A smooth sliding mode control for a high-conversion-ratio bidirectional DC-DC converter

With the development of renewable power generation technologies, bidirectional DC-DC converters (BDC) are being widely used in electric vehicles, micro-grid, and hybrid power system. This paper presents a floating interleaved Buck- Boost BDC (FIB-BDC), with high conversion ratio, low current ripple and low stress. Then the principle of the FIB-BDC is analyzed and the state model is built. On the other hand, the DC bus voltage is seriously disturbed by the intermittent input of renewable energy, the random disturbance of the load, and power flow switching. Therefore, a smooth robust control is designed in this paper, which is based on the hyperbolic tangent function tanh(x) with the Super-Twisting (ST) high order sliding mode control (HOSMC), so called TST-SMC or TST. It is smoother than traditional HOSMC without losing robustness and rapidity. Moreover, a dual-loop control scheme is designed for the FIB-BDC, with outer voltage loop and inner current loop. Finally, simulation experiments are tested by stepping disturbance of the load, and switching the power flow under PI, ST and TST controller. And the experimental results verified the effective of the proposed controller and the topology.