# VFD? to power aircraft non-motor/inductive load OR power conversion [closed]

QUESTION: Is it plausible to test power, out of aircraft, a mostly solid state device ie Microwave Oven? Can a VFD be programmed to run with inverter circuits. If so, 3 phase + ground output of VFD is 4 wire load compatable? PHOT0 1 vfd

POWER SOURCE, VFD = 1.5kw 1ph to 3ph, Chinese manual only, seller mistake

LOAD, Aircraft Microwave Oven = 1.5kw 115v 4 wire 3ph 380-600Hz power requirement

BUDGET $1000~ yes you can spend$20,000 for a ground support generator

Load design, aircraft microwaves have a entirely different primary power design. 3 phase 400hz power is fed thru a RFI line filter for each phase. This power then goes thru power conversion mosfet circuits and AC to DC inverters. Anything to avoid using a transformer. Only one conventional transformer is used to power the magnatron filament, not counting the switching xformers on the boards.

UPDATE METHOD to power 115vac @400hz 1500va Oven Super advice. Yes the maximum power consumption is 1500W, the intent was to power up and check the brains of the unit with the 1500va VFD and not cook. I have now repaired a 1968 Unitron frequency converter. Producing 2000vA 3ph-200ac in /2 ph-115 out @400hz. The QUESTION now is the oven requires 3ph at 115v, I have only produced the 400hz variable. Im already fooling the frequency converter with "fake" 3ph (3phase motor/cap running off 1ph 220v). Based on the schematic attached, how would it be possible to make "fake" 115vac power?

This is the 3ph Power management schematic.

## closed as unclear what you're asking by Eugene Sh., RoyC, Finbarr, Techydude, Sparky256Mar 5 '18 at 5:22

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• VFDs depend on the motor inductance to smooth the output PWM waveforms. – Spehro Pefhany Feb 28 '18 at 22:21
• Your question is very confusing. However if you are wanting to ground test aircraft equipment then a comfotably over rated VFD set for 400Hz output and the correct voltage should work as a decent ground source. A suitable three phase 400Hz 1:1 transformer after the VFD would help smooth the harmonics a bit. A resonant circuit might help even more. If you are planning something else please clarify. – KalleMP Mar 4 '18 at 9:02

This is very unlikely to work well.

Figure 1. PWM approximation to a sine wave. Source: VFDS.

VFDs use PWM from their internal DC bus which in turn is full-wave mains and will be close to $\sqrt 2 V_{RMS}$. A motor can tolerate this as its inductance will act as a low-pass filter. Your microwave oven, more than likely, will not tolerate it.

You probably require a 400 Hz sine inverter for the task.

You aren't specifying the surge load current and effects on load regulation of a VFD, so I would get something with twice the current rating. Your steady current is only 13A @400Hz 3ph @115V. If you are doing qualification or design verification tests, you will need a reliable pseudo sine source to simulate plane generator. So ask supplier about THD.

May or may not do the job

Below may be a better option with 34A if you can supply 220V

• Yes the maximum power consumption is 1500W, the intent was to power up and check the brains of the unit and not cook. I have now repaired a 1968 Unitron frequency converter. Producing 2000vA 3ph in /2 ph out @400hz. – Mark Laba Mar 5 '18 at 19:31