The switch mode power supply working principle can be simply summarized as follows: the input voltage is pulse-width modulated (PWM) through a high-frequency switching device (such as MOSFET) to generate a high-frequency square wave, which is then transformed, rectified and filtered by a transformer to obtain the required output voltage. The entire working process can be divided into the following stages:
Rectification and filtering: The input AC (or DC) is converted into a relatively stable DC voltage through a rectifier bridge and a filter capacitor.
High-frequency switching conversion: The switch tube is controlled by a PWM controller to turn on and off periodically at a high frequency. When the switch tube is turned on, the input voltage is added to the primary of the transformer; when the switch tube is turned off, the primary of the transformer is disconnected from the input voltage.
Transformer conversion: The transformer converts the high-frequency square wave voltage into the required voltage and current.
How does a switching power supply work?
To help you know how does a smps work clearly, this part will introduce the working principle of switch mode power supply from AC to DC SMPS, DC to AC smps, Flyback converters SMPS, and Buck converter SMPS.
AC to DC SMPS working principle
The working principle of the switching power supply is relatively simple. First, the input AC power is converted into DC power through rectification. Then, these DC powers are quickly switched on and off through a high-frequency switch (usually MOSFET or IGBT) to generate high-frequency pulses. Then, these high-frequency pulses are converted into the required voltage through a transformer, and then restored to stable DC power through the rectification and filtering process, and finally output to the device.
DC to AC smps working principle
The DC-AC switching power supply modulates the input DC power through high-frequency switching, then increases or decreases the voltage through a high-frequency transformer, and finally outputs stable AC power after rectification and filtering. Modern DC-AC switching power supplies usually use PWM (pulse width modulation) control technology, which can ensure that the output AC power has a stable frequency and voltage.
Fly-Back Converter Type SMPS Working
working principle of Fly-Back Converter Type smps
A fly-back converters SMPS is any SMPS with an output power of less than 100W. The circuit for these SMPS is easy to understand and less complicated than that of other SMPS. Low power consumption is the purpose of this kind of SMPS. Using a MOSFET, the unregulated voltage that is input of constant intensity switches at a frequency of about 100 kHz to the desired output voltage. A transformer is used to achieve voltage separation. A workable fly-back converter can be operated while the switch is controlled via PWM. Unlike a typical transformer, the fly-back transformer exhibits unique qualities. The two windings that make up the fly-back transformer function as magnetically coupled inductors. To improve filtering, capacitors and diodes are used to spread the transformer’s output.
Buck converter SMPS working principle
The operation of the buck converter is based on the principle of storing energy in an inductor. The voltage drop across an inductor is proportional to the change in the electric current flowing through the device. A switching transistor is used in between input and output for continuous switches on and off at high frequency. To maintain a continuous output, the circuit uses the energy stored in the inductor.
Conclusion
Switch Mode Power Supplies (SMPS) are crucial components in modern electronics, offering high efficiency, compact design, and versatility for various applications. Whether converting AC to DC, DC to AC, or adjusting voltage levels, SMPS use high-frequency switching technology to optimize energy conversion and ensure reliable power delivery. With the ability to operate efficiently in a wide range of voltage and current conditions, SMPS have revolutionized the way electronic devices are powered. From power adapters to industrial applications, the use of SMPS continues to expand, providing more efficient and reliable solutions for power conversion.
