Electrolytic Capacitor-less Isolated Resonant Converter-fed BLDC Drive for Solar Water Pumping Application

The electrolytes used in electrolytic capacitors (ECs) dries out with time due to heating, voltage stress and humidity leading to the degradation of the ECs. To address this concern, this paper presents a DC link electrolytic capacitor-less (ECL) isolated resonant converter-fed brushless DC motor drive for solar water pumping applications. For DC-DC converter operation, an isolated LLC-based dual half-active bridge resonant converter is used. The resonance in the isolated DC-DC converter (IDC) provides soft-switching operation to reduce the switching losses at high-frequency and isolation restricts the flow of the leakage current caused due to the capacitive path formed between the panels and the ground. For the analysis of the IDC, fundamental harmonics approximation has been used. The output film capacitor of the secondary half-active bridge is used as a DC-link capacitor. A three-phase voltage source inverter has been utilized for the electronic commutation of the BLDC motor. A 120° conduction scheme with the H-PWM-L-ON method has been adapted for the smooth operation of the BLDC motor. A 500 W laboratory prototype of the proposed drive system has been built and tested for the steady-state operation.