<p>This paper proposes a robust voltage controller designed for a high voltage gain floating interleaved DC-DC boost converter (FIBC), specifically for the fuel cell applications. The proposed dual loop cascade controller is utilizing a nonsingular terminal sliding mode control algorithm for voltage control in the outer loop and super twisting sliding mode control algorithm for current control in the inner loop. The outer loop generates a reference current for the inner control loop based on the difference between the desired and actual output voltages. while the inner loop, which has a continuous control signal and the sliding surface is defined for the inductor current to address converter uncertainties. The stability of the proposed controller is proven using the Lyapunov stability theorem. Moreover, the effectiveness and robustness of the proposed controller against the converter parameters uncertainties, input voltage variations and external disturbances is analyzed in dept, and validated by the simulation results. The simulation results shows that the proposed controller maintains a stable output voltage without any voltage overshoots, even in the presence of converter parameter uncertainties and external disturbances.</p>