ISSN Vol.04,Issue.15, October-2016, Pages:

Transcription

1 ISSN Vol.04,Issue.15, October-2016, Pages: Power Factor Correction AC-DC Power Converter with One Switching Per Cycle for High Frequency Input JATAVATH RAKESH 1, ANUGU RAM REDDY 2, S. RAJESH 3 1 PG Scholar, Dept of EEE, Siddhartha Institute of Engineering and Technology, Ibrahimpatnam, Hyderabad, Telangana, India. 2 Assistant Professor, Dept of EEE, Siddhartha Institute of Engineering and Technology Hyderabad, Telangana, India. 2 Assocoaite Professor & HOD, Dept of EEE, Siddhartha Institute of Engineering and Technology Hyderabad, Telangana, India. Abstract: This paper presents a power converter and its control circuit for high-frequency-fed ac to dc conversion. The energy efficiency and power transfer capability of a poor PF system are relatively low because of the high conduction loss in the power converters and transmission wires. Additionally, the distorted current has a rich high-order harmonic content which may cause the emission of electromagnetic interference (EMI) that affects the operation of neighbor electronic equipment. A power electronic converter such as a boost converter can be used to shape the input ac current drawn by the rectifier to be sinusoidal and in phase with the ac voltage. A classical boost converter connected after a diode bridge rectifier to form a PF correction (PFC) circuit. The output dc voltage is sensed and fed to an error amplifier. The difference between the actual and reference voltage is derived and applied to a compensator circuit such as a proportional-integral (PI) compensator. The output of the compensator is multiplied with the signal proportional to the ac voltage waveform vs. to produce the reference current signal il, ref. Afterward, a current-mode controller is used to generate the ON and OFF signal to the switch shaping the current waveform of the inductor. Therefore, the average wave shape of the ac current is forced to follow the waveform of the ac voltage. It can be observed that the switching frequency of the PFC converter must be several time higher than the frequency of the ac system.. Keywords: High-Frequency-Fed Unity Power Factor Ac-Dc Power Converter with One Switching Per Cycle. I. INTRODUCTION The energy efficiency and power transfer capability of a poor PF system are relatively low because of the high conduction loss in the power converters and transmission wires. Additionally, the distorted current has a rich high-order harmonic content which may cause the emission of electromagnetic interference (EMI) that affects the operation of neighbour electronic equipment. A power electronic Converter such as a boost converter can be used to shape the input ac current drawn by the rectifier to be sinusoidal and in phase with the ac voltage. A classical boost converter connected after a diode bridge rectifier to form a PF Correction (PFC) circuit. The output dc voltage is sensed and fed to an error amplifier. The difference between the actual and reference voltage is derived and applied to a compensator circuit such as a proportional-integral (PI) compensator. The output of the compensator is multiplied with the signal proportional to the ac voltage waveform vs. to produce the reference current signal il, ref. Afterward, a current-mode controller is used to generate the ON and OFF signal to the switch shaping the current waveform of the inductor. Therefore, the average wave shape of the ac current is forced to follow the waveform of the ac voltage. It can be observed that the switching frequency of the PFC converter must be several time higher than the frequency of the ac system. II. MODULE DESCRIPTION Ac Dc Conversion: Usually the ac to dc conversion is a rectifier. The rectifier converts alternating current into direct current. It contains four diodes. There is some drawbacks in the half wave and full wave rectifier. In half wave rectifier the ripples are high and in full wave centre tapped transformer is the problem. These problems can be overcome by bridge rectifier. In bridge rectifier can achieve the efficiency 81.2.during positive half of the supply the diode D1 and D3 conducts. So the current flow through source.diode 1,load,diode 3 and returned back to the source. During negative half of the supply the diode D2 and D4 conducts. So the current flow through phase, diode 2, load, diode 4 and neutral cause the emission of electromagnetic interference (EMI) that affects the operation of neighbor electronic equipment. A power electronic converter such as a boost converter can be used to shape the input ac current drawn by the rectifier to be sinusoidal and in phase with the ac voltage [11]. Fig. 2(a) shows a classical boost converter connected after a diode bridge rectifier to form a PF correction (PFC) circuit. The output dc voltage is sensed and fed to an error amplifier. The difference between the actual and reference voltage is derived and applied to a compensator circuit such as a proportionalintegral (PI) compensator. The output of the compensator is multiplied with the signal proportional to the ac voltage waveform vs to produce the reference current signal il,ref. Afterward, a current-mode controller is used to generate the ON and OFF signal to the switch shaping the current waveform of the inductor IJIT. All rights reserved.

