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[EVDude]

Well Hi Gang.  Its "Don the Electic Car Guy" here.  I did the New Beetle EV Project a few years back with a high voltage Siemens system ( see http://www.cameronsoftware.com/ev/Welcome.html for all the gory details).

I am wanting to do a lightweight dirt bike (around 100kg total weight) and am investigating various drive systems.  I cannot seem to find any high voltage AC systems - are there any readily available for smaller applications (7-8kW nominal)? 


thanks
Don

[frodus]

Why do you want to use high voltage if it's only 7-8kw? You don't NEED to go high voltage and there's not really much benefit at those power levels. Using FET's keeps things way cheaper. Going high voltage in a motorcycle isn't really needed IMHO, keep it at 96V or so, there's plenty of kits out there that are perfectly matched (or specifically designed) for a motorcycle.

Consider a Motenergy Dual stack PMAC motor and either a Kelly controller, or a Sevcon (make sure it's pre-programmed). If you want AC Induction, then the HPEVS AC9/12/15/20 combo's are a great setup. I have an AC20 and love it (and I also sell them).

[EVDude]

I can understand your bias for the lower voltage motors (you sellling them).  Please, I do not want to get into a debate about why.

I would like to go 300V (ish) and wondering if there are any offererings of these smaller motors and controllers with higher voltage.  

thanks.

[frodus]

I don't have bias and it’s not at all because I’m a reseller…… I shared my experience with you because I've actually done the work you're doing right now. I told you exactly why it's not economic to use high voltage on a motorcycle with a small pack and low power. I bought my motor after looking at all the solutions out there and just ended up selling them to help guys like you, not to make money. I've got a full time job and It's more about helping people. Notice that I mentioned 2 other solutions before I mentioned the ones I sell..... thanks for assuming..... but I was just being nice.

The issue with higher voltage in these applications (yes, I’m actually an applications engineer and have been doing EV tech support, vehicle design, component selection and schematics for about 4 years now), is there's a point where it works out better cost wise, and unfortunately with these power levels high voltage costs more than it's lower voltage counterpart. With your car, it works out because the power levels are sufficient enough and FET’s just won’t cut it, and losses are too high. With high voltage, as you know, you need your components to be rated for higher voltage, you can no longer use FET's and things start to get more expensive, and the available controllers decreases exponentially (which I'm sure you've also found out). If you want high voltage, there's not a ton out there, and even though they are high voltage, they're also high power and much larger and heavy. Sevcon, Rinehart, Brusa, Azure Dynamics, all make inverters in the voltage levels you're looking for, but they're complete overkill and way more expensive than a lower voltage counterpart that matches your power requirements. Other than that, a low power, high voltage inverter for a motorcycle is going to be hard to come by unless you design it yourself, or pay someone to design you one. I've shared my solutions with you because you asked. Aside from you wanting "to go 300V (ish)", there's no reason that these solutions wouldn't meet (and exceed) your needs.

I'm an engineer and teacher first, sales comes last.

[EVDude]

OK thanks for the info.  As I said, please, I dont want to debate this.

I am in the market for higher voltage AC motor/controllers  if you know of any that are available, I would appreciate the information.

thanks.

[frodus]

I would like to go 300V (ish) and wondering if there are any offererings of these smaller motors and controllers with higher voltage.

I'm not debating. There aren't any low power high voltage controllers right now in the EV market. There are however high voltage, high power controllers, of which I gave you the names. You could use an industrial VFD that has the ability to connect to the DC-LINK (basically after the rectification of the mains voltage)... and hook up a pack to that, but it'll require some experience in VFD programming and setup. There's plenty of 120/208V motors out there so you should be fine finding at least a motor, but be prepared for lots and lots of tuning and dialing in the motor to whatever inverter/VFD you choose.

Let us all know how the search goes, dude.

[Bogan]

I'm with frodus on this, highest voltage motors I've seen for bikes are around 100V, and (from memory) even those are going to be heavier than your plan allows.

If you want the best build, think power/weight, and leave the arbitrary constraints behind. A 100kg dirtbike is an ambitious build without making it more difficult for yourself.

[EVDude]

I am sounding like a broken record.  - I do not want to get into a debate about it. - All I wanted to know if there was anything available. Simple question.  Sounds like for the hobby market - no.    Keerist.

[Bogan]

Perhaps there is a lesson to be learnt there, if the record is broken, maybe its time to change the tune. I've seen far too many projects not realise their potential because of poor design (component selection), which should have been obvious in the design stages. Remember, we're just trying to help; although now I'm also curious as to what benefits a high voltage system can offer over the more common voltage ones, cos I cannot think of any.

[CliC]

From what I'm reading, the advantage of higher voltage is a little more drivetrain flexibility, at least in theory. With higher voltage, you can have higher motor RPM, which means you can gear for better low-end torque with less sacrifice in top speed.

I'm not sure how much you really need, though. The highest stated figure I've seen on a race bike is around 150V. And I'm sure there are numerous other constraints in using higher voltage as well.

[frodus]

EVdude,
Already said that there isn't much (if anything) in the low power level with high voltage:

a low power, high voltage inverter for a motorcycle is going to be hard to come by unless you design it yourself, or pay someone to design you one

I also told you that there are AC controllers on the market, although they're high power. Get a Rinehart, Siemens or Brusa and be done with it.


Best of luck.