A Distinct Pseudo-Random Carrier Modulation Apporach for a Boost Converter

Anant Kumar Verma M.tech(student),

Dept of Electrical Engineering, DIT University, Dehradun, India Anant_verma12@hotmail.com

Gagan Singh Head of Department, Electrical

Engineering, DIT University, Dehradun, India

gaganus@gmail.com

Abstract— Pseudorandom carrier scheme is a distinct approach for analysis of various demerits (Discrete frequency harmonics, Electromagnetic interference, audible switching noise etc.) occurring due to the switching frequency of a semiconductor device (MOSFET,IGBT etc.) in Power electronic system (PES). In the proposed scheme random synthesis of two triangular carrier waves opposite in phase are randomly selected by using 12 bit PN-Sequence generator on the basis of “0” and “1” bits of a 12-bit sequence (called as Pseudorandom binary (PBRS) sequence random bits).Train of switching pluses are generated using Pseudorandom carrier and a reference signal to control the BOOST converter output levels.

Keywords- Pseudorandom carrier, Boost converter , IGBT, PN-sequence generator, FFT analysis.

I. INTRODUCTION

In last few decades there has been an intensive research going on in the field of PULSE-WIDTH modulation (PWM) techniques. A large variety of concepts and methods have been developed till now for various performance analyses. Various home appliances like-air conditioners, washing machine, refrigerators, home inverters etc are utilizing constant frequency PWM techniques. The study about power electronics converters reveals that there have been an audible switching noise, Electromagnetic interference (EMI) and various harmonic effects occurring in the PES (Power Electronic System) due to the switching frequency of the semiconductor switch (IGBT,MOSFET etc.). A range of switching frequency of up to 20 KHz can diminish the effect of audible noise to very good extent.

Although in a PES switching loss are increased but noise problem is reduced by using PWM techniques. A random PWM scheme (RPWM) [2] is presently a very familiar technique for reducing the switching noise by driving PES with a low switching frequency scheme. A low cost is really important phenomenon in the realization of the PES as RPWM is the optimized scheme which can be developed on hardware using microcontroller very easily .There have been many RPWM [2],[3],[6] schemes reported which can be generally classified in to three groups as:

• Randomized Pulse Position Modulation.

• Randomized Switching Frequency Modulation.

• Hybrid Random Modulation. In the entire above three schemes most widely applicable

scheme to PES is the randomized switching frequency modulation scheme. In this scheme to be very brief, a triangular carrier wave is taken and the slope of the triangular carrier wave is randomly varied.

Under survey of these schemes a pseudorandom triangular carrier modulation scheme is proposed by combined efforts of the research team of four people Young-Cheol Lim , Seog-Oh Wi , Jong-Nam Kim, and Young-Gook Jung who developed the scheme for analysis of H-Bridge multilevel inverter (HBML) and they studied its effects of Harmonics as well implemented a hardware structure of the proposed scheme.

II. PSEUDORANDOM SCHEME

In this novel approach we have to struggle hard for combining the two fixed frequency triangular waveforms which are out of phase from each other for developing the pseudorandom carrier frequency by using a PN-sequence generator which is 12 bit long for random selection of the triangular waveforms. Our sequence generator will exactly behave as a Shifter register which generates random binary bits for the selection of triangular waveforms in real time system resulting in a pseudorandom carrier.

As the name suggests the Pseudorandom itself explain the meaning that the resultant waveform we be a triangular wave of random frequency. Our simulation study is done to implement the proposed scheme using MATLAB for controlling a DC-DC converter (boost converter).In Proposed pseudorandom scheme number of bits utilization for random selection are as 8bits , 10 bits ,12 bits[6]. In our proposed work PN-sequence generator will be called as Pseudorandom binary sequence (PRBS) random bits[2].

The selection of the triangular waveforms will be done according to the sequence generator bits i.e. “0” for low and “1” for high. PN-Sequence table for selection is shown in TABLE I.

2014 Fourth International Conference on Communication Systems and Network Technologies

978-1-4799-3070-8/14 $31.00 © 2014 IEEE

DOI 10.1109/CSNT.2014.199

970

2014 Fourth International Conference on Communication Systems and Network Technologies

978-1-4799-3070-8/14 $31.00 © 2014 IEEE

DOI 10.1109/CSNT.2014.199

970

TABLE I Logic Table for PN-Sequence Gen

PN–Sequence

Generator(PRBS)

Output (X)

0

��

1

Q

III. PROPOSED PSEUDORANDOM

In the above proposed pseudorandom carare two triangular waveforms “Q” and “�� equal frequency which are opposite in phas

generator is randomly generating bits and thto the multipliers.

