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Battery energy storage system (BESS) is promising to be implemented in residential applications for supporting PV integration, load shifting, and backup power purposes. For this application, 48V second-life battery draws more and more attentions for their cost-effectiveness, safe voltage level, reliability, and potential large market. This thesis proposes the comprehensive control and design of an isolated battery-driven grid interface (IBDGI) with the dual-active-bridge (DAB) converter for residential applications with 48V battery pack. The three-phase DAB converter is a promising candidate as the front-end DC/DC converter in the two-stage IBDGI due to its high efficiency, high power density, and low capacitance requirement. An effective design strategy for the three-phase DAB converter is proposed based on the zero-voltage-switching (ZVS) zone and back-ow power to achieve high efficiency for a wide operating voltage range and different load conditions. Based on the power loss model, an easily-implemented variable switching frequency operating method is proposed to further increase the efficiency at light load conditions. The dead-time effect is observed in the three-phase DAB converter. To avoid the dead-time effect and better understand the phenomena, a comprehensive analysis is proposed. All the cases of the dead-time effect in the three-phase DAB converter are analyzed in terms of the buck, boost, and matching states. The expressions of the transmission power, constraint conditions, and key time of the dead-time effect are derived for each state. The operation waveforms of the dead-time effect are also presented. The hybrid capacitor bank composed by the LC resonant lter with electrolytic capacitor and lm capacitor is utilized for the DC bus of the IBGDI. The electrolytic capacitors work as passive decoupling purpose while the lm capacitor is responsible for high switching harmonic ltering. Moreover, a current sharing method between the hybrid capacitor bank is proposed to extend the electrolytic capacitor's life. The LCL single-phase inverter is applied for the downstream of the IBDGI. A step-by-step design procedure of the LCL lter with passive damping is proposed for the 120V/240V dual grid-tied and standalone modes. The PR controllers are also designed for the LCL inverter for standalone and grid-tied modes. At the system level, a novel second harmonic current (SHC) reduction strategy is proposed for the IBDGI with the three-phase DAB converter by adding a load current feedforward (LCFF) path to the DAB voltage closed-loop controller. This method will suppress the SHC without modi cations of the original controller's bandwidth, which make it easy to be implemented. The small-signal model of the three-phase DAB converter is provided and veri ed by the step response. The parameter sensitivity analysis for the LCFF method is proposed to show that the SHC is well suppressed within ±20% parameter error. The proposed converter and control methods are veri ed by simulation and experimental results. / Thesis / Doctor of Philosophy (PhD)

Rapid expansion of the information technology (IT) sector, market size and consumer interest for off-line power supply continue to rise, particularly for computers, flat-panel TVs, servers, telecom, and datacenter applications. Normal components of an off-line power supply include an electromagnetic interference (EMI) filter, a power factor correction (PFC) circuit, and an isolated DC-DC converter. For off-line power supply, an isolated DC-DC converter offers isolation and output voltage adjustment. For an off-line power supply, it takes up significantly more room than the rest; thus, an isolated DC-DC converter is essential for enhancing the overall performance and lowering the total cost of an off-line power supply. In contrast, data center server power supplies are the most performance-driven, energy-efficient, and cost-aware of any industrial application power supply. The full extent of data centers' energy consumption is coming into focus. By 2030, it is anticipated that data centers will require around 30,000 TWh, or 7.6% of world power usage. In addition, with the rise of cloud computing and big data, the energy consumption of data centers is anticipated to continue rising rapidly in the near future. In data centers, isolated DC-DC converters are expected to supply even higher power levels without expanding their size and with much greater efficiency than the present standard, which makes their design even more challenging. LLC resonant converters are frequently utilized as DC-DC converters in off-line power supply and data centers because of their high efficiency and hold-up capabilities. LLC converters may reduce electromagnetic interference because the primary switches and secondary synchronous rectifiers (SRs) both feature zero-voltage-switching (ZVS) and zero-current-switching (ZCS) for the SRs. Almost every state-of-the-art off-line power supply uses LLC converters in their DC-DC transformations. However, LLC converters face three important challenges. First, the excessive core loss caused by the uneven flux distribution in planar magnetics, owing to the huge size and high-frequency operation of the core. These factors led to the observation of dimensional resonance within the core and an excessive amount of eddy current circulating within the core, which resulted in the generation of high eddy loss within the ferrite material. This was normally assumed to be negligible for small core sizes and lower frequencies. This dissertation proposes methods to help redistribute the flux in the core, particularly in the plates where the majority of core losses are concentrated, and to provide more paths for the flux to flow so that the