• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 전력전자학술대회 논문집
• /
• pp.399-400
• /
• 2012

The proposed battery charger presented in this paper is suitable for Lead-Acid Battery and the dc/dc buck converter topology is applied as a charger circuit. The technique adopted in this charger is constant current & constant voltage dual mode, which is decided by the value of voltage of proposed battery. Automatic mode change function is detected by the percentage value of level of battery charging. CC Mode (Constant Current Mode) is operated when charging level is below 80% of the total charging of Battery voltage and above 80% of battery voltage charging, CV Mode (Constant Voltage Mode) is automatically operated. As the charging level exceeds 120%, it automatically terminates charging. The feedback signal to the PWM generator for charging the battery is controlled by using the current and voltage measurement circuits simultaneously. This technique will degrade the damage of proposed type of battery and improve the power efficiency of charger. Finally, a prototype charger circuit designed for a 12-V 7-Ah lead acid battery is constructed and tested to confirm the theoretical predictions. Satisfactory performance is obtained from simulation and the experimental results.

• Journal of Electrical Engineering and Technology
• /
• 제11권1호
• /
• pp.143-149
• /
• 2016

The two-stage converter is widely used in traditional DC/AC inverter. It has several disadvantages such as complex topology, large volume and high loss. In order to overcome these shortcomings, a novel half load-cycle worked dual SEPIC single-stage inverter, which is based on the analysis of the relationship between input and output voltages of SEPIC converters operating in the discontinuous conduction mode (DCM), is presented in this paper. The traditional single-stage inverter has remarkable advantages in small and medium power applications, but it can’t realize boost DC/AC output directly. Besides one pre-boost DC/DC converter is needed between the DC source and the traditional single-stage inverter. A novel DC/AC inverter without pre-boost DC/DC converter, which is comprised of two SEPIC converters, is studied. The output of dual SEPIC converters is connected with anti-parallel and half load-cycle control is used to realize boost and buck DC/AC output directly and work properly, whatever the DC input voltage is higher or lower than the AC output voltage. The working principle, parameter selection and the control strategy of the inverters are analyzed in this paper. Simulation and experiment results verify the feasibility of the new inverter.

• 한국산학기술학회논문지
• /
• 제17권9호
• /
• pp.21-26
• /
• 2016

본 논문에서는 휴대 전자기기의 내부 전원단을 위한, CCM/DCM 기능의 이중모드 감압형 DC-DC 벅 컨버터를 제안한다. 제안하는 변환기는 1 MHz의 주파수에서 동작하며, 파워단과 제어블럭으로 이루어진다. 파워단은 Power MOS 트랜지스터, 인덕터, 커패시터, 제어 루프용 피드백 저항으로 구성된다. 제어부는 펄스폭 변조기 (PWM), 오차증폭기, 램프 파 발생기, 오실레이터 등으로 이루진다. 또한 본 논문에서 보상단의 큰 외부 커패시터는, 집적회로의 면적축소를 위하여 CMOS 회로로 구성되는 멀티플라이어 등가 커패시터로 대체하였다. 또한,. 본 논문에서, 보상단의 외부 커패시터는 집적회로의 면적을 줄이기 위하여 곱셈기 기반 CMOS 등가회로로 대체하였다. 또한 제안하는 회로는 칩을 보호하기 위하여 출력 과전압, 입력부족 차단 보호회로 및 과열 차단 보호회로를 내장하였다. 제안하는 회로는 $0.18{\mu}m$ CMOS 공정을 사용하여, 케이던스의 스펙트라 회로설계 프로그램을 이용하여 설계 및 검증을 하였다. SPICE 모의 실험 결과, 설계된 이중모드 DC-DC 벅 변환기는 94.8 %의 피크효율, 3.29 mV의 리플전압, 2.7 ~ 3.3 V의 전압 조건에서 1.8 V의 출력전압을 보였다.

• Journal of Electrical Engineering and Technology
• /
• 제13권1호
• /
• pp.226-239
• /
• 2018

In this paper, design and control method ZVT Interleaved Bidirectional LDC(IB-LDC) for mild-hybrid electric vehicle is proposed. The IB-LDC is composed of interleaved buck and boost converters employing an auxiliary inductor and auxiliary capacitors to achieve zero-voltage-transition. Operating principle of IB-LDC according to operation mode is introduced and mathematically analyzed in buck and boost mode. Moreover, PFM and phase control are proposed to reduce circulating current for low power range. Passive components design such as main inductor, auxiliary inductor and capacitors is suggested, considering ZVT condition and maximizing efficiency. Furthermore, a 600W prototype of ZVT IB-LDC for MHEVs is built and tested to verify validity.

• 한국자동차공학회논문집
• /
• 제25권1호
• /
• pp.82-91
• /
• 2017

This paper is a study on the bi-directional DC-DC converter, one of the key elements of 48V-12V dual systems in mild hybrid electric vehicles. Mild hybrid electric vehicles require a bi-directional DC-DC converter that can efficiently transmit power in two directions between a 48V battery and a 12V battery. To develop a bi-directional DC-DC converter with better price competitiveness, upgraded fuel economy, excellent performance and smaller size, this study designed, produced and presented a circuit that improved on the existing one. In the proposed 8-phase bi-directional DC-DC converter, the size of the passive element was reduced through the 8-phase interleaved topology, whereas downscaling had previously posed a difficulty. This study also designed and produced a 2.5kW class prototype. Based on the proposed 8-phase interleaved topology, a size of 227.5 (W) * 172 (L) * 64.35 (H) was achieved. In the boost mode operation and buck operation modes, the maximum efficiency was recorded at 94.04 % and 95.78 %, respectively.