Zeljko Jakopovic

Important properties of transient thermal impedance for MOS-gated power semiconductors

Important properties of transient thermal impedance (TTI) for MOS-gated power semiconductors are investigated on the basis of measurement results. An electrical method of transient thermal impedance measurement was used with different temperature sensitive electrical parameters (TSEPs). A wide variety of measurements on MOSFET and IGBT samples was performed, to be able to answer the questions about TTI existence conditions. Different types of temperature responses were used, as well as different power dissipation levels and conditions. Finally, a TEMPFET test, with simulation and measurement of overtemperature protection reaction time, shows that TTI of MOS-gated components, if properly measured, can be successfully used for simulative estimation of a semiconductors operating temperature.

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.

High Performance Predictive Current Control for Active Shunt Filters

A discrete-time predictive current controller, for the application of active power filtering, is designed and analyzed in this paper. A modified algorithm of reference current prediction in the conditions of step change in amplitude and/or frequency is proposed. The theoretical analysis and the validity of the proposed method are verified by simulations. Comparison for the 5th and the 7th harmonic current control is made with the results achieved using synchronous PI plus lead compensator

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.

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.

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

Single phase active power filter

Single phase active power filter (APF) with sliding mode control is analyzed mathematically and by simulation. An APF is power electronics device that is connected parallel to the grid and the load, with task to cancel the reactive and harmonic currents caused by nonlinear loads connected to the grid. Proposed solution is implemented on laboratory test system with universal microprocessor control system. Behavior of realized APF is analyzed under different conditions. Limitations of used microprocessor control system for APF with sliding mode control using Matlab - Simulink are explored.