Models Of Power Electronic Converters Research Articles

FPGA-Based Hardware-in-the-Loop (HIL) Emulation of Power Electronics Circuit Using Device-Level Behavioral Modeling

Accurate models of power electronic converters can greatly enhance the accuracy of hardware-in-the-loop (HIL) simulators. This can result in faster and more cost-effective design cycles in industrial applications. This paper presents a detailed hardware model of the IGBT and power diode at the device level suggested for emulating power electronic converters on a field programmable gate array (FPGA). The static visualization of the IGBT component involves an arrangement of equivalent models for both the MOSFET and bipolar transistor in a cascading configuration. The dynamic aspect is represented by inter-electrode nonlinear capacitances. In an effort to expedite the development process while still producing reliable results, the algorithm for the simulation system was built utilizing FPGA-based rapid prototyping via the HDL Coder in MATLAB software (R2019b). Essentially, the HDL Coder transforms the Simulink blocks of these devices within MATLAB into a hardware description language (HDL) suitable for implementation on an FPGA. To evaluate the suggested IGBT hardware model and the nonlinear circuit simulation technique, a chopper circuit is replicated, and an FPGA-in-the-loop simulation is carried out to compare the efficacy and accuracy of the model with both offline simulation results and real-time simulation results using MATLAB Simulink software and the Altera FPGA Cyclone IV GX development board.

Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems

In response to national and international carbon reduction goals, renewable energy resources like photovoltaics (PV) and wind, and energy storage technologies like fuel-cells are being extensively integrated in electric grids. All these energy resources require power electronic converters (PECs) to interconnect to the electric grid. These PECs have different response characteristics to dynamic stability issues compared to conventional synchronous generators. As a result, the demand for validated models to study and control these stability issues of PECs has increased drastically. This paper provides a review of the existing PEC model types and their applicable uses. The paper provides a description of the suitable model types based on the relevant dynamic stability issues. Challenges and benefits of using the appropriate PEC model type for studying each type of stability issue are also presented.

Reliability Modeling of Multistate Degraded Power Electronic Converters With Simultaneous Exposure to Dependent Competing Failure Processes

Depending on the application in which power electronic converters (PECs) are deployed, failure processes may endanger the desirable performance of PECs. This paper offers holistic insights on reliability modeling of PECs considering dependencies in two simultaneous failure processes, namely gradual wearing-out degradation and vibration sudden degradation. While sudden and gradual degradation processes may individually affect the useful lifetime of PECs, their mutual interdependencies could significantly accelerate the aging mechanisms. A new analytical model for reliability assessment of PECs is proposed that can capture such mutual interdependence of simultaneous failure processes. The proposed analytics are applied to a DC-DC boost converter in a hybrid electric vehicle exposed to both gradual wearing-out and vibration sudden degradations. Monte Carlo-aided numerical results will demonstrate how critical it is to take into account the mutual interdependence in the failure processes when assessing the reliability performance of PECs, failure to do which may lead to inaccurate useful lifetime estimations and the corresponding maintenance and replacement decisions.

Modeling and Analysis of the Fractional-Order Flyback Converter in Continuous Conduction Mode by Caputo Fractional Calculus

In order to obtain more realistic characteristics of the converter, a fractional-order inductor and capacitor are used in the modeling of power electronic converters. However, few researches focus on power electronic converters with a fractional-order mutual inductance. This paper introduces a fractional-order flyback converter with a fractional-order mutual inductance and a fractional-order capacitor. The equivalent circuit model of the fractional-order mutual inductance is derived. Then, the state-space average model of the fractional-order flyback converter in continuous conduction mode (CCM) are established. Moreover, direct current (DC) analysis and alternating current (AC) analysis are performed under the Caputo fractional definition. Theoretical analysis shows that the orders have an important influence on the ripple, the CCM operating condition and transfer functions. Finally, the results of circuit simulation and numerical calculation are compared to verify the correctness of the theoretical analysis and the validity of the model. The simulation results show that the fractional-order flyback converter exhibits smaller overshoot, shorter setting time and higher design freedom compared with the integer-order flyback converter.

