Extending Dynamometer Performance for Virtual Engine Simulation

Dynamometer testing is a common means of investigating and validating automotive powertrain designs. However, the rotary inertia characteristics of the typical DC or AC dynamometer generally limit these machines to steady-state, block-cycle type testing; as a consequence, such systems are not particularly useful when studying the effect of engine firing frequencies on powertrain performance or vehicle NVH characteristics. Virtual Engine Simulation (VES) is a term used to describe a test system that replicates the speed, torque, and frequency characteristics of a fired engine in the laboratory using electrical and/or servo-hydraulic prime movers. VES systems have been shown to extend the capabilities of standard dynamometer testing to replicate engine-firing frequencies to a high degree of accuracy. The author contends that realizing a virtual engine system using existing dynamometer test systems is a cost effective means to improve and extend the overall performance of dynamometer systems.

This paper will discuss several topics relevant to virtual engine simulation realization including the definition of an “optimal” virtual engine simulator, a review of current virtual engine simulation techniques with particular advantages of each data to support the view that hybrid virtual engine simulation can simulate engine signatures accurately, and considerations associated with renovating existing dynamometers to support hybrid virtual engine simulation testing.