A PERFORMANCE COMPARISON OF TRACKED VEHICLE DYNAMOMETER SYSTEMS FOR MOBILITY LOAD EMULATION OF A COMBAT HYBRID ELECTRIC POWER SYSTEM

The United States Army Tank-Automotive Research, Development and Engineering Center (TARDEC) is actively researching methods to advance the state of hybrid-electric power system technology for use in military vehicles. Supporting this research, Science Applications International Corporation (SAIC) is the lead contractor for developing the Hybrid Electric Re-Configurable Movable Integration Test-bed (HERMIT), which is operated at TARDEC in Warren, Michigan. The HERMIT is a ground-vehicle-sized series hybrid-electric test-bed featuring a diesel engine, permanent magnet generator, high voltage bus, DC-DC converter, lithium ion battery pack, left and right traction motors, thermal management system, and left and right bi-directional dynamometers. The power system is sized for a 20-22 ton tracked vehicle. The dynamometers are responsible for emulating loads that the tracked vehicle would see while running over a military theater-type course.

This paper discusses the control system design for achieving mobility load emulation and compares experimental results obtained from two different sets of dynamometers running the same virtual course and duty cycle. Load emulation is defined as the ability of the measured left and right sprocket speeds to track the left and right sprocket speeds of the tracked vehicle model. The two types of dynamometers used to obtain the experimental results are an AC dynamometer and a DC dynamometer. The DC dynamometer has an inertia that is three times larger than the AC dynamometer inertia. The experimental results are analyzed with respect to the chosen duty cycle and the dynamometers used. Finally, the effect of the duty cycle on the dynamometer choice is discussed.