plates' thickness can effectively be reduced by half and core losses, particularly eddy loss, are reduced significantly. Second, the majority of power supplies in the IT sector are needed to deliver high-current output, but the transformer is cumbersome and difficult to build because of its high conduction losses. In addition, establishing a modular solution that can be scaled up to greater power levels while attaining a superior performance relative to best practices is quite difficult. By increasing the switching frequency to several hundred kilohertz using wide-band-gap (WBG) transistors, printed circuit board (PCB) windings may include magnetics. This dissertation offers a modular and scalable matrix transformer structure and its design technique, allowing any number of elemental transformers to be integrated into a single magnetic core with significantly reduced winding loss and core loss. It has been shown that the ideal power limitations per transformer for PCB-based magnetics beat the typical litz wire design in all design areas, in addition to the unique advantages of PCB-magnetics, such as their low profile, high density, simplicity, and automated construction. Alternatively, shielding layers may be automatically put into the PCB windings between the main and secondary windings during the production process to reduce CM noise. A method of shielding is presented to reduce CM noise. The suggested transformer design and shielding method are used in the construction of a 3 kW 400V/48 V LLC converter, with a maximum efficiency of 99.06% and power density of 530W/in3. Thirdly, LLC converters with a matrix transformer encounter a hurdle for extending greater power, including the number of transformers needed and the magnetic size. In addition to the necessity of resonant inductors, which increase the complexity and size of the magnetic structure, there is a need for a resonant inductor. By interconnecting the three-phases in a certain manner, three-phase interleaved LLC converters may lower the circulating energy, but they have large and numerous magnetic components. In this dissertation, a new topology for three-phase LLC resonant converters is proposed. Three-phase systems have the advantage of flux cancellation, which may be used to further simplify the magnetic structure and decrease core loss. In addition, a study of the various three-phase topologies is offered, and a criterion for selecting the best suitable topology is shown. Compared to the single-phase LLC, the suggested topology has less winding loss and core loss. In addition, three-phase transformers have a lower volt-second rating, and smaller core sizes may be used to mitigate the impact of eddy loss in the ferrite material. In contrast, three-phase systems offer superior EMI performance, which is shown in the loss and size of the EMI filter, and much less output voltage ripple, which is reflected in the size of the output filter. Finally, several methods of integrating resonant inductors into transformer magnetics are presented in order to accomplish a simple, compact, and cost-effective magnetic architecture. By increasing the switching frequency to 500 kHz, all six transformers and six inductors may be achieved using four-layer PCB winding. To decrease CM noise, additional 2-layer shielding may be implemented. A 500 kHz, 6-8 kW, 400V/48V, three-phase LLC converter with the suggested magnetic structure achieves 99.1% maximum efficiency and a power density of 1000 W/in3. This dissertation addresses the issues of analysis, magnetic design, expansion to higher power levels, and electromagnetic interference (EMI) in high-frequency DC/DC converters used in off-line power supply and data centers. WBG devices may be effectively used to enable high-frequency DC/DC converters with a hundred kilohertz switching frequency to achieve high efficiency, high power density, simple yet high-performance, and automated manufacture. Costs will be minimized, and performance will be considerably enhanced. / Doctor of Philosophy / The IT industry, market size, and customer interest in off-line power supply continue to grow quickly, especially for computers, flat-panel TVs, servers, telecom, and datacenter applications. Off-line power supplies usually have a DC-DC converter, an EMI filter, and a PFC circuit. A DC-DC converter is needed for an off-line power supply. An isolated DC-DC converter makes an off-line power supply work better and cost less, even though it takes up more space than the rest. But power supplies for data center servers are the most performance-driven, energy-efficient, and cost-conscious industrial applications. It's becoming clear how much energy data centers use. By 2030, data centers will use 7.6% of the world's power, or 30,000 TWh. With the rise of cloud computing and big data, energy use in data centers is likely to go up by a lot. In data centers, isolated DC-DC converters are expected to have much more power without getting bigger and to be much more efficient than the current standard. This makes their design even harder. LLC resonant converters are often used as DC-DC converters in data centers and off-line power supplies because they are very efficient and easy to control. LLC converters may have less electromagnetic interference because both the primary switches and the secondary synchronous rectifiers (SRs) have zero-voltage-switching (ZVS) and zero-current-switching (ZCS). Almost every modern off-line power supply uses LLC converters for DC-DC stage. LLC converters have to deal with three big problems. Due to the large size of the core and the high frequency of operation, the uneven distribution of flux in planar magnetics causes too much core loss. This dissertation suggests ways to redistribute flux in the core, especially in the plates