Viktor Šunde

A temperature-dependent electrothermal MOSFET model for calculating its current loadability

A developed temperature-dependent electrothermal model consists of a temperature dependent MOSFET model and a temperature independent model of the MOSFET thermal system. The temperature dependent MOSFET parameters are the channel charge carriers mobility, drift area resistance and threshold voltage. Calculated at each moment are voltage, current, losses (including conduction losses, built-in diode losses and switching losses) and the virtual junction temperature. During the simulation, the MOSFET temperature dependent parameters depended on instantaneous virtual junction temperature. The electrothermal model is based on catalog data about MOSFET. It gives the designer highly precise information necessary for electrical and thermal design of electronic circuits, especially of electronic power converters in transient and stationary states. The temperature dependent electrothermal model was developed using an IsSpice4 software program. The existing model of the signal MOSFET was expanded with the temperature dependence of parameters and supplemented with an electrical model of its thermal system. First, the model was checked by simulating catalog characteristics and next by comparing a simulated time course for losses and for virtual junction temperature with a measured time course of losses and virtual junction temperature of the MOSFET in one chopper measuring the time course of virtual junction temperature required designing a special measuring equipment.

Estimation of Insulated-gate Bipolar Transistor Operating Temperature: Simulation and Experiment

Knowledge of a power semiconductor’s operating temperature is important in circuit design and converter control. Designing appropriate circuitry that does not affect regular circuit operation during virtual junction temperature measurement at actual operating conditions is a demanding task for engineers. The proposed method enables virtual junction temperature estimation with a dedicated modified gate driver circuit based on real-time measurement of a semiconductor’s quasi-threshold voltage. A simulation was conducted before the circuit was designed to verify the concept and to determine the basic properties and potential drawbacks of the proposed method.

Electrothermal modeling and simulation with SIMPLORER

Modern circuit simulators for power electronics have implemented electrothermal models of power semiconductors in their libraries. For successful simulation, interaction between electrical behaviour and self-heating effects cannot be neglected. SIMPLORER simulator is between the first that have implemented electrothermal models of power semiconductors at device level. In this paper validation of SIMPLORERs power MOSFET electrothermal model is performed. As a temperature sensor during measurement TEMPFET was used, resulting with good agreement of simulation and measurement results.

High Power Soft-Switching IGBT DC-DC Converter

A soft-switching topology for high power buck converter is proposed. Zero-current turn-on and zero-voltage turn-off is achieved without auxiliary switches. All active switches in the converter transmit power to the load equally. Converter control is simple despite four active switches. Converter operation is described and DC analysis is carried out. All operation modes are identified. The condition for soft-switching is derived. A full-scale 38 kW laboratory prototype with 1700 V IGBT modules is built for railway application. Switching frequency is fixed at 20 kHz. Experimental results are shown. The results confirm the analysis. A high efficiency of 97 % is achieved.

Undergraduate Power Electronics Laboratory - Applying TSMST Method

This paper presents a TSMST (Theory ? Simulation ? Measurement ? Simulation ? Theory) method for power electronics laboratory. The method successfully integrates theory, simulation and measurement, thus enabling better integration of student’s knowledge and better usage of inadequate number of laboratory hours. Students are attracted with relatively simple tasks to be solved and modern, but economical laboratory equipment. A significant part of the assignments can be made at home, thus lowering the pressure on students to finish the tasks on time. The proposed method is described on three basic examples explaining characteristic phases of the TSMST method.

Integration of Measurement and Simulation in Power Electronics Laboratory

The paper presents integrative approach for educational power electronics laboratory, where measurements and simulations are equally used in laboratory exercises. Hardware and software part of laboratory are described, with typical examples deeply explained. Te best properties of measurement and simulation are used to reach final goal ¿ better understanding of power electronic circuit behavior. Proper balance between measurement and simulation is the key for interesting and useful laboratory exercises. First results are promising, students evaluation of described laboratory is very good.

Computer in power electronics education

The paper describes different possibilities of using the computer in power electronics education. After discussing several computer application possibilities, the usage of computers in education processes at FER Zagreb is explained. Various forms of computer application are used for lectures, as well as for laboratory exercises. A multimedia approach is implemented in all forms of the teaching process. Presentation slides, animations, simulations, measurements on real circuits, as well as video clips are extensively used, resulting in a more interesting teaching process and better student knowledge.

Algorithm for fast determination of LiFePO4 battery nominal current

The development of production and increasing usage of light electric vehicles such as electric bicycles and electric scooters entails development of batteries, battery chargers and fast charging algorithms. Batteries with different nominal electrical characteristics and production technologies are currently in use. Among them, lithium-iron batteries are increasingly being used. The differences in basic characteristics of batteries and standardization issues require fast identification of various battery types and adapting of charging algorithms according to nominal current, voltage, capacity and state of charge. This paper describes a method for determining the nominal current for unknown LiFePO4 battery connected to the stationary filling station for charging electric bicycles. A prerequisite for determination of the rated current is identification of current-voltage curve at the moment of connection and identification of the number of cells. The algorithm for determining these parameters is given in the first part of the paper. The second part deals with determination of the nominal current for LiFePO4 battery based on current-voltage response to the selected battery charging algorithm.

Simple Hybrid Electrothermal Simulation Procedure

Electrothermal models of power semiconductor components are often too complex and requiring a long simulation time. Besides, there can be a situation that electrical and thermal behaviour of the circuit are not analyzed within the same department of a company. This necessitates an appropriate procedure of electrothermal simulation, sufficiently quick, accurate and simple, allowing an efficient exchange of data of electrical and thermal parts of the system. Presented in this article is a simple calculation procedure for the time course of silicon equivalent temperature in power semiconductor components, based on the previously calculated current loading. This hybrid procedure allows the exchange and use of simulation results in case of separated procedures of current and thermal dimensioning of power semiconductor components

Semiconductor loss distribution evaluation for three level ANPC converter using different modulation strategies

Active neutral point clamped (ANPC) converter was developed in order to improve the performances of the neutral point clamped (NPC) converter in terms of the semiconductor loss distribution. Loss distribution depends primarily on modulation type used for generation of the switching signals, therefore it is important to find the appropriate modulation type that will allow the most uniform loss distribution. In order to analyze the behavior of the grid connected ANPC converter a simulation model was created in Plexim blockset Plecs in Matlab/Simulink. Through simulations seven PWM modulations are analyzed for different operating modes and modulation indexes of the ANPC converter in order to find the appropriate modulation method for different operation points of the converter.