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Precautions for Central and Parallel Connection of Switching Power Supply

Generally speaking, when choosing a power supply, it is recommended to choose a power supply with sufficient voltage, current, and power. However, in some special applications, for example, when the voltage or current required by the load is too large and the existing power supply cannot meet the requirements, it may be necessary to connect the power supplies in series or parallel to meet the load requirements. However, the series and parallel connection of power supplies is not simply a matter of connecting multiple power supplies. There are some matters that need to be paid attention to when performing series or parallel operations.

Series connection

The series connection of power supplies generally involves connecting lower voltage power supplies in series to obtain a higher voltage. When performing series operation of power supplies, you need to pay attention to:
The power supplies connected in series must be isolated power supplies, that is, the positive and negative poles of the power supply output are floating and isolated from the ground.
The total voltage after series connection cannot exceed the isolation voltage of the power supply.
Power supplies with different voltages can be connected in series, but it is recommended that the rated current of the power supplies be the same, otherwise the output current after series connection cannot exceed the minimum rated current.
It is recommended to add diodes in the series circuit to prevent reverse current in the circuit from damaging the power supply.

Parallel connection

The power supplies connected in parallel must be of the same model and specifications to ensure that the output voltage of the power supply is the same as the internal circuit to prevent the power supply from burning out due to the current generated due to the potential difference between the two power supplies.
When connecting in parallel, design current sharing control to adjust the output current of each power supply to make it approximately equal to prevent some power supplies from burning out due to unbalanced load distribution.
Even for power supplies of the same model and specifications, their output voltages may be slightly different. Therefore, when connected in parallel, a diode needs to be connected in series at the output end of the power supply to prevent current from damaging the power supply.

In short, the power supply can be operated in series and parallel, but there are certain requirements for the design of the power supply and circuit.
In addition, connecting power supplies in series or parallel is only recommended for short-term use. If long-term use is required, it is recommended to replace it with a power supply whose voltage and current can meet the requirements.

Updated on: 14/03/2024

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