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The relationship between frequency converter parameters and harmonics and its analysis

  First, the inverter parameter settings:

  The setting parameters of frequency converter are more, each parameter has a certain range of choice, the use of the individual parameters is often encountered due to improper settings, resulting in the frequency converter can not work normally, therefore, the relevant parameters must be set correctly.

  1. Control mode: speed control, PID control, or other means. After the control mode, the control accuracy of the static or dynamic identification.

  2, the lowest operating frequency: the motor running the minimum speed, the motor running at low speed, the heat dissipation performance is poor, the motor is running at a low speed, will cause the motor burned. And at low speed, the current in the cable will also increase, it will lead to cable fever.

  3, the highest operating frequency: the general frequency converter maximum frequency to 60Hz, and some even to 400 Hz, high frequency will make the motor speed operation, this is the ordinary motor, the bearing can not be long time of the super rated speed operation, the motor rotor is able to withstand the centrifugal force.

  4, carrier frequency: the higher the carrier frequency setting of the higher the higher the higher harmonic component, this and the cable's length, the motor heat, the cable heating frequency inverter and other factors are closely related.

  5, the motor parameters: frequency in parameter setting the motor power, current, voltage, speed, maximum frequency, these parameters can be obtained directly from the motor nameplate.

  6, frequency hopping (FH): at a certain frequency, there may happen resonance phenomenon, particularly in the device is relatively high; in the control of the compressor, to avoid the compressor surge point.

  Two, inverter parameter settings

  Function parameters of frequency converter, there are a lot of ten or even more than one hundred parameters for the user to choose. In practical application, it is not necessary to set up and debug each parameter, and the majority of the parameters can be set to the factory setting value.

  1, plus deceleration time

Acceleration time is the output frequency from 0 to the maximum frequency of the required time, deceleration time is the maximum frequency of the time required to fall from 0 to. Usually set the signal to rise and fall to determine the time of acceleration and deceleration. When the motor is accelerated, the rate of rise of the frequency setting is required to prevent over current, and the rate of decline is limited to prevent over voltage.Acceleration time setting requirements: the acceleration current limit in the frequency converter capacity below, does not cause the flow stall and caused by frequency converter tripping; deceleration time setting point is: to prevent the smooth circuit voltage is too large, do not make the regeneration of over-voltage and converter tripping. Add deceleration time can be calculated according to the load, but often take the load and experience to set up a long time, through the starting and stopping the motor to observe whether there is current, over voltage alarm; and then increase the deceleration setting time is gradually shortened, in order to operate without reporting to the principle, repeat the operation several times, can determine the optimal deceleration time.

  2, torque boost

  Also known as torque compensation is to compensate for the motor stator winding resistance caused by low speed when the torque is reduced, and the low frequency range of f/V method. When setting is automatic, it can be automatically promoted to compensate the starting torque, so as to speed up the motor. In the use of manual compensation, according to the load characteristics, especially the starting characteristics of the load, the better curve can be selected by the test. For variable torque load, the output voltage is too high, and the phenomenon of waste electrical energy is high, even when the electric power is high, and the electric current is large, and the speed is not.

Keywords:Active power filter,Active filter, Power quality,Harmonic control,APF
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