Simulation of relay contact bouncing including a short arc model

The continuous growing requirements on power relays make it necessary to handle higher switching capacities which are represented in an increasing number of switching operations resulting in a demand for an extended lifetime of the relays. Especially by switching direct currents a directed material transfer which is limiting the lifetime can occur. Source voltage from battery systems (e.g. automotive) can scatter in a wide range due to the actual load condition. However several work principles of the relay are functions of the source voltage. Nevertheless the application requires a steady and secure switching behavior to ensure a high life-time. The authors present a simulation model (using MATLAB/ SIMULINK) describing a model switch based on a real application. It includes two different contact systems consisting two contact bolts and a contact bridge with a tilting movement. The geometrical dimensions including fabrication tolerances have been considered in the model. Three different electrical loads were investigated in combination with the model switch. A short arc model is created to simulate the current and arc voltage curves during the bouncing process. The evaluation and verification of the created short arc model is based on these three load characteristics. All simulations are validated by measurements.