Analysis and Design of Single-Phase Grid-Connected Battery Inverter Using Dual Active Bridge DC-DC converter

Abstract

Combining residential energy storage with solar photovoltaic (PV) power generation within low-voltage distribution networks holds promise for attaining energy self-sufficiency. This research presents the design and implementation of such an approach using a 3-kW single-phase grid-connected battery inverter. The inverter pairs a 51.2-V lithium iron phosphate battery pack witha 220-V, 50-Hz grid. Its prototype design incorporates both an LCL-filtered voltage source converter (VSC) and a dual active bridge (DAB) DC-DC converter, both operating at a 20 kHzswitching frequency.

The VSC employs a swift DC bus voltage control strategy alongside a comprehensive approach to mitigate current harmonics. Similarly, the DAB DC-DC converter integrates a proportional-integral regulator to efficiently manage the average battery current, incorporating dynamic DC offset mitigation for the medium-frequency transformer’s currents within its single-phase shift modulation scheme. The control strategies for both converters are executed on a 32-bit TMS320F280049C microcontroller within the same interrupt service routine, demonstrating the integration of control systems to enhance performance. This study introduces a synchronization technique aligning the switching signal generation of both converters with the sampling of analog signals for the control system, ensuring coordinated operations.

The prototype inverter exhibited exceptional performance, achieving an efficiency exceeding 90% and maintaining total harmonic distortion in the grid current below 1.5% at a battery power output of ±1.5 kW, suggesting its potential to enhance grid stability and energy efficiency.

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