Elektrotoplinsko modeliranje i simulacija učinskog MOSFET-a

Electro-thermal simulation of power electronic semiconductors is now required in accurate optimisation of power electronic circuits and systems. This requires accurate, but not too complex, electro-thermal models of power semiconductors to be used in commercially available power electronic circuit simulators. Realization of one such electro-thermal model for power MOSFET in IsSpice is described in the paper. Model consists of electrical and thermal part with interactive exchange of variables. Electro-thermal model was tested on real circuit example.Za postizanje što bolje optimizacije sklopova i sustava energetske elektronike danas se zahtijeva elektrotoplinska simulacija učinskih poluvodičkih sklopki. Za to su potrebni točni, no ne i presloženi elektrotoplinski modeli učinskih poluvodičkih sklopki, pogodni za primjenu u tržišno dostupnim simulatorima sklopova energetske elektronike. U članku je prikazana IsSpice realizacija elektrotoplinskog modela učinskog MOSFET-a. Model se sastoji od električnog i toplinskog dijela koji međusobno izmjenjuju vrijednost varijabli. Elektrotoplinski model ispitan je mjerenjem na stvarnom sklopu

Optimizing braking energy flow through charging status surface expansion

Energy savings in electric railway transportation is essential due to the ever-rising energy cost and endeavour to reduce climate change impact. A valuable method to increase energy efficiency is to recuperate and consenquently utilize the regenerative braking energy of electric railway vehicles. The system that stores and reuses the braking energy is called a regenerative braking system, consisting of an energy storage system (ESS), a birdirectional power converter, and a control system, which includes an algorithm controlling the braking energy flow. A properly designed algorithm increases energy efficiency, lessens the stress on the power grid, increases the lifetime of the energy storage system, and enables a catenary-free operation of the electric railway vehicle. The algorithm is defined by combining two algorithms with opposite features – maximum energy savings and minimal number of cycles. The algorithm is then synthesized from those two criteria using an optimization process and then simulated while its effect on energy savings and grid stability is analyzed. Energy savings and a more stable grid are achieved with the use of the algorithm, which corroborates the inclusion of a regenerative braking system in electric railway vehicles

Common Characteristics of Power Conversion Circuits - Topology, Function and Power Semiconductor Switches

Experience in teaching of power electronics courses shows that at the beginning of the study students do not understand the common background of power conversion circuits. Students think that the topology of a converter circuit exclusively determines its function. In addition, they are not clear about the criteria by which semiconductor switches are to be selected for the given topology and type of conversion. This paper explains the approach to clarify the links between the topology and functions of the converter circuit as well as selection method for the required semiconductor switches. By using a simulation program, which contains model of the ideal switch, it is demonstrated that for the same topology, for example a single-phase bridge circuit, all four types of conversion can be realized. The selection methods of the actual semiconductor switches are based on simulation and analytical approach. By applying the proposed approach of clarifying the links between topology and function of the converter circuit, as well as applying the proposed methods for selection of semiconductor switches, the student\u27s ability to grasp the basic power electronics concepts faster and more effectively is enhanced

Route Profile Dependent Tram Regenerative Braking Algorithm with Reduced Impact on the Supply Network

Electric trams are one of the standard forms of public transport. They are characterized by large amounts of electric current and electric current gradient from the power grid, especially during acceleration. For this reason, a regenerative braking system is considered with the aim of reducing electric current peaks and increasing energy efficiency by reducing the total energy consumption of the power grid. A supercapacitor module is used as a storage device for storing and utilizing the braking energy. The supercapacitor module and the power grid constitute a hybrid energy system, for which a control algorithm has been developed. The control algorithm takes into account the influence of the elevation profile and the slope of the vehicle route in storing and using the braking energy. The operation of the algorithm was simulated and analyzed using the MATLAB/Simulink software package for tram lines with different elevation profiles

Estimating the State of Charge of Lithium-Ion Batteries Based on the Transfer Function of the Voltage Response to the Current Pulse

There are several methods for estimating the SoC of lithium-ion batteries that use electrochemical battery models or artificial intelligence and intelligent algorithms. These methods have numerous advantages but are complex and computationally intensive. This paper presents a new method for estimating the SoC of lithium-ion batteries based on identifying the transfer function of the measured battery voltage response to the charging current pulse. It is assumed that the transfer function of the battery changes with the state of charge. In the learning phase, a reference table of known SoCs and associated transfer functions is created. The parameters of these transfer functions form the reference points in hyperspace. In the phase of determining the unknown SoC of the battery, the parameters of the measured transfer function form a point in hyperspace that is compared with the reference points of the transfer functions for known SoCs. The unknown SoC of the battery at the particular measurement time is obtained by finding the two reference points closest to the point of unknown SoC using the Euclidean distance and a linear interpolation based on this distance. The method is simple, computationally undemanding, insensitive to measurement noise, and has high accuracy in SoC estimation