Inverter parameter setting method - Senlan

1. Control method:

i.e. speed control, rotation control, PID control, or other methods. After the control method is adopted, it is generally necessary to carry out static or dynamic identification according to the control accuracy.

2. Minimum operating frequency:

That is, the minimum speed of motor operation, when the motor is operating at low speed, its heat dissipation performance is very poor, and the motor will be incinerated when the motor is operated at low speed for a long time. And at low speeds, the current in the cable will also increase, which will also cause the cable to heat up.

Inverter parameter setting method - Senlan

Inverter parameter setting method - Senlan

3. Highest operating frequency:

The maximum frequency of the general inverter is 60Hz, and some even to 400 Hz, and the high frequency will make the motor work at high speed, which is for the general motor, its bearing can not be operated at extra speed for a long time, and whether the rotor of the motor can withstand such centrifugal force.

4. Carrier frequency:

The higher the carrier frequency setting, the larger the higher harmonic component, which is closely related to the length of the cable, the heating of the motor, the heating of the cable and the heating of the inverter.

5. Motor parameters:

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

6. Frequency hopping:

At a certain frequency point, resonance may occur, especially when the whole device is relatively high; When operating the compressor, avoid the surge point of the compressor.

7. Acceleration and deceleration moments

The acceleration time is the time it takes for the output frequency to rise from 0 to the maximum frequency, and the deceleration time is the time it takes to drop from the maximum frequency to 0. Usually, the acceleration and deceleration time is determined by the rise and fall of the frequency setting signal. When the motor accelerates, the rise rate of the frequency setting must be constrained to avoid overcurrent, and when the motor is decelerating, the fall rate must be constrained to avoid overvoltage.

Speed up the time setting requirements: the acceleration current is constrained below the overcurrent capacity of the inverter, so that the overflow will not cause the inverter to trip; The key to setting the deceleration time is to avoid excessive voltage of the smoothing circuit, 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 taken to set a longer acceleration and deceleration time according to the load and experience, and observe 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 optimal acceleration and deceleration time can be determined by repeating the operation several times in the principle that no alarm occurs during the operation.

8. Torque increase

Also known as torque compensation, it is a method to increase the low frequency range 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 active, the voltage at the time of acceleration can be actively increased to compensate for the starting torque, so that the motor can be accelerated smoothly. If manual compensation is selected, the best curve can be selected according to the load characteristics, especially the starting characteristics of the load. For variable torque loads, if the selection is not appropriate, the output voltage at low speed will be too high, and the phenomenon of wasting electric energy, and even the phenomenon that the motor will start with a load and the current will be large, and the speed will not go up.

9. Electronic thermal overload maintenance

This function is set to maintain the overheating of the motor, which is that the CPU in the inverter calculates the temperature rise of the motor according to the operating current value and frequency, so as to carry out overheating maintenance. 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 Maintenance Setpoint (%) = [Motor Extra Current (A) / Inverter Extra Output Current (A)]× 100%.

10. Frequency Constraints

That is, the upper and lower amplitudes of the output frequency of the inverter. Frequency constraint is a maintenance function to avoid misoperation or external frequency setting signal source problems, and the output frequency is too high or too low, so as to prevent damage to the equipment. You can set it according to the actual situation in the app. 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 belts, you can choose to use the inverter to drive, and the upper limit frequency of the inverter is 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. It is used to adjust the output frequency when the frequency is set by an external analog signal (voltage or current), and the output frequency is at the lowest when the frequency is set. When the frequency setting signal is 0%, the error value can be in the range 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 the debugging, then the bias frequency can be set to negative xHz to make the output frequency of the inverter 0Hz.

12. Frequency setting signal gain

This function is only useful when setting the frequency with an external analog 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 analog input signal is the maximum (such as 10v, 5v or 20mA), find the frequency percentage that can output the f/V graph and set it 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%.

13. Torque constraint

There are two types of driving torque constraint and brake torque restraint. It is based on the output voltage and current values of the inverter, and the torque is calculated by the CPU, which can significantly improve the shock load recovery characteristics during acceleration and deceleration and constant speed operation. The torque restraint function enables active acceleration and deceleration control. Assuming that the acceleration and deceleration time is less than the load inertia time, the motor can also be guaranteed to actively accelerate and decelerate according to the torque set value.

The driving torque function provides a strong starting torque, and in the steady-state operation, the torque function will control the motor to deviate, and the motor torque is constrained within the maximum set value, when the load torque suddenly increases, and even when the acceleration time is set too short, it will not cause the inverter to trip. If the acceleration time is set too short, the motor torque will not exceed the maximum set value. A large drive torque is good for starting, so it is better 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, such as the overvoltage alarm phenomenon when the braking torque setting value is set too much. If the braking torque is set to 0%, the total amount of regeneration applied to the main capacitor can be close to 0, so that the motor can be decelerated to a stop without using a braking resistor when decelerating. However, on some loads, such as when the braking torque is set to 0%, the phenomenon of short time and idle will appear when decelerating, resulting in repeated start of the inverter, and the current will fluctuate greatly, and the inverter will trip when it is severe, which should be noted.

14. Selection of acceleration and deceleration forms

It is also called acceleration and deceleration curve selection. Generally, there are three kinds of curves for inverters: linear, nonlinear and S, and most of them usually select linear curves; The nonlinear curve is suitable for variable torque loads, such as fans, etc.; The S-curve is suitable for constant torque loads, where the acceleration and deceleration changes more slowly. Punctuality can be based on the load torque characteristics, select the corresponding curve, but there are exceptions, the author in the debugging of a boiler inverter fan inverter, the acceleration and deceleration curve selection of nonlinear curve, together with the operation of the inverter tripped, adjustment and change of many parameters have no effect, and then changed to the S curve after the normal. The reason is: the induced draft fan rotates by itself because of the flue gas flow before starting, and reverses and becomes a negative load, so that the S curve is selected, so that the frequency rise speed at the beginning of the start is slower, so as to avoid the occurrence of the inverter tripping, of course, this is the method selected for the inverter without starting DC braking function.

15. Torque vector manipulation

Vector control is based on the theoretical belief that asynchronous motors and DC motors have the same torque generation mechanism. The vector control method is to decompose the stator current into the specified magnetic field current and torque current, control them separately, and output the stator current after the synthesis of the two to the motor. Therefore, in principle, the same handling performance can be obtained as that of a DC motor. With the torque vector control function, the motor can output the maximum torque under various working conditions, especially in the low-speed working area.

At present, almost all inverters are controlled by non-response vectors, because the inverter can compensate for the slip according to the load current and phase, so that the motor has very hard mechanical characteristics, and can meet the requirements for most occasions, without setting the speed response circuit outside the inverter. The setting of this function can be based on the actual situation, and it is enough to choose one of the useful and ineffective.

The related function is the slip compensation control, which is used to compensate for the speed error caused by the load fluctuation, and the slip frequency corresponding to the load current can be added. This function is mainly used for positioning control.

16. Energy-saving control

Fans and pumps all belong to the reduced torque load, that is, with the decrease of speed, the square of the load torque and the speed decreases, and the inverter with energy-saving control function is designed with a special V/f form, which can improve the power of the motor and inverter, which can actively reduce the output voltage of the inverter according to the load current, so as to achieve the purpose of energy saving, and can be set to useful or ineffective 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 for this 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 energy-saving control function can only be used in the V/f control method, not in the vector control method.

(3) The vector control method is enabled, but the manual setting and active reading of the motor parameters are not carried out, or the reading method is inappropriate.

Inverter parameter setting method - Senlan

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