A not gate is used to invert the PN-sequemultiplied by the out of phase “�� ” wave .Fis being used to add up the results of Resultant will be a “X” wave which called aCarrier Frequency.

Fig.1. Principle of the proposed scheme.

Fig.2. Pseudorandom Waveform generation

nerator

SCHEME

rrier scheme there ” with fixed and

ses. PN-sequence

hey have been fed

ence so as to be Finally a summer

multipliers and as Pseudorandom

In fig.2. We can justify the abovegeneration of Pseudorandom CarrieIn the above simulation work “Q”=5Khz with a 12bit sequence gresultant switching pulses which ha

constant DC reference signal of 1.5vFor verification of the proposed sch(Chopper) is being implemented and

IV. BOOST CON

General application of boost converthe field of DC-power supplies andDC motors. As “Boost” implies involtage is always greater than input on, the diode is reversed biased andThe inductor is supplied with energsupply, when switch is off; the outppackets from both inductor and inpuoperation is demonstrated to explain Chopper Operation:

The chopper is a semiconduwhich provides a keen reland output parameters at fasat times when the switcdisconnected from the loadload will be connected to theAverage voltage [12],

���� � ��

�� � � �

�� � ���

� � ���

Uncontrolled parameters: • �� �Source Voltage.

Fig.3. Resultant Switching Puls

n.

e conclusion made for the er Frequency Waveform. proposed scheme have enerator.Fig.3. shows the

as been compared from a

volt . heme a DC-DC converter d results are analyzed.

NVERTER

rter (step up) is related to d regenerative braking of n this regard as “Output voltage”. When switch is

d hence output is isolated. gy packets from the input put stage receives energy ut supply. Simple chopper n the above statement

uctor device (switch=SW) lationship between input st switching rate therefore ch is on the input is d ,when switch is off the e input.

������ (1)

��� ��� (2)

�� (3)

� (4)

ses.

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Controlled parameters:

• � � Duty ratio. • � �� � ���=Chopping perio• �� � ON period. • ��� �OFF period. • � �

�=Chopping Frequency. Step up (boost) switching converters transfof energy using similar devices as menconverters but with slight changes arrangements.

• Average output voltage of Boterms of duty ratio: �� � �����

V. MATHEMATICAL MODELLING OF BOO

State-space modeling represents true dcircuit. Considering fig.5. Let’s assume pboost converter in open switch condition (switch condition (S=1).

�� �Input Variable. �� �Output Variable. Applying Kirchhoff’s voltage law assumingon the converter we arrive to a mathematicspace [7].

���� � ������

����� � �! " ��#!

Fig.4. Resistive load Chopper circuit and w[8], [10].

Fig.5. Boost converter.

od.

fers large packets ntioned for buck

in the circuit

oost converter in

(5)

OST CONVERTER

dynamics of the parameters for a (S=0) and closed

g switching (S=1) cal model in state

(6)

(7)

Final state space model of boost con

$ %&'(&) � * + "���,�- "

By replacing S=0 and S=1 we cequations for modeling boost conveof switch(S).

VI. EXPERIMENT

A setup is made in MATLAB to progeneration of pseudorandom carriePseudorandom switching pluses artherefore rest of the switching pufrequency system of 5KHz and Pulsthe fig.9. and fig.10.As a results

arrangements we can look after voltage of boost converter and its co

waveform

Fig.6. Pseudorandom Carrier bfed to a Boost converter.

Fig.8. Pulse Generator SwitBoost converter.

Fig.7. FIXED frequency 5pulses fed to a Boost converter

nverter:

���,�." �/-0 $ %'() � 123.+4 (8)

can determine the State erter in OFF and ON state

TAL SETUP

ovide an environment for er. As mentioned earlier re shown in the fig no.3 ulses generated by Fixed se generator are shown in

after understanding the

for the resulting output omponents assembled .

based Switching pulses

tching pulses fed to a

Khz based Switching r.

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VII. POWER CONVERTER OUPUT LEVELS

After generating the switching pluses for the Boost converter using different conventional schemes and from the proposed Pseudorandom method. The boost converter output is analyzed on the basis of the switching losses across the Semiconductor switching device(IGBT), inductor current, diode current and load voltage. In the conventional schemes of fixed frequency 5khz system reference level is fixed up to 1.5 volt same as in case of proposed work.

