Push-Pull Quasi Resonant Converter Techniques used for Boost Power Factor Corrector

Push-Pull Quasi Resonant Converter Techniques used for Boost Power Factor Corrector

V. Siva Subramanyam K. Chandra Sekhar

PG student, Department of EEE Assistant Professor, Department of EEE Siddhartha institute of science and technology Siddhartha institute of science and technology

Chittoor (D), Andhra Pradesh, India Chittoor (D), Andhra Pradesh, India

R. Ramesh T Kishore Babu

PG student, Department of EEE PG student, Department of EEE Siddhartha institute of science and technology Siddhartha institute of science and technology

Chittoor (D), Andhra Pradesh, India Chittoor (D), Andhra Pradesh, India

AbstractThis project presents a power-factor corrector (PFC), which is principally composed of 2 section transition- mode (TM) boost-type power-factor correctors (PFCs) and a coupled inductor. By desegregation 2 boost inductors into one core, not solely the circuit volume is reduced, however additionally the operative frequency of the core is double of the switching frequency. Therefore, the power-factor price and also the power density are enhanced. A cut-in 0.5 duty cycle will cut back the physical phenomenon losses of the switches and each of the turns and diameters of the electrical device windings. The benefits of a metallic element boost greenhouse emission, like quasi-resonant (QR) depression change on the switch and zero- current switching (ZCS) of the output diode, are maintained to boost the conversion potency

Keywords push pull topology, coupled inductor, quasi resonant converter

1. INTRODUCTION

   Generally boost conveter topology is the most commonly used technique to improve the power factor. It is always neceesary to rech power factor as unity a cost effective solution can be obtained for greater than 0.95.In this proposed system we are using the push-pull technique to boost up the voltage level up to 380V dc for an input of 110 V ac supply.

   A pushpull converter is a type of DC-to-DC converter that uses a transformer to change the voltage of a DC power supply. The proposed system having the capable of operating three modes of operation they are Continuous Conduction Mode, Discontinuous Conduction Mode and Transition Mode.

   Even though Continuous Conduction Mode best suitable for high power applications the inductor value in this mode is high and in case of Discontinuous Conduction Mode the input harmonics level is high. But in case of transition mode the inductor value is moderate and useful for medium power applications so this mode is used for the proposed topology.

   Derived from 2 TM boost converters with the interleaved operations, the power rating is increased and the input current and output current are shared equally with lower

   current ripples. Therefore, the total harmonic distortion (THD) of input current and the output capacitance can be reduced. However, the need of two inductors with two independent cores increases the circuit volume.

   In this paper, a pushpull boost PFC composed of two interleaved TM boost PFCs and a coupled inductor is proposed and a single magnetic core is used. The two identical modules can share the output power and promote the power capability up to the medium-power-level applications.

   In addition to this coupling of the two distributed boost inductors into a one magnetic core automatically reduces the circuit volume, which is the important goal of the development of switching power supply today. The interleaved operations of the switches act like a pushpull converter. The difference is that the operating frequency of the core is getting double of the switching frequency, which means that not only the circuit size is reduced and also the operating frequency of the core is getting double of the switching frequency.

   The same distributions of the input current and output current, the proposed topology with a cut-in 0.5 duty cycle can reduce the conduction losses of the switches on both the turns and diameters of the inductor windings

   It is also maintains the advantages of a TM boost PFC, such as QR valley switching on the switch and zero- current switching (ZCS) of the output diode, to reduce the switching losses and improve the conversion efficiency.

   MATLAB/SIMULINK used for the proposed system to simulate for an universal line voltage of 110v ac, a 380-V output dc voltage and a 200-W output power in order to verify its feasibility.

2. CIRCUIT TOPOLOGY

   Fig 1 shows block diagram for push-pull Qusi Resonant converter. Here the power conversion occurs in three segments. In the first segment single phase AC supply is fed to the rectifier, to convert AC to DC. The output from the rectifier is modulated sinwave. This modulated sinwave is given to the quasi resonant converter. Using quasi resonant converter the voltage has been boosted. Then it is given to the load.

