An Improved PID Controller Using Fuzzy Logic for SEPIC DC/DC Converter

The SEPIC converter is one of the unique DC-DC converters where this converter can maintain a constant output under varying and changing input conditions, a small input current ripple, and the same output polarity with its input, therefore this converter is widely used in systems with input voltages that vary from nominal voltage such as battery-based systems, and renewable energy-based generation fields such as photovoltaic. However, the characteristics of the output response in the open loop condition of the SEPIC converter have a considerable overshoot, the time to reach a steady state condition is quite long, and oscillations occur at the output voltage. Then, with changes in input voltage and load it will greatly affect the output response of the SEPIC converter. Therefore, fuzzy logics are employed in order to adjust the output voltage in the SEPIC converter when there are changes in input voltages and various loads. Based on the test results, the fuzzy logic on PID controller has a better output response than the PID controller, because the output of SEPIC converter uses proposed controller, has a slight voltage deviation and recovery time than the PID controller.