Hemonster wrote: Say however that you wanted to implement a rotary converter, does that mean turning the 3P AC motor with another 1P motor
No need for that, just use capacitor start. These are cheap and available, though you may need several in parallel.
and asking the inverter to effectively regen the energy back into the pack?
Yes, you do a flying start, which tells the controller it's not starting the motor from rest, so figure out what it's doing from back emf and/or the resolver, and yes, exactly that, demand negative torque and it will do the rest.
Oops, I've just realised it's not quite that simple. Usually it will implement negative torque by changing the slip, which means increasing the frequency a few Hertz, but it must not ever change the frequency. Somehow it has to be told that the frequency is not changeable. It should vary only the duty cycle. Again, this is sounding like a bit much to ask of an industrial controller.
So my brake chopper idea is starting to sound better. I'll whip up a circuit soon so you can appreciate the genius of it
Edit: It's in this thread
I would think that means you need to be able to disengage the motor from the drive shaft which means retaining the gearbox.
Yes, if the motor spins you need that.
Anyway, if you were able to disengage the motor, what speed would it need to spin at? I suppose whatever sync speed the driving motor is, the slippage (ie. charge current) of which is controlled by the inverter?
It will be spinning at a little under 3000 RPM (for 2 pole), I believe. And as noted above, the inverter mustn't attempt to change the frequency of all the generators in Australia
But wouldn't there be a loud hum in the garage for most of the night?
Yes, there will be the motor spinning. But you can use a separate inductor instead of the motor, or use one of the solutions that doesn't spin the motor.
Richo: The motor will have no torque with single phase applied and no capacitance to shift the phase of any other phases. It may hum fairly quietly, or possibly buzz due to the PWM through it.
Isn't isolation a big problem though? If you are charging from home you could have an isolation transformer, but carrying one in the car for a quick oppurtunity charge would be more weight.
An isolation transformer would be a show stopper, at least for me. But the motor is designed for connecting to three phase all day every day, so single phase should be no problem. The only issue may be the earthing; I would think that you simply connect mains earth to chassis earth and that's how the motor works normally in a factory.
For us in NZ you'd actually have issues getting the electrical certification for that ... esp with a pack voltage such as ours!
We have similar rules in Australia, in fact I think we share the design of these rules. So we'd have the same issues. I don't see that it's any more difficult than usual. Certainly any insulation failure would be a problem, and you can't earth the centre of the pack.
Coulomb, that's a pity you can't break up the pack and charge. But can't you still do it, albeit with perhaps some of the chargers being a different voltage? ie. match it to what ever size of battery you need? say you break up the pack into 48V modules in the back, but else where you work with 24V modules? ... it is still CC CV so they should all charge in the same time?
Yes, that's the fallback position I suppose. It might be tricky finding odd voltage chargers, and matching the (scaled) charging currents so they all finish at about the same time. But certainly possible.
Edit: leakage -> insulation failure
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.