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This letter presents for the first time experiments combining a previously reported MEMS (microelectromechanical system) electrostatic Vibration Energy Harvester (e-VEH) and the Bennet's doubler circuit. A selflimiting effect on the harvested power, which was not reported before on macroscopic e-VEHs, has been observed. This effect is due to the nonlinear dynamics of the system and to the selfincrease of the electromechanical damping that is typical for eVEHs. With a few volts of initial pre-charge, the Bennet's doubler progressively increases the voltage across the transducer's terminals up to 23 V, where saturation occurs. A power of 2.3 µW is available for a load, when the harvester is excited by 1.5 g at 150 Hz of external acceleration.

Capacitive kinetic energy harvesters (KEH) employ conditioning circuits which achieve a dynamic biasing of the transducer's variable capacitor. This paper, composed of two articles Part 1 and Part 2, proposes a unified theory describing electrical and electromechanical properties of an important and wide class of conditioning circuits: those implementing a rectangular chargevoltage cycle. The article Part 1 introduces a basic configuration of conditioning circuit implementing an ideal rectangular QV cycle, and discusses its known practical implementations: the Roundy charge pump with different flyback mechanisms, and configurations based on the Bennet's doubler. In Part 1, the analysis is done in the electrical domain, without accounting for electromechanical coupling, while in Part 2, the full electromechanical system is analyzed. An optimization approach common to all configurations is proposed. A comparison is made between different topologies and operation modes, based on the maximal energy converted in one cycle under similar electrical and mechanical conditions. The last section discusses practical implementation of circuits with smart and adaptive behavior, and presents experimental results obtained with state-of-the art MEMS capacitive KEH devices.

International audienceThis paper presents a new family of conditioning circuits used in electrostatic kinetic energy harvesters (e-KEHs), generalizing a previously reported conditioning circuit known as the Bennet's doubler. The proposed topology implements a conditioning scheme described by a rectangular charge-voltage cycle (QV-cycle) of tunable aspect ratio. These circuits show an exponential increase of the converted energy over operation time if studied in the sole electrical domain. The QV-cycle's aspect ratio can be set to values that were previously inaccessible with other exponential conditioning circuits. After a brief intuitive presentation of the new topology, its operation is rigorously analyzed and its dynamics are quantitatively derived in the electrical domain. In particular, the aspect ratio of the rectangular QV-cycle describing the biasing scheme of the transducer is expressed as a function of the circuit's parameters. Practical considerations about the use of the reported conditioning circuits in actual e-KEHs are also presented. These include a discussion on the applications of the proposed conditioning, a description of the effects of electrical nonidealities, and a proposition of an energy extracting interface