2 JATAVATH RAKESH, ANUGU RAM REDDY, S. RAJESH substantially reduce the structural parasitic and to improve the thermal management. However, the thermal performance and EMI are still big challenges which are difficult to solve individually as they are closely related to the circuit layout and packaging [20]. Fig.2.(a) PF correction circuit. (b) Input voltage and current waveforms. Fig.1. (a) Diode rectifier with a capacitor connected at the dc output side. (b) Input voltage and current waveforms. Therefore, the average waveshape of the ac current is forced to follow the waveform of the ac voltage. Fig. 2(b) depicts the input ac current waveform of the converter. It can be observed that the switching frequency of the PFC converter must be several times higher than the frequency of the ac system. Using a 400-kHz ac transmission system as an example, applying this current shaping technology implies that the power switch has to operate in the tens of MHz. As a result, the switching loss becomes significant and the efficiency of the converter sharply reduces. Furthermore, MHz switching converter is also exposed to a number of problems arising from the passive and active components. For instance, the loss associated with the charging and discharging of the parasitic capacitance of power MOSFETs becomes significant [12], [13]. The high-frequency behavior of the devices is very different from that of the low-frequency behavior [14], [15]. In terms of using passive components in design, it is important to enhance their temperature stability and to minimize the unwanted stray and parasitic elements [15]. For the design of printed circuit board, it is crucial to eliminate undesired coupling between neighboring components and the rest of the circuit [16]. Without addressing these issues, the converter cannot be operated at a high frequency and achieved a high Efficiency[17]. In[18] and [19], device-level packaging and circuit interconnection technologies are proposed to The paper is organized as follows. In Section II, the concept of using inductor capacitor (LC) series resonant circuit to perform PF correction will be introduced. The operating principle of the proposed high-frequency-fed ac dc power converter will be explicitly described using the corresponding timing diagrams and equivalent circuit diagrams. Then, the voltage conversion ratio and efficiency of the converter will be analytically investigated and presented in Section III. Afterwards, the construction of a proof-of-concept prototype and its experimental measurement results will be discussed. Section V gives the conclusions of the paper. II. RESONANT INDUCTIVE COUPLING Inductive or magnetic coupling is based on the principle of electromagnetism. When a conductor is proximity to a magnetic field, it induces a magnetic field in that wire. Transferring energy between wires through magnetic fields is inductive coupling. Magnetic resonant coupling uses the same principles as inductive coupling, but it uses resonance to increase the range at which the energy transfer can efficiently take place[4], [5]. Resonant inductive coupling is the near field wireless transmission of electrical energy between two coils that are tuned to resonate at the same frequency and is depicted in Fig. 1. Resonant transfer works by making a coil ring with an oscillating current. This generates an oscillating magnetic field. Because the coil is highly resonant, any energy placed in the coil dies away relatively slowly over very many cycles; but if a second coil is brought near it, the coil can pick up most of the energy before it is lost, even if it is some distance away. The oscillations in the magnetic field will die away at a rate determined by the gain-bandwidth (Q factor) due to resistive and radiative losses.

3 Power Factor Correction AC-DC Power Converter with One Switching Per Cycle for High Frequency Input Because the Q can be very high, even when low power is Lr1Cr1 and Lr2Cr2 respectively during the PFC stage. fed into the transmitter coil, a relatively intense field builds up Meanwhile the switches S3 and S4 are used to control the over multiple cycles, which increases the power that can be Buck-Boost converter in regulation switch during the positive received. Thus, at resonance far more power can be and negative half cycles respectively. MODE 1: We assume transferred wireless. Resonant circuit can be either series or capacitors Cr1 and Cr2 are initially charged to Vcr,min and parallel. The difference is how they are connected to the Vcr,max respectively. In the first stage, ie., PF correction power amplifier of the system. A parallel resonator is used in stage, S1 is turned ON and S2 remains OFF. D1 and D4 are the parallel case, and in the series case a series resonator is forward biased and diodes D2 and D3 are reverse biased. Lr1 used. The two types of circuits behave similarly but some and Cr1 together forms a series resonant circuit. The inductor differences exist, ie., to drive a parallel circuit the driving current starts from an initial value, say zero, follows the circuit should have a high output resistance, and therefore sinusoidal waveform and decreases to zero as D1 and D4 are behave like a current source rather than a voltage source to reverse biased. The voltage across the capacitor Cr1 is minimize the reduction of the resonator quality factor. For the charged from initial value Vcr,min to a certain level. Mode 1 series circuit the opposite is true, the driving circuit should is illustrated in Fig. 3. have a low output resistance. In addition to transferring the power efficiently, the transferred voltage should not vary too much. Keeping the voltage stable even with variations in the coupling coefficient is desirable to reduce the power loss in the voltage regulator, as well as preventing the load circuit from being damaged from high voltage III. RECIEVER TOPOLOGY The proposed two stage topology is shown in Fig. 2[1]. The two stages are PFC (Power Factor Correction) and regulation stage respectively. The PFC stage consists of two switches, four diodes, two resonant inductors and two resonant capacitors. The regulation stage comprises of two switches, three diodes, one capacitor and one inductor The entire process can be summarised as, in the first stage, ie., in the PFC stage, capacitors Cr1 and Cr2 are alternatively charged by input AC voltage source by alternative switching of switches S1 and S2 respectively. In the second stage ie., in the regulation stage the previously charged capacitors commutates alternately as energy sources for second stage. Buck-Boost converter is used for regulation stage and in total there are four modes of operation for the proposed topology Fig. 3: Mode 1 In the second stage, ie., regulation stage, S4 is turned ON while S3 in OFF state. Diode D6 is forward biased while diodes D5 and D7 reverse biased. Cr2 is discharged in one direction because of polarity of diode D6. Energy from the PFC stage get transferred to the regulation stage and is stored in the inductor L. The energy to the output load resistor RL is delivered by output capacitor CO. MODE 2: The PFC stage does not get altered in the Mode 2 operation and is shown in Fig. 4. Switches S1, S2 and diodes D1, D2, D3, D4 have similar functions as that of Mode 1. Capacitor Cr1 charges to Vcr,max as positive half cycle ends. Switch S1 gets commutated naturally Fig.4. Mode 2. Fig2. Overall control block diagram, of high frequency fed AC-DC power Converter. A. Modes of Operation As previously stated there are four modes of operation. The switches S1 and S2 are used to select the resonant tanks Diodes D1 and D4 gets reverse biased, while S3 and D5 in the regulation stage remains OFF. The current of inductor L results in the forward conduction of diode D7. And in this stage energy stored in the inductor is delivered to the output capacitor CO and load resistor RL. MODE 3: In the PFC stage, ie., in negative half cycle, switch S2 is turned ON and switch S1 is turned OFF. Diodes D2 and D3 are forward biased and diodes D1 and D4 are reverse biased. Capacitor Cr2 charges from Vcr,min to Vcr,max. Mode 3 is shown in Fig. 5.

4 JATAVATH RAKESH, ANUGU RAM REDDY, S. RAJESH captured and is shown as Fig. 10. The power factor correction, ie., input current and voltage is depicted in Fig. 11. The simulation waveforms are in good agreement with the theoretical analysis Fig5. Mode 3. Whereas in regulation stage, switch S3 turns ON and switch S4 and diode D6 remains in OFF state. Diode D5 forward biased and diode D7 reverse biased. Cr1 discharges to inductor L until the voltage of capacitor Cr1 is equal to Vcr,min. At the same time load resistor RL is supplied by the output capacitor CO. MODE 4: Mode 4 is illustrated in Fig. 6. In the PFC stage, switches S1 and S2 and diodes D1 and D2 have same switching states as that of previous mode. Energy stored in inductor L during previous mode is discharged to CO and RL through diode D7. Switch S2 is commutated at the end of negative half cycle and later the entire modes are repeated. Fig7. Simulation Design of Proposed System Fig8. Control System of Proposed System Fig.6. Mode 4. B. Control Methodology A control methodology based on analog circuits is implemented. A phase detector circuit is used in the PFC stage to control the ON/OFF time of switches S1 and S2. The AC source voltage Vin is sensed and given to the phase detector circuit where the output of phase detector circuit is connected to the driver circuit of switches S1 and S2. The control signals for the switches S3 and S4 are derived from the pulse width modulation generators in which output from the phase detector circuit are applied. ie., in the regulation stage, the instantaneous voltage of resonant capacitors are sensed and compared with Vcr,min to generate the pulses of switches S3 and S4. IV. SIMULATION RESULTS The proposed high frequency fed AC-DC power converter and its control circuit is implemented using OrCAD. Fig. 7 shows the pspice model of the proposed converter. The converter is designed such as to convert a 400 khz AC voltage source into a DC source. The input voltage provided to the converter is 50 Vrms.The output power obtained is 30 W. The output voltage obtained is 54 V and is shown in Fig. 8. The input-output voltage waveforms are captured and are shown in Fig. 9. Also the voltage across resonant capacitors is Fig.9. Output voltage. Fig.10. Voltage across resonant capacitors.

