Open Inverter with Hyper 9

[mikejh]

Yes it's a lot of money. But I don't doubt the amount of time and manufacturing cost that goes into it. Especially for a small volume outfit and fully CNC machined. Can't expect China prices.

I like your idea of the MG2 internals in a new case. Those figures sound doable. I might have to watch some more of Damien's videos...It's been a while. Lost track of what he's up to.

Yeah the rear battery box was originally meant to hold 20 cells. I pushed it to 24 and now thinking of 26 to make a total of 100 cells.
I had panned to use the CALB 72ah cells so that gives me a 320V nominal pack at 23KWh.
I had looked at other cells/packs like the LG Chem's but a single series string gave less total KWh and packaging wasn't as flexible.
Quite like the idea of sticking to LiFePo4 cells as well... LG Chems remind me of Chevy Bolt.... don't charge them past 80%.... don't charge them indoors...

Having a bit of trouble estimating the CD and frontal area of this thing. I did a spreadsheet with some calc's and plugging in a (guessed) figure of 0.9 for CD and 1.35 frontal area shows about 17.2KW on flat ground with 98% efficiency @ 100km/h. This comes out at a range of 133Km.
Of course if I take the speed down to 60km/h it goes up to 326Km range. But who wants to cruise at 60... think I'd get a few middle fingers.
I think the frontal area might be worse than that though given the two fat tyres sticking out in the breeze. Fairing would help no doubt but not sure I want to go that way. Also not about to put pizza cutters on it just to gain a few K's of range... it's got to look good too.

[olegil]

What I figured is, it's rated for 1000 RPM at 48v, if I need it to rotate ~5000 RPM, I just give it more voltage, tell the controller higher frequency, and it'll go. There was moderate skepticism that it would handle 200-400v typical of an EV, but Major figured it would easily handle 10-12,000 RPM, so, that wasn't a problem.

I've only ever heard about voltage limitations for speed (too low and you won't get enough speed, too much back-emf), voltage limitations for arcing (mostly commutator issues, not an AC problem), current limitations (wires will melt), and RPM limitations (balance and/or core will eventually fly apart). This is the first time in 5 years that I've ever heard anyone mention anything about a frequency limitation of some kind, and I don't really grasp what or how that limitation is coming into play.

There are two limitations when it comes to driving an ACIM faster than the nameplate spec. One is the quality of the insulation material at multiple kHz frequencies of PWM. This is more a "is this suitable for use with an inverter at all or not" type of question. If it's from a forklift, it's obviously meant to be used with an inverter, so this should be fine. Not guaranteeing anything, but if it failed on this point I would be seriously surprised.

Then there's the frequency. To get a 50Hz 6-pole up to 5000 RPM requires somewhere between 250 and 300 Hz. That's a lot. But most inverters on the market go to 400Hz for a reason, so I don't REALLY see the problem with that either. It's almost like they're meant to not only overdrive a 2-pole, but are made to overdrive an 8-pole motor used as a 2-pole motor substitute.

If this is an air-cooled ACIM, you have a HUGE advantage, though. The fan will rotate at 5000RPM instead of 961, so you'll get MUCH more cooling. Typically a 15kW 50Hz will be specced at 18kW 60Hz, so at 270Hz (or whatever) you're likely not gonna worry about rotor temp.

[johu]

As for the fan I removed it in my Polo conversion. It adds a lot of drag, is super noisy and after all it isn't really necessary as the motor is cooled by headwind.