Let ordinary single-phase mains switching power supply adapt to three-phase four-wire system

DFN1006 TP-RCLAMP3321P ESD Diode Low Capacitance

The 220V single-phase power supply has the potential to be converted into a three-phase power supply. The method is simple: use three rectifier diodes instead of the original rectifier full bridge, as shown in the figure:



The filter capacitor is not shown in the figure, and Load represents the subsequent circuit.
The transformation is very simple. Why can it be transformed?
As you can see, in our three-phase four-wire power supply system, there are three phase lines (fire line UVW) and one neutral line (zero line N), each phase line has 380V (phase voltage), each The root-phase line has a 220V (line voltage) for the neutral line and a phase difference of 120 degrees between the adjacent phase lines. Therefore, half-wave rectification can be performed for each phase line to achieve the effect of single-phase 220V full-bridge rectification.
So what are the advantages of a three-phase half-wave rectifier circuit?
First, a power supply with a large current supply capability can be used; second, a smaller number of diodes is used; third, the filtered ripple is smaller; and four, three-phase half-wave rectifier circuits are not afraid of phase loss, when the UVW is lacking When any one or two phases are used, the circuit can still work barely. When the N phase is missing, the circuit will be cut off, but the device will not be damaged.


The black in the figure represents the voltage of the three phases, and the red line represents the filtered voltage.
Why is the three-phase half-wave rectification more fierce than the mains rectification? Because the time interval of the peak voltage of the diode output in the three-phase half-wave rectification circuit is smaller than that of the single-phase full-wave, meaning that the capacitor replenishes the electric energy faster, so For the same load and ripple requirements, three-phase half-wave rectification can use smaller filter capacitors.
After reading this article, try to modify several switching power supplies.