Inverter parameter settings - Solutions - Huaqiang Electronic Network

Single chip microcomputer STM32L151CCU6

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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There are many setting parameters of the inverter, each parameter has a certain range of selection. In use, it is often encountered that the inverter cannot work normally due to improper setting of individual parameters. Therefore, the relevant parameters must be correctly set. set.
1, control method:
That is, speed control, torque control, PID control or other means. After the control method is adopted, static or dynamic identification is generally performed according to the control precision.
2, the minimum operating frequency:
That is, the minimum speed of the motor running, when the motor is running at low speed, its heat dissipation performance is very poor, and the motor runs at a low speed for a long time, which will cause the motor to burn out. At low speeds, the current in the cable also increases, which can also cause the cable to heat up.
3, the highest operating frequency:
The general frequency of the inverter is up to 60Hz, and some even reach 400 Hz. The high frequency will make the motor run at high speed. For ordinary motors, the bearings can't run for a long time at the rated speed. Can the rotor of the motor withstand such a kind? Centrifugal force.
4, carrier frequency:
The higher the carrier frequency setting, the higher the higher harmonic component, which is closely related to the length of the cable, the heating of the motor, and the heating of the cable heating inverter.
5, motor parameters:
The 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 the entire device is relatively high; when controlling the compressor, the surge point of the compressor should be avoided.
7. Acceleration/deceleration time The acceleration time is the time required for the output frequency to rise from 0 to the maximum frequency. The deceleration time is the time required to fall from the maximum frequency to 0. The acceleration and deceleration time is usually determined by the frequency setting signal rising and falling. When the motor is accelerating, the rate of increase of the frequency setting must be limited to prevent overcurrent, and when decelerating, the rate of decrease is limited to prevent overvoltage.
Acceleration time setting requirement: Limit the acceleration current below the overcurrent capacity of the inverter, and do not cause the inverter to trip due to the over-speed. The deceleration time setting point is: prevent the smoothing circuit voltage from being too large, and do not make the regenerative overvoltage stall. Let the frequency converter trip. Acceleration and deceleration time can be calculated according to the load, but in the debugging, it is often set to set the long acceleration/deceleration time according to the load and experience. Observe the overcurrent and overvoltage alarm by starting and stopping the motor; then gradually set the acceleration/deceleration time. Shorten, the principle of no alarm occurs during operation, and repeat the operation several times to determine the optimal acceleration and deceleration time.
8. Torque boosting, also called torque compensation, is a method to increase the low frequency range f/V to compensate for the torque reduction at low speeds 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 accelerates smoothly. If manual compensation is used, a better curve can be selected by experiment depending on the load characteristics, especially the starting characteristics of the load. For variable torque loads, if the selection is improper, the output voltage will be too high at low speed, and the phenomenon of wasting electric energy may even occur when the motor is loaded with load and the current is large, and the speed is not going up.
9. Electronic thermal overload protection This function is set to protect the motor from overheating. It is the CPU inside the inverter calculates the temperature rise of the motor according to the running current value and frequency, thus performing overheat protection. This function is only applicable to the “one-for-one” occasion, and in the “one-to-many” case, a thermal relay should be added to each motor.
The electronic thermal protection set value (%) = [motor rated current (A) / inverter rated output current (A)] × 100%.
10. The frequency limit is the upper and lower limit amplitude of the inverter output frequency. The frequency limit is a protection function that prevents the device from malfunctioning or the external frequency setting signal source is faulty, causing the output frequency to be too high or too low to prevent damage to the device. In the application, it can be set according to the actual situation. This function can also be used for speed limit. If there are some belt conveyors, because there is not much material to be transported, in order to reduce the wear of machinery and belts, the inverter can be driven and the upper limit frequency of the inverter can be set to a certain frequency value. This allows the belt conveyor to operate at a fixed, low working speed.
11. Some of the offset frequencies are also called deviation frequency or frequency deviation setting. Its purpose is to adjust the output frequency of the lowest frequency setting signal when the frequency is set by an external analog signal (voltage or current). In some inverters, when the frequency setting signal is 0%, the deviation value can be applied in the range of 0 to fmax. Some inverters (such as Mingdian, Sanhao) can also set the offset polarity. For example, when the frequency setting signal is 0% during debugging, the output frequency of the inverter is not 0Hz, but it is xHz. At this time, set the offset frequency to negative xHz to make the inverter output frequency 0Hz.
