Abstract
This paper reports on an electrostatic Vibration Energy Harvester (e-VEH) system, for which the energy conversion process is initiated with a low bias voltage and is compatible with wideband stochastic external vibrations. The system employs the auto-synchronous conditioning circuit topology with the use of a novel dedicated integrated low-power high-voltage switch that is needed to connect the charge pump and flyback – two main parts of the used conditioning circuit. The proposed switch is designed and implemented in AMS035HV CMOS technology. Thanks to the proposed switch device, which is driven with a low-voltage ground-referenced logic, the e-VEH system may operate within a large voltage range, from a pre-charge low voltage up to several tens volts. With such a high-voltage e-VEH operation, it is possible to obtain a strong mechanical coupling and a high rate of vibration energy conversion. The used transducer/resonator device is fabricated with a batch-processed MEMS technology. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110–170 Hz, up to 0.75 μW of net electrical power has been harvested with our system. This work presents an important milestone in the challenge of designing a fully integrated smart conditioning interface for the capacitive e-VEHs.
Highlights
The kinetic vibrations present in many environments are potential sources for the supply of autonomous microsystems
This paper presents the first integrated on silicon high-side switch Sw commuting high voltage between the charge pump and the flyback in the conditioning circuit of Fig. 1a
That is because the full potential of electrostatic transducers for energy conversion may only be explored with high-voltage operation
Summary
The kinetic vibrations present in many environments are potential sources for the supply of autonomous microsystems. High bias voltage is necessary to achieve strong mechanical coupling with an electrostatic transducer This fact, combined with ultra low power requirement for the control circuitry, makes the design of the conditioning circuit very challenging. A significant advantage of this circuit over charge-constant [1] or voltage-constant [2] architectures is its suitability for operation with a resonator excited by broadband stochastic vibrations. To comply with the speed and power consumption requirements, we designed a novel ultra-low power level shifter with zero static power consumption This driver can be used to implement a smart control algorithm so to adapt the conditioning circuit operation to different application contexts [5]. That is because the full potential of electrostatic transducers for energy conversion may only be explored with high-voltage operation
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