A power inverter is a key power electronic device that converts direct current (DC) into alternating current (AC). Unlike devices that generate power, it relies on a DC source (such as batteries, solar panels, or fuel cells) for input, and its input voltage, output voltage, frequency, and power capacity vary based on design and application needs. It performs the reverse function of rectifiers, which convert AC to DC, and is distinct from oscillators (for low-current electronic signals) as it focuses on high-current, high-voltage electrical power scenarios.

The output waveform of a power inverter directly affects its usability. Basic models may produce square waves (with significant harmonics, suitable only for simple devices), while most practical ones generate modified sine waves (quasi-sine waves, usable for most household appliances) or pure sine waves (ideal for sensitive electronics like medical equipment and high-end audio systems). Common output frequencies match grid standards (50 Hz or 60 Hz globally), and output voltages align with regional device requirements (110-120 V in North America, 220-240 V in most other regions).

Power inverters have a wide range of applications. In off-grid or emergency scenarios, they let AC devices run on DC sources (e.g., RVs, boats, portable power stations during outages). They are core components of UPS systems, switching to battery power to keep critical equipment (computers, servers) operational when the grid fails. In renewable energy, they convert DC from solar panels/wind turbines to AC for grid feed-in. They also control electric motor speeds (via variable-frequency drives in HVAC or industrial machinery) and play roles in induction heating (cooktops, industrial heat treatment) and high-voltage power transmission.