# caveats of multiphase controller design



## NintendoKD (Apr 29, 2012)

I have to admit I am a bit curious. I have always thought that there was more than one way to skin a cat. but in terms of electronics, it seemed always, well..... a bit more concrete, but the more I think about it the more it is like anything else. Lets say, for example, you are building a high voltage vfd, you have 500~vdc bus to a frequency drive, that switches to three separate circuits, which runs them to a/c then directs them to the motor, or you have bus to vfd to single a/c to timer to motor, or you have redundancy, bus to separate timers, to separate verters to the motor, with a proc. between to synch. Or any number of other variations on this basis. While I agree that redundancy is nice, you are still hosed if one or more phases goes out "burnt igbt etc." efficiency loss does become somewhat of a concern, with more components complexity goes up as well, the simplest system seems the most logical, with the fewest components, and the lowest complexity, and fewer losses in terms of efficiency. thoughts? I would think that while pack voltages are not VERY safe above lets say 300vdc the inverse is also true, using a safe, low voltage is not VERY safe at lets say 1500ADC either this would easily melt the strongest of busses, even at low impedences. I am rather adamant of using high voltages at low amperages, but wonder about feeding power to such a beast. I like the old addage "inside every man there are two wolves, the dark, and the light. they fight in a perpetual battle, the one that wins is the one you feed. It may be interesting to note, that we would be using far vastly efficient wireless transmission of high frequency high voltage power if it were not that the dark wolf were fed. so to speak.

I ponder this, but am unfortunately not in a position in which I can perform any experimentation. I keep coming to a standstill. I go back to the math. I think "oh! this will work" then take out my trust calculator and soon realize that 3.05 tons of batteries wasn't what I pictured. Or, finding out that while 135hp is a nice little mover "the lotus elise exige has such an engine, the toyota 1zz fe" It takes roughly 100kw to operate a motor at that power level, and only for short bursts. I keep thinking "there has got to be a way" I hate being educated, at times, all I seem to be able to see are the ways not to do it.
I figure, 50 hp is more than anyone needs at the torque levels produced by said motor, 480v seems to be the ticket, as higher efficiency, and lower amperages necessary, batteries at this level are still escaping me, perhaps quinetic has the answers there. and then there is the tidy matter of designing and building, and testing the multiphase, vfd, regen controller to worry about. It really keeps me up at night, but I think it's the only thing keeping me going sometimes.


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## PStechPaul (May 1, 2012)

I have worked with high voltages as well as high currents, as well as situations where both are present and there is very high power and energy available. Mostly I have worked with AC, which has its own unique risk because at 50/60 Hz it can cause ventricular fibrillation, which can be deadly even when body current is as low as 20-50 mA. DC has its own dangers, mostly being the fact that it causes strong muscular contractions that tend to cause the shock victim to latch on to a conductor, and it can also cause welding and severe arcing especially when inductive loads are involved.

There are some combinations of voltage and available current that are considered "intrinsically safe". This depends on many factors, and can be as low as 6 volts (for some underwater devices) to 50 volts (such as telephone circuits). But it also depends on the available current, and thus also the amount of power and energy involved. And much of the literature has to do with safety in explosive atmospheres. Here is some interesting information:
http://www.compliance-club.com/archive/old_archive/000622.html
http://www.msha.gov/techsupp/acc/application/acri2011.pdf
http://www.mtl-inst.com/images/uploads/datasheets/App_Notes/AN9003.pdf
http://www.extronics.com/media/216502/329028_02_intrinsically_safe_circuits_at_radio_frequencies.pdf

There is a classification of electrical power known as "Low Voltage" which is actually 600V or less, and it encompasses a wide range of electrical equipment, wiring, and protective devices. The next classification goes up to 5000V and is known as "Medium Voltage", which is often used in high power industrial applications where motors may be rated at 4160V or 2400V which are common delta and star voltages.

