Simulation Of Power Electronic Systems Research Articles

Algorithms for the Accounting of Multiple Switching Events in Digital Simulation of Power-Electronic Systems

Algorithms for the Accounting of Multiple Switching Events in Digital Simulation of Power-Electronic Systems

Algorithms for the Accounting of Multiple Switching Events in Digital Simulation of Power-Electronic Systems

Digital simulation of power systems containing power electronics apparatus is challenging due to the need to account multiple switching events within one simulation time-step. This paper describes a family of algorithms, with varying levels of computational complexity, for accounting such switching events in digital simulations. The proposed algorithms are applicable for both off-line and real-time simulations. A comparative study on their performance such as harmonic content, errors in fundamental component and simulation time requirement is presented. A Pulse Width Modulated (PWM) Voltage Source Converter (VSC) based D-STATCOM system is used as a case study for simulations. Simulation results indicate excellent performance (accuracy and efficiency) in comparison with a fixed time-step algorithm using a small step-size.

Design of a Real-Time Digital Simulator for a D-STATCOM System

Real-time digital simulation of power electronic systems requires significant computational resources due to increasingly complex system configurations, control algorithms, and higher switching frequency. Consequently, it is prudent to exploit various computer resources for optimizing the design of simulators/controllers for such systems. This paper presents the design and implementation details of a real-time digital simulator for a Voltage-Source-Converter-based Distribution STATic COMpensator (D-STATCOM) power system. The design process adopts a modular approach utilizing distributed digital signal processor/field-programmable gate array resources of a digital processing platform. The design has been validated by using an experimental setup of a 5-kVA D-STATCOM system.

Advanced control methods for power electronics systems

The application of modeling methods suitable for control and simulation of power electronic systems is outlined as a self-contained approach to solve the simulation and control problems of novel structures of power electronics converters. The straightforward non-linear modeling for controller design and simulation uses switched state–space models avoiding the averaging task, needs few linear control concepts, derives the stability study from geometric properties and leads to an integrated design of the control, modulators and simulation tasks. On-line sliding mode control techniques are well suited to power converters as they are inherently variable structure systems. Obtained controllers are robust concerning converter parameter variations, semiconductor non-ideal characteristics, load and line disturbances. Main modeling and design steps are summarized and some examples given. Results show fast dynamics, no steady-state errors and robustness against semiconductor non-idealities and dead times.

Developing an advanced PWM-switch model including semiconductor device non-linearities

The accurate simulation of power electronic systems is possible when including accurate models of the semiconductor devices, but practically not affordable. Classical ideal averaged models of the system are not suitable either. Hence, averaged models including the non-linear effects of the power semiconductor devices appear quite efficient. The proposed non-ideal PWM-switch model is a useful method for modeling pulse width modulated converters operating in the continuous conduction mode. The main advantages of the proposed averaged model are the takes into account of the non-linear effects of power devices and the possibility to estimate the dissipated power in the different circuit devices. The proposed electrical model can be applied to bi-directional converters and allows the coupling with thermal model in the power electronic system. A simple technique to evaluate the different static and dynamic parameters of the devices, from manufacturers data sheets or experimentally, is presented.

A three-dimensional TLM simulation method for thermal effect in high power insulated gate bipolar transistors

The miniaturisation of electronic networks creates problems of heat dissipation. Good thermal management is therefore essential. Simulation of power electronic systems presents peculiar challenges due to the need of detailed modelling for both circuitry and control algorithms. Transmission Line Matrix method (TLM) is a powerful tool for analysing thermal effects in electronic circuits and high power devices. In this paper, thermal analysis for a 1200 A, 3.3 kV IGBT (Insulated Gate Bipolar Transistor) module has been announced at two levels, module and system level. For the module level analysis, the thermal of the IGBT module was investigated and analysed using the Three-Dimensional Transmission Line Matrix (3D-TLM) method. The results show a three-dimensional visualisation of self-heating phenomena in the device, including the effect of the use the Metal Matrix Composite (MMC) materials as base plate over conventional materials for electronic packaging thermal control and the use of the ceramics as substrate. This paper reviews the present status of the use of various thermal heat spreader such as Al SiC MMC, Cu–Mo and Graphite–Cu MMC and comparing those with copper-based heat spreader and the use of AlN, Diamond and Beo as substrates and their effect to dissipate the heat flux in heat sources localised in IGBT module design and taking into account effects of the geometry of the module, and specific material thickness because they play an important role in dissipating the generated heat and outweigh the thermal properties of the module. For the system level analysis, the total system that consists of the IGBT module and water-cooled heat sink is analysed suited to the modelling of many power electronics devices. The thermal simulations were run for various conditions and power levels including measurement and numerical results obtained by other simulators tools as MSC.PATRAN, FLOTHERM and LAASTHERM. Results are compared. The TLM method is found to be a versatile tool which is ideally suited to the modelling of many power electronic devices and proved very useful in the study of transient thermal effects in a variety of device structures.

