In all sorts of industrial control systems, use extensively what wait for device of electric power electron as transducer, systematic electromagnetism is disturbed (EMI) increasingly serious, corresponding interference rejection designs a technology (namely electromagnetism is compatible EMC) has become more and more important. The interference of transducer system can cause hardware damage of the system directly sometimes, sometimes although cannot damage systematic hardware, but often make the systematic program of microprocessor runs out of control, bring about control malfunction, cause equipment and manufacturing accident thereby. Accordingly, the interference rejection capacity that how increases a system and dependability are the serious content that automation unit is developed and cannot ignore in application, also be one of keys that computer control technology applies and popularize. Speak of the interference rejection problem of transducer, want to know way of the origin of interference, transmission above all, take different step in the light of these interference again next. One, the source that transducer violates is the interference that comes from exterior electrified wire netting above all. The harmonic in electrified wire netting disturbs the power supply source that basically carries transducer to disturb transducer. Be like,many harmonic source exists in electrified wire netting all sorts of rectification equipment, hand in voltage of dc exchange equipment, electron to adjust equipment, nonlinear load and lighting equipment. These bear make the voltage in electrified wire netting, electric current produces undee distortion, generate the interference of the harm to equipment of the other in electrified wire netting thereby. The Rebujia after the power supply source of transducer is come from the interference of the alternating current net that is polluted is handled, noise of electrified wire netting can disturb transducer through circuit of power source of electrified wire netting. The interference of power supply source basically has to transducer (1) is pressed too, owe pressure, instantaneous drops report (2) surge, decline (pulse of 3) aiguille voltage (interference of 4) radio frequency. 1, brilliant brake canal is changed shed equipment to be become to the interference of transducer there is brilliant brake canal to change inside power supply network when sorting equipment, because brilliant brake canal always is inside every photograph half-period part-time inside guide, make network report extrude shows sunken mouth easily, weaveform is serious and lack fidelity. Because appear,it makes the rectification circuit of transducer input side possible bigger retrorse reply report press and be damaged, cause input loop breakdown thereby and burn down. 2, the interference of capacitance of electric power compensation to transducer Electricity Department door is right the power factor of the unit that use phone has particular demand, for this, a lot of users are changing electric place uses concentration capacitance compensatory method will raise power factor. In compensating capacitance investment or the transient course that cut, network voltage appears likely very high peak value, its are to may make as a result because the rectification diode of transducer bears exorbitant retrorse voltage and puncture. It is transducer oneself next external the interference of the ministry. The rectification bridge of transducer is nonlinear to electrified wire netting laden, harmonic of generation of electron, electric to the other of same electrified wire netting equipment disturbs the harmonic that it produces. Additionally the inverter of transducer uses PWM technology mostly, should work at switch mode and when making high speed switch, produce noise of many coupling sex. Because this transducer is opposite,source of one electromagnetism interference is for the electron of the other inside the system, electric equipment. In the input of transducer and output electric current, contain part of a lot of Gao Cixie wave. Besides what can form power source not to have work loss inferior outside second harmonic, still have the harmonic part with a lot of very tall frequency. They will go out their energy transmission with all sorts of means, form the interference signal of pair of transducer itself and other equipment. (1) the input side of the undee transducer that inputs electric current is diode commutate and circuit of capacitance filter wave. The line voltage UL that has power supply only apparently is more than capacitor when the volts d.c. UD of two end, the ability in rectification bridge has charging current. Accordingly, charging current always appears around the amplitude value of power source voltage, submit discontinuous bow wave form. It has part of very strong Gao Cixie wave. Concerned data makes clear, 5 harmonic in inputting electric current and 7 harmonic heft of harmonic are the biggest, the 80 ％ that are 50HZ radical wave respectively and 70 ％ . (2) the inversion bridge of the transducer of undee great majority that exports voltage and electricity uses SPWM modulation means, the wave of form of series rectangle form that its output voltage to distributing by sine rule to occupy sky comparing; Because the report of electromotor stator winding is perceptual qualitative, the electric current of stator is close to Yu Zhengxian wave very. But among them as equal as carrier wave frequency harmonic weight still is bigger. 