Load Independent Operation Research Articles

Double Coupling In-Wheel IPT System for Electric Vehicles

The electric automotive industry revolutionizes the transportation sector with new disruptive technologies like wireless charging systems and the tire industry is no exception. New airless and sustainable tire designs offer new possibilities to embody wireless charging technologies. This paper presents a novel in-Wheel Inductive Power Transfer (inWIPT) batteries charger design for electric vehicles (EV). The proposed system uses two magnetic couplers (MC) to transfer the energy: one from the off-board side to the wheel and another from the wheel to the on-board side. The proposed configuration keeps the air gap between the off-board transmitter pad and the wheel receiver to a minimum and almost independent of the vehicle type (Sedan, Suv, Truck). The two MCs are connected by a new resonant tank which modifies the voltage transfer characteristics. A step by step methodology that identifies the operational range of the mutual inductances, based on certain design specifications and constraints, is also presented. Experimental results validate the proposed inWIPT in a quasi load independent voltage operation in different coupling charging scenarios and a maximum output power of 2.6 kW with an efficiency of 89.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> .

Feasibility Analysis of a Reduced Capacitive Wireless Power Transfer System Model for Transportation Electrification Applications

A practical approach in modeling a capacitive wireless power transfer (CPT) system that utilizes an electrostatic field for the power transfer is presented in this article. The reduced capacitance model (RCM) is derived from the conventional six capacitance model (SCM) for the CPT system in view of the large charging area applications, such as electric vehicle charging. The effect of the same side and cross-coupling capacitances diminishes when the separation distance between the same side plate pair is large enough, and the reduced capacitance model (RCM) is obtained. A bipolar capacitive-link dispersion distance proposed in this article acts as an indicator to decide the use of RCM or SCM depending on the application. Furthermore, RCM attains unity voltage gain and load-independent operation at the designed single resonant frequency, unlike the SCM, where the influence of multiple resonant frequencies is predominant. An experimental validation is performed to determine the effectiveness of the RCM.

Load-Independent Push–Pull Class E$ ^2$ Topology With Coupled Inductors for MHz-WPT Applications

This article investigates the modeling and implementation of the load-independent operation for the push–pull Class E topology with coupled inductors. The analytical modeling is first presented and provides a new design methodology, which distantly improves the soft-switching performance, load regulation, and efficiency compared with the conventional inductor-coupled Class E topology. An <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC-S</i> resonant Class E <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ ^2$</tex-math></inline-formula> converter, which combines the load-independent inductor-coupled inverter and active rectifier, is proposed for MHz-wireless power transfer (MHz-WPT) applications. The active inductor-coupled Class E rectifier maintains soft switching, constant voltage gain, and zero-phase-angle input at various loads. A three-winding magnetic structure is also proposed to improve the coupled inductors by enhanced self-inductance, which features more effective harmonic suppression with lower magnetic losses and volumes. By the proposed methodology and the improved magnetic structure, the converter features negligible harmonic contents and maintains soft switching with a constant voltage conversion ratio over the entire load range. A 6.78-MHz WPT prototype was built to verify the proposed methodology with detailed parameter design and hardware implementation. The prototype realizes load-independent zero-voltage switching and maintains an approximately constant voltage gain with +5/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 4% variance from no-load to 320-W output power. The measured dc–dc efficiency reaches 89.3% at 210 W.

Generalized Analysis of Load-Independent ZCS Parallel-Resonant Inverter

This article proposes a load-independent zero-current switching (ZCS) parallel-resonant inverter along with its analytical expressions and a design method. The proposed inverter achieves constant output voltage amplitude and ZCS against load variations, which are called the load-independent operation in this article. The analytical expressions provide design equations for achieving the load-independent operation. The analytical expressions and the design equations were verified from the quantitative agreements between the experimental measurements and analytical predictions.

