I want design help to develop a transformerless output for 230VAC/50Hz pure sine Inverter with 24VDC/48VDC/100VDC input from batteries .
The base 5Khz to 50KHz oscill. pulse signals could be PIC16 based or ATMEL processor generated .
Timing generation will be one of the lesser problems, I assume. I don't think that it's a good idea, to design the inverter strictly transformerless. You would want to utilize a medium or high frequency transformer for effective voltage conversion.
There are some SMPS without use of transformers ( like Buck converter ); just the Inductor are used to performs reactive charge on capacitors. However like mentioned by FvM is not a recomended implementation and it is unnusual.