Staying alive under intermittent power

Today's low-power electronic systems cannot cope with a highly variable supply of power. For example, if they are powered by an energy harvester in an environment where the available power is low and sporadic, the system dies once the energy storage becomes depleted or damaged. Electronics requires a relatively high surge current to flow at start-up, and therefore even when the power returns, some systems will not start up again.

With an increasing number of applications of microelectronic systems calling for remote, embedded and miniaturized solutions, we have been funded by EPSRC to investigate power and energy management techniques for the design of robust and reliable electronics, in particular for situations where there is a variable, unreliable source of energy.

A number of situations, or states, have been defined, according to the level of depletion of on-board energy storage, and to how variable the power supply is. The most challenging states, for example where the input power is sporadic and spread over a wide range from nW to mW, are outside of the survival zone of modern electronics. We aim to extend this survival zone.

Techniques that we use include control circuits that are able to ride through variable voltages, the detection of states, and reconfigurable hardware resources and control algorithms to suit sporadic and sub-microwatt input power. The chief aim of this project is to produce survival zone design methods for the microelectronics design community.

Acceleration measured on Bristol's suspension bridge, showing the motion of the bridge due to traffic. This vibration, as a source of ambient power, exhibits high variability. Power management for variable low-power sources is the focus of this project.
Two examples of reconfigurable hardware resources: asynchronous Intel 8051 microprocessor (left) and fully self-timed SRAM (right). They allow robust operation under unstable and non-deterministically variable supply voltages and various operating conditions.

Staying alive in variable and intermittent energy environments (SAVVIE)

Bristol researchers

  • Guang Yang: Low power, analogue microelectronic design
  • Bernard Stark (Lead-PI): Power electronics and devices, micro-renewables
  • Steve Burrow: Kinetic energy harvesters and power management
  • Simon Hollis: Low power micro-electronic design

Newcastle researchers

Project partners

Texas Instruments

Project publications

  • G. Yang, B. H. Stark, S. J. Hollis and S. G. Burrow, Optimization of Passive Voltage Multipliers for Fast Start-up and Multi-voltage Power Supplies in Electromagnetic Energy Harvesting Systems, PowerMEMS 2014.
  • Challenges for Energy Harvesting Systems under Intermittent Excitation, IEEE Journal on Emerging and Selected Topics in Circuits and Systems (JETCAS), 2014.
  • Asynchronous design for new on-chip wide dynamic range power electronics, Design, Automation and Test in Europe Conference and Exhibition (DATE), 2014. 
  • Energy Efficiency of Micropipelines Under Wide Dynamic Supply Voltages, IEEE Faible Tension Faible Consommation (FTFC), 2014.
  • Asynchronously Assisted FPGA Architecture for Variability, 24th International Conference on Field Programmable Logic and Applications, 2014.
  • Variability analysis of self-timed SRAM robustness, 23rd International Workshop on Power And Timing Modeling, Optimization and Simulation, 2013. 
  • Resistive Matching with a Feed-Forward Controlled Non-Synchronous Boost Rectifier for Electromagnetic Energy Harvesting, Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2013.
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