Susceptible Frequency Range Definition for Robust Immunity Tests

Systems containing lithium-ion batteries are shown to require a longer dwell time to properly perform an immunity test due to their vulnerability to thermal runaway effects. Since thermal processes generally take longer than the standards require for testing, the need for longer dwell time can easily be overlooked. This paper highlights the procedure to estimate the narrow frequency band in which such equipment is the most vulnerable to disturbances, and where longer dwell time should be used. This paper discusses different approaches for determining such a frequency range. In particular, the approach utilizing input impedance measurements is examined in the case of a device containing a lithium-ion battery. The analysis is performed on a simulated circuit as well as based on measurements of an assembled unit representing complex equipment under test.