View Single Post
Old 05-20-2013, 07:29 AM   #7 (permalink)
MPaulHolmes
PaulH
 
MPaulHolmes's Avatar
 
Join Date: Feb 2008
Location: Maricopa, AZ (sort of. Actually outside of town)
Posts: 3,832

Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
Thanks: 1,368
Thanked 1,202 Times in 765 Posts
MPPT charger

I was thinking that MPPT was so complicated, until I realized, it's just a regular old buck charger! All you do (during the bulk charging phase) is adjust the PWM duty to maximize the output current! You don't need to maximize the product of the input current and input voltage (input power)! Just the output current! LEM Hass to the rescue! I think I'll sample current at a particular pwm duty.... Say, 0%. haha. I bet that will have a small output current. Then I'll just chase the higher output current by incrementing or decrementing the pwm duty to see if I need to hunt to the left or right for the global maximum. One problem with this is that I heard that there can be local maximums if panels aren't matched well. It's probably good enough to sweep through the whole range of 0-100% duty, and then assume that the global max you found can be kept in your sights by chasing it with the "increment/decrement pwm duty, and go in the direction of larger output current" method. haha that's a long name.
__________________
kits and boards
  Reply With Quote