Inverter setting parameters are numerous, each parameter has a certain selection range, the use of individual parameters are often encountered due to improper setting, resulting in the inverter can not work properly. Therefore, inverter commissioning starts from the correct setting of inverter parameters.
In this article, we will summarize the basic inverter parameter setting method for your reference. These parameters include control mode, minimum operating frequency, maximum operating frequency, carrier frequency, motor parameters, frequency hopping, acceleration and deceleration time, torque boost, electronic thermal overload protection, frequency limitation, bias frequency, frequency setting signal gain, torque limitation, acceleration and deceleration mode selection, torque vectoring and energy saving control.
First, let's talk about the control mode. The control mode is speed control, torque control, PID control or others. After taking the control mode, it is generally necessary to perform static or dynamic identification according to the control accuracy.
Second, let's look at the minimum operating frequency and the maximum operating frequency. The minimum operating frequency is the minimum speed of the motor, its heat dissipation performance is poor, and when the motor runs at a low speed for a long time, it will cause the motor to burn out. At the same time, the current in the cable increases at low speeds, which also leads to cable heating. The maximum operating frequency is generally not more than 60Hz, high frequency will make the motor high-speed operation, which is for ordinary motors, its bearings can not be a long time over the rated speed operation.
Next is the carrier frequency. The higher the carrier frequency is set, the larger the high harmonic component is, which is closely related to the length of the cable, the motor heating cable heating inverter heating and other factors.
Then the motor parameters. Inverter in the parameters set motor power, current, voltage, speed, maximum frequency, these parameters can be obtained directly from the motor nameplate.
Frequency hopping is at a certain frequency point, there may be resonance phenomenon, especially when the whole device is relatively high; in the control of the compressor, to avoid the compressor's wheezing point; the whole system requires that there must be sufficient response bandwidth, taking into account the torque characteristics of the different loads, some with acceleration response bandwidth, and some with speed response bandwidth.
Acceleration and deceleration time refers to the acceleration time and deceleration time. Acceleration time is the time required for the output frequency to rise from 0 to the maximum frequency; deceleration time is the time required to fall from the maximum frequency to 0. The acceleration and deceleration times are usually determined by the rise and fall of the frequency setting signal. The rate of rise of the frequency setting must be limited to prevent overcurrent when the motor is accelerating, and the rate of fall must be limited to prevent overvoltage when decelerating.
Torque boost, also called torque compensation, is a method of increasing the low frequency range f/V to compensate for the reduction in torque at low speeds caused by the resistance of the motor stator windings. When set to automatic, the voltage during acceleration can be automatically boosted to compensate for the starting torque so that motor acceleration proceeds smoothly. If manual compensation is used, a better curve can be selected by test according to the load characteristics, especially the starting characteristics of the load. For variable torque loads, if not properly selected, the output voltage will be too high when the load is low, which will waste the electric energy, and also the motor will have a high current when starting with the load, and the rotating speed will not be able to go up.
Electronic thermal overload protection This function is set to protect the motor from overheating, it is the CPU in the inverter calculates the temperature rise of the motor according to the value of the running current and the frequency, so as to carry out overheating protection. This function is only applicable to the occasion of "one tow one"; in the case of "one tow many", a thermal relay should be installed on each motor. Electronic thermal protection set value (%) = [motor rated current (A) / inverter rated output current (A)] x 100%.
Next is frequency limitation. That is, the upper and lower limit amplitude of the inverter output frequency. Frequency limit is to prevent misoperation or external frequency setting signal source failure, and cause the output frequency is too high or too low, in order to prevent damage to the equipment of a protection function. It can be set according to the actual situation in the application. This function can also be used as a speed limit, such as belt conveyor, due to the transport of materials is not too much, in order to reduce the wear and tear of machinery and belts, can be driven by a frequency converter and will be the upper limit of the frequency converter frequency is set to a certain value, so that the belt conveyor can be run in a fixed, lower working speed.
Then there is the bias frequency. Some are also called deviation frequency or frequency deviation setting. Its use is when the frequency is set by an external analog signal (voltage or current), this function can be used to adjust the height of the output frequency when the frequency setting signal is the lowest. Some inverters when the frequency setting signal is 0%, the deviation value can act in the range of 0 ~ fmax, some inverters (such as Ming Densha, Samsung) can also be set on the bias polarity. Such as in the debugging when the frequency setting signal is 0%, the inverter output frequency is not 0Hz, but xHz, then the bias frequency is set to negative xHz can make the inverter output frequency is 0Hz.
Next is the frequency setting signal gain. This function is only effective when the frequency is set with external analog signal. It is used to make up for the inconsistency between the voltage of the external setting signal and the voltage inside the frequency converter (+10V); at the same time, it is convenient to select the voltage of the analog setting signal, when setting, when the analog input signal is the maximum (such as 0V, 5V or 20mA), find out the frequency percentage of the output f/graphics and set it as a parameter: such as the external setting signal is 0-5V if the frequency converter output frequency 0-50Hz, then the gain signal is set to 200%. If the external setting signal is 0-5V, if the output frequency of the inverter is 0-50Hz, then set the gain signal to 200%.
Then it is torque limitation. It can be drive torque limitation and brake torque limitation. It is based on the inverter output voltage and current value (or residual voltage), by the CPU torque calculation (or PWM equivalent conversion), which can be accelerated and decelerated and constant speed operation of the impact load recovery characteristics have significant improvement. The torque limiting function realizes automatic acceleration and deceleration control. Assuming that the acceleration and deceleration time is less than the load inertia time, it also ensures that the motor automatically accelerates and decelerates according to the set torque value.