Current Sensor-Free Output-Feedback Voltage Control for DC/DC Converters via Critical Damping Injection Technique for Converter-Fed Servo System Applications

This study proposes an observer-based multiloop output-feedback system that regulates the output dc-link voltage of dc/dc converters to the desired value to lower the system model dependence level. There are a few features: 1) the outer loop injecting the nonlinear active damping to ensure the critically damped output voltage response; 2) a model-independent output voltage derivative observer facilitates the inner loop and eliminates the need for complex matrix calculations for tuning the estimation performance; and 3) the use of a pole-zero cancellation acceleration error stabilizer for the inner loop helps maintain the targeted closed-loop performance. The experimental study adopts a 420-W brushless dc motor dynamo system as the load for the prototype 600-W bidirectional converter controlled using the proposed solution.