A hybrid converter topologies which can supply simultaneously AC as well as DC from a single DC source. The new Hybrid Converter is derived from the single switch controlled Boost converter by replacing the controlled switch with voltage source inverter (VSI). This new hybrid converter has the advantages like reduced number of switches as compared with conventional design having separate converter for supplying AC and DC loads, provide DC and AC outputs with an increased reliability, resulting from the inherent shoot through protection in the inverter stage. For controlling switches PWM control, based upon unipolar Sine-PWM is described.

1. SUBMITTED BY-:
NAME-DEBASIS MOHANTY
REGD NO-14020081
BRANCH-ELECTRICAL ENGINEERING
SECTION-B’2

2. Abstract:
A hybrid converter topologies which can supply
simultaneously AC as well as DC from a single DC source.
The new Hybrid Converter is derived from the single switch
controlled Boost converter by replacing the controlled switch
with voltage source inverter (VSI). This new hybrid converter
has the advantages like reduced number of switches as
compared with conventional design having separate
converter for supplying AC and DC loads, provide DC and
AC outputs with an increased reliability, resulting from the
inherent shoot through protection in the inverter stage. For
controlling switches PWM control, based upon unipolar
Sine-PWM is described.

4.  INTRODUCTION
 TECHNOLOGY USED
 ARCHITECTECTURES SUPPLYING DC AND AC LOAD
 COMPONENT REQUIRED IN BDHC
 DESCRIPTION OF COMPENETS USED
 DERIVATION OF BDHC TOPOLOGY
 WORKING PRINCIPLE
 CIRCUIT OPERATION OF BDHC
 HARD WARE CIRCUIT OF BDHC
 ADVANTAGE
 APPLICATION
 CONCLUSION

5. INTRODUCTION
Nanogrid architectures are greatly incorporated in the modern
power system. In this system there is DC as well as AC loads
supplied by different kinds of energy sources using efficient power
electronic converters [2]. Fig.1 shows the schematic of the system
in which single DC source supplies both AC and DC loads. Fig.
1(a) shows the conventional architecture in which DC and AC load
supplied by separate DC-DC converter and DC-AC converter from
a single DC source respectively Whereas in Fig. 1(b) referred as
hybrid converter in which a single converter stage perform both
operations. Such multi-output converters is very well suitable for
systems with better power processing density and improved
reliability for supplying simultaneous ac as well as dc outputs.

6. This hybrid converter has the property of higher power
processing capability and improved reliability resulting
from the inherent shoot through protection. This paper
investigates the use of single boost stage architecture to
supply hybrid loads. The conventional VSI in Hybrid
converter would through. Also misgating turn-on of switches
may take place due to spurious noise resulting in damage of
switches. For a compact system, spurious signal generation
takes place commonly. So VSI in such application needs to
be highly reliable with appropriate measures against shoot-
through and EMI induced misgating.

7. Technology used
 DC Nanogrid
 Voltage source inverter(VSI)
 Boost-Derived Hybrid Converter
 shoot-through state

8. Figure 1: Architectures supplying DC and AC load from a single DC
source. (a) Dedicated power converter based architecture and (b) Hybrid
converter based architecture.

9. Component Required
 Dc source
 Zero source inverter
 Unipolar SPWM(sine pulse width modulation)
 Inductor
 Diode
 Mosfet
 Capacitor
 Ac load
 Dc load

10. Description of components
 ZERO SOURCE INVERTER
A zero source inverter is a type of power inverter, a that
converts direct current to alternating current. It
functions as a buck-boost inverter without making use
of DC-DC converter bridge due to its unique circuit
topology.

