Reliability Of Converter Research Articles

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ КОНТРОЛЕРА ДЛЯ КЕРУВАННЯ ТЯГОВИМ ЕЛЕКРОДВИГУНОМ НА ПОСТІЙНИХ МАГНІТАХ

The controller of traction electric motors on permanent magnets for vehicles in which the power transistor converter is made on the modified IGBT modules with the improved characteristics is described in this work. The use of these modules, which are widely used today in semiconductor devices of modern dual-use technology, allows to reduce the size and weight of the converter, simplify the cooling system, increase efficiency and reliability of the semiconductor converter and electric drive in general due to harsh operating conditions. Bench tests of the experimental sample of the semiconductor converter and the microprocessor control system in various operating modes, including at the maximum load corresponding to real operating conditions are made and carried out. As a result of tests, it was determined that the technical characteristics of the controller meet the requirements of such devices. The created semiconductor controller on IGBT modified modules can be used to control motors on permanent magnets and motor wheels with a nominal power of 40-50 kW, maximum - 100 kW. References 11, figures 8, tables 4.

Full-Bridge Submodule Development of an MMC-Like Topology for ASDEX Upgrade Toroidal Field Coils Power Supply

The modular multilevel converter (MMC) has become one of the most attractive converters for high-power applications such as high-voltage dc (HVDC) converters, but also fusion devices’ power supplies. This converter, thanks to the discrete-leveled output voltage and its identical submodules (SMs) by which it is composed, represents a promising alternative to replace the flywheel generator (FG) that actually provides electrical power to Axially Symmetric Divertor Experiment (ASDEX) Upgrade device’s toroidal field (TF) coils. Due to the pulsed dc operation of these coils and their high-power needs (up to 150 MW) for each experiment, a small-scale version of MMC is under development with some differences compared with conventional ones: SM’s capacitors have been replaced with supercapacitor (SC) modules to increase the amount of available stored energy, while SMs belonging to different “rows” are interconnected to simplify their control and increase the reliability of the converter. This article shows the development and the operation of a single IGBT full-bridge (FB) SM highlighting advantages of this configuration and challenges of a full-scale converter: a proper power stage filter has been designed to protect SCs from voltage spikes and high-frequency current content generated during IGBT switching events, while SM’s control has been realized, thanks to the EtherCAT protocol, which ensures synchronization in case of SMs’ parallel operation and reliability of the future full-scale converter.

Common-Mode Current Analysis and Cancellation Technique for Dual Active Bridge Converter Based DC System

This article presents an active neutral point clamped (ANPC)-based parallel dual-active bridge (DAB) architecture which combines <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> cancellation and power sharing in order to reduce electromagnetic interference (EMI) caused by common-mode (CM) current. High <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> associated with wide bandgap devices causes high CM current mainly due to parasitic capacitances. The corresponding conducted EMI can remarkably reduce the reliability of power converters and other onboard systems. This issue becomes worse due to higher dc bus voltage trend in electric vehicles (EV) and other dc systems. Conventional techniques struggle to provide attenuation in a wide frequency range. The problem can also be severe in soft-switched DAB converters as they operate at relatively higher frequencies. In this article, initially, an in-depth theoretical analysis is provided to understand the complimentary <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> events. Various factors causing nonideal <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> cancellation are discussed in detail together with possible solutions. Detailed experimental results are obtained from a 1100 V–150 V parallel DAB system including both the high and low voltage sides at different <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> rates. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> cancellation at lowered <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> rates facilitated by power sharing and small snubbers provide up to 25 dBuA reduction in CM conducted EMI. A comparison with CM chokes is also presented to validate improved attenuation in a wide frequency range.