Synchronous Push–Pull Class E Rectifiers With Load-Independent Operation for Megahertz Wireless Power Transfer

This article presents the analytical modeling of synchronous class E rectifiers with the load-independent operation, which achieves zero-phase-angle input impedance, soft-switching over the entire load range with a constant voltage gain. The optimal design of the synchronous class E rectifier is proposed to realize both zero-voltage-switching turn-ON and zero-current-switching turn-OFF at the expected output power. An LCC-S compensated MHz-WPT topology, which comprises the push-pull class E inverter and rectifier with the load-independent operation, is proposed to achieve the fully soft-switching and a nearly constant voltage gain over the entire load range. The efficiency improvement of the compensation network is also investigated to provide a design methodology for the proposed topology. A 6.78-MHz WPT prototype, along with an alternative phase detector using an auxiliary coil to realize phase detection, is built to validate the analytical model and the proposed methodology. The system efficiency reaches 86.7% at 214-W output. The synchronous push-pull class E rectifier maintains soft-switching over the load range, and the rectification efficiency reaches 94.6%.

Output Voltage Range of a Power-Loaded Series–Series Compensated Inductive Wireless Power Transfer Link Operating in Load-Independent Regime

The article proposes an in-depth analysis of a series-series compensated resonant inductive wireless power transfer (WPT) link, operating at load-independent frequency while feeding a power load. It is shown that due to the presence of equivalent series resistances in practical systems, a load-independent operation point is only an approximation. The output voltage is still affected by the load, obtaining minimum and maximum values under rated load and no-load operation, respectively. While the output voltage value under rated load is typically well predicted by the commonly used first-harmonic-approximation-based equivalent circuit, the latter is unsuitable for obtaining the output voltage value under light loading due to nonlinearity caused by the discontinuous conduction mode of the secondary. Time-domain analysis is, therefore, used to accurately predict the WPT output voltage value under zero-load operation and accurately derive the expected WPT output voltage range in the load-independent regime. Simulations and experiments based on a 400-V 1-kW WPT link demonstrate excellent matching, validating the proposed analysis.

Load-Independent Class E/EF Inverters and Rectifiers for MHz-Switching Applications

This paper presents a unified framework for the modeling, analysis, and design of load-independent Class E and Class EF inverters and rectifiers. These circuits are able to maintain zero-voltage switching and, hence, high efficiency for a wide load range without requiring tuning or use of a feedback loop, and to simultaneously achieve a constant amplitude ac voltage or current in inversion and a constant dc output voltage or current in rectification. As switching frequencies are gradually stepping into the megahertz (MHz) region with the use of wide-bandgap (WBG) devices such as GaN and SiC, switching loss, implementing fast control loops, and current sensing become a challenge, which load-independent operation is able to address, thus allowing exploitation of the high-frequency capability of WBG devices. The traditional Class E and EF topologies are first presented, and the conditions for load-independent operation are derived mathematically; then, a thorough analytical characterization of the circuit performance is carried out in terms of voltage and current stresses and the power-output capability. From this, design contours and tables are presented to enable the rapid implementation of these converters given particular power and load requirements. Three different design examples are used to showcase the capability of these converters in typical MHz power conversion applications using the design equations and methods presented in this paper. The design examples are chosen toward enabling efficient and high-power-density MHz converters for wireless power transfer (WPT) applications and dc/dc conversion. Specifically, a 150-W 13.56-MHz Class EF inverter for WPT, a 150-W 10-MHz miniature Class E boost converter, and a lightweight wirelessly powered drone using a 20-W 13.56-MHz Class E synchronous rectifier have been designed and are presented here.

Investigation of fuzzy control based LCL resonant converter in RTOS environment

This paper presents a comparative evaluation of Fuzzy Logic FLC Controller and Open loop Controller for a modified LCL Resonant Converter has been simulated and the performance is analyzed. A three element LCL Resonant converter working under load independent operation is presented in this paper. In this work, the applicability of the ARM Advanced RISC Machine processor LPC 2148 is to be investigated as the controller for resonant converter. The simulation study indicates the superiority of Fuzzy Logic control over the conventional control method. The evaluation version of MATLAB was used to model the LCL topology for varied loads and LCL configurations. A LCL Resonant Inverter is proposed for applications in high frequency distributed AC power systems and Resonant Converter is proposed for applications in many space and radar power supplies. The advantages of the LCL topology are low total harmonic distortion THD high efficiency and the ability to handle varying loads.

