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mg kyi thar
11-10-2009, 02:33 PM
power supply အမ်ားစုရွိတ႕ဲအနက္ က်ြန္ေတာ္က ေတာ႕1. liner mode power supply
2. switching mode power supply ကိုသာသိထားပါ တယ္။
ဒီေခါင္းစဥ္ေလးကေတာ႕ electronic သမားတိုင္ သိထားသင္႕တ႕ဲ ေၾကာင္းေလးၿဖစ္ပါတယ္။ circuit တစ္ခုအသက္ရွင္ ေမာင္းႏွင္ႏုိင္ဖိို႕အတြက္ power supply က
အေရးပါ လွပါတယ္။ liner mode power supply ကိုေတာ႕ သိထားပါတယ္။ သို႕ေသာ္ switching mode power supply ကိုေတာ႕ သိပ္မသိေသးလို႕
ရွင္းၿပေစလိုပါတယ္ဗ်ာ။
အားလုံးကိုေလးစားစြာၿဖင္႕ mg kyi thar ///////////////

ခ်စ္ဦး
11-10-2009, 03:36 PM
Switching mode power supply ကို Switched mode power supply ဒါမွမဟုတ္ SMPS လို႔လဲအတိုေကာက္ ေခါ ္လို႔ရပါတယ္။ SMPS ဆိုတာ input voltage ကို pulse signal အေနနဲ႔ ေျပာင္းျပီး Output မွာ Capacitor နဲ႔ Inductor တို႔လို Filtration Devices ေတြနဲ႔ Current နဲ႔ Voltage Ripple ေတြကို စစ္ထုတ္ေပးျပီး လိုအပ္တဲ့ Voltage ေတြကို ထုတ္ေပးတာပါ။
Electronic သမားတစ္ေယာက္ ဆိုရင္ Chopper အေၾကာင္းေတာ့သင္ခဲ့ဖူးမယ္နဲ႔ တူပါတယ္ေနာ္။ Chopper ဆိုတာကလဲ SMPS အမီ်ဳးအစားတစ္မ်ီဳးပါပဲ။ SMPS မွာTopology ေတြအမ်ားၾကီးရွိပါတယ္။ Topology ဆိုတာက SMPS မွာပါ၀င္တဲ့magnetic နဲ႔ Electronic element ေတြ ရဲ႕ အစီအစဥ္ ကြာျခားမွဴေပါ ္မူတည္ျပီးခြဲျခားထားတာပါ။ Topology ေတြကအမ်ားၾကီးရွိပါတယ္။
အဓိကအားျဖင့္ Isolated Converter နဲ႔ Non-Isolated Converter လို႔ခြဲထားပါတယ္။
Isolated Converter က Input Output Voltage ကြာျခားခ်က္မ် ားတဲ့ Converter ေတြမွာ သံုးပါတယ္။
Non-Isolated Converter က I/O Voltage ကြာျခားခ်က္ သိပ္မရွိတဲ့ DC to DC application ေတြမွာ အသံုးမ်ားပါတယ္။
Non-Isolated Converter ေတြကေတာ့
Buck converter, Boost converter, Buck-Boost converter အစရွိသည္ျဖင္ရွိပါတယ္
Isolated converter ေတြကေတာ့
Flyback, Forward, Half Bridge, Push pull နဲ႕ Full Bridge အစရွိသည္ျဖင္ရွိပါတယ္။
အေသးစိတ္ကိုေတာ့ ဆက္ေဆြးေႏြးပါမယ္။

Luminox
11-11-2009, 05:25 PM
Switch mode power supply (SMPS) circuits contain networks of energy storage inductors and capacitors as well as power handling electronic switches and rectifiers. Their particular arrangement is referred to as a topology. There are about a dozen main converter topologies used in practical power design. The table below summarizes and compares electrical features and characteristics of the main switching regulator circuits. This chart is followed by the converter topology selection guide.

