Power Electronic Circuits Research Articles

Wireless Charging of Electrical Vehicle on Road

Electric vehicles are seen as an alternative option in response to the depletion of resources. In order to increase the use of EVs in daily life, practical and reliable methods to charge batteries of EVs are quite important, accordingly wireless power transfer (WPT) is considered as a solution to charge batteries. In this project, a prototype system of wireless charger which has 60 kHz operation frequency is designed and implemented. Plug-in Electric Vehicles (PEV) are burdened by the need for cable and plug charger, galvanic isolation of the on-board electronics, bulk and cost of this charger and the large energy storage system (ESS) packs needed. But by using Wireless Charging system‘s Wireless charging opportunity. It Provides convenience to the customer, inherent electrical isolation, regulation done on grid side and reduces on-board ESS size using dynamic on-road charging. The main objective of our project is to design and develop an antenna system suitable for vehicle using resonant magnetic coupled wireless power transfer technology to electric vehicle charging systems. Application of WPT in EVs provides a clean, convenient and safe operation. At the core of the WPT systems are primary and secondary coils. These coils construct a loosely coupled system where the coupling coefficient is between 0.1-0.5. In order to transfer the rated power, both sides have to be tuned by resonant capacitors. The operating frequency is a key selection criterion for all applications and it especially affects the dimensions of the coils and the selection of the components for the power electronic circuit. A Resonant wireless transfer system for vehicle charging technology is designed.

System Identification and Control Design of a Wireless Charging Transfer System with Double-Sided LCC Converter

Increasing production of electric vehicles (EVs) and the challenge of charging these types of vehicles have been one of the most important research topics in the current century. Due to the low-battery energy density of EVs (compared to fuel) as well as the long time required to charge EVs, wireless power transfer (WPT) technology is an interesting topic researched in recent years. The WPT system in EVs can be studied in both static and dynamic scenarios. In this study, symmetrical circular couplers are first presented as system magnetic couplers and their magnetic calculations are analyzed using finite element method. Then, a new approach is proposed to design the power electronic circuits of the WPT, including a double-sided LCC compensator, and providing an approximation for calculating the ratio of output to input voltage. This method shows how to select the appropriate values of the passive elements for high system efficiency that can meet the output power and voltage. Firstly, the efficacy of the proposed approach is confirmed by experimental and simulation results. Then, using the input control of inverter MOSFETs through pulse width modulation method and proportional integral controller, the output voltage of the system is kept constant while increasing or decreasing the input voltage.

Accurate time-domain simulation of power electronic circuits✰

Modern power electronic circuits contain numerous switches driven by high frequency controllers and can cause discontinuities in time-domain simulation methods. This paper presents numerical problems resulting from discontinuities when simulating power electronic circuits. Limitations in existing methods are analyzed. Three new methods are proposed to improve accuracy and computational performance.

Paralleling insulated-gate bipolar transistors in the H-bridge structure to reduce current stress

In this study we present the new power electronic circuit implementation to create the arbitrary near-rectangular electromagnetic pulse. To this end, we develop a parallel- Insulated-gate bipolar transistors (IGBT)-based magnetic pulse generator utilizing the H-bridge architecture. This approach effectively reduces the current stress on the power switches while maintaining a simple structure using a single DC source and energy storage capacitor. Experimental results from the circuit characterization show that the proposed circuit is capable of repeatedly generating near-rectangular magnetic pulses and enables the generation of configurable and stable magnetic pulses without causing excessive device stresses. The introduced device enables the production of near-rectangular pulse trains for modulated magnetic stimuli. The maximum positive pulse width in the proposed neurostimulator is up to 600 µs, which is adjustable by the operator at the step resolution of 10 µs. The maximum transferred energy to the treatment coil was measured to be 100.4 J. The proposed transcranial magnetic stimulator (TMS) device enables more flexible magnetic stimulus shaping by H-bridge architecture and parallel IGBTs, which can effectively mitigate the current stress on power switches for repetitive treatment protocols.

