Large-signal feedback control of a bidirectional coupled-inductor Cuk converter

Under conditions of order reduction, a nonlinear control of a bidirectional coupled-inductor Cuk converter suitable for large-signal applications is presented. The converter is accurately modeled as a second-order bilinear system and the conditions established for local controllability. The integration of converter state equations and the subsequent introduction of a linear recurrence between the output variable and an external reference signal lead to a nonlinear control law that is implemented by means of an analog divider, standard operational amplifiers, and a pulse-width modulator. As a result, the output variable follows proportionally the reference signal, this allowing the obtention of different types of power waveforms in the converter output. Experimental results verify the theoretical predictions.