Greetings, I am working on a basic buck converter for a permanent magnet alternator that will be driven by a vertical axis wind turbine to charge a 12 volt battery bank. A discrete dump load controller will be used to divert the load when the battery bank is fully charged. The open circuit voltage of the permanent magnet alternator can range from 0 to over 200 volts. Max current output desired is 15 amps. This is a first attempt and I am requesting information on a suitable gate driver for a synchronous two fet buck converter. Any information will be greatly appreciated.
The IR2117 seems to be a suitable gate driver for the application, so I would be more apt to suspect the oscillator circuit of causing your problem. If you have access to a signal generator, you might try using it to supply a cleaner waveform to you gate driver's logic input, and see if this resolves your issue.
Also, many semiconductor companies offer integrated Buck controller circuits. Using one of these controllers could save you quite a headache, as they act as oscillators and also use voltage feedback from your Buck's output to alter the duty cycle of the waveform, ensuring a better-regulated output.
If you need some good references about Buck design, the best one I have found was an old TI paper from about 10 years ago, titled "Under the Hood of Low-Voltage DC/DC Converters". Try googling it, because I'm having trouble linking directly to the PDF file.
Also, here's an article about the various methods used to reduce the ringing at the source of the switching FET, while also explaining some of the causes: http://low-powerdesign.com/article_tamingthebuck_082510.htmlebuck_082510.html
Hopefully this could be of some use to you. Good luck!
-Alex