Power module selection is not easy, it must take into account a lot of difficult, how much do you know?

Magnetic beads, capacitors, secondary tubes, resistors... They all have similar inside stories, but people don't pay much attention to them. The topological structure of the power supply module is various, such as flyback, forward excitation, push-pull, half-bridge and full-bridge. Due to the difference of its basic principle, each of them is mainly manifested as its advantage in some characteristic index level.

Flyback power supply in the power switch is in a period of time, there is no charge and discharge the battery time period, that is because of the characteristics of the time no response characteristics, grain potter points can't guarantee is very good, although may according to the energy storage capacitor help with little, but the basic principles is just a defect.

Leakage inductance is also a big problem, but its advantages are simple power circuit, low cost, light weight, no need to add magnetic calibration winding, and typing working voltage range is wider. Also because of this, it has its share of the total power supply sales market of about 7 percent.

Positive power output voltage transient operation features good, load capacity is strong, but its defects are also obvious, to use a large energy storage technology filter inductor and a continuing diode, large volume, transformer primary coil counter electromotive force working voltage is high, the provision of power switch tube is high.

Push-pull power supply has high transient response time and good working voltage and frequency characteristics. It is the power transformer with the highest utilization rate among all topologies. It has no magnetic leakage and simple optocoupler circuit.

If the two forward converters are not completely symmetrical or balanced, the magnetic bias accumulated over many cycles will make the magnetic core into a saturated state, resulting in excessive excitation current of the high-frequency transformer and even damage to the power switch tube.

The power of the cumulative unchained power transformer is quite large, the working efficiency is very high, the voltage withstand test value of the power switch tube is relatively low, and the transformer primary coil only needs 1 winding. The defect is low efficiency, semi-conduction zone and large consumption.

All of the above problems are caused by the inherent advantages and disadvantages of its topology. Although people can use the power module as the black box of an airplane, this is a point of concern when selecting the power supply.