Hi Dayama,

I am sorry I couldn't be in touch as I am under terrible pressure handling some railway projects. I am a one-man army as you know.

Back to the topic:

1. Any improvement or innovative idea is welcome.

2. My sinewave inverter is running successfully (24VDC-240AC~50Hz) but cannot share the schematic and code as I am commercially bound.

3. Should there be any PIC related problem I will surely try to help within my knowledge boundaries.

4. I have already done a PIC16F676 based squarewave UPS design (inspired by a forum member) and currently testing it.

5. I am working with PIC16F73 to port my design of sinewave inverter into a small offline UPS.

6. Double conversion is okay but generally more complicated and may be expensive in terms of ROI. What I have found is that boosting the voltage from 24VDC to 384VDC (to create a 240V AC) is less efficient. May be due to my limited knowledge on designing sm transformer. A 48V DC based boost converter gives better result.

7. I would be working on a different technology from June onwards that promises to deliver sinewave output using a single stage and ferrite transformer. I don't know whether I would be successful there as it is my own project and have limited funding. If I can spent time and get some fruitful results I will post them here.

8. Regarding MOSFET drive what I have realised is that a soft turn-on reduces harmonics and a fast turn-off is necessary to cope for switching losses. Also ringing should be well controlled otherwise bursts for no apparent reason. And never use the Microchip drivers. They are real crap. I followed every guideline and got terrible results. IR, Toshiba great. In fact I asked in the Master's conference that why Microchip is using IR gate drivers on their dSPIC motor control board when they have there own product line.