PWM radiator fan control

Testing and development of Megasquirt 3

Moderators: jsmcortina, muythaibxr

Post Reply
silvermonster
MS/Extra Newbie
Posts: 1
Joined: Wed Nov 09, 2016 9:41 am

PWM radiator fan control

Post by silvermonster »

I am trying to get my new ms3pro (firmware 1.4.1) to control my radiator fan on my 1990 mustang (and the running of the engine too). I know that Tuner studio can control the fan with a simple on and off configuration, but I was trying to get the ms3 to PWM the fan control based on coolant temp. When the car is off, fan off. When car is running turn on the fan and control the fan speed based on the coolant temp. So if the engine is cold the fan is off, as the coolant temp starts to increase, the fan will start at a slow speed and as the temp continues to rise, have the fan speed try to maintain that temp until it gets to full speed. Ideally I want to try to target about 200 degrees with varying the fan speed. I am thinking this can use some sort of feedback loop to vary the fan speed. I am using a ford mark 6 fan, it has a very large inrush current when it cycles on and off, so if I can PWM the fan it should limit this inrush current. The "Fan control" feature of tuner studio only allows for on and off of the fan control not PWM control. The generic PWM outputs under "Advanced engine" only allow for one axis to be load (for me coolant) and the other is not changeable and is only referenced to RPM. Ideally I want one axis to be coolant temp the other to be Load output which is directly related to fan speed. So at low coolant temp, low load (slow fan) and at high coolant temp high load (fast fan). I hope this makes sense, this would be a great feature to add to the MS3 Pro. I know there are specific PWM fan controllers on the market but I strongly think that MS3pro can do this with the correct programming, the only thing you would have to buy is a solid state relay to handle the large current of the fan. I have found that a 2000's Dodge Caravan has a solid state relay in it for this function and is cheap at a salvage yard!! Any help would be greatly appreciated. Thanks, Scott
aidandj
Experienced MS/Extra'er
Posts: 255
Joined: Fri Sep 26, 2014 1:38 am

Re: PWM radiator fan control

Post by aidandj »

Someone on another forum recently looked into this. They called a fan manufacturer and found out that fans should be PWM'd at a much higher frequency than the MS3 supports. In the kHz range instead of just 200Hz.
acedeuce802
Helpful MS/Extra'er
Posts: 47
Joined: Mon Sep 29, 2014 5:57 pm

Re: PWM radiator fan control

Post by acedeuce802 »

http://jbperf.com/pwm_converter/index.html

This will allow higher frequencies. I plan to use this and a solid state relay to control a Taurus fan with closed loop control.
stevevp
Helpful MS/Extra'er
Posts: 40
Joined: Fri Nov 11, 2011 3:43 am
Location: Brisbane, Australia
Contact:

Re: PWM radiator fan control

Post by stevevp »

Mercedes and GM (Corvette C6) fan controllers by Siemens

photo here http://www.frankencis.com/Forum/aft/32

Mercedes units have ignition and PWM signal lines

Corvette just has the PWM

Both have very high current ratings and include soft start of the fan by default

~100hz signal ground switched between 10% and 90% duty on the PWM line is all that is needed for the Corvette unit

The Mercedes required 12v to the ignition terminal, and ~100hz signal ground switched between 10% and 90% duty on the PWM line

10% is off on both
90% is full speed on both
values between 15% and 90% produce a variable speed relative to the signal

if no PWM signal found on the Mercedes unit and ignition is on it will go into a full speed failsafe mode

The Mercedes unit could be run with just the ignition signal as a basic soft start fan controller
Steve
krisr
Master MS/Extra'er
Posts: 799
Joined: Wed Aug 17, 2005 1:17 am
Location: Sydney, Australia

Re: PWM radiator fan control

Post by krisr »

Generic PWM table could be used to drive a PWM coolant fan with one axis being clt obviously and the other being VSS. That's how I'd do it.
Sydney, Australia
1971 Holden Monaro HQ
MS3X Sequentially fuelled 400 Pontiac
whittlebeast
Super MS/Extra'er
Posts: 2221
Joined: Tue May 04, 2004 8:20 pm
Location: St Louis
Contact:

Re: PWM radiator fan control

Post by whittlebeast »

stevevp wrote:Mercedes and GM (Corvette C6) fan controllers by Siemens

photo here http://www.frankencis.com/Forum/aft/32

Mercedes units have ignition and PWM signal lines

Corvette just has the PWM

Both have very high current ratings and include soft start of the fan by default

~100hz signal ground switched between 10% and 90% duty on the PWM line is all that is needed for the Corvette unit

The Mercedes required 12v to the ignition terminal, and ~100hz signal ground switched between 10% and 90% duty on the PWM line

10% is off on both
90% is full speed on both
values between 15% and 90% produce a variable speed relative to the signal

if no PWM signal found on the Mercedes unit and ignition is on it will go into a full speed failsafe mode

The Mercedes unit could be run with just the ignition signal as a basic soft start fan controller
Very cool idea.

James, can we drive that thing? Electric water pumps, fuel pumps, cooling fans, traction control devices, electric power steering.... Who knows???

Andy
Laminar
Master MS/Extra'er
Posts: 644
Joined: Wed Aug 06, 2014 7:45 am

Re: PWM radiator fan control

Post by Laminar »

I pulled a fan shroud/controller off a Lincoln Zephyr at the junkyard and it had this module on it.

Image

Given that I want to be able to utilize MS's fan control features, I don't think I want to use a generic PWM output for this. I'm currently using INJ1 as a ground switch to my fan relay. What would happen if I instead connected that to the module's PWM input and grounded the PWM input. I'm assuming it'd see 100% duty cycle and the fan would run at full speed - is this a good assumption?
Post Reply