DC power supply is widely used in the industrial field
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 adjustment range; Another type of quality indicator is used to measure the stability of the output DC voltage, including the voltage stabilization coefficient (or voltage regulation rate), output resistance (or current regulation rate), and ripple voltage (surrounding and random drift).
Design of the Main Circuit of DC Switching Power Supply
The main circuit of the DC switching power supply is used to complete the conversion of DC-AC-DC, and the main circuit of the system 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 the BSM 50GB120DN2 series, with each module having a half bridge structure. Therefore, in a full bridge system, two modules are required. Each module is embedded with a fast freewheeling diode.
DC switching power supply has 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 sources are required, and they generally require a DC power supply that can conveniently adjust the voltage output. At present, due to the advantages of high efficiency and miniaturization of switching power supplies, traditional linear regulated power supplies and thyristor regulated power supplies are gradually being replaced by DC switching regulated power supplies. The main control method of switching power supply is to use a pulse width modulation integrated circuit to output PWM pulses, and use an analog PID regulator for pulse width modulation. This control method has certain errors and the circuit is relatively complex.
operational principle
The 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 conversion function required for output. It mainly consists of a switching transistor and a high-frequency transformer. Figure 1 shows the schematic diagram and equivalent schematic diagram of a DC switching power supply, which is composed of a full wave rectifier, switching transistor V, excitation signal, freewheeling diode Vp, energy storage inductor, and filtering capacitor C. In fact, the core part of a DC switching power supply is a DC transformer.
