I. INTRODUCTION III. PROPOSED SYSTEM. A. Block Diagram

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1 Four Switch Hybrid Converter for AC and DC Loads 1 P.A.Kalpana, 2 K.Jansi Rani, 3 N.Hephzi Jayarani, 4 G.Monisha and 5 Mrs. S. Meenakshi, 1,2,3,4 Student, 5 Assistant Professor, 1,2,3,4,5 Department of Electrical and Electronics Engineering, VelTech Engineering College, Avadi, India Abstract: The consumption and usability of electricity is increasing in our day to day life. So the proposed system gives the best result which has new Hybrid Convertor (BDHC) which can supply DC as well as AC from a single DC Source. The Conventional Hybrid Convertor has single switch controlled boost and Buck Boost convertor is been replaced by Boost Derived Hybrid Convertor (BDHC) which got Voltage Source Inverter. Advantage of using VSI will reduce number of switches and separate convertor for supplying AC & DC loads. PIC Microcontroller is additional used to control the voltage source inverter using PWM (Pulse Width Modulation) to generate sine curve. The shoot through problem in conventional hybrid converter is recovered and turned as an advantage in the proposed system for higher gain. Keywords: Boost Derived Hybrid Converter (BHDC), Pulse width modulated inverters, PIC controller. I. INTRODUCTION The Introduction of NANOGRID Architectures is being progressively more integrated in present electrical and electronic power systems. These systems include distinct types of loads based on their application both on AC as well as DC which are interfaced with their energy sources by using power convertors. In the existing conventional method, two separate power converters are used for each conversion type (DC-DC) and (DC-AC). In the proposed system a Boost derived hybrid converter is employed which performs both conversion type of operations at the same time i.e., combination of both converter and an inverter [1]. Proposed system requires less number of electronic components like switches and passive components when compared to existing system due to this switching losses are reduced to dead circuitry used by the VSIs s to put off shoot throughout problems. In adding up to that, due to Electro Magnetic Interference (EMI) which leads to misgating turnon of the inverter leg switches may takes place ensuing in damage to the switches. To control the EMI induce misgating signal through working of conventional VSI is more reliable. II. CONVENTIONAL SYSTEM The existing conventional system is made up of two separate converters, a DC DC converter (can be said as boost converter) and a Voltage Source Inverter (VSI), connected either in cascade or in parallel form, supplying AC and DC outputs at VACout and VDCout respectively. Based on the requirements, topologies providing higher gains may be essential to achieve step up operation. The Dead time circuitry is enabled in the operation of VSI s Hybrid converters to prevent shoot through. A. Block Diagram Figure 1: Dedicated power converter based architecture The conventional hybrid converter is connected to nonconventional energy sources to provide cleaner and safer energy. Due to these space constraints, the dedicated energy sources are highly localized resulting in low power ratings and terminal voltage. Conventional designs are made up of two separate converters namely boost and voltage source inverter (VSI) which is either connected in parallel or in cascade form. B. Circuit Diagram Figure 2: Conventional Circuit Diagram The voltage source inverter is connected in parallel supplying ac and dc outputs at VACout and VDCout, respectively. The operation of VSI s in hybrid converters would involve the usage of dead time circuitry inorder to prevent shoot through control, which is caused due to electromagnetic interference (EMI) or noise that is produced in the circuit, the another issue is inverter leg switches may turn on and cause damages to the switches. Compactness of the overall conversion system is the generation of false noise and the VSI s in applications need to be exceedingly reliable with measures against EMI - Induced misgating. A. Block Diagram III. PROPOSED SYSTEM Figure 3: Block diagram of proposed system B. Voltage Source Inverter Bridge Network A Bidirectional single-phase bridge network switch (Q1 Q4) and diode is replaced in the place of control switch of a conventional boost converter to obtain the BDHC topology. Due to the above replacement the proposed converter provides simultaneous AC output (VACout) in addition to the DC Available Online@ 74

2 output (VDCout) provided by the boost converter. For the BDHC, the hybrid (DC as well as AC) outputs have to be controlled using the same set of four controlled switches that are available in the bridge network circuit Q1 Q4. In proposed method, the boost operation can be done by turning on either leg s1 - s4 or other two switches simultaneously. This will be equal to shoot through condition. The ac output is controlled by unipolar sine PWM switching scheme[2]. The circuit state of BDHC is equivalent to conventional VSI during inverter operation. The input to the inverter is given by switch node voltage (VSN). It jumps between the two voltage levels. In this mode of operation current and voltage in the circuit is almost zero in ac and dc circuit If this type of system continuous switches in the circuit may get failure. B. Interval II Power interval Figure 4: Circuit diagram of proposed system IV. OPERATION OF BDHC The operation of converter can be performed by turning on both the switches (Q1 Q2 or Q3 Q4) simultaneously. The above performed process results in generation of sine wave in circuit. Hybrid converter topologies can be analyzed by replacing the controlled switch with an inverter bridge network, either in single-phase or three-phase one. The control switch of a boost converter has been replaced by the bidirectional bridge network switches (Q1 Q4) to obtain the BDHC, converter provides simultaneous both the AC output (VACout) as well as the DC output (VDCout) provided by the boost converter [3]. The BDHC has three switching intervals Interval I Shoot-through interval Interval II Power interval Interval III Zero interval A. Interval I Shoot - through interval Figure 5: Power Interval During this time interval, the Diode D conducts and the voltage at the switch node (Vsn) is equal to the VDCout (neglecting the diode voltage drop). In this interval, either one of Q1 Q2 or Q3 Q4 is turned on. The power interval is the proper way to generate DC as well as AC from the circuit. Turning on the switches Q1 Q2 or Q3 Q4 will generate a proper sine wave and in which the dc circuit will be in active mode [4]. C. Interval III Zero interval Figure 6: Zero Interval The diode D conducts during this interval. The DC supply to the circuit is turned off, voltage in a circuit becomes zero, current in the capacitor discharge slowly. Table 1: Steady-State Expressions of BDHC in Different Modes Of Operation Figure 4: Shoot - through interval The shoot-through interval occurs when both the switches (either Q1 Q4 or Q3 Q2) are turned on at the same time During this period, the Diode D is reverse biased. The inverter output current circulates within the bridge network switches. Available Online@ 75

