Ac motor drive with switched autotransformer coupling
US4935686A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 18, 1989 |
| Grant date | Jun 19, 1990 |
| Priority date | — |
| Expiry date | Aug 18, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P1/46
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An ac drive in which the three phase ac current produced by a current controlled inverter is applied to the stator winding of a synchronous or induction motor through an autotransformer equipped with a neutral shorting switch. For starting from zero speed and operation at very low speeds below the speed at which the autotransformer could provide adequate volt-seconds for operation of the motor, the neutral shorting switch is opened so that the current is applied essentially directly to the stator. At normal and high speeds, the neutral shorting switch is closed so that the voltage to the motor stator is increased by the turns ratio of the autotransformer thereby increasing the speed range of the motor. By providing a number of sets of taps on the autotransformer each with a neutral shorting switch, the ac drive mimics the characteristics of a drive with a multi-ratio gear box.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.