Student Department of EEE (M.E-PED), 2 Assitant Professor of EEE Selvam College of Technology Namakkal, India

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1 Design and Development of Single Phase Bridgeless Three Stage Interleaved Boost Converter with Fuzzy Logic Control System M.Pradeep kumar 1, M.Ramesh kannan 2 1 Student Department of EEE (M.E-PED), 2 Assitant Professor of EEE Selvam College of Technology Namakkal, India Abstract This paper presents a two phase interleaved power factor correction boost converter with a variation tolerant phase shifter (VTPS), which ensures accurate 180 phase shift between the two interleaved converters. The input current ripple and current stress increases the conduction losses and reduces the lifetime of the input source with a bridge circuit. The proposed system eliminates this problem and results in decreased conduction loss increasing the life time of the input source by bridgeless circuit with the fuzzy logic control system. The proposed system results with higher efficiency, good power factor, reduction in size, reduced ripples to operate at the high power applications. A single-phase bridgeless three stage interleaved power factor correction boost converter prototype has been implemented. The results are validated through MATLAB/Simulin keywords Interleaved Boost Converter (IBC); power factor correction (PFC); Fuzzy Logic Control System (FLCS). I. INTRODUCTION Power factor (PF) defined as the ratio of real power to apparent power is desired to be 100% because the smaller PF, the larger power loss and harmonics, which may travel down the power line and disrupt other devices connected to the line [1]. For a higher PF, a power factor correction (PFC) circuit is employed which shapes the input current waveform to be in phase with the input voltage waveform [2]. PFC circuits can be classified as either passive or active PFC among which active PFC is preferred due to its small form factor and higher PF [3]. The operation modes of an active PFC converter can be classified as the continuous conduction mode (CCM), discontinuous conduction mode (DCM), or critical conduction mode (CRM) depending on the current flowing through the inductor [4]. For a heavy load, the CCM is usually employed because it can handle more current than the DCM and CRM [5]. At the CCM, however, the hard switching of the freewheeling diode may result in decreased power conversion efficiency [6]. On the contrary, the freewheeling diode is switched softly at the DCM and CRM and thus higher power efficiency can be expected [7]. The DC-DC boost converter is generally used to boost the voltage to the required level [8]. In earlier the conventional boost converters are used to boost up the voltage to the required level based upon the application [9]. To minimize the ripples, using the interleaved concept an Interleaved Boost Converter (IBC) has been proposed [10]. Due to a phase shift of 180 degrees, the ripple cancellation takes place [11]. The fuzzy logic controller is composed with the Interleaved Boost Converters (IBC) to obtain the high gain of switched capacitors and coupled inductors [12]. The proposed system can be used in industry and high power applications, the system efficiency is increased. Simulation results show that the current ripple in the input and output circuits is less and also minimizes the size of input filter and output power is more for IBC. This project concentrates on the various design aspects, steady state and transient response, device selection, operating principle, gating pattern and the various waveforms which compares with the conventional boost converter. The main objective of this project is to clearly study about the conventional boost converters, interleaved techniques and its implementation. The interleaved boost converters are connected with the fuzzy logic controller produces high performance and reduced size with more reliable. II. INTERLEAVED BOOST CONVERTERS Interleaved boost converter mainly used for renewable energy sources has a number of boost converters connected in parallel, which have the same frequency and phase shift. It has additional benefits when comparing the general approaches of paralleling converters. These IBC`s are distinguished from the conventional boost converters by critical operation mode, Discontinuous Conduction Mode (DCM) and Continuous Conduction Mode (CCM).So that the devices are turned on when the current through the boost rectifier is zero. In the critical conduction mode the design becomes tedious as the critical point varies with load. Fig.1. Two phase interleaved PFC boost converter In the DCM, the difficulties of the reverse recovery effects are taken care but it leads to high input current and conduction losses and it is not best suited for high power applications. CCM has lower input peak current, less conduction losses and can be used for high power

