Maximum power point tracking method based on impedance matching for a micro hydropower generator.

• The optimum operation point is tracked by matching the virtual load impedance. • No microcontroller is used in the MPPT circuit. • The MPPT method can handle the intermittent and fast-changing voltage. • The energy efficiency of the generator was improved by 0.8 to 1.7 times. • The larger temporal storage capacitor helps to improve the energy efficiency. An innovative maximum power point tracking method based on impedance matching is proposed and applied in a micro hydropower generator. The micro hydropower generator exploits the water head which is derived from the repeated diving of the marine animal to power the marine telemetry tag. The output voltage of the micro generator is intermittent and changes very fast. The present maximum power point tracking methods can't deal with this type of intermittent and fast changing voltage of the generator. Hence, to track the optimum operation point and improve the energy efficiency, a new MPPT method which tracks the optimum operation point by directly matching the virtual load impedance of the generator to its internal resistance is proposed. The impedance matching law is developed based on the mathematical model. The experiment of the MPPT hardware is conducted, and the experiment result is used to validate the simulation model. Based on the validated model, the analysis results show that under the fluid pressure from 2 MPa to 8 MPa, the energy efficiency of the generator that uses the MPPT method increase to 1.8 to 2.7 times the one with the direct charging method. The results indicates the effectiveness and advantage of the MPPT method in tracking the optimum operation point and improving the energy efficiency in the context of intermittent and fast changing voltage. [ABSTRACT FROM AUTHOR]