5 Power Factor Correction AC-DC Power Converter with One Switching Per Cycle for High Frequency Input Fig.11. Input voltage and current. TableI. Circuit Specifications Fig.13. Switching pulses to S1 and S2. The circuit specifications are summarised in Table I. And the block diagram of entire wireless power transfer system is depicted in Fig. 12. AC is converted to High frequency AC with the help of a controller and is fed to the transmitter. The receiver is in vicinity of transmitter magnetic field and is rectified to feed the load. The component specification used for simulation in OrCAD is summarised in Table II. The switching pulses to switches S1 and S2 are shown in Fig. 13 whereas pulses to switches S3 and S4 are depicted in Fig. 14. Table II. Component Specifications Fig12. Block diagram of hardware development. Fig.14. Switching pulses to S3 and S4. V. CONCLUSION A 400-kHz high-frequency-fed ac dc PFC converter with one switching action per cycle is demonstrated. With a single converter topology, the converter is able to perform the function of a buck and boost conversion depending on the characteristic impedance of the resonant tank. The voltage conversion ratio of the converter can be further controlled by the initial voltage of the resonant capacitors. A control scheme is also proposed for the converter. It can be realized by simple operational amplifiers and digital logic gates, and thereby can be easily fabricated as an IC for mass production. The distinctive features of this converter are favorable for future high-frequency ac power transfer system operating in the range from a few hundred khz to the MHz range. Future scope: In the paper we proposed the self Repairing for MAT Lab only in Future we can High Frequency Fed Unity Power Factor Ac Dc Power Converter with One Switching per A power converter and its control circuit for highfrequency-fed ac to dc conversion. It will be implemented for high power application in future. According to literature survey, since all the switches are operated at the fundamental frequency of the input ac source, the switching loss of the converter is small. VI. REFERENCES [1] N. Tesla, Apparatus for transmitting electrical energy, U.S. Patent , Dec. 1, [2] J. Schuder, H. Stephenson, and J. Townsend, High-level electromagnetic energy transfer through a closed chest wall, Inst. Radio Engrs. Int. Conv. Rec., vol. 9, pp , [3] J. C. Schuder, J. H. Gold, and H. E. Stephenson, An inductively coupled RF system for the transmission of 1 kwof

6 power through the skin, IEEE Trans. Biomed. Eng., vol. BME-18, no. 4, pp , Jul [4] W.Ko, S. Liang, and C. F. Fung, Design of radiofrequency powered coils for implant instruments, Med. Biol. Eng. Comput., vol. 15, pp , [5] M. Kiani and M. Ghovanloo, The circuit theory behind coupled-mode magnetic resonance-basedwireless power transmission, IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 59, no. 8, pp. 1 10, Sep [6] S. Cheon, Y. H. Kim, S. Y. Kang, M. L. Lee, J. M. Lee, and T. Zyung, Circuit-model-based analysis of a wireless energy-transfer system via coupled magnetic resonances, IEEE Trans. Ind. Electron., vol. 58, no. 7,pp , Jul [7] Y. H. Kim, S. Y. Kang, S. Cheon, M. L. Lee, J. M Lee, and T. Zyung, Optimization ofwireless power transmission through resonant coupling, in Proc. Compat. Power Electron., 2009, pp [8] N. Y. Kim, K. Y. Kim, J. Choi, and C. W. Kim, Adaptive frequency with power-level tracking system for efficient magentic resonance wireless power transfer, Electron. Lett., vol. 48, no. 8, pp , Apr [9] S. Y. R. Hui, D. Lin, C. K. Lee, and J. Yin, Methods for parameters identification, load monitoring and output power control for wireless power