13 commonly used parameters of VFD, incorrect settings will cause the frequency converter to not work properly?

The frequency converter has many setting parameters, and each parameter has a certain selection range. It is often encountered in use that the frequency converter cannot work properly due to improper setting of individual parameters. Therefore, the relevant parameters must be set correctly.

01 Control mode

That is, speed control, torque control, PID control or other methods. After adopting the control mode, static or dynamic identification is generally required according to the control accuracy.

02 Minimum operating frequency

That is, the minimum speed of the motor. When the motor runs at a low speed, its heat dissipation performance is very poor. If the motor runs at a low speed for a long time, it will cause the motor to burn out. Moreover, at low speed, the current in its cable will also increase, which will also cause the cable to heat up.

03 Maximum operating frequency

The maximum frequency of a general frequency converter is 60Hz, and some even reach 2000 Hz. High frequency will make the motor run at high speed. For ordinary motors, their bearings cannot run at over-rated speed for a long time. Whether the rotor of the motor can withstand such centrifugal force.

04 Carrier frequency

The higher the carrier frequency is set, the greater the high-order harmonic component is. This is closely related to factors such as the length of the cable, motor heating, cable heating, and inverter heating.

05 Motor parameters

The inverter sets the motor power, current, voltage, speed, and maximum frequency in the parameters. These parameters can be directly obtained from the motor nameplate.

06 Frequency hopping

At a certain frequency point, resonance may occur, especially when the entire device is relatively high; when controlling the compressor, the vibration point of the compressor should be avoided.

07 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 drop from the maximum frequency to 0. The acceleration and deceleration time is usually determined by the rise and fall of the frequency setting signal. When the motor accelerates, the frequency setting rise rate must be limited to prevent overcurrent, and when decelerating, the fall rate must be limited to prevent overvoltage.

08 Torque boost

Also called torque compensation, it is a method of increasing 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 can accelerate smoothly. If manual compensation is used, according to the load characteristics, especially the starting characteristics of the load, the best curve can be selected through experiments.

09 Electronic thermal overload protection

This function is set to protect the motor from overheating. It is the CPU in the inverter that calculates the temperature rise of the motor according to the operating current value and frequency, thereby performing overheat protection.

10 Frequency limit

The upper and lower limits of the inverter output frequency. Frequency limit is a protection function to prevent misoperation or failure of the external frequency setting signal source, which causes the output frequency to be too high or too low, so as to prevent damage to the equipment. It can be set according to the actual situation in the application. This function can also be used for speed limiting.

11 Deviation frequency

Its purpose is that when the frequency is set by an external analog signal (voltage or current), this function can be used to adjust the output frequency when the frequency setting signal is the lowest. When the frequency setting signal of some inverters is 0%, the deviation value can be applied in the range of 0 to fmax, and some inverters can also set the bias polarity. For example, when the frequency setting signal is 0% during debugging, the inverter output frequency is not 0Hz, but xHz. At this time, setting the bias frequency to negative xHz can make the inverter output frequency 0Hz.

12 Frequency setting signal gain

This function is only valid when the frequency is set by an external analog signal. It is used to make up for the inconsistency between the external setting signal voltage and the voltage inside the inverter (+10v); at the same time, it is convenient to select the analog setting signal voltage. When setting, when the analog input signal is the maximum (such as 10v, 5v or 20mA), find the frequency percentage of the output f/V graph and set it as a parameter; if the external setting signal is 0~5v, if the inverter output frequency is 0~50Hz, then set the gain signal to 200%

13 Torque limit

There are two types: driving torque limit and braking torque limit. It calculates the torque through the CPU based on the inverter output voltage and current values, which can significantly improve the impact load recovery characteristics during acceleration, deceleration and constant speed operation. The torque limit function enables automatic acceleration and deceleration control. Assuming that the acceleration and deceleration time is less than the load inertia time, it can also ensure that the motor automatically accelerates and decelerates according to the torque setting value.

The driving torque function provides powerful starting torque. During steady-state operation, the torque function will control the motor slip and limit the motor torque to the maximum set value. When the load torque suddenly increases, even When the acceleration time is set too short, it will not cause the inverter to trip. exist

The smaller the braking torque setting value, the greater the braking force, which is suitable for situations of rapid acceleration and deceleration. If the braking torque setting value is set too high, an overvoltage alarm will occur.