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Multiple Output, Portable Power Supply

Multiple Output, Portable Power Supply. ECE 345 Team #25 James Cairns Dinh Tuyen Thanh Lam Ashwin Pandav. Introduction.

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Multiple Output, Portable Power Supply

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  1. Multiple Output, Portable Power Supply ECE 345 Team #25 James Cairns Dinh Tuyen Thanh Lam Ashwin Pandav

  2. Introduction We chose this project due to our interest in the area of power electronics. This project would allow students in the laboratory environment to have access to a lightweight and versatile source of power. We are excited about this project because we will learn to interface components that we have studied in the past to design a useful tool.

  3. Our Goals • Create light-weight power supply • Allow for multiple output for use in the lab • Take advantage of power electronics to increase efficiency and decrease size

  4. Overview of Design • AC/DC converter (Rectifier) • Fly-back Converter (step down voltages) • Buck converters ( regulated output voltages)

  5. Design Flowchart AC Input 100-240 V Rectifier AC/DC Flyback Converter Output +/- 12 Adjustable (+/-10-16) BuckConverters Output +/- 5 Adjustable (+/- 3-6) Feedback Control

  6. Rectifier AC/DC

  7. Rectifier Without Capacitor

  8. Rectifier Calculations • C = Iout / 2 * f * Vout f=60Hz • Iout = Pmax /Vout = 155W/100√2 = 1.1A • C = 325μF • Choose Full-Wave Bridge capable of blocking maximum voltage = 340V

  9. Rectifier with Capacitor~ 100Volts AC

  10. Rectifier with Capacitor ~ 209 V AC

  11. Flyback Converter

  12. Flyback Converter (Basic Calculations ) • Np = number of turn on primary side • Ns = number of turn on secondary side • Vp = Voltage on the primary side • Vs = Voltage on the secondary side • Vox = out put voltage, where x = 1,.., 4 • D = duty cycle • Fi = flux • Vp = Np (dFi /dt) • Vs = Ns (dFi /dt) • Since (Vp & Vs ≠ 0) and (dFi /dt ≠ 0) => Vp / Vs = Np/Ns • When Switch on Vp = Vi • Switch off Vs = -Vox • D * Vp + (1-D)*(Vs*Np/Ns) = 0 • => D*Vi – (1-D) * Vox (Np/Ns) = 0 • => Vox = (Ns/Np) * (D / (1-D)) * Vi

  13. Flyback Converter (Gate Drive Duty Cycle & Transformer Turn Ratio) Derivation from previous slide • D = (Vox Np ) / ( Ns *Vi + Vox Np) • D= 1/ ( Vi / (Vox N)) +1 ) Where N = Np/Ns So, once D is chosen => N is found.

  14. Transformer Design --Transformer Saturation is a main concern -- To avoid this problem, we need to have N > Vdc* Δt / Bsat / Acore where Vdc = low end input voltage (140 V) Δt = D * 1/ fswitch D = duty cycle (on time) fswitch = switching frequency Bsat = saturation flux density Acore = Area of the core -- Choosing the proper size wire for coils on the transformer

  15. Transformer Design (continue) Inductor on the primary side Lpr =(D*Vin_min)^2/(2* fswitch* Pin) = (0.44 * 140)^2/(2* 50KHz* 155) = 255 uH

  16. Feedback Control

  17. Feedback Control ( Continued)

  18. Feedback Control (continue)

  19. Driver at High Voltage

  20. High Voltage Interface • MAX5003 – Peak Source Current = 570mA • Resistor between driver output and gate to reduce oscillations • Reduced Voltage Ratio 340/140V ≈ 22/9V • Ratio allowed for Vout = 1 & 2V vs. 10 & 20V

  21. Regulated Secondary Output • Vin = 9V VoH = 2V VoL = 1V D = 23%

  22. Regulated Secondary Output • Vin = 22V VoH=2V VoL = 1V D= 18%

  23. Buck Converter

  24. Buck Converter Calculations • VL = L di/dt = L Δi/Δt • ΔV = (1/8)(1-D)*Vo/(f2LC)  LC = (1-D)Vo/(8*f2*ΔV) • LC = 500E-12 @ ΔV = 0.2V • Diode on: Vo = L di/dt = L Δi/Δt L = Vo Δt/Δi • L = 185μH C = 2.7μF

  25. Buck Converter Output • Desired Ripple Voltage = +/-2%

  26. Buck Converter Efficiency • η = Pout / Pin = 91%

  27. Circuit Protection • MAX5003 Features - Under Voltage Lockout - Current Limiting • Buck Converter Features - Current Limited Internally - Under Voltage Protection

  28. Summary • Achieved desired rectifier output (low ripple voltage) • Reliable drive signal at high voltage • PWM achieved regulated output • Smooth/Adjustable output at Buck Converters

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