To solve the problem of anti-interference is the key to the application of inverter!
The frequency converter is a device that converts the power frequency power supply into the frequency conversion power supply, which is between the power frequency power supply and the electrical equipment. Inverter is a typical power electronic device, its hardware core is power electronic components and microprocessor chip. The power electronic components, the input and output copper bars and the front-end control components constitute the power unit, which belongs to the strong current or power module; The main control board, the input and output module and the display control module with the microprocessor chip as the core constitute the control unit, which belongs to the weak current or control module; The function expansion connector and external components constitute the expansion unit, which adapts to various working characteristics.
When the inverter is directly connected to the power grid, the grid capacity, grid voltage level and voltage deviation should be fully evaluated; When indirectly connected to the power grid through the transformer, the transformer capacity, output voltage value and its deviation. Inverter output contains rich harmonic content, which not only has different degrees of influence on the motor, but also in turn pollutes the power supply and interferes with other electrical equipment on the grid.
When the power compensation device is connected in the distribution transformer, the waveform of the input current of the inverter will be distorted, which will degrade the performance of the inverter. When the inverter is running, additional heating factors will be added, resulting in the power output of the inverter not reaching the normal level.
In order to obtain ideal electromagnetic compatibility effect, it is better to use iron shell for inverter protection body, steel pipe for output cable for necessary shielding, and shielding and isolation measures are also implemented between power unit and control unit. If necessary, it can be equipped with input filter or zero sequence inductor to cut off the reverse transmission channel of the clutter component of the inverter as far as possible.
In the process of practical application, it can be found that the quality of the current matching motor inverter is uneven, which leads to the poor fit between the inverter and the motor, resulting in two adverse effects: first, the poor performance level of the motor in the operation process, and even lead to malignant quality accidents such as poor performance level and short service life of the motor; 2、 During the performance test of variable frequency motor, the measured parameters are not stable, which seriously interferes with the test of adjacent motor.