Whether the selection of a Variable Frequency Drive (VFD) is scientific or not is crucial to the normal operation of the frequency conversion system. Many beginners lack sufficient understanding of how to properly select general-purpose VFDs, or even if they know the method, they are unsure whether the selected model is correct. Next, we will reveal the secrets for you.

When selecting a VFD, the first consideration should be the AC motor. In most cases, the motor is determined first before choosing the VFD. In principle, the VFD model should be selected based on the actual current of the motor during long-term operation, rather than according to the power rating on the motor's nameplate.

The second factor in VFD selection is the type of load. The equipment driven by VFD systems can generally be divided into three types: constant torque loads, constant power loads, and fan/pump loads. Different types of loads require different VFD models.
1. Constant Power Load
During operation, the power of the load remains constant. Examples include machine tools, cutting machines, paper-making machines, etc.
Example: A marble cutting machine VFD system is a constant power load with large inertia. The VFD model selected is an AMB300 G-type unit of the same power rating, plus a braking unit and braking resistor.
2. Constant Torque Load
Equipment with constant torque load requires VFDs with high low-frequency torque and fast dynamic response.
Example: A bucket wheel excavator VFD system on a sand dredging ship is a constant torque load with dual motors and long periods of overload. Therefore, the VFD selected is an AMB300 G-type unit two sizes larger than required, operating in parallel with AC input reactors installed.
3. Fan and Pump Loads
These types of applications are ideal for VFD control. They do not require advanced VFD functions, but using VFDs results in significant energy savings.
Example: A large centralized heating system in Northeast China uses VFDs for its鼓风机 (blower fans), 引风机 (induced draft fans – centrifugal fans). These VFDs are selected as P-type units of the same power rating. For 循环泵 (circulating pumps), G-type VFDs of the same power rating are used. For 皮带机 (belt conveyors / 输煤机 - coal conveyors), G-type VFDs one size larger are selected. For 除渣机 (slag removal machines), G-type VFDs one size larger are also used. For 破碎机 (coal crushers), G-type VFDs one or two sizes larger are selected.
Changsha Sunye Electric Co., Ltd. (established in 2010) and Shenzhen Sunye Electric Co., Ltd. (established in 2002) are national high-tech enterprises specializing in R&D, manufacturing, and sales of inverters, industry-specific integrated machines, servo drives, and new energy products.
Sunye Electric owns independent intellectual property rights, with products certified by national authorities and multiple software copyrights and IP certificates. Significant investment is made annually in new technologies and product development, with numerous patents and software copyrights approved. 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