Switched-mode Power Converters Research Articles

Design and Implementation of Closed Loop SEPIC Converter for PV System Based Smart Home Application

The design, simulation, and analysis of the Single- ended primary-inductor converter (SEPIC), one of the least known Switch mode power converters, are presented in this study. By adjusting the switching element's duty cycle, this dc-dc converter may be utilized as a buck-boost converter. With minimal strain on components, SEPIC offers the specific benefit of offering positive polarity output voltage and ripple-free input and output current. This contrasts with conventional buck-boost converters, which have negative polarity output voltage along with extremely irregular currents and increased component stress. This makes it perfect for both commercial and personal uses, such as smart home gadgets that use PV energy. Under various input circumstances, extensive simulation has been performed in continuous conduction mode (CCM) utilizing SIMULINK-MATLAB. A PI controller has been added to optimize the responsiveness, reduce steady state error, and keep the output voltage constant. The SEPIC converter's hardware implementation verifies the simulation's findings.

Nonlinear Quadratic Regulator Design With a Hybrid Switching Scheme for Wind Turbine Generators

This article proposes a new control scheme with a nonlinear quadratic regulator (NQR) associated with a hybrid switching stage for permanent magnet synchronous generator-based wind turbines (WTs). The proposed method shows a new approach combining a nonlinear optimal control method with a hybrid switching stage for WT generations (WTGs). As the WTG is a nonlinear system, NQR control design is directly employed to deal with the nonlinearity while a hybrid switching scheme can deal with constrained control inputs as discrete nonlinear characteristics of switch-mode power converters. A polynomial-based dynamic model is derived for the new NQR design. Unlike the previous state-dependent Riccatti equation (SDRE) technique where the solution of the nonlinear optimal controller is approximated, this technique finds the exact online solution of SDRE with nonlinear feedback gains flexibly depending on the tracking error. Then, the optimal control laws are implemented via a hybrid switching stage ensuring a smooth current regulation under a reduced switching frequency while avoiding any complicated modulator or finite state search. The proposed control design is investigated via comparative studies with linear quadratic regulator (LQR), direct switching, and space-vector pulse-width-modulation stages (SV-PWMs) implemented in both platforms of MATLAB/Simulink and real-time OPAL-RT. Comparative results exhibit flexible optimal performances via online hyper-parameter tuning to reduce the speed tracking error and low current ripples under a reduced switching frequency.

Accurate Modeling of CCS Combo Type 1 Cable and Its Communication Performance Analysis for High-Speed EV-EVSE Charging System

This paper addresses the issue of electromagnetic interference (EMI) in electric vehicle supply equipment (EVSE) charging cables, which can disrupt the communication signal for the real-time monitoring of the charging status, leading to the termination of charging. We propose a dedicated measurement jig for the Combined Charging System Combo Type 1 (CCS-CT1) cable structure and models its electrical characteristics of the jig using the impedance peeling technique for de-embedding. The obtained pure S-parameters of CCS-CT1 are then used to conduct a simulation of the signal integrity problem caused by Gaussian noise, which is the worst-case scenario that can occur in a typical charging system. This paper suggests that the root cause of this problem may be related to the high-power AC/DC conversion device included in the EVSE, which uses a switch-mode power conversion (SMPC) method that involves nonlinear operation and can result in increased harmonic noise and a more complex signal protocol for precise control. Finally, this study provides insights into the challenges of implementing high-speed charging systems and offers a solution for obtaining the accurate electromagnetic characteristics of charging cables.

Design and Optimization of an Integrated Resonant Inductor With High-Frequency Transformer for Wide Gain Range DC–DC Resonant Converters in Electric Vehicle Charging Applications

Large-scale adoption of wide band gap semiconductors in switched mode power converters enables miniaturization of power electronic systems. With switching frequencies approaching a few hundred kilohertz - megahertz range, efficient and compact design of magnetic components are crucial for future generation power supplies in data centers or electric vehicle (EV) applications. In a typical two-stage AC-DC power supply, the DC-DC stage is often constructed using a resonant converter with galvanic isolation provided by a high-frequency transformer. In such systems, the integration of an inductor in the resonant network with the transformer helps improve power density and reduces component count and cost. However, the integration of magnetic components can result in increased losses, deteriorating the performance of the power conversion system. In this paper, a magnetic structure along with an optimization methodology is presented to integrate a predefined resonant inductor as leakage inductance of the high-frequency transformer achieving minimum penalty on converter efficiency using planar core geometry and printed circuit board (PCB) based windings. The proposed methodology is applied to integrate a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$7.8 \mu \rm{H}$</tex-math></inline-formula> inductor with a 2:1 transformer for a 6.6 kW, 500 kHz LCL-T resonant DC-DC stage utilizing GaN transistors in an onboard battery charging converter. On the prototype converter using the optimized integrated magnetic component, a peak efficiency of 98.4% was obtained using PCB windings. Furthermore, the integrated magnetic component achieved 64 kW/L power density in the demonstrator prototype.

