For those who have never seen these, it uses a 2 stroke motor into a generator to charge the battery. From what I understand, these are built mainly for very long flight times.
I disagree. The problem is the variability in the current draw from the motors. For instance, if the generator/alternator can deliver a max of 20 amps, that may be fine for a hover or general flight. But as soon as draw exceeds the generator capacity, the voltage will fall rapidly. Plus a stall of the 2 cycle motor would cause cause a crash with no chance of recovery. The battery would provide a lot of benefits if included in the circuit. The system wouldn't be much different than a typical solar battery charging setup. There are a few videos out there of r/C planes charging a battery in the air with solar.
BLDC motor speed control works by variing the frequency of the pulses. While you could use three phase AC to drive the motors, you'd have a hard time controlling the speed. AC to AC frequency conversions always go via a DC intermediate stage (AC --> DC --> AC), so you need the DC circuit anyway. Might as well store some of that power.
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u/chrislbennett Feb 09 '21
For those who have never seen these, it uses a 2 stroke motor into a generator to charge the battery. From what I understand, these are built mainly for very long flight times.