Battery Charge Applications Based on Wide Output Voltage Range

In this study, high efficiency design procedure of a phase shifted full bridge (PSFB) converter is presented for on-board electrical vehicle (EV) battery charger. Presented design methodology used lithium-ion battery cells because of their high voltage and current rates compared to a lead-acid battery cells. In this case, PSFB converter can be regulated wide range output voltage with while its soft switching operation is maintained. The basic operation principles of PSFB converter is defined and its soft switching operation requirements are given. To evaluate the performance of the converter over wide output voltage range, zero voltage switching (ZVS) operation of converter is discussed based on dead time requirement. To improve efficiency, the snubber inductance effects on soft switching over wide output voltage range are evaluated. Finally, operation of the PSFB converter is validated experimentally with a prototype which has 42-54 V/15 A output range at 200 kHz switching frequency

LLC resonant charger with variable inductor control

The present work pretends to study the operation and behavior of the LLC resonant converter topology considering a battery charging application, using the traditional switching frequency control and a new control variable, the variable inductance, provided by a current controlled device, the Variable Inductor (VI). During this work, a brief state of the art regarding general types of power converters and resonant power converters is presented. The LLC resonant converter topology and its advantages and disadvantages are described. The VI principle of operation and structure is presented and discussed and, in the end some information about batteries and its behavior under charging and discharging conditions is presented. The considered batteries characteristics for the studied battery charger are shown and the adopted charging profile is presented. In the following chapters, a theoretical analysis of the LLC resonant converter operation and behavior under switching frequency or VI control is performed and presented. A design methodology is proposed for the converter considering both switching frequency and VI control, separately or simultaneously. Simulations of the converter operation under open-loop condition were made, and simulation results were obtained and discussed. A prototype was built and test results were obtained. The prototype uses a SiC MOSFET (Silicon Carbide Metal Oxide-Semiconductor Field Effect Transistor) based inverter working at 100 kHz controlled with fiber optic drivers. To build the prototype, Printed Circuit Boards (PCB) were designed, manufactured and built. An high-frequency transformer and a VI were also design and built. Finally, theoretical, simulation and experimental results are confronted in order to reach conclusions regarding to the proposed design methodology and the prototype operation. This final analysis allows validating the LLC-VI resonant converter as a good option for a battery charger

Elektrikli araç yerleşik batarya şarj uygulamaları için yüksek verimli bir LLC rezonanslı DC-DC dönüştürücünün tasarım yaklaşımı

In this study, an optimal design procedure of inductor-inductor-capacitor (LLC) resonant converter for on-board electrical vehicle (EV) battery charge applications based on high efficiency is proposed. In the design procedure, lithium-ion battery cells are used due to their high power density, higher voltage and current rates compared to a lead-acid battery cells. Thus, LLC resonant converter should be regulated the output voltage in a wide voltage range with different load conditions according to typical charging profile of lithium-ion battery. For the design procedure, basic operation characteristics of LLC resonant converter is defined and operation regions are discussed in terms of high efficiency. The operation regions of LLC resonant converter are discussed to regulate wide output voltage range. In order to reach high efficiency optimal design, efficiency calculations based on Saber simulation are extracted for discussed operation regions. The best efficiency values are obtained for the operation of above-below resonance. Finally, soft switching operation of the LLC resonant converter is validated by Saber simulation for wide output voltage range and with changing load current

Optimal design of line level control resonant converters in plug‐in hybrid electric vehicle battery chargers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163784/1/els2bf00015.pd

Analysis of CLL voltage-output resonant converters using describing functions

A new ac equivalent circuit for the CLL voltage output resonant converter is presented, that offers improved accuracy compared with traditional FMA-based techniques. By employing describing function techniques, the nonlinear interaction of the parallel inductor, rectifier and load is replaced by a complex impedance, thereby facilitating the use of ac equivalent circuit analysis methodologies. Moreover, both continuous and discontinuous rectifier-current operating conditions are addressed. A generic normalized analysis of the converter is also presented. To further aid the designer, error maps are used to demonstrate the boundaries for providing accurate behavioral predictions. A comparison of theoretical results with those from simulation studies and experimental measurements from a prototype converter, are also included as a means of clarifying the benefits of the proposed techniques

Energy-efficient and Power-dense DC-DC Converters in Data Center and Electric Vehicle Applications Using Wide Bandgap Devices

