A Silicon-Organic Hybrid Voltage Equalizer for Supercapacitor Balancing

Keshmiri, V., Westerberg, D., Andersson Ersman, P., Sandberg, M., Forchheimer, R., Tu, D.
Type of publication: 
Journal article

Cell voltage equalizers are an important part in electric energy storage systems comprising series-connected cells, for example, supercapacitors. Hybrid electronics with silicon chips and printed devices enables electronic systems with moderate performance and low cost. This paper presents a silicon-organic hybrid voltage equalizer to balance and protect series-connected supercapacitor cells during charging. Printed organic electrochemical transistors with conducting polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) are utilized to bypass excess current when the supercapacitor cells are fully charged to desired voltages. In this study, low-cost silicon microcontrollers (ATtiny85) are programmed to sense voltages across the supercapacitor cells and control the organic electrochemical transistors to bypass charging current when the voltages exceed 1 V. Experimental results show that the hybrid equalizer with the organic electrochemical transistors works in dual-mode, switched-transistor mode or constant-resistor mode, depending on the charging current applied (0.3–100 mA). With the voltage equalizer, capacitors are charged equally regardless of their capacitances. This work demonstrates a low-cost hybrid solution for supercapacitor balancing modules at large-scale packs.

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IEEE Journal on Emerging and Selected Topics in Circuits and Systems, vol. 7, no. 1, pp. 114-122
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DOI: 10.1109/JETCAS.2016.2612724