A comparison between different LCL architectures in space power systems

Latching Current Limiters are fundamental devices in satellite space power systems required to be Single Point Failure Free. They are used to protect and distribute power as described and required by the ECSS-E-ST-20-20C standard [1]. A crucial aspect of these devices is the current control loop aiming at limiting the current in case of overload or short circuit. On one hand the fastest possible response is required to LCLs when a load fault condition occurs; on the other hand a minimum stability criterion needs to be respected. This paper presents a comparison between three different topologies of control loop: the first one based on a resistive feedback with only a proportional action, the second featuring a topology based on an inductive feedback, with proportional and derivative action, and the third based on an Op Amp, with derivative and integral action. The comparison, mainly based on the ECSS standard, investigates both theoretical and experimental results. These latter derive from tests conducted on prototypes and/or boards intended to find application in space missions. The solution relying on resistive feedback offers a very simple and cost effective solution, while the architecture based on inductive feedback uses an inductor in series with the shunt resistor which results in a reduction of the Current Overshoot as practical experiments demonstrate. Finally, the Op Amp based topology offers a better control of the current limitation value over the other two solutions.