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Old 04-16-2019, 09:10 AM   #3427 (permalink)
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Originally Posted by Quattro64 View Post
Thanks, Is it Volts or Current that I would combine, in parallel?, to increase power when I want to add battery boost? I imagine I'd need to do this prior to the controller(s) via high voltage relays or something. Is this the way I would go about adding boost to a Series Hybrid EV?

I only need to size the ICE HP to the correct sized AC Generator that would then provide converted DC to the Controller/Battery charger to both charge the batteries, preferably on the ground, and drive the AC propeller motor with decent cruising speed/power. The Battery bank would only need to be sized large enough to provide boost power when summed with the motor power or to keep the plane in the air if the motor should fail. I think this is all doable just need to crunch numbers before I start writing up any white paper.

Do you have any connections to aircraft design world? I mean are you AML licenced or aircraft design engineer?
Have you made a performance comparison of Emrax package with particular battery versus Emrax + smaller battery and motor generator package?
Aircraft wing loading, takoff and landing performances, mode of operation etc...

I may have some insight for you.
- Calculate airplane rated power as the 75% rating. This is the power airplane will fly most of the time at. Also this it the power motor has to be able to sustain indefinitely, not just the measly 1hr rating industry offers as continuous rating. For climb and takeoff performance you calculate 90% *1.2 and you get the max power you need. 100% is emergency power for climbout at MTOW and high altitude etc...

- Emrax motor is very power dense. However it is 20pole motor. Control has to be performed at high PWM like 18kHz and this is difficult to achieve at high amps. Emsiso is good controler up to 120Vdc i am not sure they can provide 400A rating for extender period. 800A is peak power in cold state.

- Diesel genset can be quite heavy. How about a lighter 4cylinder engine like Rotax 912? If you use cooling system i recommend using one for the whole system. This is difficult with power electronics limits at 80C.

- In airplane EV world Amps mean weight. More amps, more ohm heating, heavier cables, heavier cooling system You want to lighten current demands as much as possible. I would suggest to go to 360Vdc system. It is the best tradeoff performancewise.

- You can use diode bridge directly with Emrax. I have tried this. It gives voltage linear with rpm. LV motor/gen would give 360Vdc on bridge with something like 4000rpm. This is slightly out of phase, that s why you have to use a battery or supercap in the network if you want to supply the propulsor Emrax directly then.

What you can think about is:
1. Front drive LV Emrax 120kW (75% derated) with 200kW (100% rating also derated)
Consider if you want to use 2:1 gearing to lower prop speed from 4000rpm to more acceptable 2000rpm.

2. Volt inverter is rated up to some 400Vdc with 600Amp IGBTs. What is better it has dual 3phase bridges which are connected to the same DC link! What i suggest is using that, genset provides steady supply for continuous use and battery provides power to supply peak demand at takeoff and heavy climbout.

3. Battery has to be designed to be small enough but able to supply peak current demand. Supercap system is unobtanium for this kind of application.
Your best bet now are hybrid batteries. I saw Volvo V60 and XC90 hybrid batteries are particulary light. Also Lexus models with 3x engines may use powerfull inverters and may even use 600Vdc system.

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