A Single-Switch DC-DC Converter for Bipolar DC Microgrids

DC microgrids have begun to play a significant role within the broader landscape of electric distribution systems. Within this context, a novel non-isolated DC-DC buck-boost converter is introduced in this project. The topology is developed for unipolar or bipolar DC microgrids. In the case of the topology that is specially adapted for the bipolar DC microgrid, although the converter uses only one switch, its output currents depend on the voltage level of the bipolar DC microgrid. This project presents the design and implementation of a single switch non-isolated buck-boost converter controlled by an Arduino Uno for DC microgrid applications. The converter is capable of stepping up or stepping down a 12V input voltage to a variable output voltage ranging from 0V to 40V based on user-adjusted PWM duty cycle. The system employs a potentiometer for manual duty cycle control, an I2C LCD for real-time monitoring of PWM values, duty cycle percentage, output voltage, and operating mode (BUCK or BOOST). A voltage divider network using 100kΩ and 15kΩ resistors scales the output voltage to a safe level for Arduino analog input. The IRFZ44N MOSFET serves as the switching element, while inductors and filter capacitors ensure smooth DC output. Its key characteristics include a simplified topological structure, reduced voltage stress on the switch, and continuous input current. These are all enabled by the use of a single switch.  The developed system demonstrates effective voltage regulation with visual feedback, making it suitable for low-power DC microgrid applications such as battery charging, LED lighting, and renewable energy integration. Experimental results show successful buck and boost operation with stable output voltage across varying duty cycles, with automatic mode detection providing intuitive user feedback.