Control Loop Fault Analysis
The lifespan of variable frequency power supplies is affected by the power section, specifically the smoothing capacitors and the IPM circuit board's buffer capacitors, whose longevity is primarily determined by temperature and operating time. Since the capacitors are all soldered onto the circuit board, it is difficult to assess degradation by measuring the static capacitance. Generally, the approach is to estimate whether they are nearing the end of their lifespan based on the capacitors' environmental temperature and usage duration.
A power supply short circuit occurred, damaging the rectifier circuit on that particular line and potentially affecting other parts of the power supply. For instance, if the control power supply is accidentally shorted to the common ground due to improper operation, it can cause damage to the switch power supply section on the power circuit board. Additionally, a short circuit in the fan power supply can lead to power outages in other circuits. Generally, it is easy to identify by inspecting the power circuit board.
Cooling System: Avionics Ground Power 2, 36V Avionics Power 1, 400Hz Variable Frequency Power 7, 115/200V Power 2, 27V DC Power 5, 400Hz Power 12, Avionics Power
The cooling system primarily consists of radiators and cooling fans. The cooling fans have a shorter lifespan; as they approach the end of their service life, they begin to vibrate, increase noise, and eventually stop rotating, leading to an IPM overheating trip in the variable frequency power supply. The lifespan of the cooling fans is compromised by the bearings, typically ranging from 10,000 to 35,000 hours. When the variable frequency power supply operates continuously, a fan or bearing replacement is required every 2 to 3 years. To extend the fan's lifespan, some products' fans only operate during the variable frequency power supply's operation, not when the power is on.
3. External electromagnetic induction interference
If there are interference sources around the variable-frequency power supply, they may intrude into the internal circuit of the power supply through radiation or power lines, causing the control circuit to malfunction, leading to abnormal operation or shutdown, and in severe cases, even damaging the variable-frequency power supply.
