Torque Spike Analysis of an AC Haul Truck Traction System

The mining industry has requested large capacity haul trucks with low maintenance to improve operating costs. To satisfy this request, diesel-electric drive systems have evolved from DC to AC control systems. AC drive technology offers high efficiency, low maintenance costs, and many advanced features over DC and mechanical drive technology.

The use of AC inverters introduces the possibility of high current spikes to the motor during a two or three phase short circuit. This failure mode results in a large negative torque being generated in the motor that resonates until the current dissipates. This paper studies the effects of this spike on the electrical and mechanical system covering both analytical and field test results.