A Novel Version of the Ripple-Modulation Technique for Enabling the Use of Single-Phase Buck Converters in VLC Applications

Visible light communication (VLC) has recently emerged as a promising technology for alleviating the saturation of the radio frequency (RF) spectrum. VLC uses high-brightness light-emitting diodes (HB-LEDs) both for lighting and communication. In particular, the information transmission is carried out by performing fast changes of the light intensity emitted by the HB-LEDs. The conventional VLC driver includes a linear power amplifier (LPA) for reproducing the communication signal. Unfortunately, this approach penalizes the efficiency. During the last years, a wide variety of VLC drivers fully based on the use of switching-mode power converters (SMPCs) have been proposed to overcome the efficiency limitation. One of the most promising approaches is the ripple-modulation (RM) technique, which consists in using the output voltage ripple of an SMPC to reproduce the communication signal. However, the conventional RM technique has a major drawback: it can only be applied to multiphase buck converters. This work is focused on overcoming that limitation by introducing a novel version of the RM technique that enables the use of a single-phase buck converter. In this way, the work aims to reduce the required power-stage complexity, which is a critical parameter of HB-LED bulbs. Moreover, a novel output filter structure is proposed to reduce the total harmonic distortion of the reproduced signal. A ripple-modulated buck converter prototype was built with an output power and a switching frequency of 8 W and 2 MHz, respectively. Moreover, the reproduced passband modulation scheme provides a bit rate of up to 1.25 Mb/s with a communication range of 100 cm and a peak efficiency of 94%.

Closed-Form Implicit Models for Efficient Simulation of Power Electronics

This document describes novel closed-form implicit (CF-implicit) models of switched-mode power converters, which feature implicit integration but require no iterative numerical solving algorithm for evaluation because they are explicitly solved in CF prior to model execution. The derived models capture the large-signal dynamic behavior of the power converters, so their use and accuracy are not limited to any one set of operating conditions. These models can be directly implemented in any computational environment, including directly on an existing embedded controller. Since no iterative solver is required, the models are highly computationally efficient and have a very predictable worst case execution time (WCET), which makes them especially suitable for real-time (RT) modeling applications, such as hardware-in-the-loop (HIL) simulation or digital twins (DTs). The model derivation process is demonstrated by example on a two-stage power converter, and computational expense is analyzed. A discussion of model error is also included.

Steady-State Indeterminacy in Lossless Switched-Mode Power Converters

In this article, it is shown for the first time that lossless switched-mode power converters may not possess a unique steady-state solution. Rather, they can exhibit an inherent <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">indeterminacy</i> in their steady-state behavior, and a unique solution is only found when losses are included in the analysis. Even more interestingly, it is shown that lossless converters of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">odd order</i> never possess a unique steady-state solution. Indeterminate converters can be intrinsically sensitive to parasitic resistances and other nonideal effects, a phenomenon that practically manifests itself in the form of undesirable voltages or circulating currents possessing, in general, both dc and ac components. This article first sets a general mathematical framework for a systematic assessment of steady-state indeterminacy. This is subsequently linked to the geometry of the state vector periodic motion in the converter's <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -dimensional state space. On the basis of the developed theory, odd-order converters are shown to always be affected by the indeterminacy issue. Besides inherent theoretical importance in the power electronics field, the results of this article provide a deeper justification for the observed behavior of several converter topologies of significant practical relevance, the most notable being multiphase and multilevel dc–dc converters, examples of which are discussed as case studies.

A Reconfigurable Setup for the On-Wafer Characterization of the Dynamic RON of 600 V GaN Switches at Variable Operating Regimes

Charge-trapping mechanisms observed in high-voltage GaN switches are responsible for the degradation of power converter efficiency due to modulation of the effective dynamic ON-resistance (RON) with respect to its static value. Dynamic RON degradation is typically dependent on the blocking voltage and the commutation frequency and is particularly significant in new technologies under development. The possibility to characterize this phenomenon on GaN switch samples directly on-wafer, under controlled operating conditions that resemble real operations of the DUT in a switching mode power converter is extremely valuable in the development phase of new technologies or for quality verification of production wafers. In this paper, we describe a setup that allows this characterization: dynamic RON degradation of on-wafer 600 V GaN switches is characterized as a function of the VDS blocking voltage, the VGS driving voltage, and at different temperatures. The dependency on the switching frequency is identified by measuring the current recovery of the switch after the application of blocking voltages of different durations.

