Abstract
The conventional full power converter (FPC) for battery energy storage applications is limited by bulky components and suboptimal efficiency. In response, a series-connected step-up/down partial power converter (SUDPPC) with high power density is proposed in this paper. It consists of an LLC resonant converter operating at a fixed switching frequency cascaded with a full-bridge converter capable of providing bipolar output. By connecting the SUDPPC in series with the load, the voltage stress on the series side and the current stress on the parallel side are markedly reduced. The four-quadrant function provides support for further optimization of the rated power level. Universal series interconnection schemes are elaborated, and design guidelines are formulated based on power distribution characteristics. Furthermore, the topology is evaluated in terms of nonactive power and component stress factor (CSF), and benchmarked against a four-switch buck/boost FPC and a phase-shifted full-bridge step-up partial power converter (SUPPC). Finally, a 1.1 kW prototype is developed to experimentally validate the theoretical analysis, demonstrating that only 14.3% of the total active power is processed under full-load conditions, with a peak efficiency of 98.15%.
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Abbreviations
- V dc :
-
Dc bus voltage
- V b :
-
Battery voltage
- V 2 :
-
SP voltage
- ΔV :
-
Bias voltage
- I dc :
-
Dc bus voltage
- I b :
-
Battery current
- I Lm :
-
Magnetizing current
- I Lf :
-
Filter inductor current
- ΔI Lf :
-
Inductor current ripple
- P p :
-
Processed active power
- P d :
-
Direct infeed active power
- P max :
-
PPC maximum power
- P out :
-
Output active power
- f s :
-
LLC converter resonant frequency
- t d :
-
Dead time
- f c :
-
FB converter switching frequency
- C oss :
-
Output capacitance of the switches
- C r :
-
Resonant capacitor
- L r :
-
Resonant inductor
- L m :
-
Magnetizing inductor
- d :
-
FB converter equivalent duty cycle
- n :
-
Transformer turns ratio
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Funding
This work is supported by the Shenzhen Science and Technology Plan project (The key technology research and development of MWh level battery energy storage cluster balance control system, KJZD20230923112959001).
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Q. L.: Data curation, Methodology, Software, Writing-original draft. L. J.: Writing-review & editing. W. X.: Writing-review & editing. R. S.: Writing-review & editing. X. W.: Writing-review & editing. J. L.: Writing-review & editing. Y. Z.: Writing-review & editing. All authors reviewed the manuscript.
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Liu, Q., Jing, L., Xu, W. et al. Performance evaluation of a series-connected step-up/down partial power converter for battery energy storage applications. Sci Rep (2026). https://doi.org/10.1038/s41598-026-35857-z
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DOI: https://doi.org/10.1038/s41598-026-35857-z
