[introduction]Live in the power source of assistant to loudhailer and intelligence from fast charger and viatic adapter, all sorts of application rely on low power comsumption (under 100 W) AC/DC changeover. Choosing a when power source changes a framework to be nodded basically is its offer 0 voltage switch (the degree of ZVS) , because this is right,function of efficiency, EMI and dependability have major effect. Be not all conventional pictures to attack to be able to realize ZVS, and still attack without a kind of develop at present ZVS can be offerred below light load.

Live in the power source of assistant to loudhailer and intelligence from fast charger and viatic adapter, all sorts of application rely on low power comsumption (under 100 W) AC/DC changeover. Choosing a when power source changes a framework to be nodded basically is its offer 0 voltage switch (the degree of ZVS) , because this is right,function of efficiency, EMI and dependability have major effect. Be not all conventional pictures to attack to be able to realize ZVS, and still attack without a kind of develop at present ZVS can be offerred below light load.

Any communication that insert the electronic equipment of wall electrical outlet to need some kind of form / dc converter will do the inferior level that shed voltage and reduces its equipment place to need. We belong to category of low power comsumption in a lot of modern equipment of family and office discovery, the power of need under 100 W. In fact, besides electric equipment, the mass equipment in our home is possibly by classify equipment of low power comsumption.

Below certain circumstance, for example computer monitor or batteries charger, AC/DC converter will be built-in in product itself. However, a lot of equipment use appropriative exterior power source — include intelligence to live in the computer peripheral equipment such as assistant and disk drive, all these equipment need power supply when use. In addition, AC/DC changeover is the foundation of the adapter that is used at be computer of mobile phone, flat and other portable equipment to charge.

Although the character of low power comsumption of these application may mean efficiency,not be a big question, but the fact is not however such. Using in view of stages of these billion of equipment know exactly about sth, and normally every week 7 days, 24 hours are in put through condition, the influence that because this is used up to the sources of energy,discharges with sequel is tremendous. Accordingly, improve communication / the first job that the efficiency of dc converter is agenda of design of electric power engineer.

The develop that AC/DC of low power comsumption changes attacks and technology

Rated power does not get power factor normally under the converter of low power AC/DC of 75 W corrective (the influence that PFC) asks, because they are right advocate the influence of electrified wire netting is considered as. This simplified to design and reduced component amount — the good choice that this both is solutions of these miniature power source.

Stimulate type develop to attack instead very popular in design of low power comsumption as a result of its versatility, function and simple sex. This kind of develop attacked to had been used 70 old, normally by primary side MOSFET, output (sub) capacitor of rectification diode, output and stimulate transformer instead with etc a few small-sized component are comprised.

Personnel of power source design is sought ceaselessly improve develop to attack, in order to improve efficiency or performance, below good perhaps case both hold concurrently and have. Accordingly, accurate resonance (because can reduce switch loss,QR) stimulates a framework instead and become very popular. This is the leakage that primary MOSFET reduces before guiding through be in promote blood circulation by invigorating vital energy rushs extremely – source pole voltage will come true, this has the effect that reduces peak value electric current and switch frequency, ensure MOSFET is in ” trough ” guide.

The efficiency gain that QR handles basically is below full laden condition implementation. However, the hard switch character that this kind of develop attacks is meant when light load, efficiency wants normally low much.

Through 0 voltage switch (of ZVS) carry out can improve QR to turn over the design that stimulate type further. Stimulate type instead in normal QR in the design, MOSFET is in ” cereal ” in switch, this means leakage source voltage (VDS) is in a value, but do not be certainly 0. Through carrying out ZVS (or soft switch) , VDS falls before MOSFET switch to 0 (is a value not just) , eliminated any jackknife between voltage and electric current thereby, thereby limit ground reduces loss. This still can reduce EMI, this is an additional benefit, can let design personnel to satisfy strict EMC code easily.

