Voltage regulator (VR) efficiency improvement especially at light load currents is important in many applications including those that are battery powered and have energy consumption constrains. However, controlled steady-state and dynamic performance should be maintained while improving efficiency. In this paper, an analytical study of VR losses and voltage ripple deviation is presented and discussed, yielding to proposed control technique, namely "pulse sliding" (PSL) control technique, which results in improved VR conversion efficiency with low and controlled voltage ripple and improved dynamic response. The proposed method and controller achieves the advantages of both variable frequency and fixed frequency controls and eliminates their disadvantages by utilizing information obtained from the inductor peak current, compensation error signal and capacitor current, resulting in an optimum nonlinear switching frequency modulation. PSL is compared to other control methods by both analysis and experiments. Experimental results highly agree with theoretical analysis.
This paper proposes a novel converter topology that interfaces four power ports: two sources, one bidirectional storage port, and one isolated load port. The proposed four-port dc/dc converter is derived by simply adding two switches and two diodes to the traditional half-bridge topology. Zero-voltage switching is realized for all four main switches. Three of the four ports can be tightly regulated by adjusting their independent duty-cycle values, while the fourth port is left unregulated to maintain the power balance for the system. Circuit analysis and design considerations are presented; the dynamic modeling and close-loop design guidance are given as well. Experimental results verify the proposed topology and confirm its ability to achieve tight independent control over three power-processing paths. This topology promises significant savings in component count and losses for renewable energy power-harvesting systems.
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