Frequency converter is a common component in electronic products. Do you know how the frequency converter works? Let's take our common AC-DC-AC converter as an example to understand the working principle of down converter through its working schematic diagram.

Schematic diagram of AC -DC- AC frequency converter

As can be seen from the figure, the frequency converter consists of main circuit (including rectifier, intermediate DC link and inverter) and control loop. The functions of each part are as follows:

1. Rectifier is used to rectify three-phase (or single-phase) AC power supply into DC power supply. In SPWM inverter, full-wave rectifier circuit is mostly used. In most small and medium capacity frequency converters, uncontrolled rectifier diodes or diode modules are used as rectifier devices.

2. Contrary to the rectifier, the inverter converts direct current into variable-voltage and variable-frequency alternating current to realize variable-frequency speed regulation of AC motor. The inverter circuit is composed of switching devices, and most of them use bridge circuits, which are usually called inverter bridges. In SPWM inverter, the switching devices in the control circuit are controlled by SPWM modulation signals to convert DC into three-phase AC.

3. Control circuit This part of the circuit consists of arithmetic circuit, detection circuit, driving circuit and protection circuit. Generally, large-scale integrated circuits are used.

Through the above analysis of the working principle diagram of frequency converter, do you have a deeper understanding of its working principle?