• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.3
• /
• pp.181-190
• /
• 2019

Active power decoupling circuits have emerged to eliminate the inherent second-order ripple power in a single-phase power conversion system. This study proposes a design method to determine the optimal capacitance for active power decoupling circuits to achieve high power density. Minimum capacitance is derived by analyzing ripple power in a passive power decoupling circuit, a buck-type circuit, and a capacitor-split-type circuit. Double-frequency ripple power decoupling capabilities are also analyzed in three decoupling circuits under a 3.3 kW load condition for a battery charger application. To verify the proposed design method, the performance of the three decoupling circuits with the derived minimum capacitance is compared and analyzed through the results of MATLAB -Simulink and hardware-in-the-loop simulations.

• Journal of Power Electronics
• /
• v.13 no.4
• /
• pp.558-568
• /
• 2013

In this paper, a new decoupling technique for a flyback inverter using an active power decoupling circuit with auxiliary winding and a novel switching pattern is proposed. The conventional passive power decoupling method is applied to control Maximum Power Point Tracking (MPPT) efficiently by attenuating double frequency power pulsation on the photovoltaic (PV) side. In this case, decoupling capacitor for a flyback inverter is essentially required large electrolytic capacitor of milli-farads. However using the electrolytic capacitor have problems of bulky size and short life-span. Because this electrolytic capacitor is strongly concerned with the life-span of an AC module system, an active power decoupling circuit to minimize input capacitance is needed. In the proposed topology, auxiliary winding defined as a Ripple port will partially cover difference between a PV power and an AC Power. Since input capacitor and auxiliary capacitor is reduced by Ripple port, it can be replaced by a film capacitor. To perform the operation of charging/discharging decoupling capacitor $C_x$, a novel switching sequence is also proposed. The proposed topology is verified by design analysis, simulation and experimental results.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.486-487
• /
• 2012

In this paper, novel three-port active power decoupling (APD) method for applying 250[W] micro-inverter. This type using third port for active power decoupling stores the surplus energy and supplies sufficient energy to grid. Conventional decoupling circuit is applied in single phase grid connected micro-inverter especially single-stage configuration like flyback-type DC-AC inverter. In this passive power decoupling method, electrolytic capacitor with large capacitance is needed for decoupling from constant DC power and instantaneous AC power. However the decoupling capacitor is replaced with film capacitor by using APD, thus the overall system can achieve smaller size and long lifespan. Proposed three-port flyback inverter is verified by design and simulation.

• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.137-138
• /
• 2012

In this paper, three-port flyback inverter with Active Power Decoupling(APD) circuit is analyzed. Conventional flyback inverter with passive power decoupling circuit needs the electrolytic capacitor with large capacitance for decoupling between constant DC power and instantaneous AC power. However the electrolytic capacitor has low lifespan about 50000 to 100000 hours. So the active power decoupling techniques are applied to reduce input capacitance of flyback inverter. Thus the overall system can achieve smaller size and longer lifespan. Proposed three-port flyback inverter is verified by design optimization, simulation and experimental result.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.2
• /
• pp.157-164
• /
• 2022

This study proposes an enhanced quadruple-Active-Bridge (QAB) converter that can solve power coupling problems. By adopting a multiple winding transformer, the equivalent circuit of a conventional QAB converter has power couplings between arbitrary output ports. This coupling is an unintended power relationship that complicates the regulation of output voltage of the multiple ports. The proposed converter can carry out power decoupling by changing the arrangement of the coupling inductor. Power transfer equations for the proposed converter and its operating principles are analyzed in detail. The power coupling caused by the transformer's leakage inductance is verified by using a proposed coupling factor that presents the relationship between inductance ratio and coupling power. In addition, the decoupling power control performance of the proposed converter is verified by simulation and a 3 kW prototype converter.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.23 no.2
• /
• pp.121-128
• /
• 2018

This work proposes a simple control method of a buck-type active power decoupling circuit that can minimize the ripple values in the dc link voltage. The proposed method utilizes a simplified duty calculation method and an optimal compensation gain tracking algorithm with variable-step approach. Thus, the dc link voltage ripple can be effectively reduced through the proposed method along with rapid response in tracking the optimum compensation gain. Moreover, the proposed method has better dynamic responses in the load fluctuation or abnormal situation. MATLAB/Simulink simulation and hardware-in-the-loop-simulation(HILS)-based experimental results are presented to validate the effectiveness of the proposed control method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.23 no.6
• /
• pp.389-396
• /
• 2018

This study proposes a control method using a repetitive controller for a boost-type PFC rectifier with an APD circuit structure to improve the current distortion caused by DCM condition. Conventional proportional integral controllers have bandwidth limitations in DCM conditions. The performance improvement of the APD controller in the DCM region is verified through simulations and experiments on the compensation of harmonics by the repetitive controller.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.246-247
• /
• 2017

단상 ac/dc, dc/ac 시스템의 경우, ac와 dc사이의 전력 불균형으로 인해 double line frequency ripple power가 발생한다. 이는 harmonic disturbance을 야기시킨다. 일반적으로 전력 리플을 줄이기 위하여 dc-link에 용량이 큰 전해 커패시터를 사용하는데, 용량이 큰 전해 커패시터는 높은 equivalent series resistance(ESR)을 가지며, 상대적으로 짧은 수명을 갖는 한계를 갖는다. 본 논문은 active power decoupling을 추가함으로써 전해 커패시터를 용량이 작은 필름 커패시터로 대체한 회로 구조를 제시한다. 그리고 dc-link 커패시터 선정방법, 설계한 제어기의 성능과 부하 변동에 따른 실험을 PSIM 시뮬레이션으로 확인하고 실험을 통해 검증한다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.4
• /
• pp.294-297
• /
• 2021

A grid voltage estimation method for modular plug-in active power decoupling (APD) circuits is proposed in this study as direct replacements of electrolytic capacitors. Since modular plug-in APD circuits cannot have additional grid voltage sensors and should be operated independently without information exchange with the front-end converter, it is impossible to obtain the phase information of the grid directly. Therefore, the proposed method uses the second-order harmonic component of the DC-link voltage to estimate the grid voltage necessary to control the APD circuit. By employing the proposed method, the concept of modular plug-in APD circuits can be realized and implemented without direct detection of the grid voltage. The experimental results based on hardware-in-the-loop simulation (HILS) validate the effectiveness of the proposed control method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.4
• /
• pp.286-292
• /
• 2020

This study proposes a power decoupled multi-port dual-active-bridge (DAB) DC-DC converter employing multiple transformers. Conventional multiport DAB DC-DC converters experience a power coupling issue from the use of a single transformer, which essentially requires complex power decoupling control. To solve this issue, a multiport DAB DC-DC converter employing multiple transformers is proposed to decouple output power without additional complex control algorithms. The proposed converter uses multiple transformers that can expand output ports easily. Therefore, transformers and the proposed multi-port DAB converter can be designed simply. In addition, the number of coupling inductors can be reduced in the proposed three-port DAB converter compared with that in conventional multiport DAB converters. The power decoupling characteristics and equivalent circuit of the proposed converter are analyzed using theoretical model approaches. Finally, a 3-kW laboratory prototype is developed to verify the effectiveness of the proposed converter.