2, the transmission way transducer that disturbs signal can produce the harmonic with greater power, because power is greater, stronger to sex of interference of systematic other equipment, it is consistent that its jam way and track of general electromagnetism interference, main component is conducted (namely circuit coupling) , coupling of electromagnetism radiate, induction. Specific for: ? Qian of male of У of Qi of violet discuss calamity imprints? of of Europe of stitch the sole to the upper of of of Fu of uncut jade of ⒌ Jin is opposite next the noise of electromotor generation electromagnetism of direct drive, make bad news of electric machinery iron and cupreous cost raise; and conducted interference arrives power source, give; of systematic other equipment final transducer through matching sth resembling a net of electrified wire netting to conduct produce inductive coupling to the other circuitry of photograph adjacent, the induction gives interference voltage or electric current. Same, the interference signal inside the system disturbs the regular job of transducer through same way. (1) circuit coupling means travels through power source network namely. Because input electric current to be blame sine wave, when the size when transducer is larger, will make network voltage produces distortion, affect job of other equipment industry, the conducted interference that outputs upright generation at the same time makes the caustic of electric machinery copper of direct drive, iron caustic increases considerably, the movement that affected electric machinery is characteristic. Apparent, the main transmission way that this is signal of interference of transducer input electric current. (2) when the input when transducer or the circuit that export circuit and other equipment suffer inductive coupling kind very nearly, the signal of Gao Cixie wave of transducer will pass means coupling of the induction to go in other equipment. Inductive means has two kinds again: Means of induction of A, electromagnetism, this is the main way of voltaic interference signal; Means of B, electrostatic induction, this is the main way of voltage interference signal. (3) in sky shoot way namely with electromagnetic wave means to the middle of sky shoot, this is the main transmission way of the harmonic heft with very tall frequency. 3, the fundamental of the magnetism of electricity of basis of interference rejection countermeasure of frequency control system, form electromagnetism to disturb (must EMI) have 3 element: ? of low field N is happy south instrument of Xi of Pa of fan of gull of stitch the sole to the upper of predestined relationship of fourth ⒍ of hold tight of huge rock of fan of gull of stitch the sole to the upper of ⒌ of the plinth other fan of gull of stitch the sole to the upper fan of dirty of of cloth of of school of pigheaded F of fan of dirty of of press and smooth of leg of lotus root of fan of dirty of of Mei Bu of take along sth to sb of Buddhist templeput on the brakes of of dirty fan ox washing with watercolors is climbed, it is to point to keep apart interference source and the share that get interference easily from circuit come, make they do not produce electric connection. In system of frequency control transmission, it is power source and amplifier circuit normally between lest,segregation transformer is used on power supply cord conducted interference, power source keeps apart transformer applicable noise to keep apart transformer. 2, the action that sets filter in systematic circuitry is to restrain interference signal to arrive through conducted interference of power supply cord from transducer power source from electromotor. To reduce electromagnetism noise and loss, in transducer output side can install output filter; to be opposite to decrease electrical interference, side can be inputted to install input filter in transducer. If there is sensitive electron facility in circuit, lest,filter of power source noise can be installed on power supply cord conducted interference. In the input of transducer and output circuit, besides afore-mentioned inferior harmonic class status, still have the harmonic electricity with a lot of very tall frequency, they will go out their energy transmission with all sorts of means, form the interference signal of pair of other equipment. Filter is used at weakening the main measure of the harmonic heft with taller frequency namely. What the basis uses the position is different, can divide for: (1) inputs filter to have two kinds again normally: Filter of A, circuitry basically is formed by inductance coil. It is in through increasing line high frequency the impedance below will weaken the harmonic electric current with taller frequency. Filter of B, radiate basically is formed by high frequency capacitor. It