The document discusses multilevel inverters, which convert direct current (DC) to alternating current (AC) and are utilized in high power and medium voltage applications. It highlights advantages such as reduced harmonic distortion, smaller common-mode voltage, and high efficiency at lower switching frequencies. Various types of multilevel inverters, including diode clamped, flying capacitors, and cascaded H-bridge types, are outlined alongside their applications in motor drives and renewable energy systems.

1. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
PRESENTATION BY :
I.VARUN KUMAR
M.R.DURGA PRASAD
3rd EEE,GMRIT,RAJAM

2. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
Inverter:
• The Inverter is an electrical device which converts direct current
(DC) to alternate current (AC).
Multilevel Inverter:
• The multi-level inverter is to synthesize a near sinusoidal
voltage from several levels of dc voltages
• The Multi level inverter is like an inverter and it is used for
industrial applications as alternative in high power and medium
voltage situations.
• It has been introduced in 1975 as alternative in high power and
medium voltage situations by NABLE ELAL

3. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
 The need of multilevel converter is to give a high output power
from medium voltage source.
Multilevel inverters have become more
popular over the years in electric high power applications with
less disturbances in voltage and the possibility to function at
lower switching frequencies than ordinary two level inverter.

4. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
1. Reduced harmonic distortion: Multilevel converters not
only can generate the output voltages with very low distortion,
but also can reduce the dv/dt stresses; therefore electromagnetic
compatibility (EMC) problems can be reduced.
2. Common-mode (CM) voltage: Multilevel converters produce
smaller CM voltage; therefore, the stress in the bearings of a
motor connected to a multilevel motor drive can be reduced.
ADVANTAGES:

5. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
3. Input current: Multilevel converters can draw input current with
low distortion.
4. Switching frequency: Multilevel converters can operate at both
fundamental switching frequency and high switching frequency
PWM. It should be noted that lower switching frequency usually
means lower switching loss and higher efficiency

6. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
The two level inverter is the simplest
type of three-phase voltage source
inverter and can be thought of as a
six pulse bridge in which the
thyristors have been replaced by
IGBTs with inverse-parallel diodes,
and the DC smoothing reactors have
been replaced by DC smoothing
capacitors
TWO LEVEL INVERTER

7. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
TYPES OF MODULAR MULTILEVEL INVERTERS
Multilevel inverters are three types.
1. Diode clamped or Neutral-Point Clamped type
2. Flying capacitors type
3. Cascaded or H-bridge type

8. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
DIODE CLAMPED MULTILEVEL INVERTER
• This inverter uses diodes and
provides the multiple voltage levels
through the different phases to the
capacitor banks which are in series.
• A diode transfers a limited amount of
voltage, thereby reducing the stress
on other electrical devices. The
maximum output voltage is half of
the input DC voltage.

9. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
FLYING CAPACITORS MULTILEVEL INVERTER
• The main concept of this inverter is
to use capacitors. It is of series
connection of capacitor clamped
switching cells.
• In this inverter switching states are
like in the diode clamped inverter.
• Clamping diodes are not required in
this type of multilevel inverters.

10. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam

11. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
 Multilevel cascade inverters are used to eliminate the bulky
transformer required in case of conventional multi phase
inverters, clamping diodes required in case of diode clamped
inverters and flying capacitors required in case of flying
capacitor inverters. But these require large number of isolated
voltages to supply the each cell.
 The combination of capacitors and switches pair is called an H-
bridge and gives the separate input DC voltage for each H-
bridge.
CASCADED H- BRIDGE MULTILEVEL INVERTER

12. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam

13. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
APPLICATIONS OF MULTILEVEL INVERTER
 High-voltage and Medium-voltage motor drives
 High voltage dc transmission
 Flexible AC transmission system (FACTS)
 Traction
 Active filtering
 Utility interface for renewable energy systems

14. DepartmentofMechanicalEngineering Humility Entrepreneurship Teamwork
Learning Social Responsibility Respect for IndividualDeliver The Promise
GMRInstituteofTechnology,Rajam
THANK YOU…