Thyristor Leonard type elevator control system
US4399892A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 9, 1981 |
| Grant date | Aug 23, 1983 |
| Priority date | — |
| Expiry date | Sep 9, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P23/0077
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The disclosed elevator control systems comprises a three-phase AC source and an emergency three-phase AC generator supplying selectively an AC power to a thyristor Leonard type converter connected to a hoist DC motor for driving an elevator car, and a firing control circuit formed of a microcomputer. With the converter connected to the AC source, the microcomputer calculates a firing signal from a command and an actual speed signal for the hoist motor, and an input current to the converter according to a firing program stored in it and delivers the firing signal to the converter to control its firing in the symmetric mode. Upon a suspension of the AC power, a power failure detecting relay drops out to connect the converter to the emergency generator, decrease the command speed signal and cause the microcomputer to calculate similarly a firing signal but by using the decreased command speed signal and another firing program stored in it. The firing of the converter is controlled in the unsymmetric mode according to that firing signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.