TOPOLOGY SELECTION CONSIDERATIONS
. There is no single topology, which is best for all applications. The right SMPS topology for a given application should be selected based on specific requirements for the power supply design including cost, size, time factors, and expected production volume. For example, for low-volume designs, the engineering expenses may be more important than BOM cost. In this case, you may want to choose a straightforward approach in which you are most experienced. For a high-volume production, you'll want to put extra engineering efforts in developing new solutions, minimizing component cost and assembly labor. When the other functional requirements are typical, the power level is usually the main factor that determines the topology. As an illustration, the table below shows the topologies I would recommend for a downstream DC-DC converter in an offline switching power circuit depending on its output power level. This selector guide is given for the power sources with output voltages below 60V running off 120 to 400V DC-link (which is typical for rectified AC input line voltage or the output of a PFC boost). Note, this is just a basic guidance, which is based on the author's personal view.

phoelapyae
11-12-2009, 03:12 AM
က်ေနာ္လဲ မွတ္ထားသေလာက္ ၀င္ေဆြးေႏြးလုိက္ပါတယ္ ...

** Linear Power Supply က stable output voltage ရဖို႕အတြက္ variable resistor တို႕ပါတဲ့ linear regulator ေတြသံုးထားပါတယ္ ...
အဲ့အတြက္ powser loss မ်ားပါတယ္ ... ဒါ့အျပင္ power supply မွာပါတဲ့ transformer ရဲ႕ အရြယ္အစားကလဲ ႀကီးမားပါတယ္ ..
သူက 50Gz နဲ႕ 60 Hz ေလာက္မွာ လုပ္တဲ့အတြက္ low frequecy ျဖစ္လို႕ အရြယ္အစားႀကီးမားပါတယ္ ..

** Switch Mode Power Supply ေတြကေတာ့ FET ေတြနဲ႕ တည္ေဆာက္ထားတဲ့ switching regulator ကုိသံုးထားတဲ့အတြက္ power loss နည္းပါတယ္ ။
Switch Mode ဆုိတဲ့အတိုင္း သူက switch on/off ကုိ သတ္မွတ္ထားတဲ့ frequency အတိုင္းေဆာင္ရြက္ပါတယ္ ။
SMPS ေတြမွာ frequency က 20KHz ေလာက္ လုပ္တဲ့အတြက္ linear power supply နဲ႕ နႈိင္းယွဥ္ရင္ မ်ားပါတယ္ ။
အဲ့အတြက္ transformer ဆုိက္က ေသးပါတယ္ ။ သူက switch အေနနဲ႕ on/off ေဆာင္ရြက္တဲ့အတြက္ power loss က အရမ္းနည္းပါတယ္ ။
power loss နည္းတဲ့အတြက္ heat ထုပ္မႈကလဲ အရမ္းနည္းပါတယ္ ။
ဒါေပမဲ့သူက high frequency ျဖစ္တဲ့အတြက္ electromagnetic radiation ျဖစ္ေပၚတဲ့အတြက္ ပတ္၀န္းက်င္ အီလက္ထေရာနစ္ပစၥည္းေတြကုိ ထိခိုက္ေစပါတယ္ ။
အဲ့အတြက္လဲ သူ႕ကုိ သတၱဳျပားေတြနဲ႕ ဖံုးကာထားေလ့ရွိပါတယ္ ။

Luminox
11-13-2009, 01:22 AM
This is the comparison between linear and switching power supply.

Luminox
11-13-2009, 04:02 PM
These are some ebooks for SMPS.

Switched Mode Power Supply Reference Manual
" http://ifile.it/c1ej5w4/SMPSRM-D.pdf "

Topology Selection
" http://ifile.it/ezuqsfg/Topology.pdf "

Linear and Switching Regulator Fundamentals
" http://ifile.it/uwqvxpg/f4.pdf "

hightechkey
07-10-2010, 02:07 PM
These are some ebooks for SMPS.

