Small Wind Turbine Sensorless MPPT: Robustness Analysis and Lossless Approach

The configuration permanent-magnet synchronous generator with a diode bridge is frequently used in small wind energy conversion systems due to its reliability and low cost. In order to perform a sensorless maximum power point tracking, a suitable method consists of imposing the relationship between the dc current and the dc voltage in optimum operation. However, this strategy requires having knowledge of the system parameters, which are inaccurately known and can vary in real applications. Thus, the optimum curve is not precisely obtained, leading to power losses. This paper evaluates to what extent the power is reduced due to parameter errors. It is shown how the power can be drastically decreased due to some parameter variation, whereas it is not affected by others such as the resistance, which can then be neglected in order to simplify the model. Simulation results for an actual wind profile validate the theoretical analysis.