11. Disadvantages
Typical inverters (VSI and CSI) have few disadvantages. They are listed as,
•Behave in a boost or buck operation only. Thus the obtainable output voltage
range is limited, either smaller or greater than the input voltage.
•Vulnerable to EMI noise and the devices gets damaged in either open or short
circuit conditions.
•The combined system of DC-DC boost converter and the inverter has lower
reliability.
•The main switching device of VSI and CSI are not interchangeable.
Advantages of ZSI
The advantages of Z-source inverter are listed as follows,
•The source can be either a voltage source or a current source. The DC source of a
ZSI can either be a battery, a diode rectifier or a thyristor converter, a fuel cell stack
or a combination of these.
•The main circuit of a ZSI can either be the traditional VSI or the traditional CSI.
•Works as a buck-boost inverter.
•The load of a ZSC can either be inductive or capacitive or another Z-Source
network.

12. Unipolar spwm
 Pulse-width modulation uses a rectangular pulse wave
whose pulse width is modulated resulting in the
variation of the average value of the waveform. If we
consider a pulse waveform f ( t ) {display style f(t)} ,
with period T { T} , low value y min {display style
y_{text{min}}} , a high value y max {display style
y_{text{max}}} and a duty cycle D

13. Voltage regulation
Main article: Switched-mode power supply
•PWM is also used in efficient voltage regulators. By switching voltage to the
load with the appropriate duty cycle, the output will approximate a voltage at
the desired level. The switching noise is usually filtered with an inductor and
a capacitor.
One method measures the output voltage. When it is lower than the desired
voltage, it turns on the switch. When the output voltage is above the desired
voltage, it turns off the switch.
• SPWM (Sine–triangle pulse width modulation) signals are used in micro-
inverter design (used in solar and wind power applications). These switching
signals are fed to the FETS that are used in the device. The device's efficiency
depends on the harmonic content of the PWM signal. There is much
research on eliminating unwanted harmonics and improving the
fundamental strength, some of which involves using a modified carrier signal
instead of a classic saw tooth signal in order to decrease power losses and
improve efficiency. Another common application is in robotics where PWM
signals are used to control the speed of the robot by controlling the motors.

14. MOSFET as a Switch
We saw previously, that the N-channel, Enhancement-mode
MOSFET (e-MOSFET) operates using a positive input voltage and
has an extremely high input resistance (almost infinite) making it
possible to interface with nearly any logic gate or driver capable
of producing a positive output.

15. Figure 2: (a) Conventional boost converter, (b)Proposed Boost-Derived Hybrid converter obtained
by replacing with a single phase bridge network.

16. II. BOOST-DERIVED HYBRID
CONVERTER
A. PROPOSED CIRCUIT MODIFICATION
Conventional boost circuit is having two switches, one is a
controllable switch (controls the duty cycle) and other can be
implemented using a diode. Hybrid converter can be realized
by replacing controllable switch in the boost circuit with a
voltage source inverter, either single phase or three phase VSI.
The resulting converter called as Boost Derived Hybrid
converter (BDHC) [1].

17. B.DERIVATION OF BDHC TOPOLOGY
Control-switch of a boost converter (shown in Fig. 2(a)) is
replaced with a single phase bridge network switches (S1-
𝑆4) to obtain Boost Derived Hybrid Converter (shown in
Fig. 2(b)).AC and DC outputs are controlled using same set
of switches (S1-𝑆4). So challenges involved in the
operation of BDHC are, (a) defining duty cycle (Dst ) for
boost operation modulation index (Ma ) for inverter operation
(b) control and channelization of input DC power to DC as
well as AC loads (c) Determination of voltage and current
stresses various switches.

18. WORKING PRINCIPLE
In the operation of hybrid converter is concerned this is
equivalent to switching on controllable switch of the
conventional boost converter. The ac output is controlled
using a modified version of the unipolar sine width
modulation. The BDHC during inverter operation has the
same circuit states as the conventional VSI. The switching
scheme should ensure that the power transfer with
source occurs only during is positive.
The BDHC has three distinct switching states as described
below:

19. A. INTERVAL 1: SHOOT-THROUGH INTERVAL
Fig. 3(a) shows the equivalent circuit during shoot- through
interval. In this interval we adjust the duty cycle for the boost
operation by turning on both switches of any particular leg at the
same time. Diode D is reverse biased during this interval.
Inverter current circulates within the bridge switches.
B. INTERVAL 2: POWER INTERVAL
Fig. 3(b) shows the equivalent circuit during power interval.
Here inverter current enters or leaves through switch node
terminal S. Switches S1-S2 or S3-S4 turned. Diode is forward
biased. Power is delivered to both ac and dc loads.

