Control Models of Switch Mode Maximum Power Point Tracking Interfaces for Energy Harvesting Devices

In this paper, we present a method to model and control the interface electronics in order to obtain maximum power transfer from a rotational energy harvester. A state-space representation of a boost converter (with component parasitics) was derived and embedded in a control loop that performs input impedance matching to the armature resistance of the rotational harvester. Root locus techniques were used to choose the proportional-integral (PI) controller gain. A comparison of simulation results from Matlab and PSpice are presented. The methods reported in this paper are valid for other types of harvesters and interface electronics by changing the modelling parameters. It was found that increasing the controller gains results in a more damped closed-loop system response and for this specific example, the closed-loop behaviour is non-oscillatory for all positive values of gain.