Further progress is active clamp stimulate type instead (ACF) develop attacks, it and tradition turn over the design that stimulate type lie differently at, it used the energy that transformer stores in leakage feeling afresh, and these energy can be in originally passive clamp the dissipation in amortize resistor. Offer this to plant to load ” reclaim ” energy can improve converter efficiency, showing reduce during closing the peak value voltage on MOSFET.

In addition, the QR in ACF design ” cereal ” apparently inferior, can realize close ZVS operation normally, reduce switch loss thereby and enhance EMI.

Improve and patulous ZVS function

QuarEgg? Be a kind turn over method of the changeover that stimulate type newly, can raise function, efficiency and dependability further, this is a kind of innovation that develops by Eggtronic model have power source framework only, use technically at the communication under 100 W / dc design. This kind of new framework is showing the size that improved efficiency and reduced the AC/DC converter that is based on ACF and QR to stimulate develop to attack instead normally. Differ with other method, this framework all uses ZVS to move below all laden conditions, offer very flat efficiency curve thereby. The typical efficiency when full load is as high as 95% , the efficiency when light load is as high as 92% , and be in bide his time below mode, the design power comsumption that is based on QuarEgg under 18 MW.

 Graph 1.QuarEgg shows inside whole and laden limits efficiency compares general QR to stimulate converter to be being shown instead rise. Picture by Bodo ‘ S Power Systems is offerred

 Graph 2.QuarEgg develop attacks simplify sketch map. Picture by Bodo ‘ S Power Systems is offerred

Stimulate develop to attack to be compared instead with general QR, new method is in advocate an auxiliary winding was added on transformer, and one flies cross capacitor mixes to be in with joining to configuration MOSFET of the low pressure of low side, low cost. However, cancel clamp of high pressure, high side MOSFET can reduce overall component amount and raise dependability. Advocate the sub side that QuarEgg controller is located in converter, in order to enhance the adjustment to outputting voltage.

Auxiliary MOSFET basically is to regard as enforce actively below all and laden condition advocate a kind of passports that power MOSFET obtains ZVS condition. When converter undertakes switch, sub side controller measures the VDS of primary MOSFET through assisting winding to feel. When every wave crest appears, auxiliary MOSFET guides connect and be opposite discharge of leakage pole node, make VDS turns into 0, ensure thereby advocate the ZVS of MOSFET guides.

Corresponding weaveform is shown as follows.

New method applies to the MOSFET switch parts of an apparatus of all types, include traditional silicon and broadband unoccupied place (WBG) material, for example nitrogen changes gallium (GaN) and carborundum (SiC) . Attack to be compared with traditional ACF and QR develop, the function of the power source converter that is based on QuarEgg got improvement, compare with traditional silicon converter, efficiency raised 7 times, measure is 3 times narrower, and compare with high-powered GaN converter, efficiency raised 3 times, measure is 2 times narrower.

To support a design personnel uses Eggtronic technology, we offerred a series of development board, controller of compositive power source and have magnetic component and detailed technical support only.

 What graph 3.QuarEgg develop attacks is undee. Gules: The VDS of primary MOSFET; Green: Assist the Vg of MOSFET; Blue: The Vg of primary MOSFET. Picture by Bodo ‘ S Power Systems is offerred

Wraparound

To power source of low power AC/DC, charger and adapter, from it is more and more important to carry loaded to capacity efficiency for nothing, because these power source, charger and adapter may be weekly 7 days, everyday 24 hours are in put through condition. So far, a lot of designs are to be based on what had used a few years to stimulate develop to attack instead, although had QR, ACF and ZVS nearly,wait enhance a function.

As Eggtronic EcoVoltas? A of series, quarEgg is changed to provide smaller, more efficient power source only and develop, help an engineer come true function, cost, dimension, weight and but durative target.

Move through active compulsive ZVS, new framework improved efficiency not only, and make efficiency curve becomes even, in order to solve the function when light load not the problem of beautiful. This technology still can reduce package, raise power density and dependability further.

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