Page 49 – Multilevel Inverter (MLI) – Introduction
Subject: Power Electronics
Level: GATE / PSU / Interview
🔹 1. What is a Multilevel Inverter?
A multilevel inverter produces output voltage with multiple discrete levels instead of only two levels (+Vdc and −Vdc).
Instead of square waveform → staircase waveform → closer to sine wave.
🔹 2. Why Multilevel Inverters?
- Lower harmonic distortion (THD)
- Reduced switching losses
- Lower dv/dt stress
- Better output waveform quality
- Suitable for high voltage applications
🔹 3. Types of Multilevel Inverters
1️⃣ Diode Clamped (Neutral Point Clamped - NPC)
Uses clamping diodes to achieve multiple voltage levels.
2️⃣ Flying Capacitor (Capacitor Clamped)
Uses capacitors to generate intermediate voltage levels.
3️⃣ Cascaded H-Bridge (CHB)
Uses multiple H-bridge cells with isolated DC sources.
🔹 4. Number of Output Levels
For Cascaded H-Bridge: Number of levels = 2n + 1 Where n = number of H-bridge cells
Example: n = 2 → Levels = 5 n = 3 → Levels = 7
🔹 5. Advantages
- Low THD
- Reduced filter requirement
- Suitable for HVDC & FACTS
- High power applications
🔹 6. Disadvantages
- More components
- Complex control
- Voltage balancing issues
Exam Important Formula
CHB Levels = 2n + 1 NPC Diodes = (m − 1)(m − 2) Switch count increases with level
Multilevel Inverter Series – Shaktimatha Learning
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