration is decreased before the maximum speed is obtained, a higher maximum speed may be obtained for a given low level of supply voltage. The solution offered by this invention enables the elevator system to work at undervoltages as low as 60%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.