Inverter is a device for converting direct current into alternating current with a change in voltage value. Usually it is a generator of periodic voltage, in the form of an approximate sinusoid, or a discrete signal.
Voltage inverters can be used as a separate device or as part of uninterruptible power supplies and systems for equipment with AC electrical energy.
Voltage inverters can eliminate or at least weaken the dependence of the operation of information systems on the quality of AC networks. For example, in personal computers, in the event of a sudden network failure, using a backup battery and an inverter, which form an uninterruptible power supply (UPS), it is possible to ensure the operation of computers for the correct completion of the tasks being solved. In more complex critical systems, inverter devices can operate in a continuous controlled mode in parallel with the grid or independently of it.
In addition to “independent” applications, where the inverter acts as a power source for AC consumers, energy conversion technologies have been widely developed, where the inverter is an intermediate link in the chain of converters. A fundamental feature of voltage inverters for such applications is a high conversion frequency (tens to hundreds of kilohertz). For efficient energy conversion at high frequency, a more advanced element base (semiconductor switches, magnetic materials, specialized controllers) is required.
Like any other power device, the inverter must have a high efficiency, high reliability and have acceptable weight and size characteristics. In addition, it must have a permissible level of higher harmonic components in the output voltage curve (permissible value of harmonic coefficients) and not create during operation an unacceptable ripple level for other consumers at the terminals of the power source.
In pure grid-tie metering systems, an inverter is used to supply energy from solar panels, wind turbines, hydroelectric power plants and other green energy sources to the grid.