The temperature protection function of an inverter is an indispensable condition for ensuring stable operation. As an essential protective feature, today we will focus on "over-temperature protection" and discuss several common faults related to this function and their solutions.

1. Inverter Over-Temperature Protection and Its Necessity
The temperature protection function of an inverter is crucial for ensuring its stable operation. Power devices in the main circuit of an inverter, such as rectifier bridges and inverter bridges, are semiconductor power devices that cannot exceed their allowable operating range due to limitations of their working temperature characteristics. Moreover, the electronic circuits of the inverter must not be too hot. If the inverter overheats, it may lead to reduced overall performance, accelerated aging of components, or even explosions, making temperature protection necessary.
2. Temperature Detection in Inverters
(1) Typically, inverters detect intake air temperature, which can be understood as ambient temperature; the temperatures of heat sinks near the rectifier bridge and the inverter bridge vary depending on power levels.
(2) During the initial R&D phase of the inverter, thermal balance checks are performed to ensure that heat generation under rated load balances with the dissipation capacity of the inverter, meaning the inverter should not overheat under normal operating conditions.
3. Excessive Temperature Due to Improper Design and Selection
① Mismatch between inverter capacity and the driven motor's power leads to high operating currents, ultimately triggering over-temperature protection.
② Insufficient selection margin for the inverter, without fully considering load fluctuations and overload repetition cycles.
③ Using inverters at high altitudes without adequately addressing capacity reduction issues. The thin air at high altitudes results in poor cooling efficiency. (Of course, higher altitude temperatures are lower than those at low altitudes, which benefits inverter cooling.)
④ Long-term low-frequency operation increases switch losses in the inverter, leading to overheating. Increasing the operating frequency and transmission ratio can mitigate this issue.
⑤ For environments with high ambient temperatures, consider installing air conditioning within the inverter cabinet or throughout the electronic control room to enhance cooling.
4. Over-Temperature Issues Caused by the Inverter Itself
① Abnormal temperature detection circuits trigger over-temperature alarms.
② Damaged temperature sensors cause false over-temperature readings.
③ Failure of the built-in cooling fan or abnormal DC24V fan power supply leads to overheating.
④ For high-power inverters, improper voltage selection for the cooling fan transformer results in insufficient fan speed. Additionally, blown fuses in the cooling fan power transformers can prevent fans from turning.
5. Excessive Temperature Due to Poor Cabinet Design
① Insufficient consideration given to installation space within the cabinet. Adequate clearance must be reserved according to the hardware manual.
② Inadequate ventilation in the inverter cabinet prevents effective heat dissipation.
③ Poorly designed inverter cabinets often have cold air intakes at the bottom and hot air outlets at the top. Multi-level stacking of inverters within a cabinet can obstruct airflow, leading to overheating.
6. Over-Temperature Due to Improper Usage
① High concentrations of oil mist and dust in the air around the inverter accumulate on the heat sink, hindering heat dissipation. Install filter cotton at the inverter cabinet’s intake.
② Installation of the inverter cabinet above cable trenches without proper sealing allows dust and debris into the cabinet, blocking cooling ducts and causing overheating.
③ Incorrect installation orientation of the inverter can also lead to overheating. Vertical installation is recommended for optimal heat dissipation.
④ Setting the switching frequency too high (P1800 parameter) increases switch losses and may result in overheating.
Sunye Electric Co., Ltd. (Changsha Sunye Electric Co., Ltd. was established in 2010; Shenzhen Sunye Electric Co., Ltd. was established in 2002) is a national high-tech enterprise integrating R&D, manufacturing, and sales of inverters, industry-specific all-in-one machines, servo drives, and new energy products.
Sunye Electric owns independent intellectual property rights. Its products have passed inspections and certifications by national authoritative institutions and have obtained multiple software copyrights and IP certificates. It invests heavily every year in researching new technologies and developing new products, with many patents and software copyrights granted. The company possesses core platform technologies such as construction hoist drivers, high-performance vector inverters, servos, and permanent magnet synchronous motor controls. Its low- and medium-voltage inverters and servo drives are widely used in industries such as lifting equipment, stone processing, HVAC, machine tools, metal products, wire and cable, plastics, printing and packaging, textile and chemical fibers, building materials, metallurgy, coal mining, municipal services, and automotive applications. Guided by the philosophy of "innovation, technology, and strength," and driven by the corporate spirit of "unity, progress, pragmatism, and innovation," the company adheres to the business principle of "honesty and excellence, mutual benefit and coexistence." With a quality policy of "implementing total quality management and continuous improvement to pursue zero defects," Sunye Electric is committed to providing premium products to customers across various industries.
Address: Sunye Electric Industrial Park, No. 669 Xinsheng Road, High-Tech Zone, Changsha City
Tel/Fax: 0731-89932666 0731-89932688
Business Phone: 400-0755-731
Technical Support: 400-0755-731