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need inverter: 24V to 115AC three phase, 100W

I need to build an inverter to convert 24V to 115V AC, three phase. The
load is a gyro, which is a motor, so I suppose its inductive. I dont
know if this means it needs to be a pure sine wave output or if it
makes it able to handle a square wave output or a sine wave with
harmonics. Anyone know what a simple way to make one of these might be?
Or an off the shelf unit?
 
D

Don Foreman

Jan 1, 1970
0
I need to build an inverter to convert 24V to 115V AC, three phase. The
load is a gyro, which is a motor, so I suppose its inductive. I dont
know if this means it needs to be a pure sine wave output or if it
makes it able to handle a square wave output or a sine wave with
harmonics. Anyone know what a simple way to make one of these might be?
Or an off the shelf unit?

The inverters I built to test gyros were all sinewave. I used a
shift register, then low pass filters and class B audio amplifiers --
brute force lab setup, not suitable for flight or robotic apps.

You might consider the shift register and LPF's (or a uP synthesizing
the three phases) followed by class D audio amps now available.
 
T

Ted Edwards

Jan 1, 1970
0
Don said:
The inverters I built to test gyros were all sinewave. I used a
shift register, then low pass filters and class B audio amplifiers --
brute force lab setup, not suitable for flight or robotic apps.

You might consider the shift register and LPF's (or a uP synthesizing
the three phases) followed by class D audio amps now available.

I have used a Johnson counter, a few gates, three opamps and a three
phase transformer (surplus) to produce three phase 400Hz 115V AC for
gyro testing. The wave form looks like:
----
-- --
----
i.e. 0 for 1/6, + for 2/6, 0 for 1/6, - for 2/6 of the cycle. Done
decently this wave form has no even harmonics and no third, nineth, ...
So the lowest harmonic is the 5th and it's already getting pretty small.
The transformer and gyro made no complaints.

Ted
 
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