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Variable-Speed Motor powered by 400Hz 3-phase
Need advice to find a variable-speed motor (about 40 or 50HP) and motor controller to be powered by 3-phase 400Hz aircraft generator set. The purpose is to power a small vehicle.

I have acquired a turbine-powered GPU with the intention of adapting the unit to motorize a small vehicle. While I know that the turboshaft of my GPU, which spins at a manageable 3,000 RPM, could easily be coupled to a rather conventional transmission, I am entertaining the idea of using the GPU 400Hz generator to power electric motor(s), which would be mechanically coupled to the vehicle's wheel(s). With my mechanical engineering background, I am not fully knowledgeable to judge the feasibility of this project. While I feel confident that the idea is doable (i.e., there should be no absolute technical impediment), I am not sure of the level of difficulty (and costs) associated with the variable-speed motor control and the motor itself. I would appreciate if someone could provide me with his/her technical opinion about this possibility.

By Anonymous on 2 March, 2006 - 11:43 pm

Then you need a motor which works at 400Hz for its rate value.

I would like to ask why does the aerospace field use 400Hz...

what are the three phases? on the ext power there is three phase two long and one short. why the short?

I can't comment on the long vs. short phase question, but, in general, 400 Hz is used in a lot of military gear for space and weight savings, and because its easier to create low ripple DC from higher frequencies.

I would suggest using Variable Frequency Drive. A VFD rectifies input power to a DC buss voltage of 325 or 650 volts depending on whether the source is designed for 230 V single or three phase or 460 V three phase. Most VFDs provide three phase output of 0 to 400 Hz with a programmable torque or current profile to drive an AC induction motor. These drives also provide reversing and usually several interlock and speed control options. One thing you will need to figure out is how to provide control power for the microprocessor circuts since these are usually fed from a 60 Hz control transformer across two input phases inside the unit. Note: don't modify or apply power to the VFD unless you understand what your doing. 480 V can make a very big bang!

By Robert Slate on 23 June, 2006 - 12:06 am

I've looked at doing the same thing and have a lot of experience using standard Variable Frequency Drives (VFDs) outside of thier design use.

While you can probably just input the 400hz AC supply into the VFD I'd reccomend converting it to DC first and then putting it to the VFD.

Then use the VFD to drive a motor normally. Higher voltage and 400hz saves weight and improves transmission needs while a permenant magnet (read "Servo") motor may provide better regen.

Also consider a load bank to dump energy as heat.

Good Luck,