Fuji inverter's common faults and repairs - Solutions - Huaqiang

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For those who use inverters, Fuji is a brand that many are familiar with. It has dominated half of the Chinese inverter market due to its user-friendly interface and excellent cost-performance ratio. However, as time passes, these widely used inverters have entered a high-risk phase for failures. When an inverter malfunctions, how do technicians identify and resolve the issue? This is a critical challenge faced by daily operators. In this article, we will explore common faults and troubleshooting solutions for Fuji inverters, aiming to provide valuable insights for users.

Over nearly two decades, Fuji inverters have evolved significantly in design, circuit board technology, and component integration. From the early 2 series to the current 11 series, there are various models such as the general-purpose G series, P series for fans and pumps, E series for basic applications, K series, and the ultra-compact C series tailored for different load characteristics. Additionally, the VG3 inverter is specifically designed for elevators. High-power models like the G7 and P7 (above 30kW) also come with optional cards including dry contact relay output cards, digital/analog interface cards, PG feedback cards, and dual motor synchronous cards. These features ensure that Fuji inverters meet diverse user needs and form the foundation of their development.

OC1, OC2, OC3 Faults

The OC1, OC2, and OC3 errors are among the most common issues encountered during the repair of Fuji inverters. These indicate overcurrent conditions during acceleration, deceleration, or constant speed. The main causes include:

  1. Short Acceleration Time: This is the most frequent cause of overcurrent. Adjusting the acceleration and deceleration times based on the load can help eliminate the issue.
  2. High-Power Transistor Damage: As semiconductor technology has advanced, Fuji inverters have transitioned from GTR modules to IGBT and IPM modules. Damage to these components can result from short circuits, excessive load currents, or large fluctuations in load, leading to overcurrent alarms.
  3. Drive Circuit Failure: The drive circuit, often using components like PC922 or PC923, can fail due to missing phases or unbalanced three-phase outputs, causing overcurrent problems.
  4. Detection Circuit Issues: Hall sensors used for current detection may drift due to environmental factors like temperature and humidity, triggering false overcurrent alarms.

Switching Power Supply Failure

A clear sign of a faulty switching power supply is when the inverter fails to display any power. For example, the Fuji G5S uses a two-stage power supply system. Common issues include switch tube breakdown, pulse transformer damage, secondary rectifier diode failure, or aging capacitors that lose their filtering ability. The G9S model uses a specialized waveform chip, which can be difficult to replace due to limited availability, making repairs more challenging.

Rectifier Bridge Damage

Damage to the rectifier bridge is another frequent fault. The G7S model uses a thyristor-based module instead of a traditional bridge, improving reliability. The G9S model integrates the thyristor and switch transistor into one unit. If the rectifier bridge fails, it's essential to check peripheral equipment before powering up the system.

LV and OV Faults

Undervoltage (LV) and overvoltage (OV) faults are also common. These can be caused by unstable power input or issues within the inverter’s detection circuit. For example, the G5S uses a custom thick-film voltage detection board, while the G7S and G9S models sample the DC bus directly for accurate readings.

Other common error codes related to the motherboard include Err, Er1, Er7, Er3, and others. While the basic principles of inverters are similar, the implementation details vary, requiring hands-on experience and continuous learning. By refining our understanding through practice, we can detect and solve problems more efficiently. For those involved in inverter maintenance, this knowledge is invaluable. Shanghai Sanguang Digital Technology Co., Ltd. stands out in the industry with strong technical support and partnerships with companies like Hong Kong Hengfa Technology Co., Ltd., offering comprehensive solutions for integrated circuits, sensors, and electronic components.

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