AC/DC to DC converter

If you don't know what is K1 L1 L2 1 transformer directive means, you should check ¹ for more details.

1. Forward converter

1.1. One-switch sigle-ended forward converter (isolated buck converter)

This is essentially a buck converter with transformer inserted.

We want to operate in Continuous Conduction Mode. $I_{Lout}$ never reach zero.

In DCM we may have peak detect phenomina, we $V_{out}^{'} = (3-4) \times V_{out}$

ESR is from $C_{OUT}$, and $\Delta I$ is effected by the design of $L_{out}$. Rule of thumb is $\Delta I$ = 10% to 40% of full load.

Refer ² for more details.

1.2. Two-switch sigle-ended forward converter (isolated buck converter)

also called asymmetrical half bridge forward

2. Flyback converter

Transfer function ³ is

where $n$ is turn ration, and $D$ is duty cycle.

2.1. RCD Clamp

• See more at RCD Clamp

3. Peak current control mode (Current-Programmed Control)

UCC28C42 from TI using this control method.

Refer to chapter 18 of ⁴, and ⁵.

4. Slope compensation

Refer to ⁶ for more information.

D<50% turburlance is faded out

If Duty cycle $D>50%$, $I_L$ with turburlance is not stable.

Using new $I_{Lref}$ to solve the problem.

How to generate the new $I_{Lref}$?

5. Practical consideration

5.1. How to use Impedance Analyzer

The table is adapted from ⁷.

Pending

• https://archive.nptel.ac.in/course.html
• NOC:Fundamental of Power Electronics (Video)
  • Week 12
    • Intro for close loop control
    • Close looping dc-dc converters
    • Simulation of close loop control
    • Current control for battery charger application
    • Instability in current control and slope compensation
    • Slope compensated current control
    • Simulation of current control
    • Single phase inverter with sinusoidal pwm
    • Simulation of sinusoidal PWM
• NOC:Control and Tuning Methods in Switched Mode Power Converters
  • Week 02
    • Lecture 12 : Interactive MATLAB Simulation and Case Studies

6. References

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