Supercapacitor-assisted low dropout regulator technique: a new design approach to achieve high-efficiency linear DC–DC converters

Supercapacitor-assisted low dropout regulator technique: a new design approach to achieve high-efficiency linear DC–DC converters

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Approximate efficiency of a linear regulator is given by the ratio of regulated output voltage to input voltage. Higher voltage difference between the input and the output means a lower efficiency due to heavy losses in the series power semiconductor. Supercapacitor-assisted low dropout regulator (SCALDO) is an emerging linear DC–DC converter technique, where a supercapacitor (SC) is used to reduce the voltage drop across the series transistor in a linear regulator where the SC acts as a lossless dropper. The circuit operates at a very low frequency decided by the size of the SC. An efficiency multiplication factor such as 1.33, 2, or 3 is achieved depending on the configuration. This study presents the essentials of its generalised theory, few prototype implementations, and a discussion on SCALDO properties. Typical efficiencies of 12–5 and 5–1.2 V linear regulators are around 42 and 24%, respectively. When SCALDO prototypes are built, the authors achieve respective end-to-end efficiencies of 79–81 and 58–73%. A loss analysis summary and further developments of the novel technique are also provided, in addition to a discussion to indicate that this is not a variation of the switched capacitor converters.


    1. 1)
      • 1. Schneuwly, A., Gallay, R.: ‘Properties and applications of supercapacitors from the state-of-the-art to future trends’. Proc. of PCIM, 2000.
    2. 2)
      • 2. Reichbach, N., Mellincovsky, M., Peretz, M., et al: ‘Long-term wide-temperature supercapacitor Ragone plot based on manufacturer datasheet’, IEEE Trans. Energy Convers., 2016, 31, (1), pp. 404406.
    3. 3)
      • 3. Barrade, P: ‘Series connection of supercapacitors: comparative study of solutions for the active equalization of the voltages’. Proc. Int. Conf. on Modelling and Simulation of Electric Machines, Converters and Systems, 2002.
    4. 4)
      • 4. Liu, Y., Du, W., Xiao, L., et al: ‘Sizing a hybrid energy storage system for maintaining power balance of an isolated system with high penetration of wind generation’, IEEE Trans. Power Syst., 2016, 31, (4), pp. 32673275.
    5. 5)
      • 5. Hu, A.P., You, Y.W., Chen, F.Y.B., et al: ‘Wireless power supply for ICP devices with hybrid supercapacitor and battery storage’, IEEE J. Emerg. Sel. Topics Power Electron., 2016, 4, (1), pp. 273279.
    6. 6)
      • 6. Barrade, P., Delalay, S., Rufer, A.: ‘Direct connection of supercapacitors to photovoltaic panels with on–off maximum power point tracking’, IEEE Trans. Sustain. Energy, 2012, 3, (2), pp. 283294.
    7. 7)
      • 7. Odeim, F., Roes, J., Heinzel, A.: ‘Power management optimization of a fuel cell/battery/supercapacitor hybrid system for transit bus applications’, IEEE Trans. Veh. Technol., 2016, 65, (7), pp. 57835788.
    8. 8)
      • 8. Pegueroles-Queralt, J., Bianchi, F.D., Gomis-Bellmunt, O.: ‘A power smoothing system based on supercapacitors for renewable distributed generation’, IEEE Trans. Ind. Electron., 2015, 62, (1), pp. 343350.
    9. 9)
      • 9. Yuhimenko, V., Lerman, C., Kuperman, A.: ‘DC active power filter-based hybrid energy source for pulsed power loads’, IEEE J. Emerg. Sel. Topics Power Electron., 2015, 3, (4), pp. 10011010.
    10. 10)
      • 10. Kularatna, N.: ‘Supercapacitors improve the performance of linear power-management circuits: unique new design options when capacitance jump from micro-farads to farads with a low equivalent series resistance’, IEEE Power Electron. Mag., 2016, 3, (1), pp. 4559.
    11. 11)
      • 11. Zhang, L., Song, J.Y., Zou, J.Y., et al: ‘High voltage supercapacitors for energy storage devices applications’. Proc. of Symp. on Electromagnetic Launch Technology, 2008, pp. 14.
