Reversible variable frequency oscillator for smooth reversing of AC motor drives
US4227138A · kind A · utility
30Cited by
7References
11Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 10, 1978 |
| Grant date | Oct 7, 1980 |
| Priority date | — |
| Expiry date | Apr 10, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P27/045
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A variable speed ac motor drive such as a controlled current inverter drive with load angle control generates an inverter frequency command signal which at low speed has a large ripple component and a small dc component representing the desired frequency. A variable frequency oscillator is responsive only to the dc component and supplies timing pulses to a ring counter which generates thyristor gating signals in the forward and reverse phase sequence. Smooth reversing over a wide range of torque is realized, and multipulse operation is inherent at low speeds to modulate the inverter output and minimize cogging torque.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.