[introduction]Power source of switch leaving a line (SMPS) is the classical product that is changeover of power source of electrified wire netting direct current source according to terminal load. Normally, power source of this kind of switch includes two changeover form, to achieve taller efficiency, the mains switch with need to use property better or implement different control strategy. In addition, it is very important also that according to particular case choice more appropriate develop attacks. This systematic program guideline concerns the introduction the ABC of SMPS leaving a line, and Ansenmei (the handpick product of Onsemi) and solution. The article is the first part, introduce the emphasis systematic utility, system information of description of implementation, system, market and trend.

Power source of switch leaving a line (SMPS) is the classical product that is changeover of power source of electrified wire netting direct current source according to terminal load. Normally, power source of this kind of switch includes two changeover form, to achieve taller efficiency, the mains switch with need to use property better or implement different control strategy. In addition, it is very important also that according to particular case choice more appropriate develop attacks. This systematic program guideline concerns the introduction the ABC of SMPS leaving a line, and Ansenmei (the handpick product of Onsemi) and solution. The article is the first part, introduce the emphasis systematic utility, system information of description of implementation, system, market and trend.

Systematic utility

Since last centuries, SMPS leaving a line suffers fully all the time fix eyes upon, occur frequently studies related, apply extensively in the square field surface of daily life. SMPS leaving a line is to point to commonly contain segregation transformer and by the switch power source of power supply of electrified wire netting, suitable scope covers the charger of notebook computer battery from 65W, the device of power source of data center server to thousands of tile.

Product of semiconductor of broad forbidden band emerges in endlessly, this makes a manufacturer OK use new develop to attack to optimize efficiency, dimension and compositive level according to actual condition proper motion. The controller of new design still conduces to enhance systematic security, reduce power comsumption and improve performance.

To realize the whole world ” 0 carbon ” target, SMPS must satisfy rigidder efficiency standard, reduce the sources of energy as far as possible to use up discharge with carbon. For example, to promote energy-saving decrease a platoon, european Union executive board is new the DoE VI of the ministry is opposite issuance CoC V5 and American the sources of energy to be fully loaded with and carry gently / the requirement that the power loss when carrying for nothing and efficiency raised to make clear.

The system comes true

Reference of LLC PSU of ＋ of PFC of 3kw totem pole is designed

Typical SMPS leaving a line

Systematic description

1.Standard

Basically have 3 kinds of levels at present, include safe level and radiation level among them. At present the second edition of newest castigatory IEC 62368-1 attributes safe level, made clear the definition of the concept such as insulation, segregation, clearance, distance climbing report among them. And IEC 61000-3-2 is level of an international radiation, arrive 40 times from the 2nd harmonic through the regulation the maximum of harmonic electric current of harmonic will restrict power source voltage lack fidelity. This standard applies to rated electric current not to exceed the equipment of 16A, rated electric current is more than the equipment of 16A to should abide by IEC 61000-3-12.

To promote energy-saving decrease a platoon, world each district drafted relevant code standard, for example the energy-saving and relevant product of the astral attestation of the code that commission of American California energy drafts, the sources of energy and European Union (ErP) instruction. American energy department (DoE) is aimed at wall hung or exterior power source released desktop type to classification one set standard, among them Level VI is newest and the rigiddest standard; At the same time the science of European committee and knowledge serve an orgnaization ” associated research center ” made an European Union exterior power source is supplied implement (EPS) code of conduct (CoC) .

Still have 80 PLUS in addition? Plan, this plan devotes oneself to to drive in 20% to 100% load the condition issues implementation 80% or taller efficiency, come true below 100% laden conditions 0.9 or higher power factor, its are highest grade (namely ” 80+ titanium gold ” standard) regulation, when 20% load efficiency should be achieved at least 92% , when 100% load efficiency should be achieved at least 94% .

