three level diode clamp inverter. that converts any type of DC ( rectified, PV cell, battery etc.) to AC supply. we made by mosfet and ardiuno . in this ppt we present the Simulink model of a three-level inverter and the hardware presentation of the inverter.

1. PROJECT PRESENTATION
ON
DIODE CLAMP THREE LEVEL INVERTER
UNDER THE
GUIDENCE OF;
Mr. Ashish Srivastava
PRESENTED BY;
Vinay singh

2. INTRODUCTION TO INVERTER
 A power inverter, or inverter, is an electronic device or circuitry that
changes direct current (DC) to alternating current (AC).
 The input voltage, output voltage and frequency, and
overall power handling depend on the design of the specific device or
circuitry. The inverter does not produce any power; the power is provided
by the DC source.

3. CONCEPT OF MULTI-LEVEL INVERTER
 Mostly a two-level inverter is used in order to generate the AC voltage from DC
voltage
 A two-level Inverter creates two different voltages for the load If Input Voltage is
Vdc. Then it produces output as +Vdc/2 AND –Vdc/2 based on switching of power
devices.
 This method of generating AC output seems to be Effective but posses following
drawbacks:
• High Harmonic Distortion in Output Voltage.
• High dv/dt.

4. CONCEPT OF MULTI-LEVEL INVERTER
In order to create a smoother stepped output waveform, more than two voltage levels
are combined together and the output waveform obtained in this case has lower dv/dt and
also lower harmonic distortions.
Smoothness of the waveform is proportional to the voltage levels, as we increase the
voltage level the waveform becomes smoother but the complexity of controller circuit
and components also increase.
2-Level output 3-Level Output 5-Level Output

5. MULTI LEVEL INVERTER TOPOLOGIES
 The elementary concept of a multilevel converter to achieve higher power
is to use a series of power semiconductor switches with several lower
voltage dc sources to perform the power conversion by synthesizing a
staircase voltage waveform.
 Capacitors, batteries, and renewable energy voltage sources can be used as
the multiple dc voltage sources.
 however, the rated voltage of the power semiconductor switches depends
only upon the rating of the dc voltage sources to which they are connected.
 There are several topologies of multilevel inverters available. The
difference lies in the mechanism of switching and the source of input
voltage to the multilevel inverters. Three most commonly used multilevel
inverter topologies are:
• Cascaded H-bridge multilevel inverters
• Diode Clamped multilevel inverters
• Flying Capacitor multilevel inverters.
5

6. MULTI LEVEL INVERTER TOPOLOGIES
DIODE CLAMPED MULTI LEVEL INVERTER
 This topology uses clamping diodes in order to limit the voltage stress of power devices.
 It was first proposed in 1981 by Nabae, Takashi and Akagi.
 A k level diode clamped inverter needs
• (2k – 2) switching devices,
• (k – 1) input voltage source and
• (k – 1) (k – 2) diodes in order to operate.
 Vdc is the voltage present across each diode and the switch.
Three level diode clamp multi-level inverter (one leg) Switching states in one leg of the three-level diode clamped inverter

7. FLYING CAPACITOR MULTILEVEL INVERTER
 This configuration is quite similar to previous one except the difference that here flying
capacitors is used in order to limit the voltage instead of diodes.
 The input DC voltages are divided by the capacitors here.
 The voltage over each capacitor and each switch is Vdc.
 A k level flying capacitor inverter requires.
• (k - 1) x (k - 2)/2 auxiliary capacitors per phase leg
• (2k – 2) switches and
• (k – 1) number of capacitors in order to operate.
 Switching state is same as diode clamped Multilevel Inverter
Advantages of Flying Capacitor Multilevel Inverters
• Static var generation is the best application of Capacitor Clamped
Multilevel Inverters.
• For balancing capacitors’ voltage levels, phase redundancies are
available.
• We can control reactive and real power flow
Disadvantages of Flying Capacitor Multilevel Inverters
• Voltage control is difficult for all the capacitors
• Complex startup
• Switching efficiency is poor
• Capacitors are expansive than diodes
Three level Flying Capacitor multi-level inverter (one leg)

8. CASCADE H-BRIGDE MULTI LEVEL INVERTER
 Each cell contains one H-bridge and the output voltage generated by this multilevel inverter is
actually the sum of all the voltages generated by each cell i.e. if there are k cells in a H-bridge
multilevel inverter then number of output voltage levels will be 2k+1.
Advantages of Cascade H Bridge Multilevel Inverters
• Output voltages levels are doubled the number of
sources
• Manufacturing can be done easily and quickly
• Packaging and Layout is modularized.
• Cheap
Disadvantages of Cascade H Bridge Multilevel
Inverters
• Every H Bridge needs a separate dc source.
• Limited applications due to large number of sources.
Cascaded inverter circuit topology and its associated waveform

