High Efficient Single Stage Single Phase Boost

Inverter with Minimized Harmonic Distortion

1
T.Dineshkumar, 2M.Mathankumar, 3Dr.M.Sundaram
1,2
Assistant Professor, Dept. of EEE, 3Associate Professor, Dept. of Robotics and Automation Engineering,
1,2
Kumaraguru College of Technology, 3PSG College of Technology,
1,2,3
Coimbatore, Tamilnadu
1
dinesh161190@gmail.com, mathankumarbit@gmail.com, 3msm@rae.psgtech.ac.in
2

Abstract – Solar energy is an abundant renewable energy In the conventional renewable energy source
source from sunlight which can be used to charge a battery. conversion system, dc supply taken from the solar panel is
The battery voltage is converted into 230V ac supply using boosted into high level voltage by using dc-dc boost
inverter for driving single phase load applications like home converter and then it is converted into ac supply by using
appliances. The output of the conventional voltage source
inverter is lower than its input and is used to drive the loads
dc-ac inverter [2][3]. Then the inverter output voltage is
after removing the ripples by using filtering circuit. The main stepped up into 230V ac supply by using step up
feature of the boost inverter is it will produce an ac output transformer after removing the ripples by using filtering
voltage higher than the input dc supply depending on the circuit and is then used to drive the loads.
instantaneous duty cycle. The output of boost inverter can be
used to drive the autonomous loads and home appliances In renewable energy conversion system, the
without any filter. The main advantages are low cost, less number of power processing stages is high as given in the
number of switches used, compact size and reduce the power Fig. 1. Due to this, the losses are more and conversion
processing stages into single stage. efficiency gets reduced. By using the boost inverter
topology the power processing stages can be reduced into
Keywords: Solar energy, Boost inverter, Inverter, Filter, Total
harmonic distortion.
single stage which is shown in Fig. 2. The output of the
boost inverter can be used to drive the loads without any
I INTRODUCTION filter directly [4][5].

Nowadays the requirement of electrical energy is

more than the generation of electrical energy due to the
growing usage of electrical power. In order to overcome
that, generation of electrical power should be increased but
it is difficult to implement in the current situation because
only 7% of the energy is produced by renewable energy
sources, 87% of the energy is yielded from burning of fossil
fuels such as natural gas, oil and coal, 6% of the energy is
Fig.1.Block diagram of conventional Renewable energy
produced from nuclear fuels which is going to be depleted conversion system
by the end of 22nd century [1].
II THE BOOST INVERTER MODEL
In our country, 70% of the energy is produced by
major thermal plants by burning coal. It is projected that The boost inverter facilitates dc-ac conversion by
‘natural uranium fuel’ is expected to last for 50 years, ‘oil’ connecting the load across two dc-dc converters. The circuit
for 100 years, ‘natural gas’ for 150 years and ‘coal’ for 200 diagram of single stage boost inverter circuit with R load is
years only [1]. Electrical energy can be provided to future given in Fig.3. The dc-dc converters output is sinusoidal
generation only by using electrical energy efficiently, unipolar voltage. The dc-dc converters produce dc biased
improving the conversion processes efficiently and by the sine wave output even though each converter produces
production of electrical energy from the renewable energy unipolar voltage only. These two converter’s outputs are
sources [1]. The boost inverter can efficiently convert 105V 180 degree out of phase, which increase the voltage drop
dc to 310V ac without any filter in which the 105V dc across the load [4].
supply is generated from solar panels. Its conversion process
efficiency is very high whereas the output of the The principle of operation of bidirectional boost
conventional inverter is lower than its input. dc-dc converter is as shown in the Fig.3. There are two
modes of operation in every cycle of output voltage. If
switch1 is closed and switch2 is open, the inductor current
978-1-5090-3498-7/16/$31.00 ©2016 IEEE

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(iL) increases quite linearly where diode is reverse biased. obtain maximum voltage across the load it is required to
So capacitor voltage V1 is discharge into output side. keep the duty cycle near to unity [4].

III SIMULATION RESULTS AND DISCUSSIONS

A. MATLAB simulation circuit for Boost inverter

The Simulink model of single phase boost inverter

circuit is shown in Fig.4. It consists of four IGBT switches
(S1, S2, S3 and S4) and two inductors connected with the
input DC source. Four feedback diodes (D1, D2, D3 and
D4) are connected across the IGBT switches. Two
Fig.2.Block diagram of single stage boost inverter capacitors (C1 and C2) are connected across each boost
converter, whose output voltages are 180 degree out of
phase with each other. The resistive load R is connected
across the boost converters. The parameters of boost
inverter with resistive load is shown in table-I.