Characterization of the Dynamic RON of 600 V GaN Switches under Operating Conditions

High-voltage GaN switches can offer tremendous advantages over silicon counterparts for the development of high-efficiency switching-mode power converters at high commutation frequency. Nonetheless, GaN devices are prone to charge-trapping effects that can be particularly relevant in the early-stage development of new technologies. Charge-trapping mechanisms are responsible for the degradation of the dynamic ON-resistance (RON) with respect to its static value: this degradation is typically dependent on the blocking voltage, the commutation frequency and temperature, and is responsible for the reduction of power converter efficiency. The characterization of this phenomenon is very valuable for the development of a new process to compare different technological solutions or for the final assessment of performance. This characterization cannot be made with traditional static or small signal measurements since RON degradation is triggered by application-like dynamic device excitations. In this paper, we propose a technique for the characterization of the dynamic RON of high-voltage GaN switches under real operating conditions: this technique is based on the design of a half bridge switching leg in which the DUT is operated under conditions that resemble its operation in a power converter. With this setup, the characterization of a 600 V GaN switch dynamic RON is performed as a function of variable blocking voltages and commutation frequency. Additionally, this technique allows the separation of thermal and trapping effects, enabling the characterization of the dynamic RON at different temperatures.

Overview of Talkative Power Conversion Technologies

Power Line Communication (PLC) and Simultaneous Wireless Information and Power Transfer (SWIPT) are popular examples of applications, where power and information are transmitted simultaneously. In most cases, different devices have been used to generate the power and communication signals independently. Usually, the information is superimposed onto the power signal using an external modulator. Recently, power converters have been used to generate pulses not just for power conversion but also for information transfer simultaneously. This approach represents a fundamental difference because it exploits the signal processing potential of Pulse Width Modulation (PWM), where for power conversion only the average pulse width is used, while the information is represented by the harmonics instead of being filtered out, as typically done in power electronics. The concept of embedding information into the switching ripple generated by a switched-mode power converter has recently been dubbed Talkative Power (TP), in this paper referred as Talkative Power Conversion (TPC). TPC technologies are reviewed in non-isolated and isolated converters in this paper. Potential applications include visible light communications, battery management systems, switching reluctance generators/motors, microgrids, and wireless electric vehicle charging stations. Finally, trending topics are identified.

Which Came First? Part II [White Hot

<fig orientation="portrait" position="float" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <graphic orientation="portrait" position="float" xlink:href="rober-3218356.tif"/> </fig> In my previous column, I started by asking which led the way in the advancement of power electronics technology—devices or topologies? I then reviewed the early history of “switched mode power conversion,” given that converters that used electromechanical switches like vibrators were switched mode power. That column ended with a discussion of the developments in power electronics in the 1960s after the first solid state switches started becoming generally available.

AlScN-Based SAW Magnetic Field Sensor for Isolated Closed-Loop Hysteretic Current Control of Switched-Mode Power Converters

This letter uses a surface acoustic wave magnetic field sensor for measurement and closed-loop current control of the inductor current in a GaN-based dc-dc power converter. The sensor is based on aluminium scandium nitride thin films with relatively high Sc concentration of 32% and fabricated on low-cost 8-in silicon substrate, with a magnetostrictive FeCoSiB film on top of a SAW delay line. The device has dc and bidirectional current measurement capability (derived from the magnetic flux density around a current trace) and is operated electrically isolated above the current trace. With permanent magnets as magnetic bias, the setup has a usable bidirectional current range of ±5 A. A phase detector IC measures the phase shift between the 296 MHz, 19 dBm input, and 35 dB attenuated output signal of the delay line sensor. The active sensor area has a distance of 2.5 mm from the current trace. In a 1.2 mT bias, the sensor is operated with a sensitivity of 18.28°/mT and bipolar current range of up to ±5 A. The sensor signal is enhanced by an analog filter to compensate the over 1 µs delay from the delay line and readout circuit. Finally, the sensor is used as the input of an analog hysteretic current control loop. The closed-loop current control operation is demonstrated using a 48 V GaN-based half-bridge dc-dc converter with 16 kHz triangular inductor current.