12. Frequency setting signal gain This function is valid only when the frequency is set with an external analog signal. It is used to compensate for the inconsistency between the external set signal voltage and the internal voltage of the inverter (+10v); at the same time, it is convenient to select the analog set signal voltage. When setting, when the analog input signal is maximum (such as 10v, 5v or 20mA), find the percentage of the frequency that can output the f/V pattern and set it as the parameter; if the external setting signal is 0~5v, if the output frequency of the inverter is 0~50Hz, the gain signal will be Set to 200%.
13. The torque limit can be either the drive torque limit or the brake torque limit. It is based on the output voltage and current value of the inverter, and is calculated by the CPU. It can significantly improve the shock load recovery characteristics during acceleration and deceleration and constant speed operation. The torque limit function enables automatic acceleration and deceleration control. It is assumed that the acceleration/deceleration time is less than the load inertia time, and the motor can be automatically accelerated and decelerated according to the torque set value.
The drive torque function provides a 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. When the acceleration time setting is too short, the motor torque will not exceed the maximum set value. A large driving torque is advantageous for starting, and it is preferable to set it to 80 to 100%.
The smaller the brake torque setting value is, the larger the braking force is. It is suitable for the occasion of sudden acceleration and deceleration. If the brake torque setting value is set too high, an overvoltage alarm phenomenon will occur. 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 when the motor is decelerating, it can be decelerated to stop without tripping without using the braking resistor. However, in some loads, if the braking torque is set to 0%, a short idling phenomenon will occur during deceleration, causing the inverter to start repeatedly, the current fluctuates greatly, and the inverter will trip if it is serious, which should be noted.
14. Acceleration/deceleration mode selection is also called acceleration/deceleration curve selection. Generally, the inverter has three kinds of curves: linear, nonlinear and S. Usually, most of the linear curves are selected; the nonlinear curve is suitable for variable torque loads, such as fans; the S curve is suitable for constant torque loads, and the acceleration and deceleration changes are slow. According to the load torque characteristics, the corresponding curve can be selected according to the load torque characteristics. However, when debugging the inverter of a boiler induced draft fan, the nonlinear curve is selected for the acceleration/deceleration curve, and the inverter is tripped and adjusted together. Changing many parameters has no effect, and then it is normal after changing to the S curve. The reason is: before starting, the induced draft fan rotates by itself due to the flue gas flow, and reverses to become a negative load, so the S curve is selected, so that the frequency of the initial start is slower, thus avoiding the inverter. The occurrence of a trip, of course, is the method used for a frequency converter that does not have a DC braking function. #p#分页头#e#
15. Torque vector control vector control is based on the theory that asynchronous motor and DC motor have the same torque generation mechanism. The vector control method is to decompose the stator current into predetermined magnetic field currents and torque currents, and separately control the stator currents to be output to the motor. Therefore, the same control performance as the DC motor can be obtained in principle. With the torque vector control function, the motor can output the maximum torque under various operating conditions, especially the motor running in the low speed range.
Nowadays, almost all inverters adopt non-feedback vector control. Because the inverter can compensate for the slip according to the magnitude and phase of the load current, the motor has very hard mechanical characteristics. For most occasions, the requirements can be met without the need for the inverter. The speed feedback circuit is externally set. The setting of this function can be selected among the valid and invalid according to the actual situation.
The function related to this is the slip compensation control, which is used to compensate for the speed deviation 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 are all torque-reducing loads, that is, as the speed decreases, the load torque decreases proportionally to the square of the speed, and the inverter with energy-saving control function is designed with a dedicated V/f mode. The mode can improve the efficiency of the motor and the frequency converter, and can automatically reduce the output voltage of the inverter according to the load current, thereby achieving the purpose of energy saving, and can be set to be effective or invalid according to specific conditions.
It should be noted that the two parameters of Nine and Ten are very advanced, but some users can not enable these two parameters in the equipment transformation, that is, the inverter trips frequently after being activated, and everything is normal after the deactivation. The reasons are:
(1) The difference between the original motor parameters and the motor parameters required by the inverter is too large.
(2) The function of setting parameters is not enough. For example, the energy-saving control function can only be used in the V/f control mode and cannot be used in the vector control mode.
(3) The vector control mode is enabled, but the manual setting and automatic reading of the motor parameters are not performed, or the reading method is improper.