    12. 12)
      • 12. Jayalakshmi, M., Balasubramanian, K.: ‘Simple capacitors to supercapacitors – an overview’, Int. J. Electrochem. Sci., 2008, 3, pp. 11961216.
    13. 13)
      • 13. Spillane, D., O’ Sullivan, D., Egan, M.G., et al: ‘Supervisory control of a HV integrated starter-alternator with ultracapacitor support within the 42 V automotive electrical system’. Proc. Applied Power Electronics Conf. and Exposition, 2003, pp. 11111117.
    14. 14)
      • 14. Kularatna, N.: ‘Supercapacitors improve the performance of linear power-management circuits’, IEEE Power Electron. Mag., 2016, 3, (1), pp. 4559.
    15. 15)
      • 15. Gunawardane, K.: ‘Analysis on supercapacitor assisted low dropout regulators’. PhD thesis, The University of Waikato, New Zealand, 2014.
    16. 16)
      • 16. Kularatna, N., Fernando, J.: ‘High current voltage regulator’., US Patent, 9707 430 B2, March 2011.
    17. 17)
      • 17. Kankanamge, K., Kularatna, N.: ‘Supercapacitor assisted LDO (SCALDO) technique- an extra low frequency design approach to high efficiency DC-DC converters and how it compares with the classical switched capacitor converters’. Proc. IEEE Applied Power Electronics Conf., March 2013, pp. 19791984.
    18. 18)
      • 18. Kularatna, N.: ‘Energy storage devices for electronic systems’ (Elsevier, USA, 2014).
    19. 19)
      • 19. Gunawardane, K., Kularatna, N., Steyn-Ross, D.A.: ‘Loss estimation and validation of the SCALDO implementation’. Proc. IEEE 11th Int. Conf. in Power Electronics and Drive Systems, 2015, pp. 8992.
    20. 20)
      • 20. Dispennette, J.: ‘Ultracapacitors bring portability to power’ (Power Electronics Technology Magazine, 2005).
    21. 21)
      • 21. Mars, P.: ‘Coupling a supercapacitor with a small energy harvesting source’. EDN Magazine. Available at, accessed 12 December 2016.
    22. 22)
      • 22. ‘Printed circuit board (PCB) design issues’, Analog Devices. Available at, accessed 31 November 2016.
    23. 23)
      • 23. Kankanamge, K., Kularatna, N., Steyn-Ross, D.A.: ‘Laplace transform-based theoretical foundations and experimental validation-low frequency supercapacitor circulation for efficiency improvements in linear regulators’, IET Power Electron., 2012, 5, (9), pp. 17851792.
    24. 24)
      • 24. Kankanamge, K., Kularatna, N.: ‘Improving the end-to-end efficiency of DC–DC converters based on a supercapacitor assisted low dropout regulator (SCALDO) technique’, IEEE Trans. Ind. Electron., 2013, 61, (1), pp. 223230.
    25. 25)
      • 25. Kankanamge, K., Kularatna, N.: ‘Implementation aspects of a new linear regulator topology based on low frequency supercapacitor circulation’. Proc. IEEE Applied Power Electronics Conf., 2012, pp. 23402344.
    26. 26)
      • 26. Kularatna, N., Fernando, J., Kankanamge, K., et al: ‘A low frequency supercapacitor circulation technique to improve the efficiency of linear regulators based on LDO ICs’. Proc. IEEE Applied Power Electronics Conf., 2011, pp. 11611165.
    27. 27)
      • 27. Kwon, O., Son, J., Kim, T., et al: ‘Implementation of a high efficiency SCALDO regulator using MOSFET’, J. Inst. Korean Electr. Electron. Eng., 2015, 19, (3), pp. 304310.
    28. 28)
      • 28. Kularatna, N., Wickramasinghe, T.: ‘Supercapacitor assisted low dropout regulators (SCALDO) with reduced switches: a new approach to high efficiency VRM designs’. Proc. IEEE Int. Symp. on Industrial Electronics, 2013, pp. 16.
    29. 29)
      • 29. Wickramasinghe, T.: ‘Supercapacitor-based linear converter for voltage regulator modules’. PhD thesis, The University of Waikato, New Zealand, 2016.
    30. 30)
      • 30. Subasinghage, K., Gunawardane, K., Lie, T., et al: ‘Design of an efficiency improved dual-output DC–DC converter utilizing a supercapacitor circulation technique’. Proc. IEEE Sothern Power Electronics Conf., 2016.

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