Rectification diode (Rectifier Diode) a kind of semiconductor device that is used at be alternating current change dc. The character with the mainest diode is only way conductivity. In circuit, electric current can be flowed into from the anode of diode only, negative pole is poured out of. Normally it includes form of a PN, have positive electrode and negative pole two terminal. Its structure is shown like plan institute. Of P area carry stream child it is hole, of N area carry stream child it is an electron, a certain base is formed in P area and N interval. Extra voltage makes P area is relative to N area when voltage, base is reduced, base arises near two side store carry stream child, can carry big electricity, have small voltage drop (typical cost is 0.7V) , call to on-state. If increase contrary tension, make a base increase, can bear tall retrorse voltage, had shed very small retrorse electric current (weigh retrorse leakage current) , call retrorse block to decide position.

 

Rectification diode has apparent one-way conductivity. Rectification diode can use semiconductor germanium or the material such as silicon is made. The puncture voltage of silicon commutate diode is tall, retrorse leakage current is small, high temperature capability is good. Normally diode of high-pressured high-power commutate is used high pure monocrystalline silicon is made (impure relatively a long time is easy and retrorse puncture) . The knot area of this kind of parts of an apparatus is larger, can carry bigger electricity (can amount to on 1000 how) , but working frequency is not tall, it is commonly under a few conspicuous. Rectification diode basically uses half at all sorts of low frequency to work galvanic way, if need,achieve complete wave commutate to need to be used into rectification bridge repeatedly.

 

Rectification diode is chosen
 

 

Rectification diode is plane silicon detector commonly, use in circuit of all sorts of power source commutate.

 

When choosing rectification diode, basically should consider its electric current of electric current of the biggest commutate, the biggest retrorse job, end frequency and restore the parameter such as time reversely.

 

The rectification diode that uses in circuit of regulated power supply of common series connection, not tall to ending to restore time of frequency to ask reversely, the rectification diode that should choose electric current of the biggest commutate and electric current of the biggest retrorse job to accord with a requirement according to the requirement of circuit only can. For example, 1N series, 2CZ series, RLR series.

 

The rectification circuit of switch regulated power supply and the rectification diode that pulse uses in rectification circuit, should choose working frequency taller, retrorse restore the rectification diode with shorter time (for example RU series, EU series, V series, 1SR series) or the alternative is sharp restore diode. Still have diode of commutate of a kind of Xiao Te radical.

 

Rectification diode is characteristic
 

 

Rectification diode is the one-way and electric character that uses PN form, turn alternating current into pulsatile dc. Rectification diode leakage current is bigger, majority uses the diode that makings of surface contact sex encloses. Additional, the parameter of rectification diode is divided in front outside introducing a few, still have electricity of the biggest commutate, it is the value of the biggest electric current that the working place that shows rectification diode is long allows to pass. It is the main parameter of rectification diode, it is the main basis that option uses rectification diode.

 

Rectification diode is commonly used parameter

(1) IF of electric current of the biggest average commutate: What when showing diode permanent worker is made, allow to pass is the biggest to average electric current. The knot area that this electric current writtens guarantee by PN and medicinal powder hot condition decision. The average electric current that when using, should notice to pass diode cannot be more than this value, should satisfy medicinal powder hot condition. For example the IF of 1N4000 series diode is 1A.

 

(2) VR of voltage of highest and retrorse job: Point to diode the biggest retrorse voltage that two end allow to bring to bear on. If be more than this value, retrorse electric current (IR) leap, the one-way conductivity of diode is destroyed, cause retrorse breakdown thereby. Take retrorse puncture voltage normally (VB) the half serves as (VR) . For example the VR of 1N4001 is 50V, 1N4002-1n4006 is 100V, 200V, 400V, 600V and 800V respectively, the VR of 1N4007 is 1000V

 

(3) IR of the biggest retrorse electric current: It is the retrorse electric current that diode allows to had flowed below voltage of highest and retrorse job, this parameter mirrorred the stand or fall of function of report of diode only guide. Value of this electric current is accordingly less, show diode quality has been jumped over.

 

(4) puncture voltage VB: Show diode is retrorse the voltage value that volt-ampere character curve curves a dot quickly. When be soft character reversely, show the voltage that gives condition of retrorse leakage current to fall is worth.

 

(5) Fm of top job frequency: It is the top job frequency that diode issues in normal circumstance. The knot capacitance that basically writtens guarantee by PN and diffuse capacitance decision, if working frequency exceeds Fm, criterion function general cannot reflect the one-way electric conduction of diode well. For example the Fm of 1N4000 series diode is 3kHz. Have additionally fast the commutate that restores diode to lead taller alternating current with Yu Pin, if switch power source is medium.

 

(6) restore time Trr reversely: Show what falling to electric current and voltage of the biggest retrorse transient state is the load in the regulation, retrorse restore time.

 

(7) CO of capacitance of 0 bias voltage: Point to diode two upright voltage are zero hour, diffuse the capacity the sum of capacitance and knot capacitance. Notable is, as a result of the limitation of workmanship, although the diode of same type the disperse sex of its parameter is very big also. The parameter that gives out in manual often is a limits, if check conditional change, corresponding parameter also can produce change, the IR that measures so that model of 1N5200 series silicon seals rectification diode when 25°C for example is less than 10uA, and turn into in the IR when 100°C be less than 500uA.

 

Reason of rectification diode attaint

(1) prevent not do one’s best of safeguard of thunder, overvoltage. Rectification device was not installed prevent protector of thunder, overvoltage, although was installed,prevent protector of thunder, overvoltage, but its job is fluky, damage rectification is in charge of because of be struck by lightning or overvoltage.

