A friend of mine recently picked up two high-current motor controllers with the VNH2SP30 chips on them. The motors are 12V and no-load idle somewhere around 5-6A. They haven’t been stall tested yet, but from the data sheet my friend is figuring around 14A, possibly a little more. Power is being supplied from a pair of 12V 13Ah NiMH batteries, so the supply can keep up.
So here’s the question: How do you heat sink the VNH2SP30 chip so it doesn’t turn into a black hole?
FWIW this is only my second exposure to DC motors this size. The other ones were spindle motors for some small machine tools running off of KBIC-120 speed controllers, which turn 110VAC into 90VDC and involve large blocks of aluminum as heat sinks.
More or less we were planning on doing something similar: Mount the headers for the high current motor controller on the back side of the board, apply heat sink compound to the VNH2SP30 chip, and use the board’s mounting holes to bolt it to the aluminum frame, using the frame as a heat sink.
Would we do better using a finned heat sink? It’s possible to add fans for forced cooling, but the device is going to be exposed to a lot of dirt and grit, so a fan may not last long.
Could we get something like a Bud or Hammond die cast box and mount the motor controller inside, using the box itself as a heat sink? It’d be nice to protect the boards from the elements. They’ll be used outdoors.
My friend is doing all the design work on the project. I’m tagging along to do some of the mechanical fabrication, and to be someone he can bounce ideas off of. The last thing either one of us wants is to let the magic smoke out of either of these. But it’s doubly bad for me since they’re not mine. I’d hate to fry his hardware because of my ignorance.