Variable speed a-c drive
US4814964A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1988 |
| Grant date | Mar 21, 1989 |
| Priority date | — |
| Expiry date | Jan 27, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P25/024
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A load commutated inverter (LCI) a-c drive system includes a synchronous motor with two 30 degree angularly displaced sets of three-phase windings. Each set of motor windings is powered by a three-phase inverter fed by a three-phase rectifier in a separate d-c loop. The three-phase rectifiers are fed by either a generator with two angularly displaced sets of three-phase windings or by a transformer with a three-phase primary winding, and delta and wye secondary windings separately supplying the two rectifiers. Twelve-pulse operation in the line commutated mode with substantially constant d-c link currents significantly reduces torque pulsations. At low speeds, sinusoidal segment pulsed d-c currents in the d-c links are gated to pairs of windings in the two sets of motor windings which generate component MMFs either 90 degrees or 150 degrees displaced to produce a resultant rotating motor MMF of constant magnitude to completely eliminate torque pulsations. Since the repetition rates of the pulsed d-c link currents in these two instances are 2 and 1.2 times the fundamental motor frequency respectively, the range of motor speeds over which torque pulsations can be completely eliminate…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.