The Christmas Controller

Over Christmas 2006 in Prineville, I put together a 1/4 scale IGBT-PWM controller using ten, 450W IGBTs. I aquired a chunk of stock Aluminum at the local metal shop, with a special thanks to Bill for letting me walk out the side door with $60 bucks worth of cold metal. Check out the camera phone picture of it on the right. It is essentially a Curtis 1505 PWM scooter controller, momentary "doorbell" switch, a 5K pot for speed control, and 3 x 10 Ohm resistors, which drop the PWM voltage by 2/3. The Curtis 1505 only works above 18V, so I plan on driving it at 24V with a gate drive voltage of 16V. The Thevinin equivalent voltage divider circuit puts 5.3 Ohms of resistance in series with 10 Ohm gate resistors. The power +V is common with the heatsink, so it "hops" to peak voltage (~140V) at the 18KHz PWM frequency. I plan on enclosing the entire heatsink it a clear Lexan tube and forcing air through it for cooling and safety.