Widely used in industrial applications, DC switching power supplies
The technical indicators of DC power supply are divided into two types: one is characteristic indicators, including allowable input voltage, output voltage, output current, and output voltage regulation range, etc; Another type is quality indicators, which are used to measure the stability of the output DC voltage, including voltage stabilization coefficient (or voltage regulation rate), output resistance (or current regulation rate), and ripple voltage (surrounding and random drift).
Design of Main Circuit for DC Switching Power Supply
The main circuit of the DC switching power supply is used to complete the conversion of DC-AC-DC. The system main circuit adopts a full bridge DC-DC converter, as shown in Figure 2. The power switching device used in this system is the IGBT module of BSM 50GB120DN2 series, each module is a half bridge structure, so two modules are required in the full bridge system. Each module is embedded with a fast freewheeling diode.
DC switching power supplies have been widely used in many industrial fields. In industrial production (such as welding, electroplating, or speed regulation of DC motors), a large number of voltage adjustable DC power supplies are required, and they generally require DC power supplies that can easily adjust the voltage output. At present, due to the advantages of high efficiency and miniaturization of switching power supplies, traditional linear and thyristor stabilized power supplies are gradually being replaced by DC switching stabilized power supplies. The main control method of switch mode power supply is to use pulse width modulation integrated circuit to output PWM pulses, and use analog PID regulator for pulse width modulation. This control method has certain errors and the circuit is relatively complex.
working principle
A DC switching power supply consists of an input part, a power conversion part, an output part, and a control part. The power conversion part is the core of the switching power supply, which performs high-frequency chopping on unstable DC and completes the required conversion function for output. It is mainly composed of a switching transistor and a high-frequency transformer. Figure 1 shows the schematic and equivalent schematic diagram of a DC switching power supply, which consists of a full wave rectifier, a switching tube V, an excitation signal, a freewheeling diode Vp, an energy storage inductor, and a filtering capacitor C. In fact, the core part of a DC switching power supply is a DC transformer.
