Design of intrinsically safe buck DC/DC converters

The maximum peak current of inductor of a buck DC-DC converter in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) are analyzed, respectively. It is pointed out that the maximum peak current through the inductor of a CCM buck converter occurs when both the input voltage and the output current reach the highest values. The inner-intrinsic safety of a buck DC-DC converter is determined by comparing the maximum peak current of the inductor with the minimum ignition current. The output short-circuit discharged energy consists of the energy stored in the inductor and the capacitor of a buck DC-DC converter. The Maximum Output Short-circuit Discharged Energy (MOSDE) of the converter within the total operating range is deduced. If the MOSDE is less than the minimum ignition discharged energy, the converter meets the requirement of output intrinsic safety. The design region of inductor and capacitor is obtained according to the requirement of inner-intrinsic safety, output intrinsic safety and the desired output voltage ripple level within the total operating range. By letting the derivative of the MOSDE with respect to inductance to be zero, the optimal values of inductance and capacitance are obtained. Experiment results are in positive to the analysis showing the feasibility of the proposed methods