Design Optimization of Synchronous Buck Converter (SBC)

Abstract: Nowadays Switched-mode power converters are playing a significant role in the industries by providing higher efficiency for various applications. There are various applications that implement power supply and battery charge circuits for devices like smartphones, TVs, and various electronic devices When it comes to DC-DC Converters the most popular among the industries are buck converters and the efficient version of the buck converter is the Synchronous buck converter. The SBC steps down the voltage from higher to lower levels. Efficiency is a crucial parameter as the industry’s focus is on delivering greater performance devices. The power converter's design must be optimized to maximize performance to achieve customer expectations. As a result, a thorough understanding of the synchronous buck converter and how to properly select the circuit components is critical. The proposed work aims at optimizing the Synchronous Buck Converter components such as Inductors, Capacitors, and Resistors. The idea of this optimization study is to improve the performance of the converter and reduce power losses and cost-cutting. In this paper, the control mode considered is peak current mode control.

Simulation of Switched-Mode Power Conversion Circuits With Extended Impedance Method

Efficient simulation of switched-mode power conversion circuits is necessary for the analysis and optimization of power electronics. This paper introduces the extended impedance method (EIM) to the simulation and analysis of general switched-mode power converter circuits. By using the EIM method, the conventional impedance concept can be extended to involve more linear time-variant (LTV) and nonlinear devices, such as MOSFET switches and diodes, which are commonly used in switched-mode power conversion circuits. EIM models a circuit network from the component level in the frequency domain, rather than from the system-level constitutive differential equation in the time domain. Compared with the conventional averaging method, EIM can reveal more high-frequency features of a switched-mode converter circuit, in particular, those around the switching instants. A buck converter is taken as a representative example to validate the EIM based analysis. Both the simulation and experimental results prove that EIM provides precise numerical results, which match the real waveform, as the commercial simulators, e.g. PSpice and ADS, do. Moreover, it largely reduces the computational complexity towards more efficient and more flexible steady-state analysis of switched-mode power electronics.

Influence of Random Modulated Power Converter on G3 Power Line Communication

Power Line Communication (PLC) technologies are being used in many applications and offer the advantage of utilizing existing power cables for both power and data transmission, thus minimizing cost and complexity. Nevertheless, PLC technology requires further investigation to solve possible co-existence issues. Indeed, recent studies confirmed that alternative modulation schemes such as Random Pulse Width Modulation (RPWM), applied to switching-mode power converters to minimize conducted emissions, detrimentally interfere with the PLC system. This paper presents an experimental test campaign aimed at investigating the effects of RPWM on the G3-PLC system, with the final goal of understanding the conditions under which RPWM schemes can be considered as an effective alternative to conventional Pulse Width Modulation (PWM) in applications involving PLC systems. In details, the effects of different RPWM parameters such as switching frequency, modulation index, and Random Number Update Rate (RNUR) on the G3-PLC is investigated. In addition, different RPWM schemes such as Random Frequency Modulation (RFM) and Random Pulse Position Modulation (RPPM) are compared in terms of performance so as to highlight which RPWM is best suited to assure coexistence with PLC systems. The impact of RPWM on the communication channel is evaluated in terms of Frame Error Rate (FER), Channel Capacity, and Channel Capacity Loss metrics. Experimental results confirmed that randomly modulated converters with switching frequencies near the G3-PLC bandwidth cause more significant disturbance and possible coexistence issues than the switching frequencies out of this range. Results also show that the modulation index and the RNUR of RPWM have a direct effect on the communication channel. Moreover, a trade-off between Electromagnetic Interference (EMI) reduction and coexistence issues is observed: RFM, which is very effective for EMI reduction, is found to be very disruptive for G3-PLC, compared to alternative random modulation techniques such as RPPM.

Pulsewidth Modulated Three-Level Buck Converter Based on Stacking Switch-Cells for High Power Envelope Tracking Applications

Envelope tracking is a well-known RF technique that alleviates the efficiency problem of linear power amplifiers used in wireless communication transmitters. It consists in varying the supply voltage of the amplifier, which is commonly constant, according to the envelope of the communication signal. Therefore, a switching-mode power converter with a bandwidth of several megahertz is required to perform the fast voltage changes needed for tracking the envelope properly. Another important requirement is that the converter needs to be able to achieve high efficiency not only at peak output power, but also at low output power because it operates in that power range most of the time due to the characteristics of modern communication signals. Taking into account these requirements, the design of the converter is very challenging, especially in the case of base stations, where higher power levels are reached by means of higher voltage levels. As a result, transistors with low breakdown voltages (20&#x2013;30 V), which offer the highest speed, cannot be used in the converter. In this article, a novel multilevel converter able to use transistors with low breakdown voltages is proposed to alleviate that problem. Moreover, it shows a better switching behavior than the previously proposed multilevel converters, thus reducing the switching losses and, consequently, increasing the efficiency. In order to experimentally validate the proposed topology, a 73-W prototype with a switching frequency of 8 MHz was built. The efficiency is 94&#x0025; and 81.7&#x0025; at peak output power and at one-tenth of peak output power, respectively.

