Sparrow / NmG
Sparrow >> Modifications >> Kilovac Motor Controller Rebuild
My OEM Kilovac died recently. It was while a mechanic was driving my Sparrow trying to diagnose suspension problems. I suspect that he applied ample accelerator while moving backward, which is something that can tax any DC series wound motor controller. In any case, mine went up in smoke.
Most all controllers fail at low speeds. This starting condition is when a controller generates the most severe transient voltage spikes. These transients diminish as the back EMF increases with speed. These transients can stress power semiconductors badly, if the controller is hot the voltage transients can provide the straw that lets the smoke out.
Lots of low speed driving will prevent air being exchanged in the controller compartment. As the air exchange in the controller compartment is driven by the main motor fan. If the motor is driving the vehicle at low speeds the air is not being exchanged. At low speeds the currents are high in the motor loop and will heat the controller up. Installing a temp sensor on any motor controller so you can monitor temperature is recommended.
On a recent inspection of a Sparrow the air hose responsible for providing the air suction from the compartment to the main motor was found to split open, thus the air exchange was severely compromised.
I chose to have my Kilovac rebuilt rather than just installing a Zilla because I didn't want to heavily modify the control circuitry and because I figured that installing a water cooling system wouldn't be worth the hassle.
It was sent to Ron Anderson. You can reach him at:
Black Sheep Technology
102 Morgan Drive
Loveland, CO. 80537
He was kind enough to send me back some of the smoked parts for my entertainment:
While he was at it, he rebuilt the EVBC control logic box and added 20% more power silicon. When he was done, he re-did the sheet metal enclosure and added a fan so that it has forced-air cooling, rather than passive cooling with fans mounted near by (in some Sparrows.) Here are a couple of pictures of the results.