For most EVs, 100 HP or 75 kW is about the maximum needed. Using widely available low voltage components, 240, 480, and 600 VAC and their peak DC bus voltages of 360, 720, and 900 VDC correspond to currents of 208, 104, and 83 amps, respectively, which can be handled by fairly common wiring as small as #6 AWG. The greatest danger in EVs is the DC battery pack, which holds an immense amount of energy. Being DC, it has the dangers of welding and arcing which are not as prevalent with AC. So for AC motors, the wiring out of the VFD is less dangerous than the DC bus link, but since the IGBTs connect to both sides of the DC bus, a major fault can cause the motor connections to be at dangerous DC potentials.

The modular battery pack with high voltage isolated DC-DC converters, as I proposed in another thread, provides a level of intrinsic safety by isolating the batteries to a relatively safe level of 12-48 VDC, and the high voltage output can only be produced when the electronic circuitry is operating properly and all interlocks are enabled. As long as the DC-DC transformer is designed to be intrinsically safe, as with split bobbin construction, catastrophic component failure will only cause limited damage and protection circuit activation in the isolated module. There are additional costs involved with this system, and it may not be able to supply the high overload currents often demanded by EVs, but that might be accomplished with external ultracapacitors or a string of small high-C-rate batteries that limit the total energy available to a safer amount.

For the DC-DC converters, a good idea of the cost can be estimated by the cost of an automotive inverter. I have seen them for as low as $50/kW, so a 75 kW system would cost $3750. The batteries for such a system (based on 3C) would be 25 kWh and probably $15,000. So this level of safety is only about a 25% adder.


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## ZEVDK (Nov 15, 2013)

Nintendo, there is only one cost wise relevant way to do a 3phase controller and it's pretty straight forward. Hexbridge arrangement of IGBTs, some input capacitors and the control of those IGBTs. It's essentially that simple although you have to know a collection of relevant aspect to do that right.

It can be quite inexpensive and what's particularly interesting is that you can use a rewound (for lower voltage) standard industrial AC induction motor for a car. Which go for as little as 150$ new from china.

And the controller can be done quite cheaply. Very, relative to how much of a holy grail it is. You can basically get a tesla drivetrain dirt cheap.

IGBTs can be extremely inexpensive. A good well suited TO247 part (like STGW50H60DF) can be 1$ in volume and you might need say 48 of those in a 100kW AC controller.
Panasonic 400V 47uF EEU-EE capacitors are also potent quality for money.
And that's roughly speaking the power side of things.


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## Tesseract (Sep 27, 2008)

ZEVDK said:


> ...
> And the controller can be done quite cheaply. Very, relative to how much of a holy grail it is. You can basically get a tesla drivetrain dirt cheap....


Oh lawd... if I had a dollar for every time someone posted how simple and easy power electronics is... there's at least two other posts this week saying the same thing. 

This your website, btw? http://www.zev.dk/df.htm


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## ZEVDK (Nov 15, 2013)

I didn't say it was easy, did I. I said you had to know several aspects to do it right and rather few know those. Although I have seen some succeed somewhat without knowing any of it, like Paul Holmes. He actually did a 3 phase controller with surprisingly poor insight. It was even used for a prototype for a serious commercial vehicle.
But I did say it could be done cheaply and it most certainly can.
You are however known for being discouraging and averse to cost optimization. Although otherwise you seem to be a good EE.

Try to hesitate your impatient criticism of me, then I wont have to point out your errors.


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## major (Apr 4, 2008)

ZEVDK said:


> Try to hesitate your impatient criticism of me, then I wont have to point out your errors.


Have you ever been a member of this forum under a different user name?


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## ZEVDK (Nov 15, 2013)

Pettiness moves quickly it seems.


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## major (Apr 4, 2008)

ZEVDK said:


> Pettiness moves quickly it seems.


So that would indicate that you are Dan Frederiksen; who was banned from this forum a while ago. Is that correct?


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## ZEVDK (Nov 15, 2013)

Obviously. Does that soothe your pettiness? to mindlessly derail the topic. To seek to hamper the best influence this forum has ever had.
And to brownnose Tesseract. Do your worst, petty man. Seal your fate.


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## major (Apr 4, 2008)

ZEVDK said:


> major said:
> 
> 
> > So that would indicate that you are Dan Frederiksen; who was banned from this forum a while ago. Is that correct?
> ...


I have reported this to the administrator. Hopefully he will remedy this unfortunate situation.


