Design and analysis of energy recyclable bidirectional converter with digital controller for multichannel microstimulators
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The power supply modulated microstimulator system can drive an expandable electrode array with reduced heat generation across the current drivers and high stimulation efficiency. Here, we present a comprehensive analytical modelling of the system to investigate internal and external energy flow during biphasic stimulation pulses spanning over varying loading configurations (e.g. number of electrodes, and stimulation current amplitude) that were not covered by existing works on the power supply modulated microstimulators. This paper fills the research gap by presenting the systematic tools for attaining insights of a stimulator system featuring a bidirectional DC–DC converter with an algorithmic digital controller. The models employed here are based on traditional analytical methods such as transfer functions and state-space dynamic models incorporating various circuit elements incurring power loss. With the models, the behaviour and power efficiency under a wide range of parameters associated with stimulator are attained. Numerical assessment reveals that the digital controller can track the output supply voltage at the phase transition boundaries just in tens of switching cycles. The system was also studied on a verification platform, where the internal signals of the digital controller were carefully examined. Measurement results show that the system behavior well matched to the simulation results, demonstrating the effectiveness of the analytical system model for obtaining key insights for generic large-scale micro-stimulator designs.
KeywordsElectrical stimulator Power supply modulation Energy recycling DC–DC converter
This work was supported in part by the RGC research Grant Reference: 610412, the NRPP grant from Qatar National Research Fund Reference: NPRP9-421-2-170 and the Research Committee of the University of Macau (MYRG2015-AMSV-00140).
- 5.Lee, K.F.E. (2010). A timing controlled ac-dc converter for biomedical implants. In ISSCC Dig. Tech. Papers, Feb. 2010, pp. 128–129. doi: 10.1109/ISSCC.2010.5434021.
- 9.Park, S. Y., Cho, J., Lee, K., & Yoon, E. (2015). A pwm buck converter with load-adaptive power transistor scaling scheme using analog-digital hybrid control for high energy efficiency in implantable biomedical systems. IEEE Transactions on Biomedical Circuits and Systems, 9(6), 885–895. doi: 10.1109/TBCAS.2015.2501304.Google Scholar
- 11.Luo, P., Luo, L., Li, Z., Yang, J., & Chen, G. (2002). Skip cycle modulation in switching dc-dc converter. In IEEE International Conference on Communications, Circuits and Systems and West Sino Expositions, 2002 (Vol. 2, pp. 1716–1719).Google Scholar
- 18.Streetman, B. G., & Banerjee, S. (1995). Solid state electronic devices (Vol. 2). Englewood Cliffs: Prentice-Hall.Google Scholar
- 19.Eichhorn, T. (2005). Estimate inductor losses easily in power supply designs. Power Electronics Technology, 31, 14–24.Google Scholar
- 20.Venkatachalam, K., Sullivan, C. R., Abdallah, T., & Tacca, H. (2002). Accurate prediction of ferrite core loss with nonsinusoidal waveforms using only steinmetz parameters. In IEEE Workshop on Computers in Power Electronics (pp. 36–41).Google Scholar
- 23.Lee, Y. H., Huang, S. C., Wang, S. W., Wu, W. C., Huang, P. C., Ho, H. H., et al. (2012). Power-tracking embedded buck-boost converter with fast dynamic voltage scaling for the soc system. IEEE Transactions on Power Electronics, 27(3), 1271–1282. doi: 10.1109/TPEL.2010.2101085.CrossRefGoogle Scholar