Abstract
This study presents a synthesis of a new energy harvest system that consists of a hula-hoop transformer, a micro-generator and an interface energy harvest circuit. The hula-hoop transformer mainly comprises a main mass sprung in one translational direction and a free-moving mass attached at one end of a rod, the other end of which is hinged onto the main mass. The transformer is capable of transforming linear reciprocating motions to rotary ones based on the concepts similar to the hula hoop motions. The transformer is subsequently integrated with a miniaturized rotary generator in size of 10 × 10 × 2 mm3 and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multi-polar hard magnet ring made of NdFeB. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The optimized generator offers 4.5 volt and 7.23 mW in rms at 10,000 rpm. With micro-generator successfully fabricated, a novel energy harvest circuit employing a new dual phase charge pump, power management circuit, a low dropout regulator and battery charger is designed and fabricated via the 0.35 μm process. This charge pump circuit owns the merit of automatic conversion of low-power AC signals by the micro-generator to DC ones. Experiments were conducted to show the favorable performance of the proposed energy harvest system. This is the first work that invents a motion transformer from ubiquitous reciprocating to rotational motions. In this way, higher-efficient energy conversion via compact-sized rotational electromagnetic generators can be realized as opposed to popular piezoelectric structures.
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Acknowledgments
The authors appreciate the support from National Science Council of R.O.C under the grant no. NSC 97-2221-E-007-050, and are grateful to the National Center of High-performance Computing for providing excellent computation capacity and National Chip Implementation Center (CIC) of Taiwan for implementing the energy harvest circuit. This work was supported in part by the UST-UCSD International Center of Excellence in Advanced Bioengineering sponsored by the Taiwan National Science Council I-RiCE Program under grant no: NSC-99-2911-I-010-101.
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Chao, P.CP., Shao, C.I., Lu, C.X. et al. A new energy harvest system with a hula-hoop transformer, micro-generator and interface energy-harvesting circuit. Microsyst Technol 17, 1025–1036 (2011). https://doi.org/10.1007/s00542-011-1276-0
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DOI: https://doi.org/10.1007/s00542-011-1276-0