APPLICATION OF BIFURCATION THEORY TO CURRENT MODE CONTROLLED PARALLEL-CONNECTED BOOST DC-DC CONVERTERS

This project is to design a circuit which will guarantee stable operation at switching frequencies, and any quasi-periodic or chaotic operation is regarded as being undesirable and should be avoided. This project focuses in particular on the application of bifurcation theory to parallel-input / parallel-output two-module current-programmed DC-DC converters. Besides, this project describes the operation of Current Mode Controlled Parallel-Connected Boost DC-DC Converters and basically defines chaos, bifurcation and quasi-periodic distortion of the circuit by varying the reference current and comparing it with inductor output current. Within specific ranges of reference current the circuit operates without any distortion. The design includes the simulation of any bifurcation within the intended operation range by using PSpice, Multisim and EWB software. The inductor current output waveforms obtained and compared at different levels of reference currents. There are few ways to improve the output waveforms such as connecting freewheeling diode with parallel to inductor, using combination of triple input/triple output Current Mode Controlled converter or just using parallel input/series output configuration. Parallel-input / paralleloutput are the most common configuration that can be used in current mode control DC-DC converters. Simulation and calculation results shows that capacitor voltage ripple factor reduced from 30% to 3%(actual) and output current ripple from 20% to 3%. Improvement in this type of converter will open up new applications in datacommunication, telecommunication, power-supply in PC and inside the notebook, industrial automation and so forth. The core of the project work focuses on simulating the entire process and later building the prototype

Stability analysis and control of DC-DC converters using nonlinear methodologies

PhD ThesisSwitched mode DC-DC converters exhibit a variety of complex behaviours in power electronics systems, such as sudden changes in operating region, bifurcation and chaotic operation. These unexpected random-like behaviours lead the converter to function outside of the normal periodic operation, increasing the potential to generate electromagnetic interference degrading conversion efficiency and in the worst-case scenario a loss of control leading to catastrophic failure. The rapidly growing market for switched mode power DC-DC converters demands more functionality at lower cost. In order to achieve this, DC-DC converters must operate reliably at all load conditions including boundary conditions. Over the last decade researchers have focused on these boundary conditions as well as nonlinear phenomena in power switching converters, leading to different theoretical and analytical approaches. However, the most interesting results are based on abstract mathematical forms, which cannot be directly applied to the design of practical systems for industrial applications. In this thesis, an analytic methodology for DC-DC converters is used to fully determine the inherent nonlinear dynamics. System stability can be indicated by the derived Monodromy matrix which includes comprehensive information concerning converter parameters and the control loop. This methodology can be applied in further stability analysis, such as of the influence of parasitic parameters or the effect of constant power load, and can furthermore be extended to interleaved operating converters to study the interaction effect of switching operations. From this analysis, advanced control algorithms are also developed to guarantee the satisfactory performance of the converter, avoiding nonlinear behaviours such as fast- and slowscale bifurcations. The numerical and analytical results validate the theoretical analysis, and experimental results with an interleaved boost converter verify the effectiveness of the proposed approach.Engineering and Physical Sciences Research Council (EPSRC), China Scholarship Council (CSC), and school of Electrical and Electronic Engineerin

100 kW Three-Phase Wireless Charger for EV: Experimental Validation Adopting Opposition Method

This paper presents the experimental validation, using the opposition method, of a high-power three-phase Wireless-Power-Transfer (WPT) system for automotive applications. The systemunder test consists of three coils with circular sector shape overlapped to minimize the mutualcross-coupling, a three-phase inverter at primary side and a three-phase rectifier at receiver side.In fact thanks to the delta configuration used to connect the coils of the electromagnetic structure,a three-phase Silicon Carbide (SiC) inverter is driving the transmitter side. The resonance tankcapacitors are placed outside of the delta configuration reducing in this way their voltage sizing. ThisWPT system is used as a 100 kW–85 kHz ultrafast battery charger for light delivery vehicle directlysupplied by the power grid of tramways. The adopted test-bench for the WPT charger consistsof adding circulating boost converter to the system under test to perform the opposition methodtechnique. The experimental results prove the effectiveness of the proposed structure together withthe validation of fully exploited simulation analysis. This is demonstrated by transferring 100 kWwith more than94Ü-to-DC efficiency over 50 mm air gap in aligned conditions. Furthermore,testing of Zero-Current and Zero-Voltage commutations are performed to test the performance of SiCtechnology employed

Sensorless control of the charging process of a dynamic inductive power transfer system with interleaved nine-phase boost converter