2 applications. By dividing the output current into n paths higher efficiency is achieved and eventually reducing the copper losses and the inductor losses. The novel high voltage-boosting converters are presented. By changing the connection position of the anode of the diode and by using different pulse-width-modulation control strategies, different voltage conversion ratios can be obtained. These converters are constructed based on bootstrap capacitors and boost inductors. Above all, two boost inductors with different values, connected in series, can still make the converters work appropriately. Furthermore, although there are three switches in each converter, only one half-bridge gate driver and one low-side gate driver are needed, but no isolated gate driver would be needed. The conventional interleaved boost converter plays an important role in high-power applications and power factor correction. Unfortunately, there are some problems associated with this converter. The voltage stresses on semiconductor components are equal to output voltage. The Fig.1 shows the block diagram of two phase interleaved boost converter. Hence, based on the aforementioned considerations, modifying a conventional interleaved boost converter for high step-up and high-power application is a suitable approach. The conventional interleaved boost converter integrated with a Variant tolerant phase shifter to obtain it, and the Variant tolerant phase shifter is composed of switched capacitors and coupled inductors. The coupled inductors can be designed to extend step-up gain, and the switched capacitors offer extra voltage conversion ratio. In addition, when one of the switches turns off, the energy stored in the magnetizing inductor will transfer via three respective paths; thus, the current distribution decreases the conduction losses by lower effective current and also makes currents through some diodes decrease to zero before they turn off, which alleviate diode reverse recovery losses. Two-phase boost converter operates at a very large duty cycle due to a high output voltage and a low input voltage. It makes the stresses to the switches and the switch rating also high. It creates the losses, so efficiency decreased. block diagram of three-stage interleaved PFC boost converter. However the three-stage interleaved boost converter improves converter performance at the cost of additional inductors, switching devices and output rectifiers. The parallel connection of boost converters in high-power applications is a well-known technique. Its main advantage of the system stems from the fact that sharing the input current among the parallel converters allows smoothing some of the design constraints of the switching cells. It also has an added advantage that the switching and conduction losses are less in three-stage interleaved boost converter than the existing converter. The cancellation of low frequency harmonics eventually allows the reduction in size and losses of the filtering stages. III. BLOCK DIAGRAM EXPLANATION In the block diagram of the three-stage interleaved converter is supplied by single phase AC source, where the switching pulse to the Interleaved block is given by the pulse generator, which is the feedback pulse from load (Linear or Non-Linear). Fig.3. shows a proposed implementation of three-stage interleaved PFC boost converter. The block diagram consists of input AC source, three-stage interleaved converter, load and pulse generator and control unit. The circuit consisting of switched capacitors and diodes are connected with the primary inductance through three-stage interleaved boost converter switches. Fig.3. Proposed implementation of three-stage interleaved PFC Boost converter Fig.2. Three-stage interleaved PFC boost converter The proposed interleaved method is used to improve converter performance in terms of efficiency, size, conducted electromagnetic emission and transient response. To minimize the amount of ripples, a new IBC has been proposed in addition to which it has improved performance characteristics of higher power capability, reduced duty ratio and improved reliability, modularity. Fig.2. shows the A. Three-stage Interleaved Boost Converter The implementation of the three-stage interleaved PFC boost converter with the fuzzy logic control system is shown in the Fig.4. It consist of the combination of three set of single phase interleaved boost converters. So it having three switches inductors and diodes. The input given to the circuit is 230V ac supply from the line. Three-stage interleaved boost converter, which comprises three boost converters operating at 180 out of phase. The input current is the sum of the three inductor currents, I 1, I 2 and I 3. Because the inductor's ripple currents are out of phase, they cancel each other out and reduce the input-ripple current that the boost inductors cause. The best input-inductorripple-current cancellation occurs at 50% duty cycle. The output-capacitor current is the sum of the three diode currents, I 1, I 2, I 3, minus the dc-output current, which

