Friday, 27 February 2026

 

Page 27 – Boost Converter Detailed Derivation (CCM)

Subject: Power Electronics
Converter Type: Step-Up Chopper
Mode: Continuous Conductio

Picture used in power electronics

n Mode (CCM)

                                            


1️⃣ Objective of Boost Converter

A Boost Converter increases DC voltage.

✔ Output Voltage > Input Voltage
✔ Used in SMPS, Solar Systems, EVs


2️⃣ ON State Analysis (Switch ON)

Time Interval: 0 → DT

  • Switch ON
  • Diode Reverse Biased
  • Inductor stores energy

VL = Vs

Using:

V = L (di/dt)

So:

di/dt = Vs / L

Inductor current increases linearly.

3️⃣ OFF State Analysis (Switch OFF)

Time Interval: DT → T

  • Switch OFF
  • Diode Conducts
  • Inductor releases stored energy

VL = Vs − Vo

Since Vo > Vs, inductor voltage is negative.

di/dt = (Vs − Vo) / L

Current decreases linearly.

4️⃣ Volt-Second Balance Derivation

Steady state condition:

Average inductor voltage over one cycle = 0

So,

VsDT + (Vs − Vo)(1 − D)T = 0

Simplifying:

Vo = Vs / (1 − D)


5️⃣ Ripple Current

During ON time:

ΔI = Vs D T / L

Ripple depends on:
  • Switching frequency
  • Inductance
  • Duty cycle

6️⃣ Important GATE Observations

  • As D → 1, output voltage increases sharply
  • Efficiency reduces for very high duty cycle
  • Inductor stores energy during ON time
  • Used in renewable & DC bus applications

 Final Formula Summary

✔ Vo = Vs / (1 − D)
✔ ΔI = Vs D T / L


Prepared for GATE & PSU – Shaktimatha Learning

No comments:

Post a Comment

  Operational Amplifiers – Complete Theory Page 15 – Active Low Pass Filter An Active Low Pass Filter allows low-frequency sig...