Open Source Electric Supercharger

[neutron256]

Originally Posted by Grantmac

This might be review for all you computer savy folk, but I'm thinking these have potential:
http://www.pololu.com/catalog/product/1350
http://www.robotshop.com/absolute-ga...0-400-kpa.html

Keeping in mind that I don't know crap about code, but it seems like it shouldn't be impossible for this controller to read both the TPS and pressure sensor to adjust the ESC to produce a desired amount of boost. This might even possibly be referenced to RPM if you could make that a 0-5v input.

Maybe I'm completely nuts, I'm a mechanical guy and the closest I've ever gotten to electronics was a lot of electric RC as a teen and building/tuning a MS1.

I do however think that optimizing this system requires more than just on/off control. Building enough power into the system to produce good amounts of boost up top will create the problem of too much boost on the bottom end. Unless a person just wants it to fill-in the torque curve while developing a little more up top.

-Grant

Both of those have potential. For a controller ther are probably tons of micro controller options. Lots like the arduino because it has so many different capabilities. For my design since I'm using the unichip all I need is something that can convert a 0-5V signal into a servo signal. I'll probably be using a PICaxe for this since its dirt cheap, and it has very simple built in function for controlling servos.http://www.picaxe.com/

Edit: BTW, I have a pretty good electronics background but at heart I'm a mechanical guy too. Truth is we have lots of people on this thread who seem willing to help on the programming/electronics side, we could use a few more mechanical people.

On a separate note I'm slowly going through the Unichip tuners Manual (769 pages) and learning a lot. I think at least one reason that the Phantom supercharger may be causing a CEL below 3000 RPMs may be because its pushing the MAP sensor above its upper limit. If that's the case it should be possible to clamp that signal and prevent the CEL.

[Grantmac]

Originally Posted by Calum

Grant, the problem is what do you adjust on the ESC in order to control it without loosing a ton of electrical power to heat? If this was an AC device it would be easier. A switching power supply might be possible, but it would be huge. Anything else I can think of would just throw too much heat and be too much of a drain.

It's a brushless motor, the controllers are extremely efficient even at part throttle.

neutron256:
I'm all about commercial off the shelf hardware. So having something like the Maestro which is already configured to accept 0-5v inputs and control servos is very appealing. The question is whether it's code is strong enough for closed-loop boost control.
For my particular set-up I'm likely to be using MS3 in a parallel install for STR rules (MX-5, I'm just here for the e-charge). So I might be able to use it's native boost control to drive the Maestro as a 0-5v output.

-Grant

[neutron256]

If you're going to be using an MS3 I would think it would work pretty much the same way I'll be using the Unichip. Create a boost map and use the output to control the ESC rather than wastegate/blowoff valve.

The more I learn the more I think using a system that uses a map to control the supercharger is going to be much more effective than just full throttle activation, or some form of closed loop control.

With the Phantom setup they are saying part of the reason for only full throttle activation is because it's easier to tune. This makes sense because it limits the variables you need to deal with. If compressor speed is integrated as a sub map in the tune then it stops being a variable making the tuning process simpler.

If I have time this weekend I’m going to be connecting the stock MAP sensor to the Unichip and do some data logging. This way I can have a model of what the stock intake restriction is when I create my boost map.

[Grantmac]

I actually think the control could be as simple as pressure differential before and after the throttle plate. Past a certain MAP the SC would be ordered to produce X amount of boost above MAP up to a maximum value.
Or even just a question of at X MAP the SC should be producing X boost in the intake tract.

Or maybe we are just overthinking this and what it needs is a recirculating BOV with the SC set to engage at a lower TPS position?

-Grant

[neutron256]

Originally Posted by Grantmac

I actually think the control could be as simple as pressure differential before and after the throttle plate. Past a certain MAP the SC would be ordered to produce X amount of boost above MAP up to a maximum value.
Or even just a question of at X MAP the SC should be producing X boost in the intake tract.

Or maybe we are just overthinking this and what it needs is a recirculating BOV with the SC set to engage at a lower TPS position?

-Grant

Was there any doubt that we're all overthinking this? That's half the fun of it.

I like the idea of some sort of closed loop control but it could get tricky. Depending on how fast your motor/speed controller responds to changes a closed loop could result in surges/oscillation which wouldn't be good.

For now since my car is already set up with unichip I'm going with the open loop map concept. Since this will tie the boost map to my fuel and timing maps I think this will make tuning easier too.

I'll be interested to see how this works for others, and might even want to try a closed loop setup myself. I think the unichip would also support closed loop if I set it up correctly.

[Grantmac]

I think it would depend on if the ecu was able to equate ESC % to PSI and honestly I'm not sure how that would work.

Something as simple as the BOV for reducing boost with the throttle closed and a MBC acting as a controlled boost "leak" to reduce boost in the lower RPM.