3 reduces the output-capacitor ripple, I 0, as a function of duty cycle. As the duty cycle approaches 0, 50, and 100%, the sum of the three diode currents approaches dc. At this point, the output capacitor has to filter only the inductor-ripple current. The effective ripple frequency is thrice than that of a single-phase boost converter. The amplitude of the input current ripple is small. The gating pulses of the two devices are shifted by a phase difference of 360/n, where n is the Fig.4. Implementation of the three-stage interleaved PFC boost converter with the fuzzy logic control system number of parallel boost converters connected in parallel. It can be seen that the input current I, for three-stage interleaved boost converter is the sum of each channels induction currents. As the three devices are phase shifted by 180 degrees, the input current ripple produced is the smallest. B. Advantages of Three Phase IBC The amplitude of the input current ripple is small. Reduced capacitor current translates into smaller and less expensive capacitors. Doubling of ripple frequency makes smaller filter components. More compact in size due to smaller filter components. Higher efficiency due to lower conduction losses for a given input or load current. The transient response is improved by the result of smaller filter components. Reduction in peak currents translates into lower EMI noise generation. It allows single switch topologies to be used at power levels that single converters cannot handle. The three-stage IBC also having the low ratings of switches, stress and switching losses. IV. MATLAB SIMULATION The proposed system simulated using MATLAB/ Simulink. The three-stage interleaved PFC boost converter model having three MOSFETs as switches. The Fig.5 shows the simulation model of three-stage interleaved boost converter. It consists of Fuzzy logic controller, gain, reference voltage, unit delay, inductor, capacitor and pulse generator blocks. Initially the step block generates the step input, which is given to the controlled voltage source block. The controlled voltage source block converts the simulink input signal into an equivalent voltage source. The generated voltage is driven by the input signal of the block. The gate pulse generator generates the pulse and given to the MOSFET S 1. Firstly the device S 1 is turned ON and the devices S 2, S 3 are in OFF state. When S 1 is turned ON, the current in the inductor I 1 increases linearly. During this period energy is stored in the inductor L 1. After a half switching cycle of S 1, S 2 is also turned ON completing the same cycle of events. S 3 is in OFF state. So the current in the inductor I 2 also increases linearly. During this period energy is stored in the inductor L 2 and L 1. Now S 1 is turned OFF, diode D 1 conducts and the stored energy in the inductor ramps down with a slope based on the difference between the input and output voltage. The inductor starts to discharge and transfer the current via the diode to the load capacitor. But S 2 is still conducting and the energy is stored in the inductor L 2. The device S 3 is in OFF state. The same operation is takes place simultaneously for all switches and the final output is the combination of three BC. When the input is given to the primary, it is step up at the secondary of the coupling inductance. The diode performs the rectifier action. It is converted in to pure dc by the capacitor. Same action is takes place at the remaining two sets and the final output is combined at the output terminal. The voltage measurement block measures the instantaneous voltage between two electric nodes. The output provide simulink signal that can be used by other simulink block. Fig.5. Simulation model of three-stage interleaved boost converter

4 The inductor L 1 is starts to charge. The capacitor C 1 voltage and the load voltage are zero. Diode D 1 is forward biased and conducts charging up the pump capacitor, C1 to the peak value of the input voltage. Its starts to discharges and the diode D 5 turned to reverse bias. The same as capacitor also fully charged and its starts to discharges. Finally the capacitor voltage and inductor voltages are combined, this voltage is double of the input. The diode rectifies this voltage. Similar operation is performed in each phase. Finally the output is series combination of the out of all the phases. The rectified output is converted into pure dc by the terminal capacitor. The Fig.6 shows the programmable gate pulse generator model. The voltage measurement block measures the instantaneous voltage between two electric nodes. The output provide simulink signal that can be used by other simulink block. The constant block generates real or complex constant value. The block generates scalar, vector or matrix output depending on the dimensionality of the constant value parameter and the settings of the interrupt vector parameter. The desired output voltage is set as a constant integer value. The sum block