Transient Stability Testing of Transmission Line Fed LED Driver

This is a companion example to the design: "TDFS Impedance Stability of Transmission Line Fed LED Driver - Switching". In this version, a switch is added to turn on two of the LEDs after 2 ms, to inject a load transient into the system. This transient will expose the severity of the damped ringing response at the converter input, or system instability if the source/load impedance ratio is inadequate.

The initial configuration for this design uses a cable length of 400 meters with 8 AWG = 2.1 mOhm/meter conductors, and a converter input capacitor = 22uF. This is consistent with the companion design. You can try using an increased cable length (e.g. 800 meters, 5 AWG = 1 mOhm/meter) by making a copy of this design and re-running the simulation. You will see that the circuit becomes unstable at that longer length. You can also try larger values of input capacitance, to mitigate the instability problem.

Mike Donnelly's picture



Mike Donnelly

Joined November 8, 2013
Design added Tuesday, February 21, 2017 | 8:38 am PST