Dong-Myoung Joo

On the Feasibility of Integrated Battery Charger Utilizing Traction Motor and Inverter in Plug-In Hybrid Electric Vehicles

For the practical use of an integrated battery charger (IBC), this paper proposes an improved IBC based on a detailed analysis of the conventional IBC with respect to the inherent limitations such as switching frequency, motor inductance, common-mode noise, power loss, and input current and voltage sensing. Moreover, battery charging performance according to pulse-width-modulated switching schemes is mathematically analyzed and explained. The informative simulation and experimental results are provided with the traction motor/inverter hardware of an actual plug-in hybrid vehicle.

DCM Frequency Control Algorithm for Multi-Phase DC-DC Boost Converters for Input Current Ripple Reduction

In this paper, a discontinuous conduction mode (DCM) frequency control algorithm is proposed to reduce the input current ripple of a multi-phase interleaved boost converter. Unlike conventional variable duty and constant frequency control, the proposed algorithm controls the switching frequency to regulate the output voltage. By fixing the duty ratio at 1/N in the N-phase interleaved boost converter, the input current ripple can be minimized by ripple cancellation. Furthermore, the negative effects of the diode reverse recovery current are eliminated because of the DCM characteristic. A frequency controller is designed to employ the proposed algorithm considering the magnetic permeability change. The proposed algorithm is analyzed in the frequency domain and verified by a 600 W three-phase boost converter prototype that achieved 57% ripple current reduction.

Design and Implementation of 150W Portable Fuel Cell Power Pack

Existing energy sources convert chemical energy into mechanical energy, while fuel cell directly generates electricity through an electrochemical reaction between hydrogen and oxygen. Therefore, it has a lot of strong points such as high efficiency, zero emission, and etc. In addition, with the development of hydrogen preservation technique, some companies have been researching and releasing portable fuel cell power packs for specific applications like military equipment, automobile, and so on. However, there are some drawbacks to the fuel cell, high cost and slow dynamic response. In order to compensate these weak points, auxiliary energy storages could be applied to the fuel cell system. In this paper, the optimum structure for a 150W portable fuel cell power pack with a battery pack is selected considering the specification of the system, and the design process of main parts is described in detail. Here, main objectives are compact size, simple control, high efficiency, and low cost. Then, an automatic mode change algorithm, which converts the operating mode depending on the states of fuel cell stack, battery pack, and load, is introduced. Finally, performance of the designed prototype using the automatic mode change control is verified through experiments.

Design and control of inductive power transfer system for electric vehicles considering wide variation of output voltage and coupling coefficient

In this paper, a design and control of the inductive power transfer (IPT) system for electric vehicles are proposed considering wide variation of output voltage and coupling coefficient. The characteristics of the proposed system and a design method of the resonant network are also suggested. By utilizing the battery management converter at the final stage of the system, the design and control can be simplified while managing the output voltage and power of the battery. The 3.3kW laboratory prototype with magnetic power pads are manufactured and the validity of the proposed system is verified through the experimental results of the laboratory prototype.

Design of optimum self-inductances of magnetic pads in inductive power transfer system for electric vehicles

This paper presents a design process of inducing self-inductances for the lowest power losses of magnetic pads in inductive power transfer (IPT) system. The total losses of the magnetic pads caused by winding coil, ferrite core, and aluminum shield are numerically calculated and achieved by finite element analysis (FEA) simulation. By plotting the total power losses depending on the coil turns of each magnetic pad, the optimum primary and secondary inductances with the minimum power loss are derived. The validity of the design process is verified through the experimental results provided by a 3.3 kW laboratory prototype.

Design and Implementation of an Optimal Hardware for a Stable Operating of Wide Bandgap Devices

In this paper, the GaN FET based phase-shift full-bridge dc-dc converter design is implemented. Switch characteristics of GaN FET were analyzed in detail by comparing state-of-the-art Si MOSFET. Owing to the low conduction resistance and parasitic capacitance, it is expected to GaN FET based power conversion system has improved performance. However, GaN FET is vulnerable to electric interference due to the relatively low threshold voltage and fast switching transient. Therefore, it is necessary to consider PCB layout to design GaN FET based power system because PCB layout is the main reason of stray inductance. To reduce the electric noise, gate voltage of GaN FET is analyzed according to operation mode of phase-shift full-bridge dc-dc converter. Two 600W phase-shifted full-bridge dc-dc converter are designed based on the result to evaluate effects of stray inductance.

Analysis of GaN HEMT-based phase shifted full bridge dc-dc converter

This paper presents the analysis of problem as to when the GaN HEMT (Gallium nitride high electron mobility transistor) is applied to power conversion system. Compared to state-of-the-art super junction Si (Silicon) MOSFET (Metal oxide semiconductor field effect transistor), the FOM (Figure of merit) is much better because of heterojunction structure and wide band gap characteristics. However, designing the power conversion system with GaN HEMT is difficult due to its sensitive threshold voltage. The quite small parasitic capacitance makes it harder to design due to steep dv/dt and di/dt and design factor different from MOSFET as well. In this paper, the printed circuit board layout consideration is analyzed to realize effects of parasitic inductance of power and gate driver loop. In addition, the cause of the ZVS (Zero Voltage Switching) failure is mathematically analyzed as a result of mismatched deadtime. A 600 W phase shifted full bridge dc-dc converter is designed to evaluate effects of parasitic inductance and ZVS failure issues.

Design and analysis of GaN FET-based resonant dc-dc converter

This paper presents a design consideration of GaN FET-based resonant dc-dc converter, and the efficiency and ZVS characteristics of the resonant dc-dc converter based on GaN FET parameters are theoretically analyzed. To verify the validity of analysis, a 600W phase-shift full-bridge dc-dc converter is designed and implemented. The faulty turn-on and ZVS issue caused by GaN FET characteristics are analyzed and their improvement ideas are presented.

Design of output filter in LLC resonant converters for ripple current reduction in battery charging applications

In this paper, a filter design guideline to reduce the ripple current in LLC resonant converters for the battery charger is proposed. The effect of filter inductor on the resonant network is mathematically analyzed, and a filter inductor is designed considering capacitance of the battery. The voltage gain of LLC resonant converter with filter inductor is analyzed through fundamental harmonic approximation (FHA) method. This research verifies performance of ripple current reduction compared with conventional LLC resonant converter without output filter inductor through mathematical analysis, simulation and experimental results.

Design of an portable emergency power supply with multi input sources

This paper presents design guideline of portable emergency power supply with multi input and output requirements. The available structures which satisfy design considerations are proposed and analyzed. Based on the chosen structure, suitable topology and controller of each part applied to charge a battery in a wide range of input condition. In addition, system operation algorithm is proposed according to input and battery voltage condition. The verification of designed prototype for portable emergency power supply is carried out by experiment results in various operation modes.