DOUBLE INPUT Z-SOURCE DC-DC CONVERTER Presented by  

ABSTRACT In this project presents a dynamic voltage restorer (DVR) that is characterized by the use of a high-frequency unidirectional isolated dc–dc converter is proposed. A traditional DVR has a large and bulky series transformer even for three-phase low-voltage up to 480-V applications because the transformer operates at the line frequency. This project discusses the control and performance of a low-voltage DVR using a high-frequency isolated dc–dc converter. The high-frequency transformer in the dc–dc converter is much smaller. Experimental results obtained from the prototype confirm the viability and effectiveness of the system configuration.

BLOCK DIAGRAM TMS PROCESSOR 5V DC SUPPLY 12V DC SUPPLY AC SUPPLY DRIVER CIRCUIT AC SUPPLY RECTIFIER AND FILTER Z SOURCE INVERTER LOAD

BLOCK DIAGRAM EXPLANATIONS Input supply:-DC Bridge rectifier:-It is used to convert AC voltage into Dcvoltage. Driver circuit:- It has two functions, a) Amplification b)Isolation. It can be used to amplify the 5V pulses to 12V for using transistor technology and provided isolations for using optocoupler. Dual Z source inverter:It is used to convert dc voltage into ac voltage. Load:- AC load

Rectifiers Here in our project for full wave rectification we use bridge rectifier. From the basic bridge configuration we see that two diodes(say D2 & D3) are conducting while the other two diodes (D1 & D4) are in off state during the period t = 0 to T/2.Accordingly for the negative cycle of the input the conducting diodes are D1 & D4 .Thus the polarity across the load is the same.

Filters In order to obtain a dc voltage of 0 Hz, we have to use a low pass filter. So that a capacitive filter circuit is used where a capacitor is connected at the rectifier output& a dc is obtained across it. The filtered waveform is essentially a dc voltage with negligible ripples & it is ultimately fed to the load.  

Power Supply Circuit

Inverters DC to AC converters are known as inverters. The function of an inverter is to change a dc input voltage to a symmetrical ac output voltage of desired magnitude and frequency. The output voltage could be fixed or variable at a fixed or variable frequency. A variable output voltage can be obtained by varying the input dc voltage and maintaining the gain of the inverter constant.

Driver Unit

Why Driver Circuit? This driver circuit, which produces amplified, pulses for the Mosfet’s power circuit, which uses emitter coupled amplifier circuit to boost the triggering pulse low voltage to the high voltage.

Advantages It is used to provide 9 to 20 volts to switch the MOSFET Switches of the inverter. Driver amplifies the voltage from microcontroller which is 5volts. Also it has an optocoupler for isolating purpose. So damage to MOSFET is prevented.

Circuit Description The diagram given above gives the circuit operation of the driver unit. The driver unit contains the following units. Optocoupler Totem pole Capacitor Supply Diode Resistor

Explanation Pulses from the microcontroller has given to the driver circuit for amplifying 5V to 12V pulses. The buffer CD4050 is used for the impedance matching. The optocoupler MCT2E is used for optical isolation. From the optocoupler transistor get the signal, this signal has amplified by using the totem pole configuration. This amplified signal has given across the terminals of gate & source of mosfet. To on the transistors, the power supply has given.

CIRCUIT DIAGRAM

EQUIVALENT CIRCUIT

CIRCUIT EXPLANATION State 1, both source 1 and source 2 are active shows equivalent circuit of this state. When both source1 and source 2 are active, the converter input dc voltage is sum of voltage of two series dc sources. In this state, because both two sources are active, D1 and D2 are forward biased and D3 and D4 are reverse biased. Thus the sources current enters in Z-network through D1 and D2 and after passing load impedance, comes back into sources through negative polarity. State 2, source 1 is active and source 2 is inactive In this state, source 1 is active, so only this source provides converter (consequently load) energy. Because of source 1 is active then D1 is forward biased and D3 is reverse biased, so Current follows from D1 to Z-network to load.

State 3, source 1 is inactive and source 2 is active If source 1 is eliminated for each reason and source 2 is active, the converter can operate normally without effect of source 1 elimination.In state 3, it’s only source 2 that supplies converter and load. Source 2 activation causes forward bias of D2 and reverse bias of D4. Because of source 1 disconnection, current passes through D3 and indeed, current turns it on forcedly to complete current path. In this state, converter input dc voltage is only provided by source 2. State 4, both source 1 and source 2 are inactive Basically, this state is only following of one of the previously mentioned three states. Because in this state both dc sources are inactive and disconnected from converter, D1 and D2 are forcedly turned off and consequently, the only existing path for remain current, from previous state, is provided by D3 and D4. Thereupon, in state4 D3 and D4 are turned on.

What is MATLAB? MATLAB is a high performance interactive software package for scientific and engineering computation. MATLAB integrates numerical analysis, matrix computation, signal processing and graphics in an easy-to-use environment where problems and solutions are expressed just as they are written mathematically. To start MATLAB on our system just type matlab in a terminal window or find the Matlab icon in the panel.

Desktop Environment

Simulink Basics

What is Simulink Simulink is a software package for modeling, simulating and analyzing dynamical systems. It supports linear and nonlinear systems, modeled in continuous time, sampled time, or a hybrid of the two. Simulink offers a friendly, graphical environment, in which you can model systems in the form of block diagrams, by simply clicking and dragging blocks into a model window. Simulink has a comprehensive block library of sinks, sources, subsystems (linear, nonlinear, and time-varying

Simulink Blocks Unused input terminals are indicated by a small open triangle. Unused output terminals are indicated by a small triangular point. Blocks have zero to several input terminals and zero to several output terminals.

Starting Simulink Start Matlab Write in Command Window simulink New… Model Drag and Drop components from the libraries to the Model Double click on component to edit parameters Wire components together right button down and drag wire activate output, hold CTRL and click on input

Simulation design

Simulation output

Output waveform

Pulse waveform

ADVANTAGES Improved efficiency Low switching losses Low voltage stress

APPLICATION Industrial appliance improve the reliability. Boosting feature of converter makes it proper for new energy applications.

CONCLUSION In this project double input Z-source dc-dc converter is proposed. The operation principle, including the operation modes and steady-state analysis is explained in detail. The analysis and simulation results show the input dc sources can deliver power to the load individually or simultaneously, as failure of each input sources doesn’t disturb the other’s operation. Two input sources can have different characteristics and voltage. Also, converter controls output power with only one active switch which can reduce cost and improve the reliability. Boosting feature of converter makes it proper for new energy applications

REFERENCES: E. Milady and H. E. McKenna, “Power quality issues in a hybrid power system,” IEEE Trans. Ind. Appl., vol. 38, no. 3, pp. 803-809, May/Jun 2002.   F. Giraud and Z. M. Salameh, “Steady-state performance of a gridconnected rooftop hybrid wind-photovoltaic power system with battery storage,” IEEE Trans. Energy Convers., vol. 16, no. 1, pp. 1-7, Mar 2001. Yaow-Ming Chen, Yuan-Chuan Liu, and Sheng- sien Lin, “DoubleInput PWM DC-DC Converter for High-/Low-Voltage Sources,” IEEE Trans. Ind. Electron., vol. 53, no. 5, October 2006.   Yuan-Chuan Liu and Yaow-Ming Chen, “A systematic approach to synthesizing multi-input dc–dc converters” IEEE Trans. Power Electron., vol. 24, no. 1, January 2009.

Thank You