Dynamic behaviour of hill-climbing MPPT algorithms at low perturbation rates

Hill-climbing algorithms are the most commonly utilized maximum power point tracking (MPPT) control schemes in photovoltaic (PV) applications. Two techniques have been adopted in the literature for implementing such hill-climbing algorithms: reference voltage perturbation where a reference value for the PV generator output voltage is used as the control parameter and direct duty ratio perturbation where the duty ratio of the MPPT converter is used directly as the control parameter. This paper presents a detailed comparison between these two techniques on the basis of system stability. Practical results obtained using a 540Wp PV experimental setup with a resistive load show very good agreement with the theoretical analysis and numerical simulations.