Switch Mode Power Supply Presentation

Design and Implementation of Switch Mode Power Supply

Two stage isolated switch mode power supply Group Members:Alamzeb Khan Jadoon FA11-BEE-003Adnan Durrani FA11-BEE-002Sheraz Amin FA11-BEE-008

Supervisor Name: Dr. Abdul RasheedCo-Supervisor Name:Saima Habib GoalDesigning of 500 watt DC power supply.An efficient design, smaller size and less weight .

Block Diagram:Rectifi-cation and Filterat-ion Boost conver-terFull bridge topology Control CircuitryFeedbackDC OutputAC InputHigh frequency transfo-rmerWhat is SMPSSMPS stands for switch mode power supply.SMPS uses aswitching circuitryto convert electric power efficiently.Efficiency of SMPS is about 80%.Compact

Difference between Linear and Switch Mode Power Supply

Boost converter The boost converter is working on the continuous conduction mode.Continuous conduction mode of a boost converter assumes two states for each switching cycle.

Working PrincipleIn the On-state, the switch S is closed, resulting in an increase in the inductor current.When the switch is opened, current will be reduced as the impedance is higher.

Topology UsedThe topology we are using to design SMPS is Full-bridge converter.Full bridge converter has more than 80% efficiency upto 1000 watts of power.This topology isolates the input from the output through a transformer.We will be using ferrite core transformer because it operates on high frequency.

Full bridge diagram:

Principle of workingThe capacitor at the input gets charge , resulting in operation of Q1 and Q4.In the discharge of the capacitor or in the next half cycle Q2 and Q3 will be in on state.This results in producing a high frequency square wave AC. The output is fed to an isolation transformer.

SimulationResults:Load Resistance=33OhmsPin=23.1 WPout=12.27 W

Current at OutputCurrent at InputContinued:Inductive Load connected to Output (14A, 24V DC Motor)Power TransformerWe are using a high frequency switching power transformer.We will be operating on 1.5 MHz frequencyRectification and FilterationWe are using a Diode bridge rectifier for rectification.Rectifiers are Power diodes (5406)For, filteration we have used a capacitor.

Pulse Width ModulationPulse-width modulation(PWM), orpulse-duration modulation(PDM), is amodulationtechnique that controls the width of the pulse based on modulator signal information.We are using the PWM chip for the generation of switching frequency.

FeedBackWe have used a Opto-Coupler in the feedback circuitry.Opto-Coupler is use for protection purposes.It provides isolation between the primary and secondary sides.

Equations Used:For boost converter:

For Full Bridge (inverter):

Equations USED: 19Componenets usedMOSFET (IRF740)Power Diodes (5406)Inductor (200uH)Inductor (130uH,35A)Capacitors (10u, 0.1u,1n,104p)Opto-Coupler (4N25)High Frequency TransformerPWM Chip (UC 3825)CT (25A,12V)

Applications:LCD monitor/ TV.Portable charger.LED lighting.Home Appliances.PC power supply.Note book adapter.Set top box.Laptop chargers.

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