Fast, accurate and stable simulation of power electronic systems using virtual resistors and capacitors

Simulation of power electronic circuits remains a problem due to the high level of stiffness brought about by the modelling of switches as biresistors i.e. very low turn-on resistance and very high turn-off resistance. The merits and drawbacks of two modelling methods that address this problem are discussed. A modelling solution for ensuring numerically stable, accurate and fast simulation of power electronic systems is proposed. The solution enables easy connectivity between power electronic elements in the simulation model. It involves the modelling of virtual capacitance at switching nodes to soften voltage discontinuity due to the switch current suddenly going to zero. Undesirable ringing effects that may arise due to the interaction between the virtual capacitance and circuit inductance are eliminated by modelling virtual damping resistors in parallel to inductors that are adjacent to switching elements. A midpoint configuration method is also introduced for modelling shunt capacitors. A DC traction system is simulated using this modelling strategy and the results are included. Simulation results obtained using this modelling strategy are validated by comparison with the established mesh analysis technique of modelling. The simulation performance is also compared with the Power System Blockset commercial software.

Simulation of magnetic component models in electric circuits including dynamic thermal effects

It is essential in the simulation of power electronics applications to model magnetic components accurately. In addition to modeling the nonlinear hysteresis behavior, eddy currents and winding losses must be included to provide a realistic model. In practice the losses in magnetic components give rise to significant temperature increases which can lead to major changes in the component behavior. In this paper a model of magnetic components is presented which integrates a nonlinear model of hysteresis, electro-magnetic windings and thermal behavior in a single model for use in circuit simulation of power electronics systems. Measurements and simulations are presented which demonstrate the accuracy of the approach for the electrical, magnetic and thermal domains across a variety of operating conditions, including static thermal conditions and dynamic self heating.

Choosing a thermal model for electrothermal simulation of power semiconductor devices

The literature proposes some thermal models needed for the electrothermal simulation of power electronic systems. This paper gives a useful analysis about the choice of the thermal model circuit networks, equivalent to a discretization of the heat equation by the finite difference method (FDM) and the finite-element method (FEM), and an analytic model developed by applying an internal approximation of the heat diffusion problem. The effect of the boundary condition representation and the introduced errors on temperature response at the heat source are studied. This study is advantageous, particularly for large surges of a short time duration.

Electro-thermal simulation of power electronic systems

A methodology for the development of physics-based models of power semiconductor devices is presented. The separation of the device behaviour in its basic physical elements is the basis for the establishment of an electrical model. Semiconductor parameters are strongly dependent on temperature. A close reproduction of the device performance therefore requires the determination of an equivalent circuit of the silicon chip and its package. The electrical and the thermal model parts are combined, taking the interaction between both into account consistently. The electrical and thermal model parameters are extracted from measurements.

Fast time-domain simulation by waveform relaxation methods

Fast time-domain simulation of power electronic systems by using waveform-relaxation methods is presented. Algorithms for circuit partitioning, time windowing, and simulation scheduling are developed. Practical implementation of the partitioning algorithm based on modal analysis is also discussed. Feasibility and advantages of applying these methods to power electronic systems are demonstrated by simulation results for a series resonant converter and a boost zero-voltage-transition PWM converter.

A new algorithm for simulation of power electronic systems using piecewise-linear device models

This paper describes a new algorithm for simulation of power electronic systems. Piecewise-linear (PWL) approximation is used to model nonlinear components, including switching devices, nonlinear reactive components, and nonlinear control circuitry. A representation of PWL elements is constructed such that a constant system matrix is obtained, regardless of the states of PWL elements. An efficient method for state determination is proposed, which is capable of resolving difficulties caused by discontinuous characteristics of PWL elements. The resulting simulation algorithm is quite general, requires no prior knowledge of the circuit operation, is void of convergence problems, and yields relatively short simulation times on desktop PC machines. >

An algorithm for transient simulation of power electronics systems

The development of a general algorithm, which constructs the state equations of switching systems as a function of the state of their switching elements, is presented. Although the algorithm is developed primarily for transient simulation of power electronics systems, it can be applied to any system that can be modeled by an equivalent circuit consisting of linear ERLC elements and ideal switches.