9. COMPARISON OF DIFFERENT MULTILEVEL
INVERTER TOPOLOGIES
S.No. Topology Diode
Clamped
Flying
Capacitor
Cascaded
1 Power semiconductor
switches
2(m-1) 2(m-1) 2(m-1)
2 Clamping diodes per
phase
(m-1)(m-2) 0 0
3 DC bus capacitors (m-1) (m-1) (m-1)/2
4 Balancing capacitors per
Phase
0 (m-1)(m-2)/2 0
5 Voltage unbalancing Average High Very small
6 Applications Motor drive
system,
STATCOM
Motor drive
system,
STATCOM
Motor drive
system, PV,
fuel cells,
battery system

10. Sinusoidal PWM Technique
 In this technique, an isosceles triangle carrier wave of frequency fc is compared with the fundamental
frequency fr sinusoidal modulating wave, and the points of intersection determines the switching points of
power devices.
 Two important parameters of the design process are
• Amplitude Modulation Index Ma=
𝐕𝐫
𝐕𝐜
where Vr = Peak amplitude of reference control signals
Vc = Peak amplitude of the Triangular carrier wave.
• Frequency Modulation Index Mf =
𝐟𝐜
𝐟𝐫
where fc = frequency of the carrier wave
fr = reference sinusoidal signal frequency.
 Ma determines the magnitude of output Voltage
 fr controls the frequency of output voltage
 fc determines switching frequency of power semiconductor devices. 10

11. Sinusoidal PWM Technique
 Types of Multiple Carrier-based SPWM Techniques:
Sinusoidal PWM can be classified according to carrier and modulating signals.
This work used the intersection of a sine wave with a triangular wave to generate firing
pulses.
There are many alternative strategies, such as:
I. In-Phase Disposition (PD)
II. Phase Opposition Disposition (POD)
III. Alternative Phase Opposition Disposition (APOD)
I. In-Phase Disposition (PD):
In this technique, All the triangular carrier waves are In-Phase with each other.
11

12. II. Phase Opposition Disposition (POD):
In this technique, the carrier signal above Zero reference are In-Phase but Phase shifted by 180°
from those carrier signals which are below zero reference.
III. Alternative Phase Opposition Disposition (APOD):
In this method, each carrier signal is phase shifted by 180° from the adjacent carrier signal.
12

13. MODELING OF PHASE DISPOSITION(PD)
MODULATION TECHNIQUE
GENERATION OF MODULATING SINE WAVE
In order to generate fundamental component of output voltage at 50Hz frequency, the frequency
of reference sine wave is set to 50Hz itself.
13
This option is used to apply
PHASE SHIFT in Sine wave
in terms of RADIANS.
120° = 2*pi/3
240° = -2*pi/3
This option is
used to apply
desired
frequency of Sine
wave in terms of
RADIANS

14. MODELING OF PHASE DISPOSITION(PD)
MODULATION TECHNIQUE
GENERATION OF TRIANGULAR CARRIER WAVE
Let the switching frequency, fs = 1.1 kHz
Fundamental(Output) Frequency, fr = 50 Hz
Hence, Frequency Modulation ratio, Mf = 22(
𝑓 𝑠
𝑓 𝑟
) which means there exist 22 cycles of triangular wave
for each cycle of Sine wave.
Time Period, T 𝑠 =
1
𝑓 𝑠
=
1
1100
= 9.09 * 10-4 sec.
Let, 𝑥 =
𝑇 𝑠
4
= 0.0002273 sec.
14

15. MODELING OF PHASE DISPOSITION(PD)
MODULATION TECHNIQUE
GENERATION OF FIRING PULSES
 PD SPWM GENERATION FOR 3-LEVEL INVERTER :
• Three level pulse width modulated waveforms can be generated by sine-carrier PWM.
• Sine carrier PWM is generated by comparing the three reference control signals (one for each phase) with two
triangular carrier waves.
Vdc/2 , Vref,i > Vtri,1
Vio = 0 , Vtri,1 > Vref,i > Vtri,2 Where i= a, b or c phase
-Vdc/2 , Vtri,2 > Vref,
Simulated SPWM output for 3-Level Inverter 15