Experimental verification and stability state space analysis of CLL–T series parallel resonant converter with fuzzy controller

This paper presents a closed loop CLL-T (capacitor inductor inductor) series parallel resonant converter (SPRC) has been simulated and the performance is analyzed. A three element CLL-T SPRC working under load independent operation (voltage type and current type load) is presented in this paper. The stability and AC analysis of CLL-T SPRC has been developed using state space technique and the regulation of output voltage is done by using Fuzzy controller. The simulation study indicates the superiority of fuzzy control over the conventional control methods. The proposed approach is expected to provide better voltage regulation for dynamic load conditions. A prototype 300 W, 100 kHz converter is designed and built to experimentally demonstrate, dynamic and steady state performance for the CLL-T SPRC are compared from the simulation studies.

DSP based fuzzy controller for series parallel resonant converter

In this paper, digital signal processor (DSP) based fuzzy controller for series parallel resonant converter (SPRC) has been estimated, and the performance of the converter is analyzed by using state space model. The method to predict the steady-state and dynamic performance of the converter with load independent operation has been presented. The proposed converter has been analyzed with the closed-loop and open-loop conditions. The simple form of transfer function for SPRC is developed, and it is used to analyze the stability of the converter with closed-loop operation. The stability analysis of the converter is carried out by using frequency response plan. The fuzzy controller regulates the output voltage with change supply voltage and load disturbance. The controller performance of inductance capacitance inductance — T network (LCL-T) SPRC is compared with inductance inductance capacitance — T network (LLC-T) SPRC through simulation and experimental studies using TMS320F2407 processor.

Investigation of closed-loop performance for an LCL resonant converter in a real-time operating system environment

This study presents a comparative evaluation of proportional integral (PI) controller and fuzzy logic controller (FLC) for a modified Inductance-Capacitance-Inductance resonant converter. It has been simulated and the performance is analysed. A three-element LCL resonant converter working under load-independent operation is presented in this study. In this study, the applicability of the Philips Advanced RISC Machine (ARM) processor LPC 2148 is also investigated as the controller for resonant converter. The comparison study indicates the superiority of fuzzy control over the conventional control methods and these results are presented. MATLAB was used to model the LCL topology for varied loads and LCL configurations. The LCL resonant inverter is proposed for applications in high-frequency distributed AC power systems and resonant converter is proposed for applications in many space and radar power supplies. This study presents the design, simulation and experimental results for a 133-W, 50-KHz LCL resonant converter having efficiencies &gt;89% down to resistive loads of 50%. Efficiencies &gt;80% were obtained at significantly reduced loads (11%).

Embedded Control of LCL Resonant Converter Analysis, Design, Simulation and Experimental Results

The Objective of this paper is to give more insight into CCM Operation of the LCL Converter to obtain op-timum design using state-space analysis and to verify the results using PSPICE Simulation for wide variation in loading conditions. LCL Resonant Full Bridge Converter (RFB) is a new, high performance DC-DC con-verter. High frequency dc-dc resonant converters are widely used in many space and radar power supplies owing to their small size and lightweight. The limitations of two element resonant topologies can be over-come by adding a third reactive element termed as modified series resonant converter (SRC). A three ele-ment resonant converter capable of driving voltage type load with load independent operation is presented. We have used embedded based triggering circuit and the embedded ‘C’ Program is checked in Keil Software and also triggering circuit is simulated in PSPICE Software. To compare the simulated results with hardware results and designed resonant converter is 200W and the switching frequency is 50 KHz.

An LCL resonant converter with PWM control-analysis, simulation, and implementation

A three element resonant converter capable of driving a voltage type load with load independent operation is analyzed using a state-space approach. Pulse width modulation is employed to control and regulate the output voltage. Closed-form solutions are obtained under steady state conditions. The experimental study of a prototype converter reveals complete agreement with the analytical and SPICE simulation results. Typical experimental oscillograms are given to verify the basic principles.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The infeasibility of self-regulating constant-current-fed class E power inverters

Because of their high operating efficiency, class E circuits have been shown to be useful in high-frequency power inverters and converters. Typical circuits are constant-fed, i.e. they require an RF choke in the DC-feed line, and must obtain load regulation by means of appropriate feedback control. A class E inverter with finite DC-feed inductance that provides perfect load regulation without feedback control has been suggested. However, such class E circuits generally have higher sensitivities to component variations (except load resistance) than do their constant-current-fed counterparts. Thus, the possibility of load-independent operation of constant-current-fed class E inverters is of interest. The authors show that there is no way to configure constant-current-fed E inverter so that it will exhibit load-independent properties except for a trivial circuit with zero output voltage.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>