DC Motor Control from ECU ???
Turbo Mini Forums

Colin,

Please try to stick with metric, it's what we work in as engineers, I have to get my calculator out when you quote "1.5hp".....

Your figures are correct but I guess the point Paul is trying to show is that it doesn't need 1.12KW to circulate an adequate amount of water through the engine with a reasonably designed impellor.

If it really requires 1.12KW then how do the aftermarket pumps with really crap impellor designs actually work ???

I've worked on some fairly big pumps in my time - 6 MegaWatt ones pumping 5 tonnes per second at 155bar - so I know what a proper impellor and inlet diffuser looks like.

Rod.

Schrödinger's cat - so which one am I ???

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Hi Sprocket
My thoughts on your subject
Use the existing mini parts as you basis
For the design
I.e physical pump size and speed (we know this or it is easy to work out) apply motor speed or faster to the model to increase cooling if required
I would use a speed controller from a electric model car as some of these are now running 750 amps duty cycle or more on 7.4 volts (my son races internationally)
You would need to input a common radio control signal to the speed controller which can be programmed to suit your requirements via a laptop
Hope this helps
Jawd

Something LIKE this

Www.hobbywing.com

Edited by Jawd on 11th Nov, 2013.

We have one of those cars, the amps they draw is beyond belief. However, the circuits are overkill and do not interface with what I'm trying to do.

At the most, the pump needs to push at a maximum of 1 litre/second. No need to pump any more as the radiator will not perform any better if you do.

Assuming that the head loss through the system is, at worst, 1 Bar, then the water power needs to be 100W. Taking into account pump and motor efficiency then we are probably talking around 250W electrical power, approx. 20A depending on voltage. This follows others experience using the Meziere pump.

The maximum capability of the motor has no bearing on the amps required to drive the pump. However, the big motor will need a "kick" to get it rolling, so I expect to have to put some high duty cycle numbers in the table, just above idle, so that a quick blip of the throttle, once running, will get the pump turning.

Latest schematic based on using a spare injector output:



The biggest cost of this is going to be the enclosure and connectors. The component cost is beer money.

Edited by Paul S on 11th Nov, 2013.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

is using a starter motor a good idea?

I'm thinking in terms of turns per volt ratio and magnetic core flux density... if these are both quite low will this not be inefficient.

could there be an issue where you find you have a sudden point where the motor turns on and goes above the required output?

basically should you be looking at a motor of a more suitable size.

Let's be clear that this motor is nothing like a conventional mini starter motor. The Toyota starters are internally geared at about 4:1. They must run up to about 8000rpm to crank the engine over at 200rpm.

The motor itself is quite small at only 65mm diameter.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

On 10th Nov, 2013 Sprocket said:

Rod, as an Engineer you should be able to work with any type of unit Its just convenient to use one or the other which sometimes just is not the case. Complain about it or get on with it, it's still the same thing.

Edited by Rod S on 11th Nov, 2013.

Schrödinger's cat - so which one am I ???

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

OK, so before I start cutting metal to make the motor mount, can anyone recommend a suitable motor, at least 500W and 5000rpm.

Or would I have more success looking for hen's teeth????

Edited by Paul S on 12th Nov, 2013.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Schrödinger's cat - so which one am I ???

Thanks Rod.

Right, off I go, G-Code in hand.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

No going back now

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Good start...

Although I'm not familiar with MS3, I assume you can log the PWM generated value as well as all the others from the engine based on your table.

If so, it should soon be obvious what the actual power required is.

Looking at the Meziere website (that Evoderby first mentioned) it seems they can cool a few zillion horsepowers with just under 20 Amps and some flowrate in units that Colin would need to explain to me (.....only joking Colin).

From their pictures I would think the motor they use is a permenant magnet type. The motor you've pulled out of a starter motor is 99% sure to be series wound.
Torque vs current characteristics are different from what I remember (most of my best knowledge is obviously 3 phase AC and large) but I still don't think it will be a problem at your anticipated low power level.

But once you know the actual power (from the PWM) it would be easy to choose an alternative motor if required.

From a mechanical point of view, I think your biggest loss will be with a Vee belt drive.

If this works out I would suggest switching to a small, thin and narrow polydyne Vee. Machine your own pulleys.

Schrödinger's cat - so which one am I ???

Paul
I would look at adapting a brushless motor and speed controller from the latest RC Cars and perhaps using a reduction gearbox to drive the existing mini waterpump.
A small device to convert a ECU signal to a signal the speed controller needs would be very simple to build.
But good luck with your project which I will watch with great interest
Jawd

Slight change of plan.

The MS mainboard I'm planning on using was built without the injector drivers. I've got all the components to add the injector circuits from the original kit, but there is about 30 of them

So, I'm going to use a MS3X output instead and will add the extra transistor and resistor to the controller circuit:



Rod, as you say, we should be able to get a idea of the power requirement from the duty cycle. We will need some long private roads to get some steady state conditions at high speed to dial it all in though

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,

The MS3X PWM outputs are ground switching outputs that can handle more current that a ZTX450 (up to 3A). So you can go back to the previous diagram (actually you'd need a pull up resistor if you wanted to use the NPN transistor with the MS3X outputs).

Jean

http://www.jbperf.com/

Bracket/End Cover now finished:



Parcel Farce just delivered a package of electrickery bits

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

THAT is a nice bit of bracketry!

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Schrödinger's cat - so which one am I ???

Sorted now. I was milling off the copper then drilling.... not good.

Drilled first and then milled off the copper. No problem. Then realised that I did not need to mill off all the copper.......Doh.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Circuit built:



Some nice thick copper bus-bars run from the connectors to the MOSFETs.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."