Thx for the link to that SPWM controller board Harvey. I have ordered the board and the FETs. I will do a open source Hackaday project on it as a laminator speed control as I get time. It seems all I need to add would be the 170VDC to obtain the 120VAC (170VDC RMS). I plan to do that by using an old PC PSU to supply the 170VDC (internal tap) and the 5VDC & 12VDC.
As a project I may do a dedicated PIC microcontroller speed control with everything integrated (including a voltage doubler for 220/240VAC motors) as a 'safe' kit to build to deliver the 200mA capability to handle a wide variety of small synchronous motors. Probably housed in a 4" x 2" PVC electrical can with a couple LEDs for status displays.
It seems that most AC Synch. 'spare part' motors come in the 220V variety.
As I consult for a CNC machine shop company that makes gears, I can inquire as to making a batch of gears, standard size for laminators and such with set screws. Maybe 6061 aluminum would be durable enough, but certainly mild steel is doable. Oil impregnated bronze might be available.
These two link,below, on youtube help demo the board and demo how a micro does the job as well..including theory, BASIC code & wiring.
Demo of the sine wave PWM inverter board
https://www.youtube.com/watch?v=gtmYnbtcPVg
Use a micro to create the sine wave PWM to drive an H bridge
How to implement an sPWM on arduino/atmel (sinusoidal PWM code and explanation)
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