Design of a fan controller

Hi all I am new to this group. I am pursuing my masters in electrical engineering. I have opted a control systems course in which I am facing
difficulties. I am doing a small project to design a fan controller like a cooling system present in the cars. I am not good at designing the control systems. I want design it in Matlab/simulink I am good at simulink. I have a block diagram which gives the idea for the project. Can any one help me out in getting started with the cotroller design and what more specifications should I consider for the design. ( this doesn't allow me to post the block diagram) The basic working of the cooling system is, initially the cold water/coolant flows from Radiator through the water pump and gets warmed passing through the oil cooler and flows through the engine where it gets heated. An electric thermostat is used to by pass the water either into radiator where the coolant is cooled by a electric fan (20kw, 2000rpm) and is cycled back into engine through the water pump and oil cooler, the thermostat may also block the flow of coolant to the radiator and directly send into the water pump if the engine is below the operating temperature and when it reaches the operating temperature the thermostat opens and the coolant is passed through the radiator allowing it to cool down. Theere are temperature sensors that reads the temperature one located at the outlet of engine before the thermostat and second one after the water pump and third one after the oil cooler these allows us to design the controller for the model. The electric fan is variable speed fan and its speed is controlled by the speed command The position of thermostat and speed command for the fan is PWM signal (0-100% duty cycle)
Given Requirements 1.    Cooling fan mounted between radiator and engine (20 kw, 2000rpm) 2.    The performance of the fan would be same for the both directions 3.    The coolant temperature should be between 120 c to 140 c 4.    Max engine outlet temperature is 110 5.    Max radiator inlet is < 104 c and delta T across rad is 8 c 6.    Oil temperatures around 70 c to 100 c (Max temp allowed is 113 C) 7.    Air temperatures (predicted exiting the radiator) app 80 c 8.    Max heat sink temp <70 c 9.    Max ambient temperature within cool box : 85 c 10.    Min ambient temperature within cool box -40 c 11.    Flow of the coolant can also be controlled by the speed of the water pump
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And this has WHAT to do with model rocketry exactly?

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R & K Bilyea wrote:

Sometimes we'll get a strange post like this when the poster thinks "models" refer to a mathematical description of some process or thing. He's looking for a model (description) of a control system, not a model (thing).
Sometimes they think models are girls in swimsuits. ;)
--
Gary Bolles

summum jus, summa injuria est
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Freck, and for 35 years I've been doin' models and ..... they are 'sposed to ware swimsuits ?
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AlMax wrote:

Don't worry about it too much, there's some definite advantages to your method. I've found that naked models are easy, quick to finish, and perform well in competitions.
(10 to 1 this will be the post that one my students brings in on Monday)
--
Gary "Quittin while he's ahead." Bolles

summum jus, summa injuria est
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NOTHING, but more "usenet compliant" than most of the rants by Dave Grayvis, Phil Stein, Ray Dunakin and others.

--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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wrote:

We own you Jerry. You can't stop thinking about us. Now quite jijacking this guy's thread. If you want, you can start your own. Then when you start your usual bs & you can get flamed - just the way you like it.
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As mentioned above, you might want to try posting this in sci.eng.mech or something similar.
As a pointer in the right direction, sounds like you'll need a P (proportional), PD (proportional-derivative), or a PID (proportional-derivative-integral) controller. P controllers are the most simple, as their output is solely dependant on the difference of "where you want to be" to "where you are". As an example, say you want your radiator to maintain a coolant temp of 200F. A P controller could control the PWM output according to a function like:
PWM_out=K*(T_actual-200)+PWM_baseline
where PWM_out is the output PWM, K is a scalar to get a duty cycle value, T_actual is the actual temperature of the coolant, and PWM_baseline is the PWM you want to maintain if the coolant is exactly 200F (i.e. you don't want to turn the fan off).
Dave
kumarkk wrote:

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