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P.H.A.N.S
PWM HUB AIR-COOLED NOISE-REDUCTION SYSTEM
GROUP MEMBERS: ADAM PALERMO, BRIAN HANSEN
FACULTY ADVISOR: DR. ARASH TAKSHI
INDUSTRY ADVISOR: DANA RODAKIS
Introduction

Adam Palermo, 25, Test Support Engineer I, Raytheon employee for
over 5 years

Brian Hansen, 33, Field Engineer II, Raytheon employee for over 7
years
SCOPE
Objective:

Establish the electrical specifications, software algorithm behaviors,
and platform requirements of P.H.A.N.S.
Non-Objective:

Specify mechanical performance and hardware dimensions of
P.H.A.N.S.
Problem Statement
Root-Cause Analysis

PC case cooling fans on a high performance system can be noisy. Why?

They are operating at ‘full throttle’ at all times. Why?

There is no system to control the speed of the fans based on the
temperature of the PC. Why?

Most motherboards do not support temp/speed control of multiple (x10)
PC fans. How do I fix this problem?

Buy a COTS system or design a stand-alone temperature-proportional fan
speed control system.
Overview

Modular temperature-proportional fan speed controller

Offers acoustic noise reduction

Efficient PWM fan drive

Fault detection circuitry

Operational data via a LCD digital display to the user
Proposed Design

Independent control per zone (5 Zones)

Temperature and fault sensing at each
zone

PWM fan speed control provided by
microcontroller

Control unit with LCD Display module
installed at an unused 5.25 inch expansion
slot.

Menu selectable fan speed, temperature,
duty cycle, and fault data.
Functional Block Diagram
User Interface
Hardware Interface and Control

Industry standard connections

4-Pin Molex peripheral connector

4-Pin Molex CPU fan header

USB type B

Temperature sensor header

LCD display module header
Microcontroller

Arduino MEGA 2560 R3

This project and prototype development module will provide the
entire microcontroller platform. It is based on the Atmel
ATmega2560 and provides 54 digital input/output pins (of which 15
can be used as PWM outputs), 16 analog inputs, 4 UARTS, a 16MHz
crystal oscillator, a USB connection, a power jack, an ICSP header,
and a reset button.
Electrical Specifications
Fan Speed Control Methods
PWM Fan Speed Control (PWM)

Speed control by varying the duty cycle of a
fixed frequency pulse train

Typical fixed frequency 30Hz

Duty cycle: 0% to 100%

Pulse train will drive the gate of an N-channel
MOSFET
Fan Speed Control Methods
Fan Start-up

Fan’s inertia must be overcome at start-up

Cannot apply PWM duty cycle from rest position

Instead, apply full rated voltage to fan for one second
Fan Speed Control Methods
PWM Frequency & Duty Cycle Control

Frequency controlled by software
and internal timers of uP

Duty cycle is proportional to the
temperature

Temperature (VTEMP) read at GPIO of
uP
Fan Speed Control Methods
Minimum Speed

Sets a threshold for a minimum duty cycle

Fan will remain at minimum duty cycle even when the temperature
continues to decrease

Some fans cannot operate below a certain duty cycle
Fan Speed Control Methods
PWMOUT Output

Will drive the gate of a N-channel MOSFET

PWM output will be designed to quickly raise
the gate voltage to final value

When microcontroller is in shutdown mode,
the PWM output is held actively low

When the MOSFET is turned off quickly, the
current in the fan will continue to flow in the
same direction and will cause the voltage at
the drain of the MOSFET to rise above the
drain-to-source voltage rating of the MOSFET.
For this reason, a clamp diode will be used
Temperature Sensor Design

VTEMP range of 0.56 to 4.44 volts

NTC thermistor (RT) provides
temperature variant voltage

Temperature dependent voltage
divider circuit

As temperature increases, value of
RT decreases and the voltage at
the uP GPIO increases

R1 helps to linearize the response of
the sense network and aids in
obtaining the proper voltages over
the desired temperature range
Sensing Fan Operation

SENSE (GPIO) of uP is an analog
input used to monitor fan operation

Senses fan current pulses, which
represent fan rotation

Commutation of the fan current
occurs as the fan pole passes the
armatures of the motor

When a pulse is detected, the
missing pulse detector timer is reset

If the missing pulse detector timer
reaches 32 cycles, the loop for
diagnosing a fan fault is engaged
Sensing Fan Operation

Fan current waveforms can be
sensed using the scheme shown

The fan current flowing through
RSENSE generates a voltage
proportional to the current

The CSENSE capacitor removes any
DC portion of the voltage across
RSENSE and presents only the
voltage pulse portion to the uP

The op-amp will amplify the
waveform to a CMOS level.
Software Behavior Algorithms
LCD Display Module

RioRand LCD Module RRLCD204WB

20 Characters X 4 Rows

Arduino Support
Parts List
Reference Description
R3
R4
Rsense
C2,C3
C5
CR1
Q1
Q2
uC
PCB
XP1
XP2
LCD1
PROTO1
FAN
PS1
CASE
Part Number
Product Materials
Fixed Resistor 5.6k ohm
KOA Speer MF1/4DC5601F
Fixed Resistor 100 ohm
KOA Speer MF1/4DCT52A1000F
Fixed Resistor 1.5 ohm 5W Vishay / Draloric AC05000001508JAC00
Capacitor 0.01uF
Vishay / BC Components K103K15X7RF5TL2
Capacitor 0.1uF
Vishay / BC Components K104K15X7RF5TL2
LED
Vishay Semiconductors TLUR6400
N-channel MOSFET
Supertex TN0702N3-G
Transistor PNP
Fairchild Semiconductor 2N3906BU
Microcontroller Arduino
Mega 2560 R3
Prototyping PCB
BusBoard Prototype Systems PAD1
Header
Molex 47053-1000
Header
Molex 15-24-4449
LCD Module Rio Rand
RRLCD204WB
Test and Prototyping Material
Breadboard, Solderless
400 tie-points, 4 power rails, 3.3 x 2.1 x 0.3in
120mm Cooling Fan
Cooler Master R4-L2S-124K-GP
Power Supply, Case
LOGISYS Computer PS480D 480W ATX12V
Computer Case
DIYPC Gamemax-BK Black
Quantity Price Per Unit Subtotal
5
5
5
10
5
5
5
5
1
1
10
1
1
0.06
0.06
0.42
0.1
0.1
0.12
1.08
0.2
36.88
3.75
0.43
0.83
10.99
0.3
0.3
2.1
1
0.5
0.6
5.4
1
36.88
3.75
4.3
0.83
10.99
1
12
1
1
5.99
1.99
14.99
69.99
5.99
23.97
14.99
69.99
182.89
Total
Dependencies and Assumptions

The user must provide a computer case that can accommodate up
to 10 optional cooling fans

An unused 5.25 inch expansion slot must be available

The computer power supply harness must provide a spare 4-pin
Molex peripheral connector

The computer power supply must support the added power
requirements of the P.H.A.N.S unit as well as any added cooling fans

The user has general computer hardware knowledge or can hire the
services of a professional computer technician to install the system
Test Plan

Identify subsystems & critical components to be tested or not tested

Evaluate risks of above

Develop data collection plan (sample 1 out of 100 widgets?)

Review measurement equipment and capabilities

Construct test procedure

Define pass/fail criteria

Provide troubleshooting guide
Website

https://phansprojectusf.wordpress.com/
Hardware Demo

Removed due to upload size restrictions
Q&A