![]() ![]() Transformer-based converters may provide isolation between the input and the output. Usually, this is done to control the output voltage, the input current, the output current, or to maintain a constant power. The amount of power flow between the input and the output can be controlled by adjusting the duty cycle (ratio of on/off time of the switch). A bi-directional converter can move power in either direction, which is useful in applications requiring regenerative braking. However, almost all DC/DC converter topologies can be made bi-directional. The storage may be in either magnetic field storage components (inductors, transformers) or electric field storage components (capacitors).ĭC/DC converters can be designed to transfer power in only one direction, from the input to the output. In electric engineering, a DC to DC converter is a category of power converters and it is an electric circuit which converts a source of direct current (DC) from one voltage level to another, by storing the input energy temporarily and then releasing that energy to the output at a different voltage. The different configurations of EV power supply show that at least one DC/DC converter is necessary to interface the FC, the Battery or the Supercapacitors module to the DC-link. By introducing DC/DC converters one can chose the voltage variation of the devices and the power of each device can be controlled ( Schaltz & Rasmussen, 2008).ģ. This is again due to the nearly constant voltage of the battery. in a fuel cell battery configuration the fuel cell must provide almost the same power all the time due to the fixed voltage of the battery, and in a battery/supercapacitor configuration only a fraction of the energy exchange capability of the supercapacitor can be used. The voltage characteristics also have to match perfectly of the two devices, and only a fraction of the range of operation of the devices can be utilized, e.g. Each device might therefore be operated at an inappropriate condition, e.g. ![]() temperature, state-of-charge, health, and point of operation. The impedance depends on many parameters, e.g. However, in this way the power drawn from each device cannot be controlled, but is passively determined by the impedance of the devices. A simple configuration is to directly connect two devices in parallel, (FC/battery, FC/SC, or battery/SC). They can be connected to the fuel cell stack in many ways. Two often used energy storage devices are batteries and SC S. Thereby the system cost, mass, and volume can be decreased, and a significant better performance can be obtained. In EV the main energy source is assisted by one or more energy storage devices. This study takes into account the weight, volume, current and voltage ripples, Electromagnetic Interference (EMI) and the efficiency of each converter topology.Īn Electric Vehicle is a vehicle that uses a combination of different energy sources, Fuel Cells (FCs), Batteries and Supercapacitors (SCs) to power an electric drive system as shown in Fig. Simulations of 30KW DC/DC converter are carried out for each topology. The modeling and the control of each topology are presented. Thus, in this chapter, a comparative study on three DC/DC converters topologies (Conventional step-up dc-dc converter, interleaved 4-channels step-up dc-dc converter with independent inductors and Full-Bridge step-up dc-dc converter) is carried out. Due to the automotive constraints, the power converter structure has to be reliable, lightweight, small volume, with high efficiency, low electromagnetic interference and low current/voltage ripple. ![]() DC-DC converters can be used to interface the elements in the electric power train by boosting or chopping the voltage levels. Energy storage or supply devices vary their output voltage with load or state of charge and the high voltage of the DC-link create major challenges for vehicle designers when integrating energy storage / supply devices with a traction drive. MES provides extended driving range, and RESS provides good acceleration and regenerative braking. ![]() Most electric and hybrid electric configurations use two energy storage devices, one with high energy storage capability, called the “main energy system” (MES), and the other with high power capability and reversibility, called the “rechargeable energy storage system” (RESS). Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs) and Fuel Cell Electric Vehicles (FCEVs) have been typically proposed to replace conventional vehicles in the near future. Air pollution, global warming, and the rapid depletion of the earth’s petroleum resources are now serious problems. The large number of automobiles in use around the world has caused and continues to cause serious problems of environment and human life. ![]()
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