Method to detect the true zero-crossing points of the phase back EMF for sensorless control of brushless DC motors
US6879124B1 · kind B1 · utility
Inventors
Key dates
| Filing date | Jan 7, 2004 |
| Grant date | Apr 12, 2005 |
| Priority date | — |
| Expiry date | Jan 7, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/187
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In the present system and method, ZCP level signals of each phase voltage are first obtained. Among the detected ZCP level signals, some ZCPs are generated by phase back EMF, which are true ZCPs and other ZCPs by commutations, which are false ZCPs. The duration of the false ZCP level outputs varies with the excited phase current, inductance and back EMF of motors, the present invention utilizes fixed-width narrow pulse signals corresponding to the rising and falling edges of the ZCP level outputs in order to eliminate influences of the earlier disclosed motor parameters. These fixed width pulse signals make up the ZCP pulse signal. Because the first edge of the plurality of false ZCP level signal substantially corresponds to the switching-off signal of the commutated-off excited phase, a first false ZCP masking signal having pulses wider than the ZCP pulse signal are applied to mask the first plurality of false ZCP signals. Comparing the logic values of the ZCP level signals, the pulses of the ZCP pulse signals are identified as true ZCPs when the logic values of the current pulse are different from the logic value of a preceding pulse. Correspondingly, if the logic value of the cu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.