变流技术是一种电力变换的技术，相对于电力电子组件制造技术而言，是一种电力电子组件的应用技术，它的理论基础是电路理论。变流技术主要包括：用电力电子组件构成各种电力变换的电路，对电路进行控制，以及用这些技术构成更为复杂的电力电子装置和系统．通常所说的“变流”是包含：交流电变直流电（AC-DC变换）、直流电变交流电（DC－AC变换）、直流电变直流电（DC-DC变换）和交流电变交流电（AC-AC变换）等四大类。

例如，我们常见的充电器，就使用了交流电变直流电的变流技术。

In electrical engineering, power engineering and the electric power industry, power conversion is converting electric energy from one form to another, converting between AC and DC, or just changing the voltage or frequency, or some combination of these. A power converter is an electrical or electro-mechanical device for converting electrical energy. This could be as simple as a transformer to change the voltage of AC power, but also includes far more complex systems. The term can also refer to a class of electrical machinery that is used to convert one frequency of alternating current into another frequency.