When switches S1 and S3 are turned on, inductor

L1 gets charged, inductor L2 gets discharged and capacitor
C2 gets charged through the inductor L2, DC input and
switch S3 loop. Similarly capacitor C1 gets discharged
through resistor R, switch S3 and S1, inductor L1and L2 i.e.
the capacitor C1 gets discharged to the load.
Fig.3.Single stage boost inverter circuit with R load
TABLE I
Parameters of boost inverter with resistive load
If switch1 is open and switch2 is closed, the inductor current
(iL) flows through capacitor and load. So, the current (iL) Parameters Values
decreases linearly while capacitor C is recharged. The 180 Inductor, L=L1=L2 (Mh) 8
degree phase shift can be attained by simultaneously
switching the diagonal switches. Capacitor, C=C1=C2 (µF ) 775

Resistor, R (Ω) 200

The input-output voltage relationship is given by
Input DC Voltage, Vin (V) 105

Output AC Voltage, Vo (V) 305

Rms value, Vrms (V) 215

Switching Frequency, fs
10
(KHz)

Where, D is the duty cycle.

The output voltage can be derived as

Fig.4. Boost inverter with Resistive Load

From the above equations the gain characteristics When switches S2 and S4 are turned on, the
of boost inverter can be drawn in which one significant operation is just opposite to the first mode of operation, the
information to be noted is that when the duty cycle D=0.5, inductor L2 gets charged and inductor L1 gets discharged.
the output voltage of boost inverter will be zero. In order to Then, the capacitor C1 gets charged via DC input, inductor

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L1 and switch S2 loop. Simultaneously, capacitor C2 gets
discharged via the resistor R, switches S2 and S4, inductors
L1 and L2 which means that capacitor voltage is discharged
into the load.

Fig.5. Voltage and current waveforms of Boost inverter with resistive load Fig.6. Boost inverter with Motor Load

In order to trigger the switches, sinusoidal pulse

width modulation technique (SPWM) is used [6][7], in
which carrier triangular signal of 10 kHz frequency is
compared with reference sinusoidal signal of 50 Hz
frequency with the modulation index 0.7. The inverter
output voltage and current waveform are shown in the Fig.5.
The magnitude of the voltage is 310V which is free from
ripples, distortions such that pure sinusoidal wave is
obtained and the magnitude of current is 1.52A.

B. Boost Inverter with motor load

The Simulink model of single phase boost inverter with

motor load circuit diagram is shown in Fig.6. It consists of
same elements as seen in the model with resistive load, Fig.7. Voltage and Current waveforms of boost inverter with motor load
whereas parameter values are changed corresponding to
RLE load which is shown in table-II. In the previous model, The electrical parameters of the motor are shown in
a simple resistive load was used to analyze the performance Fig.7, in which first curve shows output voltage of boost
of boost inverter. Now, to implement this boost inverter in inverter which is given as input to motor, second curve
real time system, the resistive load is replaced by an shows input current of the motor and third curve shows
induction motor used for pumping application. The output output current of the motor with respect to time. The
of boost inverter is given to the motor and various motor magnitude of input voltage of the motor is 250V. The
parameters such as mechanical parameters and electrical magnitude of output current is 15A.
parameters have been obtained.
C. Comparison of Boost inverter and conventional
TABLE II
Parameters of boost inverter with motor load inverter

The boost inverter is compared with conventional

Parameters Values method with reference to its output for same type of load.
Inductor, L=L1=L2 (Mh) 5 Fig.8 shows that speed of the motor is around 1400 rpm in
Capacitor, C=C1=C2 (µF ) 1900
both topologies. So, the boost inverter topology output is
merely same as that of pure sinusoidal source. Torque
Input DC Voltage, Vin(V) 105
comparison is shown in the Fig.9. In both cases, torque is
Output AC Voltage, Vo (V) 250 around zero at no load condition. So it can be concluded that
Load, RLE (Induction motor) ½ HP boost inverter can be used to drive the load directly without
Rated Speed, Ns (rpm) 1500 filter circuit.
Actual Speed, NA (rpm) 1400
Torque, (N-m) 0

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 -

Fig.8. Speed comparison between conventional and proposed method

Fig.10. THD analysis of Boost inverter for resistive load

Fig.9. Torque comparison between conventional and proposed method

D. THD analysis of Single stage boost inverter

In order to get the pure sinusoidal signal, filter

should be used in the conventional inverter whereas boost
inverter has pure sinusoidal output without any filter. The
total harmonic distortion (THD) is simulated for single stage
boost inverter with R load and motor load is as shown in Fig.11. THD analysis of Boost inverter with motor load
Fig.10 and Fig.11 respectively.

The total harmonic distortion of conventional IV CONCLUSION

inverter can be reduced to zero if the filter design is more
accurate. In case of boost inverter topology without any This paper boon a new type of dc-ac converter
filter, THD is reduced to 2.89% which is more advantageous normally referred as boost inverter. The circuit operation
than the conventional inverter. The THD of boost inverter has been simulated and analyzed. In UPS design this boost
with motor load is 1.51%. It confirms that the single stage inverter is applicable whenever an ac voltage is larger than
boost inverter can be used to drive the load effectively with the dc link voltage is needed, without second power
minimum harmonic distortion without any filter. conversion stage. This prototype effectively utilizes the
power and minimizes harmonic distortions in a compact and
cost effective way. This system is highly suitable for
autonomous water pump applications and home appliances.

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