performs the gain action on the constant set voltage and the reference voltage. The difference is given to the fuzzy logic controller. The fuzzy logic controller maintains the constant output voltage at the terminal of the system. The output signal from the mux is given to the fuzzy logic controller of the pulse generator. The two values given to the constant blocks with relational operator based on the production of the interleaved pulse. Fig.7. Simulation diagram of overall system The output values parameter specifies a vector of signal amplitudes at the corresponding output times. Together, the two parameters specify a sampling of the output waveform at points measured from the beginning of the interval over which the waveform repeats. The relational operator block compares two inputs using the relational operator parameter. The first input corresponds to the bottom input port and the second input to the top input port. The output value from the relational operator block is given to the pulse and finally generates the gate pulse. The Fig.7 shows the complete MATLAB/simulink model of the single phase bridgeless three-stage interleaved PFC boost converter with fuzzy logic controller along with the control circuit. V. RESULTS AND DISCUSSION In order to verify the performance of simulation results, three-stage interleaved boost converter with the input ripple current and voltage source as shown in Fig.8. Fig.6. Programmable gate pulse generator model The repeating sequence block outputs a periodic scalar signal having a waveform that you specify using the time values and output values parameters. The time values parameter specifies a vector of output times. Fig.8.Three-stage interleaved boost converter of ripple input source

5 The simulation performance of a single phase bridgeless three-stage interleaved boost converter with the fuzzy logic controller as shows the output current and voltage source. Fig.9. shows as three-stage interleaved PFC boost converter final output current source. been developed; it proves that the three-stage interleaved boost converter is having higher efficiency and reduced ripple content. The proposal increases the speed makes the system to work in both low and high power applications. REFERENCES [1] O. Garcia, J. A. Cobos, R. Prieto, P. Alou, and J. Uceda, Single phase power factor correction: A survey, IEEE Transaction on Power Electron., vol. 18, no. 3, pp , May [2] M. S. Elmore, Input current ripple cancellation in synchronized parallel connected critically continuous boost converters, in Proc. IEEE Application on Power Electron Conference., Mar. 1996, pp [3] J. R. Tsai, T. F. Wu, C. Y. Wu, Y. M. Chen, and M. C. Lee, Interleaving Phase shifters for critical-mode boost PFC, IEEE Transaction on Power Electron., vol. 23, no. 3, pp , May [4] X. Xu, W. Liu, and A. Q. Huang, Two-phase interleaved critical mode PFC boost converter with closed loop interleaving strategy, IEEE Transaction on Power Electron., vol. 24, no. 12, pp , Dec Fig.9.Three-stage interleaved boost converter final output current Fig.10. shows as simulation performance of three-stage interleaved PFC boost converter final output voltage source. As shown in the figure, the PFC boost converter with the proposed phase shifter shows the lowest input current ripple because the proposed variation-tolerant phase shifter provides the most accurate 180 phase shift. The PFC boost converter provides 410-V dc output from the ac input line voltage of V. [5] T. Ishii and Y. Mizutani, Power factor correction using interleaving technique for critical mode switching converters, in Proc. IEEE Transaction on Power Electron Specialist Conference., May 1998, pp [6] B. T. Irving, Y. Jang, and M. M. Jovanovic, A comparative study of soft switched CCM boost rectifiers and interleaved variablefrequency DCM boost rectifier, in Proc. IEEE Application on Power Electron Conference., Feb. 2000, pp [7] T. F. Wu, J. R. Tsai, Y. M. Chen, and Z. H. Tsai, Integrated circuits of a PFC controller for interleaved critical-mode boost converters, in Proc. IEEE Application on Power Electron Conference., Feb. 2007, pp [8] H. Choi, Interleaved boundary conduction mode (BCM) buck power factor correction (PFC) converter, IEEE Transaction on Power Electron., vol. 28, no. 6, pp , Jun [9] J. Sun, D. M. Mitchell, M. F. Greuel, P. T. Krein, and R. M. Bass, Averaged modeling of PWM converters operating in discontinuous conduction mode, IEEE Transaction on Power Electron., vol. 16, no. 4, pp , Jul Fig.10.Three-stage interleaved boost converter final output voltage A 486-W is the power efficiency and the power factor is 0.95pf of a single phase bridgeless three-stage interleaved boost converter with fuzzy logic control system has been proposed. VI. CONCLUSION This paper presents the principle and operation of threestage interleaved boost converter for single phase with bridgeless circuit. The various design parameters have been presented and analyzed. The simulation model circuit has