I need help designing a 400hz 115vac 3phase power supply -- Help

Thanks for the synchro explanation. Interesting stuff.

As it's your own gear, can you dismantle the single phase gear and see if there is a switch mode power supply in there.  If they are SMPS, regular 60Hz, or DC will probably be fine.  SMPS have a rectifier as the first component, so they don't really care what you give them.

I read a few specs for synchros (Moogs).  They need a small amount of power say 100mA - do you have the spec.  This makes life safer and easier.  The other thing I read is you can half the frequency and half the volts without affecting the accuracy too much. I'm out on a limb here, but it looks like they are tolerant of less than perfect 3 phase, so if you didn't have exactly 120 deg separation, the error is minimal as both RX & TX cancel the error.

Staying with 3 phase, I think you can do it with a stereo class D amp (say 20W) ie 2 channels. Class D simply as you'll have less heat to dissipate and you can probably dispense with filters on the arduino output & amp input. Create 2 pwm outputs 120 deg apart, 1 wired to each channel. The output from channel 1 is put through a handmade step up transformer with 2 x 115V output windings.  Wire these back to back to create 115V 2 phase, separated 180 deg. Output 2 is wired through a similar transformer (easier to make 2 identical, but not important) and wire the secondary up to the first in the correct sense.

As your current demand is small, I imagine the single phase loads, distributed over the 3 phases, will not cause too much voltage influence, so you may not even need feedback. I seem to remember aero stuff keeps going under tough conditions.

If it wasn't for the 3 phase loads, 25V/400Hz would be quite easy - wouldn't even need a step up transformer, or a PWM signal - just a couple of logic chips.

I have a gut feeling the synchros wouldnt work with MC33035 stepped output, or would run warm. Good idea all the same.

A hacked low frequency ie heavy UPS would be very lossy in the transformer (or make a new one).  A high frequency UPS might work.  Swap the main crystal out and change the output filter.

Nice piece of kit.. you got a hell of a deal..

shipping from across the pond would kill me..

LOL 

BTW  I think what im going to do I buy a few small Arduino's ~1" x 2.5" and run them at 400hz (PCM) or 1 triggering 2 others

so that the master or #1  is 400hz at 0 deg.;

#2 and #3 triggered from the master at 0 crossing. where

#2 is at 400hz at 120 deg from #1 and

#3 is at 400hz at 240 deg from #1.

Then run everything through some H-bridges.

or even an audio transformer..

In order to cause synchros to follow each other only one phase of excitation is required. The excitation ac is applied to r1 and r2 of both the transmitter and reciever synchros. The stators, s1, s2, and s3 are connected to each other in that order. Rotating one of the synchros will cause the other to follow. The three phases you speak of are produced within the windings of the transmitter synchro. In synchro driven motor devices the excitation is provided only to the transmitter. The output from the rotor of the reciever is fed to a servo amplifier which drives a motor to move some object which is linked to the shaft of the reciever synchro. The motor drives the object until the output from the reciever reaches null,  which may be zero voltage or zero phase difference, compared to the excitation signal.

The reason 400Hz is used for aircraft equipment is that the size and weight of the devices is reduced greatly compared with 50 or 60Hz devices.

Telonic sell them if you cant get anywhere with your design, see AC Power Supplies

Doug, Thanks for chiming in.. Looks like a nice piece of kit, but on the pricey side.. I have to do this on the CHEAP as I am broke (well almost).. LOL ~ Cris

Cristina, you could use a kit like this to get the basic control but boost up the output drive to reach the voltage you want. However it may be best to learn with this kit and develop your high volts skills as a second step.

Three Phase BLDC Motor Kit with DRV8312 and Piccolo MCU - DRV8312-C2-KIT - TI Tool Folder

A more complete kit would be:

DM300021 - MICROCHIP - POWER MODULE, DSPICDEM, MC1H, MOTOR | Farnell element14

Peter

or, if you wanted something very simple, you've been suggesting an Arduino solution, you could derive a 3 phase logic signal with 3 logic pins and apply them to a  high voltage opamp on each phase via AC coupling and a bit of filtering. (The supply would have to provide current limit.)

Once you got this working you could boost the voltage too on the output stage.

Hi.

Like so many before me I am try to build 3 phase 115v, 400Hz supply to drive an ex-aircaft gyroscope (or two).

My starting point is this ready made module

http://www.bldcmotor-driver.com/sale-11361290-110v-220v-ac-input-stepper-motor-driver-board-high-voltage-motor-control-board.html

which comprises a JY02A Sensorless brushless DC motor control IC

https://docplayer.net/146908738-Jy02a-sensorless-brushless-dc-motor-control-ic.html

and a JY213 Motor Driver MOSFET / IGBT Driver High Speed 3 - Phase Half - Bridge

http://www.bldcmotor-driver.com/sale-11344385-jy213h-bldc-motor-driver-mosfet-igbt-driver-high-speed-3-phase-half-bridge.html

To give these old gyros the easiest possible life I would like the drive waveforms to be as close to sinusoidal as is realisticaly possible so I am envisgaing incorporating 400 Hz L/C low pass filters between the output of the drivers and the gyro windings.

I have looked at various LC filter design tools such as

PI Filter      http://www.calculatoredge.com/electronics/ch%20pi%20low%20pass.htm

Chebyshef  https://rf-tools.com/lc-filter/

and understandably all of these design tools require a source and load impedances to be specified.

In my application the source impedance will hopefully be very low, and I have no idea what the gyro winding impedance will be when rotating.

Please can somebody suggest the best way forward, or point me in the direction of some helpful documentation?

Many thanks

Alan K. 

Hi Alan,

I think it's not required, an example is BLDC motors themselves, they are expensive but do not get damaged by electronic switching of voltage across the windings. Same with hobby CNC that uses stepper motors. PWM'ing of motors is very common too, although that's at a higher frequency. The current will change linearly through the coil windings due to their inductance, and this will self-smooth. If it doesn't, you can add an extra inductance in series with the winding.

peterjcs23 They are way to expensive..