Using inverters can, on one hand, improve labor productivity, enhance product quality, and achieve equipment automation. On the other hand, enterprises can effectively save energy and reduce costs in the production process. With the rapid development of China's social economy, both enterprises and the country will pay more attention to the relationship between economy, environment, and energy. Inverters can improve processes, efficiently save electricity, and thus significantly mitigate environmental pollution. Therefore, as a power unit for driving, inverters have broad application prospects.

1. Steps for Selecting Low-Voltage Inverters

It mainly consists of seven steps: (1) Determine the working mode, size, and load type of the equipment; (2) Define the process, functional standards, and control requirements of the equipment; (3) Clarify the system in terms of I/O interfaces, communication interfaces, and assembly modes; (4) Summarize all performance standards and requirements; (5) Based on the summary, conduct direct bidding or technical consultation; (6) Conduct a comprehensive comparison of lifespan, price, performance, and service; (7) Clearly define the model, specifications, brand, and supplier of the inverter.

2. Methods for Selecting Low-Voltage Inverters

For conventional operation of drive control systems, making wise choices regarding general-purpose inverters is crucial. First, determine the ultimate goal of using the general-purpose inverter based on the speed range, speed response, type, starting torque, and control accuracy required by the production machinery. Fully analyze the characteristics of the load driven by the inverter to decide which functions should be used to control the system, then select the optimal control form. The selected inverter should not only meet the needs of production technology but also conform to technical and economic standards. Additionally, it is important to fully consider whether there are issues with the production technology standards, efficiency, harmonics, lifespan, power factor, and sales service of the inverter. Furthermore, continuous operation of the inverter requires that its input/output interfaces, communication metrics, and accessories such as DC braking units and reactors are critical.

The selection of general-purpose inverters includes choosing the type and capacity of the inverter. Selection should follow: First, ensure that the main performance meets the needs of the process; second, the cost-performance ratio should be relatively ideal. When selecting the type of general-purpose inverter, start from the load characteristics. For fans and pumps with balanced torque, where the load torque is smaller at lower speeds, ordinary or specialized function-type inverters are generally selected. For constant-torque loads or machines requiring high static speed precision, high-function inverters with torque control capabilities should be chosen. These inverters feature low-speed torque, hard static mechanical characteristics, and are unaffected by load impacts, exhibiting excavator-like performance. To achieve larger speed ranges under constant torque, the size of the inverter must often be increased. For production machinery requiring high precision, good dynamic performance, and fast speed response, such as injection molding machines, papermaking machinery, or steel rolling machines, choose directly torque-controlled or vector-controlled general-purpose inverters.

In terms of volume, general-purpose inverters usually specify parameters such as the power, rated current, and rated capacity of the motor they can be paired with. However, the power and rated capacity of the motors that can be paired with them are typically given according to the specifications of motors produced by the company or country, without clearly expressing the load-carrying capacity of the inverter. Rated current is an important parameter indicating the load-carrying capacity of the inverter. Therefore, when selecting the capacity of the inverter, the primary principle is to ensure that the motor's rated current is less than the inverter's rated current, only referencing the motor's rated power.

Furthermore, before using a specific inverter capacity, it is essential to know the specific setup parameters and operating procedures of the motor and consider the operational characteristics and model of the motor, leaving some margin. For example, the maximum operating current of submersible pump motors is generally higher than that of ordinary motors; for metallurgical enterprises, the maximum limit current of specialized motors is not only higher but can also operate normally under brief periods of intense current. Often, multiple motors are used together in equipment, but during use, the total operating current should not exceed the motor's maximum specified limit current. Additionally, if using ordinary motors without gearboxes, consider increasing the motor's current storage capacity to ensure normal operation. Also, consider that the output of ordinary inverters is unstable, potentially causing varying degrees of damage to the motor. Thus, when using an inverter to supply power to a motor compared to ordinary grid output current, the motor's current flow increases, leading to higher temperatures. Therefore, when using an inverter for power supply, leave some margin to prevent temperature rise and potential motor damage.

3. Comprehensive Consideration of Environmental Factors When Selecting Inverters

(1)Humidity Impact: Inverters should operate in environments where humidity is below 90%, with relative humidity ≤90% and no condensation. High humidity with significant fluctuations can lead to condensation inside the inverter, reducing insulation performance and potentially causing short circuits. If possible, add heaters and desiccants inside the enclosure.

(2)Temperature Impact: Generally, the operating temperature for inverters should be between -10°C and +40°C. If the ambient temperature exceeds 40°C, for every 1°C increase, the inverter's rated power decreases by 5%. For every 10°C increase in ambient temperature, the inverter's lifespan is halved. Proper management of ambient temperature and inverter cooling is essential.

(3)Dust Impact: Avoid installing inverters in environments with metal conductive dust. If conductive dust enters the inverter, it may cause internal short circuits, and severe cases could result in inverter failure. Even non-conductive dust can affect the inverter, as inverters generate heat during power conversion. Typically, inverters use forced air cooling, and excessive dust accumulation on the heatsink can interfere with cooling, reduce output capacity, or cause malfunctions.

(4)Altitude Impact: Inverters installed at altitudes below 1km can deliver their rated power. At altitudes above 1km, output power decreases.

4. Conclusion

In today's era of widespread inverter usage, selecting and applying them presents significant challenges for many engineering technicians, especially within large-scale drive systems. Inverter selection is complex and requires thorough consideration of all details, parameters, and key performance indicators to ensure reliable system operation.

Changsha Sunye Electric Co., Ltd. (established in 2010), and Shenzhen Sunye Electric Co., Ltd. (established in 2002), are national high-tech enterprises integrating R&D, manufacturing, and sales of inverters, industry-specific integrated 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. Each year, significant investment is made in researching new technologies and developing new products, resulting in numerous patents and software copyrights. The company possesses core platform technologies such as construction hoist drivers, high-performance vector inverters, servos, and permanent magnet synchronous motor controls. Medium- and low-voltage inverters and servo drives are widely used in industries such as lifting, 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 manufacturing. Guided by the philosophy of “Innovation, Technology, Strength,” driven by the corporate spirit of “Unity, Progress, Pragmatism, Innovation,” and adhering to the business principle of “Sincerity and Excellence, Mutual Benefit and Coexistence,” the company aims to provide industry-leading products through comprehensive quality management, continuous improvement, and pursuit of zero defects.

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