Apparatus and methods for controlling induction motors
US4800326A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 6, 1986 |
| Grant date | Jan 24, 1989 |
| Priority date | — |
| Expiry date | Jun 6, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P80/10
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
When induction motors are lightly loaded their power factors and efficiency are poor but in the present invention power factor is controlled regardless of load. An induction motor is connected by way of a triac to a supply. The voltage across the triac is monitored by a comparator for voltage steps which correspond to current turn-off and a signal is developed at the output of an amplifier which represents error from required phase lag. A further comparator and a trigger pulse generator trigger the triac in accordance with the error. An override circuit overrides the control system during starting. A number of further induction motors may be connected in parallel with the motor. Additional circuits deal with problems arising when a three-phase induction motor is connected by three wires only.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.