20. C. INTERVAL 3: ZERO INTERVAL
Fig. 3(c) showing the equivalent circuit during zero interval.
Here diode is in forward biased condition and the power is
delivered to dc load. Inverter current circulates within the bridge
switches.

21. Figure 3: (a) Shoot-Through interval,

22. (b) Power interval
(c) Zero interval.

24. Vdc out
Vdc in
1
1-Dst
The switching strategy must satisfy the following
constraint:
Ma + Dst ≤ 1.

25. DC and AC Output Power Expressions:
the expressions for output dc (Pdc) as well as ac power (Pac) can be derived as
follows:
Pdc= v2
dcin (Rdc∗(1− Dst)
2
0.5 ∗Vdcin
2
∗Ma
2
)
(Rac∗(1− Dst)2
)Pac= V2
ac in

26. IV. LITERATURE REVIEW
A. EXTENDED BOOST Z-SOURCE INVERTER
F. L. Luo et al proposes the extended boost Z-source inverters
in which, the original Z-source inverter the boosting capability is
very less so that it is not suitable for applications which requires
very high boost demand. Thus an extended boost Z-source
inverter is proposed to overcome the limitations of classical Z-
source inverter. The new topologies developed in this paper are
same as that of the methods used in classical Z-source inverter.
The basic topology of extended boost ZSI is obtained when the
dc source and the inverter sharing same ground point produces
discontinuous current. To extend the boosting capability four new
converter topologies are proposed namely diode assisted boost
and capacitor assisted boost topology [4].

27. .
A diode assisted topology requires one inductor, one capacitor
and two diodes in addition to the existing topology where
capacitor assisted boost topology require one inductor, two
capacitors and one diode. A hybrid system is also developed by
combining capacitor assisted boost topology and diode assisted
topology. Here the number of stages is very larger than the other
boost topologies and there occurs high current stress on the
switches. So a suitable modulation method is selected by
distributing the shoot- through current to the inverter bridge to
reduce the current stress but switching losses still exists.

28. C. DERIVATION ANDCHARACTERIZATION
OF SWITCHED-BOOST INVERTER
 S.Upadhyay et al proposes an alternative implementation of Z-
source inverter [5]. The Z-source inverter uses a LC impedance
network which is connected between the dc source and the voltage
source inverter. The size of the converter increases due to the use of
impedance which consists of two inductors and two capacitors.
When the impedance network is perfectly symmetrical, then the
stable operation is achieved. The passive components used is less
compared to ZSI while active components are present in a large
amount for the proposed switched boost inverter (SBI) as shown in
fig. 4. This topology cannot be used to supply ac and dc loads
simultaneously because the two capacitors it possesses will not have
equal loads across them. Unmatched loads results in unstable
operation. The SBI can also generate an ac output voltage that is
either the greater or less than the input dc voltage.

29. c
Figure 4: Structure of the proposed SBI-based AC load and DC load

30. Fang Zheng Peng et al proposes different boost control
methods. The maximum boost voltage can be achieved using
maximum boost control method [7]. Reducing the voltage
stress is the most important in the control of Z-source
inverter under a desired voltage gain. The voltage stress is
minimized by minimizing the boost factor B and by
maximizing the modulation index M. The maximum boost
voltage control methods maintains the six active states
unchanged as the traditional carrier based PWM and all the
zero states to shoot- through zero states, thus maximum
output voltage gain can be obtained by the same modulation
index. For increasing the modulation index, third harmonic
injection method is used. The shoot-through duty cycle
repeats for every but it does without affecting the active
states.

