Switched Mode Power Supply Engineering Essay

Switched rule creator Supply Engineering EssayABSTRACTSwitched expressive style world spot Supply (SMPS) is the most prevailing architecture for DC power lend in modern systems, primarily for its capability to handle variable piles. aside from efficiency the size and free weight of the power supplies is becoming a great area of concern for the Power Supply Designers. In this thesis an AC to DC converter SMPS tour, having a power MOSFET for reverse operation and a PWM ground Feedback forget me drug for driving the electric switch of the MOSFET, is designed and simulated in NI MULTISIM round design environment. Further the same circuit is Hardware implemented and experimented using NI ELVIS Suite.In this design the line potency at 220V/50Hz is taken as input, this potential drop is stepped down, rectified and passed through filter optical condenser to forget an unregulated DC voltage. This unregulated voltage is chopped using a MOSFET switch, driven by PWM feedback ratify, to control the make voltage level. An Isolation Trans micturateer is used to isolate the DC widening from input supply. The transformer widening is again rectified by the broad(prenominal) oftenness Diode bridge rectifier and is filtered using a capacitor to give the regulated DC output. A potential regulator is connected to give the precise voltage output.The feedback network generates a high relative frequency PWM signal to drive the MOSFET switch. The dc voltage at the output depends on the width of the switching pulse. The pulse width is varied with the changes in the DC output voltage level, this change in the pulse width cancels the output voltage change and the SMPS output remains constant irrespective of load variations.CHAPTER 1INTRODUCTION1. INTRODUCTIONPower Electronics is the art of converting electrical energy from one form to another in an efficient, clean, compact, and robust manner for convenient utilisation. The never ending drive towards smaller and l ighter product poses serious challenges for power supply designers.The aim of the project is to design, test and implement a switched mode power supply (SMPS) circuit for AC to DC conversion, having a power MOSFET for switching operation and a PWM based feedback circuit to drive the MOSFET switch using NI MULTISIM circuit design environment and NI ELVIS Breadboard. understand1.1 BLOCK DIAGRAM SMPSCHAPTER 2THEORITICAL BACKGROUND2. THERORITICAL BACKGROUNDPower SuppliesA power supply is a component, subsystem, or system that converts electrical power from one form to another commonly from alternating current (AC) value power to direct current (DC) power. The proper operation of electronic devices ranging from personal computers to military equipment and industrial machinery depends on the performance and reliability of DC power supplies.Power supplies are circuits that generate a fixed or controllable magnitude dc voltage from the available form of input voltage. Integrated-circuit ( IC) chips used in the electronic circuits need standard dc voltage of fixed magnitude. Many of these circuits need intumesce-regulated dc supply for their proper operation.Even a commodity switch-mode power supply must be able to survive sudden peaks that far exceed its average operating levels. Engineers calculating power supplies or the systems that use them need to check their supplies behaviour under conditions ranging from quiescent to worst-case.Todays power supplies are driving to a level of efficiency never seen before, requiring design engineers to perform numerous specialized power touchstones that are time-consuming and complex.The power supply is integral to virtually every type of line powered electronic product, and the switch-mode power supply (SMPS) has become the ascendant architecture in digital computing, networking, and communications systems. A single switch-mode power supplys performance or its failure can affect the fate of a large, expensive system.SMPS The prevailing DC power supply architecture in most modern systems is the Switch-Mode Power Supply (SMPS), which is known for its ability to handle changing loads efficiently. The power signal path of a typical SMPS includes passive, active, and magnetic components. The SMPS minimizes the use of lossy components much(prenominal) as resistors and additive-mode transistors, and emphasizes components that are (ideally) lossless switch-mode transistors, capacitors, and magnetic.Like a linear power supply, the switched mode power supply too converts the available unregulated ac or dc input voltage to a regulated dc output voltage. However in case of SMPS with input supply drawn from the ac mains, the input voltage is first rectified and filtered using