Invertoare

Invertoare are power electronic devices that convert direct current (DC) into alternating current (AC). They enable DC sources, such as solar panels, batteries, or fuel cells, to feed AC equipment and to interface with electrical grids. Modern inverters support various waveforms, with pure sine wave being standard for sensitive electronics.

They come in several configurations: grid-tied inverters that synchronize with the utility grid; off-grid or standalone inverters that operate independently; and battery-based or hybrid inverters that manage energy storage. Topologies include central or string inverters for large installations and microinverters mounted on individual panels. Waveforms include pure sine wave, modified sine wave, and quasi-sine wave, with pure sine wave offering best compatibility.

Operation relies on high-power semiconductor switches (IGBTs, MOSFETs) controlled by PWM to approximate AC sine waves. Input DC quality, switching losses, efficiency, and heat management determine performance. Typical efficiencies for modern devices range from about 95% to 98% under rated load.

Applications include solar photovoltaic systems, uninterruptible power supplies, and motor drives. In power grids, inverters must meet interconnection standards and safety requirements, such as anti-islanding and voltage/frequency support; regulatory standards vary by region, including IEEE 1547 in the United States and similar protocols elsewhere.