Panasonic inverter common fault handling - Solutions - Huaqiang Electronic Network

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(1) Panasonic Inverter Power-On Without Display

During the maintenance of the DV707 series inverter, one common fault is when the inverter powers on but there's no display. After ruling out external power supply and display issues, the problem often lies in the switching power supply. One of the most vulnerable components is the pulse transformer. Due to factors like high-frequency magnetic materials, load capacity, and short-circuit overcurrent protection design, the primary winding of the pulse transformer is prone to burning out. The structure of this transformer differs from standard step-up or step-down transformers, making it difficult to disassemble. Sometimes, after removal, the magnetic core may crack, creating a gap that disrupts the closed magnetic field, leading to failure. In such cases, replacing the pulse transformer is usually the best solution.

Additionally, the switching power supply design of the DV707 series inverter is unique. It uses an integrated block model MA2810, which combines the switching transistor and clamp regulator into one unit. This reduces the peripheral circuitry, but the MA2810 is still susceptible to damage during repairs.

(2) Panasonic Inverter Module Damage

In the VF-7F series inverter, the inverter module can sometimes be damaged. A typical symptom is when the inverter suddenly loses power during normal operation and fails to start the motor upon re-powering. Upon inspection, the main cause is often related to the inverter continuing to receive a running command after a power failure. At this point, the intermediate DC voltage drops rapidly due to the motor’s load and internal consumption, causing the PWM signal to become unstable and potentially damaging the power module. In these cases, the drive circuit is typically not affected. Replacing the inverter module usually restores normal operation. To prevent this issue, it's advisable to implement control circuit measures that block the inverter output during a power cut.

(3) Panasonic Inverter Drive Circuit Failure

During the maintenance of DV707 series inverters, both the inverter module and the drive circuit can be damaged. A common issue in the drive circuit is the absence of a negative voltage. The DV707 series uses Fuji PIM modules, which are IGBT-based. These transistors require a negative voltage to turn off properly. Without it, the IGBT may misfire, leading to conduction errors. Negative voltage is typically generated by a Zener diode, which is the most common point of failure. Once replaced, the drive waveform should return to normal.

(4) Panasonic Inverter LV Failure

LV failure is another frequent issue encountered during inverter maintenance, especially in the DV700 series. After eliminating external power supply problems, the issue is likely related to the detection circuit. The step-down resistor samples the signal, which is then isolated by an optocoupler before being sent to the main control board. Both the resistor and the optocoupler could be damaged. Replacing them usually restores normal function.