a capacitor at the rectifier output. The unregulated dc voltage across the capacitor is then fed to a high frequency dc-to-dc converter. Most of the dc-to-dc converters used in SMPS circuits collect an intermediate high frequency ac con version stage to facilitate the use of a high frequency transformer for voltage scaling and isolation. The high frequency transformer used in a SMPS circuit is much smaller in size and weight compared to the low frequency transformer of the linear power supply circuit.The Switched Mode Power Supply owes its name to the dc-to-dc switching converter for conversion from unregulated dc input voltage to regulated dc output voltage. The switch engaged is turned ON and OFF (referred as switching) at a high frequency. During ON mode the switch is in saturation mode with negligible voltage drop across the aggregator and emitter terminals of the switch where as in OFF mode the switch is in cut-off mode with negligible current through the collector and emitter terminals. On the contrary the voltage-regulating switch, in a linear regulator circuit, always remains in the active region.Details of some popular SMPS circuits, with provisions for incorporating high frequency transformer for voltag e scaling and isolation, have been discussed in next few lessons. In this lesson a simplified schematic switching arrangement is described that omits the transformer action. In fact there are several other switched mode dc-to-dc converter circuits that do not use a high frequency transformer. In such SMPS circuits the unregulated input dc voltage is fed to a high frequency voltage chopping circuit such that when the chopping circuit (often called dc to dc chopper) is in ON state, the unregulated voltage is employ to the output circuit that includes the load and some filtering circuit. When the chopper is in OFF state, zero magnitude of voltage is applied to the output side. The ON and OFF durations are suitably controlled such that the average dc voltage applied to the output circuit equals the desired magnitude of output voltage. The ratio of ON time to cycle time (ON + OFF time) is known as duty ratio of the chopper circuit. A high switching frequency (of the order of 100 KHz) an d a fast control over the duty ratio results in application of the desired mean voltage along with sing voltage of a very high frequency to the output side, consisting of a low pass filter circuit followed by the load. The high frequency leaf in voltage is effectively filtered using small values of filter capacitors and inductors.SMPS technology tolerates on power semiconductor switching devices such as metallic element Oxide Semiconductor Field Effect junction transistors (MOSFET) and Insulated Gate Bipolar Transistors (IGBT). These devices offer fast switching times and are able to withstand erratic voltage spikes. evenly spell outant, they dissipate very little power in either the On or Off states, achieving high efficiency with low heat dissipation. For the most interrupt, the switching device determines the overall performance of an SMPS. Key measurements for switching devices include switching loss, average power loss, safe operating area, and more.Choice of TopologyThe re are several different topologies for the switched mode power supply circuits. Some popular ones areFly-backForwardPush-pullHalf bridgeFull-bridgeA particular topology whitethorn be more suitable than others on the basis of one or more performance criterions like cost, efficiency, overall weight and size, output power, output regulation, voltage ripple etc.All the topologies listed above are capable of providing isolated voltages by incorporating a high frequency transformer in the circuit.Applications of SMPSTo reduce cost, size and weight of a power supply.TVs, monitors, PCs, laptop and camcorder power packs, printers, fax machines, VCRs, portable CD players, microelectronics-based devices in automotive, computing, communications, consumer electronics, and industrial applications use SMPS.2.5 PWM ConceptsPWM or Pulse Width Modulation is the intonation technique where frequency and Amplitude of the pulse signal is not varied and the pulse width or the duty cycle is varied to enc ode the information. A common use of PWM is to control the average current or potency input to a device.In this project the PWM Signal is generated as feedback control signal for driving the switching of the MOSFET switch. The output Voltage is taken as the source level. A sine revolve is generated using LMH6622MA OPAMP and 555 Timer. This sine prosper signal is compared with the reference voltage using LM311 comparator, and the pulse width of the PWM is determined by this comparison. This switching period determines the voltage at the output. Thus if there is any change at the output Voltage, the corresponding change in the PWM pulse width will nullify its effect and the output voltage will be restored to desired value. skeleton2.1 PWM wave generationCHAPTER 3ELECRONICS DESIGN TOOLS3. ELECTRONICS DESIGN TOOL3.1 NI MULTISIMNI Multisimor formerlyMultiSIMis an electronicSchematic Captureand simulation program which is part of asuiteof circuit design programs, along withNI Ultiboar d. Multisim is one of the few circuit design programs to employ the originalBerkeleySPICEbased software simulation. MultiSIM was to begin with created by a company namedElectronics Workbench, which is now a subsidiaryofNational Instruments. Multisim includes a microcontroller simulation module called MultiMCU, as well as integrated import and exportation features to thePrinted Circuit Boardlayout software in the suite, Ultiboard.Multisim is the chief competitor toCadenceOrCAD, another electronic schematic design and simulation software.3.2 Features of MULTISIMYou dont need to be a SPICE expert to design with Multisim. With an intuitive capture environment and an easy-to-use interface to industry-standard SPICE simulation, Multisim software can help you immediately begin designing and validating your PCBs. You can prevent costly prototype iterations and lost development time, as well as ensure quality with simulation and measurements earlier in your design flow.The Multisim product f amily (Base,Full,Power Pro) provides a complete set of tools for professional PCB designersIntuitive design environmentModeless wiring and placementInteractive virtual measurement instruments to view simulation and real signalsCircuit wizards for automatically generating commonly used circuitryRubber banding on parts/movesFast-retrieval parts binEasy export toNI Ultiboardfor layoutComplex designs can be accomplished with advanced Multisim features from 24 sophisticated SPICE analyses to a comprehensive component library all the fleck taking advantage of an easy-to-use design environment. Designers can incorporate the latest parts using a custom component wizard. They can also use NI LabVIEW measurement software to advance real measurements into simulation for rapidly prototyping and testing designs.More than 16,000 components, all with models ready for immediate simulationDevice models from lead manufacturers such as Analog Devices and Texas InstrumentsEasy addition of new parts and simulation modelsComprehensive suite of analyses, including Monte Carlo and Worst Case3.3 NI MULTISIM 11Multisim and Ultiboard 11.0 introduce a number of new features and enhancements to make capturing designs, simulating behaviour, and defining board layout faster and easier. Feedback circuit of this project work was designed in NI MULTISIM 11 and rest of the circuit was imported from version 10 to 11 and then integrated in MULTISIM 11 for final simulation.3.4 NI ELVISThe National Instruments Educational testing ground Virtual Instrumentation Suite(NI ELVIS) is a LABVIEW based-design and prototyping environment for Universities science and engineering laboratories. The NI ELVIS featuring an integrated suite of 12 instruments in one compact form factor is ideal for hands-on learning (http//www.ni.com/nielvis/). NI ELVIS is a primary component of the NI electronics education platform along with NI Multisim, the leading tool for SPICE simulation and schematic capture, and NI Lab VIEW software. ( http//zone.ni.com/devzone/cda/tut/p/id/7159)3.5 Components of NI ELVISNI ELVIS includes 12 of the most commonly used testing ground instruments including an oscilloscope (scope), digital multimeter (DMM), function generator, variable power supply, dynamic signal analyzer (DSA), bode analyzer, 2- and 3-wire current-voltage analyzer, arbitrary wave form generator, digital reader/writer, and impedance analyzer in a single platform. This compact, yet powerful assortment of instruments translates into cost savings for the lab, both in terms of lab space as well as lower-maintenance costs.( http//zone.ni.com/devzone/cda/tut/p/id/7159)Figure 3.1Following Components were used for this project workFigure 3.2 The Function GeneratorFigure 3.3 Variable Power suppliesFigure 3.4 digital MultimeterFigure 3.5 OscilloscopeFigure 3.6 Complete Circuit Setup with NI ELVISCHAPTER 4COMPONENTS SELECTION4. COMPONENTS SELECTIONFor NI MULTISIM4.1 Power supplyAC powerFigure 4.1Voltage RMS = 230VVoltage offset= 0VFrequency (f)= 50HzTime Delay = 0ns4.2 Step-Down TransformerTransformer Rated available in multisim LibraryFigure 4.2 primary feather Voltage (max) = 350VPrimary online (max) = 5ASecondary Voltage (max) = 15VSecondary Current (max) = 1AOutput Power (max) = 5kVAPrimary to Secondary Turns Ratio = 20Leakage