Study of system instability in current-mode converter power systems operating in solar array voltage regulation mode

Abstract

A study of power system stability, based on analytical modeling, is presented for application to a current-mode DC-DC converter power system with a solar array input and a line-filter interface. A fundamental analytical background is provided for use in analyses of systems of similar architecture. With this architecture, there is a potential for two sources of instability: (1) the relatively high-Q resonant tank formed by the input filter inductance and the array capacitance combined with excessive array voltage regulation loop-gain; and (2) positive feedback due to in-phase response produced by the current-mode converter at low frequencies. Such a low-frequency instability is dependent upon the magnitude of the array current, the array impedance, and the array voltage regulation loop-gain.