Speed reducing control system with voltage regulation for a polyphase electric motor
US4524316A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 11, 1983 |
| Grant date | Jun 18, 1985 |
| Priority date | — |
| Expiry date | Oct 11, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/7072
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A variable speed 3-phase a-c motor is connected via a plurality of controllable bidirectional switches to a 3-phase source of alternating voltage having a variable fundamental frequency (f) and an rms magnitude (v) that varies with f, and the switches are suitably arranged and controlled so that motor speed can be reduced by skipping selected cycles of the source voltage. When operating at a fraction of full speed, the magnitude-to-frequency ratio of motor voltage is maintained substantially the same as at full speed by varying the "firing angle" at which the switches start conducting current so as to minimize any deviation of the rms magnitude of the motor voltage from the product of v times said fraction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.