• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.6
• /
• pp.510-516
• /
• 2007

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor correction (PFC) topology is based on boost topology with boundary conduction mode (BCM). DC/DC topology is based on half-bridge topology with fixed 50% duty and newly introduced off-time control method, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design show that the measured efficiency is 90% with power density of $36W/in^3$. It also shows low no load power consumption of about 0.5W.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.4
• /
• pp.259-265
• /
• 2010

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor corrector (PFC) topology is based on boost topology with boundary conduction mode (BCM) and DC/DC topology is based on LLC resonant converter, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design shows that the measured efficiency is 90% at $90V_{rms}$ input voltage with power density of $36W/in^3$. It also shows low no load power consumption of about 0.5W.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.286-288
• /
• 2007

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor corrector (PFC) topology is based on boost topology with boundary conduction mode (BCM). DC/DC topology is based on half-bridge topology with newly introduced off-time control method, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design shows that the measured efficiency is 90% with power density of $36W/in^3$. It also show low no load power consumption of about 0.5W.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.38-39
• /
• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• Proceedings of the KIPE Conference
• /
• 2003.11a
• /
• pp.85-89
• /
• 2003

Many single-stage PFC(power-facto.-correction) ACHC converters suffer from the high link voltage at high input voltage and light load condition. In this paper, to suppress the link voltage, a novel high power factor high efficiency PFC AC/DC converter is proposed using the single controller which generates two gate signals so that one of them is used far gate signal of the flyback DC/DC converter switch and the other is applied to the Boost PFC stage. A 130w prototype for LCD monitor adapter with universal input $(90-265V_{rms})$ and 19.5V 6.7A output is implemented to verify the operational principles and performances. The experimental results show that the maximum link voltage stress is about 450V at 270Vac input voltage. Moreover, efficiency and power factor are over $84\%$ and 0.95, respectively, under the full load condition.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1418-1423
• /
• 2007

The topology of LLC half bridge resonant converter provides ZVS characteristic. The voltage stress and current stress are smaller than that of the general resonant converters. So the LLC HB resonant converter can be considered as a optimal circuit for the notebook computer adapter. In the adapter design, we should consider the weight, the size and the overheat of the adapter. Thus the higher efficiency is an essential particular. First of all, the optimal design of transformer is the most important facts. Some parameters should be considered in order to get the highest efficiency. The adapter is designed through the considering of these parameters including the PFC circuit as the pre-regulator. It converts AC line input into about DC 390V link voltage of the LLC HB converter input and the converter has 16V/90W ratings. The efficiency measured is about up to 93%.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1039-1040
• /
• 2006

The resonant converters cause the high voltage stress according to the input voltage, which increases the conduction loss in converter power switches. The topology of LLC half bridge resonant converter provides ZVS characteristic and also the stress of voltage and current is not higher than that of the general resonant converters. So we can expect the higher efficiency. In this paper, the LLC resonant converter is designed for the notebook computer adapter. In the adapter design, we should consider the weight, the size and overheat of the adapter. Thus the higher efficiency is an essential particular. First of all, the optimal design of transformer is the most important facts. Some parameters should be considered in order to get the highest efficiency. The adapter is designed through the considering of these parameters including the PFC circuit of the pre-regulator. It converts AC line input into about $400V_{DC}$ Link voltage of the LLC converter input and the converter has $16V_{DC}/90W$ ratings. The efficiency measured is about up to 92%.

• Journal of IKEEE
• /
• v.24 no.3
• /
• pp.828-837
• /
• 2020

This paper presents the optimal design of planar flyback transformer suitable for small-size and low-profile of AC to DC adapter for 10W tablet. This paper also proposes the injection winding transformer of Hybrid and Drum types capable of the winding method of automatic type and the reduction of transformer size and leakage inductance(L_k) compared to the conventional mass-production flyback transformer with the winding method of manual type. In particular, the injection winding transformer of Drum type proposed in this paper is constructed in a horizontal laying of its transformer to solve the connection problem of copper plate injection winding on the secondary side of the one of Hybrid type. The primary and secondary windings of the injection winding transformer of Hybrid and Drum types used the conventional winding and the copper plate injection winding, respectively. For the injection winding transformer of Hybrid and Drum types proposed in this paper, the optimal design of planar flyback transformer suitable for small-size and low-profile was carried out using Maxwell 2D and 3D tool.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.172-174
• /
• 2007

The AC-DC Adapter has been widely used in Mobile Phones, Note Book PC, LCD monitors, and portable electronic products. Recently, high-power-density Adapter was developed. This adapter increases power factor using a bridge diode rectifier and PFC, however, there are weak points that improving efficiency is limited. In the bridgeless rectifier circuit proposed in this paper, there is no PFC, however, the power factor and efficiency are improved by BCM and ZCS operations.

• Proceedings of the KIPE Conference
• /
• 2001.12a
• /
• pp.124-128
• /
• 2001

In this paper, a high-efficiency double-ended active clamp ZVS forward converter is proposed. This converter can be used in compact size AC/DC converter applications such as a notebook adapter. The principles of operation are described and the zero voltage switching characteristics are analyzed. High efficiency of this converter is verified by the experimental results.