Equivalent electric circuit model of accurate ion energy control with tailored waveform biasing

For atomic scale plasma processing involving precise, (an)isotropic and selective etching and deposition, it is required to precisely control the energy of the plasma ions. Tailored waveforms have been employed to bias the substrate table to accurately control this ion energy. Recent research has shown that switched-mode power converters can be used to generate this kind of waveform, with the benefit of increased energy efficiency and flexibility compared to the traditionally used linear amplifiers. In this article, an improved equivalent electric circuit model of the plasma reactor is proposed to allow simulation and bias waveform optimization. The equivalent electric circuit is analysed for different process phases, including the charge, discharge, and post-discharge phase. The proposed model is suitable for electric circuit simulation and can be used for predicting the electric waveforms and ion energy distributions. Plasma parameters are required as input for the model, thus an empirical parameter identification method based on the electrical measurements of the bias voltage and output current waveforms is introduced. Since these electrical measurements do not interact with the plasma process, the proposed parameter identification method is nonintrusive. Experiments have been carried out, which demonstrate that the proposed model and parameter identification method provide the expected accuracy.

Interference of Periodic and Spread-Spectrum-Modulated Waveforms with Analog and Digital Communications

In this article, the effectiveness and the limitations of spread-spectrum (SS) modulation techniques employed in switching-mode power converters and in digital systems to mitigate interference with communication equipment are analyzed and discussed under the EMC standard perspective and under an information theoretical perspective, with reference to different real-world scenarios. Substantial difference between potential EMI issues in traditional analog radio/TV broadcasting, digital data lines, and digital links featuring advanced channel coding techniques, e.g. in emerging power line communication (PLC) systems, are highlighted. Practical recommendations on the adoption of SS modulations along with a general reflection on the evolution of EMC requirements are finally given.

Estimation of State Variables in the Ćuk Converter Mathematical Model with Partially Unknown Parameters

In this paper the solution was proposed for the state variables estimation problem in the mathematical model of the DC switch-mode power converter built according to the Ćuk scheme. Pulse converters are one of the main components of most modern electrical devices and the circuit proposed by Slobodan Ćuk in the 70s of the 20th century is still relevant and demanded. Traditionally, PI (proportional-integral) controllers or proportional-integral adaptive control algorithm (PI-PBC), based on passification methods and superior to standard PI controllers in accuracy, are used as the control algorithm for power converters. However, you need to know the entire vector of the state variables of the converter to build a PI-PBC controller, and moreover, all its parameters must be accurately known. Unfortunately, in practice, such assumptions are not fulfilled, since parametric drifting is possible, and measurements of the converter’s state require additional sensors, which in some cases does not justify itself. Thus, there is a need to develop additional observers or estimators that allow obtaining data on all variables of the converter, as well as its parameters. The solution is based on the GPEBO method (generalized parameter estimation-based observers). The problem was solved under assumption that only the output signal (the output voltage of the converter) is measurable and some of the mathematical model parameters are unknown. An important aspect of the observer design is the development of an algorithm for unknown parameters and the state vector of a mathematical model estimation that ensures convergence in a finite time. Finite-time convergence is extremely important when designing observers since transients in pulse converters occur very quickly.

The Effect of EMI Generated from Spread-Spectrum-Modulated SiC-Based Buck Converter on the G3-PLC Channel

Power line communication (PLC) is increasingly emerging as an important communication technology for the smart-grid environment. As PLC systems use the existing infrastructure, they are always exposed to conducted electromagnetic interference (EMI) from switching mode power converters, which need to be tightly controlled to meet EMC regulations and to ensure the proper operation of the PLC system. For this purpose, spread-spectrum modulation (SSM) techniques are widely adopted to decrease the amplitude of the generated EMI from the power converters so as to comply with EMC regulations. In this paper, the influence of a spread-spectrum-modulated SiC-based buck converter on the G3-PLC channel performance is described in terms of channel capacity reduction using the Shannon–Hartley equation. The experimental setup was implemented to emulate a specific coupling path between the power and communication circuits and the channel capacity reduction was evaluated by the Shannon–Hartley equation in several operating scenarios and compared with the measured frame error rate. Based on the obtained results, SSM provides the EMI spectral peak amplitude reduction required to pass the electromagnetic compatibility (EMC) tests, but results in increased EMI-induced channel capacity degradation and increased transmission error rate in PLC systems.