A sliding mode observer for the load resistance estimation in a boost converter

In this paper the control of a boost converter in the presence of an uncertain load resistance is addressed. Exploiting a suitable change of coordinates and pointing out the internal and the external dynamics of the converter, a sliding mode control law is considered for the regulation of the converter output voltage. A sliding mode observer is introduced, whose dynamics allows to estimate the unknown load resistance. The robust control algorithm is designed to actuate directly the switching device, thus eliminating the need for a waveform modulator. The overall control system has been tested in simulated scenario. The performances are evaluated comparing with a standard double loop control scheme for boost converter, with a linear controller in the external loop and a sliding mode controller in the internal loop. Simulation tests show the effectiveness of the proposed approach, which is superior to the standard controller.