where most core losses are concentrated and provide more flux paths to reduce plate thickness by half and core losses, especially eddy loss. Second, most IT power supplies need to put out a lot of current, but transformers are bulky and hard to build because they lose a lot of current. It is hard to make a modular solution that can scale up to higher levels of power and perform better than best practices. With wide-band-gap (WBG) transistors, the switching frequency can be raised to several hundred kilohertz so that magnetics can be added to PCB windings. This dissertation describes a modular and scalable matrix transformer structure and design method that lets any number of elemental transformers be put into a single magnetic core with much less winding loss and core loss. PCB-based magnetics have a low profile, a high density, are easy to build, and can be built automatically. Their ideal power limits per transformer beat the typical litz wire design in every way. Shielding layers can be added automatically between the main and secondary PCB windings to cut down on CM noise. CM noise is lessened by shielding. The suggested transformer design and shielding method are used to build a 3 kW 400V/48 V LLC converter with a maximum efficiency of 99.06% and a power density of 530W/in3. Third, LLC converters with matrix transformers can't get more power without more transformers and a bigger magnetic size. Resonant inductors, which add to the size and complexity of a magnetic structure, are also needed. By connecting the three phases, three-phase interleaved LLC converters use less energy, but they have a lot of magnetic parts. In this paper, a three-phase LLC resonant converter topology is proposed. In three-phase systems, flux cancellation makes magnetic structures easier to understand and reduces core loss. There is also a study of three-phase topologies and a set of criteria for choosing one. Compared to the single-phase LLC, the topology cuts down on winding and core loss. Three-phase transformers have a lower volt-second rating, and ferrite material eddy loss can be reduced by making the core smaller. The size and loss of the EMI filter show that three-phase systems have less output voltage ripple and better EMI performance. Finally, several ways of putting resonant inductors into the magnetics of a transformer are shown to make a magnetic architecture that is simple, small, and cheap. At 500 kHz, all six transformers and all six inductors can be wound on a four-layer PCB. CM noise can be cut down with 2-layer shielding. With the suggested magnetic structure, a 500 kHz, 6-8 kW, 400V/48V, three-phase LLC converter can reach 99.1% maximum efficiency and 1000 W/in3. This dissertation presents analysis, magnetic design, expanding to higher power levels, and electromagnetic interference (EMI) in high-frequency DC/DC converters used in off-line power supplies and data centers. WBG devices can be used to make high-frequency DC/DC converters with a switching frequency of a few hundred kilohertz that are powerful, easy to use, and can be automated. Both cost and performance will get better.

General-purpose step-down converter is essential in electronic system for processing energy from high-voltage rail to low-voltage circuits. The applications can be found at the auxiliary supplies in automobile, industrial and communication systems. Buck converter is a common circuit topology to fulfill step-down conversion, especially in low-power application since it is well-studied and straightforward. However, it suffers from low duty cycle under high step-down condition, and typically operates in continuous conduction mode (CCM) that generates large switching loss. On the other hand, as an extension of the buck converter, tapped-inductor (TI) buck converter has larger duty cycle while maintaining the structural simplicity. Therefore, the main objective of this thesis is to explore the potential of TI buck converter as a wide conversion range, high power density and high efficiency topology for low power application. To achieve high efficiency at switching frequency of MHz-level, synchronous conduction mode (SCM) is applied for turn-on losses elimination. The operation principle and power stage design of SCM TI buck is first introduced. The design of high switching frequency coupled inductor is emphasized since its size plays a critical role in power density. Loss breakdown is also provided to perform a comprehensive topological study. Secondly, detailed zero-voltage-switching (ZVS) condition of SCM TI buck is derived so that the converter does not experience redundant circulating energy. The experimental results of 15-W SCM TI buck converter prototypes are provided with 90.7% of peak power stage efficiency. The size of coupled inductor is down to 116 mm3. To enhance light-load efficiency, a variable frequency control scheme based on derived ZVS conditions is implemented with the switching frequency ranging from 2 MHz to 2.9 MHz. / Master of Science / General-purpose step-down converter is essential in electronic system for processing energy from high-voltage rail to low-voltage circuits. The applications can be found at the auxiliary supplies in automobile, industrial and communication systems. Typically, the ultimate goals of general-purpose step-down converter are versatility, high efficiency and compact size. Recently, tapped-inductor (TI) buck converter is studied since it could overcome the drawback of commonly used buck converter under high step-down conversion. Therefore, the potential of TI buck converter as a general-purpose step-down converter candidate is explored in this thesis, including control method, hardware design, etc. The thesis verifies that TI buck converter could have compact size while remaining efficient and adaptable.