Comparative Study of Dynamic Phasor and Harmonic State-Space Modeling for Small-Signal Stability Analysis

This paper conducts a comparison of two promising frequency-lifted representations used in the state-space modeling of power-electronic converters: dynamic phasors and harmonic state-space. These methods originate from similar hypotheses and aim to tackle the time-periodicity problem observed in systems with multiple harmonic components in steady state. The paper derives the theoretical foundations of the methods with an emphasis on their similarities and differences, and applies them to a two-level voltage-source converter. The application demonstrates the effects of different truncation orders of the models infinite formulations. Stability analysis tools such as eigenvalues and transfer functions are examined and benchmarked against a classical dq-frame small-signal model.

Decentralized Frequency Control of Battery Energy Storage Systems Distributed in Isolated Microgrid

The penetration and integration of renewable energy sources into modern power systems has been increasing over recent years. This can lead to frequency excursion and low inertia due to renewable energy sources’ intermittency and absence of rotational synchronous machines. Battery energy storage systems can play a crucial role in providing the frequency compensation because of their high ramp rate and fast response. In this paper, a decentralized frequency control system composed of three parts is proposed. The first part provides adaptive frequency droop control with its droop coefficient a function of the real-time state of charge of battery. The second part provides a fully decentralized frequency restoration. In the third part, a virtual inertia emulation improves the microgrid resilience. The presented results demonstrate that the proposed control system improves the microgrid resilience and mitigates the frequency deviation when compared with conventional ω -P droop control and existing control systems. The proposed control system is verified on Real-Time Digital Simulator (RTDS), with accurate microgrid model, nonlinear battery models and detailed switching models of power electronic converters.

Hybrid Parametric Average-Value/Detailed Modeling of Line-Commutated Rectifiers

Simulations and analysis of power-electronic-based systems are conventionally done using detailed switching models of power-electronic converters that are available in many electromagnetic transient (EMT) simulation programs. Although being accurate, such detailed models typically require small time-steps for accurate detection and handling of switching events, which makes them computationally expensive. Recently, a parametric average-value modeling (PAVM) approach has been developed for system-level modeling and fast simulations of line-commutated rectifiers (LCRs) including several selected ac harmonics. In this paper, a new hybrid parametric methodology is presented, which has the capability of operating at large time-steps while including the details of the ac- and dc-side variables similar to the detailed switching models (but without the need for locating switching events, i.e., zero crossings), or operating as an average-value model. Extensive simulation studies demonstrate advantageous numerical efficiency and accuracy of the proposed hybrid parametric AVM/detailed model compared to the previous PAVMs as well as the detailed switching models of LCRs when using large time-steps for system-level studies.

Average-Value Modeling of Diode Rectifier Systems Under Asymmetrical Operation and Internal Faults

Line-commutated rectifiers (LCRs) are extensively utilized in exciters of large electrical machines, ac–dc power systems of ships, vehicles, aircraft, and many other industrial applications. Efficient and accurate computer simulations are necessary to analyze various aspects of such systems under both normal and unbalanced/faulty operating conditions. The so-called parametric average-value modeling (PAVM) technique has been recently developed and shown to provide accurate and computationally efficient models of power-electronic converters for system-level simulations. In this paper, the PAVM methodology is extended to LCRs with internal faults. The new formulation considers the asymmetrical operation of rectifiers by including the ac-side characteristic (i.e., 5th, 7th, etc.) and non-characteristic (i.e., 2nd, 3rd, 4th, etc.) harmonics in both positive and negative sequences as well as dc components that may be present on ac variables. The proposed PAVM is verified by experimental measurements and detailed model and is demonstrated to have excellent accuracy under various operating modes and fault configurations.

Real-Time Device-Level Simulation of MMC-Based MVDC Traction Power System on MPSoC

Real-time simulation of device-level power electronic converter models plays an essential role in traction power systems by allowing accurate prediction of device stresses to design improved control and protection schemes. This paper proposes the electrothermal behavioral power electronic models for the modular multilevel converter (MMC)-based medium voltage direct current (MVDC) traction power system based on the Wiener–Hammerstein configuration. The new configuration introduces the carrier charge prerequisite dynamic transients before device turn-ON or turn-OFF operation. The equivalent carrier charge circuit is also proposed, and the first-order delay assumption of turn-ON and turn-OFF delay time has been proven by the device datasheet. The power electronic device models are implemented in a Xilinx® Zynq® multiprocessing system-on-chip platform. By utilizing hardware and software codesign, both 25- $\mu \text{s}$ time-step system-level and 100-ns time-step device-level transients can be captured in real time within a single device. The three-phase unbalance issue has been resolved by introducing the three-phase to single-phase MMC topology. In the case study, the MMC-based MVDC traction power system has been utilized for the performance of the proposed electrothermal behavioral power electronic models by the off-line simulation models on SaberRD® for device-level transients and PSCAD/EMTDC® for system-level transients.

