p.h.a.n.s pwm hub air-cooled noise-reduction system group members: adam palermo, brian hansen...
TRANSCRIPT
P.H.A.N.SPWM 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 ListReference Description Part Number Quantity Price Per Unit Subtotal
R3 Fixed Resistor 5.6k ohm KOA Speer MF1/4DC5601F 5 0.06 0.3R4 Fixed Resistor 100 ohm KOA Speer MF1/4DCT52A1000F 5 0.06 0.3Rsense Fixed Resistor 1.5 ohm 5W Vishay / Draloric AC05000001508JAC00 5 0.42 2.1C2,C3 Capacitor 0.01uF Vishay / BC Components K103K15X7RF5TL2 10 0.1 1C5 Capacitor 0.1uF Vishay / BC Components K104K15X7RF5TL2 5 0.1 0.5CR1 LED Vishay Semiconductors TLUR6400 5 0.12 0.6Q1 N-channel MOSFET Supertex TN0702N3-G 5 1.08 5.4Q2 Transistor PNP Fairchild Semiconductor 2N3906BU 5 0.2 1uC Microcontroller Arduino Mega 2560 R3 1 36.88 36.88PCB Prototyping PCB BusBoard Prototype Systems PAD1 1 3.75 3.75XP1 Header Molex 47053-1000 10 0.43 4.3XP2 Header Molex 15-24-4449 1 0.83 0.83LCD1 LCD Module Rio Rand RRLCD204WB 1 10.99 10.99
PROTO1 Breadboard, Solderless 400 tie-points, 4 power rails, 3.3 x 2.1 x 0.3in 1 5.99 5.99FAN 120mm Cooling Fan Cooler Master R4-L2S-124K-GP 12 1.99 23.97PS1 Power Supply, Case LOGISYS Computer PS480D 480W ATX12V 1 14.99 14.99CASE Computer Case DIYPC Gamemax-BK Black 1 69.99 69.99
Total 182.89
Product Materials
Test and Prototyping Material
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
Hardware Demo
Removed due to upload size restrictions
Q&A