50Hz power inverter for school project

[th3falc0n]

Hi EEVBlog Forum,

I watch EEVblog for a long time now and never decided to register here, but now I have to work on a bigger project, so I decided to finally register.

I have to (or rather want to) build a power inverter for a school paper. I decided to go with following specifications:
- 12V input voltage, 200W output power
- Mains controlled output (so it can be used to inject power into power net)
- at least OCP/current monitoring and temperature monitoring, and of course it shouldn't power itself from mains (turn off when no input power).
- stand-alone mode when not injecting power into mains

My current plan to realize this is as following:
- A seperated PCB for mains measurement with serial bus over a optocoupler to the main PCB
- 25-50kHz Class D amplifier with full-bridge and a filter like described in Figure 2 in this paper ( http://www.ti.com/lit/an/sloa119a/sloa119a.pdf )
- Output over a 300VA 230/18V transformer.
- ATmega644 as CPU, maybe with Ethernet for monitoring.

I am not sure about everything yet. Especially I don't really know how to realize the Class D amp, so this post is more a call for suggestions.

Some more specific questions I have are.
- How can I drive the full bridge? Is there a IC for driving a Class D full-bridge at 25-50kHz?
- What optocouplers are the best choice for say 9600 baud serial data?
- Is a Class D combined with the transformer suitable for power injection?

Thanks for any help,
th3falc0n