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EE 241 Design Problem

EE 241 Design Problem. Paguio , Cindy Sandoval, Andrew Valdez, Rozelle. Specifications. Typical Lab Supply Single Output Flyback converter in DCM Vi = universal supply (85V to 264V) Io = 0 to 3A Vo = 2V to 20V. Block Diagram. Linear Regulator. Flyback Converter. Assumptions:

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EE 241 Design Problem

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  1. EE 241 Design Problem Paguio, Cindy Sandoval, Andrew Valdez, Rozelle

  2. Specifications • Typical Lab Supply • Single Output • Flyback converter in DCM • Vi = universal supply (85V to 264V) • Io = 0 to 3A • Vo = 2V to 20V

  3. Block Diagram

  4. Linear Regulator

  5. Flyback Converter • Assumptions: • Efficiency = 80% • fs = 175kHz • Iout = 5A • Design Approach • 5 Outputs (4.3V, 8.3V, 12.3V, 16.3V, 20.3V) • Tap Configuration • 15V Primary Auxiliary Output • To power PWM Controller • 24V Secondary Auxiliary Output • To power op-amps in linear regulator and the flyback switcher

  6. Flyback Transformer Design • Primary Side: • Core: E14-3C90 • Ie = 78.6mm, Ae = 97.1mm^2, Ue =67 (1) N = 26.68 turns • Secondary Side: (2) 15V flyback auxiliary output: Nsec = 3.48 turns 24V flyback auxiliary output: Nsec = 4.93 turns

  7. Flyback Transformer • Secondary Side: • Multi-output tap configuration • Outputs are in 4V increments (4.3V, 8.3V, 12.3V, 16.3V, 20.3V) • Eq. 2 is used to get Nsec for Vout = 4.3V • Nsec(4.3V) = 0.998 turns • Nsec(4V) = 0.938 turns • Nsec(8.3V) = Nsec(4.3V) + Nsec(4V) • Nsec(12.3V) = Nsec(4.3V) + 2*Nsec(4V) • Nsec(16.3V) = Nsec(4.3V) + 3*Nsec(4V) • Nsec(20.3V) = Nsec(4.3V) + 4*Nsec(4V)

  8. Flyback Transformer • PWM Controller Circuit and Switch: • Osc pin: • fs = 175kHz, 1.8/RC, R >= 5kHz • R1 = 5kohms, C4 = 2nF • Sense pin: • Pout = Vout,max*Iout,max = 20.3*5A=101.5W • I_peak = (5.5*Pout)/Vin,min = (5.5*101.5)/(85*sqrt(2)) = 4.64A • Rsense = 1.0/I_peak = 1.0/4.64 = 215mΩ

  9. Flyback Transformer

  10. Flyback (PWM Controller)

  11. Flyback (Simulation) • Conditions: Vin = 85Vrms

  12. Flyback (Simulation) • Conditions: Vin = 85Vrms

  13. Switching Circuit

  14. Switching Circuit

  15. Switching Circuit

  16. Switching Circuit

  17. Switching Circuit

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