Passivity-Based Stabilization Method for a DC Power Supply System with a Constant Power Load and an LC Filter

This paper proposes a passivity-based stabilization control of a DC power supply system by feedforward control to improve output frequency impedance characteristics which satisfy the Nyquist stability criterion. The principle is that the output impedance is designed to be passive and the system is sufficiently stable for any filter impedances. The new design principle for the proposed stabilization method mainly consists of three steps. At the first step, the state feedback control gains with a mitigated integral compensator are designed to have a good response characteristic according to the optimal control. The designed characteristic of the output impedance may not be passive at a lower frequency band. At the second step, a resistive characteristic is added to the band by a new feedforward control design based on a fitting method to make the total characteristic passive and to ensure stability. At the third step, correction coefficients are tuned to eliminate a deviation between measured and reference output voltage values at transient operations. The method is investigated and validated to be passive and stable by simulated and experimental results.