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A Novel Hysteresis Current Control Scheme forSingle Switch Type Single Phase PFC ConverterAtsushi Hirota*, Satoshi Nagai**, Mamun Abdu llah AI***, M. Rukonuzzaman***, and Mutsuo Nakaoka***

Department of Electrical and Computer Engineering, Akashi National College of Technology*679-3 Nishioka, Uozumi-Cho, Akashi-City, Hyogo-Pref., 674-8501 JapanPhone ;+81-78-946-6128, Fax :+81-78-946-6138E-Mail :ahirota@akashi.ac.jpDepartment of Electrical Engineering, T suyam a National College of Technology, Japan**Department of Electrical and Electronic Engineering, Yamaguchi University, Japan***

AbstractWith great advance of power sem iconductor sw itching

devices and th eir related control circuits, high frequen cyswitching powe r converters can be implem ented o r powerelectronic appliances. In these converters, pulse widthmodulation (PW M) echnique is widely used.

On the other hand, to improve powe r fac tor in utility ACside of converter; a variety ofpow erfactor correction (P FC )converters are effectively introduced. For these converters,hysteresis current control method is developed andapplying. Usually, this control scheme uses referencesinusoidal wave and up per limit signal which is determinedby added consta nt value to reference signal, as well as lo werlimit signal which is determined by subtracted co nstantvalue fro m the reference signal. U sing these signals,hysteresis current control method for PFC converterregulates its input current within the range that isdetermined by the upper and low er limit.

In this paper; the a uthorspropose a simple configurationhysteresis controlled PFC converter which can effectivelyreduce current ratings of switching power device. Theproposed PFC conver ter controls input line current keepswithin the constant upper lim it, specijied by the switchingpowe r semicond uctor device rating, as well as lower limitdetermined by reference sinusoidal wave. From FFTanalytical results, the proposed circuit can lower thecurrent rating of switching powe r device than undamen talcomponen t of input line current.Ke y words: PFC converter , hysteresis control, currentlimiting scheme1 INTRODUCTION

ComparatorIUFig. 1. Proposed PF C converter circuit.correction (PFC) converters are generally used, whichactively adju sts input current waveform to sin usoidal. Inthese PFC converters, hysteresis controller which controlsinput current within the specified range between upper andlower sinusoidal limit, are abl e to be effectively introduced.

In this paper, the authors propose a novel PF C convertercontrol schem e that can reduce current ratings of switchingpower semiconductor device. In proposed input currentcontrol scheme, the upper limit is changed to the constantva lue . From the s imula t ion resu l ts , peak cur ren t ofswitching devices could be decreased. And it is confirmed,by using proposed PFC converter, that the fundamentalcomp onent of the input current can be larger than the ratingof switching device.2 Proposed Circuit and Control Method

With the progress of power semiconductor switchingdevices manufacturing technologies, high frequency pow erconverters have been making progress so fa r [ l ] , [2 ] .Recently, PFC converters, that instantaneously control inputline current as sinusoidal wave, are proposed. Above all,o improv e power factor of utility AC side, pow er factor

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Current4 UmerLimit

Table 2.Analytical conditions.Symbol I Condition

Fig. 2. Hysteresis limiter control.

Table 1. List of symbols.Svmboll Defined terminology

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Reference input signal voltage(rms)Reference input signal frequencyReference signal current(rms)(%)Maximum switch current limit compared tomaximum reference signal current(%)Lower switch current limitAmplitude of fundamental component(rms)Total harmonic distortionSwitching numberInstantaneous line input currentInstantaneous source voltage

hysteresis current control method is adopted usefully.This paper is presented how to reduce current rating of

switching power device. The proposed con verter circuitalter the control method of conventiona l hysteresis control.The upper limit of the input current takes a constant valueof the switching power device rating while lower limit ofthe input current is sinusoidal wave that is subtracted aconstant value from the reference signal.

Fig. 1 shows the proposed PFC converter circuit. Afterfull wave rectifying the input AC sou rce, the boost typePFC converter circuit is introduced. Input side low passfilter configurated by and C , are not considered in thisanalysis for simplicity. As a reference signal, full waverectified AC source v oltage is used.

The input line current is controlled within the range ofupper limit and lower limit as shown in Fig. 2.

The upper limit is set to a constant value specified by

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0 2 4 6 8 IO 12 14 16x10~'rime [reelFig. 3. Simulated input current waveforms.

switching power device rating and the lower l imit isdetermined by subtracting a constant value from thereference sinusoidal wave. For exam ple, when input currentin utility AC side decreases to a lower limit, the switch isset on state and input current increases. Then, the inputcurrent reaches to upper limit and the switch is set to be offstate so as to decrease input current. The decreasing speedof the input curren t is faster when converter load is heavy.Continuous operation of these control schemes, the peakinput line current can be controlled under current rating ofswitching power device.

Table 1 ndicates sym bols used in this paper.3 Simulation Results and Their Discussions

Table 2 shows analytical conditions considered in thispaper. In this case the rating of the sw itching device is setto 17(A).

Fig. 3 depicts the input line current waveform of theproposed PFC converter. The input l i e current is controlledwithin the range between a constant upper l imit andsinusoidal lower limit.

Fig. 4 represents the spectrum distribution of the inputline current as shown in Fig. 3. The vertical axis takes

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Fig. 4. Simulated input current spectrum distribution ofproposed PFC converter.

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Table 3. FFTanalytical results.i,,JA) I THD(%) I N ,17.8 I 36.3 I 45 8

logarithm. This figure shows that harmonic com ponentsare relatively small. And from Fig. 5 , the fluctuation ofoutput is small. Fig. 6 represents switch current. From thisfigure, switch current is suppressed under the rating ofswitching device.

Table 3 shows FFT analytical result of the proposedcircuit. This table indicates that the fundam ental amplitudeof the input line current is 17.8(A) and this value is largerthan the rating of switching dev ice set in Table 2.

From these results, the proposed PFC converter canreduce current rating of sw itching power device . In additionto this, the proposed PFC converter can take simpleconfiguration.4 Conclusions

In this paper, a simple one switch type single phase PFCconverter with a hysteresis current controller, which canbe configured by simple control strategy, was proposed an danalyzed on the basis of computer simulation.

To r e d u c e p e a k c u r r e n t of s w i t c h i n g p o w e rsemiconductor device, maximum cu rrent value is controlledto a constant value. As a result , using proposed PFCconverter, it is confirmed that the fundam ental compon entof the input line current can take large r value than the ratingvalue of the switching power device.This means that usinga same switching device, the proposed PFC converter cantreat larger power than con ventional PFC converter.

I I I I I I0 2 4 6 8 IO I2 14 16x1U3

limc [se=]

Fig. 6. Simulated switch current waveforms.

References[l] D.M.Divan, Resonant DC-link Converter -A New

Concept in Static Power Conversion, IEEE-IASConference Proceedings 1986, pp.267-280, 1986.

[2] A.Cheriti et al., A Rugged Soft Commutated PWMInverter for AC Drives, IEEE PESC90, ConferenceRecords 1990, pp.656-662, 1990.

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