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A Coil Connection Switching Strategy for Maximum Power Delivery in Electromagnetic Vibration Energy Harvesting System

Maximum Power Point Tracking (MPPT) approaches have been widely applied in energy harvesting systems. However, such control algorithms such as Perturb-and Observe (P&O) method usually require DSP or customized control ICs. This leads to high power consumption and high cost. This paper proposes a novel strategy to realize max. power delivery through coil connection switch approach where the input impedances and voltage/current levels are adjusted according to different output voltages. A single stage AC-DC dual boost converter is employed with fixed duty cycle to charge a super-capacitor load to verify the concept. Three sets of harvester coils are used and are connected in either parallel or series. The switch of coil connections is realized through isolated analog switches. It is demonstrated that the harvester with dual boost converter under proposed strategy achieves an maximum output power of 3.628 mW in 0.2 g acceleration, which is 41.7% higher than same converter without coil connection switching. With proposed method, the output power reaches to 98.7% of the output power with traditional P&O MPPT strategy. It also achieves higher efficiency and more compact system size than traditional P&O MPPT.