sponge frequency very tall, the harmonic part that has radiation energy. (2) outputs filter to also be formed by inductance coil. It weakens the Gao Cixie in exporting electricity effectively wave composition. Not only the effect that has interference rejection, and the add torsion that in can weakening electromotor, by Gao Cixie wave harmonic electric current causes. Output the interference rejection measure of end to transducer, must note the following respect: A, frequency implement output end does not allow to receive capacitor, lest in inversion the canal guides,connect (close) the instant, generation peak value is very great charge (or discharge) electric current, damage inversion canal; When filter of B, output is formed by LC circuit, a side of capacitor is received inside filter, must connect with electromotor side. 3, screen interference source is the most effective method that restrains interference. Normally transducer itself uses iron carapace screen, do not let its electromagnetism disturb leak; to output a line to had better use steel tube screen, when controlling transducer with exterior signal especially, requirement line as far as possible short (it is) of 20m less than commonly, and line uses double core screen, and with main circuit line (AC380V) and control line (AC220V) is completely detached, can put within same tubing or line chamfer anything but, all round the electron is sensitive equipment line also asks screen. To make screen effective, screen is overspread must reliable ground connection. 4, correct ground connection can make the system restrains foreign interference effectively already, can reduce the equipment itself interference to the outside again. In using a system actually, as a result of systematic power source 0 lines (central line) , ground wire (protective ground connection, system ground connection) not ground of screen of system of cent, control (ground of control signal screen and ground of screen of main circuit wire) confused join, reduced systematic stability and reliability greatly. To transducer, advocate the correct ground connection of loop terminal PE(E, G) is to raise transducer to restrain noise ability and the important step that reduce transducer interference, because this is in actual application,must take seriously very much. The cut area of lead of transducer ground connection should not is less than commonly 2. 5mm2, length control is in 20m less than. The ground connection of proposal transducer and dot of ground connection of other power plant are apart, cannot in all. 5, use reactor to lead inferior harmonic heft in the intermediate frequency of input electric current of transducer (the place such as 13 11 7 5 harmonic, harmonic, harmonic, harmonic) the proportion that holds is very tall, they move normally besides what disturb other equipment possibly besides, because they were used up,still do not have result power in great quantities, make the power factor of circuit drops greatly. Reactor is being strung together inside input is the effective method that restrains inferior harmonic electric current. According to wiring position different, basically have the following two kinds: (1) reactor series connection is between the input side of power source and transducer. Its are main the function has: A, through restraining harmonic electric current, raise power factor to (0.
75-0.
85) ; The to transducer concussion of B, surge electric current in weakening input; C, weaken the influence with power source lopsided voltage. (2) dc reactor series connection is between rectification bridge and filter wave capacitor. Its function is singler, weaken the composition of Gao Cixie wave in inputting electric current namely. But increasing power factor respect more effective than communicating reactor, can amount to 0.
95, have a structure simple, volume is minor wait for an advantage. 6, manage wiring disturbs signal to what travel through inductive means, the kind that can carry reasonable wiring will weaken. Specific means has: (1) the power supply cord of equipment and line should measure line of the input that is far from transducer, output; (2) the power supply cord of other equipment and line should avoid parallel of line of the input with transducer, output; 4, the source that conclusion carries the interference in using a process to transducer and the analysis that spread a way, put forward to resolve the real the way to deal with a situation of these problems, the application that goes up in transducer ceaselessly as new technology and new theory, take the EMC requirement of transducer seriously, already became the problem that design of system of frequency control transmission, application must face, also be one of keys of transducer application and promotion. These problem hopeful that transducer exists pass the function of transducer itself and compensation to solve. Industrial spot and social environment rise ceaselessly to the requirement of transducer, those who satisfy real need is true " green " transducer also can come out before long. We believe the EMC problem of transducer can get be settlemented effectively certainly. CNC Milling