Dong-Gyun Woo

A High-Efficient Nonisolated Single-Stage On-Board Battery Charger for Electric Vehicles

The design and implementation of a high-efficiency nonisolated single-stage on-board battery charger (OBC) for electric vehicles are presented. Reviewing the conventional topologies, a suitable circuit structure is determined to charge a battery in a wide spectrum of input and output conditions. Additionally, a suitable strategy for a highly efficient OBC is presented through the analysis of selected topology. A detailed theoretical analysis, operating strategy, and experimental results on a 3.7-kW prototype are presented in order to evaluate the performance of the proposed system.

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.

Comparison of integrated battery chargers for plug-in hybrid electric vehicles: Topology and control

This paper studies battery charging methods utilizing the already available power electronics systems in plug-in hybrid electric vehicles (PHEVs) without an additional charger for charging the battery of PHEVs. Because inverter switch control and motor coils, which are used as the energy storage device for boosting, make the system the boost converter, it is possible to operate the existing system as a battery charger. The main advantages of these charging methods are that space, weight, and cost due to the additional charger are reduced. Various charging methods according to the system topologies and the configurations of the controller are analyzed and verified by PSIM simulation.

Advanced integrated battery chargers for plug-in hybrid electric vehicles

Integrated battery charger (IBC), which uses the already available propulsion system, has a lot of advantages such as low cost and minimum space for the high voltage battery charger. However, it needs to compensate some defects caused by its structure. In this paper, shortcomings of the conventional IBC for PHEVs with interior permanent magnet motors are discussed, and two modified IBCs for better performance are proposed. Performance comparison among three IBCs is carried out; compared with the conventional IBC, two modified IBCs have many strengths like low common noise, simple sensing methods, high efficiency, and so on. Power loss calculation is conducted by the simulation software; then, experimental efficiency evaluation for three IBCs is provided.

Effect of PWM schemes on integrated battery charger for plug-in hybrid electric vehicles: Performance, power factor, and efficiency

Most eco-friendly vehicles can adopt a concept of an integrated battery charger (IBC), which utilizes a motor drive system for charging a high voltage battery pack. The IBCs inevitably require an additional boost inductor when the common mode inductance of the motor/generator (M/G) is too small to satisfy a condition for continuous conduction mode operation. In this paper, the IBC system with the additional boost inductor for plug-in hybrid electric vehicles (PHEVs) is analyzed and system performance according to the pulse-width-modulated (PWM) switching schemes, such as interleaved PWM scheme and synchronous PWM scheme, is discussed in terms of efficiency, power factor, and current distortion factor. Contrary to general multi-phase boost power factor correction converters, the synchronous PWM scheme results in a higher efficiency than the interleaved PWM scheme. The effects of the PWM switching scheme on the IBC system are experimentally demonstrated on a prototype, which consists of a hybrid power control unit for PHEVs and two interior permanent magnet motors.

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.

Analysis and Design of Modified Half-Bridge Series-Resonant Inverter With DC-Link Neutral-Point-Clamped Cell

In this paper, a modified half-bridge (HB) resonant inverter topology with a dc-link neutral-point-clamped cell is proposed. A pseudo asymmetrical voltage-cancellation PWM method and a control strategy are introduced. The proposed topology can maximize the inverter output power factor, and minimize variations in the switching frequency. In addition, most switches are clamped to half of the dc input voltage at turn-off, increasing the overall efficiency of the system for a wide load range. The efficiency of the proposed inverter is improved up to 7% at light-load conditions compared with that of the conventional HB inverter. Informative expressions for performance comparison between the proposed inverter and its counterpart are provided. In addition, the losses in the inverter primary components are analytically analyzed in detail. For validation, a 120-W prototype is implemented, and experimental results are presented.

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.

Loss Analysis of Power Conversion Equipment for Efficiency Improvement

This paper suggests loss analysis and calculation methods for efficiency improvement of power conversion equipment in detail. The detailed loss analysis and calculation has been conducted for 3.3kW On-board Battery Charger considering temperature condition. The validity of the analysis and calculation method is verified by simulation model.

Compensation Scheme for Output Voltage Distortion in Fuel Cell Stack with Internal Humidifier

In this paper, the characteristics of portable fuel cell system are introduced and the dynamic response of output voltage of fuel cell stack with internal humidifier is analyzed. When the output of the fuel cell (FC) stack is short-circuited for humidification, the output voltage of the FC stack rapidly drops. In order to maintain the load voltage in the required range, dynamic compensation methods are proposed: 1) installing a capacitor behind the output of the FC stack; 2) utilizing the bi-directional converter. Especially, bi-directional converter is used when short of the FC output is detected or predicted by algorithm using data which is measured during previous three cycles. These methods are simulated by PSIM 9.0, then experimental results from the fuel cell system prototype verify the validity of the proposed methods.