Embedded Real-Time Control for DC Multi-Converter Systems

Tightly regulated closed-loop converters are problematic when used as a load since they tend to draw constant power and exhibit negative incremental resistance. This negative resistance causes stability problems for the feeder system, whether it is an input filter or another converter. In multiconverter systems, there are many converters loaded by others. Therefore, the destabilizing effect of the load converters, which are considered constant-power loads (CPLs), is a major issue. In this paper, a novel nonlinear feedback control algorithm “Enhanced Modified Pulse Adjustment” is introduced. This technique is used to compensate the destabilizing effect of CPLs. xPC Target Turnkey is used for real-time testing and validation of the proposed controller design. Analytical, as well as real-time power hardware-in-the-loop (PHIL) simulation results of the controller rapid prototyping achieved constant output voltage regulation, while maintaining the system stability under different operating conditions sudden changes. Index Terms — CPLs, Multi-converter systems, Negative impedance instability, PHIL.