Switch power source introduces

The power supply system of option market Chinese style of means of 1 power supply is outputted each the deviation between and cause as a result of the differring of transmission distance pressed difference to reduce power supply quality, and power supply of power source of applied only station, when power source malfunctions the likelihood brings about a system to break down. Distributed power supply system stands by load because of power supply unit, improved trends to answer character, power supply quality is good, transmission loss is small, efficiency is tall, managing the sources of energy, reliability is high, ＋ of easy composition N 1 redundant power supply system, it is easy that patulous power also is compared relatively. Use distributed power supply system to be able to satisfy the requirement of high reliability equipment so. 2.

The select switch power source that 2 circuit develop attacks uses sheet to stimulate type, Chan Duan to stimulate type, double-barreled to stimulating type, double sheet rightly instead rightly commonly type, double stimulating 8 kinds of develop such as type, push-pull type, half bridge, complete bridge to attack. Sheet stimulates type, Chan Duan to stimulate type, double sheet to stimulate switch of type, push-pull to be in charge of rightly instead rightly bear press in above of double input voltage, if press 60 ％ to fall,the forehead is used, make switch is in charge of not easy type selecting. In push-pull and complete bridge develop the likelihood in attacking appears one-way slant magnetism is saturated, make switch provides damage, and because half bridge circuit is had fight lopsided ability automatically, won't appear so this problem. Double-barreled is stimulating type and canal of switch of half bridge circuit bear press what be power source only voltage of the biggest input, although press 60 ％ to fall,the forehead is used, it is easier also to choose switch to be in charge of. Choose develop of these two kinds of circuit to attack commonly on high reliability project. 2.

In the power source of the in choosing to be in small-power with 3 politic control, control of electric current PWM is the method that a large number of adoption, it relatively voltage control be like next advantages: Pursue restriction of periodic electric current, faster than voltage control, won't flow because of passing and make switch provides damage, reduce the protection of overload and short circuit greatly; Regulation of admirable voltage of electrified wire netting; The transient state of fast is answered; Annulus road is stable, easy compensation; Control of ripple comparing voltage small much. Manufacturing practice shows electric current is controlled model the output ripple of 50W switch power source is controlled in 25mV, control of far excel voltage. The limitation of hard switch technology because of switch loss, switch frequency is commonly under 350kHz, soft switch technology is applied resonance principle, make switch parts of an apparatus is connected below 0 voltage or condition of 0 electric current, implementation switch loss is 0, can raise switch frequency megahertz grade level thereby, this kind of transformer that uses soft switch technology is integrated PWM transformer is harmonious brace up the advantage with both transformer, be close to good character, be like control of low switch loss, constant frequency, appropriate Chu Nengyuan dimension, wider control range and laden limits, but this technology basically applies at high-power power source, in still give priority to with PWM technology in small-power power source. 2.

