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I.Frequency converter
Frequency converter is the application of frequency conversion technology and microelectronics technology, by changing the frequency of the motor operating power supply to control the AC motor power control equipment.
Frequency converter mainly consists of rectifier (AC to DC), filter, inverter (DC to AC), braking unit, drive unit, detection unit microprocessor unit and so on.
Frequency converter rely on the internal IGBT on and off to adjust the output power supply voltage and frequency, according to the actual needs of the motor to provide the required power supply voltage, and thus achieve the purpose of energy saving, speed regulation, in addition, the frequency converter also has a lot of protection functions, such as over-current, over-voltage, overload protection and so on.
With the continuous improvement of industrial automation, frequency converter has been widely used.
Application Scenarios
1.variable frequency energy saving
Frequency converter energy saving is mainly manifested in the application of fans and pumps. Fans, pumps using frequency conversion speed control to make its speed reduction, energy saving effect is very obvious.
2.Application in automated systems
The frequency converter has a built-in 32-bit or 16-bit microprocessor with a variety of arithmetic logic operations and intelligent control functions, the output frequency accuracy of 0.1% to 0.01%, and set up a perfect detection and protection links, so it is widely used in automation systems.
3.Applications in improving process and product quality
Frequency converter can also be widely used in transmission, lifting, extrusion and machine tools and other machinery and equipment control field, it can improve the level of process and product quality, reduce the impact of the equipment and noise, extend the service life of the equipment.
4.Realization of soft start of motors
The hard start of motor will not only cause serious impact on the power grid, but also will require too high capacity of the power grid, and the large current and vibration generated during start-up will cause great damage to the baffle and valve, which is extremely unfavorable to the service life of the equipment and pipeline.
And after using frequency converter, the soft start function of frequency converter will make the starting current change from zero, and the maximum value will not exceed the rated current, which reduces the impact on the power grid and the requirement of power supply capacity, prolongs the service life of the equipment and valves, and also saves the maintenance cost of the equipment.
II.Variable Frequency Power Supply
Frequency conversion power supply is the alternating current in the utility AC → DC → AC conversion, the output is a pure sine wave, the output frequency and voltage can be adjusted within a certain range.
It is different from the frequency control controller used for motor speed regulation, and also different from the ordinary AC voltage regulator. Ideal AC power supply is characterized by stable frequency, stable voltage, internal resistance equal to zero, the voltage waveform is pure sinusoidal (no distortion).
Frequency conversion power supply is very close to the ideal AC power supply, therefore, more and more advanced developed countries will be used as a standard power supply frequency conversion power supply, in order to provide the best power supply environment for electrical appliances, to facilitate the objective assessment of electrical appliances technical performance.
There are two main types of inverter power supply: linear amplifier and SPWM switching type.
Application Scenarios
1.Precision electronics power supply
Due to the non-uniformity of power grid specifications in different countries around the world, export appliance manufacturers need power supplies that simulate power grid conditions in different countries to provide engineers with pure and reliable sinusoidal power output with low harmonic distortion, high stable frequency and regulated voltage for applications such as design and development, production line testing, and product testing for quality assurance, life time, and over-voltage/under-voltage simulation testing.
It is mainly used for manufacturing or exporting traders to test and debug the electricity for exporting electrical products and the power supply for precision instruments.
2.Industrial automation industry
After the 1970s, the development of large-scale integrated circuits and computer control technology, as well as the application of modern control theory, so that the AC power traction system gradually has a wide speed range, high speed range, high speed accuracy, fast dynamic response and reversible operation in the four quadrants and other good technical performance, in terms of speed performance can be comparable with DC power traction.
In the AC speed control technology, frequency conversion speed control has an absolute advantage, and its speed control performance and reliability continue to improve, prices continue to decrease, especially frequency conversion speed control power saving effect is obvious, and easy to realize the process of automation, favored by the industrial industry.
III.Difference between inverter and inverter power supply
Dependability
Frequency converter: The production of shore power supply assembled by frequency converter is relatively simple, because its main part “frequency converter” is purchased, so it is difficult to ensure that the frequency converter matches the parameters of other components.
Frequency conversion power supply: the power supply overall integrated design, after years of technical accumulation, to ensure stable and reliable operation of the power supply.
Safety
Frequency converter: The design of frequency converter is specialized for motor frequency conversion start-up, voltage and frequency rise synchronously during start-up, and the power supply modified with it may affect the power-using equipments, especially frequency converter, controllable rectifier, communication equipments and so on.
Frequency conversion power supply:constant frequency during startup. Shore power supply can provide pure and reliable, low harmonic distortion, high stable voltage and frequency sine wave power output, very close to the ideal AC power supply.
Three-phase unbalance
Frequency converter: The frequency converter adopts △ inverter, although the output is transformed into Y-type output through transformer, it has poor adaptability to three-phase unbalanced loads, which may increase the reverse torque in the motor, increase the temperature of the motor, decrease the efficiency, increase the energy consumption, vibration, and output loss.
Frequency conversion power supply: the inverter part adopts star mode, each phase can be loaded independently, adapting to three-phase completely unbalanced load. The unbalance degree can be up to 3% or less.