Investigation of reliability assessement in power electronics circuits using machine learning

<p>Recent advances in power electronics (PE) and machine learning (ML) have prompted the technologists to adapt these new technologies to improve the reliability of PE systems. During the process, a lot of investigations on the performance and reliability of PE systems is carried out. The intention of this paper is to present a comprehensive study of advances in the field of reliability of PE systems using machine learning. Recent publications in this regard are analysed and findings are tabulated. In addition to this, literatures published in the prediction of remaining useful life (RUL) of power electronic components is discussed with emphasis on its limitations.</p>

Harmonics elimination for DC/DC power supply based on piezoelectric filters

This research presents a study, modelling and simulation of the piezoelectric material work as filters (piezoelectric filter) used to eliminate the harmonics in power electronic circuits, high order harmonics are generating due to the high switching frequencies and circuit equipment, detailed simulation is achieved for the piezoelectric filter tested in full-bridge DC/DC converter circuit with resistive load works as dc power supply (12 to 48 volt). As a result, the uses of piezoelectric filters have a great impact on harmonics elimination, which leads to reduce the overall total harmonic distortion leads to increase the efficiency, as well as the output voltage from the dc power supply remain constant by varying the load resistance over a wide range. The dc power supply circuit including the piezoelectric filter has been simulated using PSIM (V9.1) power electronic circuit simulation software.

Effect of Connected Non-Linear Household Appliances on the Disturbance at Frequency Range of 9-150 kHz in the On- Grid Photovoltaic System

Nowadays, the usage of power electronic circuit which is called inverter is increasing especially in household appliances. This inverter technology is the technology that can convert alternating current (AC) to direct current (DC), and this technology may produce disturbance at frequency range 9-150 kHz. In the residential area, a house can be built one of on-grid photovoltaic (PV) system, and the usage of household appliances inside the house system can be connected together at same time and operated simultaneously. This research is focused on investigating the effect of connected household appliances, such as induction cooker. The result shows that the connected two types of induction cooker in same system may either increase or decrease the disturbance value in the system. The connected appliances affect the disturbance through by the power consumption.

GaN HEMT on Si substrate with diamond heat spreader for high power applications

Currently, the GaN-on-silicon high electron mobility transistor (HEMT) is a promising candidate to replace the Si Metal Oxide Semiconductor Field Effect Transistor (MOSFET) for high power electronics circuits. However, self-heating is still a challenging issue to be addressed, especially for high-current applications. In this paper, a GaN-on-Si HEMT with a diamond (Dia) heat spreader is proposed to suppress the self-heating effect. The performance of the proposed device is analyzed and compared with conventional GaN-on-Si and also GaN-on-SiC devices. The analysis was carried-out using technology computer aided design. The GaN-on-Si with diamond heat spreader suppresses the self-heating in the device and achieves higher saturation drain current than conventional GaN-on-Si. In addition, GaN-on-Si with Diamond heat spreader yields a higher transconductance and cut-off frequency than GaN-on-Si. This improved structure will provide a low cost device with enhanced thermal characteristics for higher power applications.

Incorporating the Dynamic Threshold Voltage Into the SPICE Model of Schottky-Type p-GaN Gate Power HEMTs

The threshold voltage (VTH) of an enhancement-mode Schottky-type p-GaN gate high-electron-mobility transistor (HEMT) is found to have a special dependence on the drain bias. The device commonly requires higher gate voltage to switch on the transistor from a high-drain-voltage off-state than what is expected from the static device characteristics. The reason behind the dynamic VTH has been proved to be the floating p-GaN layer, where charges could be stored and further influence VTH under different drain bias. In this article, a SPICE-compatible equivalent circuit model is presented according to the structure of Schottky-type p-GaN gate HEMTs. It features a floating node to imitate the charge storage process within the gate stack. Compared to conventional models, the proposed model could accurately predict the dynamic VTH characteristics and switching behaviors of power electronics circuits, where Schottky-type p-GaN gate HEMTs are deployed as power transistors. The phenomena related to the dynamic VTH, including the disappearance of Miller plateau, the overestimated false-turn-on problem, and the higher reverse conduction loss are evaluated with a half-bridge circuit and the merits of the proposed model are verified.

