A nonlinear control approach for a bi-directional full-bridge AC/DC converter

This paper presents a nonlinear controller based on the Control Lyapunov Function theory for grid-connected bidirectional AC/DC converters. Conventionally, the AC/DC converters are controlled with linear controllers (typically PI or PID controllers) and this usually does not lead to an optimally controlled system for a wide load range due to the nonlinearity of the converter. The proposed nonlinear controller, based on the Control-Lyapunov Function (CLF) theory, is able to shape the input current as well as regulate the DC-bus voltage. The controller is able to achieve a superior performance compared to typical linear regulators and maintain reliable and stable operation for a wide range of operation. The performance of the controller is verified experimentally with an FPGA-controlled full-bridge converter and is shown to have superior dynamic response compared to a typical linear regulator.