Vehicle Powertrain Systems

Appendix

An Introduction to Bond Graph Modelling

A. 1 Basic Concept

The basic concept in bond graph analysis is to specify the flow of energy in a system. The energy flow in any system is always governed by simultaneous intervention of two independent parameters. In the bond graph method these two parameters are defined by the general terms of Effort e and Flow f. The power of the instantaneous energy flow is product of these two factors:

(A.1)

Momentum (p) and Displacement (q) are defined as:

(A.2)

(A.3)

Therefore Energy (E) from Equation A.1 is

(A.4)

An energy port in a bond graph is the gateway for energy exchange. Should an element exchange energy in a single way (e.g. heat) that element is called a one-port (or single-port) element. A multi-port element, therefore, is an element that exchanges energy in different ways (e.g. heat, electrical, mechanical, etc.).

A. 2 Standard Elements

The elements in a bond graph are models of components in real systems. As far as energy is concerned, an element of a system is either a source of energy or consumes energy. Consuming energy may result ...