Of 4 yuan of parts of an apparatus because,choose yuan the dependability that parts of an apparatus decided power source directly, so yuan of parts of an apparatus it is very important to choose. Yuan the invalidation of parts of an apparatus basically is in centrally the following 4 respects: (the be no longer in force that problem of quality of problem of 1) production quality creates and working stress have nothing to do. Of off quality can try through examining strictly eliminate, the mature product that selects manufacturer home surely should be chosen when project application, do not allow to use the product that did not pass attestation. (2) yuan problem of dependability of parts of an apparatus yuan problem of dependability of parts of an apparatus namely the problem of basic failure rate, this is the invalidation of a kind of random nature, with the distinction of quality problem the failure rate that is yuan of parts of an apparatus depends on working stress level. Below certain stress level, yuan the failure rate of parts of an apparatus can drop greatly. Do not accord with yuan of parts of an apparatus of use requirement for eliminate, include electric parameter unqualified, sealed function unqualified, exterior unqualified, stability difference, early failure, should have screening test, this is experiment of a kind of nondestructive. Can make through choosing failure rate reduces yuan of parts of an apparatus 1 ～ 2 amounts class, of course screening test cost (time and charge) very big, but safeguard of integrated maintenance, logistics, whole couplet tries etc still is economical, development cycle also won't be lengthened. Power source facility is main the screening test of yuan of parts of an apparatus asks commonly: ① resistor undertakes by technical condition below room temperature 100 ％ check, eliminate reject. Container of ② general electrify presses technical condition to undertake 100 ％ check below room temperature, eliminate reject. ③ receives plug-in unit to sample by technical condition detect all sorts of parameter. ④ semiconductor device undertakes filtration by the following program: Computational eliminate answers to lead × of Q=(n/N) of 　 of 　 of Q 　 　 after high low temperature of → of keep in storage of → high temperature measuring to pound high temperature of → of ageing of → electric power to check → low temperature to check → normal temperature to check 　 　 to choose an end at the beginning of visual inspection → in type of 　 of 100% 　 　 : N -- suffer sample to taste gross; N -- by the sample number of eliminate; If Q exceeds the upper limit value that the standard provides, approve yuan of parts of an apparatus to forbid to go up entirely originally machine, press concerned regulation processing. When according with a standard to set, make yuan of parts of an apparatus or appliance that chooses qualification lacquer dot tag, use for outfit machine into special storeroom next. (3) design problem is appropriate ground chooses yuan of appropriate parts of an apparatus above all: ① chooses silicon semiconductor device as far as possible, be used less or need not germanium semiconductor device. ② uses integrated circuit more, reduce the number of schism parts of an apparatus. ③ switch canal chooses MOSFET to be able to simplify drive circuit, reduce loss. Canal of ④ output commutate collects appliance to have as far as possible soft the diode that restores character. ⑤ should choose a metal to enclose, pottery and porcelain is enclosed, the parts of an apparatus that glass encloses. Prohibit choosing plastic enclosed parts of an apparatus. ⑥ integrated circuit must be be tasted one kind or accord with MIL - M - 38510, MIL - S - 19500 standards B - of grade of 1 above quality army article. When ⑦ is designed use relay less as far as possible, the sealed relay with good contact should be chosen when be necessary truly. ⑧ in principle does not choose potentiometer, must withhold should undertake originallying sealing handling. The space that ⑨ absorbs capacitor and switch canal and output commutate canal ought to very close, because had shed high frequency electric current, reason Yi Sheng is lukewarm, ask these capacitor have high frequency small loss and high temperature resistant character so. Below moisture and saline mist environment, aluminium electroanalysises capacitance can produce crust to corrode, capacity drift, leakage current increases wait for a circumstance, mix in ship vessel so damp environment, had better not electroanalysis with aluminium capacitance. Because suffer when dimensional particle bombard, electrolyte can be decomposed, so aluminium electroanalysises in the power source that capacitance also does not apply to spaceflight electron equipment. Tantalum electroanalysises capacitance temperature and frequency character are better, be able to bear or endure on any account is lukewarm, store time is long, function is stable and reliable, but tantalum electroanalysises heavier, cubage compares capacitance low, do not be able to bear or endure to be pressed instead, high-pressured breed (> 125V) less, price is high. About falling the forehead designs: Electron yuan the basic failure rate of parts of an apparatus depends on working stress (include the) such as report, temperature, oscillatory, concussion, frequency, speed, collision. Outside removing yuan of parts of an apparatus or appliance of invalidation of individual low stress, other all is behaved jump over for working stress tall, failure rate jumps over tall character. To make the failure rate of yuan of parts of an apparatus is reduced, want to undertake the forehead is designed falling when circuit is designed so. Fall frontal degree, outside dividing dependability, still need to consider the factor such as bulk, weight, cost. Yuan of different parts of an apparatus fall frontal standard also differs, practice makes clear, major electron yuan the basic failure rate of parts of an apparatus depends on electric stress and temperature, fall consequently the forehead basically also is to control these two kinds of stress, it is switch power source below commonly used of yuan of parts of an apparatus fall frontal coefficient: The power of ① resistor falls frontal coefficient is in 0.

1 ～ 0.

5 between. The power of ② diode falls frontal coefficient is in 0.

4 the following, retrorse compression is in 0.

5 the following. ③ glow diode. CNC Milling CNC Machining