31. Figure 5: Voltage-stress comparison of different control methods.

32. E. SWITCHED INDUCTOR Z-SOURCE INVERTER

33. SYNCHRONOUS-REFERENCE-FRAME-BASED
CONTROL OF SWITCHED BOOST INVERTER FOR
STANDALONE DC NANOGRID APPLICATIONS
 Ravindranath Add a et al propose a switched boost inverter
suitable for standalone dc nanogrid applications as shown in
fig. 7. Switched boost inverter is a single stage power converter
which can supply simultaneous ac and dc loads from a single
dc input. This topology also possesses robust electromagnetic
interference noise immunity, which is achieved by allowing
shoot through of the inverter leg switches..

34. A power electronic interface called a switched boost inverter is
used for dc nanogrid applications and also a dq synchronous-
reference-frame-based controller for SBI is used to control both
dc and ac bus voltages of the nanogrid to their respective
reference values under steady state as well as under dynamic
load variation [9]. Thus SBI has several advantages comparing
to traditional two stage DC to AC conversion system.
Figure 7: Structure of the proposed SBI-based dc nanogrid.

35. I. HIGH EFFICIENCY DC-DC
CONVERTER WITH HIGH VOLTAGE
GAIN REDUCED SWITCH STRESS
Rong-Jong Wai proposes a high efficiency dc-dc converter with
high voltage gain and reduced switch stress [3]. The conventional
boost converter does not provide a high voltage gain because of the
losses associated with the inductor, filter capacitor, switch and
output diode. So, a coupled inductor is used for improving the
voltage ratio. But it requires high voltage rated devices because of
the switch surge voltage caused by the leakage inductor. Even
under extreme duty cycle, it causes serious reverse recovery
problems and increases the rating of output diode. Under this
situation, electromagnetic interference problem is severe and
efficiency is decreased

36. In order to protect the switch devices, either a high voltage rated
device with higher resistance or a snubber circuit is usually adopted
to deplete the leakage energy. In the proposed topology, a high
efficiency dc-dc converter with high voltage gain and reduced switch
stress to provide a constant dc voltage. A three winding coupled
inductor is used to increase the voltage gain and to enhance the
utility rate of magnetic core. The problem of leakage inductor and
reverse recovery is solved by maintaining the delay time formed with
the cross of primary and secondary currents of coupled inductor. The
output diode is replaced with schottky diode for reduced switching
losses. Thus converter topology is highly efficient and a
closed-loop control methodology is used to overcome the voltage
drift problem of the power source under the variation of loads.

37. Advantage
 Smaller in size
 Less cost
 At simultaneous period both ac and dc can be get
 High efficiency
 Reliability in nature
 Switching loss is less

38. Application
Military
Aerospace
nanogrid

39. A power electronic interface called a switched boost inverter is
used for dc nanogrid applications and also a dq synchronous-
reference-frame-based controller for SBI is used to control both dc
and ac bus voltages of the nanogrid to their respective reference
values under steady state as well as under dynamic load variation
[9]. Thus SBI has several advantages comparing to traditional two
stage DC to AC conversion system.
Figure 7: Structure of the proposed SBI-based dc nanogrid.

40. CONCLUSION
This paper proposes new Hybrid converter topologies which can
supply simultaneously both DC and AC loads from a single DC
supply. The hybrid converter topology discussed in this paper is
Boost Derived Hybrid Converter (BDHC) .The proposed hybrid
converter has the following advantages, shoot-through condition
does not cause any problem on working of the circuit hence
improves the reliability of the system, Implementation of dead
time circuitry is not needed, Independent control over AC and DC
output and the converter can also be adapted to generate AC
outputs at frequencies other than line frequencies by a suitable
choice of the reference carrier waveform. Limitations on voltage
gain can be achieved by BDHC topology.