The demand for increased renewable energy production has led to increased photovoltaic (PV) installations worldwide. As this demand continues to grow, it is important that the costs of PV installations decrease while the power output capability increases. One of the components in PV installations that has lots of room for improvement is the power conditioning system. The power conditioning system is responsible for converting the power output of PV modules into power useable by the utility grid while insuring the PV array is outputting the maximum available power. Modular power conditioning systems, where each PV module has its own power converter, have been proven to yield higher output power due to their superior maximum power point tracking capabilities. However, this comes with the disadvantages of higher costs and lower power conversion efficiencies due to the increased number of power electronics converters. The primary objective of this dissertation is to develop a high-efficiency, low cost microconverter in an effort to increase the output power capability and decrease the cost of modular power conditioning systems. First, existing isolated dc-dc converter topologies are explored and a new topology is proposed based on the highly-efficient series resonant converter operating near the series resonant frequency. Two different hybrid modes of operation are introduced in order to add wide input-voltage regulation capability to the series resonant converter while achieving high efficiency through low circulating currents, zero-current switching (ZCS) of the output diodes, zero-voltage switching (ZVS) and/or ZCS of the primary side active switches, and direct power transfer from the source to the load for the majority of the switching cycle. Each operating mode is analyzed in detail using state-plane trajectory plots. A systematic design approach that is unique to the newly proposed converter is presented along with a detailed loss analysis and loss model. A 300-W microconverter prototype is designed to experimentally validate the analysis and loss model. The converter featured a 97.7% weighted California Energy Commission (CEC) efficiency with a nominal input voltage of 30 V. This is higher than any other reported CEC efficiency for PV microconverters in literature to date. Each operating mode of the proposed converter can be controlled using simple fixed-frequency pulse-width modulation (PWM) based techniques, which makes implementation of control straightforward. Simplified models of each operating mode are derived as well as control-to-input voltage transfer functions. A smooth transition method is then introduced using a two-carrier PWM modulator, which allows the converter to transition between operating modes quickly and smoothly. The performance of the voltage controllers and transition method were verified experimentally. To ensure the proposed converter is compatible with different types of modular power conditioning system architectures, system-level interaction issues associated with different modular applications are explored. The first issue is soft start, which is necessary when the converter is beginning operation with a large capacitive load. A novel soft start method is introduced that allows the converter to start up safely and quickly, even with a short-circuited output. Maximum power point tracking and double line frequency ripple rejection are also explored, both of which are very important to ensuring the PV module is outputting the maximum amount of available power. Lastly, this work deals with efficiency optimization of the proposed converter. It is possible to use magnetic integration so that the resonant inductor can be incorporated into the isolation transformer by way of the transformer leakage inductance in order to reduce parts count and associated costs. This chapter, however, analyzes the disadvantages to this technique, which are increased proximity effect losses resulting in higher conduction losses. A new prototype is designed and tested that utilizes an external resonant inductor and the CEC efficiency was increased from 97.7% to 98.0% with a marginal 1.8% total cost increase. Additionally, a variable frequency efficiency optimization algorithm is proposed which increases the system efficiency under the high-line and low-line input voltage conditions. This algorithm is used for efficiency optimization only and not control, so the previously presented simple fixed-frequency modeling and control techniques can still be utilized. / Ph. D.

