Inverter capacity selection based on motor power based on misunderstanding analysis

Inverter capacity selection based on motor power based on misunderstanding analysis

The power of the inverter refers to the power of the 4-pole AC asynchronous motor to which it is applied.

Due to the same capacity motor, the number of poles is different and the rated current of the motor is different. As the number of poles of the motor increases, the rated current of the motor increases. The capacity selection of the inverter cannot be based on the rated motor power. At the same time, for the transformation project that did not use the inverter, the capacity selection of the inverter can not be based on the rated current of the motor. This is because the capacity selection of the motor should take into account factors such as maximum load, richness factor, motor specifications, etc., and often have a large margin, and industrial motors often operate at 50% to 60% of rated load. If the capacity of the inverter is selected based on the rated current of the motor, the margin is too large, resulting in economic waste, and the reliability is not improved.

For squirrel-cage motors, the capacity of the inverter should be selected based on the principle that the rated current of the inverter is greater than or equal to 1.1 times the maximum normal operating current of the motor, which can save money. For heavy-duty starting, high temperature environment, wound motor, synchronous motor, etc., the capacity of the inverter should be appropriately increased.

For the design of the inverter from the beginning, the choice of the inverter capacity is based on the rated current of the motor. This is because the inverter capacity cannot be selected in actual operation at this time. Of course, in order to reduce investment, in some occasions, the capacity of the inverter can be determined first. After the equipment is actually running for a period of time, it is selected according to the actual current. For the transformation project that did not use the inverter, the capacity of the inverter can be greatly reduced according to the actual working conditions.