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Načrtovanje 300 W digitalnega laboratorijskega usmernika
ID MIKEC, JOŽE (Author), ID Križaj, Dejan (Mentor) More about this mentor... This link opens in a new window

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PID: 20.500.12556/rul/f909364f-09dc-409a-bfdc-24cfadcc47b2

Abstract
Diplomsko delo z naslovom digitalni laboratorijski usmernik popelje bralca skozi načrtovanje in služi kot vodnik za izdelavo natančnega variabilnega usmernika, ki je zmožen nastavitve napetosti od 0-30 V in toka od 0-5 A z inkrementi 10 mA/mV. V začetku najprej predstavim težave pri načrtovanju vezij in navedem ukrepe, s katerimi se teh težav izognemo. Nato na kratko opišem načine za izdelavo električnih shem in na koncu realizacijo le-teh na tiskanem vezju. Glavni del diplome zajema predvsem načrtovanje in realizacijo analognega usmerniškega vezja, dotakne pa se tudi povezave mikroprocesorja z analognim krmiljenim delom vezja in vhodnim uporabniškim vmesnikom. Analogni del je sestavljen iz treh poglavji. Prvo poglavje opisuje izvedbo napajanja in pred-regulacije, kjer je opisano delovanje in osnovni izračuni za realizacijo usmerniškega vezja. To se sestoji iz transformatorja, usmerniškega mostiča in gladilnih kondenzatorjev. Pred-regulacija je namenjena izboljševanju učinkovitosti in to s preklopnim regulatorjem tudi dosega, saj taki regulatorji dosegajo veliko boljše izkoristke, tudi do 90 %, kar je veliko več, kot dosegajo linearni regulatorji ali druge implementacije pretvorbe napetosti. V tem podpoglavju se dotaknem načrtovanja preklopnega regulatorja, predstavim način uporabljen za reguliranje in podam formule za izračun in izbiro zunanjih elementov pred-regulatorja. V četrtem poglavju je opisano analogno krmiljenje, opisane so metode krmiljenja izhoda in implementacija operacijskih ojačevalnikov za enostavno kontrolo z mikroprocesorjem. Posebnost v tem načrtu je merjenje toka, saj je izvedeno s pomočjo Hallovega senzorja. Opisujem pa tudi napajanje, ki je potrebno za delovanje aktivnih naprav v krmiljenem vezju in načrtovanju natančnosti izhodne napajalne napetosti 5, 10, 36 V in referenčne napetosti 5 V. Konec četrtega poglavja je namenjen stabilizaciji vezja. Za pretvorbo analognih signalov v digitalne so za visoko natančnost potrebni dobri AD in DA pretvorniki, ki jih v petem poglavju opišem in predstavim v samem vezju. Za nemoteno delovanje in varovanje kontrolnega vezja pred morebitnimi električnimi poškodbami je potrebna implementacija izolacije kontrolnega in krmilnega dela vezja. Razložena je tudi serijska digitalna komunikacija I2C, katero med seboj uporabljajo digitalne naprave, ki so uporabljene v vezju. Predzadnje poglavje obravnava tudi izolacijo med kontrolnim vezjem in USB priklopom, ki je namenjena programiranju mikrokontrolerja in razhroščevanju (angl. Debugging), to pa omogoča nastavljanje in nadgrajevanje programske opreme naprave brez poseganja v njeno notranjost. Izolacija je tukaj izvedena z opto-izolatorji. Ohišje in uporabniški vmesnik pa sta obravnavana v zadnjem poglavju, v katerem opišem načine realizacij, zasnovo za izgled ohišja ter osnovno zgradbo uporabniškega vmesnika.

Language:Slovenian
Keywords:digitalni laboratorijski usmernik, digitalno krmiljenje napetosti, krmiljenje toka z mikrokontrolerjem, električna izolacija vezji
Work type:Undergraduate thesis
Organization:FE - Faculty of Electrical Engineering
Year:2016
PID:20.500.12556/RUL-83504 This link opens in a new window
Publication date in RUL:16.06.2016
Views:2106
Downloads:689
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Secondary language

Language:English
Title:Design of a 300 W digital laboratory DC power supply
Abstract:
This dissertation of Digital Laboratory Power Supply discusses design, of a precision variable digital power supply, which can output control voltage from 0-30 V and current in a range of 0-5 A in 10 mA/mV increments. At the beginning I analyze problems in electrical schematics and PCB design and briefly explain how to use programs for electrical and PCB design. The main part consists of electrical design and implementation of this design onto the PCB, it also describes connection of a microcontroller with analog part and user interface of power supply. Analog section is divided into three chapters. The first chapter describes how to realize analog part of a power supply and its pre-regulation. Here the working principles of switching regulators and necessary calculations to get the device in proper working condition are discussed. Pre-regulation with switching regulator is primary used for achieving the most desired effect, the efficiency. This kind of regulators are designed for this purpose, especially when compared to the standard linear regulators. In this chapter the design of a switching regulator is analyzed in details. In particular the design of a switching regulator as an output follower. The forth chapter describes methods of analog control and implementation of operational amplifiers. The element that is usually not so often implemented in such design is a Hall sensor, which is used for current control and reading. For stable operation there is one more element needed, that is power supply for active devices in the circuit. All the power sources, that produce a voltages of 5,10,36 V and one reference voltage of 5 V are described. In the end of the chapter I’m discussing how to stabilize control circuit which is controlling analog section of power supply. For digital conversion of signals from analog to digital and digital to analog, high precision devices are needed. Their implementation and operation in a circuit is described in the fifth chapter. Protection against electrical shock hazard for the components and ground loops in the circuit is also analyzed. An electrical isolation between digital devices in circuit with a Radio Frequency isolator is introduced. I’m also describing serial I2C communication between a microcontroller and other devices in circuit. Sixth chapter describes isolation with optical separation of a USB port from internal microcontroller, which is needed for communication with computer, and can be used for debugging. This allows us to connect and program the device without internal manipulation. Electrical separation is made with Optocouplers. The enclosure for the device and user interface is introduced in final chapter. The design of the final structure and outer look of the device are described.

Keywords:digital laboratory power supply, precision variable power supply, voltage and current control with microcontroller, electrical isolation of circuits, switching regulator as voltage follower

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