1.
THREE LEVEL
INVERTERS
By Anik Tarafder
EE(B),83

2.
NEED FOR MULTILEVEL INVERTER
High Power application
Staircase waveform
Input Current
Switching Frequency
Renewable Energy sources
Only disadvantage – More Switches, Cost

3.
BASIC CONCEPT
Use of Power Semiconductor
Switches in series - with several lower
Voltage dc sources - staircase voltage waveform
Lower voltage dc sources
– Capacitors, Batteries, PV cells

4.
TYPES
Diode Clamped Multilevel Inverter
Flying Capacitor Multilevel Inverter
Cascade Multilevel Inverter

5.
DIODE CLAMPED MULTILEVEL
INVERTER
Let, m → number of nodes or levels
Then, We require,
(m-1) → Capacitors
2(m-1) → Switching Devices
Example :-
m= 6
Therefore,
Capacitors – 5
Switching Devices - 10

6.
CIRCUIT DIAGRAM

7.
SWITCHING STATES

8.
OUTPUT VOLTAGE WAVEFORM OF
THREE LEVEL INVERTER

9.
FEATURES OF DIODE CLAMPED
INVERTER
High Voltage rating for blocking diodes
Unequal Switch device Rating
Capacitor Voltage Unbalance

10.
Advantage & Disadvantage
ADVANTAGES
➢Harmonic Content is
less-filters avoided
➢Efficiency – High
➢Control method - simple
DISADVANTAGES
➢Difficult to control the
real power of individual
converter
➢Need for more
clamping diodes

11.
Thank You