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Current limiting using PWM control

a current limit and control technology, applied in power supply lines, power conversion systems, instruments, etc., can solve the problems of difficult replacement of fuses and relatively expensive circuit breakers, and achieve the effect of limiting current using

Active Publication Date: 2007-06-21
DELL PROD LP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But circuit breakers are relatively expensive and fuses are difficult to replace once the over-current conditions are cleared.

Method used

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  • Current limiting using PWM control
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  • Current limiting using PWM control

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Embodiment Construction

[0013] While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.

[0014] An embodiment of the present invention relates to a system and a method for current limiting using Pulse Width Modulation (PWM). Another embodiment of the present invention relates to the controlling of the current to a fan independent of the master PWM signal. More generally, the embodiments of the invention are applicable to any DC motor or DC-to-DC power supply.

[0015]FIG. 1 is a view of a system 100 that limits current using PWM control, in accordance with an embodiment of the present invention. System 100 comprises a current sensing circuit 102, an over-current comparator circuit 104, a low-pass fi...

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PUM

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Abstract

A method and a system for current limiting using PWM control have been provided. The method includes sensing a load current to produce a control voltage. The control voltage is compared with a reference voltage to produce a detected output signal. Thereafter, the detected output signal is delayed and multiplied with a master PWM signal.

Description

BACKGROUND OF THE INVENTION [0001] Controlled voltage power supply circuits can commonly be regulated but, regulation arrangements in variable power supply circuits are typically not able to provide adequate protection against over-current or short circuit conditions. One such circuit protection problem relates to fan start-up conditions that impact variable power supply requirements. The current drawn by fans at their start-up can be much greater than the normal current drawn for operating. Moreover, for those types of fans that are hot-swappable or are connected with cables, protection for a situation of over-current is required for both safety as well as equipment protection reasons. FIELD OF THE INVENTION [0002] The present invention relates, in general, to limiting current in electronic devices and more specifically to current limiting in electronic devices, such as DC motors used with fans, by using Pulse Width Modulation (PWM) techniques. DESCRIPTION OF THE RELATED ART [0003]...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G05F1/00
CPCH02M1/32Y10S323/908
Inventor COX, STANLEY
Owner DELL PROD LP