Method and apparatus for starting a sensorless polyphase DC motor in dual-coil mode and switching to single coil mode at speed
US5455885A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 13, 1995 |
| Grant date | Oct 3, 1995 |
| Priority date | — |
| Expiry date | Feb 13, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/21
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for operating a polyphase dc motor selectively in dual-coil or uni-coil commutation modes. The motor has a plurality of "Y" connected driving coils connected together at a center tap. Each driving coil has an input node at an end opposite the center tap, and is driven by a switch pair. Each switch pair is arranged for connection in series across a power supply voltage, and has a node between each switch connected to a respective one of the coil input nodes. An additional pair of switches are provided for connection in series across the power supply with a connection node between each switch connected to the center tap. A circuit is provided to operate the switches to cause a driving current to be passed between sequentially selected pairs of the driving coils for an initial start-up time. Also, a circuit to operate the switches after the initial start-up time is provided to cause a driving current to be passed between sequentially selected only single ones of the driving coils and the center tap current input node. The apparatus also has a circuit for detecting a zero crossing of a bemf signal of a floating one of the driving coils and a delay circuit for est…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.