If the flyback switching power supply is not loaded, how is the magnetic energy stored in the primar

Hello, this problem is very easy to explain, the energy stored by the transformer when the flyback switching power supply is no-load, there is a charge for the post-stage capacitor, and the false load is also absorbed by RCD (not all, RCD only absorbs the energy generated by the transformer leakage inductance, and consumes it with R heating), as well as the MOS tube, and the switching loss of the post-stage rectification, because there is a turn-on and turn-off, it must be a loss, just a matter of size, the duty cycle of the switch tube conduction at no load is very small, So the stored energy is very small (as far as the transformer is concerned, not to mention the pre-amp capacitor, you are also asking about the transformer), the loss of the machine itself is very small (but there must be a loss when each component is energized), used to maintain the voltage stabilization of the power supply, feedback, etc., you can add a power meter at the input AC end, and the power loss is generally less than 1W, so it is very small.

The switch is turned on, the primary side coil is energy storage, and the secondary load is powered by the capacitor;

The switch is off, and the energy of the primary coil is released to the secondary side, which charges the capacitor and supplies power to the load.

In this case, if no load is applied, the energy stored in the primary coil is only used to charge the capacitor.

The primary is connected to RC or RDC absorption circuit, that is, a fast recovery diode and a resistor are stringed at both ends of the primary coil, and then a high-voltage ceramic capacitor is combined at both ends of the resistor. However, this is used to absorb the higher harmonic components during operation, not for venting.

After the switching power supply is unplugged without load, the secondary energy storage will generally be slowly consumed by the indicator light or false load, and the primary energy storage will be slowly consumed when transmitted to the secondary, if there is no indicator light and no false load, it doesn't matter, the inductive energy storage device is easy to consume energy by radiating magnetic energy outward, and it will be consumed after a few minutes.

The real energy storage in the switching power supply is the high-voltage electrolytic capacitor after the front rectification, because the MOS tube is disconnected, there is no discharge circuit, the electric energy of this capacitor is stored for a long time, and even a power supply you throw there for a few years, you open the cover and touch it will be electrified.

The working principle is different, the transformer (magnetic material) of the flyback switching power supply is energy storage, and the magnetic material of the forward switching power supply is the energy transfer effect, if a working cycle is completed, the magnetic material is not degaussed (reset), it will produce cumulative magnetic saturation, which will greatly reduce the efficiency and even burn the power tube, so the magnetic reset of the forward switching power supply is a must!

Explain the working process of flyback switching power supply, magnetization - > magnetic discharge (charging the secondary circuit) - > magnetization.

The process of forward magnetization and the process of secondary charging are simultaneous.