slides topic

Five-Level NPC/H-Bridge Inverter System with dual 18-pulse rectifier
LEDAR, Ryerson University
Topic 8
Other Multilevel Voltage Source Converters

Lecture Topics
NPC/H-Bridge Inverters
Flying-Capacitor Inverters
Other Multilevel
Voltage Source Converters

Compared with three-level NPC Topology:
Voltage levels increases from three to five Inverter output voltage and power are doubled
Device count is doubled
Five-Level Topology
NPC/H-Bridge Inverters

IPD Modulation
NPC/H-Bridge Inverters

Waveforms and FFT (Five Level)
Inverter Phase Voltage
Line-to-line Voltage
NPC/H-Bridge Inverters

Waveforms and FFT (Five Level)
Frequency modulation index: mf = 18
NPC/H-Bridge Inverters

Five Level Topology
Complementary
Switch pairs:
S1 and S’1;
S2 and S’2; S3 and S’3;
S4 and S’4;
Multilevel Flying Capacitor Inverters

Switching State (five-level)
Multilevel Flying Capacitor Inverters

fsw (device) = 60(mf ) = 720Hz
fsw (inverter) = 60(4mf ) = 2880Hz
Phase-Shifted PWM
Multilevel Flying Capacitor Inverters

Features
- Low harmonic distortion with low dv/dt
- Modular design
Drawbacks
- Large number of dc capacitors
- Complex pre-charging circuits
- Difficulties in dc cap voltage balancing control
Summary
Multilevel Flying Capacitor Inverters