Mathematical Modeling, Design and Analysis of LLC-T Series Parallel Resonant Converter

This paper represents a modified LCL-T (inductor inductor capacitor) series parallel resonant converter (SPRC) has been mathematically modeled and validated. The limitations of two element resonant topologies have been removed by adding a third reactive element. The study indicates the mathematical modeling and design of LCL-T SPRC. The proposed approach is expected to provide better voltage regulation for dynamic load conditions. The analysis shows that the output of converter is free from the ripples, and has constant current, regulated output voltage. The analysis is carried out using the state space approach. The study indicates the superiority of SPRC over series or parallel resonant converter. The results show that the output of converter is free from the ripples, constant current, regulated output voltage and these converters can be used for many airborne applications. Key-Words: Resonant Converter, ZVS, ZCS, Power Electronics, State Space Analysis. I.INTRODUCTION RESONANT converters (RCs) feature zero-voltage switching (ZVS), zero-current switching, high-frequency operation, high efficiency, small size, and low electromagnetic interference. RCs have been successfully applied to many applications including constant-voltage (CV) dc power supplies, constant-current (CC) power supplies, high-frequency ac power supplies for induction heating, power factor correction, and discharge lamp ballast. An important area of application of RCs is high-voltage (HV) power supplies. The design of a high voltage (HV) power converter is complex because of high leakage inductance and winding capacitance associated with the transformer. Since these parasitic components can easily be integrated as a part of resonant network, RCs are popularly applied for these applications. [1] Aims to develop a fast and efficient power supply using an LCL type resonant converter configuration. For ease of use, the entire system is monitored by a microcontroller which controls the power output and monitors the power supply. In recent years the design and development of various DC-DC Resonant Converters (RC) have been focused for electrical, electronics, telecommunication and aerospace applications. It has been found that these converters experience high switching losses, reduced reliability, electromagnetic interference (EMI) and acoustic noise at high frequencies. The Series Parallel Resonant Converters (SPRC) is found to be suitable, due to various inherent advantages. The series and parallel Resonant Converter (SRC and PRC respectively) circuits are the basic resonant converter topologies with two reactive elements. The merits of SRC include better load efficiency and inherent dc blocking of the isolation transformer due to the series capacitor in the resonant network. However, the load regulation is poor and output-voltage regulation at no load is not possible by switching frequency variations. On the other hand, PRC offers no-load regulation but suffers from poor load efficiency and lack of dc blocking for the isolation transformer. It has been suggested to design Resonant Converter with three reactive components for better regulation.[8], [9] II.PROPOSED LCL-T SERIES PARALLEL RESONANT CONVERTER LCL-T SPRC is expected the speed of response, voltage regulation and better load independent operation. Keep the above facts in view, the LCL-T SPRC has been module and analysised for estimating various responses. The closed loop state space module has been derived and simulate using MAT LAB/Simulink for comparing the performance with existing converter. [1], [2], [3] Mathematical Modeling, Design and Analysis of LLC-T Series Parallel Resonant Converter Second International Conference on Emerging Trends in engineering (SICETE ) 20| Page Dr. J.J. Magdum College of Engineering, Jaysingpur Figure 1: LCL-T Series Parallel Resonant Converter LCL-T RC is an attractive alternative for HV power supplies due to its own merits. Many applications of Resonant Converters are as: HV pulsed load application. HV dc power supply for medical application like X-ray generator is popularly developed using PRC. SRC with voltage multiplier. HV ac power supply in corona discharge process for rendering affinity of polyethylene film to ink or glue using transformer leakage inductance and electrode capacitors. HV power supply for electrical discharge machining. High-power electrostatic precipitators using LCC RC. Ozone generation using LCC RC. The use of third-order resonant tank for megahertz range HV-ac power supply for low temperature plasma generation. The high-power industrial application of CO2 laser also needs HV power supply. III.MATHEMATICAL MODELING 3.1 Assumptions in State Space Analysis Mathematical modeling of proposed converter was done using state space analysis.[1] The following assumptions are made in the state spare analysis of the LCL Resonant Full Bridge Converter. 1) The switches, diodes, inductors, and capacitors used are ideal. 2) The effect of snubber capacitors is neglected. 3) Losses in the tank circuit are neglected. 4) DC supply used is smooth. 5) Only fundamental components of the waveforms are used in the analysis. 6) Ideal High Frequency transformer with turns ratio n =1. Figure 2: Equivalent Circuit Model of LCL –T SPRC. \ The equivalent circuit shown in Figure 1 is used for the analysis. The vector space equation for the converter is: X = AX + BU 1 Y = CX + DU Where,