   Fig.1. Block diagram of push-pull Quasi Resonant converter

   1. Circuit Diagram Of Push-Pull Quasi resonant Converter

      The circuit diagram for push- pull quasi resonant converter is shown in fig below. First we are converting ac voltage into dc voltage by using rectifier. The output from the rectifier is modulated sinwave then this supply is given to the push pull quasi resonant converter. This quasi resonant converter boost up the voltage to 380V. The proposed topology is operated by transition mode with constant on time and variable frequency.

      The proposed topology consists of two modules. Module A consists of the switch Sa , the winding NPa , the inductor La , and the output diode Da . Module B consists of the switch Sb, the winding NP b , the inductor Lb, and the output diode Db. These two modules have a common output capacitor Co . La and Lb are 2 coupled windings wound on the same magnetic core.Theoretically, the same turns of these two windings will lead to the same inductances

      Coupled without leakage inductance. In addition, The turns of the windings NPa and NPb will be same. Therefore, La and Lb are also matched

3. OPERATION MODES IN QUASI RESONANT

   CONVERTER

   The operating modes of the proposed topology are analyzed as follows

   Fig.2.push pull quasi resonant converter

   To analyze the operating principles, there are some assumptions listed as follows.

   .

   1. The conducting resistances of Sa and Sb are ideally zero.

      Fig.3 key wave forms for proposed topology

      The conduction time interval is DTs , where D is the duty Cycle and Ts will be the switching period.

      1. Mode 1 operation: t0 < t < t1

         Referring to Fig. 4, in module A, Sa

         conducts.

   2. The forward voltages of Da

      and Db

      are ideally zero.

      Thus, the voltage across NPa equals to the rectified line- in voltage Vin . The inductor current iL a increases linearly,

   3. The magnetic core for manufacturing La

   perfectly

   and Lb is

   and Da is reverse-biased. In module B, Sb is turned OFF. The voltage across NPa is coupled to NP b . Hence, the voltage across NPb is also Vin, and the dotted terminal is positive. Lb stores energy as La does. The inductor current iLb increases linearly and flows into the non dotted terminal of NP b . By the coupling effect, this current flows

   into the dotted node of NPa . Since the voltage across Sb is zero, Db is also reverse-biased. Co supplies the energy to the load. The constant turn-on time of Sa is decided by the management of the controller depending on the rectified line-in voltage Vin. This is the initial mode of operation.

   Fig.4. module A Sa ON, module B Sb OFF

4. Mode 2 operation: t1 < t < t2

   As shown in Fig. 5, in module A, Sa is turned OFF. Da conducts for iLa to flow continuously. La releases its energy to Co and the load. The voltage across NP is (Vo Vin ) and the dotted terminal is negative. In module B, Sb is still turned OFF the voltage across NPa is coupled to NPb.

   Hence, the voltage across NPb is also (Vo Vin ), and the dotted node is negative. Db is thus forward-biased to carry the continuous iLb. Lb is also releases its energy to Co and the load. Both iLa and iLb are decreasing linearly. This state ends until La and Lb release their energies completely, and iLa and iLb decrease to zero.in this mode we are boosting the voltage.

   Fig 5 Module A Sa OFF Module B Sb OFF

5. Mode 3 operation: t2 < t < t3

As shown in Fig. 6, in module A, Sa keeps turned OFF. At t2, Da is turned OFF with ZCS since iLa decreases to zero natu- rally. Similarly, in module B, Sb is still turned OFF. Db is turnedOFF with ZCS at t2 since iLb decreases to zero naturally, too.In this interval, Co supplies the energy to the load. At the sametime, in module A, the series resonant loop formed by Vin, theparallel connection of La and Lb, and the output capacitance ofthe switch Sa, Cossa, starts to resonate. Similarly, in module B,the series resonant loop formed by Vin, the parallel connectionof La and Lb, and the output capacitance of the switch Sb, Cossb,begins to resonate. Therefore, vDSa and vDSb decrease simulta-neously. This mode is helpful to increasing the power factor.

Fig.6. Module A Sa OFF Module B Sb OFF S1

In this paper, a novel of push pull quasi resonant converter techniques for Boost PFC is implemented in order to boost up the voltage level and improve the power factor. Simulation has been done using MATLAB/SIMULINK for an input voltage of 110V AC for both open loop and closed loop system. In both the systems we are gaining the power factor near by unity.

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