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## ZEVDK (Nov 15, 2013)

No he wont. He will be as petty and dark and mindless as you.

Tesseract, I fully expect you to be on the side of evil but this is an opportunity for you to voice your opinion on whether I should be banned or not. Which is all but a certainty at this point.


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## Tesseract (Sep 27, 2008)

ZEVDK said:


> ...
> Tesseract, I fully expect you to be on the side of evil....


I am evil, yes.


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## ZEVDK (Nov 15, 2013)

That generally doesn't end well Tesseract. But that's the problem with evil, it's absence of wisdom to hear the reason of the truth.

Before I go, are you working on an AC controller? or does Evnetics believe that overpriced mismatched DC systems are future proof.
I would feel terrible putting you guys out of business  Such a stand up guy


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## DanFrederiksen (Nov 16, 2013)

Good thing you were here to protect us from that guy, Major Asshole. Talk about IGBTs and those panasonic capacitors. Can't have that. Just the visionary optimism alone was ban worthy. What would the world be without your kind...
But I forgive you for you know not what you do.

So how about it Tessa, working on that AC? can't make it work? or just oblivious to the imminent death of DC.
Jack Rickard lost patience with DC about a year ago and as soon as there are high power AC controllers for even remotely reasonable money then that's all he will be promoting. Right or wrong he influences a big part of the market.

But why listen to me, I'm just a troll. What do I know.

I'm sure 2000$ brushed motors will maintain their appeal when 300$ AC induction motors are available. It'll be here forever just like lead acid batteries.


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## Hollie Maea (Dec 9, 2009)

Come on, guys, no need to bicker. Make market and sell your controllers and call it good.


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## Tesseract (Sep 27, 2008)

DanFrederiksen said:


> ...
> So how about it Tessa, working on that AC? can't make it work? or just oblivious to the imminent death of DC.
> Jack Rickard lost patience with DC about a year ago and as soon as there are high power AC controllers for even remotely reasonable money then that's all he will be promoting. Right or wrong he influences a big part of the market...


Oh, Dan... you're so anti-social you make me look like a career politician! Normally I either ignore or egg on trolls like you, depending on my mood, but the AC controller question is one that I have been getting lots of emails about lately so I'll address it seriously.

You more or less assume that our not offering an AC controller can only mean we are either incapable of making one, or are oblivious to market sentiment. It does not seem to occur to you - or anyone else, frankly - that a 3rd possibility exists: namely, that there is not a big enough market for an AC controller to justify its development.

I've said many times here that my propensity to develop new products for the DIY market is directly proportional to sales of our existing products. The fact of the matter is that we rarely sell more than 10 controllers per month to DIYers and that is just barely enough to pay the fixed expenses of operation. Evnetics is a business committed to reducing the use of fossil fuels through the electrification of transportation, yes, but take care not to forget the "business" part. I know a lot of you are closet Commies who think making a profit is evil, but the unfortunate fact is that none of my creditors will accept the love and adoration of the DIY community in lieu of actual currency to pay my bills.

You are correct that Jack Rickard is hugely influential in this market. In fact, we saw just how influential when around this time last year he started heavily promoting Curtis and Azure-Dynamics (despite the latter being bankrupt) and our sales promptly declined by approximately 40% over the next few months. That had an immensely chilling effect on us, as any market that can be so heavily swayed by one individual is, in effect, held hostage to said individual.

Fortunately, a way out of this dilemma appeared around this same time when we were seriously approached about developing a traction drive system for locomotives.

And so that is what we have been working on since February. In fact, it was just last week that we delivered the first prototype drive system - consisting of (2) 480VAC/3ph/1000A rectifiers and (4) 650VDC/1600A DC drives - to the customer.

Incidentally, almost all of the electronics for the locomotive drive system can be used in either an ACIM/PMAC or an SRM drive (only the IGBT drivers need to be modified). The locomotive hardware has an ethernet-based programming/setting/logging interface (similar to the Soliton controllers), but also a CAN-based control and logging interface. In other words, we more or less designed a complete "GEVCU" - along with the rest of the drive system! - in less time than Jack has been trying to herd his bunch of cats to do the same.

