One acceleration and deceleration time
The acceleration time is the time required for the output frequency to increase from zero to the maximum frequency, and the deceleration time is the time required to fall from the maximum frequency to zero. Normally, the acceleration/deceleration time is determined by the rise and fall of the frequency setting signal. When the motor accelerates, the rate of rise of the frequency setting must be limited to prevent over-current, and when decelerating, the rate of decrease should be limited to prevent over-voltage.
Acceleration time setting requirements: Limit the accelerating current below the overcurrent capacity of the inverter, and cause the inverter to trip without over-current stalling. The deceleration time setting points are: to prevent the smoothing circuit voltage from being too large, and not to make the regeneration overvoltage stall. Make the frequency converter trip. Acceleration/deceleration time can be calculated according to the load, but in the debugging often take the load and experience to set a longer acceleration and deceleration time, through the start, stop the motor to observe whether there is over current, over voltage alarm; then gradually set the acceleration and deceleration time To shorten, to the principle of no alarm in operation, repeated operation a few times, you can determine the best acceleration and deceleration time.
Two torque boost
Also called torque compensation is a method of increasing the low frequency range f/V in order to compensate for torque reduction at low speed caused by the stator winding resistance of the motor. When set to automatic, the voltage at the time of acceleration can be automatically increased to compensate for the starting torque and smooth the motor acceleration. If manual compensation is used, a better curve can be selected by the test according to the load characteristics, especially the starting characteristics of the load. For the variable torque load, if the improper selection is made, the output voltage at the low speed will be too high and the power will be wasted. Even if the motor starts with the load, the current will be large and the speed will not increase.
Three electronic thermal overload protection
This function is set to protect the motor from overheating. It is the CPU in the inverter that calculates the temperature rise of the motor based on the running current value and frequency, so as to perform overheat protection. This function is only applicable to "one-on-one" occasions. When "one to many" is required, thermal relays should be installed on each motor.
Electronic thermal protection set value (%) = [motor rated current (A) / inverter rated output current (A)> × 100%.
Four frequency restrictions
That is, the inverter output frequency upper and lower limit amplitude. The frequency limit is a protection function that prevents the output frequency from becoming too high or too low to prevent misoperation or external frequency setting signal source failure. In the application can be set according to the actual situation. This function can also be used as a speed limit, such as some belt conveyors, due to the transport of material is not too much, in order to reduce the wear of the machinery and the belt, can drive by the inverter, and set the inverter upper frequency to a certain frequency value This allows the belt conveyor to operate at a fixed, lower operating speed.
Five offset 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 output frequency of the frequency setting signal at the lowest level, as shown in Figure 1. When some frequency converters set the frequency setting signal to 0%, the deviation value can be used within the range of 0 to fmax. Some inverters (such as Mingdian and Sanhe) can also set the offset polarity. If the frequency setting signal is 0% in the debugging, the output frequency of the inverter is not 0Hz, but is xHz, then setting the offset frequency to negative xHz can make the inverter output frequency to 0Hz.
Six frequency setting signal gain
This function is only valid when the frequency is set with an external analog signal. It is used to compensate for the inconsistency between the externally set signal voltage and the voltage inside the inverter (+10v); at the same time, it is convenient for the analog setting signal voltage to be selected. When the analog input signal is set to the maximum (such as 10v, 5v or 20mA), find the percentage of frequency that can output f/V graph and set it as a parameter; if the external setup signal is 0~5v, if the inverter output frequency is 0~50Hz, then the gain signal will be Set it to 200%.
Seven torque limit
Can be divided into two kinds of drive torque limit and brake torque limit. It is based on the inverter output voltage and current value, the torque calculation by the CPU, which can significantly improve the impact load recovery characteristics of acceleration and deceleration and constant speed operation. The torque limit function enables automatic acceleration and deceleration control. Assuming that the acceleration/deceleration time is less than the load inertia time, the motor can also be guaranteed to automatically accelerate and decelerate according to the torque setpoint.
The drive torque function provides powerful starting torque. In the 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 is set too short, the motor torque will not exceed the maximum set value. Larger drive torque is favorable for starting, and it is better to set 80 to 100%.
The smaller the setting value of the braking torque, the greater the braking force is, and it is suitable for the occasion of rapid acceleration and deceleration. For example, if the setting value of braking torque is set too large, an over-voltage alarm phenomenon will occur. If the braking torque is set to 0%, the total amount of regenerative energy added to the main capacitor can be made close to zero, so that the motor can decelerate to a stop without tripping without using a braking resistor during deceleration. However, on some loads, if the braking torque is set to 0%, there will be a brief idling during deceleration, which will cause the inverter to start repeatedly and the current will fluctuate greatly. In severe cases, the inverter will trip, and attention should be paid.