 

(2) moving condition is abominable. The generation set of indirect drive, the compare computation because of rotate speed incorrect or two leather belt dish the compare requirement of the diameter than according with rotate speed, make the dynamo is in high rotate speed for a long time next moving, and rectification canal is in the job below taller voltage for a long time also, make rectification canal quicken ageing, be damaged by premature puncture.

 

(3) moving management owes beautiful. Be on duty moving staff job is irresponsible, the change to outside bear (came at 0 o’clock in the late night especially the following day in the morning between 6 o’clock) do not understand, or be happened to swing bear trouble when the outside, moving personnel did not undertake corresponding operation is handled in time, produce overvoltage and provide rectification puncture damage.

 

(4) equipment is installed or make quality close nevertheless. Because generation set is in for a long time,move in bigger vibration, under the outside force interference that makes rectification canal also is in this one vibration; At the same time as a result of discretion of generation set rotate speed, make rectification is in charge of susceptive job voltage also subsequently ignore tall ignore low-lying change, quickened the ageing that rectification is in charge of, attaint greatly so.

 

(5) model of rectification canal norms nots agree with. Change the pipe that the fault when new commutate is in charge of does not accord with working parameter the requirement is changed or wiring mistake, cause rectification to provide puncture damage.

 

(6) rectification canal safety makes rich the quantity slants small. The overvoltage that rectification is in charge of, cross voltaic safety to make rich the quantity slants small, the overvoltage that in making rectification canal bears not to have dynamo excitation return, happens or the assault that cross peak value of voltaic transient process and attaint.

 

Era changes rectification diode

After rectification diode damages, can use the rectification diode that is the same as model or parameter era changes diode of commutate of identical other model.

 

Normally, tall compression is worth (retrorse voltage) rectification diode can take the place of the rectification diode that changes low compression value, and the rectification diode that low compression is worth cannot take the place of the rectification diode that changes tall compression value. The diode with high cost of rectification electric current can take the place of change rectification electric current to be worth low diode, and the diode with low cost of rectification electric current cannot take the place of change rectification electric current to be worth tall diode.

 

Rectification diode checks a method

Tear open the rectification diode in rectifier entirely above all below, with the 100×R of avometer or 1000×R ohmic archives, two when measure rectification diode derivative lines (exchange of head, end is measured each) . If measure gotten resistance twice,differ very big, for example resistance is as high as hundreds of KΩ greatly to arrive infinity, and resistance is little only hundreds of Ω are smaller even, showing this diode is good (the diode except that produced soft puncture) . The resistance that if be measured twice,gets is almost equal, and resistance is very little, explain this diode already was damaged by puncture, cannot use. If be measured twice block value is infinity, explain this diode is already in-house disconnect, cannot use.

 

The character of diode of high frequency commutate and parameter

The rectification diode in switch power source must be had to pressure reduce, the characteristic that restores quickly, still should have enough great output power, can adopt below in order to 3 sort model rectification diode: Restore rectification diode quickly; Super- restore rectification diode quickly; Diode of commutate of Xiao Te radical. Restore quickly and exceed fast restore what rectification diode has moderate to mix taller to voltage drop, its limits is from 0.8 ～ 1.2V. Diode of these two kinds of commutate still has taller cut-off voltage parameter. Accordingly, they are special agree with in small-power, in outputting the circuit of auxiliary power source that voltage controls in 12V, use.

 

As a result of contemporary switch power source working frequency is in 20kHz above, compared with general rectification diode, restore rectification quickly diode and super- restored time Sha Ⅱ what restore rectification diode quickly to reduce nanosecond level reversely, accordingly, improved the efficiency of power source greatly. According to experience, when the choice restores rectification diode quickly, its restore the 1/3 of the rise time that time should be switch transistor at least reversely. Diode of these two kinds of commutate still reduced switch voltage aiguille, and the ripple that this kind of aiguille affects output volts d.c. directly. Additional, although certain call soft restore model the noise of rectification diode is lesser, but restore time their reversely longer, retrorse electric current is bigger also, make consequently switch loss increases, the job that can not satisfy switch power source asks.

 

Restore rectification quickly diode and super- fast whether does radiator need when restoring rectification diode to serve as rectification parts of an apparatus to use in switch power source, want a foundation of circuit most high-power will decide. Usually, the form that these diode permit when make is lukewarm in 175 ℃ , manufacturer home has a technology to explain to this index, calculate in order to carry for going to the architect the biggest output job electric current, voltage and crust temperature. Although diode of commutate of Xiao Te radical is in big falling to voltaic action, its to pressure fall very low also, only 0.4V is controlled, and, as the addition with lukewarm knot, its to pressure fall lower, accordingly, make diode of commutate of Xiao Te radical special in applying to the low voltage that 5V controls to output circuit. It is negligible that Xiaoteji restores time of rectification diode reversely not plan, because this parts of an apparatus is majority carries,flow child semiconductor device, in the switch process of parts of an apparatus, carry without cleared minority stream child the problem of the charge that put store.

 

Diode of commutate of Xiao Te radical has two big drawback: One of, of retrorse cut-off voltage bear ability is inferior, current product is 100V; about secondly, retrorse leakage current is bigger, make this parts of an apparatus easier than the rectification parts of an apparatus of other type be heated puncture. Of course, these defect also can be protected through increasing instantaneous overvoltage circuit and proper control knot are lukewarm will overcome. Expressed the character of diode of typical high speed commutate and parameter.