High-voltage inverter fault handling method - Solutions - Huaqiang Electronic Network

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The high-voltage inverter is equipped with a highly intelligent computing system and a comprehensive fault detection circuit. It provides accurate fault positioning and clear instructions on the main control interface. In practical applications, common faults are typically categorized into control channel anomalies, IGBT overcurrents, overvoltage issues, and similar problems. Below are some typical faults along with their causes and solutions.

1. Control Channel Abnormal Fault

A control channel abnormality is usually caused by fiber-optic communication between the PWM board and the power unit board. Common reasons include:

• Poor contact or disconnection of the fiber connector
• Dust accumulation inside the fiber signal transmitter/receiver
• Fiber breakage
• Damage to the optical fiber communication control board

When a fiber issue occurs, the first step is to determine whether the problem lies with the power unit or the controller side. By swapping the fiber corresponding to one power unit in the same phase on the controller’s fiber board, you can identify the faulty component. If the fault remains in the original position on the monitoring interface, it indicates the fiber board is damaged. Otherwise, the power unit may be at fault. In such cases, consider replacing or repairing the affected unit.

2. IGBT Overcurrent Fault – Causes and Solutions

The IGBT is a critical power device in high-voltage inverters. Due to its high-power nature, it can suffer from locking phenomena when an overcurrent occurs. To enhance system reliability, various preventive measures are taken. Common causes of IGBT overcurrent faults include:

• Short circuit on the inverter output
• IGBT breakdown in the power unit
• Damage to the drive detection circuit
• Interference in the detection circuit

To diagnose the issue, locate the corresponding module based on the fault display on the monitoring interface and inspect the IGBT for damage. To test, connect the multimeter's black probe to the positive V+ and red probes to U and V. The diode reading should show approximately 0.4V. Reversing the test should result in infinity. Repeat the process with the red probe connected to V- and ensure the same results. If not, the IGBT is likely damaged and needs replacement.

3. Overvoltage Fault – Causes and Solutions

Overvoltage issues typically originate from the input side of the power supply. Under normal conditions, grid voltage fluctuations are within ±10% of the rated voltage. However, in special situations, the DC bus voltage may rise due to higher input voltages, triggering overvoltage protection. To prevent this, adjust the transformer tap if the field voltage is consistently high. Additionally, adding an absorption device on the input side can help reduce overvoltage effects on the inverter.