Switched Mode Power Supply Reference Manual
" http://ifile.it/c1ej5w4/SMPSRM-D.pdf "

Topology Selection
" http://ifile.it/ezuqsfg/Topology.pdf "

Linear and Switching Regulator Fundamentals
" http://ifile.it/uwqvxpg/f4.pdf "


အစ္ကိုေရ

link ေတြမွာ file မရွိေတာ့ဘူး... ျဖစ္ႏိုင္ရင္ ျပန္တင္ေပးပါဦး.... ကၽြန္ေတာ္လည္း SMPS အေၾကာင္း စိတ္၀င္စားလို႔ပါ... ေနာက္ထပ္ SMPS နဲ႔ ပတ္သတ္တဲ့ အေၾကာင္းအရာေလးေတြ လည္း ေဆြးေႏြးေပး ၾကပါဦး.... Thank....

High Tech Key

hightechkey
07-10-2010, 09:32 PM
Theory of Operation

http://upload.wikimedia.org/wikipedia/en/e/e3/SMPS_Block_Diagram.png

SMPS ရဲ႕ အေျခခံ အလုပ္လုပ္ပံုေလး ပါ... ကၽြန္ေတာ္ ေနာက္ပိုင္း step တစ္ခုခ်င္းစီကို တင္ေပးသြားပါမယ္..

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 09:45 PM
Input rectifier stage

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Rectification.svg/350px-Rectification.svg.png
AC, half-wave and full-wave rectified signals.

If the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 V or 240 V supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230 V AC this would be 330 V DC), as the DC passes through the rectifier stage unchanged. It's however advisable to consult the manual before trying this, though most supplies are quite capable of such operation even though nothing is mentioned in the documentation. However, this type of use may be harmful to the rectifier stage as it will only use half of diodes in the rectifier for the full load. This may result in overheating of these components, and cause them to fail prematurely.

If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 V AC) range and as a straight rectifier when operating on the high voltage (~240 V AC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of DC voltages that will be produced by the rectifier stage. In higher-power SMPSs, some form of automatic range switching may be used.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 09:48 PM
Inverter stage

The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 09:49 PM
Voltage converter and output rectifier

If the output is required to be isolated from the input, as is usually the case in mains power supplies, the inverted AC is used to drive the primary winding of a high-frequency transformer. This converts the voltage up or down to the required output level on its secondary winding. The output transformer in the block diagram serves this purpose.

If a DC output is required, the AC output from the transformer is rectified. For output voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky diodes are commonly used as the rectifier elements; they have the advantages of faster recovery times than silicon diodes (allowing low-loss operation at higher frequencies) and a lower voltage drop when conducting. For even lower output voltages, MOSFETs may be used as synchronous rectifiers; compared to Schottky diodes, these have even lower conducting state voltage drops.

The rectified output is then smoothed by a filter consisting of inductors and capacitors. For higher switching frequencies, components with lower capacitance and inductance are needed.

Simpler, non-isolated power supplies contain an inductor instead of a transformer. This type includes boost converters, buck converters, and the so called buck-boost converters. These belong to the simplest class of single input, single output converters which use one inductor and one active switch. The buck converter reduces the input voltage in direct proportion to the ratio of conductive time to the total switching period, called the duty cycle. For example an ideal buck converter with a 10 V input operating at a 50% duty cycle will produce an average output voltage of 5 V. A feedback control loop is employed to regulate the output voltage by varying the duty cycle to compensate for variations in input voltage. The output voltage of a boost converter is always greater than the input voltage and the buck-boost output voltage is inverted but can be greater than, equal to, or less than the magnitude of its input voltage. There are many variations and extensions to this class of converters but these three form the basis of almost all isolated and non-isolated DC to DC converters. By adding a second inductor the Ćuk and SEPIC converters can be implemented, or, by adding additional active switches, various bridge converters can be realised.