I'm always looking for a mechanical solution to a problem.

-Grant

[NYCsubaruBRZ]

Originally Posted by neutron256

Well lets face it there are a lot of people on this forum who are basically kids and need that sort of reminding from time to time.

True we're not dealing with fuel here, but we are dealing with electricity which can just as easily start a car fire if not handled correctly.

if someone is stupid enough to burn down there new car with fuel lines or an electric supercharger they deserve to be inside the car.

[neutron256]

Originally Posted by NYCsubaruBRZ

if someone is stupid enough to burn down there new car with fuel lines or an electric supercharger they deserve to be inside the car.

Come on now, lets not have that kind of talk on this thread.

Some times it's not stupid, it's just a lack of experience. I mostly just want people to know this isn't a DIY, if you're going to attempt building your own electric supercharger, or even just install Phantom's kit you need to understand what your doing, and the risks if something goes wrong.

Who among us hasn't overestimated our abilities/knowledge and gotten bit because of it at some point?

[nonicname]

Originally Posted by NYCsubaruBRZ

if someone is stupid enough to burn down there new car with fuel lines or an electric supercharger they deserve to be inside the car.

i really hope you are only 18 years old and have that stupid teenage mentality
to say crap like that. if not you have a lot of growing up to do.
keep that crap out of this thread.

[DJCarbine]

Originally Posted by NYCsubaruBRZ

if someone is stupid enough to burn down there new car with fuel lines or an electric supercharger they deserve to be inside the car.

Its not hard to burn down a car. They are gasoline cans with electricity running everywhere and combustion in the front bit. It only takes a wrong sized fuse, a leaking fuel line, or failing wiring to cause a car fire.

If you accidentally rear-end someone, would you say that you deserve to die?

[neutron256]

Thanks everyone, now back on topic...

I continue to learn more about Unichip and it seems perfect for this application. I can create a boost control map based on RPM and Load (Throttle position in this case) and use it to directly output a duty cycle signal. This will allow control of the speed controller directly off the Unichip.
@Grantmac, I suspect an MS3 would also be able to perform this sort of direct control, but I couldn't say for sure.

This will allow me to eliminate the need for an additional Microcontroler making the whole system that much simpler. I probably still will be using some form of Microcontroler but it will just be used for monitoring the battery charge, and switching maps on the Unichip. This will turn the supercharger on/off based on either a manual switch, or turning it off automatically when the battery charge drops below a set level.

Thoughts?

[bakerr6]

Originally Posted by neutron256

Thanks everyone, now back on topic...

I continue to learn more about Unichip and it seems perfect for this application. I can create a boost control map based on RPM and Load (Throttle position in this case) and use it to directly output a duty cycle signal. This will allow control of the speed controller directly off the Unichip.
@Grantmac, I suspect an MS3 would also be able to perform this sort of direct control, but I couldn't say for sure.

This will allow me to eliminate the need for an additional Microcontroler making the whole system that much simpler. I probably still will be using some form of Microcontroler but it will just be used for monitoring the battery charge, and switching maps on the Unichip. This will turn the supercharger on/off based on either a manual switch, or turning it off automatically when the battery charge drops below a set level.

Thoughts?

yes and no. It can control a boost output, but it actually would be reading it from a MAP sensor in order to control and monitor the boost levels on a typical FI setup. I'm not sure how you would monitor the pressure on this one.

[neutron256]

Originally Posted by bakerr6

yes and no. It can control a boost output, but it actually would be reading it from a MAP sensor in order to control and monitor the boost levels on a typical FI setup. I'm not sure how you would monitor the pressure on this one.

I assume you're referring to the MS3 and I really don't know anything about its capabilities. The Unichip can do that sort of closed loop control based on MAP input. Since with this system we have direct control over the compressor speed independent of what the engine is doing I don't see the value in closed loop control if you can map it to Load/RPM.

Edit: But I would be interested in seeing how well it works if someone does it.

[rusty959]

I'm sorry guys. this thread was posted THE DAY I left for OCS with the Marines. But im on my way back now finally.

Before I left I had been watching fentons build with considerations in doing my own setup. Last year I built my own quadrotor using a beaglebone as the brain. Did all the programming from scratch in c++. Why is this relevant? I have several classes basically ready to go for things like motor control, sensor input, pwm reading and control, PID, and data read/write for things like config and logging. The beaglebone is very nice and flexible, but since the arduino runs on a similar platform I should be able to port the code to work for it as well. Same with raspberry pi, Although it may not have the I/o I'd want.

I am still a bit off from spending the money on a compressor and motor that would work, but im probably going to soon start playing around with what I have laying around and developing some code. Initial plans are a PID controller running off a table using throttle % and rpm to hit target boost. Once tuned this should eliminate probably all of the control issues that have been brought up. Might go ahead and write some stuff to control battery charging as well. Other suggestions for bells and whistles welcome.