Frequency conversion cable used capable of restraining higher harmonic
A frequency conversion cable and high-order harmonic technology, applied to power cables with shielding layers/conductive layers, etc., can solve problems such as cable structure and laying length limitations, impedance mismatch, cable insulation and motor insulation damage, etc. Flow rate and safe operation guarantee, avoiding the danger of resonance, and avoiding the effects of accidents
Inactive Publication Date: 2012-07-11
SHANGHAI MORN ELECTRIC EQUIPMENT CO LTD
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Problems solved by technology
[0008] ①. Strong electromagnetic interference to nearby communication, signal, monitoring, control, computer, relay protection and other weak current systems, resulting in distortion, malfunction or malfunction of the above systems, resulting in accidents
[0009] ② High-order harmonics will generate bearing currents in the entire transmission system, resulting in accelerated wear of bearings and transmission components, thereby reducing the service life of the system
[0010] ③. Due to the impedance mismatch between the frequency converter, the cable and the motor, the frequency conversion power containing high-order harmonics undergoes wave reflection during the transmission process, causing the voltage at the motor end to rise sharply, and its peak voltage can rise to 2-3 times. Has a strong destructive effect on cable insulation and motor insulation, resulting in insulation breakdown
[0011] ④, the existence of high-order harmonics, the structure and laying length of the cable are subject to certain restrictions
[0012] At present, the cables used in frequency conversion systems on the market generally adopt the traditional 3+1, 4-core structure. Due to the asymmetrical balance of the cable structure, the electric field and magnetic field of the cable are always in an unbalanced state, the transmission impedance is high, and the high-order harmonic emission is large. The high-order harmonics in the frequency conversion speed regulation system cannot be effectively suppressed, and the system has serious electromagnetic interference and large motor bearing currents. The frequent problems are tripping (the electrical system is commonly known as "black ghost") and lowering of cables and motors. service life (because the frequency converter, cable and variable frequency motor all run in one system during the transmission process, and affect each other
), which seriously affects the safe operation of the frequency conversion speed control system
Method used
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[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.
[0028] Such as figure 1 As shown, a frequency conversion cable capable of suppressing higher harmonics includes a cable core and a cable outer layer wrapped outside the cable inner core. The cable core includes a three-phase main line insulated wire 1 and a ground wire 2. The three-phase The insulated wires of the main line are distributed on a circle with a phase angle of 120°, and the ground wires are divided into three equal parts, and are distributed around the insulated wires of the three-phase main line at the same circle center as the insulated wires of the three-phase main line at a phase angle of 120°. The long-term stability and reliability of the cable structure is realized by optimizing the ratio of the laying distance and making ...
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The invention discloses a frequency conversion cable used capable of restraining higher harmonic. The frequency conversion cable comprises a cable core and a cable outer layer which coats a cable inner core, wherein the cable core comprises three-phase main line insulated wires and ground wires; and the three-phase main line insulated wires are distributed into a circle at a 120 degrees phase angle, the ground wires are divided into three equal parts which are distributed around the three-phase main line insulated wires and arranged into a circle with the same centre with the circle of three-phase main line insulated wires in the 120 degrees phasing angle manner. The frequency conversion cable provided by the invention has the advantages that electric fields are distributed evenly, and the capacitance current of the frequency conversion cable and the induced voltage of a shielding layer are dropped to the minimum; and the loss in the electrical energy transmission is reduced to the minimum, and the current-carrying capacity of the cable and the safe operation can be protected effectively; and the higher harmonic in a frequency conversion output power supply is restrained to the greatest extent, the bearing current of a motor and each driving part are greatly reduced, thereby prolonging the service life of the motor and equipment.
Description
technical field [0001] The invention relates to a frequency conversion cable, in particular to a frequency conversion cable capable of suppressing high-order harmonics. Background technique [0002] With the rapid development of microcomputer technology, the rapid development of modern power electronic technology and the great progress of modern speed control theory, the frequency converter, as a kind of intelligent speed control "component", is widely used for its multi-purpose, high reliability and obvious energy-saving effect. It is widely used in various large-scale automated production lines and various motor controls. Such as: steel rolling, petrochemical, paper, printing and dyeing, port loading and unloading and mechanical processing and other production lines. [0003] The application of frequency conversion technology in the speed control system is particularly extensive and prominent, because the frequency conversion speed control obviously has the following adva...
Claims
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IPC IPC(8): H01B9/02
Inventor 鲁学姚秀艳赵飞
Owner SHANGHAI MORN ELECTRIC EQUIPMENT CO LTD