The first generation of LS inverter selects the voltage frequency ratio scalar control method, which carries out frequency conversion speed regulation according to the linear ratio determined by the equivalent circuit of the asynchronous motor. Voltage refers to the effective value of the fundamental wave, and changing U/f can only regulate the steady-state magnetic flux and torque of the motor, not to mention dynamic control. In order to increase the torque generated by the motor at low frequency, the method of increasing the voltage and changing the compensation stator winding voltage drop with the load is usually selected, which can broaden the scale of frequency conversion speed regulation to about 20:1.
The primary feature of the second-generation LS inverter is the vector control method, which refers to the control method of the DC motor, and decomposes the stator current space vector of the asynchronous motor into rotor excitation weight and torque weight. The first is to manipulate the excitation, so the vector manipulation is called magnetic field-oriented manipulation. As for the control of torque, it is indirect. The first disadvantage of vector manipulation is the need for messy coordinate transformation operations and the need to detect rotational speed signals.
Therefore, the scheme of vector control without speed sensor is further proposed, which calculates the observed value of rotation speed according to the phase voltage and phase current of the practical operation of the asynchronous motor and the parameters of the stator and rotor winding, so as to calculate the observed value of the rotor flux flux and torque current, so as to complete the vector control of magnetic field orientation. Because the accuracy of the observed rotational speed is affected by the error between the calculated parameters used and the actual operating parameters of the motor, the speed control accuracy and speed regulation scale of vector control without speed sensor are lower than those of vector control plan with speed encoder. Generally, the speed regulation accuracy of the former is 1%, and the low frequency when the additional torque is output can only reach about 1Hz, while the speed regulation accuracy of the latter is 0.01%, and the low frequency is 0.1 Hz. However, due to the ease of use without the need for a speed encoder, the LS inverter is still popular with users for vector-operated operation without a speed sensor.
In parallel with vector control, there is also a direct torque control method, which takes the torque of the asynchronous motor as the controlled quantity, focuses on the direct control effect of torque, and does not deliberately pursue the output current as a sine waveform. The direct torque control of the asynchronous motor is to directly calculate the amplitude of the flux and the size of the torque on the stator coordinates, and directly track and condition it to obtain rapid dynamic response, and the echo speed can be as small as 1 to 2 ms. From the perspective of torque control requirements, the flux has a bit of error, which will not have a serious impact on the torque control function. The advantage of this method of operation is that it is not sensitive to changes in motor parameters.
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Interference phenomenon of LS power inverter
1. As soon as the inverter of the heat exchange station is opened, the pressure transmitter jumps randomly;
2. In the water supply controlled by the inverter, the pressure transformer is used as a signal to collect the pressure, and the pressure transformer is disturbed by the inverter;
3. When the inverter starts the motor, the voltage converter signal is unstable and beats violently;
4. Pressure transformer (4-20 ...
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The cause of the broken shaft of the motor - LS generates electricity
1. Improper device:
The motor is not concentrious with the equipment being dragged, resulting in excessive radial load on the motor, which eventually leads to metal exhaustion. When the radial load on the extension end of the motor shaft is too large, it will cause the motor shaft to have zigzag deformation in the radial direction. When the motor rotates, the shaft's ...
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LS power generation installs the switching power supply step
1. Confirm the location of the device
Before the equipment switches on and off the power supply, it is necessary to confirm the location of the equipment, and generally require the equipment to be in a ventilated, boring, non-corrosive gas and dust-free place.
2. Equipment holder
The fixed base of the switching power supply is fixed on the orientation of the equipment, and the general ...
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LS power production PLC installation and wiring skills
The PLC should be kept away from strong disturbance sources such as electric welding machines, high-power silicon rectifiers and large-scale power equipment, and should not be installed in the same switch cabinet as high-voltage electrical appliances.
Power line, control line and PLC power line and I/O line should be separated from the wiring, barrier transformer and PLC and I/O should be selected ...
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Motor & Electrical Control Technology Tips - LS Electricity Production
1. Low-voltage electrical appliances: refers to electrical appliances that play the role of on-off, maintenance, control or regulation in circuits with a rated voltage of 1200V and a rated voltage of 1500V and below.
