Ee 241 design problem
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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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Ee 241 design problem

EE 241 Design Problem

Paguio, Cindy

Sandoval, Andrew

Valdez, Rozelle


Specifications

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

Block Diagram


Linear regulator

Linear Regulator


Flyback converter

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


Flyback transformer design

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


Flyback transformer

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)


Flyback transformer1

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


Flyback transformer2

Flyback Transformer


Flyback pwm controller

Flyback (PWM Controller)


Flyback simulation

Flyback (Simulation)

  • Conditions: Vin = 85Vrms


Flyback simulation1

Flyback (Simulation)

  • Conditions: Vin = 85Vrms


Switching circuit

Switching Circuit


Switching circuit1

Switching Circuit


Switching circuit2

Switching Circuit


Switching circuit3

Switching Circuit


Switching circuit4

Switching Circuit


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