The paper proposes a technique for the control of the charging process in a dynamic inductive power transfer system for automotive applications. This technique is based on an impedance control loop on the receiver side. The proposed control allows to carry out the different phases of the charging process in absence of a communication link between ground and vehicle side. The charging process starts with a sensorless procedure for the identification of the actual presence of the vehicle over the receiver. The same control technique introduces several advantages in terms of interoperability between systems having different requirements in terms of power demand. A 11 kW prototype has been implemented based on a transmitter 1.5 meters long as compromise solution between the long track coil and the lumped one. The power management of the receiver side is provided by a nine-phase interleaved boost converter. The experimental results prove the effectiveness of the proposed control together with a good matching with the developed theoretical equations set for the system description

Mitigation of low-frequency current ripple in fuel-cell inverter systems through waveform control

published_or_final_versio

APPLICATION OF BIFURCATION THEORY TO CURRENT MODE CONTROLLED PARALLEL-CONNECTED BOOST DC-DC CONVERTERS

This project is to design a circuit which will guarantee stable operation at switching frequencies, and any quasi-periodic or chaotic operation is regarded as being undesirable and should be avoided. This project focuses in particular on the application of bifurcation theory to parallel-input / parallel-output two-module current-programmed DC-DC converters. Besides, this project describes the operation of Current Mode Controlled Parallel-Connected Boost DC-DC Converters and basically defines chaos, bifurcation and quasi-periodic distortion of the circuit by varying the reference current and comparing it with inductor output current. Within specific ranges of reference current the circuit operates without any distortion. The design includes the simulation of any bifurcation within the intended operation range by using PSpice, Multisim and EWB software. The inductor current output waveforms obtained and compared at different levels of reference currents. There are few ways to improve the output waveforms such as connecting freewheeling diode with parallel to inductor, using combination of triple input/triple output Current Mode Controlled converter or just using parallel input/series output configuration. Parallel-input / paralleloutput are the most common configuration that can be used in current mode control DC-DC converters. Simulation and calculation results shows that capacitor voltage ripple factor reduced from 30% to 3%(actual) and output current ripple from 20% to 3%. Improvement in this type of converter will open up new applications in datacommunication, telecommunication, power-supply in PC and inside the notebook, industrial automation and so forth. The core of the project work focuses on simulating the entire process and later building the prototype

LYAPUNOV FUNCTION-BASED STABILIZING CONTROL SCHEME FOR WIRELESS POWER TRANSFER SYSTEMS WITH LCC COMPENSATION NETWORK

A stabilizing control scheme based on a Lyapunov function is proposed for wireless power transfer (or WPT) systems. A state-space model of the WPT system is developed and the Lyapunov function is formulated based on an energy equation of the system involving state variables. The internal resistance of a battery varies during charge and discharge. Therefore, if a WPT system is used to charge a battery, its output load will vary. Furthermore, the coupling coefficient between the transmitter (primary) and receiver (secondary) coils decreases when they are misaligned. Comparative case studies are conducted to verify the efficacy of the proposed controller in maintaining stability of the WPT system under load variation and acute misalignment of transmitter and receiver coils

Advances in Control of Power Electronic Converters

This book proposes a list of contributions in the field of control of power electronics converters for different topologies: DC-DC, DC-AC and AC-DC. It particularly focuses on the use of different advanced control techniques with the aim of improving the performances, flexibility and efficiency in the context of several operation conditions. Sliding mode control, fuzzy logic based control, dead time compensation and optimal linear control are among the techniques developed in the special issue. Simulation and experimental results are provided by the authors to validate the proposed control strategies

Cost Effective, Highly Efficient Wireless Power Transfer Systems for EV Battery Charging

The impact of changing inner diameter of wireless power transfer (WPT) coils on coupling coefficient is studied. It is demonstrated that at a certain outer and inner coil diameter, turn space variation has minor effect on the coupling coefficient. Next, two compensation networks, namely primary LCC and secondary LCC, which offer load-independent voltage transfer ratio and zero voltage switching for WPT, are presented. For both compensation networks, the condition for having zero voltage switching operation are derived. In addition, load-independent voltage transfer ratio (VTR) frequencies are obtained and VTR at each frequency is derived. Then, required equations for calculation of WPT system efficiency based on its equivalent circuit are presented. Eventually, by defining a time-weighted transfer average efficiency (TWTAE), and based on measured values of resistance and inductance of a WPT prototype and experimental charging curve of a Li-ion battery, a design procedure for both compensation networks is proposed. The proposed design leads to high TWTAE as well as low material usage. Simulation and experimental results verify the superiority of proposed coil and compensation design compared to conventional one

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters