Analysis and Design of Multioutput Flyback …

1 Analysis and Design of MultioutputFlyback ConverterA study For A Lab Upgrade on the Flyback converter assignment atChalmers ElteknikMaster s thesis in Electric Power EngineeringAbdi AhmedAbdullahi KosarDepartment of Energy & EnvironmentChalmers University of TechnologyGothenburg, Sweden 2016 Master s thesis 2016:ENMA nalysis and Design of Multioutput FlybackConverterA study For A Lab Upgrade on the Flyback converter assignmentat Chalmers ElteknikABDI AHMEDABDULLAHI KOSARD epartment of Energy & EnvironmentDivision of Electric Power EngineeringChalmers University of TechnologyGothenburg, Sweden 2016 Analysis and Design of Multioutput Flyback ConverterMaster s thesis 2016:ENMABDI AHMEDABDULLAHI KOSARc ABDI AHMEDABDULLAHI KOSAR, of Energy & EnvironmentDivision of Electric Power EngineeringChalmers University of TechnologySE 412 96 GothenburgSwedenTelephone +46 (0)31 772 1000 Cover:Multi-output Flyback converter prototype PCBC halmers ReproserviceGothenburg 2016 Analysis and Design of Multioutput Flyback ConverterMaster s thesis 2016:ENMABDI AHMEDABDULLAHI KOSARD epartment of Energy & EnvironmentDivision of Electric Power EngineeringChalmers University of TechnologyAbstractThis thesis work is done in order to improve the existing lab in Chalmers forthe study of Power Electronics.

2 Assignments for the practical lab and computersimulation sessions of a Flyback converter have been reviewed and analysed. Theanalyses of the existing assignments shows that the circuit board used in the labtoday is a multi purpose circuit and it is difficult to relate a equivalent circuitdiagram of a Flyback converter . Furthermore, there is no relationship between thecircuit and the simulation simulation was done using PSpice and a prototype PCB board built with the aimof showing some of these interesting concepts in the course. The main suggestionsare related to the simplification of the circuits so that immediate correlation can bemade between the circuits being shown in the class and the PCB used in the simulation model can be used in the simulation session of the new simulation model and the circuit board can demonstrate the role of theinductor in the Flyback transformer by varying its value. Another area of improve-ment would be on demonstrating of magnetics theory.

3 There is no simulation orpractical assignments about magnetics in the course today. Understanding the re-lation between the current ripple and magnetic flux is in the scope of the is also important to understand how high frequency affects the losses and thesize of the core. Two transformers are designed in order to investigate these rela-tionships. The result of the transformer Design shows that a new assignment thatcan demonstrate how magnetic core behaves can be : Flyback , Multi-output, DCM,CCM, LM5020,Switch modepower supplyvAcknowledgementFirst of all we would like to thank the Almighty for making this possible. Thecontributions we had from our supervisor Andreas Henriksson were numerous andimmesuarable and we would like to acknowledge his commitment and effort inenabling this work. Of notable mention is Altran, Ericsson and Chalmers whowere the collaborating and support from our family members and friends will not gounappreciated.

4 Thank , Abdullahi would like to acknowledge the Swedish Institute for the generousscholarship for his master s & AbdullahiGothenburg, September 27, 2016 ContentsAbstractvAcknowledgmentsviiConte ntsixList of FiguresxiList of TablesxivAbbreviationsxv1 Background .. Problem .. Purpose .. Scope ..32 Pedagogic Existing Flyback Lab for ENM060 .. Existing Simulation Task for Flyback in ENM060 .. Suggestions ..83 Technical Circuit Description .. Operating Modes .. mode of operation .. mode of operation .. between CCM and DCM .. Magnetics .. of a magnetic core .. of Air gap .. Control circuit of the Flyback .. 244 Design and simulation of the System specifications .. Determination of Maximum duty ratio (Dmax) .. Transformers primary inductance (Lm) .. Core selection .. the maximum flux swing ( Bmax).

5 Windows area product AP .. the required number of minimum primary turnsNminp.. Determing the Secondary Turns .. Determing the Wire Diameter .. Choosing the diodes .. Determine the output capacitors .. Design of Clamp and Damping circuit .. Compensator Design .. 445 Simulation and PCB Design of a Existing Simulation Model.. Proposed Simulation Model .. PCB Design .. Measuring .. 516 Simulations and Simulations .. value in CCM .. value in DCM .. sense simulations .. Network .. Measurements .. 577 Results598 Discussion639 Conclusion and Future .. Future Work .. 66xCONTENTSB ibliography68A Derivations of the mathematical converter .. Control .. Filter .. Matlab code for compensation network .. A2B Data N87 datasheet .. A1xiCONTENTSxiiList of Circuit diagram of the Flyback converter .

6 Equivalent Circuit of Flyback converter .(a) When the switch is onand the diode is blocking.(b) When the diode is forward biased andthe switch is off.. Voltage and current wave forms of Flyback converter working on CCM Current and Voltage wave forms of the Flyback converter working inDCM.. Voltage and current wave forms of a Flyback converter working onBCM .. Normalized output currentIoat the boundary as a function of dutycycle (D) for a Flyback converter .. Relationships between the electrical and magnetic quantities .. B-H loop .. Hysteresis in the B-H plane for ferromagnetic cores. Dashed line;with air-gap Solid line;with no air-gap .. Type II error amplifier .. flow chart of Design procedure[1] .. Switch and diode utilization factor versus duty cycle of a Flyback .. Relative core losses versus frequency for N87 core material .. Primary inductor mode current, blue for DCM and red for CCM.

7 Hysteresis in the B-H plane for ferromagnetic cores.(a) typical fly-back operating in CCM.(b) typical Flyback operating in DCM .. An ideal diagram of the transformer .. (a)Output capacitor current.(b) Simple circuit diagram of the out-put capacitor, diode and load .. Circuit showing the arrangement of a TVS and diode to achieveclamping.. 43xiiiLIST OF Voltage across the MOSFET: (a) Without clamp (b) With clamp(c) with clamp and damping resistance and capacitor .. Equivalent circuit of a Flyback converter .(a) ON mode (b) OFFmode.. Theoretical bode plot of the system .. The existing simulation model.. Simulation model of a Flyback converter with two outputs .. Top Silkscreen.. Top copper trace .. Bottom Copper .. Simulation: Current waveforms in a Flyback converter operating inCCM mode with different input voltages: (a)Vd=15 (b)Vd=30.

8 Current waveforms in a Flyback converter operating in DCM modewith different input voltages: (a)Vd=30 (b)Vd=15.. Simulation: Current waveforms in a Flyback converter operating inDCM mode with different input voltages: (a)Vd=15 (b)Vd=30.. Current measurement in the simulation model .. Transient responte of the output voltage: (a) When load-step isapplied at input 1 (b) When load-step applied at input 2 .. Measured result .. Drain Voltage with lower inductance value .. Overview of the circuit board compered to the circuit diagram ofthe Flyback converter .. Overview of two transformer with two different frequencies. Thefrequency of the large and small transformers are 65 and 300 kHzrespectively .. 61xivList of System specification .. The RMS value of the current and the resulting primary inductance Core list and Design properties.

9 Number of turns and core type .. Copper diameter and their current carrying capacity for differentA/cm2.. Rms value of the current and the required number of wires .. Ratings of the power stage components .. 42xvLIST OF BackgroundPower electronic converters is a common object in today s electronic world andfor a very good reason. With quite a bit of interest in smaller sized consumerproducts and energy efficiency, there is a need for power supplies to adaptto these needs. The evolution of power supplies, as does many other electronicitems, follows a trend that ends up with better and more efficient need to control power more efficiently and reduce losses coupled with theimprovement and advancement of power electronic switches led to the adoption ofswitched mode power supplies (SMPS). The main principle being that the inputis connected to the energy storage devices (capacitors and inductors) only as longas it is required; not all the time as is with the case of linear regulators.

10 Powerelectronic switches that can be switched as fast as several MHz enables switch mode power supply has a high efficiency which reaches up to 90 %. Thehigh efficiency eliminates the need for big heat sinks and therefore the size and costof the power supply decreases significantly. For this reason, a SMPS is preferredto use in situations where a high supply efficiency is necessary [2]. Some of theareas where this technology is applicable is in battery-powered and hand-heldapplications where the battery lifetime and the temperature are essential [3]. Thedisadvantages of an SMPS are minor and can be overcome with a proper , switched mode power supply Design is inherently a time consuming jobrequiring many trade-offs and a large number of Design electronics is one of the four major areas taught to electrical power engineer-ing students at Chalmers University of Technology. The main reason being that PROBLEMC hapter 1is an area that has wide applications and require some level of familiarity to futureelectrical engineers.