Fan driving circuit

Patent metadata

Field	Value
Publication number	US-9534611-B2
Application number	US-201313895377-A
Country	US
Kind code	B2
Filing date	May 16, 2013
Priority date	Mar 18, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

A fan driving circuit drives a first fan and a second fan which are connected in parallel and connected to an anode of a direct current power. The fan driving circuit includes a pulse width modulation signal generation module, a phase lock and delay module, a first pulse output comparator and a first capacitor. The width modulation signal generation module is connected between an external power and the first fan. The phase lock and delayed module is electrically connected to the pulse width modulation signal generation module. The first capacitor is connected between the DC and the ground. The first fan is supplied as normal by a PWM power supply, the second fan is powered by “shadow” and out-of-phase pulses taken from an inductor in the first fan and stored in the capacitor, to achieve a “two-for-one” power supply aspect, which saves power and reduces operational noise.

First claim

What is claimed is:

1. A fan driving circuit to drive a first fan and a second fan, the first fan and the second fan connected in parallel and both electrically connected to an anode of a direct current (DC) power, the fan driving circuit comprising:
a pulse width modulation signal generation module that generates pulses to drive the first fan and the second fan; a first terminal of the pulse width modulation signal generation module electrically connected to an external power, a second terminal of the pulse width modulation signal generation module electrically connected to the first fan and the second fan;
a phase lock and delay module electrically connected to the pulse width modulation signal generation module, the phase lock and delay module sending pulse width modulation signals to the pulse width modulation signal generation module to make the pulse width modulation signal generation module generate different phase waves;
a first pulse output comparator comprising a first pulse output comparator first input, a first pulse output comparator second input and an first pulse output comparator output, wherein the first pulse output comparator first input is electrically connected to the phase lock and delay module to receive the pulse width modulation signals generated by the pulse width modulation signal generation module, the first pulse output comparator second input receives a reference voltage, and the first pulse output comparator output is electrically connected between the second fan and ground, wherein the first pulse output comparator sends pulses to the second fan according to the pulse width modulation signals; and
a first capacitor electrically connected between the anode of the DC power and the ground;
wherein the fan driving circuit uses an inductor of the first fan to generate a Lenz current when the pulse width modulation signal generation module is in a non-working cycle, wherein the Lenz current is stored in the first capacitor and is used to drive the second fan;
wherein the pulse width modulation signal generation module comprises a second capacitor with a first end and a second end, and a voltage comparator with a voltage comparator first input, a voltage comparator second input and an voltage comparator output wherein the voltage comparator first input is electrically connected to the external power, the voltage comparator second input receives a reference voltage, the voltage comparator output is electrically connected to the first fan and the first end of the second capacitor, and the second end of the second capacitor is electrically connected to the external power.

2. The fan driving circuit of claim 1 , wherein when an external voltage of the external power is greater than the reference voltage, the voltage comparator output outputs a high level signal to the pulse width modulation signal generation module, and the pulse width modulation signal generation module generates positive wave to make the pulse width modulation signal generation module start working; and
when the external voltage of the external power is less than the reference voltage, the voltage comparator output outputs a low level signal to the pulse width modulation signal generation module to make the pulse width modulation signal generation module be in the non-working cycle.

3. The fan driving circuit of claim 1 , wherein the phase lock and delay module, electrically connected to the pulse width modulation signal generation module, generates the pulse width modulation signals with a phase difference of 180 degrees to the pulse width modulation signal generation module.

4. The fan driving circuit of claim 2 , further comprising a third capacitor and a resistor, wherein the third capacitor is grounded, the resistor is electrically connected to the second capacitor, the third capacitor and the resistor collectively form a filter circuit that converts triangle waves outputted by the pulse width modulation signal generation module to square waves to drive the first fan and the second fan.

5. The fan driving circuit of claim 2 , further comprising:
a third fan, connected in parallel with the first fan and the second fan, and electrically connected to the anode of the DC power; and
a second pulse output comparator, that outputs pulse to drive the third fan, comprising a second pulse output comparator first input, a second pulse output comparator second input and a second pulse output comparator output, wherein the second pulse output comparator first input is electrically connected to the phase lock and delay module, the second pulse output comparator second input is electrically connected to the pulse width modulation signal generation module, and the second pulse output comparator output is electrically connected to the third fan.

6. The fan driving circuit of claim 5 , wherein the phase lock and delay module electrically connected to the pulse width modulation signal generation module, generates the pulse width modulation signals with a phase difference of 120 degrees to the pulse width modulation signal generation module.

7. The fan driving circuit of claim 5 , further comprising a first switch, a second switch and a third switch, wherein a first switch first terminal, a second switch first terminal and a third switch first terminal are respectively connected to the first fan, the second fan and the third fan, a first switch second terminal, a second switch second terminal and a third switch second terminal are all grounded, wherein a first switch control terminal, a second switch control terminal and a third switch control terminal are respectively connected to the voltage comparator output, the first pulse output comparator and the second pulse output comparator;
wherein when the pulse width modulation signal generation module outputs positive waves, the first switch control terminal is a high level, the first switch turns on, and the first fan starts working;
wherein when the pulse width modulation signal generation module stops working, the first switch control terminal is a low level, the first fan stops working, the inductor of the first fan generates the Lenz current when the pulse width modulation signal generation module in the non-working cycle, wherein the Lenz current is stored in the first capacitor and is used to previously drive the second fan.

8. The fan driving circuit of claim 7 , wherein the first switch, the second switch and the third switch are N-type metal oxide field effect transistors, wherein the first switch first terminals, the second switch and the third switch are drains of the N-type metal oxide field effect transistors, the first switch second terminals, the second switch and the third switch are the N-type metal oxide field effect transistor sources, the first switch control terminals, the second switch and the third switch are the N-type metal oxide field effect transistors gates.

Assignees

• Hon Hai Prec Ind Co Ltd

Inventors

• Tai Ming-Tse

Classifications

• F04D25/166 Primary

  using fans · CPC title

• F04D25/0693

  Details or arrangements of the wiring · CPC title

• F04D27/00

  Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids · CPC title

• H02P7/00

  Arrangements for regulating or controlling the speed or torque of electric DC motors · CPC title

• F04D25/16

  Combinations of two or more pumps {; Producing two or more separate gas flows} · CPC title