If it sounds like we have abandoned the DIY market - and Jack implied such in several of his EVTV episodes and blog posts - that couldn't be further from the truth. In fact, the success of the locomotive drive system will not only allow us to continue serving the DIY market, and maybe even offer more products for it which would not be economically justified otherwise.

We put an immense amount of thought into deciding what to do, and even more into actually doing it. If you think can you do a better job than us all I have to say to that is,

Come at me, bro...


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## DanFrederiksen (Nov 16, 2013)

Tessa, calling me a troll should be beneath your intelligence. Provocative yes but only as a last measure to induce some bare minimum mental mobility is my lesser fellow men. By default I am quite kind and considerate. You may notice that you started the attitude in this thread.
I am banned by idiots so objecting to such does not constitute trolling or asocial behavior. That's a righteous grievance. 
I could have accepted ban in silence but then how would a super idiot like Major ever have the chance to learn and be a better man. Indeed how would you learn from it.

And no it didn't occur to me that there is no market for AC because that's just not true. And I'm fully sympathetic to capitalist reality. I missed neither.
And if you were to depart DIY for bigger markets I couldn't fault you for that but as long as you are in DIY then you are a fool for not seeing the coming significance of AC. And I say coming only as a result of fools not starting it sooner. People don't buy DC because it's better... they buy it because there are no AC systems of even remotely reasonable price. And despite its popularity the 5000$ Curtis set is still highway robbery. Very far from the very substantial potential of AC drive.
Drag racers might still hold on to DC for a while but everyone else will go AC if available. You couldn't sell a DC system if there are AC systems of same price or lower. And you should understand the significance of that truth. Or it will teach you the hard way.
You can pretend I'm a troll all you want but that fact is coming for you.
Or it would be more accurate to say that it has already come for you but somehow the 40% decline in sales and the repeated emails calling for AC drive failed to register in your mind. I can see how that would be too subtle..
Maybe this provocative post will be your wake up call.

You're a pretty good EE but there is seemingly one key blindspot (other than AC) and that's cost optimization. Or maximization of the value proposition for the customer. You see that ingot design you use with the solitons, I'm guessing it's not the cheapest case design ever.. Now granted the block of alu fools a lot of customers into buying it because they confuse mechanical robustness with worth much like audiophools do. Jack is heavily influenced by bling as well so that actually works in your favor to some extent but if competitors can do an equivalent product for much less without it then you are quickly at a serious disadvantage.
So if/when you do an AC, keep price in mind. I don't know what IGBTs you use and like Otmar, you're probably not going to share that but if it's substantially less cost effective than for instance the IGBT I mentioned above then it's something to reconsider. Along with every other cost item. This makes the engineering process a lot slower perhaps but once done, it's significant enough to change the world.
Don't look at your current AC sales because naturally you have none. Don't look at dwindling DC sales because the stupidity of that should be very evident. Have the vision to realize the AC makes a market. Especially when you consider the low cost of power electronics and that good car size industrial AC induction motors go for less than 150$ from china including being rewound for EV use. And that's not a typo. One hundred and fifty dollars.
And please don't make the simpleton mistake of assuming I don't know what I'm talking about.


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## major (Apr 4, 2008)

DanFrederiksen said:


> ...Major Asshole.....





DanFrederiksen said:


> ... a super idiot like Major ....


You notice I have never called you names? For the most part I ignore you. That has worked well over the years. I do occasionally acknowledge your existence in cases like this when I request your banishment. Hopefully you will be gone again soon. Please do not return.


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## DanFrederiksen (Nov 16, 2013)

Calling for my ban is what makes you a super idiot.
You don't have to call me a name to be worthy of a name. But logic is not your strong suit.

You see I'm a really intelligent person who is very dedicated to the cause of electric cars and I say some really intelligent things that are very constructive and help the EV community more than anyone else by far.
The things I say are insightful and pertinent to the point of changing the world if only you densoids would listen.
So when you call for a ban of the best person here, that makes you a super idiot. Petty, dark, mindless. Scum of the earth. So little remorse, such mindless faith in your petty impulses.
How can I read you this well? because I'm a genius and I have dealt with oceans of your kind before.
As Einstein said, there are only two things infinite, the universe and human stupidity and he wasn't sure about the former. He spoke from bitter experience. And like me he was an extreme left wing pacifist genius.

