Back EMF sampling circuit for phase locked loop motor control
US4928043A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 14, 1988 |
| Grant date | May 22, 1990 |
| Priority date | — |
| Expiry date | Nov 14, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/182
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A sensorless control for DC permanent magnet brushless motor includes a feedback loop connected between the motor stator windings and the inverter which controls the timer at which current is provided to the various windings in sequence. The control of the invention includes a voltage sensing network for sensing the back EMF on each motor winding when it is unenergized and comparing this voltage with a null point. For maximum torque this voltage has an optimum value and variation from this value produces an error signal which is integrated to produce a VCO drive signal. This signal controls the frequency of a VCO which in turn controls the switching times of the inverter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.