Inductance = 1mHPrimary Winding Resistance =1OhmSecondary Winding Resistance = 1Ohm4.3 Unregulated Rectifier1J4B42 Single Phase Bridge RectifierFigure 4.3Repetitive Peak abrogate Voltage (max) = 600V reasonable Output Rectified Current = 1 AJunction Temperature = -40 to 150 oCPeak Forward Voltage (max) = 1V4.4 MOSFET for change by reversal ApplicationBS170N-Channel Enhancement Switching TransistorLow On- resistance proud Switching SpeedLow CapacitancesUsed for Analog and/or Digital SwitchSwitch DriverConverters/ChoppersFigure 4.4VDS max. = 20VVGS max. = +15/-40 VID max. = 50 mARDS (typ) = 25ton = 1nstoff = 5ns4.5 graduate(prenominal) Frequency Isolation TransformerFigure 4.54.6 Rectifier with high Frequency DiodeIN4148, Fast Switching DiodesFigure 4.6Repetitive peak reverse voltage = 100VReverse Voltage = 70VForward Voltage (max) = 1VAverage Forward current = 150 mAReverse Current (max) = 50 mABreakdown Voltage (min) = 100VDiode Capacitance (max) = 4 pFRectification Efficiency (min) = 45%Reverse Recovery Time = 8ns4.7 Voltage RegulatorLM7805CT3 terminal-1A Positive Voltage regulatorFigure 4.7 Output Current up to 1A Output Voltage of 5V Thermal Overload Protection inadequate Circuit Protection Output Transistor Safe Operating Area ProtectionLine regulation = 4-100mVLoad regulation = 9-100 mVQuiescent Current = 5mADropout Voltage = 2VPeak current = 2.2 A4.8 555 TimerFigure 4.84.9 LMH6622MA OPAMPFigure 4.94.10 LM311N comparatorFigure 4.10CHAPTER 5TESTING CIRCUITS AND SIMILATION RESULTS5. TESTING CIRCUITS AND SIMULATION RESULTS5.1.1 Following Circuit was designed for AC-DC conversionFigure 5.15.1.2 Simulation Output of AC-DC conversi onFigure 5.25.2.1 Circuit for Analysis of MOSFET Switch performanceFigure 5.35.2.2 Simulation output for MOSFET Switch at 50kHzFigure 5.45.3.1 Circuit of Analysis of Voltage regulator combined with RectifierFigure 5.55.3.2 Simulation Output of Voltage Regulator performanceFigure 5.65.4.1 Open enlace Circuit Without Isolation TransformerFigure 5.75.4.2 Simulation Output of Open Loop CircuitFigure 5.85.5.1 Feedback CircuitFigure 5.95.5.2 Feedback Circuit Simulation OutputFigure 5.105.6.1 SMPS CircuitFigure 5.115.6.2 SMPS OutputFigure 5.12CHAPTER 6HARDWARE IMPLIMENTATION ON NI ELVIS6. HARDWARE IMPLEMENTATION ON NI ELVISThe SMPS circuit designed in NI MULTSIM was further implemented in hardware using NI ELVIS as the suitable platform for circuit instruction execution and testing.6.1 Component Used6.1.2 Diode 1N4007bridge Rectifier6.1.3 BS 170 MOSFETSwitch6.1.4 Radio TransformerIsolation Transformer6.1.5 Diode 1N4148High frequency rectifier6.1.6 555 TimerSquare wave Generation6.1.7 TL O6021 OPAMPSine wave Generation6.1.8 LM311 ComparatorPWM Switch driver signal6.1.9 LM 7805CTVoltage Regulator6.1.1 Step down Transformer1.6 AMP12 0 12 configuration Figure 6.1Figure 6.2 SMPS circuit on NI ELVIS6.2 Simulation OutputsOPEN LOOP6.2.1 Stepped Down AC Voltage from TransformerFigure 6.3 Stepped down AC input6.2.2 Rectified Unregulated DC voltage from (IN4007) Diode Bridge RectifierFigure 6.4 Rectified Unregulated DC6.2.3 Output waveform from the Filter capacitorFigure 6.5 Unregulated DC From filter Capacitor6.2.4 Chopped DC From the MOSFET switchFigure 6.6 Mosfet Chopped DC6.2.5 Output from High Frequency (40-50 KHz) Transformer taking in chopped DC .This Transformer also Isolates input from output.Figure 6.7 High Frequency Transformer Output6.2.6 Output from Bridge Rectifier designed from 1N4148 High frequency Diodes.An approximate DC signalFigure 6.8 High frequency Diode Rectifier Output6.2.7 Final Output of the SMPSAn stabilized voltage of 5 V maintained with aid of fee dback mechanism and the Voltage Regulator LM7805Figure 6.9 SMPS OutputFeedback Circuit6.2.8 555 Timer based Square wave generator circuit output44.4Khz Square wave SignalFigure 6.10 555 Timer Generated Square wave6.2.9 Sine wave generated from TLO6021 OpAmp based circuit taking as input the strong wave generated from 555 Timer based generator circuit.Figure 6.11 Sinewave generated from Opamp TLO60216.2.10 The sine wave generated above is compared with the final SMPS Output Anda PWM wave is generated to drive the MOSFET switch in a way that theoutput is regulated back to fixed desired value (5V) if it deviates.Figure 6.12 Feedback PWM SignalCHAPTER 7CONCLUSIONCONCLUSIONSuitable components were selected and tried for desired performance. Functional verification was performed on combined circuit of the selected components for open loop network both in NI MULTISIM and on NI ELVIS. PWM based feedback network was successfully designed tested and implemented both in NI MULTISIM and in Har dware using NI ELVIS Suite. The Design and implementation of desired SMPS circuit was successfully completed.