The ever increasing demands in the energy conversion market propel power converters towards high efficiency and high power density. With fast development of data processing capability in the data center, the server will include more processors, memories, chipsets and hard drives than ever, which requires more efficient and compact power converters. Meanwhile, the energy-efficient and power-dense converters for the electric vehicle also result in longer driving range as well as more passengers and cargo capacities. DC-DC converters are indispensable power stages for both applications. In order to address the efficiency and density requirements of the DC-DC converters in these applications, several related research topics are discussed in this dissertation. For the DC-DC converter in the data center application, a LLC resonant converter based on the newly emerged GaN devices is developed to improve the efficiency over the traditional Si-based converter. The relationship between the critical device parameters and converter loss is established. A new perspective of extra winding loss due to the asymmetrical primary and secondary side current in LLC resonant converter is proposed. The extra winding loss is related to the critical device parameters as well. The GaN device benefits on device loss and transformer winding loss is analyzed. An improved LLC resonant converter design method considering the device loss and transformer winding loss is proposed. For the DC-DC converter in the electric vehicle application, an integrated DC-DC converter that combines the on-board charger DC-DC converter and drivetrain DC-DC converter is developed. The integrated DC-DC converter is considered to operate in different modes. The existing dual active bridge (DAB) DC-DC converter originally designed for the charger is proposed to operate in the drivetrain mode to improve the efficiency at the light load and high voltage step-up ratio conditions of the traditional drivetrain DC-DC converter. Design method and loss model are proposed for the integrated converter in the drivetrain mode. A scaled-down integrated DC-DC converter prototype is developed to verify the design and loss model

Iterative Design of a 60 kW All-Si Modular LLC Converter for Electric Vehicle Ultra-Fast Charging

This paper proposes an iterative design procedure for a high-power LLC resonant converter, taking part in a 60 kW modular DC/DC conversion stage for an electric vehicle (EV) ultra-fast battery charger. The basics of operation of the LLC converter are briefly recalled and the most relevant analytical expressions are reported. Due to the high-power requirement and the wide output battery voltage range (i.e. 250-1000 V), a modular design approach is adopted, leveraging the split input DC-link structure provided by a 3-level active front-end. A total of four modules, with at 15 kW nominal power and a 250-500 V output voltage regulation capability, are designed with a straightforward iterative procedure based on the first-harmonic approximation (FHA). Finally, the proposed methodology is verified experimentally on a 15 kW LLC converter prototype directly resulting from the design procedure

A High Frequency, High Efficiency, High Power Factor Isolated On-board Battery Charger for Electric Vehicles

In this paper, a high frequency, high efficiency and high power factor isolated on-board battery charger is proposed. The proposed topology includes two parts, AC/DC power factor correction (PFC) circuit unit and DC/DC converter unit. For the PFC circuit, SiC based totem-pole interleaved bridgeless PFC is selected, the diode bridge rectifier is eliminated. In addition, it can operate in continuous conduction mode (CCM) thanks to the low reverse recovery losses of the SiC MOSFETs. Besides, the interleaved technology minimizes the input current ripple. The DC/DC converter unit is composed of two LLC resonant converters sharing the same full-bridge inverter with constant switching frequency. The outputs of two LLC resonant converters are connected in series. One of the LLC resonant converter is operating at the resonant frequency, which is the highest efficiency operation point; while magnetic control is adopted for the second LLC resonant converter to fulfill the duty of providing closed-loop control for constant voltage (CV) and constant current (CC) charge modes. The proposed topology can achieve zero voltage switching (ZVS) for all primary switches and zero current switching (ZCS) for all secondary diodes during both CC and CV modes. Furthermore, the constant switching frequency is simplified the electromagnetic interference (EMI) filter design. Simulation studies for 3.3kW power level and 100kHz switching frequency are performed, the simulation results are presented to verify the feasibility and validity of the proposed topology

Multi-objective optimization of power electronic converters

L'abstract è presente nell'allegato / the abstract is in the attachmen

Study of a Symmetrical LLC Dual-Active Bridge Resonant Converter Topology for Battery Storage Systems

A symmetrical LLC resonant converter topology with a fixed-frequency quasi-triple phase-shift modulation method is proposed for battery-powered electric traction systems with extensions to other battery storage systems. Operation of the converter with these methods yields two unique transfer characteristics and is dependent on the switching frequency. The converter exhibits several desirable features: 1) load-independent buck-boost voltage conversion when operated at the low-impedance resonant frequency, allowing for dc-link voltage regulation, zero-voltage switching across a wide load range, and intrinsic load transient resilience; 2) power flow control when operated outside the low-impedance resonance for integrated battery charging; 3) and simple operational mode selection based on needed functionality with only a single control variable per mode. Derivation of the transfer characteristics for three operation cases using exponential Fourier series coefficients is presented. Pre-design evaluation of the S-LLC converter is presented using these analytical methods and corroborated through simulation. Furthermore, the construction of a rapid-prototyping magnetics design tool developed for high-frequency transformer designs inclusive of leakage inductance, which is leveraged to create the magnetic elements needed for this work. Two 2kW prototypes of the proposed topology are constructed to validate the analysis, with one prototype having a transformer incorporating the series resonant inductance and secondary clamp inductance into the transformer leakage and magnetizing inductance, respectively. A test bench is presented to validate the analysis methods and proposed multi-operational control scheme. Theoretical and experimental results are compared, thus demonstrating the feasibility of the new multi-mode operation scheme of the S-LLC converter topology