Conductance Emulation Control for Real Power Compensation in Series-Stacked Active Power Decoupling Circuit

The series stacked active power decoupling (SS-APD) circuit is a power dense and efficient alternative for ripple energy storage in single phase power converter. The SS-APD circuit needs to absorb a small amount of real power to meet power losses in it. For this, the literature uses additional power supply or modifies the controller for SS-APD circuit. Such modified controllers require high bandwidth current sensing or noise-prone differentiation function. To address these challenges, this article proposes a conductance emulation control for SS-APD circuit. Here, the value of emulated conductance dictates the real power absorbed by the SS-APD circuit. It eliminates the need for differentiation function, dc-link current sensing and additional power supply for absorbing real power. Further, it uses feedback of dc-link voltage and enables independent control of SS-APD circuit from the single-phase converter. The proposed technique is investigated using state-plane analysis and small signal impedance analysis to highlight the design dependencies. In addition, the practical challenges such as proper sensing of ripple in dc-link voltage are also addressed. The load transient and steady-state performance of the proposed technique are validated by experimental studies with a 2 kW laboratory prototype.