Brushless DC motor controller
US5929577A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1997 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | Nov 17, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/182
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A brushless DC motor controller including a track and hold circuit responsive to the voltage at the motor centertap terminal and the voltage across at least one motor winding in order to determine the position of the rotor by detecting zero crossings of the back EMF of the unenergized winding in a manner having reduced susceptibility to noise. In one embodiment, the output of the track and hold circuit is interpolated to reduce the effects of pulse width modulation noise on rotor position detection. The drive signals controlling a plurality of electronically controlled switches which effect energization of the windings are chopped in order to control the speed of the motor. In one embodiment, the switch connected to a positive voltage is chopped when the sensed back EMF is positive and the switch connected to the negative voltage is chopped when the sensed back EMF is negative. Also provided is a PWM disable circuit for selectively disabling a PWM signal used to chop the drive signals in order to further reduce the effects of noise on rotor position detection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.