What is the meaning of high frequency switching rectifier

High-frequency switching rectifiers are a major component of modern communication power systems. The operating frequency of this type of switching rectifier is generally in the range of 30 to 60 kHz (IGBT), and the MOSFET power converter tube can reach several hundred kilohertz. Therefore, they are characterized by high efficiency, high power density, small size and wide input voltage range.

This chapter mainly introduces the circuit composition of the switching rectifier module and the function of each part, several typical traditional power conversion circuits in the rectifier module, as well as the characteristics, parameters and basic applications of commonly used power devices and protection circuits of the rectifier module. And briefly introduce the high-frequency soft-switching technology developed in recent years.

Structure and Block Diagram of High Frequency Switching Rectifier Module

The block diagram of the structure of the high-frequency switching rectifier module is shown in Figure 3-1. The block diagram contains input filter circuit, rectifier circuit, power factor correction circuit, DC/DC power conversion circuit, filter output circuit, auxiliary power supply and monitoring circuit. The functions of each part of the circuit are described as follows.

1. Input Filter Circuit

This part of the circuit includes low-pass filtering and surge voltage absorption circuits, which are mainly used to suppress the high harmonic currents, common mode noise and differential mode noise, surge voltage and radio frequency interference from the outside space on the grid side.

2. Rectifier circuit

This part of the circuit is just a single-phase or three-phase alternating current into a pulsating DC voltage, all the rectifier module is used as a rectifier bridge rectifier circuit.

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3. Power factor correction circuit

This part of the circuit is used to suppress the harmonic components of the input current, so that the input current waveform closer to sinusoidal less reactive power, but also purifies the AC power grid. Power factor correction is divided into passive correction and active correction, the former generally used for three-phase input rectifier, power factor can be corrected to 0.92 ~ 0.94, while the latter can be corrected to 0.999.

4. DC/DC converter circuit

This part of the circuit consists of high-frequency power conversion and rectifier circuits, high-voltage DC power supply into -48V or -2 low-voltage DC power supply.

5. Output Filter Circuit

PWM-type switching rectifier output main circuit lead-to-lead noise consists of sawtooth wave noise, spike noise and low-frequency modulation noise, the output filter composed of LC is mainly to filter out the sawtooth wave and spike noise.

6. Auxiliary power supply

Auxiliary power supply is generally a small power DC/DC converter. It is mainly for the PWM control circuit monitoring circuits, protection circuits and display power supply.

7. Protection circuit

Protection circuit is an important and indispensable part of the power supply circuit, the input protection is mainly to prevent damage caused by high input voltage, the output protection is mainly to prevent the output overcurrent or short circuit damage to the power supply. In addition, there is over-temperature protection is to stop the ambient temperature is too high or due to other reasons caused by the high temperature inside the machine resulting in damage to the power device.