DESIGN AND IMPLEMENTATION OF CONVERTERS FOR ELECTRIC VEHICLE APPLICATIONS

Abstract

Contemporary scientific and technical developments have enabled modern electronics to become more-compact and portable. The power electronics converters are playing crucial role in most of modern electronics gadgets that makes them appealing and practical. Different types of power electronic converters are utilized nowadays, like as DC-DC (chopper), AC-DC (rectifier), DC-AC (inverter), and AC-AC (Cyclo Converter). Each of them has a particular use and is employed in some power electronics system. The present work demonstrates design and implementation of wireless power transfer (WPT) scheme using power electronics converter technology and also active clamp forward converter (ACFC). Since power electronics are becoming more-small and portable by day, Wireless Power Transfer would be a interesting option for small and medium power charger for battery charging in electric vehicles (EVS). WPT is advantageous owing with two fundamental battery issues: short battery life and high initial cost. Several technologies have been proposed to increase the Wireless Transmission (WPT) capacity across a changeable range. Capacitive, inductive, & magnetic resonant coupling are some of the approaches for transferring wireless power, however these couplings do have limit on the power transfer values & range, indicating the inherent trade-off among distance & power transferred. This project is about using WPT for battery charging. There are three major sections in WPT: Conversion from DC-AC, wireless power transfer and AC- DC conversion. A single-switch resonant inverter will be used for DC-AC conversion to improve efficiency by eliminating component ON and OFF state losses. Magnetic Resonance Coupling (MRC) is used to transmit electricity wirelessly between two coils that function as sender and receiver. Eventually, a high frequency diode rectifier is employed to generate a DC output for charging the batteries. For the power amplifier, a class-E inverter is used, which works on a single-switch resonance phenomenon. The Class-E inverter does have the advantage of reducing switch stress. The converter operates at a switching frequency of 100 KHz & an efficiency of roughly 85.74 percent due to its single-switch design. High frequency operation reduces the size of the circuit components such as inductor and capacitor. MRC was used for WPT because it is more efficient for power transfer range over a variable distance in comparison to capacitive Delhi Technological University Page iv and inductive resonant coupling. To acquire the most bandwidth for power transmission, an impedance matching approach is utilised. The DC output was obtained using a full bridge rectifier circuit, which is used to charge a battery. Active Clamp Forward Converter is a DC-DC converter with isolation which may be utilised for a wide variety of power of 50W to 500W i.e., for low-power applications, the ACFC is a common choice for single and/or multiple output power-supply. Active Clamp Forward Converter is used to harness power from battery of electric vehicles and transmit it to power up various other parts of electric vehicles. Active clamp forward converters are smaller and more efficient than passive clamp forward converters. In forward converter transformer’s are utilised to accomplish circuit isolation and energy transformation from primary side to secondary side, as well as to reset the transformer's magnetising current using the active clamp approach. While there are a variety of approaches for accomplishing transformer reset, the active clamp approach is both simple and effective. ZVS (zero voltage switching), decreased switch voltage stress, wider duty cycle range, and reduced EMI (electro-magnetic interference) are just a few of the benefits of active switching. The active clamp approach uses a normal pulse width modulation (PWM) system to transmit power and the switch is switched on at zero voltage-switching (ZVS) utilising transformers leakage-inductance (LL) and parasitic capacitance and/or switch-output capacitance (CDS). In this project efforts have been made to design a ACFC DC to DC converters for EV applications. The converter topology is simulated in MATLAB/Simulink and it’s conversion capacity is demonstrated through relevant waveform and figure.