2. Main electrical appliances: electrical appliances used to send control instructions in the automatic control system.
3. Fuse: ...
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Practical common sense in the inverter industry - LS inverter
1. The low-voltage fuse cannot be used as an overload maintenance of the motor.
2. The additional voltage of the fuse must be greater than or equal to the operating voltage of the distribution line.
3. The additional current of the fuse must be greater than or equal to the ...
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Analysis of the fault problem of LS power terminal block
From the point of view of application, the function of the terminal block should be achieved: it is necessary to conduct the local conduction of the touch part, and the touch is reliable. The insulating part should not be conducted, and it is necessary to insulate it firmly. There are three common forms of fatal problems in terminal blocks:
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Specifications for the use of power converters
Operating regulations for power inverters
Maintenance & Installation
Work according to the weight of the product.
The number of inverter boxes cannot be stacked in excess of the specified number.
Install according to the user manual.
Do not open the case during transport.
Do not place ...
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Selection of AC contactors in the field of building electrical - LS power production
1. The series and parallel connection application of contactors Many electrical equipment are single-phase loads, so several poles of multi-pole contactors can be used in parallel. Such as resistance furnaces, welding transformers, etc. When using several poles in parallel, a smaller capacity contactor can be used. However, it must be noted that after parallel ...
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The cause of the failure of low-voltage electrical appliances - LS power generation
In the control circuit of low-voltage electrical appliances, there are simple low-voltage components such as: buttons, safe, etc.; There are also slightly messy low-voltage electrical control components, such as circuit breakers, touch devices, time relays, thermal relays and other simple components, which makes it necessary to diagnose and analyze the cause of the problem.
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The lightning protection port of the inverter - LS generates electricity
According to the applied engineering practice, variable frequency drive (VFD) lightning strikes can be roughly divided into direct lightning, induced lightning and conducted lightning. But no matter what form it takes to reach the device, it can be summarized as a lightning surge from the following four parts, which are called lightning protection ports here, with V ...
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The difference between inverter and power saver - LS produces electricity
First, the frequency conversion skill is only one of the many power-saving skills, including voltage regulation and current limiting, power factor compensation, phased power regulation, frequency conversion, chopping, filtering, energy feedback and other skills, even if the power saver using the principle of frequency conversion is concerned, the frequency converter is only power-saving.
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Introduction to the control method of LS power inverter
Inverter control method: low-voltage general frequency conversion output voltage is 380-650V, output power is 0.75-400kW, operating frequency is 0-400Hz, and its main circuit adopts AC-DC-AC circuit. Its control methods have gone through the following five generations.
1U/f=C sine pulse width modulation ...
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The difference between multi-function inverter and general-purpose inverter - LS produces electricity
With the deepening of factory automation, the high efficiency and low cost of active warehouses, elevators, transfer systems, etc., as well as the high speed, high efficiency and high precision of small CNC machine tools, kneading and forming machines, textile and film machinery, etc.
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How LS PLC works
Although many names such as relays, timers and counters are often used in the ladder diagram programs used by LS PLC, LS PLC does not have these hardware physically, but uses memory and program programming to do logic control and editing, and connects to external machines through output components.
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LS power production contactors are used in this area
LS contactors are divided into AC contactors (voltage AC) and DC contactors (voltage DC), which are used in electricity, power distribution and consumption. Contactor in a broad sense refers to the electrical appliances that use the current flowing through the coil to generate a magnetic field and close the contact to control the load in industrial electricity.
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Methods for extending the service life of inverters - LS generates electricity
1. The influence of electromagnetic disturbance on the inverter:
In the modern industrial control system, the microcomputer or PLC control technology is mostly selected, and in the process of system planning or transformation, it is necessary to pay attention to the disturbance of the inverter to the microcomputer control board. The inverter is disturbed by the outside world, because the user ...
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The principle and function of the power production contactor
The working principle of the power production contact is: when the contact coil is energized, the coil current generates a magnetic field, and the generated magnetic field leads the static iron core to produce electromagnetic attraction to the iron core, and drives the AC contact action, the normally closed contact is disconnected, the normally open contact is closed, and the two are connected to each other. When the coil is de-energized, the electric ...
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The basic component of the inverter is LS power generation
The inverter is usually divided into 4 parts: the rectifier unit, the high-capacity capacitor, the inverter and the controller.
Rectifier unit: converts alternating current with a fixed operating frequency into direct current.
High Capacitance: Stores converted electrical energy.
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Parameter setting of LS power inverter
The inverter is a high-tech intelligent product, in order to let it complete the specified control mission, it must be set parameters, otherwise, it is like the computer is not installed and used, and it cannot be operated normally. The parameter setting is carried out by the control surface of the inverter. All kinds of inverters ...
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