2.Power factor is corrective

PFC (power factor is corrective) the crucial component that is power source leaving a line. The main task of PFC is have plastic to inputting electric current and reduce electric current of high frequency harmonic, former and OK rise from advocate the real power that power source gets, and latter can decrease with distribution, generate electricity the related important equipment loss in reaching a process and cost. THD (total harmonic is lack fidelity) the important method that is quality of electric current of road of definite system central line, often regard power as factor replace index to use. Another of PFC class fundamental value depends on can offerring stable dc to output voltage, the converter of segregation type DC-DC that can be sequel so offers the dc with narrower range to input, optimize integral design thereby.

3.DC-DC class

The action of DC-DC class is to pass segregation transformer and PWM or syntonic converter, the input of certain limits voltage changes the dc that needs for place to export voltage and electricity. The crucial challenge of DC-DC class depends on the design of magnetism component. For example, hasten skin effect and proximity effect can cause occurrence the circular movement of a fluid of high frequency transformer, affect the choice of magnetism core material, cause magnetism core loss and cupreous caustic to wait.

4.Electric current controls mode

Here is necessary to review classic work mode, because working mode affects the choice that develop attacks not only, return the design that can affect whole system. CCM (guide continuously a mode) offer exceed low peak value and Rms electric current, because this is used morely at power level taller application. Below CCM, ripple of inductance electric current is lesser, but MOSFET can guide when connecting, put through in step up diode. So we need to use low Trr diode to avoid MOSFET to guide big loss and stress had arisen when connecting. CrM (critical guide a mode) suit application of low power comsumption very much.

Here mode falls, inductance electric current can be in achieve 0 hind begin next cycle, and frequency is met follow circuit voltage and laden condition change and change. The one big advantage of CrM is comparing stability substantially at voltaic annulus road and do not need brae compensation. In addition, inductance electric current falls in every periodic metropolis to 0, the diode when closing so won’t arise to recover loss reversely, the step up diode that considers use cheaper also won’t have caustic property. Same, MOSFET can guide below low voltage, reduce switch loss thereby.

Be in in the system normally when carrying gently, crM/CCM switch arrives DCM (intermittent guide a mode) , in order to ensure higher power factor, because frequency has been in near 0 o’clock,restrain lift considerably and produce EMI.

FCCrM (frequency Qian critical guide a mode) it is a kind of method that Ansenmeidi gives, the switch frequency that is used at restricting CrM circuit is patulous. Be in when converter carry gently and / or when circuit voltage moves near 0 o’clock too, qian of the biggest frequency switch of can compulsive system arrives DCM. If do not use such circuit, crM switch frequency will exceed Qian upper limit, bring about switch loss to increase. Still need to add a circuit to compensate the dead band time that DCM produces right now, make circuit electric current maintains correct weaveform.

Market information and trend

1.Semiconductor of broad forbidden band

Parts of an apparatus of broad forbidden band is turning production in batch, a lot of companies also are rolled out subsequently (or be about to roll out) the SMPS that is based on SiC/GaN. SiC/GaN material holds concurrently rehabilitate property reversely voltage of outstanding, job reachs exceedingly good, hot property temperature is more advanced and a lot of the advantage is characteristic, can let new system raise frequency to lead dimension of contractible PCB, even need not carbon fin or undertake enforcing coming loose heating up. But high frequency rate may be brought too radiation, strong wait for potential problem, so we must the design with new research and development.

2.Compositive

Can save PCB space and reduce exterior and passive component, can increase power density and installation flexibility thereby. For example, gaN HEMT is medium low power power supply (Pout ＜ 1500W) popular option, can reduce the size of end item considerably. When Dv/dt may exceed 100V/ns, we need to reduce parasitism inductance. Mix GaN HEMT driver is compositive in same the inductance that down-lead and PCB can reduce to cause in enclosing, acquire better switch property thereby.

3.New develop attacks can improve efficiency

Totem pole PFC reduces the loss that causes by rectification bridge, it is consequently in product of high power density, it is to compare the PFC develop with odd better step up to attack. Nowadays, LLC changes by right of wider soft switch range, whole load the narrower frequency range in the process and lesser circular electric current, the actor that in becoming, high power uses chooses DC-DC develop to attack. Semiconductor of broad forbidden band attacks in these new develop in producing crucial effect, and controller of intelligent low power comsumption is to affect another efficient main factor.

Article origin: Ansenmei

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