And no, your response to this wont be a surprise either. Absolute stupidity is nothing if not predictable. Although I am continually puzzled by how it is possible to be so void of reason.

I don't even remember why I was banned originally and likely neither do you but it was something like insisting that DC had no future or that we needed to develop cheaper components and that it's quite possible. A cardinal sin to be sure.
Not that you have the mind to realize it but that's no reason to be banned.
Yet the desire to ban me is seething. And pointing out the error of that desire only cements it.

What a piece of work is man.


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## Brute Force (Aug 28, 2010)

> Especially when you consider the low cost of power electronics and that good car size industrial AC induction motors go for less than 150$ from china including being rewound for EV use. And that's not a typo. One hundred and fifty dollars.


Please provide links and source information for the brand new, low cost, road worthy drive train components of which you speak.


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## major (Apr 4, 2008)

DanFrederiksen said:


> Calling for my ban is what makes you a super idiot.
> You don't have to call me a name to be worthy of a name. But logic is not your strong suit.
> 
> You see I'm a really intelligent person who is very dedicated to the cause of electric cars and I say some really intelligent things that are very constructive and help the EV community more than anyone else by far.
> ...


The genius who compares himself to Einstein and Jesus can't even remember this: 


david85 said:


> Enjoy you're vacation, Dan.


And he wasn't insisting DC had no future at that time. He was exhibiting bad behavior after being called to task for giving erroneous advice on the application of a DC motor.


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## onegreenev (May 18, 2012)

Brute Force said:


> Please provide links and source information for the brand new, low cost, road worthy drive train components of which you speak.


Dan can't provide links. Never could. For the past 4 years or longer he has touted his superiority but yet remains in his little digs in his home country. Never moving forward. Never growing never building but does a lot of talking. Talks the talk but can't walk the walk. He is still waiting for that elusive money bag person to fund his ideas. Never once considering he just might have to fund it himself. God forbid he has to spend his pittance on a project.


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## CKidder (Dec 12, 2009)

Tesseract said:


> And so that is what we have been working on since February. In fact, it was just last week that we delivered the first prototype drive system - consisting of (2) 480VAC/3ph/1000A rectifiers and (4) 650VDC/1600A DC drives - to the customer.
> 
> Incidentally, almost all of the electronics for the locomotive drive system can be used in either an ACIM/PMAC or an SRM drive (only the IGBT drivers need to be modified). The locomotive hardware has an ethernet-based programming/setting/logging interface (similar to the Soliton controllers), but also a CAN-based control and logging interface. In other words, we more or less designed a complete "GEVCU" - along with the rest of the drive system! - in less time than Jack has been trying to herd his bunch of cats to do the same.


Full disclosure: I was his favorite cat for a while (that is, I was the one who started coding up the GEVCU project. We're still doing it but not with him any longer.) Now that that is out of the way: I would certainly hope that you could beat us in terms of speed. After all, you're essentially comparing people who are doing this nights and weekends as they have time against someone doing it commercially. Believe me, if I had real commercial backing or some commercial incentive to do the GEVCU work it'd go a lot faster. But, it's open source so that sort of limits the commercial incentive. And, yeah, that project has gone pretty slowly. It's coming along though and I think things are gaining steam in the background. I think that the idea is still valid, useful, and its time has come. Controller companies shouldn't have to built support for every BMS out there and BMS companies shouldn't need to directly support every charger that someone might use. It seems like a common ECU that sits in between is an idea long overdue.

I am glad that you got that locomotive project and I hope it goes well and potentially allows you to enter the DIY EV space with an AC controller in the future. I'm sorry that Jack's influence had a negative effect on your business. One might even say that my work sort of contributed to that but of course such a thing is not and was not my intention at all. I just happened to have the DMOC and Siemens hardware and needed something to drive it all. I've historically been a bit of an AC drive snob but I'm starting to see that that is silly. Having said that, I've always thought that your Soliton hardware was very nice and if I were to build a DC system your Soliton system would be in the top 2 controllers I'd consider using.