Other types of SMPSs use a capacitor-diode voltage multiplier instead of inductors and transformers. These are mostly used for generating high voltages at low currents (Cockcroft-Walton generator). The low voltage variant is called charge pump.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 09:50 PM
Regulation

A feedback circuit monitors the output voltage and compares it with a reference voltage, which shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may or may not contain an isolation mechanism (such as opto-couplers) to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage.

Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of the transformer or inductor, and assume that the output will be correct. Regulated designs compensate for the parasitic capacitance of the transformer or coil. Monopolar designs also compensate for the magnetic hysteresis of the core.

The feedback circuit needs power to run before it can generate power, so an additional non-switching power-supply for stand-by is added.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 09:51 PM
Advantages and disadvantages

The main advantage of this method is greater efficiency because the switching transistor dissipates little power when it is outside of its active region (i.e., when the transistor acts like a switch and either has a negligible voltage drop across it or a negligible current through it). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.

Very low cost SMPSs may couple electrical switching noise back onto the mains power line, causing interference with A/V equipment connected to the same phase. Non-power-factor-corrected SMPSs also cause harmonic distortion.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

hightechkey
07-10-2010, 10:01 PM
Applications

Switched-mode power supply units (PSUs) in domestic products such as personal computers often have universal inputs, meaning that they can accept power from most mains supplies throughout the world, with rated frequencies from 50 Hz to 60 Hz and voltages from 100 V to 240 V (although a manual voltage range switch may be required). In practice they will operate from a much wider frequency range and often from a DC supply as well.

In 2006, at an Intel Developers Forum, Google engineers proposed the use of a single 12 V supply inside PCs, due to the high efficiency of switch mode supplies directly on the PCB.[15]

Most modern desktop and laptop computers also have a voltage regulator module—a DC–DC converter on the motherboard to step down the voltage from the power supply or the battery to the CPU core voltage, which is as low as 0.8 V for a low voltage CPU to 1.2–1.5 V for a desktop CPU as of 2007. Some motherboards have a setting in the BIOS that allows overclockers to set a new CPU core voltage; other motherboards support dynamic voltage scaling which constantly adjust the CPU core voltage. Most laptop computers also have a DC–AC converter to step up the voltage from the battery to drive a CCFL backlight in the flat-screen monitor, which typically requires around 1 kVRMS.[16]

Due to their high volumes mobile phone chargers have always been particularly cost sensitive. The first chargers were linear power supplies but they quickly moved to the cost effective ringing choke converter (RCC) SMPS topology, when new levels of efficiency were required. Recently the demand for even lower no load power requirements in the application has meant that flyback topology is being used more widely; primary side sensing flyback controllers are also helping to cut the bill of materials (BOM) by removing secondary-side sensing components such as optocouplers.

Where integration of capacitors for stabilization and batteries as a energy storage or hum and interference needs to be avoided in the power distribution, SMPS may be essential for efficient conversion of electric DC energy. For AC applications where frequency and voltage can't be produced by the primary source an SMPS may be essential as well. Applications may be found in the automobile industry where ordinary trucks uses nominal 24 VDC but may need 12 VDC. Ordinary cars use nominal 12 VDC and may need to convert this to drive equipment. In industrial settings, DC supply is sometimes chosen to avoid hum and interference and ease the integration of capacitors and batteries used to buffer the voltage that makes SMPS essential.

en.wikipedia.org မွ ကူးယူေဖာ္ျပပါသည္....

ေဇဦးေမာင္
07-18-2010, 10:34 PM
power supply ေခါင္းစဥ္ေအာက္မွာ တစ္ခုေလာက္၀င္ေမးခ်င္ပါတယ္ ခင္ဗ်ာ ... design and implementation of dc power supply and dc power management for industrial application ဆုိတဲ့ thesis ေခါင္းစဥ္ကို .. လုပ္ရမဲ့ လမ္းေၾကာင္းေလး .. ျပည့္ျပည့္စံုစံုသိခ်င္ပါတယ္ခင္ဗ်ာ ... thesis ရဲ႕ ရည္ရြယ္ခ်က္တစ္ခုျဖစ္တဲ့ electric utility bills ကို reduce လုပ္ဖုိ႔ဆုိရင္ ... AC power management ကသာ အဓိကမဟုတ္လားခင္ဗ်ာ .. အခု ေခါင္းစဥ္က ... dc power supply ကို management လုပ္မယ္ဆုိေတာ့ ဘယ္လုိၾကီးလဲဗ်ာ ... ေဆြးေႏြးးေပးပါအံုးေနာ္ ....

