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该文提出了一种直流–直流自耦变压器的拓扑，用于互联两个电压等级不同的高压直流系统。常规的隔离型直流–直流变换器一般需要经过直流–交流–直流两级交/直变换，两个互联的直流系统之间没有直接的电气连接，而直流自耦变压器所互联的两个直流系统之间有直接的电气连接，只有部分互联功率需要经过两级交流/直流变换。为此，直流自耦变压器所使用的换流器总容量低于常规直流–交流–直流变换技术。该文详细介绍了直流自耦变压器的拓扑，推导了直流自耦变压器中每个换流器的额定直流电压和额定功率的设计方法，设计了直流自耦变压器的控制策略，在PSCAD/EMTDC 下仿真验证了直流自耦变压器的可行性。研究结果表明，所提出的直流自耦变技术能显著降低所使用的换流器容量，并降低运行损耗。“,”This paper proposes a dc-dc autotransformer for connecting two dc grids with different dc voltage levels. The dc-dc autotransformer is able to make use of the already existed dc voltage of the dc grid with lower voltage. Compared with conventional dc/dc converter employing full power dc/ac/dc conversion, the dc-dc autotransformer is able to reduce the total used converters to about half of a conventional dc/dc converter. Typical topologies of the dc-dc autotransformer are proposed in this paper. The ways of designing the voltage and power rating of the converters in the dc-dc autotransformer are mathematically deduced. Controllers for the dc-dc autotransformer are designed. Simulations in PSCAD/EMTDC validate the feasibility and benefits of the dc-dc autotransformer.