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EnglishThe power adapter is a common electrical accessory in life, but most people are not very clear about the structure of the power adapter. Today let's take a look at the advantages and disadvantages of five classic switching power supply structures.
1. Single-ended forward excitation
Single-ended: One-way drive pulse transformer through switching device.
Forward: The phase relationship between the primary and secondary sides of the pulse transformer to ensure that when the switch is turned on, the primary side of the pulse transformer is driven and the effective load on the transformer side is driven.
2. Single-ended flyback
In contrast to a positive feedback circuit, the raw/paid phase relationship of the pulse transformer ensures that when the switch is on and the primary side of the pulse transformer is driven, the branch of the transformer does not supply power to the load, i.e. the primary/paid side is staggered on/off. The magnetic energy accumulation problem of the pulse transformer is easy to solve, but due to the leakage inductance of the transformer, a voltage spike will be formed on the primary side, and the switching device will be broken down. Need to build a circuit consisting of d3 and n3 and a voltage clamp circuit. From the circuit schematic, flyback and forward phase are very similar. Transformers have the same name on the surface, but the circuit works differently, and d3 and n3 do different things.
3. Push-Pull (central pump transformer)
The circuit structure has the characteristics of symmetrical structure, two symmetrical coils on the main side of the pulse transformer, symmetrical connection of two switches, and rotation interruption. Its working process is similar to that of a class B push-pull power amplifier in a linear amplifier circuit.
4. Full bridge
This circuit structure features four identical switches connected to the bridge structure driving the primary side of the pulse transformer.
Main advantage: Compared to push-pull configuration, the primary winding is reduced by half and the pressure switch is reduced by half.
Main disadvantages: large switching volume, good parameter consistency, complex driving circuit, and difficulty in achieving synchronization. This circuit structure is usually used in ultra-high power switching power supply circuits with power greater than 1kw.
