Definition
An inverter is the switching stage that converts DC (typically from a drive's DC link) into AC output at a controlled frequency and voltage using power semiconductors such as IGBTs, most often through pulse-width modulation. It is the specific circuit that produces a VFD's variable-frequency output, rather than the complete packaged drive.
Key facts
- Converts DC (from a rectifier or battery/DC bus) into AC output; the reverse of a rectifier.
- Most industrial inverters use pulse-width modulation (PWM) with IGBT or similar power switches to synthesize the output waveform.
- It is a stage inside a VFD, not a separate standalone drive: a VFD combines rectifier, DC link, inverter, and control.
- Output switching frequency and dead-time settings affect motor heating, audible noise, and EMI.
How does Inverter work or appear?
An inverter takes a DC input and switches power semiconductors in a defined pattern (typically pulse-width modulation) to synthesize an AC output whose effective frequency and voltage can be varied. The switching pattern approximates a sine wave closely enough for the connected motor or load to run smoothly at the commanded frequency.
What should technicians inspect for Inverter?
A VFD is the complete drive package (rectifier, DC link, inverter, and control logic) of which the inverter is one internal stage. A frequency converter and VFD name the same complete device, so "inverter" is narrower than both: it is the electrical conversion, not the packaged product.
FAQ
Frequently asked questions
What electrical conversion does an inverter perform?
It converts DC input into AC output at a controlled frequency and voltage, typically using pulse-width modulation, so a motor or other AC load can be driven from a DC source such as a VFD's DC link.
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