Control Techniques for DC-DC Buck Converter with Improved Performance

Abstract

The switched-mode dc-dc converters are some of the most widely used power electronics circuits for its high conversion efficiency and flexible output voltage. These converters used for electronic devices are designed to regulate the output voltage against the changes of the input voltage and load current. This leads to the requirement of more advanced control methods to meet the real demand. Many control methods are developed for the control of dc-dc converters. To obtain a control method that has the best performances under any conditions is always in demand. Conventionally, the dc-dc converters have been controlled by linear voltage mode and current mode control methods. These controllers offer advantages such as fixed switching frequencies and zero steady-state error and gives a better small-signal performance at the designed operating point. But under large parameter and load variation, their performance degrades. Sliding mode (SM) control techniques are well suited to dc-dc converters as they are inherently variable structure systems. These controllers are robust concerning converter parameter variations, load and line disturbances. SM controlled converters generally suffer from switching frequency variation when the input voltage and output load are varied. This complicates the design of the input and output filters. The main objective of this research work is to study different control methods implemented in dc-dc converter namely (linear controllers, hysteresis control, current programmed control, and sliding mode (SM) control). A comparison of the effects of the PWM controllers and the SM control on the dc-dc buck converter response in steady state, under line variations, load variations is performed.