A frequency converter is an electrical device that converts mains frequency power into AC power of any frequency and voltage. The main purpose of a frequency converter is to adjust the power of a motor and achieve variable speed operation. A frequency converter mainly consists of two parts: a control circuit and a main circuit. The main circuit further includes components such as a rectifier and an inverter.
The working principle of a frequency converter is to control the main circuit through the control circuit. The rectifier in the main circuit converts AC power into DC power, the DC intermediate circuit smooths and filters the DC power, and the inverter finally converts the DC power back into AC power with the required frequency and voltage. Some frequency converters also add components such as CPU to the circuit to perform necessary torque calculations.
The invention of frequency converters originated from the need for stepless speed regulation of AC motors. With the emergence of components such as thyristors, electrostatic induction transistors, and high-voltage insulated gate bipolar thyristors, electrical technology has undergone rapid changes, and frequency converter speed regulation technology has also developed accordingly. In particular, pulse width modulation variable frequency speed regulation technology has brought frequency converters to a new level.
The power supply of a frequency converter is typically 50Hz or 60Hz. Whether in household or industrial applications, the frequency and voltage of the power supply remain constant. Motors operating on a power supply at this frequency may experience a power decrease when their speed is adjusted. However, by adjusting the speed using a frequency converter, this power loss can be reduced.
There are many types of frequency converters . According to their different uses, they can be divided into general-purpose frequency converters, high-performance special-purpose frequency converters, high-frequency frequency converters, single-phase frequency converters, and three-phase frequency converters. According to their working principle, they can be divided into V/f control frequency converters, slip frequency control frequency converters, and vector control frequency converters.