Enhancing reliability of photovoltaic power electronic converters under dynamic irradiance conditions

This paper presents a novel temperature-controlled maximum power point tracking (MPPT) algorithm for lifetime improvement of a photovoltaic (PV) converter under dynamic irradiance conditions. The proposed algorithm controls and limits the junction temperature change rate of switching devices, reducing the thermal stress and drastically reducing the damage received, hence improving the reliability and lifetime of power converters in PV systems. To evaluate the damage reduction, a lifetime estimation technique is applied which is composed of a Foster thermal model, a rainflow counting algorithm and an empirical lifetime model. Moreover, in this paper the energy and life consumption are calculated with the application of lookup tables to reduce computation time. The effectiveness of the proposed algorithm is verified using extensive simulations and by comparing energy generated and life consumption under irradiance profiles for different cloud conditions. The temperature-controlled algorithm is applied in parallel with a normal MPPT algorithm to a 10 kW photovoltaic system and results are compared using irradiance data from the province of Quebec, Canada to validate its efficacy. The obtained results show that for very variable cloud conditions, the modified algorithm managed to reduce the life consumption by 4.68 % at no extra cost, with just 0.08 % of energy generation reduction, proving its effectiveness.

Mathematical Modeling of the Reliability of Ferromagnetic Current Converters with Adjustable Range for Traction Power Supply Devices

The factors affecting the operational reliability of primary measuring transducers (PMT) developed on the basis of ferromagnetic current transducers with adjustable range (FMCT RD) are highlighted. An assessment and analysis of the system of basic quantitative indicators of reliability for each of the proposed three current converters, which differ in the principles of operation and the number of assembly units, is made. A maintenance and repair strategy is indicated, combined with the use of methods and tools of a modern diagnostic system that ensures the reliability of these converters, using a combination of three groups of stages: during design, during their operation and repair.

Mathematical Modeling of the Reliability of Ferromagnetic Current Converters with Adjustable Range for Traction Power Supply Devices

Mathematical Modeling of the Reliability of Ferromagnetic Current Converters with Adjustable Range for Traction Power Supply Devices

A Temperature-Dependent Cauer Model Simulation of IGBT Module With Analytical Thermal Impedance Characterization

In pursuit of high power density and high reliability of power converters, the junction temperature of power devices becomes an essential indicator for heath condition monitoring and thermal management. Particularly under high-temperature operating conditions, the temperature-dependent thermal properties of the chip and ceramic materials must be incorporated to enhance the prediction accuracy. In this article, an improved temperature-dependent Cauer-type thermal network of insulated-gate bipolar transistor (IGBT) module is established. The temperature dependence of thermal parameters for the chip layer and ceramic layer is meticulously considered. More importantly, finite-element method (FEM) simulation is used to yield the heat flux curve of the power module at the center line in order to better imitate the real heat-spreading scenario. In this way, the effective heat transfer area of each layer can be calculated accurately and analytically. By this analytic method, the temperature-dependent thermal impedance can be efficiently determined. Compared with prior-art fully FEM-based temperature-dependent thermal impedance characterization method, the method proposed in this article reduces the FEM simulation time cost approximately 20 times under the same computing hardware facilities and considerably simplifies the parameter extraction process. Finally, experimental results based on two commercial IGBT modules successfully validate the usefulness, effectiveness, and accuracy of the proposed thermal network model.

Non-Isolated DC-DC Converters in Fuel Cell Applications: Thermal Analysis and Reliability Comparison

An alternative energy source that has appeared beyond expectations and has seen a lot of progress is the fuel cell. A proton exchange membrane (PEM) fuel cell is chosen for analysis and requires a DC-DC boost converter as an interface between the fuel cell and the load to provide a high-gain regulated voltage. Although great effort towards developing different converter topologies has been made during recent decades, less attention has been devoted to the reliability and thermal performance assessment of the present converters. In this paper, five non-isolated DC-DC converters are analyzed in terms of both thermal behavior and reliability. The temperature estimation of semiconductor devices as a critical part of the thermal analysis has been made via a detailed thermal model and the reliability is evaluated by means of a power cycling test. Finally, a performance score has been attributed using the TOPSIS ranking methodology and considering all the criteria (e.g., the number of components and cost) at the same time. The results indicated that the floating interleaved boost converter is always at the top of the list, even if the weight of the indicators is changed. When the weight of the cost criterion is higher than the reliability criterion, the multi-switch boost converter will be in second place. If the weight of the reliability criterion is greater than cost, the interleaved and multi-switch converter are ranked second and third, respectively. Additionally, the Cuk converter with a closeness coefficient of zero is always associated with the most unfavorable performance.