A Real-Time Real-Power Emulator for a Medium-Voltage High-Speed Electrical Drive: Discussion on Mechanical Vibrations

This article, based on modeling and scaling as well as simulation and experiment, provides a comprehensive discussion on a real-time real-power emulator for a medium-voltage, high-power, high-speed motor drive. A three-phase modular multilevel double-star chopper-cell (DSCC) inverter under test is connected in front-to-front (FTF) with the emulator. The DSCC inverter is the same in circuit configuration as the DSCC rectifier. This emulator is characterized by integrating mechanical dynamics of both motor and load into it. The power-electronic circuit of the emulator consists of a three-phase DSCC rectifier, three ac inductors, and a single two-winding common-mode inductor at the dc side. This article starts with modeling and scaling of a three-phase 6.6-kV 10.9-MW four-pole 9000-r/min induction motor drive. Then, the authors design, build, and test a three-phase 200-V 10-kW downscaled test bench. Experimental waveforms from the 10-kW test bench, as well as simulated waveforms from the 10.9-MW full-scale and 10-kW downscaled systems, lead to the following conclusion: The emulator can reproduce both electrical and mechanical dynamics of the three-phase 200-V, 10-kW, four-pole, 9000-r/min induction motor coupled with a centrifugal compressor.

Motor-Oriented Discrete State Event-Driven Method for Multitime-Scale Simulation of Power Traction Systems

With the development of electric vehicles and high-speed train, the demand for power traction system (PTS) is on the rise. Its stability greatly relies on the performance of power traction converters, whose faults are mainly due to the microsecond- or nanosecond-level switching transient process. To avoid overheat or overvoltage failures, researchers should consider this ultrafast dynamics in power switches during the design phase, preanalyzing transient features such as voltage peak and power loss. Nevertheless, the simultaneous simulation of system dynamics and switching transient, namely multitime-scale simulation, is not easily achievable with current software because of their low efficiency and convergence issue. While the discrete state event-driven (DSED) approach can realize efficient multitime-scale simulation for converters, it is incapable of solving circuits connected with nonlinear elements, e.g., motors. This article demonstrates a motor-oriented interfacing derivative (MID) method for connecting motors with power electronic circuits based on DSED. With this method, a multitime-scale platform capable of simulating large-scale PTSs while providing detailed information such as switching transients is built, which is potentially an accurate and efficient tool for system design. Using this platform, the simulation of modular multilevel converter traction system could be finished 200 times faster than the existing commercial multitime-scale simulation software while being capable of capturing switching transient. The proposed MID method enables an efficient multitime-scale numerical platform for PTSs, which facilitates the overall and iterative design for traction systems, especially those of large scale.

Analysis of a GaN based PWM AC-AC converter with an improved switch loss model

AC-AC converters have a wide range of use in industrial applications mostly with installed silicon switches. In last decade, GaN’s are served to market with their high efficiency and fast on-off times, hence implementation of GaN’s to any conventional power electronic circuit is a focus of interest. In this paper, effects of both GaN and MOS switches on efficiency of an AC-AC converter were analysed both numerically and practically. A new extended mathematical loss model proposed by the authors was used to calculate the switching-conduction losses. Laboratory tests were performed with same physical circuit for both switches having the same package. Calculated and measured efficiencies and loss results which are in great harmony proved that the proposed mathematical loss model is extraordinarily realistic. All-in-all, it was observed that GaN and MOSFET switches have both high efficiencies (greater than 96.5%) at low switching frequencies, even though they operate at low power levels. With increasing switching frequency, GaN’s efficiency is slightly reduced (less than 0.5%) while that of MOSFET decreased dramatically almost by 3%. Besides, it was seen that at low frequencies, reverse diode has a significant effect on efficiency of a fast switch, although switching-conduction losses are extremely low.