Special case arises when the there is a change in the reference signal level. In pseudorandom scheme we observe

that the output level boosts to a larger value whereas in fixed frequency scheme the output level falls rapidly.

Now as per the previous statements, we assumed a reference signal level of 4.5volts for the proposed pseudorandom scheme. A remarkable gain in the output voltage is obtained for same input voltage shown in fig.14.

Similarly, from previous assumptions as were assumed in the pseudorandom scheme were taken as reference for a distinct comparison between the boost converter output levels for a fixed frequency carrier scheme and pseudorandom scheme. As shown in fig. 15. There is a decrease in output level in fixed frequency scheme for same input voltage and 4.5 volts

of reference signal.

Fig.14. Boosted Output results of Boost converter using Pseudorandom Carrier modulation scheme with reference signal of 4.5V.

Fig.11. Output results of Boost converter using Pulse Generator.

Fig.12. Output results of Boost converter using Fixed frequency 5khz system.

Fig.13. Output results of Boost converter using Pseudorandom Carrier modulation scheme.

Fig.9. Pulse generator switching pulses

Fig.10. FIXED frequency 5Khz based switching pulses

Fig.15. Degraded Output results of Boost converter using fixed frequency modulation scheme with reference signal of 4.5V.

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VIII. CONCLUSION

FFT analysis tool based in the MATLAB simulation environment is worked on to meet our purpose to analyze the load voltage harmonics occurring in all the three schemes as are:

• Load voltage analysis using pulse generator. • Load voltage analysis using fixed frequency

carrier. • Load voltage analysis using Pseudorandom

Carrier Frequency. Pseudorandom carrier scheme has proven to be an

optimized scheme as for the merits: 1. Inductor current is reduced 2. IGBT switching losses are reduced. 3. Output can be increased by varying DC-reference.

ACKNOWLEDGMENT

The research work proposed being dealt under the Electrical Engineering Department at DIT, university, Dehradun, INDIA. For an inspirational approach towards

research in the field of Power Electronics and Drives for a motivational grade in Master of technology.

REFERENCES

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Industrial electronics, Vol. 39,no.5,December 1992.

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[3] Michael M.Bech, Frede Blaabjerg and John K.Pedersen, “Random Modulation Techniques with Fixed Switching Frequency for Three-Phase Power Converters”, IEEE Trans, Power Electronics ,Vol. 15,no.4, July 2000.

[4] R. Krishnan, Electric Motor Drives- Modeling, Analysis and Control, 10th edn.,Prentice Hall, Upper Saddle River, NJ, 2001.

[5] Alan Martin, “Boost Converter Design Tips, in Field Applications Engineering”, National semiconductors, March 2005.

[6] Young –cheol Lin, Young-gook jung, jong-nam kim and seog-oh wi , “A pseudorandom carrier modulation Scheme ”, IEEE Trans, vol 25, no.4,April 2010.

[7] Magnus Hedlund, “Design and Construction of Bidirectional DC-DC Converter for an EV Application”, (http://www.teknat.uu.se/student, Feb, 2010).

[8] Muhammad H. Rashid, Power Electronics- Ciruits, Devices, and Applications, 9th edn.,Springer-Verlag, New York, 2011.

[9] V. Jayamala, S. Ramasamy, and S. Jeevananthan, “Investigation of Pseudorandom Carrier Pulse Width Modulation Technique for Induction Motor Drives”, International conference on current trends in technology, December 2011.

[10] Naveen R. Sharma, Ravishankar Kumar and N.G.Mishra, “Simulation of Four quadrant Chopper using PSIM”, in World Journal of Science and technology . 2(4) ,2012,page no. 70–74.

[11] S.S. Raghuwanshi, K. Gupta, S.Manjrekar, D. Choudhary, Y.Mokhariwale, “Analysis and Design of a Closed-Loop Converter Controlled DC drive”, in International Journal of Engineering Trends and Technology. Volume-3, Issue-3 , 2012.

[12] Anant Kumar Verma,Gagan singh, “Performance Study of Power Control Method for Chopper Fed Separately Excited DC (Direct Current)-Drive using PSIM”, world Conference on Advances in Communication and Control Systems ,2013

Pulse generator scheme

Fixed frequency scheme (5Khz)

Pseudorandom Carrier Frequency scheme

Fig.16. FFT analysis of the schemes under study.

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