Frequency converter selection(1)
The type of frequency converter is selected. According to the type of production machinery, speed range, static speed accuracy and starting torque, the type of control mode is decided to choose the most appropriate frequency converter. What is called appropriateness is that it should be easy to use and economical to meet the basic conditions and requirements of technology and production.
1. Motor and frequency converter need to be controlled.
1) Number of poles of motor. General motor number is more appropriate, otherwise the converter capacity should be appropriately increased.
2) Torque characteristics, critical torque and acceleration torque. In the case of the same motor power, compared to the high overload torque mode, the converter specification can be reduced to select.
3) Electromagnetic compatibility. In order to reduce the interference of main power supply, the reactor can be added in the input circuit of intermediate circuit or frequency converter, or the isolation transformer can be installed. Generally, when the distance between the motor and the frequency converter is more than 50m, reactor, filter or shielding protective cable should be inserted among them.
3. Main power supply
1) Power supply voltage and fluctuation. Special attention should be paid to the adaption of low voltage protection setting value of frequency converter, because low voltage of power grid is more likely in practical use.
2) Frequency fluctuation and harmonic interference of main power supply. The interference in this aspect will increase the heat loss of the converter system, resulting in increased noise and decreased output.
3) The power consumption of frequency converter and motor when working. When designing the main power supply of the system, the power consumption factors of both should be taken into account.