Small-Signal Modelling and Design Validation of PV-Controllers With INC-MPPT Using CHIL

The maximum energy that can be harvested from a photovoltaic (PV) system at any instant depends on the effectiveness and response time of the maximum power point tracking (MPPT) algorithm used and related controllers. To facilitate proper controller design, a precise mathematical model of the system is required. This paper presents a comprehensive small signal model capable of describing the dynamics of the power stage and controllers. The power stage consists of a PV system and a dc-dc boost converter including the parasitic elements operating in inverse-buck mode. The MPPT and PV voltage controller constitute the control system. The steady state and transient responses of the system are evaluated by controller-hardware-in-the-loop approach where the power stage is simulated in a real time digital simulator and the control operations are performed in a digital signal processor. The frequency response is experimentally determined using a Gain-Phase analyzer. This unique approach allows control system designers to test and validate a control system design before implementing it with a laboratory scale hardware or any real-life application. This method adds an extra layer of design authentication on top of conventional offline simulations.