Common parameters of air compressor inverter

Common parameters of air compressor inverter

There are many setting parameters of the air compressor inverter, and each parameter has a certain adjustment range. In the application, it is often encountered that the air compressor inverter cannot operate normally due to the improper setting of a single parameter. Therefore, it is necessary to Make accurate settings for the relevant parameters.

　　1 Manipulation method

　　 means speed control, torque control, PID control or other methods. After adopting the control method, static or dynamic identification is usually carried out according to the control accuracy.

　　2 Minimum operating frequency

　　 is the minimum rotation speed of the motor. When the motor is operated at a low rotation speed, its heat dissipation function is very poor. If the motor is operated at a low rotation speed for a long time, it will cause the motor to burn. And at low speeds, the current in the cable will increase, which will also cause the cable to heat up.

　　3 Maximum operating frequency

　　 The maximum frequency of the general air compressor inverter is up to 60Hz, and some even 400Hz. The high frequency will make the motor operate at high speed. For the general motor, the bearing cannot operate at an extra speed for a long time. This needs to consider whether the rotor of the motor can accept such a strong centrifugal force.

　　4 carrier frequency

　　 The higher the carrier frequency setting, the greater the weight of the higher harmonics, which is closely related to the length of the cable, the heating of the motor, the heating of the cable, the heating of the air compressor and the inverter.

　　5 Motor parameters

　　 The air compressor 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 all the devices are relatively high; when operating the centrifugal compressor, avoid the surge point of the centrifugal compressor.

　　7 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 for the output frequency to decrease from the maximum frequency to 0. Usually the frequency setting signal rises and falls to determine the acceleration and deceleration time. When the motor is speeding up, the rate of increase of the frequency setting must be restricted to avoid overcurrent, and when the motor is decelerating, the rate of decrease is restricted to avoid overvoltage.

Speed-up time setting request: constrain the speed-up current below the over-current capacity of the air compressor inverter, so as not to cause excessive stall speed and cause the air compressor inverter to trip; the key to setting the deceleration time is to avoid excessive slippage circuit voltage. Stall the regeneration overvoltage and trip the air compressor inverter. The acceleration and deceleration time can be calculated according to the load, but in debugging, it is often adopted to set a longer acceleration and deceleration time according to the load and experience, and observe whether there is an overcurrent and overvoltage alarm by starting and stopping the motor; then gradually set the acceleration and deceleration time Shorten, based on the principle that no alarm occurs during operation, repeat the operation several times to determine the best acceleration and deceleration time.

　　 8 torque increase

　　 is also called torque compensation, which is a method of increasing the low frequency scale f/V to compensate for the torque drop at low speed caused by the resistance of the motor stator winding. When set to active, the voltage during acceleration can be actively increased to compensate for the starting torque, so that the motor can accelerate smoothly. If manual compensation is selected, a better curve can be selected through experiments based on load characteristics, especially load starting characteristics. For variable torque loads, if the adjustment is not proper, the output voltage at low speed will be too high, which will waste the electric energy, and even the current will be large when the motor starts with load, but the speed will not go up.

　　 9 electronic thermal overload maintenance

　　 This function is set to maintain the motor overheating. It is the CPU in the air compressor inverter to calculate the temperature rise of the motor based on the operating current value and frequency, and then perform overheating maintenance. This function is only suitable for "one tow one" occasion, and when "one tow many", thermal relay should be installed on each motor.

　　Electronic thermal maintenance setting value (%)=[Extra motor current (A)/Extra output current of air compressor inverter (A)]×100%.

　　10 frequency constraint

　　 is the upper and lower limit value of the output frequency of the air compressor inverter. Frequency restriction is a maintenance function to avoid misoperation or failure of the external frequency setting signal source, which may cause the output frequency to be too high or too low 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. For some belt conveyors, because there are not too many materials to be transported, in order to reduce the wear of the machinery and belts, an air compressor inverter can be used to drive, and the upper limit frequency of the air compressor inverter can be set. Set to a certain frequency value, so that the belt conveyor can operate at a fixed, lower operating speed.

　　11 Bias frequency

　　Some are also called error frequency or frequency error setting. Its use is when the frequency is guarded by an external imitating signal (voltage or current), this function can be used to adjust the unevenness of the output frequency when the frequency setting signal is the lowest. When the frequency setting signal of some air compressor inverters is 0%, the error value can be applied to the scale of 0～fmax, and some air compressor inverters can also set the bias polarity. For example, when the frequency setting signal is 0% during debugging, the output frequency of the air compressor inverter is not 0Hz, but xHz, then set the bias frequency to negative xHz to make the air compressor inverter output The frequency is 0 Hz.

　　12 frequency setting signal gain

　　This function is only useful when the frequency is set with an external analog signal. It is used to compensate for the inconsistency between the external setting signal voltage and the internal voltage of the air compressor inverter (+10v); when the imitated input signal is z*large (such as 10v, 5v or 20mA), the output f/V can be calculated The frequency percentage of the graph can be set as a parameter; for example, when the external setting signal is 0～5v, if the output frequency of the air compressor inverter is 0～50Hz, then set the gain signal to 200%. .

　　13 Torque constraint

　　 can be two kinds of driving torque constraint and braking torque constraint. It is based on the output voltage and current value of the air compressor inverter, and the CPU performs torque calculation, which can significantly improve the impact load recovery characteristics during acceleration, deceleration and constant speed operation. The torque constraint function can complete active 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 actively accelerates and decelerates according to the torque setting.

The driving torque function provides a strong starting torque. During steady-state operation, the torque function will control the motor slip and constrain the motor torque within the maximum set value. When the load torque increases suddenly, even If the acceleration time is set too short, it will not cause the air compressor inverter to trip. When the acceleration time is set too short, the motor torque will not exceed the maximum set value. Large driving torque is beneficial to starting, so it is better to set it to 80-100%.

　　 The smaller the braking torque setting value, the greater the braking force. It is suitable for rapid acceleration and deceleration occasions. If the braking torque setting value is set too high, an overvoltage alarm will appear. If the braking torque is set to 0%, the total amount of regeneration added to the main capacitor can be close to 0, and then when the motor is decelerating, it can decelerate to a stop without using a braking resistor without tripping. However, on some loads, such as when the braking torque is set to 0%, there will be a short idling phenomenon when decelerating, resulting in repeated starting of the air compressor inverter, the current will fluctuate greatly, and the air compressor will be frequency-changed in severe conditions. It should be noted that the device has tripped.