Yu-Chen Chang

A module-integrated isolated solar micro-inverter

This paper presents a module-integrated isolated solar micro-inverter with pseudo-DC link. The studied grid-tied micro-inverters can individually extract the maximum solar power from each photovoltaic (PV) panel and transfer to the AC utility system. High conversion efficiency and high maximum power point tracking (MPPT) accuracy can be achieved with the studied pseudo-DC link topology. The operation principles and design considerations of the studied solar inverter are analyzed and discussed. A laboratory prototype is implemented and tested to verify its feasibility.

Efficiency improvement in adjustable deadtime of LLC resonant converters

This paper presents an analysis of high efficiency feasibility at wide load in LLC-SRC Resonant Converter. LLC-SRC Resonant Converter could be achieved zero voltage switching turn on by resonant scheme. A fixed deadtime must be larger than the discharge time for the effective drain-source capacitance of Mosfet during switching off. Ensure that parasitic capacitance of the half bridge including Mosfets capacitance has been discharged before switching turn on. But conduction loss is appeared Transformer and Power Mosfet at heavy load. Because resonant current is higher than enough to obtain discharge capability by proper magnetic inductance. Especially, the resonant tank current flows through into the body diode of Mosfet at heavy load. In order to achieve high efficiency of LLC-SRC resonant converters. An adjustable deadtime could be feasibly to improve efficiency from light load to heavy load.

Design and implementation of a high-efficiency LiFePO4 battery charger for electric vehicle applications

This letter studies and implements a high-efficiency LiFePO4 battery charger. The modular design can satisfy the requirements of series/parallel charging for electric vehicle applications. A CC-CC-CV charging scheme is also realized to meet the characteristics of LiFePO4 battery stacks. A 2 kW laboratory prototype is built and tested. The experimental results are shown to verify the feasibility of the proposed scheme. Copyright

High‐voltage power amplifier for flexible paper speaker applications

This paper presents a high-voltage power amplifier for driving flexible paper speaker. Simple circuit complexity and high signal quality can be achieved. The operating principles and design considerations of the studied paper speaker power amplifier are analyzed and discussed. A laboratory prototype is built and tested. The experimental results are shown to verify the studied scheme.

Design and implementation of a contact-less power charger for robot applications

In this paper, a contact-less power charger for robot applications is studied and developed. Non-contact charging can be achieved by a separable magnetic-transformer design. The transformer primary core is in the charger unit and the secondary core is in the robots. The transformer air-gap is equal to the distance between these two parts. By theoretical analysis, software simulations and circuit implementation, the relationships between the transformers coupling coefficient and the core geometry and gap are formulated. In addition, a high-efficiency circuit topology for the studied contact-less charger is fulfilled. It is anticipated that the research results of this paper can contribute to the development of the contact-less charging techniques for robot systems.

A module-integrated isolated solar micro-inverter without electrolytic capacitors

This paper presents a module-integrated isolated solar micro-inverter. The studied grid-tied micro-inverters can individually extract the maximum solar power from each photovoltaic (PV) panel and transfer to the AC utility system. A harmonic suppression technique is used to reduce the DC-bus capacitance. Electrolytic capacitors are not needed in the studied solar micro-inverter. High conversion efficiency, high MPPT accuracy and long lifespan can be achieved. The operation principles and design considerations of the studied PV inverter are analyzed and discussed. A laboratory prototype is implemented and tested to verify its feasibility.

Design and implementation of high efficiency low-profile bidirectional dc-dc converter

Bidirectional dc-dc converter is an important part of battery energy storage to efficiently control the power flow in or out of the battery. Due to the limited stored energy, it is very important to maximize the amount of deliverable energy to the load by minimizing the losses in the power conversion. In this paper, the proposed high efficiency bidirectional DC-DC converter is based on series resonant converter (SRC) topology. The circuit is realized by using full bridge on primary and secondary side. Silicon carbide (SiC) MOSFET is utilized on the primary side to significantly reduce the losses on the primary side switches. A 1.5 kW 750V/ 15V prototype converter was implemented and tested to verify the design. From the experimental results, a 96.22% of peak efficiency for both buck and boost modes was achieved.

Output double-line frequency ripple reduction method for high power density interleaved boost converters in power factor correction applications

A three-phase interleaved boost converter stage of an ac-dc PFC converter that uses GaN switches is developed that utilizes a feed-forward band-stop filter control method to suppress low-frequency output voltage ripple. To increase power density, the converter switches at 500 kHz, operates in triangular current mode (TCM) to achieve zero voltage switching (ZVS), and uses GaN switching devices. A 1-kW laboratory prototype was designed and tested to verify feasibility. With the proposed controller, output ripple was reduced by 70%. Overall efficiency is greater than 96.5% and power density is 65.028 W/in3.

Circuit design and performance evaluation of high-voltage power amplifier for flexible paper speaker applications

This paper presents a high-voltage power amplifier for driving flexible paper speaker. Simple circuit complexity and high signal quality can be achieved. The operating principles and design considerations of the studied paper speaker power amplifier are analyzed and discussed. A laboratory prototype is built and tested. The experimental results are shown to verify the studied scheme.

Design and implementation of a high-voltage power supply for industrial In-mold labeling applications

This paper designs and implements a high-voltage DC power supply with wide-range output voltage up to 30kV. There are two stages for the power conversion. The pre-stage circuit is a transition-mode (TM) power factor correction (PFC) converter for improving input power factor and providing a regulated 380V DC output. The post-stage is a DC/DC converter, to use a buck-type current-fed push-pull as its configuration; the secondary is a multiple-voltage circuit, for producing 5-30kV high voltage output. A control interface is also designed to communicate with remote control unit via controller area network (CAN) bus communication protocols. Operating principles and design considerations of the studied high-voltage power supply are discussed and analyzed. Finally, a 150W laboratory prototype was implemented and tested to verify the feasibility of the proposed scheme.