Power converters used in high reliability radiation hardened space applications trail their commercial counterparts in terms of power density and efficiency. This is due to the additional challenges that arise in the design of space rated power converters from the harsh environment they need to operate in, to the limited availability of space qualified components and field demonstrated power converter topologies. New radiation hardened Gallium Nitride (GaN) Field Effect Transistors (FETs) with their inherent radiation tolerance and superior performance over Silicon Power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) are a promising alternative to improve power density and performance in space power converters. This thesis presents the considerations and design of a practical implementation of the Phase Shifted Full Bridge DC-DC Isolated converter with synchronous rectification for space applications. Recently released radiation hardened GaN FETs were used in the Full Bridge and synchronous rectifier power stages. A survey outlining the benefits of new radiation hardened GaN FETs for space power applications compared to current radiation hardened power MOSFETs is included. In addition, this work presents the overall design process followed to design the DC-DC converter power stage, as well as a comprehensive power loss analysis. Furthermore, this work includes details to implement a conventional hard-switched Full Bridge DC-DC converter for this application. An efficiency and component stress comparison was performed between the hard-switched Full Bridge design and the Phase Shifted Full Bridge DC-DC converter design. This comparison highlights the benefits of phase shift modulation (PSM) and zero voltage switching (ZVS) for GaN FET applications. Furthermore, different magnetic designs were characterized and compared for efficiency in both converters. The DC-DC converters implemented in this work regulate the output to a nominal 20 V, delivering 500 W from a nominal 100 V DC Bus input. Complete fault analysis and protection circuitry required for a space-qualified implementation is not addressed by this work. / MS / Recently released radiation-hardened Gallium Nitride (GaN) Field Effect Transistors (FETs) offer the opportunity to increase efficiency and power density of space DC-DC power converters. The current state of the art for space DC-DC power conversion trails their commercial counterparts in terms of power density and efficiency. This is mainly due to two factors. The first factor is related to the additional challenges that arise in the design of space rated power converters from the harsh environment they need to operate in, to the limited availability of space qualified components and field demonstrated converter topologies. The second factor lies in producing reliable radiation hardened power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). GaN FETs not only have better electrical performance than power MOSFETs, they have also demonstrated inherent tolerance to radiation. This results in less structural device changes needed to make GaN FETs operate reliably under high radiation compared to their MOSFETs counterparts. This work outlines the design implications of using newly released radiation hardened GaN FETs to implement a fixed frequency isolated Phase Shifted Full Bridge DC-DC converter while strictly abiding to the design constraints found in space-power converter applications. In addition, a one-to-one performance comparison was made between the soft-switched Phase Shift modulated Full Bridge and the conventional hard-switched Full Bridge DC-DC converter. Finally, different magnetic designs were evaluated in the laboratory to assess their impact on converter efficiency.

The battery charger plays an important role in the development of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs).This thesis focuses on the DC-DC converter for high voltage battery charger and is divided into four chapters. The background related to EV battery charger is introduced, and the topologies of isolated DC-DC converter possibly applied in battery charge are sketched in Chapter 1. Since the EV battery charger is high voltage high power, the phase-shifted full bridge and LLC converters, which are popularly used in high power applications, are discussed in detail in Chapter 2. They are generally considered as high efficiency, high power density and high reliability, but their prominent features are also limited in certain range of operation. To make full use of the advantages and to avoid the limitation of the phase-shifted full bridge and LLC converters, a novel hybrid resonant and PWM converter combining resonant LLC half-bridge and phase shifted full-bridge topology is proposed and is described in Chapter 3. The converter achieves high efficiency and true soft switching for the entire operation range, which is very important for high voltage EV battery charger application. A 3.4 kW hardware prototype has been designed, implemented and tested to verify that the proposed hybrid converter truly avoids the disadvantages of LLC and phase-shifted full bridge converters while maintaining their advantages. In this proposed hybrid converter, the utilization efficiency of the auxiliary transformer is not that ideal. When the duty cycle is large, LLC converter charges one of the capacitors but the energy stored in the capacitor has no chance to be transferred to the output, resulting in the low utilization efficiency of the auxiliary transformer. To utilize the auxiliary transformer fully while keeping all the prominent features of the previous hybrid converter in Chapter 3, an improved hybrid resonant and PWM converter is proposed in Chapter 4. The idea has been verified with simulations. The last chapter is the conclusion which summaries the key features and findings of the two proposed hybrid converters. / Master of Science

This work explores the design, simulation, construction, and analysis of a novel Non-isolated DC-DC Buck-Boost converter which has the advantage of incorporating a low-side switch compared to the traditional buck-boost which requires a high-side switch. This allows the use of a low-side driver which further simplifies the design and operation of the converter. The proposed Buck-Boost converter was constructed to provide -24 V output from an input range of 12V-18V with 15V nominal input at 10W maximum output power utilizing 500kHz switching frequency. Findings from simulations and hardware tests verify that the converter effectively provides the desired -24 V output at varying loads with less than 3% ripple. At the nominal input voltage, the efficiency of the converter reaches 82.37% at full load and peak efficiency of 88.5% at 20% load. Moreover, the input voltage ripple of the proposed non-isolated converter reached 8.4% at full load, due to the pulsating nature of the input current. Overall, results verify the feasibility of the proposed non-isolated Buck-Boost converter as an alternative solution for the conventional buck-boost with the advantage of a low side switch while maintaining a low component count.