transfer, U.S. Patent Application, US 61/862,627, Aug. 6, [10] N. Mohan, T. M. Undeland, and W. P. Robbins, Power Electronics: Converters, Applications, and Design, 3rd ed., New York, NY, USA: Wiley, 2000, pp [11] C. K. Tse, Circuit theory and design of power factor correction power supplies, IEEE Distinguished Lecture 2005, Circuit and Systems. [Online]. Available: [12] K. Gauen, The effect of MOSFET output capacitance in high frequency applications, in Proc. Ind. Appl. Soc. Annu. Meet., 1989, vol. 2, pp [13] M. Hartmann, H. Ertl, and J.W. Kolar, On the tradeoff between input current quality and efficiency of high switching frequency PWM rectifiers, IEEE Trans. Power Electron., vol. 27, no. 7, pp , Jul [14] Z. Chen, D. Boroyevich, and J. Li, Behavioral comparison of Si and SiC npower MOSFETs for highfrequency applications, in Proc. Appl. Power Electron. Conf. Expo., 2013, pp [15] Q. Li, M. Lim, J. Sun, A. Ball, Y. Ying, F. C. Lee, and K. D. T. Ngo, Technology roadmap for high frequency integrated dc dc converter, in Proc. Power Electron. Motion Control Conf., 2009, pp [16] W. Liang, J. Glaser, and J. Rivas, MHz high density DC DC converter with PCB inductors, in Proc. Appl. Power Electron. Conf. Expo., 2013, pp [17] J. M. Burkhart, R. Korsunsky, and D. J. Perreault, Design methodology for a very high frequency resonant boost converter, IEEE Trans. Power Electron., vol. 28, no. 4, pp , Apr [18] S. Ji, D. Reusch, and F. C. Lee, High-frequency high power density 3-D integrated gallium-nitride-based point of JATAVATH RAKESH, ANUGU RAM REDDY, S. RAJESH load module design, IEEE Trans. Power Electron., vol. 28, no. 9, pp , Sep [19] F. C. Lee and J. D. vanwyk, IPEM-based power electronics system, in Proc. Integr. Power Syst., 2006, pp [20] W. Zhang, F. C. Lee, and D. Y. Chen, Integrated EMI/Thermal design for switching power supplies, in Proc. IEEE 31st Annu. Power Electron. Spec. Conf., Jun , 2000, vol. 1, pp [21] C. K. Lee and K. Sitthisak, Electronic apparatus and control method for high frequency AC to DC conversion, U.S. Patent Application, US 14/160,830, Jan. 22, Author s Profile: Jatavath Rakesh is currently pursuing M.Tech with specialization in Power Electronics at Siddhartha Institute of Engineering & Technology, Telangana, India. He has received her bachelor degree in Electrical & Electronics Engineering from Progressive Engineering College(PEC), Nalgonda, Telangana, India. Anugu Ram Reddy has been awarded his M.Tech. in Electrical Power System( EPS) from Jawaharlal Nehru Technological University Anantapur, (JNTUA), Anantapur, Andhra Pradesh India (2009) and B.Tech. in Electrical & Electronics Engineering from Khader Memorial College of Engineering & Technology, Nalgonda, India (2006). Presently, he is Professor in the department of EEE, Sidhartha Institute of Engineering and Technology, Ibrahimpatnam, Hyderabad, Telangana, India. S. RAJESH received M.Tech degree in Power Electronics from Jawaharlal Nehru Technological University Hyderabad, Telangana, India in 2010 respectively. He has presented nearly 5 papers in National level conferences. His research interests are power electronics applications in distributed power generation and analysis of power converters, control and estimation in induction motor drive and wind turbine driven induction generator. Currently he is working on stability studies of Double Fed Induction Generator in Wind power Generation. He is a Student member of IEEE and life Member of ISTE (India). He currently serving as Associate Professor & Head of the Department of Electrical and Electronics engineering in Siddhartha Institute of Engineering & Technology Hyderabad, Telangana, India. He has 8 years experience in teaching.