There are many functional parameters of the inverter, and there are generally dozens or even hundreds of parameters for users to choose. In practice, it is not necessary to set and debug every parameter, and most of them only need to use the factory setting value. However, some parameters are closely related to the application of practice, and some are related to each other, so they should be set and debugged according to practice. The functions of various types of inverters are different, and the names of the same functional parameters are also inconsistent, so this paper takes the basic parameters of Fujifilm inverters as an example. Since the basic parameters are simply available for all types of inverters, it is completely possible to draw inferences from one another.
1. Acceleration and deceleration time
The acceleration time is the time it takes for the output frequency to rise from 0 to the highest frequency, and the deceleration time is the time it takes to go down from the highest frequency to 0. Generally, the acceleration and deceleration time is confirmed by the rise and fall of the frequency setting signal. When the motor accelerates, the rise rate set by the frequency must be bound to prevent overcurrent, and when the motor is decelerating, the falling rate must be bound to prevent overvoltage.
Acceleration time setting requirements: the acceleration current is bound below the overcurrent capacity of the inverter, so as not to cause the inverter to trip due to the overrun; The key to setting the deceleration time is to prevent the voltage of the lubricating circuit from being too large, and not to cause the regenerative overvoltage to stall and trip the inverter. The acceleration and deceleration time can be calculated according to the load, but in the debugging, it is often used to set a longer acceleration and deceleration time according to the load and experience, and check whether there is an overcurrent and overvoltage alarm after starting and stopping the motor; Then the acceleration and deceleration time is gradually shortened, and the best acceleration and deceleration time can be confirmed by repeating the operation several times according to the criterion that no alarm is generated during the operation.
Second, the torque is increased
Also known as torque compensation, it is a method to increase the low-frequency scale f/V in order to compensate for the decrease in torque at low speed caused by the resistance of the stator winding 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 selected, the best curve can be selected according to the load characteristics, especially the starting characteristics of the load. Regarding variable torque loads, if the selection is not done properly, the output voltage at low speed will be too high, and the phenomenon of wasting electric energy will even occur, and even the phenomenon that the motor will have a large current when starting with a load, and the speed will not go up.
3. Electronic thermal overload protection
This function is set to protect the motor from overheating, which is to calculate the temperature rise of the motor according to the operating current value and frequency of the CPU in the inverter, and then carry out overheating protection. This function is only applicable to the occasion of "one to one", and in the case of "one to many", thermal relays should be installed on each motor.
Electronic thermal protection setpoint (%) = [rated current of motor (A) / rated output current of inverter (A)] × 100%.
4. Frequency Bondage
That is, the upper and lower amplitudes of the output frequency of the inverter. Frequency restraint is a protective function to prevent misoperation or external frequency setting signal source from malfunctioning, 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 practice situation in use. This function can also be used as a speed limit, such as a belt conveyor, because the material is not too much, in order to reduce the wear and tear of machinery and belt, you can choose to use the inverter drive, and the upper limit frequency of the inverter is set to a certain frequency value, so that the belt conveyor can run on a fixed, lower operating speed.
5. Bias frequency
Some are also called error frequency or frequency error setting. Its purpose is that when the frequency is set by an external imitation signal (voltage or current), this function can be used to adjust the frequency to set the output frequency when the signal is low, as shown in Figure 1. When the frequency setting signal of some inverters is 0%, the error value can be effective in the scale of 0-fmax, and some inverters (such as Mingdianshe and Sanken) can also set the bias polarity. If the output frequency of the inverter is not 0Hz but xHz when the frequency setting signal is 0% in debugging, then the bias frequency is set to negative xHz at this moment to make the output frequency of the inverter 0Hz.
6. Frequency setting signal gain
This function is only useful when setting the frequency with an external imitation signal. It is used to compensate for the inconsistency between the externally set signal voltage and the internal voltage (+10V) of the inverter; When the input signal is the largest (such as 10v, 5v or 20mA), the frequency percentage that can output the f/V graph can be calculated and set as a parameter. If the external setting signal is 0-5V, if the output frequency of the inverter is 0-50Hz, the gain signal can be set to 200%.
