Method and apparatus for operating polyphase DC motors using a PWM chopping signal in zero crossing determination
US5517095A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 28, 1995 |
| Grant date | May 14, 1996 |
| Priority date | — |
| Expiry date | Feb 28, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/182
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and circuit for operating a polyphase dc motor having a plurality of driving coils is presented. In one of the available operating modes, drive current supplied to the driving coils is chopped, in PWM fashion to control the maximum current delivered thereto by turning the drive current on and off. Zero crossings of a back emf voltage of the driving coils that are connected into a floating state are detected for producing a commutation signal, and the detection of zero crossings is inhibited for a predetermined time after the drive current is turned off during the chopping step to avoid detecting a false zero crossing. In normal operation, detected back emf sampled voltages are forwarded to back emf detection circuitry responsive to a high frequency clock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.