Switching power supply damage is the most common failure of many inverters, usually due to the switching power supply occurs, when the occurrence of no display, no voltage at the control terminals, DC12V, DC24V fan does not turn and other phenomena, the first thing you should consider is whether the switching power supply is damaged. Switching power supply damage is an obvious characteristic of inverter power on no display. For example, Fuji G5S inverter uses a two-stage switching power supply, the principle of which is that the DC voltage of the main DC circuit is reduced from 500V or more to 300V or so, and then a level of switching step-down output 5V, 24V multi-channel power supply. Switching power supply damage is common switching tube breakdown, pulse transformer burnout, and secondary output rectifier diode damage, filter capacitors used for too long, resulting in changes in capacitance characteristics (reduced capacity or leakage current is larger), the voltage regulator ability to decline, but also easy to cause damage to the switching power supply. For example, the switching power supply of the MF series inverter adopts the more common flyback switching power supply control mode, and a short circuit in the output stage circuit of the switching power supply can also cause damage to the switching power supply, which leads to no display of the inverter. The reasons for damage to the switching power supply are as follows:
(1) Environmental pollution, due to dust, moisture and other insulation damage. Switching power supply due to local high temperature has made the depth of the printed board yellowing carbonisation or printed line damage, the insulation of the printed board and copper-clad foil, wire can not be used, can only be replaced as a whole the printed board. After finding out the damaged components and replace them with new ones, the component model should be the same as the prototype number, and when it cannot be the same, it should be confirmed that the component's power switching frequency, withstand voltage, and the size can be installed, and it should be insulated with the peripheral components to maintain insulation spacing.
(2) Components itself life problems, especially switching tube or switching integrated circuit due to the current and voltage burden, more likely to be damaged.
(3) switching transformer enamelled wire used for a long time at high temperatures appear yellowing, burnt, between the transformer winding breakdown, transformer winding, especially the high-voltage winding has broken wire, skeleton deformation and traces of arc jumping. Transformer wire due to oxidation, flux corrosion and breakage over time.
(4) switching power supply transformer itself leakage inductance, operation of the primary winding leakage inductance caused by large energy overvoltage, the energy is absorbed by the absorption of the components (resistive components, voltage regulator, transient voltage suppression diode) absorption of the serious overload occurs, a long time to absorb the components will be damaged.