Analysis of Power Loss in Forward Converter Transformer Using a Novel Machine Learning Based Optimization Framework

High power and high voltage gains in Forward Converter significance are a foremost topic for wind power switch mode supplies. However, due to the recent penetration of forward converter usage in the power network and wide range of load, the reliability and power loss problem becomes a crucial one. Therefore, this paper projected a novel Grey Wolf based Boosting Intelligent Frame (GWbBIF) control algorithm for improving the reliability of power system since the incorporation of forward converter to the entire system level. Consequently, the power loss of transformer is optimized by the projected Grey Wolf fitness function. The implementation of this work has been done on MATLAB/Simulink. The simulation outcomes of the proposed system show that the forward converter reliability and power loss of transformer are considered as significant aspects while estimating the whole system function. The proposed outcomes are compared with the conventional methods for validating the importance of the projected method.

Performance Comparison of Optimization Algorithm Tuned PID Controllers in Positive Output Re-Lift Luo Converter Operation for Electric Vehicle Applications

In this work, a Particle Swarm-Based optimization algorithm is proposed to optimize the PID controller used in the Positive Output Re-Lift Luo converter for the Electric Vehicle application. The novelty of the work lies in developing an improved PID controller to explore the reliability of the re-lift Luo converter. In addition, the optimization improves the effectiveness of the closed-loop system that possesses high voltage gain with esteemed power density and efficiency. With the Particle Swarm Optimization control algorithm, , , and values are tuned in such a way to obtain the appropriate steady-state condition with no peak overshoot or undershoot, much lesser settling time, no steady-state error, and improved dynamic performances. To analyze the system stability and to obtain better results, reduced-order state-space modeling of the Re-lift Luo converter is adopted, which offers high computational speed and accuracy. Initially, a PID controller is designed using the Zeigler Nicholas method, and the results are compared with the genetic algorithm and Particle Swarm Optimization algorithm. The time-domain analysis has been carried out to analyze and compare the converter’s performance. The simulation results were verified experimentally, and the results prove the robustness of the proposed converter with a PID controller optimized using the Particle Swarm Optimization algorithm.

Reliability evaluation of an aggregate power conversion unit in the off-grid PV-battery-based DC microgrid from local energy communities under dynamic and transient operation

In a rural/local energy community (LEC), a PV-battery-based DC microgrid (MG) normally operates at the off-grid/islanded mode. At this off-grid operation mode, the reliability of power converters in both the PV system and the battery energy storage system (BESS) could be reduced by dynamic operation scenarios of the DC microgrid which are frequently repeated, such as the intermittency of PV-system output power, the random fluctuation of load power. Indeed, the dynamic operation of the PV-generating system and the load system in the off-grid DC microgrid could lead to a certain decrease in the reliability of DC–DC bidirectional converters of the BESS, boost converters of the PV system, and buck converters for low-voltage DC loads because of withstanding different power flows to provide a source-load power balance in the DC microgrid. Moreover, transient operation scenarios of the off-grid DC microgrid can significantly impact the reliability of the mentioned power converters. To make the above assumptions more clear, reliability analysis of an aggregate power conversion unit (APCU) in the off-grid PV-battery-based DC microgrid under dynamic and transient operation in the local energy community is presented in this paper. The APCU contains the boost converter of the PV system, the bidirectional converter of the BESS, and the buck converter of the low-voltage DC load system. The main objective of the paper is to shed light on calculations of the dynamic-voltage-dependent failure rate (DVDFR) and fault-current-dependent failure rate (FCDFR) of the APCU from dynamic and transient operation conditions respectively in the off-grid LVDC microgrid. Then, a novel combination of the useful-time-dependent failure rate (UTDFR), the DVDFR, and the FCDFR is proposed to evaluate the system-level and component-level reliability of the APCU in the off-grid DC microgrid. Markov-state transition diagrams are applied for the APCU’s reliability assessment. Experimental results show that the reliability of the bidirectional power converter is more affected by the dynamic and transient operation than that of the boost or buck converters in the APCU. In addition, the DVDFR of the APCU is almost smaller than its FCDFR, but the system-level reliability of the APCU could be significantly reduced by dynamic cases in the islanded DC microgrid. Last but not least, the MTTF and MTBF of the APCU could be dramatically decreased by the dynamic and transient operation of the DC microgrid.

