creating PWM sine wave (variable freq. AC power supply)

[petrv]

Someone suggested modified sinewave inverter could work - it does not work, experimentally verified. I have verified that 50 Hz sine wave (obtained by step-down transformer from 230V/50Hz mains) does not work (but I knew that it would not) and 60Hz modified sinewave inverter does not work with it as well ... the module powers up and communicates with my PC over RS232 serial port correctly but the powerline communication does not work (which is not suprising). I have created voltage divider with 2 resistors (220k + 2k) and connected the oscilloscope probe to the 2k resistor - the inverter outputs a square wave.

So I have just confirmed I really need 115V/60Hz true sine wave - I can go back to my inverter experiments.

 

[mneary]

So you not only want to supply power to the insteon unit, but it also has to have a communications bridge to the mains?

 

[petrv]

Exactly. I have it plugged in an US outlet strip and I want to be able to control the other modules ... and it DOES work with true sine wave inverter, at least the one I have built yesterday. I have it on a breadboard (I know it is not a good idea to do power electronics on a breadboard but this is really a low power for a power el. circuit).

I have used dsPIC33FJ16GS502 MCU connected to HIP4082 full bridge gate driver driving 4 MOSFETS 60V 16 A (STP16NF06 - I had them already so I used them), output connected through 2 power inductors 250 uH to 4.7 uF capacitor and a step-up transformer and I got a nice 60.1 Hz sinewave on the transformer output

It does not have output voltage sensing circuit (yet) so the load regulation is very bad
and no overcurrent protection but otherwise it works nicely

Petr