> If it sounds like we have abandoned the DIY market - and Jack implied such in several of his EVTV episodes and blog posts - that couldn't be further from the truth. In fact, the success of the locomotive drive system will not only allow us to continue serving the DIY market, and maybe even offer more products for it which would not be economically justified otherwise.


Jack implies a lot of things about a lot of people in his episodes and blog posts. I certainly have gotten the brunt of this as well. It's a shame that he has such a large and visible bully pulpit. I am of mixed opinion as to whether his existence in the EV world is a net positive or not. It probably is a net positive thing but there's plenty of negatives in there as well.

As I said, I do hope that your other work can lead to additional DIY products. My goal with the GEVCU project is to support every piece of hardware a DIY person could conceivably get their hands on. So, the more the merrier. It started out as a project to allow those of us with DMOCs to use them but my goal is much more than that. That was just the beginning. I'd certainly be interested in supporting anything you come out with.


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## Tesseract (Sep 27, 2008)

CKidder said:


> Full disclosure: I was his favorite cat for a while...


Yep, this I knew, though I imagine that was somewhat of an awkward arrangement, given your previous (continued?) association with NetGain Controls...



CKidder said:


> I would certainly hope that you could beat us in terms of speed. After all, you're essentially comparing people who are doing this nights and weekends as they have time against someone doing it commercially.


Sure, we had commercial incentive spurring us on, but we also had to design, build, and code an entire multiple-drive/rectifier system, and not just the CAN bus interface for a single drive. So, not exactly an apples to apples comparison, really. 

That said, I was basically making the same point as you did - that commercial incentive leads to a much snappier development pace. And commercial incentive with a crapload of debt piled onto it can result in a downright _blistering_ development pace... 



CKidder said:


> I think that the idea is still valid, useful, and its time has come.


The GEVCU idea is good in principle, but it looks more like the proverbial solution in search of a problem at this point in time. The original design intent for the GEVCU was to make something that could operate the AzD DMOC645 inverter, but that seemed like a lot of work for little reward as Jack only has something like 66 of these inverters to sell (and has only sold 21 over the past year... let that number sink in for a moment...). 

Hence it makes sense to expand the capability of the GEVCU to operate other CAN-bus enabled devices, but what else is there for it to operate either now or in the near future? Rinehart Motion Systems inverters? I guess, but even if they were to cut the price of their PM100DX in half it would still be a rather poor value proposition (ie - $4000 for a 100kW inverter). 

On a more abstract level, who will ensure the hardware and software are fail-safe and can't possibly get stuck sending full torque/speed commands to the inverter? Theoretically, open source stuff should be more robust because lots of people are poking at it, but the opposite seems to be the case: without a firm and consistent person in charge and a financial incentive to do things right (and not just a moral incentive) the quality of the design tends to suffer. Also, I don't care how much of a philanthropist you are, at some point you will get tired of toiling away on the GEVCU for nothing... probably right around the time you feel it is working well enough for your DMOC inverter.



CKidder said:


> I'm sorry that Jack's influence had a negative effect on your business. One might even say that my work sort of contributed to that but of course such a thing is not and was not my intention at all.


No need to apologize. Competitor != Enemy. Heck, I even exchange a friendly email with Otmar now and then... 

As for Jack's negative influence on our sales, the conclusion we came to is not so much that he is a dominating force (though he is certainly influential) but rather that the DIY controller market really is terribly small. 

And of course this is nearly a zero-sum game, in that when a person chooses a Zilla or an AzD or a Curtis/HPEVS controller for their EV it is extremely unlikely they will also buy an Evnetics controller as well.


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## JRP3 (Mar 7, 2008)

Damn, how did I miss another DF meltdown thread? Always entertaining, I think he's been kicked off more EV sites than even Jack himself 

Tess, glad to hear you're getting some honest work beyond our cheap ass DIY crowd  Jack loves to pretend there are tens of thousands of us building EV's and we are going to change the world, ignoring the reality that the OEM's have already far surpassed our numbers.


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## Tesseract (Sep 27, 2008)

Well, the (potential) locomotive customer won't finish installing the prototype drive system until sometime in February, so we ain't making an honest living outside of DIY sales just yet...


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