Three-level quadratic boost DC-DC converter associated to a SRM drive for water pumping photovoltaic powered systems

Abstract This paper presents a water pumping system powered by solar photovoltaic (PV) panels employing a switched reluctance motor (SRM) drive and a three-level quadratic Boost (3LQB) DC-DC converter for a dual output. The DC-DC topology is characterized by quadratic voltage static gain, capability to ensure voltage balance in the output capacitors and reduced voltage stress across power switches and diodes. The three-level voltage of the DC-DC converter allows to connect an asymmetrical half-bridge (AHB) converter integrated into the SRM drive. The DC-DC converter also operates in continuous conduction mode (CCM) which, combined with a proposed maximum power point tracking (MPPT) algorithm, helps to optimize the power supplied by the PV panels. A laboratory prototype was also developed and installed in a workbench to verify its practical implementation considering all devices involved. The tests were performed considering different loads and solar irradiations to verify the system performance under different situations. The PV panels were simulated using a remotely controlled DC power source to impose the typical characteristic I-V curves of the PV panels according to solar irradiation and the water pump behavior was emulated in the laboratory using a controlled torque load coupled to the SRM drive. The experimental results indicate that the proposed solution allows to fully exploit the solar energy to provide as much as possible a continuous water flow in isolated pumping solutions. The operating limits of this solution should be determined by the minimum water flow rate required, necessary head (elevation) and net positive suction head (NPSH).