![]() Switching power supplies have two main modes of operation: forward conversion and boost conversion. They differ in that the output of the error amplifier (error voltage) passes through a voltage pulse conversion unit before driving the power transistor. This means that the controller's functional block voltage reference and error amplifier designed to be identical to a linear regulator. The main purpose of the controller is to ensure that the output voltage is stable, and its working process is very similar to a linear controller. Finally, a DC output voltage is obtained after these AC waveforms are rectified and filtered. The number of voltage groups of the output can be increased by increasing the number of secondary windings of the transformer. Once the input voltage clamps into an AC square wave, its amplitude can be raised or lowered by the transformer. The duty ratio of the pulse is regulated by the controller of the switching power supply. The product of volt-ampere on a power device is the loss produced on a power semiconductor device.Ĭompared with linear power supplies, PWM switching power supplies work more efficiently by "chopper", which is to convert the input DC voltage into a pulse voltage with an amplitude equal to the input voltage amplitude. The volt-ampere product applied to the power transistor is always small in both states (the voltage is low and the current is large when turned on the voltage is high and the current is small when turned off). The PWM switching power supply, unlike a linear power supply, allows the power transistor to flip between on and off states. In a linear power supply, the power transistor is operating in a linear mode. It is quite easy to understand the working process of the switching power supply. In addition, the switching power supply requirements are higher efficiency, better performance and higher reliability.ġ2V 10A switching power supply (with schematic and explanation) Ⅱ The Basic Principle of Switching Power Supply 2.1 The Basic Principle of PWM Switching Power Supply Therefore, requirements of small size and lightweight are imposed on the switching power supply, including the volume and weight of magnetic components and capacitors. Many electronic devices need a smaller and lighter power supply, such as aerospace, submarine, military switching power supplies, and battery-operated portable electronic devices (such as portable calculators, mobile phones, etc.) ![]() ![]() As ULSI chips continue to shrink in size, power supplies are much larger than microprocessors. It is known as the 20 kHz revolution in the history of power supply technology development. It replaces a PWM switching power supply with a working frequency of 20 kHz, which can save energy. The linear power supply works at the power frequency. In the era of the global energy crisis, it has aroused widespread concern. The efficiency of the PWM switching power supply can reach 65%~70%, while the efficiency of the linear power supply is only 30%~40%. It characterizes 20kHz pulse frequency or pulse width modulation. It uses to control the switching converter to get PWM switching power supply. But, after the power transistor is in the switching state, pulse width modulation (PWM) control technology has developed. The main circuit topology is like that of the linear power supply. The first to appear in the series switching power supply. XVI Frequently Asked Questions about Switching Power Supplyįor more than 30 years, the switching power supply has supplanted the transistor linear power supply. XII Input Over/Under Voltage Protection Circuitġ3.3 The Voltage Regulated Principle of Battery Chargingġ3.4 The Principle of Battery Charging Current Limitingġ3.5 The Principle of Battery Undervoltage Shutdown ![]() Ⅹ Principle of Output Overvoltage Protection Circuitġ0.1 Thyristor Trigger Protection Circuitġ0.2 Photoelectric Coupling Protection Circuitġ0.3 Output Voltage Limiting Protection Circuit Ⅸ Output Current Limiting Protection Circuit Ⅳ Principle of Input Circuit and Common CircuitĤ.1 Principle of AC Input Rectification and Filtering Circuitĥ.3 Power Conversion Circuit with Drive Transformer Ⅲ Circuit Composition of the Switching Power Supply Ⅱ The Basic Principle of Switching Power SupplyĢ.1 The Basic Principle of PWM Switching Power SupplyĢ.2 Working Principle of Switching Power Supply Ⅰ Development History of Switching Power Supply
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