On the Equivalence and Impact on Stability of Impedance Modeling of Power Electronic Converters in Different Domains

Small-signal analysis of power electronic converters and systems is often carried out by impedance-based methods. At the core of these methods lies the impedance modeling, which can either be obtained through analytical calculations, simulations, or measurements. The impedance models can be obtained into two main domains: the dq -domain and the sequence domain. In the dq -domain, the impedance model is a $2\times 2$ matrix, while in the sequence domain, it is composed by the positive and negative sequence impedance. Recently, a third domain called the modified sequence domain was defined as an extension to the sequence domain, but also with clear similarities to the dq -domain. The objective of this paper is to unambiguously relate to each other the impedances in these three domains, and to show how this equivalence translates into their respective stability assessments. It is also proven that the sequence domain impedance has the same marginal stability condition as the dq -domain impedance matrix. The three-phase voltage source converter is used as an example converter in this paper, as its impedance model in all three domains is well established and reported by previous research. The results in this paper show that the modified sequence domain model can be derived from the dq -domain model (and vice versa), and that the stability analysis will be identical in these two domains. It is also shown how the original sequence domain model can be derived from the two other models through a model reduction. However, a small discrepancy between the two Nyquist plots is observed in the presence of components such as phase-locked loop or dc-link control.

Analytical Models Synthesis of Power Electronic Converters

In this paper we proposes a synthesis of different mathematical models of power electronic converters based on Thevenin/Norton equivalent circuits. Those models, composed by impedances and harmonic noise sources, are helpful to predict the conducted ElectroMagnetic Interferences (EMI) generated by converters connected to the electrical network. Moreover, the extracted impedances are determining for sizing EMC filters. The proposed analytical model is tested with PSpice simulations and validated by experimental measurements, from DC frequency until 30MHz.

Implementation of Rapid Prototyping Tools for Power Loss and Cost Minimization of DC-DC Converters

In this paper, power loss and cost models of power electronic converters based on converter ratings and datasheet information are presented. These models aid in creating rapid prototypes which facilitate the component selection process. Through rapid prototyping, users can estimate power loss and cost which are essential in design decisions. The proposed approach treats main power electronic components of a converter as building blocks that can be arranged to obtain multiple topologies to facilitate rapid prototyping. In order to get system-level power loss and cost models, two processes are implemented. The first process automatically provides minimum power loss or cost estimates and identifies components for specific applications and ratings; the second process estimates power losses and costs of each component of interest as well as the whole system. Two examples are used to illustrate the proposed approaches—boost and buck converters in continuous conduction mode. Achieved cost and loss estimates are over 93% accurate when compared to measured losses and real cost data. This research presents derivations of the proposed models, experimental validation of the models and demonstration of a user friendly interface that integrates all the models. Tools presented in this paper are expected to be very useful for practicing engineers, designers, and researchers, and are flexible and adaptable with changing or new technologies and varying component prices.

An induction machine and power electronic test system on a field-programmable gate array

This paper presents a field-programmable gate array (FPGA) test system composed of an induction machine, configurable as a doubly-fed induction machine or squirrel-cage induction machine, with power electronic converter models suitable for virtual motor drive control development and testing. The IM model is designed so that all parameters can be modified online without stopping the simulation. The power electronic part is customizable using a variable topology FPGA solver called Electric Hardware Solver (eHS). Permanent magnet synchronous machine and switched reluctance motor drive FPGA models are also discussed. The system is designed for fast design iteration process by allowing circuit and parameter modification using a unique bitstream. The system allows control engineers to validate production controllers in real-time, using virtual motor drives. The paper also briefly explains permanent magnet synchronous motor drives and switched reluctance motor drive implementations on FPGA.

Modelling of Power Converters Using Z-Transform

The paper introduces a novel method of analysis and modelling of power electronic converters. Z-transform, numerical series (sequences) are used for both steady and transient states investigation of converters. The new impulse switching functions are created which are used as exciting functions of one- and multidimensional state-space models. Theoretical waveforms are compared with simulation results.