Electrothermal Performance-Based FCS-MPC for Dynamic Thermal Balance Control of Traction Converters

The thermal stress imbalance is a challenge for the reliability and in-service lifetime of modular multilevel converters, especially in traction drive applications. The finite-control-set model predictive control (FCS-MPC) can offer an effective solution to this issue, but it is faced with two difficulties, that is, the weight allocation of electrical and thermal variables with different natures in control objectives functions, and dynamic weighting factor adjustment during the switching of variable operations. Therefore, an electrothermal performance-based FCS-MPC (ETP-FCS-MPC) for dynamic thermal balance control is proposed, which can not only achieve thermal stress balance in converters with more intuitive and time-saving ways but also offer dynamic compromise schemes between the electrical and thermal performance of converters in the speed switching process. First of all, dynamic electrical and thermal models of converters are presented. Then, the absolute error-based electrical control objective and the energy loss variance-based thermal control objective are designed. Moreover, a performance-based normalized control objective function and an outer loop control feedback-based dynamic weighting factor are proposed. Finally, hardware-in-the-loop (HIL)-based test is carried out to verify the effectiveness of the proposed method, and the test results show the merits of the proposed method.

A New Kalman-Filter-Based Harmonic Current Suppression Method for the Virtual Oscillator Controlled Grid-Tied Inverter

Virtual Oscillator Control (VOC) is an advanced nonlinear grid-forming controller used for power electronics interfaced distributed generation (DG). In order to improve the reliability of voltage source converter connecting to the disturbance grid, a feedback method with enhanced virtual impedance had been inserted into the control loop of the VOC-based inverter to suppress grid-injected harmonic currents. In this paper, a new grid-injected harmonic current suppression strategy with estimated voltage feedforward is proposed for a VOC-based voltage source inverter (VSI) connected to the distorted electrical grid. To achieve the control target, the Kalman-Filter is adopted to estimate the harmonic components of the grid voltage at the point of common coupling (PCC) and insert them to the feedforward control loop of the VOC-based inverter. Compared with the traditional VOC with enhanced virtual impedance method, the proposed control strategy has a slightly better ability to suppress the grid-injected harmonic current. A 3 kW/3-phase/120 V experimental prototype system designed on the DSPACE DS1202 platform has been developed to verify the effectiveness of the proposed control strategy.

A non‐isolated switched inductor‐capacitor cell based multiple high voltage gain DC‐DC boost converter

AbstractIn this paper, a non‐isolated switched inductor cell integrated high step‐up voltage gain DC‐DC converter with a charge pump mechanism is discussed. The continuous conduction mode of the input current is a beneficial aspect of this converter, which is appropriate for electric vehicles, renewable energy, and LED applications. The proposed converter works in two distinct operating modes and provides a flexible range of voltage gain ratios. The performance and small‐signal modeling of the converter in continuous conduction mode are extensively investigated, and voltage gain calculations for the two operational modes are derived. The Markov technique is used to evaluate the converter reliability, component failure rates, and mean time to failures. The proposed converter is evaluated with the existing converters in terms of voltage, and current stress of each component, voltage gain, total component stress factor, component count, and reliability. The proposed converter's hardware prototype has been developed. To validate the theoretical calculations, the converter's simulation and experimental results are discussed. The converter has a maximum output voltage of 110 V and a switching frequency of 50 kHz. The converter's peak efficiency is 94.5%.

