![]() Iyer, Power Electronic Converters – Interactive Modelling Using Simulink, CRC Press, 2018. Kazimierczuk, Pulse-Width Modulated DC-DC Power Converters, 2nd Edition, Wiley, 2016. Dokić, Branko Blanuša, Power Electronics Converters and Regulators, 3rd Edition, Springer, 2015. Seref Soylu, Electric Vehicles Modelling and Simulations, IntechOpen, 2011. Ali Emadi, Advanced Electric Drive Vehicles, CRC Press Taylor & Francis Group, 2015. In the following articles we are going to discuss about the modes of operation of DC-DC converters, derive the their mathematical models and perform simulations using Scilab/Xcos. Thus, according to the power module packaging, as well as the used heat sink, maximum allowed current can vary for the same device.įor automotive applications, a DC-DC converter must meet several design requirements, like: Maximum allowed current does not only depend on the module rating but also on the thermal properties of the semiconductor. Semiconductors are rated in terms of the maximum voltage they can handle and still behave as an insulator, and the maximum current that can circulate through them without damaging the device. This dual function defines what a semiconductor is: a device which is able to conduct current in an efficient way, as well as to block it. Hence, they have two roles: as an electrical conductor to close the circuit, as well as an electrical insulator to break/open the circuit. In a DC-DC converter the switching devices (S) have to open and close an electrical circuit. The Zeta converter is another option for regulating an unregulated input-power supply. Unlike the SEPIC converter, which is configured with a standard boost converter, the Zeta converter is configured from a buck controller that drives a high-side PMOS FET. ![]() The Zeta converter also needs two inductors and a series capacitor, sometimes called a flying capacitor. Similar to the SEPIC DC/DC converter topology, the Zeta DC-DC converter topology provides a positive output voltage from an input voltage that varies above and below the output voltage. Switch type DC-DC converters have better efficiency compared with linear converters because they are not continuously dissipating power. However, switching losses reduce the efficiency at high frequencies, the higher the switching frequency, the higher the power losses. Therefore, the conduction losses are low and the efficiency of switching-mode converters is high, usually above 80% or 90%. The voltage drop across the transistors is very low when they conduct high current and the transistors conduct a nearly zero current when the voltage drop across them is high. In switching DC-DC converters, transistors are operated as switches, which means that they dissipate much less power than transistors operated as dependent current sources. For this reason, linear DC-DC converters are usually used for low power applications. Without suitable cooling the linear DC-DC converter can overheat and destroy itself. \Īll that dissipated power is going to be converted into heat. The electric power P is the product between voltage U and electrical current I. The storage of the electric energy may be done in either magnetic field storage components (inductors, transformers) or electric field storage components (capacitors). ![]() ![]() 12 V), for conventional 12 V loads (lights, multimedia, power windows, etc.).Ī DC-DC converter is a power converter that 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. 400 V) to low direct current voltage (e.g. The DC-DC converter in a Battery Electric Vehicle (BEV) is used to convert the high battery voltage (e.g. Depending on the operating point of the DC-DC converter (voltage and current) and the type of converter, the efficiency can be between 75 % to 95 % or more. The conversion from one voltage level to another voltage lever is done with some power losses. If we have two electrical systems, operating at different voltage levels, one high level (140 V) and another one low level (14 V), a DC-DC converter can convert the voltage between them, from high to low or from low to high. ![]() Image: Principle of operation of a DC-DC converter ![]()
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