Generalized Carrier-Based Modulated Power Control Scheme for Asymmetrical Dual-DC-Port DC-AC Converter in Battery Integrated PV Systems

The asymmetrical dual-dc-port dc-ac converter features high integration, high efficiency, and low cost in battery integrated photovoltaic (PV) systems, due to the single-stage power conversion for PV and battery simultaneously. However, the voltage variation of both PV and battery causes the asymmetrical characteristics of the converters and leads to the difficulties of the modulation strategy. Moreover, the control target requires flexible regulation of the power flow among different ports within the single-stage converter. To address these challenges, a generalized carrier-based modulated power control scheme (GCBM-PCS) is proposed for the asymmetrical dual-dc-port dc-ac converter. The generalized structure contains the outer power control loop and inner modified carrier-based pulsewidth modulation (CB-PWM) with zero-sequence injection. The proper zero-sequence component is regulated by the outer power control loop. By introducing the asymmetrical carriers, the modulation is adaptive to the dc-port voltage variation. Besides, the relationship of the power distribution among different ports in terms of the variable dc-port voltages and controllable zero-sequence components of the proposed GCBM-PCS is quantitatively analyzed. The control algorithm is easy to be implemented by digital controllers. The effectiveness of the proposed power control scheme and modulation strategy is validated by experimental results.