7. Torque restraint
It can be divided into two types: driving torque restraint and brake torque restraint. It is based on the output voltage and current value of the inverter, and the torque is calculated by the CPU, which can significantly improve the shock load recovery characteristics during acceleration, deceleration and constant speed operation. The torque restraint function enables automatic acceleration and deceleration control. Assuming that the acceleration and deceleration time is less than the load inertia time, the motor can be automatically accelerated and decelerated according to the torque setting value.
The drive torque function provides a robust starting torque, and in steady-state operation, the torque function will control the motor deterioration, and the motor torque will be bound within 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. When the acceleration time is set too short, the motor torque will not exceed the Z-maximum set value. A large drive torque is beneficial to the start, so it is more appropriate to set it to 80-100%.
The smaller the braking torque setting value, the greater the braking force, which is suitable for the occasion of rapid acceleration and deceleration, if the braking torque setting value is set too large, there will be an overvoltage alarm phenomenon. 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 the motor can be decelerated to a stop without using a braking resistor when decelerating. However, in some loads, such as when the braking torque is set to 0%, there will be a short time idle phenomenon when decelerating, which constitutes the repeated start of the inverter, and the current is not firm in a large way, and the inverter will trip in serious cases, which should cause attention.
8. Selection of acceleration and deceleration methods
It is also called acceleration and deceleration curve selection. Generally, there are three kinds of curves: linear, nonlinear and S, and most of them choose linear curves; The nonlinear curve is suitable for variable torque loads, such as fans, etc.; The S-curve is suitable for constant torque loads, and its acceleration and deceleration changes more slowly. Punctuality can be based on the load torque characteristics, the corresponding curve can be selected, but there are exceptions, the author in the debugging of a boiler inverter, the acceleration and deceleration curve is selected as a nonlinear curve, and the inverter trips when the operation is started, and the adjustment and change of many parameters has no effect, and then it is normal after changing to the S curve. The reason is: the induced draft fan rolls by itself due to the flue gas activity before starting, and becomes a negative load when it rotates, so that the S curve is selected, so that the frequency rise speed at the beginning of the start is slower, and then the inverter tripping is prevented, of course, this is the method selected for the inverter without starting DC braking function.
9. Torque vector control
Vector control is based on the theoretical belief that asynchronous motors have the same torque generation mechanism as DC motors. The vector control method is to decompose the stator current into regular magnetic field current and torque current, control them separately, and output the stator current composed of the two to the motor together. Therefore, in principle, the same control function can be obtained as that of DC motors. Using the torque vector control function, the motor can output the highest torque under various operating conditions, especially in the low-speed operation area.
Now the inverter is simply selected non-reverberation vector control, because the inverter can be compensated for the slip according to the load current and phase, so that the motor has very hard mechanical characteristics, and the requirements can be met in most occasions, and there is no need to set up the speed repercussion circuit outside the inverter. This function can be set by selecting one of useful and ineffective according to the practical situation.
A related function is slip compensation control, the effect of which is to compensate for speed errors caused by unfirm loads, and a slip frequency corresponding to the load current can be added. This function is primarily used for positioning control.
10. Energy-saving control
Fans and pumps are attributed to the reduced torque load, that is, with the decrease of speed, the square share of load torque and speed decreases, and the inverter with energy-saving control function is planned to have a special V/f mode, which can improve the efficiency of the motor and inverter, which can automatically reduce the output voltage of the inverter according to the load current, and then achieve the energy-saving intention, which can be set to useful or invalid according to the specific situation.
It should be clarified that the two parameters of nine and ten are very advanced, but there are some users who cannot enable these two parameters in the equipment transformation, that is, the inverter trips frequently after it is enabled, and everything is normal after it is deactivated. The reasons are: (1) The parameters of the original motor are too different from the motor parameters required by the inverter. (2) Insufficient understanding of the function of setting parameters, such as the energy-saving control function can only be used in the V/f control method, and cannot be used in the vector control method. (3) The vector control method is enabled, but the manual setting and automatic reading of the motor parameters are not carried out, or the reading method is improper.
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