应用于易燃易爆环境的直流电源必须满足防爆要求，本质安全是最佳的防爆形式，本质安全开关电源必将获得广泛应用。开关变换器是组成开关电源的核心基础，因此，对本质安全开关变换器的基础理论及关键技术进行研究具有重要理论意义和实用价值。 提出了一种输出电流可控的大功率安全栅电路，设计了一种快速的截止型输出短路保护电路。针对Boost变换器实现本质安全存在的问题，提出了一种本质安全型Boost变换器的改进电路。为进一步提高本质安全开关变换器的输出功率，发明了一种输出电容短路火花能量释放电路。通过大量实验验证了提出的一系列新电路的可行性。 发现了Boost和Buck-Boost变换器存在完全电感供能模式(CISM)、不完全电感供能且连续导电模式(IISM-CCM)及不完全电感供能且不连续导电模式(IISM-DCM) 三种工作模式，并推导得出了其临界条件和变换器在整个动态工作范围内的最大输出纹波电压。指出对于Boost和Buck-Boost变换器，最小负载电阻和最低输入电压所对应的CISM和IISM的临界电感，即为使得最大输出纹波电压极小的最小电感，且最大输出纹波电压的极小值与电感无关。 推导得出了开关变换器在整个工作范围内的最大输出短路释放能量，指出其不仅与输出电压和电容有关，而且与开关频率和电感及其电流有关。发现了输出短路火花与负载电阻密切相关的现象。指出不能直接套用简单电容电路的引燃曲线作为开关变换器的输出本质安全判据。为此提出了一种将开关变换器输出短路放电特性转化为等效简单电容电路的方法，并据此首次提出了开关变换器输出本质安全的非爆炸判断方法。通过大量火花实验验证了提出方法的可行性。 推导得出了开关变换器在整个工作范围内的最大电感电流。发现了流过开关变换器的电感电流远小于该电感对应的引燃电流时也会引燃爆炸性气体，并且电感分断火花的引燃能力与输出电容有关的现象，指出直接套用简单电感电路的引燃曲线作为开关变换器的内部本质安全判据是不严格的。为此，在深入研究开关变换器的电感分断放电火花的基础上，提出了一种将开关变换器的电感分断放电特性转化为等效简单电感电路的等效电阻分析法，并据此首次提出了开关变换器内部本质安全的非爆炸判断方法。通过大量火花实验验证了提出方法的可行性。 建议了一种本质安全开关变换器的设计方法。推导得出了满足性能指标要求、输出本质安全要求和内部本质安全要求的电感和电容参数的取值范围，深入探讨了开关频率对元器件参数取值范围的影响，并分别得出了输出本安型开关变换器和完全本质安全型开关变换器的最小开关频率。

Direct current power supplies applied in the flammable and explosive conditions must meet the requirements of anti-explosive. As the optimal means, intrinsically safe switching power supplies will be of promise in the future. Thus, it is nessecery to investigate the basic theory and key techniques of intrinsically safe switching converters. A new large-power safe-barrier with controlled output current is proposed. A fast protection circuit is designed to cut off the source power when the output short-circuit occurs. To overcome the difficulty of Boost converters to realize intrinsic safety, an improved structure of Boost converter is presented. A novel capacitor short citcuit spark energy releasing circuit is invented to further improve the output power of intrinsically safe switching converters. It is pointed out that there are three operation modes for Boost converters and Buck-Boost converters, i.e., the Complete Inductor Supplying Mode (CISM), the Incomplete Inductor Supplying with Continuous Conduction Mode (IISM-CCM) and the Incomplete Inductor Supplying with Discontinuous Conduction Mode (IISM-DCM). The critical conditions and the maximum output voltage ripple within the whole working range of a converter are obtained. It is concluded that the minimum inductance to guarantee the maximum output ripple voltage to be the lowest is the critical inductance of CISM and IISM in case of the lowest input voltage and the minimum load resistance. It is also found that the lowest output voltage ripple is independent of the inductance. The maximum output short-circuit discharged energy of a converter in the whole operating range is deduced. It is found that the maximum output short-circuit discharged energy relates to not only the output voltage and the capacitance but also the switching frenquency and the energy stored in the inductor. It is discovered that the ignition ability is affacted by the load and that the published ignation curve for simple capacitive circuit is not suitable for switching converters. To solve above problem, a new non-explosive output intrinsic safety criterion for switching converters based on modeling the output short-circuit discharging behaviour as a simple capacitive circuit is suggested, which is verified by the experiment results on IEC standard spark ignation apparatus. The maximum current through the inductor of a switching converter is deduced. It is discovered that although the current through the inductor of a switching converter is much lower than the corresponding value on the published ignition curve, ignition still occurs. It is also found that the ignition ability is stenghfened as the output capacitance becoming larger. To solve above problem, a new non-explosive intrinsic safety criterion for switching converters is suggested based on an equivalent resistance analysis approach, in which, the inductor disconnected discharging behavior of a switching converter is modeled as an equivalent simple inductive circuit with an equivalent resistance during the inductor disconnected instant. The proposed method is verified by the experiment results on IEC standard spark ignation apparatus. The approach to design an intrinsically safe switching converter is proposed. The design regions of inductance and capacitance to meet both requirements of electric performance and intrinsically safety are deduced. The influence of switching frequency on design is discussed. The minimum switching frequency of the output intrinsically safe switching converters and totally intrinsic safty switching converters are deduced, respectively.