Senior Member
Joined: 04/01/2008
Location: AlbaniaPosts: 510
| Posted: 08:35pm 27 Nov 2009 |
Bob,
Looking very nice! Will be following your experiments with interest. First DIY MPPT for wind that I've seen so far.
One thing though, you are driving the FET directly via an opamp, LF351. This opamp can supply only 40mA of drive current (according to the datasheet), which is too little to switch the FET hard on and off fast (which is a requirement for minimum losses and heating of the FET). I think I'd add a proper driver IC for the FET, either something like the TC4420 or at least a totem-pole circuit of complementary transistors (BC327/337; not perfect, but at least better than a direct opamp output).
There are specific ICs made only for the purpose of driving FETs, which can supply up to 6A peak, like the TC4420: http://www.datasheetcatalog.org/datasheet/microchip/21419b.p df
Looking forward to more details and pictures of your project. Would have expected MPPT for wind would at least need a PID controller. Maybe your controller is overcritically damped if you have no oscillation/hunting issues with the combination of MPPT and windturbine. Still, nice and simple design with obvious power harvest benefits, by the looks of it.
Peter.