16. MODELING OF PHASE DISPOSITION(PD)
MODULATION TECHNIQUE
GENERATION OF FIRING PULSES
 PD SPWM GENERATION FOR 3-LEVEL INVERTER :
Simulink Model for 3-Level PD SPWM Generation Firing Pulses for Upper & Lower Switches for a-Phase of 3-Level inverter
16

17. SIMULATION MODELS OF DIODE CLAMPED THREE LEVEL
INVERTER
Specifications(For both 3-Level & 5-Level Inverter):
• Supply Voltage = 200V
• Fundamental Frequency (fr) = 50 Hz
• Switching Frequency (fs) = 1.1 KHz
• Amplitude Modulation Index (Ma) = Variable
• Frequency Modulation Index (Mf) = 22
Simulink Model of THREE Level Diode Clamped SPWM Inverter 17

18. SIMULATION RESULTS
Simulated Line voltage of 3-Level diode clamped inverter
Harmonic Spectrum of 3-Level diode clamped inverter for R= 25Ω/phase and ma=0.9
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19. 19

20. SIMULATION RESULTS
Simulated Line voltage of 2-Level diode clamped inverter
Harmonic Spectrum of 2-Level diode clamped inverter

21. HARDWARE IMPLEMENTATION
MOSFET DRIVE CIRCUIT
 A gate driver is used when a pulse width- modulation (PWM) controller cannot
provide the output current required to drive the gate capacitance of the MOSFET.
 Gate drivers may be implemented as dedicated ICs, discrete transistors, or
transformers.
 They can also be integrated within a controller IC.
 Partitioning the gate-drive function off the PWM controller allows the controller to
run cooler and be more stable by eliminating the high peak currents and heat
dissipation needed to drive a power MOSFET at very high frequencies.
21

22. COMPONENTS USED
 MOSFET (IRF 840)
 TRANSISTER (BD 139)
 OPTOCOUPLER (PC 817)
 VARISTOR (MOV-20D751K)
 ZENER DIODE
 RESISTANCE
 CAPACITOR
 DIODE
APPARATUS USED IN TESTING
 PULSE GENERATOR
 DSO
 POWER SUPPLY
 LOAD
22

23. TESTING OF MOSFET DRIVE CIRCUIT
23

24. ARDUINO
 Arduino Uno is a microcontroller board based on the ATmega328P (datasheet).
 It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6
analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP
header and a reset button.
 It contains everything needed to support the microcontroller; simply connect it to a
computer with a USB cable or power it with a AC-to-DC adapter or battery to get
started "Uno" means one in Italian and was chosen to mark the release of Arduino
Software (IDE) 1.0.

25. IMPLEMENTED HARDWARE AND RESULT
25

26. COMPARISON OF CONVENTIONAL TWO LEVEL
INVERTERS AND MULTILEVEL INVERTER
S.No. Conventional Inverter Multilevel Inverter
1 Higher THD in output voltage Low THD in output voltage
2 More switching stresses on
devices
Reduced switching stresses on
devices
3 Not applicable for high voltage
applications
Applicable for high voltage
applications
4 Higher voltage levels are not
produced
Higher voltage levels are
produced
5 Since dv/dt is high, the EMI
from system is high
Since dv/dt is low, the EMI from system is low
6 Higher switching frequency is
used hence switching losses is
high
Lower switching frequency can
be used and hence reduction in
switching losses
7 Power bus structure, control
schemes are simple
control scheme becomes
complex as number of levels
increases
8 Reliability is high Reliability can be improved,
rack swapping of levels is
possible
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27. ADVANTAGES OF THREE LEVEL INVERTER
 The multilevel inverters produce common mode voltage, reducing the
stress of the motor and don’t damage the motor.
 Multilevel inverters can draw input current with low distortion.
 The multilevel inverter can operate at both fundamental switching
frequencies that are higher switching frequency and lower switching
frequency. It should be noted that the lower switching frequency means
lower switching loss and higher efficiency is achieved.
 Selective harmonic elimination technique along with the multi level
topology results the total harmonic distortion becomes low in the output
waveform without using any filter circuit.
 All of the phases share a common dc bus.
 Reactive power flow can be controlled.
27

28. DISADVANTAGES OF THREE LEVEL INVERTER
 Need high voltage rating diodes to block the reverse
voltages.
 circuit increases with the increase in the number of
output voltage levels. Extra clamping diodes required
are (n-1)(n-2) per phase.

29. 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.
 Variable speed motor drives.
 High voltage system interconnections.