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Piezoelectric energy harvester (PEH) arrays are practical solutions to the low and unreliable power output of a single PEH. However, most PEH circuits are developed for addressing the one-channel ac input from a single PEH. In this article, an extensible rectifier-less synchronized switch harvesting on inductor (ReL-SSHI) array interface with the maximal power point tracking (MPPT) function to manage the multiple ac inputs from the PEH arrays is designed. The ac–dc conversion is performed by the ReL-SSHI topology with passive peak switches featured with self-powered characteristic and fast cold-start. Only one shared inductor is employed, greatly reducing the circuit volume and cost. The MPPT module for each channel is implemented by a simple envelope detector and an ultra-low power hysteresis controller and achieves continuous energy extraction by adapting the fractional normal-operation voltage method. A developed discrete array interface able to handle three PEHs effectively executes the MPPT for each channel with the uphill and downhill response speeds of 2.0 and 7.1 V/s, and a maximal MPPT efficiency of 97.1%. This circuit boosts the power output by 485% compared with that by the traditional full-bridge rectifier, around 33% higher than that from existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvester (PEH) arrays are promising in many application scenarios. However, few interface circuits have been developed to manage the multiple ac inputs from PEHs. This article proposes an extensible parallel synchronized switch harvesting on inductor array interface scheme to realize a multiinput conversion from PEH arrays. We develop a split-inductor-capacitor topology that can extract electrical energy from multiple PEHs. The proposed circuit topology effectively handles the inductor access conflict in the cases of PEHs with close, identical, and opposite vibration phases, insensitive to ac input phase changes. For demonstrating the capability of dealing with multiple ac inputs from PEHs and the enhancement effect on power output, we construct and test a self-powered three-channel array circuit with the passive peak detection function. Excited by sinusoidal vibrations, our circuit effectively avoids the energy return and efficiently achieves the power combination of the three PEHs. Compared with the classic full-bridge circuit, the proposed circuit helps increase the power output by 4.8 times. Also, to show the universality of the circuit, the circuit's operation under various excitations istested and analyzed. [ABSTRACT FROM AUTHOR]

A novel hybrid control strategy combining vector control and current continuous conduction is proposed in this paper to improve the performance of a hybrid-excitation switched reluctance motor (HESRM). Vector control, widely used in ac machines, is redefined in HESRM based on static torque characteristic to simplify an HESRM controller and reduce torque ripple. However, at a high-speed and heavy-load operation, current tracking accuracy deteriorates and torque ripple reduction effect gets worse. Current continuous conduction is combined with vector control to improve current tracking accuracy and maintain smooth torque ripple. In the HESRM, the power generally falls nearly in proportion to the square of speed over based speed, and a traditional control technique can maintain only a narrow constant power range. This novel vector control is easy to achieve phase advance and current continuous conduction simultaneously. By combining these two together, the HESRM can extend the constant power in a wider speed range and efficiency is also improved. Simulations and experiments in different conditions are carried out to verify the effectiveness of a hybrid control strategy. [ABSTRACT FROM AUTHOR]