Method of controlling start-up noise in BLDC (brushless direct current) fan motors
US9853580B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 2014 |
| Grant date | Dec 26, 2017 |
| Priority date | — |
| Expiry date | Jun 27, 2034 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF04D25/0613
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method to reduce acoustic noise in a cooling fan motor is disclosed. The method includes reducing the slew rate of a PWM (pulse width modulation) voltage waveform applied to energize a coil of the fan motor. This slew rate reduction results in lower mechanical vibrations and acoustic noise in the fan motor. In one embodiment, the slew rate reduction is performed during startup of the fan motor, when the motor is spinning slowly and there is little air flow noise. In another embodiment, the slew rate reduction is not performed during high speed operation of the fan motor, when the fan motor is spinning very fast and air flow noise masks the motor noise. In one embodiment, there is variable slew rate control depending on the speed of the fan motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.