Analysis of DC-DC Conversion for Energy Harvesting Systems Using a Mixed-Signal Sliding-Mode Controller

Increasing efficiencies in electronic devices have opened the door for energy harvesters to power wireless systems by scavenging energy from solar, thermal, or mechanical sources. The design of an efficient power supply that can regulate scavenged energy to produce stable voltages for multiple loads is presented here. To limit energy dissipation and increase the flexibility of the regulator, a discrete-time sliding-mode controller is presented. The performance of sliding-mode controllers is hard to predict because their switching frequency and output voltage ripple are dependent on duty cycle and load conditions. An analytical approach for the closed-loop steady- state behavior of a discrete-time sliding-mode controller is presented here. The proposed analytical solution matches measured results to within 4% for duty cycles ranging between 0.1 and 0.9.