Modeling Power GaN-HEMTs Using Standard MOSFET Equations and Parameters in SPICE

The device library in the standard circuit simulator (SPICE) lacks a gallium nitride based high-electron-mobility-transistor (GaN-HEMT) model, required for the design and verification of power-electronic circuits. This paper shows that GaN-HEMTs can be modeled by selected equations from the standard MOSFET LEVEL 3 model in SPICE. A method is proposed for the extraction of SPICE parameters in these equations. The selected equations and the proposed parameter-extraction method are verified with measured static and dynamic characteristics of commercial GaN-HEMTs. Furthermore, a double pulse test is performed in LTSpice and compared to its manufacturer model to demonstrate the effectiveness of the MOSFET LEVEL 3 model. The advantage of the proposed approach to use the MOSFET LEVEL 3 model, in comparison to the alternative behavioral-based model provided by some manufacturers, is that users can apply the proposed method to adjust the parameters of the MOSFET LEVEL 3 model for the case of manufacturers who do not provide SPICE models for their HEMTs.

Electrothermal Modeling of the Insulated Gate Bipolar Transistor (IGBT) Using PSpice: Application to DC–DC Converter

In this paper, an improved electrothermal model of power IGBT was developed. The main local physical effects were taken into consideration. The suggested model is able to address the electrical and thermal effects. The model was confirmed through a comparison with other models having close characteristics for different circuits (DC–DC converter, turn-on and turn-off) and different temperatures. The IGBT model was implemented in the PSpice circuit simulation platform using PSpice standard components and analog behavior modeling (ABM) blocks. The IGBT switching performance was investigated under influence of different circuit elements (such as stray inductance, gate resistance and temperature) in order to study and estimate the on-state and switching losses pre-requisite for the design of various converter and inverter topologies. The comparison shows that these models are simple, tunable with the electric circuit software simulator. They are more capable of predicting the main circuit parameters needed for power electronic design. The transient thermal responses were demonstrated for the single pulse and repeat modes. The achieved results show that our model is suitable for full electrothermal simulations of power electronic circuits.

A simple multi‐frequency multiload independent power control using pulse density modulation scheme for cooking applications

Induction heating applications aided by power electronic control have become very attractive in the recent past. For cooking applications, power electronics circuits need to feed power to multi loads with a suitable control technique. The induction heating system requires a superlative converter topology and independent control to deliver power to multi loads. The main idea of this research work is to develop a dual-frequency half-bridge series resonant high-frequency inverter feeding power for multi loads independently. A pulse density modulation (PDM) control technique is used to control the output power independently. The inverter simultaneously powers both loads with constant switching frequency. The proposed system is simulated in MATLAB/Simulink and thermal analysis is carried out in COMSOL multi-physics software. A 1 kW prototype experimental set up is developed to feed power to dual load with the switching frequencies of 20 and 80 kHz for load 1 and load 2, respectively. The experimental results are provided to validate the system performance for various duty cycles of the PDM signal. The simulation and experimental results are in good agreement. The efficient power control is accomplished by varying the density of the switching pulses.

Improving Numerical Accuracy in Time-Domain Simulation for Power Electronics Circuits

In time-domain simulations of power system transients, trapezoidal integration with fixed step-size is the most common method due to its accuracy and ease of implementation. Discontinuities occurring within fixed time-step when simulating power electronics circuits, may cause numerical oscillations and errors. Several methods are available in the literature for interpolation and handling of discontinuities. This paper intends to analyze how accuracy is affected by existing techniques for handling discontinuities in time-domain simulations based on the trapezoidal integration method. New algorithms are proposed to improve accuracy.

Design a Half Bridge Inverter and a Full Bridge Inverter with Overload Protection Circuit Using IC555

Inverter is a power electronic circuit that converts the direct voltage (DC) to an alternating voltage (AC). Inverters are used in a range of applications from consumer electronics and industrial to renewable energy. The flexible capability to create an AC signal from a DC voltage, frequency and speed control are all accomplished from the use of Inverter. Inverter takes the voltage and passes it through switching elements which turn the DC signal into an AC square wave signal. This wave is then passes through filter which turns it into a sine wave signal of the required voltage. This paper presents design an inverter with overcurrent protection circuit without microcontroller, where the MOSFET gate driver is controlled by pulses generated from 555 timer, and with using a low pass filter and setup transformer, a low cost sine wave inverter has been obtained. The heart of the design is 555 timer. The design is achieved in Proteus 8. Simulation results demonstrated that a single phase sine wave (50 Hz) has been generated by a half bridge inverter and a full bridge inverter and protection circuit from current higher than 4.5A has been built. The reliability and accuracy of the system are verified through an experiment.

