A Modified Hysteresis-Modulation-Based Sliding Mode Control for Improved Performance in Hybrid DC-DC Boost Converter

Sliding-mode (SM) control is a popular nonlinear control strategy for the dc-dc converters as it offers several advantages such as ease of implementation and robust performance against load and line variations. However, the main drawback of the traditional hysteresis-modulation-based SM controller is that its use in the regulation of the dc-dc converters results in a tradeoff between the overshoot and speed of the closed-loop output voltage response. This is due to the use of the traditional proportional-integral (PI) controller which is used to generate the reference inductor current of the controller. To overcome this problem, the traditional PI-based SM controller is modified such that the reference inductor current used in the sliding surface is now generated using an integral whose integrand is a function of the normalized output voltage error of the converter. A key feature of the integrand is that it is bounded by a user-defined constant. The modified SM control strategy is applied to a hybrid dc-dc boost converter. The expression of the equivalent control signal of the proposed SM controller is derived and the detailed stability analysis of the closed-loop controlled system is given. Also, experimental results are provided to show that the proposed SM controller gives an improved performance as compared to that obtained using the existing PI-based SM controller.