Hysteresis current control has been widely used in power electronics with the advantages of fast dynamic response under parameter, line and load variation and ensured stability. However, a main disadvantage of hysteresis current control is the uncertain and varying switching frequency which makes it difficult to form an average-value model. The changing switching frequency and unspecified switching duty cycle make conventional average-value models based on PWM control difficult to apply directly to converters that are controlled by hysteresis current control. In this work, a new method for average-value modeling of hysteresis current control in boost converters, three-phase inverters, and brushless dc motor drives is proposed. It incorporates a slew-rate limitation on the inductor current that occurs naturally in the circuit during large system transients. This new method is compared with existing methods in terms of simulation run time and rms error. The performance is evaluated based on a variety of scenarios, and the simulation results are compared with the results of detailed models. The simulation results show that the proposed model represents the detailed model well and is faster and more accurate than existing methods. The slew-rate limitation model of hysteresis current control accurately captures the salient detail of converter performance while maintaining the computational efficiency of average-value models. Validations in hardware are also presented.

The telecommunications market is one of the large rapidly growing fields in today’s power supply industry due to the increasing demand for telecom distributed power supply (DPS) systems. The half-bridge LLC (Inductor-Inductor-Capacitor) resonant converter is currently the most attractive topology for the design and implementation of 24V/48V DC telecom power converters. The current doubler rectifier (CDR) converter topology was invented and described in the early 1950s which can offer the unique characteristic of halving the output voltage while doubling the output current compared to a standard rectifier. In this thesis, the current doubler converter topology with its unique characteristic is evaluated as a complementary solution to improve the LLC resonant converter performance, especially for the low output voltage and high output current telecommunication applications. A novel half-bridge LLC resonant current doubler converter (LLC-CDR) is proposed in this thesis which can offer several performance benefits compared to conventional LLC-standard rectifier design . The unique characteristics of the LLC-CDR topology can offer significant improvements by transformation of a 48V converter into a 24V converter with the same power density. This thesis introduces a new SPICE-based simulation model to analyse the operation of this novel LLC-CDR converter circuit design. This model can be used to define the critical component parameters for the LLC -CDR circuit output inductor values. It can also be used to predict the circuit overall performance under different load conditions. Both time-domain based transient simulation analysis and frequency-domain based AC analysis provided by this simulation model showed favourable results in comparison to bench measurement results on a prototype. The model provides a valuable insight to reveal some of the unique characteristics of this LLC -CDR topology. It demonstrates a proof of concept that the conventional LLC resonant converter can be easily redesigned for low voltage, high current applications by using the LLC-CDR topology without requiring a new design for the LLC resonant stage components and the power transformer. A new magnetic integration solution was proposed to significantly improve the overall performance in the LLC-CDR topology that had not been published before. The LLC-CDR converter hardware prototypes with two output inductors coupled and uncoupled configurations were extensively modelled, constructed and bench tested.Test results demonstrated the suitability of an integrated coupled inductors design for the novel LLC-CDR converter application. The integrated coupled inductors design can significantly improve the LLC-CDR converter frequency-domain based AC simulation analysis results. In addition, these results also illustrate the potential benefit of how the magnetic integration design in general could reduce the magnetic component size, cost, and weight compared to the uncoupled inductors design. Finally, a hardware prototype circuit was constructed based on a commercial 1800 W single phase telecom power converter to verify the operation of this novel half bridge LLC-CDR topology. The converter prototype successfully operated at both no load and full load conditions with the nominal output voltage halved from 48VDC to 24VDC, and doubled the output current to match the same output power density. It also demonstrates that the efficiency of this novel half bridge LLC –CDR is 92% compares to 90% of EATON’s commercial 24VDC LLC resonant converter, which can fulfill the research goals.