Dummy load for brushless motor controller

Dummy load Jig Complete

Dummy load Jig Complete

Here is a little jig I made to test and characterize the BLDC controller I wrote about a while back. It is a dummy load consisting of two coupled motors: one driven by a controller and another having its windings shorted either directly for maximum load or through series resistors when measured load is desired. Title picture shows finished jig (click on it to make it larger). The construction details follow.

Two brackets made of 2″ aluminum angle profile hold 50-size brushless outrunner Chinese motors rated at 100A. The brackets are bolted to 0.5″ polycarbonate base. The motor shafts are coupled with a flex coupler. Finally, the contact plates are bolted next to each motor – this way if I burn a motor, changing will be easy. The high-current wires are soldered to the female contacts. I’m using double wires to increase current capacity of the wire and also to allow observing half of the flowing current with my little 50A current probe.

I tested the load with my prototype BLDC controller and was very pleased with results. The testing is documented in the short video – check it out.