Modelling of Wind Turbine Operation for Enhanced Power Electronics Reliability

Enhancing power electronics (PE) converter reliability is crucial for ensuring a reliable operation of current and future operating Wind Turbines (WTs). Achieving high reliability of variable speed WT PE systems requires careful consideration of their operation, and particularly their thermal cycling. This paper presents a methodology for evaluating and reconsidering operational strategies of WTs with relation to the thermal loading and lifetime consumption of the converter. The methodology is applied to compare control strategies for the WT generator and evaluate their impact on the converter reliability by observation of the thermal cycles and by calculating the resultant lifetime consumption of those stress cycles. The thermal stress on both the Machine Side Converter (MSC) and the Grid Side Converter (GSC) is examined and compared. It is shown that the least reliable of the three evaluated control strategies is the one that tracks the power curve below rated speed most closely. This paper suggests that dynamic transients associated with the WT control largely influence the IGBT module wear-out and their modelling needs to be prioritized for lifetime studies. These dynamic transients are captured by the improved model whose value is confirmed for the comparisons in the case study of the paper.

Quantitative Reliability Evaluation of Silicon Carbide-Based Inverters for Multiphase Electric Drives for Electric Vehicles

Abstract Reliability of power converter in the electric drivetrain of a vehicle can be a criterion for the comparison of various converter topologies, cooling system designs and control strategies. Therefore, reliability prediction is important for the design and control of vehicles. This paper presents an approach for quantitative evaluation of the reliability of converters for multiphase motor drives for electric vehicles (EVs) after considering the driving cycle. This paper provides a good background of reliability quantification so that it is easy to extend the presented approach to other applications. The models of subsystems have been selected to have excellent computational efficiency with good accuracy which is necessary for simulating long driving cycles. A simple vehicle model is used to obtain the traction motor torque demand for various points of the driving cycle. A multiphase interior permanent magnet synchronous motor has been used for traction motor. The operating voltage and currents of the motor are found using maximum torque per ampere (MTPA) control of IPMSM. The analytical loss calculation has been used to find the losses of switching devices of the converter. A thermal model of silicon carbide (SiC) MOSFET has been used to calculate junction temperature from the losses. The model developed here gives the failure rate and mean time between failures (MTBF) of switching devices of the inverter, which can be used to determine the failure rate. The model has been used to find the transition probabilities of a Markov model which can be used to quantify the reliability of converters of multiphase electric drives.

Reliability Evaluation of Isolated Buck-Boost DC-DC Series Resonant Converter

This paper investigates the reliability of an isolated buck-boost DC-DC converter (IBBC) based on the configuration of a series resonant converter (SRC). Two approaches are employed to predict the IBBC reliability, which are based on the MIL-HDBK-217F handbook and FIDES guide. The latter approach can take into account how the failure rate of the converter components based on the physics of failure is influenced by a varying yearly mission profile. To do this, the thermal loading of each IBBC component is obtained, taking into account the photovoltaic (PV) mission profile of the solar irradiance and ambient temperature. In such a case, the PV module is operating at the maximum power point (MPP) and the IBBC transfers this power into the DC microgrid (MG). Second, the component-level failure rate is calculated with both reliability assessment approaches, to evaluate the converter-level failure rate. Therefore, the converter reliability can be defined while taking the serial reliability connection of the converter components into account. The reliability analysis is carried out using a cloud Python engine installed and running in a Google Colaboratory notebook. The results indicate that the primary semiconductors are the most vulnerable component in the IBBC. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$B_{10}$</tex-math></inline-formula> lifetime of the case-study IBBC calculated using the MIL-HDBK-217F and FIDES approaches is 14.80 and 23.20 years, respectively. This indicates that, when compared to the methodology from the MIL-HDBK-217F handbook, the approach from the FIDES guide can provide a more accurate prediction for the IBBC lifespan considering the real field mission profile.

