DC switching power supplies are widely used in industrial fields
The technical indicators of DC power supply are divided into two types: one is the characteristic indicator, including the allowable input voltage, output voltage, output current and output voltage adjustment range, etc.; the other is the quality indicator, which is used to measure the stability of the output DC voltage. Including voltage regulation coefficient (or voltage regulation rate), output resistance (or current regulation rate), ripple voltage (surrounding and random drift).
DC switching power supply main circuit design
The main circuit of the DC switching power supply is used to complete the conversion of DC-AC-DC. 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 BSM 50GB120DN2 series IGBT module. Each module is a half-bridge structure, so in a full-bridge system, two modules are required. A fast freewheeling diode is embedded in each module.
DC switching power supply has been widely used in many industrial fields. In industrial production (such as welding, electroplating or DC motor speed regulation, etc.), a large number of voltage-adjustable DC power supplies are needed. They generally require a DC power supply that can easily 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 replaced by DC switching regulated power supplies. The main control method of the switching power supply is to use a pulse width modulation integrated circuit to output PWM pulses and an analog PID regulator to perform pulse width modulation. This control method has certain errors and the circuit is relatively complex.
working principle
DC switching power supply consists of input part, power conversion part, output part and control part. The power conversion part is the core of the switching power supply. It performs high-frequency chopping of unsteady DC and completes the conversion functions required for output. It is mainly composed of switching transistors and high-frequency transformers. Figure 1 shows the schematic diagram and equivalent principle block diagram of a DC switching power supply. It is composed of a full-wave rectifier, a switching tube V, an excitation signal, a freewheeling diode Vp, an energy storage inductor and a filter capacitor C. In fact, the core part of the DC switching power supply is a DC transformer.
