Theres a thread somewhere on here that discusses the below issues at length - ill post myself if I can find it, unless someone else does first?
ElectricGod wrote: ↑Oct 17 2019 12:43amNot true...depends on what you are doing and why.sn0wchyld wrote: ↑Oct 16 2019 9:31pmhigher voltage controllers (mosfet based) are really only of benefit if you have a slow wind motor that is significantly underutilized at 80VDC, that you cant rewind (for whatever reason)... at least until you get to really big power levels where conductor sizes and breakers can get impractically huge (we're no where near such sizes here). I have one such motor that I haven't yet got round to rewinding (too many projects!) from its 17kv now to ~50kv - a higher voltage controller would be good and save me time/effort, but still not as good as a rewind for higher kv (80VDC mosfets are the highest power density, for example). Runnning 500A conductors really isn't so bad compared to dealing with 300VDC . One is just a bit more copper, the other is properly deadly. One is transient, the other is perpetually hazardous.
1. The hubmonster, when they were being manufactured were put on scooters and ran at 60v. Despite that, this motor does much better at 130v than it does at 60v and might be even better yet at 200v.
2. "Slow wind" indicates low Kv or lots of turns per stator tooth. This means more resistance in the windings compared to motors with a higher Kv.
3. All motors at higher voltage have a broader power band than they do at lower voltages. This is quite advantageous to have. There's excellent reasons why electric car makers use 380v.
4. Some motors due to the iron losses do poorly at higher voltages. I have a couple of large inrunners. They heat up running above 82v. These motors are a bad option above 82v. Others do great at higher voltage.,
5. Any motor is capable of only so much wattage. Current is what heats up a motor, not voltage. So to maximize motor wattage, run it at higher voltage and less phase current so it heats up less.
6. I've done rewinds on outrunners. I always get more copper on them than they had from the factory.
7. I think you need to read up about electricity. Current kills, not voltage. How many times have you been shocked by static electricity? That's voltages in the 100,000 to millions of volts range, but may be 10mA of current. Compere that to 48v and 400 amps...which will cook you to a crisp in seconds
So yeah...150v Nucular controllers would be way cool! I'd be running them at 131v just as soon as I could build the battery pack!
1. The hubmonster, when ...
This is why i mentioned rewinding motors - did you read my post at all? Yes, wound for 150+V they need... 150+V to realize their full potential. Rewind them for 80V will achieve the same as running them at 150V, only your controller will be better, and voltages (marginally) safer.The motor im talking about above is a mini monster after all...
2. "Slow wind" ...
ture, but irelevant when it comes to torque production. If you halve the Kv, you halve the turn count - so you can double the parallel wires, ie halve the reistance. Then you've only gone half as far for each winding, so you end up with 1/4 the reisistance... so the same copper losses per unit of torque produced. I^2R=P after all.
3. All motors at ...
No, read above. if you change the winding, then you end up at the same place. Cars use higher voltages because they have the funds to pay for safety systems, and at the same time 6+kA is hard to manage vs such safety systems. We're not talking about 500kw systems though - not even 1/10th of that. Im guessing you also skipped over where I said 'MOSFET BASED'? IGBTs are a different story/beast, as are the power levels involved.
4. Some motors due to the iron losses do poorly at higher voltages.....
Again, its not about voltage, but about the rpm they hit for a given voltage AND winding. Rewind those large in-runners with double the turns per tooth and they'll do fine at 82+v (assuming the motors do fine at 41V). Their torque capability wont shift at all though.
5. Any motor is capable of only so much wattage...
You just gave an example where maximizing voltage caused issues... see your own point #4. You can get a motor and match it to a controller with the right voltage. or you can get a controller with the right voltage and match it to a motor. The highest power density controllers are ~80VDC, so its (often, not always) worth getting or rewinding a motor to suit such a voltage, at least until >50-100kw. The relative simplicity of lower voltage is just a added bonus. There's a reason you can easily get a 12vdc switch to break 1000A (12kw) but relatively hard to find a 120Vdc swith to break 100A (still 12kw) and even harder to get a 1200Vdc switch to break 10A (still... 12kw). DC is a bitch to break as voltages rise, it maintains an arc easily and for a long time, particularly when coming from low impedance sources like batteries.
6. I've done rewinds on outrun.....
Not sure your relevance here? more copper fill is almost always good. Not relevant to rewinding to suit different voltages
7. I think you need to read up about electricit....
How do you get current to flow through something, like say... a motor? is it... voltage?
The fact is you need BOTH to be dangerous, because one is dependent on the other - and the quantity needed is dependent on the situation. 400VDC batteries are incredibly dangerous, because 400VDC is enough to get the current flowing through your skin, once the skin barrier breaks down your a dead man, because we are basically sacks of impure (ie highly conductive) water, covered in a thin layer of rather poor insulation (skin). 80VDC is far safer (Though still potentially deadly, ie if your hands are sweaty or you have a cut thats bleeding) because with dry hands you'll probably be fine to touch the terminals, though if you lick them say good by to your tongue. V=IR after all...
Me thinks it is you who need reed up on electricity (particularly low source impedance DC), young grasshopper
So yeah...150v Nucular controllers would be way cool!.......
The hubmonster...a 6 phase hub motor does great at double its design voltage (60v). It does fine at more than that. I have a couple of outrunners that do great at better than 40+ over their spec'd voltage. Just depends on the motor.
Again, and hopefully for the last time... only if you cant/dont want to rewind a motor. 150V controllers wont have the same power density as the current batch of ~80V controllers either, they'll be larger per kw (all else being equal). Rewind your motor with ~60-70% of the turns it currently has and run it at 80V with the current batch of controllers, and you'll be in a better place than waiting on a 150V controller - both because you'll have a higher power density controller, an easier/safer voltage to deal with, and you'll be able to get it by next week if you really want/have some time, just buy some wire and your good to go... vs ???? months/years until a 150V controller is developed (if ever).
Not that anybody will ever acknowledge this, but for a while in the 1990's I worked for a company that rebuilt and serviced industrial breakers. The smallest breaker I serviced was rated for 3 phase AC at 120v per phase and 600 amps.
Cool story. I've had electricians working for me that, despite decades of experience in AC and DC systems couldn't hook up 4 lead batteries in 2S2P configuration, calling me in confusion as to why they were getting 0V rather than 24V... despite having instructions, schematics and photographs of built units in hand. Experience is only useful if its relevant and you learn from it... and im unsure what experience with AC mains breakers in particular has with DC batteries, controllers and motors and how they interact WRT the motor windings. They are very different beasts other than the movement of electrons.
Happy to answer if you have further questions, but otherwise ill go the way of sam, and only answer this 'argument' for the sake of other readers. Vasilli, love ya work mate. Hopefully this saves you some work given you're already struggling to keep up with demand!!!