The fast response, high efficiency, and good reliability are very important characteristics to electric vehicles (EVs) dc/dc converters. Two-stage dc-dc converter is a kind of dc-dc topologies that can offer those characteristics to EVs. Presently, nonlinear control is an active area of research in the field of the control algorithm of dc-dc converters. However, very few papers research on two-stage converter for EVs. In this paper, a fixed switching frequency sliding mode (FSFSM) controller and double-integral sliding mode (DISM) controller for two-stage dc-dc converter are proposed. And a conventional linear control (lag) is chosen as the comparison. The performances of the proposed FSFSM controller are compared with those obtained by the lag controller. In consequence, the satisfactory simulation and experiment results show that the FSFSM controller is capable of offering good large-signal operations with fast dynamical responses to the converter. At last, some other simulation results are presented to prove that the DISM controller is a promising method for the converter to eliminate the steady-state error. 1. Introduction Depleting fossil fuel supply and increasing regulations on greenhouse continue to pressure the automotive industry to transition toward more sustainable energy sources [1]. Due to numerous advantages in energy conservation and environmental protection, electrified vehicles which include battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs) have been actively studied and developed and are widely viewed as an important transition towards sustainable transportation [1–3]. The development of EVs power electronics system control, composed of dc-ac inverters and dc-dc converters, appeals to large numbers of researchers in the modern industry. A dc-ac inverter supplies the high power electric vehicle motors torques of the propulsion system and utility loads, whereas a dc-dc converter supplies conventional low-power and low-voltage loads [4]. As an important component of EVs, dc-dc converter is added to make the power battery and inverter work harmoniously. Although a lot of methods are used to provide monitoring, diagnosis, and control functions to enhance the operations of battery packs [1–3, 5, 6], it is necessary to study the dc-dc converter to ensure its stability and reliability. Two-stage dc-dc converter topologies have recently begun to receive interest in high input voltage, low voltage/high current output dc-dc conversion [7–10]. Generally, the two-stage topologies
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