Eight acceleration and deceleration mode selection
Also called acceleration and deceleration curve selection. Generally frequency converter has linear, non-linear and S three kinds of curves, usually choose linear curve mostly; Non-linear curve is suitable for changing torque load, such as fan,etc.; S curve is suitable for constant torque load, its acceleration and deceleration change is more slowly. According to the characteristics of the load torque, set the corresponding curve, but there are exceptions, the author when debugging a boiler induced draft fan inverter, the first to choose the non-linear curve acceleration and deceleration curve, together with the inverter to run the trip, adjust Changing many parameters has no effect, and it becomes normal after changing to S curve. The reason for this is as follows: Before the start of the induced draft fan due to the flue gas flow and self-rotation, and reversed to become a negative load, so select the S curve, so that the frequency of just starting the rise is slow, thus avoiding the inverter The occurrence of tripping is, of course, the method used for inverters that do not have a DC braking function.
Nine Torque Vector Control
The vector control is based on the theory that the asynchronous motor and the DC motor 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, respectively, to control, and at the same time, output the combined stator current 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 maximum torque under various operating conditions, especially when the motor is in a low speed operation area.
Nowadays, almost all frequency converters use non-feedback vector control. Because the frequency converter can compensate for slip according to the magnitude and phase of the load current, the motor has very hard mechanical characteristics. It can meet the requirements for most occasions, and it is not necessary to use the inverter. Externally set speed feedback circuit. The setting of this function can be based on the actual situation in the effective and invalid one can be selected.
The related function is the slip compensation control. The function is to compensate 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.
Ten energy-saving controls
Fans and pumps are all reduced torque loads. That is, as the speed decreases, the load torque is proportional to the square of the speed, while the inverter with energy-saving control function is designed with a dedicated V/f mode. This mode can be improved. The efficiency of the motor and frequency converter, which can automatically reduce the output voltage of the inverter according to the load current, so as to achieve the purpose of energy saving, can be set as valid or invalid according to the specific circumstances.
It should be noted that these two parameters are very advanced, but some users can't enable these two parameters at the time of equipment modification. That is, after the inverter is started, it will trip frequently and everything will be normal after it is deactivated. The reasons are as follows: (1) The original motor parameters and the motor parameters required by the inverter are too different. (2) The function of setting parameters is not well understood. 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 manual setting and automatic reading of the motor parameters are not performed, or the reading method is improper.
What is Industrial DTU? Industrial DTU characteristics and application field analysis
What is DTU?
A Data Transfer unit (DTU) is a wireless terminal device that converts serial port data into IP data or IP data into serial port data over a wireless communication network.
Second, industrial DTU characteristics?
D220 is an industrial 4G DTU based on 4G wireless network, the product uses high-performance industrial embedded processor, real-time operating system as the software support platform, to ensure that the data link is smooth at any time, to provide users with high-speed, stable and reliable data transmission. It can be easily and quickly arranged in the industrial site, and can be used in harsh environments.
Hardware features:
Anti-interference design, suitable for harsh electromagnetic environment application requirements
Wide voltage power supply design, support DC5V-35V power input, built-in power reverse protection and overvoltage and overcurrent protection
The serial port can be a service serial port or a data serial port
Supports the many-to-many link configuration between the service serial port and the center
Select industrial-grade devices and optimize electromagnetic compatibility design to meet the requirements of harsh application environments
The D220 supports backward compatible 2G/3G network access based on 4G network.
Built-in hardware watchdog, regular detection mechanism, automatic resetting of abnormal equipment.
Complete industrial environment design requirements, all-metal structure, the whole machine has passed the strict electromagnetic compatibility test, CE certification
Software features:
Multi-center mode/Multi-backup mode (up to five multi-centers/backup centers)
Different serial ports can be used as maintenance or service serial ports, and different service serial ports can be connected to different multi-centers.
Multi-protocol upper development kit support (compatible with communication protocols of multiple DTU manufacturers, which can achieve seamless replacement of DTU)
Supports ICMP and LCP link detection technologies and keeps heartbeat alive, ensuring the stability and reliability of the network and communication
Supports local serial port upgrade and remote software upgrade
Supports TCP, UDP, DUTCP, DCUDP and other connection protocols
Supports multiple encryption modes to ensure secure data transmission
3. Application fields
D220 4G DTU conforms to industrial design, complete functions, stable transmission, widely used in environmental protection, water conservancy, meteorological industries; Industrial control field; Industry and special environment, oil and gas, heating industry, etc.
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Shenzhen MovingComm Technology Co., Ltd. , https://www.szmovingcomm.com