Selecting a VFD motor is a discipline that requires comprehensive consideration of technical parameters, application scenarios, and cost-effectiveness. The following provides a systematic explanation of key selection points from a professional perspective to assist enterprises and technical personnel in making scientific decisions.
• Constant torque loads (e.g., conveyors, compressors) require models with an overload capacity exceeding 150%. The rated power should be ≥ 1.2 times the actual required power.
• Variable torque loads (e.g., fans, industrial pumps) can utilize dedicated energy-saving VFD motors, where the power matching coefficient can be reduced to 1.05-1.1.
• Impact loads require motors with high flywheel torque, and H-class insulation is recommended.
• During speed regulation below base frequency, standard motors must ensure torque at 20Hz is no less than 90% of the rated value.
• For high-speed applications (>100Hz), dedicated high-frequency motors must be selected, requiring the use of ceramic hybrid bearings.
• IP54 is suitable for ordinary industrial environments.
• Protection ratings of IP65 and above require special sealing structures, increasing cost by approximately 30% but extending service life by 2-3 times.
• For explosive atmospheres, choose Ex dⅡBT4 or Ex deⅡCT6 ratings.
• Self-cooled (IC411) is suitable for applications <55kW.
• Forced air cooling (IC416) is more effective in enclosed spaces.
• Water-cooled (IC81W) is suitable for high-power, densely installed applications.
• IE3 electric motors are 15-20% more expensive than IE2 motors but can achieve 10-15% annual energy savings.
• For applications with continuous operation >4000 hours/year, IE4 super premium efficiency motors are recommended.
• Dedicated VFD motors improve efficiency by 3-5% compared to standard motor + VFD combinations.
• Initial procurement cost accounts for approximately 30%.
• Electricity costs over 5 years account for 60-70%.
• Maintenance costs must consider bearing replacement cycles (typically 20,000-40,000 hours).
• Select Permanent Magnet Synchronous Motors (PMSM) with dynamic response times <5ms.
• Encoder resolution should be at least 17-bit.
• It is recommended to configure a braking resistor unit.
• Employing common DC bus technology can save 8-12% in energy.
• Circulation current suppression devices are required.
• Standardizing motor models is recommended to reduce spare parts inventory.
1. International brands (e.g., Siemens, ABB) command a premium of about 30-50%, but their Mean Time Between Failures (MTBF) can reach 100,000 hours.
2. High-quality domestic brands (e.g., Inovance, PJM) offer excellent cost-performance ratios and faster technical support response.
3. Key Document Verification:
• Obtain type test reports.
• Secure bearing life commitment letters.
• Request energy efficiency certification documents.
During the final selection decision, establish a scoring matrix to conduct a weighted evaluation of all 16 key indicators mentioned. Prototype testing is strongly advised, involving at least 72 hours of continuous operation to verify parameters such as temperature rise and vibration. The final selected solution should incorporate a 15-20% design margin to accommodate operational fluctuations.
