How to set parameters of the inverter?
Inverter parameter setting (1)
There are many setting parameters of the inverter, each parameter has a certain range of selection. In use, it is often encountered that the inverter cannot work normally due to improper setting of individual parameters. Therefore, the relevant parameters must be correctly set.
1. Control mode: speed control, torque control, PID control or other methods. After the control method is adopted, static or dynamic identification is generally performed according to the control precision.
2, the lowest operating frequency: that is, the minimum speed of the motor running, when the motor runs at low speed, its heat dissipation performance is very poor, the motor running at low speed for a long time, will cause the motor to burn. At low speeds, the current in the cable also increases, which can also cause the cable to heat up.
3, the highest operating frequency: the general frequency of the inverter to 60Hz, and some even to 400 Hz, high frequency will make the motor run at high speed, this for ordinary motors, its bearings can not run for a long time at the super rated speed, the motor Whether the rotor can withstand such centrifugal force.
4, carrier frequency: the higher the carrier frequency setting, the higher the harmonic component, which is closely related to the cable length, motor heating, cable heating inverter heating and other factors.
5. Motor parameters: The inverter sets the power, current, voltage, speed and maximum frequency of the motor in the parameters. These parameters can be directly obtained from the motor nameplate.
6. Frequency hopping: At a certain frequency point, resonance may occur, especially when the whole device is relatively high; when controlling the compressor, the surge point of the compressor should be avoided.
Inverter parameter setting (2)
There are many function parameters of the inverter, generally there are dozens or even hundreds of parameters for the user to choose. In practical applications, it is not necessary to set and debug each parameter, and most of them only need to adopt the factory setting value.
First, acceleration and deceleration time
The acceleration time is the time required for the output frequency to rise from 0 to the maximum frequency, and the deceleration time is the time required to fall from the maximum frequency to 0. The acceleration and deceleration time is usually determined by the frequency setting signal rising and falling. When the motor is accelerating, the rate of increase of the frequency setting must be limited to prevent overcurrent, and when decelerating, the rate of decrease is limited to prevent overvoltage.
Acceleration time setting requirement: Limit the acceleration current below the overcurrent capacity of the inverter, and do not cause the inverter to trip due to the over-speed. The deceleration time setting point is: prevent the smoothing circuit voltage from being too large, and the regenerative overvoltage stall is not caused. Let the frequency converter trip. The acceleration/deceleration time can be calculated according to the load. However, in the commissioning, the long acceleration/deceleration time is set according to the load and experience. The motor is observed by the start and stop motors to see if there is overcurrent or overvoltage alarm. Then the acceleration/deceleration setting time is gradually Shorten, the principle of no alarm occurs during operation, and repeat the operation several times to determine the optimal acceleration and deceleration time.
Second, the torque boost
Also called torque compensation, it is a method to increase the low frequency range f/V to compensate for the torque reduction at low speed caused by the stator winding resistance of the motor. When set to automatic, the voltage during acceleration can be automatically increased to compensate for the starting torque, so that the motor accelerates smoothly. If manual compensation is used, a better curve can be selected by experiment depending on the load characteristics, especially the starting characteristics of the load. For variable torque loads, if the selection is improper, the output voltage will be too high at low speed, and the phenomenon of wasting electric energy may even occur when the motor is loaded with load and the current is not high.
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