3 Table 2: Theoretical Graph 2) Triggering Pulse Figure 8: Input Voltage V. WHY DO WE GO FOR A NEWER SYSTEM Lesser number of passive components. The number of controllable switches in the proposed system are reduced, compared to the conventional boost cascaded inverter topology. The boost converter has higher switching frequency, thus reducing the magnetic size and improvements in the dynamics of the system. The converter can also be adapted to generate ac outputs at frequencies other than line frequencies. A. Circuit Diagram VI. SIMULATION DIAGRAM 3) AC Output Voltage Figure 9: Triggering Pulse 4) AC Output Current Figure 10: AC Output Voltage B. Results 1) Input Voltage Figure 7: Simulation Circuit Diagram Figure 11: AC Output Current Available Online@ 76

4 5) DC Output Voltage 6) DC Output Current Figure 12: DC Output Voltage b) Output waveform (AC) Figure 15: Input waveform 54.2v is obtained as a output from the inverter operation. The higher of frequency 33.2MHZ is achieved which gives a peak voltage of 20.4v. Figure 13: DC Output Current VII. EXPERIMENTAL VERIFICATION For experimental verification, a 20v input is given to the boost derived hybrid converter and supplies simultaneously AC (60v) and DC (54.2v) loads. A PIC16F877A is used as a feedback controller for triggering the pulses. For current gain, 4244 buffer is implemented[5]. A gate driver FA7392 is used for isolation. For converting AC to DC a regulator of 7305 and 7312 are used. Figure 16: Output waveform c) Output voltage waveform (DC) A 60v dc output is obtained by the boost operation. Figure 17: Output Voltage waveform VIII. SIMULATION AND RESULTS A. Experimental Waveform a) Input waveform (DC) Figure 14: Zero Interval From a battery source, 20v is given as a input to the boost derived hybrid converter. Figure 18: Result The above figure shows DC and AC outputs from a single DC source[6]. A 48V is given as a input which is able to Available Online@ 77

5 supply dc and ac loads at 100V and 110 V (RMS)[7]. The dc voltage is depends on the Duty Cycle Ratio (DST) and the AC load is depend on both duty cycle and Modulation Index (Ma). CONCLUSION Thus the proposed paper has given a detailed description about hybrid converter topologies which can supply both AC and DC loads simultaneously. The hardware performance will give a 65 V output from 12 V input that is used to run a motor and LED strip simultaneously for residential applications. Experimental results of BDHC will be achieved in open loop condition. The dynamics and magnetic size is reduced in proposed modification and higher gains are achieved in quadratic boost converter. Acknowledgment I am grateful to thank my guide Mrs.S.Meenakshi for helping me formulate this paper. I would also to thank my friends and family for their support and co operation which helped me to complete this technical paper in a successful manner. References [1] D. Boroyevich, I. Cvetkovic, D. Dong, R. Burgos, F. Wang, and F. Lee, Future electronic power distribution systems A contemplative view, in Proc. 12th Int. Conf. OPTIM Elect. Electron. Equip., Brasov, Romania, May 20 22, 2010, pp [2] F. Blaabjerg, Z. Chen, and S. B. Kjaer, Power electronics as efficient interface in dispersed power generation systems, IEEE Trans. Power Electron., vol. 19, no. 5, pp , Sep [3] O. Ray, S. Mishra, A. Joshi, V. Pradeep, and A. Tiwari, Implementation and control of a bidirectional high-gain transformer-less standalone inverter, in Proc. IEEE Energy Convers. Congr. Expo. Raleigh, NC, USA, Sep. 2012, pp [4] F. Z. Peng, Z-source inverter, IEEE Trans. Ind. Appl., vol. 39, no. 2, pp , Mar./Apr [5] C. J. Gajanayake, F. L. Luo, H. B. Gooi, P. L. So, and L. K. Siow, Extended-boost Z-source inverters, IEEE Trans. Power Electron., vol. 25, no. 10, pp , Oct [6] Jince Jose, Emmanuel Babu, Aleyas.M.V, Boost & Buck-Boost Derived Hybrid Converter for Simultaneous DC & AC Applications, e-issn: X, p-issn: X, Volume 10, Issue 2 (February 2014), PP [7] Pradipta Patra, Amit Patra, A Single-Inductor Multiple-Output Switcher With Simultaneous Buck, Boost, and Inverted Outputs, Ieee Transactions On Power Electronics, Vol. 27, No. 4, April Available Online@ 78