Modeling and Suppression of the Crosstalk Issue Considering the Influence of the Parasitic Parameters of SiC MOSFETs

Due to the extremely fast switching speed of the SiC MOSFET, its crosstalk issue is more serious than that of the Si IGBT. Therefore, in order to ensure the reliability of the SiC MOSFET converters, the crosstalk problem must be solved firstly. Most of the existing crosstalk suppression methods are aimed at decreasing the crosstalk voltage introduced by the parasitic gate-drain capacitance (Miller capacitance), ignoring the influence of other parasitic parameters on the crosstalk voltage, such as the common source inductance, which may also lead to more serious reliability problems. Thus, this paper firstly establishes the mathematical model of the switching process of the SiC MOSFET half-bridge inverter. Then, the effects of various parasitic parameters (the gate-source capacitance, the gate-drain capacitance, the common source inductance, the gate inductance, the drain inductance) on the crosstalk voltage are analyzed and modeled in detail, which is verified by experiments. Based on the analyses and models, a novel crosstalk voltage suppression circuit is proposed, which can not only suppress the crosstalk caused by the gate-drain capacitance, but also solve the crosstalk issue considering the influence of other parasitic parameters, such as the common source inductance. Finally, a double pulse test platform is established to verify the effectiveness of the designed crosstalk suppression circuit under different voltage/current conditions.

Fault Prediction for Capacitor of Power Converters Based on CEEMDAN and GWO-RELM

Aluminum electrolytic capacitors (AECs) get multiple superior functions such as filtering, energy storage and decoupling, which have a great effect on the performance and lifetime for power converters. Therefore, analyzing and predicting the faults of Aluminum electrolytic capacitors (AECs) is conducive to improve the safety and reliability of the power converters. In order to establish the AECs’ fault prediction model and improve the accuracy, an integrated model based on complete ensemble empirical mode decomposition with adaptive noise, grey wolf optimization algorithm and regularized extreme learning machine (CEEMDAN-GWO-RELM) is proposed. The CEEMDAN is used to decompose the time series of AEC degradation process into several sequences, which can decouple the feature of local fluctuations from global degradation in the AEC time series. Then, the RELM optimized by GWO is used to predict each sequence after decomposition. RELM has the advantages of fewer hyperparameters and less operation time, and GWO with strong astringency is used for its optimization to obtain better fault prediction. Eventually, the predicted values are reconstructed to obtain the predicted values of the integrated model. The results show that, based on the aging data of AEC, the integrated model based on CEEMDAN-GWO-RELM can provide better prediction progress than traditional models, and the maximum relative error of each prediction time point is lower than 1.6%.

Module Lifetime Evaluation Method for the Power Converter of the DFIG Based on the Analysis of the Field Wind Speed Probability and Ambient Temperature

The junction temperature fluctuation (&#x0394;Tj) of the doubly fed induction generator (DFIG) around the synchronous speed point, deteriorates the reliability of the power converter considerably. Therefore, a lifetime evaluation method for the power converter of DFIG is proposed in this paper. Combining the speed-power curve of the generator with the grid side converter (GSC) and the rotor side converter (RSC), and using the equivalent thermo-electric network of IGBT module, the junction temperature (Tj) model of the power converter is established to calculate the average junction temperature and fundamental frequency temperature fluctuation. Based on the field measured data of the wind speed probability and ambient temperature of three wind power plants in different latitude region, the operation life curves of GSC and RSC are obtained by curve fitting, and the life spans of five type of power modules are evaluated and compared. It can be seen that the lifetime of the converter could be reduced significantly due to the ambient temperature-induced low frequency temperature fluctuations in the thermal cycling, while, the fundamental frequency thermal cycle caused by the running frequency of the converter has slight effect on the overall life.