Open Source Electric Supercharger

[litemup]

Originally Posted by dtek

See post #629/#630 on page 29

Cool. Thx for the assist.

[litemup]

Originally Posted by neutron256

People have different goals. Most of us want a more sophisticated control system that at the very least uses throttle position. Other options are boost, RPM, or all three.

Got it. I've had my FR-S for about a month now and have also been kicking this around in my head a little. Just stumbled onto your thread.

I have some work to do in order to understand what kind of real-time data is available from this ECU. Rather than jump in and start blurting out a bunch of crap, I'll hang back, focus on my homework and follow along here with great interest.

[neutron256]

Okay so I'm working on designing a 12V compressor setup to test and see how it will work. If it works it would be simpler, lighter, and cheaper, but not as much boost.

Compressor

Garrett (or Garrett Clone) T3 Turbo compressor $130

Motor

TP Power 4040 3D Brushless Motor $97

• 4790kv
• Max Amps: 350
• Max Volts: 12V
• Continuous Power: 1650W
• Max Power: 4200W

ESC Speed Controller

Turnigy Fatboy V2 $273

• 300A Continuous
• 380A Surge

Control System

Unichip Piggyback Tuning Module $445 (can be found used much cheeper)

• Input from MAF, TPS, and Crank Position sensors
• The ability to create boost maps to precisely control the compressor motor
• Ability to switch maps on the fly
• Ability to tune fuel and timing for specific maps (when in boost)
• I may add a connection to the stock MAP sensor for closed loop control

Battery

Odyssey PC680 x 2 (one for starting one for powering the compressor) $208

• Pulse hot cranking amps: 520
• 16 Ah Nominal capacity

Charging System

WirthCo 20090 Battery Doctor 75 Amp/100 Amp Battery Isolator $59

• Charging directly from the alternator at up to 100 amp rate
• Priority charging for starting battery
• Manual override for starting battery
• Automatically charges auxiliary battery

Misc. Hardware and Materials

Approximately $200

Approximate build cost: $1412

Since I have most of these parts from my experimenting my cost is much lower, but I wanted to give an idea of how expensive this would be to build from scratch.

[neutron256]

For those interested Vishnu has released the beta for their Phantom ESC tune for OpenFlash Tablet.

http://www.ft86club.com/forums/showthread.php?t=69378

[litemup]

Originally Posted by neutron256

Control System

Unichip Piggyback Tuning Module $445 (can be found used much cheeper)

• Input from MAF, TPS, and Crank Position sensors

I wasn't able to find anything on the website that mentioned output channels or interface from the module. How will the above be measured/sampled?

[neutron256]

Originally Posted by litemup

I wasn't able to find anything on the website that mentioned output channels or interface from the module. How will the above be measured/sampled?

I purchased a tuner's license for Unichip specifically to use it for this project. There are two outputs that can be configured as a simple 0-5v duty cycle signal with a selectable frequency. An RC servo signal is needed to control the brushless motor speed controller. At 50hz that is 5-10% duty cycle.

[litemup]

Originally Posted by neutron256

I purchased a tuner's license for Unichip specifically to use it for this project. There are two outputs that can be configured as a simple 0-5v duty cycle signal with a selectable frequency. An RC servo signal is needed to control the brushless motor speed controller. At 50hz that is 5-10% duty cycle.

What are the increments at which the PWM outputs can be modulated?

In other words, into how many steps can a 1ms change be divided? If you already know what I'm getting at, please feel free to give me the "yeah, yeah, I've got that all worked out..."

[neutron256]

Originally Posted by litemup

What are the increments at which the PWM outputs can be modulated?

In other words, into how many steps can a 1ms change be divided? If you already know what I'm getting at, please feel free to give me the "yeah, yeah, I've got that all worked out..."

In filling out boost map table you can take it down to one decimal place if I recall correctly. So that would from 5-10% duty cycle that would give you 50 steps. It also transitions between points on the map so even between say 5% and 5.1% it won't just jump from one to the other. It will gradually modulate the signal as it transitions from one point on the map to another.

[litemup]

Originally Posted by neutron256

In filling out boost map table you can take it down to one decimal place if I recall correctly. So that would from 5-10% duty cycle that would give you 50 steps. It also transitions between points on the map so even between say 5% and 5.1% it won't just jump from one to the other. It will gradually modulate the signal as it transitions from one point on the map to another.

Hell, 50 steps between OFF and WFO is plenty.

Thanks for entertaining my questions. I'll get back to playing catch-up. Lots and lots of details to consider.

[litemup]

Per our PM, here's the spectrum analysis of audio from about 2 seconds into your last test.

Your assembly hit its first resonant mode at about 22 KRPM. That's where I am worried it will cause either premature bearing failure, probably in the motor, or might cause a fatigue fracture in the turbo housing

AT was asking about peak speed. It's about 31 KRPM

[Reaper]

so I really have no purpose in this thread but I used to be an RC car guy. Why is no one using a MAMBA Monster? At 22volt my 4wd 25 pound rc car will do standing backflips across a parkinglot.

[neutron256]

Originally Posted by litemup

Per our PM, here's the spectrum analysis of audio from about 2 seconds into your last test.

Your assembly hit its first resonant mode at about 22 KRPM. That's where I am worried it will cause either premature bearing failure, probably in the motor, or might cause a fatigue fracture in the turbo housing

AT was asking about peak speed. It's about 31 KRPM

Very useful. What software are you using to do the analysis?

I'm not surprised by the resonance. It's a massive impeller and it's almost impossible to balance it well enough for those speeds. As I learned already a 6mm motor shaft isn't enough to hold up to that slight imbalance, and even though an 8mm shaft can hold the wheel in position the vibration is still there. No doubt this will lead to failure of some component (most likely motor bearings) sooner they they otherwise would. There are billet impellers (rather then cast) which would be lighter and probably better balanced but the are also very expensive.

This is part of the reason I'm also working on a smaller compressor based on a T3/T4 turbo. I'm planing on testing both and seeing which is overall best.

[neutron256]

Originally Posted by Reaper

so I really have no purpose in this thread but I used to be an RC car guy. Why is no one using a MAMBA Monster? At 22volt my 4wd 25 pound rc car will do standing backflips across a parkinglot.

It looks like a hell of a motor, and on par with some of the other motors we've found. It's Castle Creations so I'm sure it's top quality, but with it comes with a high price tag.

A good suggestion at 22V is in the right range for a 24V system. It might be over driving the motor a little bit but not too seriously I think.

[Reaper]

im a little behind but I still have all my gear. A CC Mamba Monster running hard in a traxxas Erevo with a fully programmable ESC at 22v on 2X 3 cell lipos at 5500Mah each. It pulls so hard the centrifugal force will rip the tires off their little beadlocks, literally. In the RC world its(was) the holy grail of motors. There is no known driveshafts in the RC car world that will hold up to the Monster.