Table Of Contents
Power supply is everywhere in life. Power supply is a specific device that converts other forms into electrical energy. Power supply can be divided into ordinary power supply and special power supply. Among them, ordinary power supply can be subdivided into switching power supply, inverter power supply, AC regulated power supply, DC regulated power supply, DC/DC power supply, module power supply, variable frequency power supply, UPS power supply, EPS emergency power supply, PC power supply, rectifier power supply, etc. Among them, switching power supply is the most common one. Let’s learn about some basic common sense and principles of switching power supply.
The working principle of the switching power supply is essentially to change the output voltage or current by changing the conduction time of the adjustment tube in the circuit, in order to achieve the purpose of maintaining the output voltage or current stable.
In AC-DC power conversion, the mains electricity is rectified into high-voltage DC, and then converted into the low-voltage DC required by the load through DC-DC. Therefore, the DC-DC converter is the core component of the switching power supply, so the DC-DC switching power supply is also called a DC-DC converter (Note: Because the adjustment of the DC-DC switching power supply works in the on [ON] and off [OFF] states, it is also called a switching tube. Because the main function of the adjustment tube is to perform power conversion, it is also called a power tube or a power switching tube.)
DC-DC converter: DC-DC converter is the most common type of switching power supply, which is composed of diodes, transistors, capacitors, etc. DC-DC converter is to repeatedly switch on and off, convert DC voltage or current into high-frequency square wave voltage or current, and then smooth it into DC voltage output after rectification. DC-DC converter is composed of basic components such as semiconductor switch, rectifier diode, smoothing filter reactor and capacitor. When electrical isolation is required between input and output, a transformer can be used to transmit the high-frequency square wave voltage to the output side through the transformer. Basic components that constitute DC-DC converter.
By increasing the switching frequency, magnetic devices such as filter inductors, switching transformers, and filter capacitors can be made small and lightweight. For DC-DC converters, the waveform of the voltage US applied to both ends of the switch S is approximately a square wave, while the waveform of the current IS passing through is approximately a triangular wave or a triangular wave with steps.
| Features and Advantages | Description |
| High efficiency | Due to the switching operation mode, the DC-DC converter can achieve high conversion efficiency under proper design and reduce energy loss. |
| Miniaturization | With the development of integrated circuit technology, the DC-DC converter can be integrated into small chips, saving space and being convenient for use in various electronic devices. |
| Wide input voltage range | It can adapt to different power inputs, such as battery voltage changes and different power adapters. |
| Stable output voltage | Through the feedback control mechanism, the output voltage can be precisely adjusted to maintain stability under load changes and input voltage fluctuations. |
Features and advantages of DC-DC converters for switching power supplies
The methods for controlling the duty cycle of the switching waveform of the DC-DC converter include keeping the duty cycle T unchanged, controlling the pulse width modulation PWM of the switch on/off time, and keeping the on time ON unchanged, changing the frequency modulation (PWM) of the duty cycle T. However, when the switching frequency is low, the frequency modulation PFM method requires a larger isolation transformer and input/output filter, which is not only uneconomical, but also too large in size, which is difficult to accept in reality. Therefore, the switching frequency of this working method must be high enough.
The above is a brief introduction to the working principle of the DC-DC converter based on the switching power supply.
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