ေအ၇ာ
07-19-2010, 11:58 AM
power supply ေခါင္းစဥ္ေအာက္မွာ တစ္ခုေလာက္၀င္ေမးခ်င္ပါတယ္ ခင္ဗ်ာ ... design and implementation of dc power supply and dc power management for industrial application ဆုိတဲ့ thesis ေခါင္းစဥ္ကို .. လုပ္ရမဲ့ လမ္းေၾကာင္းေလး .. ျပည့္ျပည့္စံုစံုသိခ်င္ပါတယ္ခင္ဗ်ာ ... thesis ရဲ႕ ရည္ရြယ္ခ်က္တစ္ခုျဖစ္တဲ့ electric utility bills ကို reduce လုပ္ဖုိ႔ဆုိရင္ ... AC power management ကသာ အဓိကမဟုတ္လားခင္ဗ်ာ .. အခု ေခါင္းစဥ္က ... dc power supply ကို management လုပ္မယ္ဆုိေတာ့ ဘယ္လုိၾကီးလဲဗ်ာ ... ေဆြးေႏြးးေပးပါအံုးေနာ္ ....

Design အပိုင္းက DC Power Supply ကို စြမ္းအင္ေခၽြတာေရးျဖစ္ေအာင္ တည္ေဆာက္ဖို႕ျဖစ္ၿပီး
ေနာက္တစ္ခ်က္အေနနဲ႕ DC Power အသံုးမ်ားတဲ့ စက္မႈလုပ္ငန္းခြင္ေတြမွာ Power management အပိုင္းက ထပ္ဆင့္ေလ့လာတင္ျပေပးရမယ္လို႕ ယူဆပါတယ္။
DC Power ကိုပဲ မေတာ္တဆ ျပတ္ေတာက္သြားတာခြင့္မျပဳႏိုင္ဘူးဆိုလွ်င္ စီမံေပးရတာေတြရွိဦးမယ္လို႕ထင္တာပါ။
AC power management မွာေတာ့ Total Load Power ထက္ ေမာင္းႏွင္ေပးထားတဲ့ Generator ေတြရဲ႕ Power ထုတ္ေပးႏိုင္စြမ္းက ပိုမိုမ်ားျပားလြန္းေနတယ္ဆိုလွ်င္ စက္အခ်ဳိ႕ကို စြမ္းအင္ေခၽြတာတဲ့စနစ္က အလိုအေလ်ာက္ Shut down ဆဲြခ်ေပးေစတာမ်ဳိးေတြပါ၀င္ပါတယ္။
Load increase ျဖစ္ဖို႕ေတာင္းဆိုလာလွ်င္္လည္း Standby Generator ေတြက အလိုအေလ်ာက္ Run လာၿပီး အလိုအေလ်ာက္ပဲ မူလစနစ္ထဲမွာပူးေပါင္းပါ၀င္လာရပါတယ္။

အဲဒါေတြကို နမူနာယူၿပီး DC Power ေတြသံုးၾကတဲ့စနစ္မွာ လက္ရွိဘာေတြလုပ္ေလ့ရွိလဲ ေနာင္ကိုဘယ္လိုပိုျပည့္စံုေကာင္းမြန္ေအာင္လုပ္ေပးႏိုင္ဦးမလဲစတာေတြ ပါ၀င္သင့္တယ္လို႔ မွန္းဆအႀကံျပဳလိုပါတယ္။

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