News From Japan

Power electronics have been playing a big role in many fields of our daily lives. However, as has been well known, at least among high voltage electrical insulation engineers for these two decades, this situation brings about a drastic increase in the risk of partial discharges (PDs). That is, compared with ac voltages with sinusoidal wave shapes at frequencies of 50 or 60 Hz, voltages fed from or induced by power electronic circuits or devices such as converters and inverters contain much shorter fronts and tails in their waveforms. In addition, such devices generate surge voltages with higher amplitudes. Therefore, as power electronic devices are used more and more widely, PDs could be induced much more frequently. This, in turn, increases the importance of monitoring the occurrence of PDs in electric power apparatus such as transformers and rotating machines like motors and generators. However, it is in general difficult for conventional PD testers to monitor PDs generated by such converter-fed voltages. With this background, ECG Kokusai Co., Ltd., Tokyo, has developed a variety of PD testers. In this short article, two of them are briefly introduced.

EMC improvement for high voltage pulse transformers by pareto-optimal design of geometry structure based on parasitic analysis and EMI propagation

High voltage pulse transformers have an essential role in pulsed power systems and power conversion applications. Improving the electromagnetic behavior of such devices leads to better efficiency and low-level electromagnetic interference (EMI) noise propagation in systems. In this paper, a high voltage pulsed power system is considered and analyzed to improve the electromagnetic compatibility (EMC). The new generation of pulsed power systems that use SiC and GaN fast switches in capacitor charger power electronic circuit, face far more EMI challenges. Moreover, in this paper, the EMI propagation paths in the pulsed power system are realized and analyzed. The EMI noise level of the system is obtained and compared to the IEC61800-3 standard. To improve the EMC, the parasitic parameters of the transformer, as the main path of EMI circulation, are optimized to block the EMI propagation in the pulsed power system. For this aim, the parasitics are modeled and calculated with a novel and accurate energy distribution model. Then, by defining a cost function the geometry structure of the transformer is optimized to lower the parasitics in the system. Three pareto-optimal techniques are investigated for the cost function optimization. The models and results are verified by 3D-finite element method (FEM) and experimental results for several given scenarios. FEM and experimental verifications of this model, make the model suitable for any desirable design in any pulsed power systems. Finally, the EMI noise level of the system after optimization is shown and compared to the IEC61800-3 standard.

The Method of the SiC MOSFET Replacing the Si IGBT in the Traditional Power Electronics Converter without Redesigning the Main Circuit and the Driver Circuit

As a wide bandgap power electronics device, the SiC MOSFET has a lot of advantages over the traditional Si IGBT. Replacing the Si IGBT with the SiC MOSFET in the existing power electronics converter is an effective means to improve the performance and promote the upgrading of the traditional converter. Generally, in order to make full use of its advantages of the SiC MOSFET, the Si IGBT in the traditional power electronics circuit cannot be simply replaced by the SiC MOSFET, but the main circuit and the driver circuit need to be redesigned because the oscillation problem and the cross-talk problem caused by the parasitic parameter are very serious when the SiC MOSFET switches. However, considering the low cost and the short cycle requirement of the equipment development, it is often difficult to redesign the circuit hardware structure of all converters. In order to resolve this contradiction, a ferrite bead based method is proposed in this paper. Through this method, without redesigning the hardware structure of the main circuit and the driver circuit, the SiC MOSFET can be used to replace the Si-based power electronics device directly, and the loss of the converter can be reduced with small oscillation. Finally, the effectiveness of the proposed method is proved by experiments.