直流电流(Direct current)，可从通过使用称为整流器包含电子组件（通常情况下）或机电组件（在历史上），使电流只在一个方向流动的电流开关装置的交流电流供给。直流电流可以由成交流电流的逆变器或电动发电机组。

第一个商业化的电力传输，由托马斯·爱迪生在十九世纪后期开发，使用直流电。由于直流电流超过交替转化和传输的显着优势，今天几乎所有的电力分配交流电。在20世纪50年代中期，HVDC传输，现在是一个选项，而不是远距离高电压交流电系统。对于应用要求，如第三铁路电力系统直流，交流电被分配到一个变电站，它利用一个整流电源转换为直流电流。

Direct current (DC) is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, power supplies, thermocouples, solar cells, or dynamos. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.