Energy Space Modeling of Power Electronics in Local Area Power Networks

Power electronics are a core enabling technology for local area power networks and microgrids for renewable energy, telecom, data centers, and many other applications. Unfortunately, the modeling, simulation, and control of power electronics in these systems are complicated when using traditional converter models in conjunction with the network nodal equations. This work proposes a change of variables for the power electronic converter models from traditional voltage and currents to input conductance and stored energy. From this change of state, a universal point of load converter model can be utilized in the network nodal equations irrespective of the topology of the converter. The only impact the original converter topology has on the new model is the bounds on the control and state variables, and the mapping back to the switching or duty cycle controls. The proposed approach greatly simplifies the modeling of local area power networks and microgrids. This simpler model can be used to study stability and energy utilization and develop high-level control strategies that were not previously feasible.

Towards a Practical Identification of a DFIG Based Wind Generator Model for Grid Assessment

The main impacts on electrical systems, for transmission operators, are variations of the voltage and changes of the power flows. In this paper we detail how we have identified the main characteristics of a DFIG based wind generator. Simulation results of this model will be compared with experimental results measured on the real 1.5 MW wind generator. Thanks to the use of power electronic converters this variable speed wind generator is controlled according to four operating modes. A modeling of power electronic converters has been developed to highlight the impact of the switching phenomena and the power quality of the generated quantities.

Aircraft Power System Stability Study Including Effect of Voltage Control and Actuators Dynamic

This paper describes a stability analysis of aircraft ac frequency-wild power systems with constant power loads (CPL). In contrast to previous publications, the proposed analysis method employs the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$dq$</tex> modeling approach instead of the state-space averaging (SSA) and average-value modeling (AVM) methods to derive power-electronic converter models for stability studies. This results in lower order models and allows the modeling of vector-controlled converter elements where the SSA and AVM methods are not easily applicable. The resulting model can be combined with models of other power system elements expressed in terms of synchronously rotating frames (generators, front-end converters, vector-controlled drives, etc.). The paper analyzes the stability of frequency-wild power systems for both load and parameter variations and takes into account controlled generator voltage dynamics and electromechanical actuator dynamics. The stability margins are assessed and compared with those for power systems with the ideal voltage source and the ideal CPLs. The study is supported by intensive time domain simulations that support the theory.

MATLAB-Based Modeling to Study the Effects of Partial Shading on PV Array Characteristics

The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.

Two time scale global dynamical modelling of power electronic systems

Global dynamical models of power electronic systems allow to compute their dynamics in a very easy way as they replace the switching behavior of the power electronic converter by a continuous process [F. Labrique, H. Buyse, G. Seguier, R. Bausiere, Les convertisseurs de l’electronique de puissance—Commande et comportement dynamique, vol. 5, Technique et Documentation, Lavoisier, Paris, France, 1998; H. Buyse, D. Grenier, F. Labrique, S. Gusia, Dynamic modelling of power electronic converters using a describing function like approach, in: Proceedings of the ELECTRIMACS’99 Conference, vol. 1, Lisbon, Portugal, 1999, pp. 7–14]. But they are unable to predict the ripples induced by the switching behavior of the power semiconductor switches. The aim of this paper is to show for power electronic systems using a power electronic converter working in a PWM mode, how it is possible to define a global dynamical model including a dynamical model of the ripple effects.

Teaching nonlinear modeling, simulation, and control of electronic power converters using MATLAB/SIMULINK

This paper describes an efficient method to teach analysis and simulation of power electronic converters to undergraduate students, using system level nonlinear state-space models. System-level modeling of power electronic converters reproduces only the ideal switching behavior of the semiconductors and is a useful concept for the numerical simulation of power converters, since simulations present no convergence problems and require little computational time. Switched state-space models, programmed in the MATLAB/SIMULINK software package, can be advantageously used to simulate power converters at the system level and also to design and study their controllers. Switched state-space nonlinear models should be obtained using a theoretical framework suitable for the enhanced control of variable structure power systems. Since the method is inherently nonlinear, no approximated linear models are needed; and since state-space models are used, modern control techniques (sliding mode, neural networks, fuzzy logic) for power converters can easily be used. This paper summarizes the proposed methodology and gives some examples.