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Method and System for Controlling Speed of fans using Phase Shifted Pulse Width Modulated (PWM) Signals

IP.com Disclosure Number: IPCOM000249541D
Publication Date: 2017-Mar-03
Document File: 2 page(s) / 38K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for controlling speed of fans using phase shifted pulse width modulated (PWM) signals. The method and system separates pulses or PWM signals between each of the fans to reduce a noise spike.

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This is the abbreviated version, containing approximately 56% of the total text.

1

Method and System for Controlling Speed of fans using Phase Shifted Pulse Width Modulated (PWM) Signals

In a server and server type applications, fans draw power through multiple boards that may be sensitive to a noise spike. In order to reduce the noise spike, speed of fans is controlled in the server and server type applications by providing pulses to the fans. Providing the pulses to the fans turns on and off a power that is provided to the fans which causes voltage spike or noise spike to be produced on input power feeds of the fans. In a system with multiple fans, a large noise spike may be created as pulses provided to the multiple fans are driven together and the rotational speed of the multiple fans line up.

Disclosed is a method and system for controlling speed of fans using phase shifted pulse width modulated (PWM) signals. The method and system separates pulses or PWM signals between each of the fans to reduce a noise spike.

The method and system provides a separate PWM signals to each fan by driving all PWM signals with a same duty cycle and frequency. The same duty cycle and frequency maintains a same speed and functionality of the each fan. Each PWM signal is driven with a phase offset from other fans that ensures that a positive going edge on one PWM signal never lines up with a positive edge going on another PWM signal.

FIG. 1 illustrates an example of PWM signals with different frequencies and same phase.

FIG. 1

As illustrated in FIG. 1, the method and sys...