On 20/03/2019 16:38, J.B. Wood wrote:
Hello again, everyone.Â* I did some further online research and it
appears modern inverters use fast-switching insulated-gate bipolar
transistors (IGBTs) in sine-wave and modified sine-wave inverter
designs.Â* My guess is that a microprocessor controls IGBT firing times
as well as engine speed (in an inverter generator) as AC output loads
increase and therefore demand more DC at inverter input.Â* The
microprocesser itself would rely on a crystal as the reference time base
(frequency) source which would ultimately determine the inverter's
output frequency (e.g. 60 or 50 Hz +/- some acceptable deviation).Â* So
the crystal has to remain reasonably stable in a variety of operating
environments.Â* Sincerely,

After a quick google, I found this paper.

Design and Construction of 1kVA Inverter
http://www.ijeert.org/pdf/v2-i3/29.pdf

and also

250W PWM inverter circuit SG3524
http://www.circuitstoday.com/pwm-inverter-circuit


The mentioned IC SG3524 is primarily intended for DC-DC inverter
designs, and the oscillator is programmable by values of R & C.

TI SGx524 Regulating Pulse-Width Modulators
http://www.ti.com/lit/ds/symlink/sg2524.pdf

Although in the above two circuits, I see they set the oscillator lower
(50Hz) than TI's spec sheet (Sec 7.7 , Fig 2)


Have a look around for SG3524 schematics. It's popular!

3 High Power SG3525 Pure Sinewave Inverter Circuits
https://www.homemade-circuits.com/sg...erter-circuit/



--
Adrian C