This paper proposed a PV application based on a prototype of four switch buck-boost (FSBB), Because this application usually faced with the function that the step-up mode and step-down mode are both needed in the Maximum power point tracking control for a better efficiency and power density, especially in PV-UAV power system where the weight and volume are the key parameters. So, in order to reduce the inductor weight and improve the efficiency at the maximum power point of the photovoltaic module, usually the zero-voltage switch (ZVS) on control schemes with high switching frequency is a good choice to reduce the loss of the GaN device. After reviewing many proposed control methods, a control strategy with quadrilateral inductor current is suitable for this application. Based on a simplified real-time control algorithm, a MPPT control scheme that reduced the RMS of the inductor current and realizing the ZVS operation under 100V-200V input and output voltage was proposed. And the whole control is realized in a simple calculation. Finally, a 400W MPPT converter is built to test the proposed MPPT control scheme, and the controller is a cheap DSP usually used in power converter. and the prototype reaches 4W/g power density and 98.3% peak efficiency