摘要：The inductance and capacitance used in the switching power supply system could provide a huge instantaneous spark energy when the inductor disconnected and the capacitor shorted, which leads to the safety problem in the explosive environment. This paper proposes an intrinsically safe Buck converter with LC low-pass filter to reduce the required inductance and capacitance for the desired electrical and intrinsically safe performance. The energy transmission processes of the proposed converter are analyzed deeply, and it is pointed out that its operating mode can be divided into three types, Continuous Conduction Mode (CCM), Unidirectional Discontinuous Conduction Mode (UDCM) and Bidirectional DCM (BDCM). The critical inductance among the three modes is deduced. The analytic expression of the Output Voltage Ripple (OVR) in each operating mode is obtained. The variation relation between the OVR and the inductance is analyzed. Then the maximum value of OVR (MOVR) is obtained. Moreover, it is pointed out that the OVR reaches the maximum when input voltage is the maximum and the load resistance is the minimum in CCM. For a given electrical performance specification, comparing the required inductance and capacitance of the proposed converter with that of the typical Buck converter, it obtained that the proposed converter needs a lot less capacitance and inductance. The experiment results verify the correctness of the theory analysis and the feasibility of the design method.
