Hi Mincing,

I was too busy in a project and really coudn't get the time to reply to the thread.

1. For the driver part I use TLP250 from Toshiba. Get the datasheet and everything should be easy.

2. For the bridge you would be using all N-Channel Mosfet perhaps cause they are readily available and have much lower Rds On compared to P-Channel. However switching the high side MOSFETs are a little tricky. You need to have a charge-pump circuit to switch them on. Try the IR2101 it makes your design much easy.

3. To maintain low distortion in the output use a flux reset method when changing cycle. You do this by turning of the high-side mosfet, then turning on the other low side mosfet (both low side mosfets on) and then turning off the one which is not required for the current cycle and finally starting the high side driver of the corresponding cycle.

4. Please note that keep your high-side MOSFETs turned on during the entire cycle and apply PWM to the low side MOSFET. Initially I tried steering the PWMs to all of the four MOSFETs to make up for the conduction switching loss. But it did not produce satisfactory results.

5. Now for the transformer design. Say you are operating on a 12 volts battery. Now when the battery is full charged it is upto 13.8 volts nominal and before the deep-discharge of at around 10.8 volts. You can reduce the voltage with PWM but cannot increase it with the current scheme (boosting can be done, theoritically using a boost PFC like technique but I failed to do so). So keep your transformer primary at around 7.5 to 8 volts. This accomodates conduction loss, battery low, and so on.

6. Now the problem is that the same transformer is being used for charging and you need to boost the voltage during charging. Well a PFC boost method can be applied. See the attached PDF. Note the high side rectifiers are your high side mosfet's body diode.

I am attaching a few more documents links which can be handy during the design process. Sorry for Rapidshare. The documents are more than the allowed 200kb and a multipart zip/rar would have been around 10 parts.

Here are the document links:

http://rapidshare.com/files/34936881...r_with_PFC.pdf

http://rapidshare.com/files/34936883...ter_Design.pdf

http://rapidshare.com/files/34936882...c-inverter.pdf



I am sorry I may not be able to provide active support on this thread due to time limitation but will always try too within my knowledge and scope. (I am a completely self-taught with little or no academic background, So I might not be accurate all the times and ready to learn from others.)

I may start up a project on high frequency double-conversion sine wave inverter that utilizes Ferrite Core Transformers as PsDayama suggested. However it would be based on the dsPIC 30F2020. I still don't know whether I would be able to take up that project. Cause I have very little time left for myself catering to clients.

Anyways its good to see that the thread is alive again and would refresh my knowledge base.