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This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type high power dc-dc converter for photovoltaic applications. The proposed step-up DC/DC converters with transformer isolation can obtain high voltage step-up trough turns ratio. The proposed dc-dc power converter is composed of typical voltage source-fed half-bridge high frequency...
In the Tokaido Shinkansen, we built new Electronic Frequency Converter (EFC) to replace Rotary Frequency Changer. The new EFC is individually operated in basic feeding pattern, and there appears the necessity for over-current tolerance in the converters. We describe the application of EFC to the Shinkansen railyard in this paper, showing the development of the control scheme which can control the...
A bi-directional isolated DC/DC converter for medium-voltage applications have been discussed for the next-generation electrical grid, such as smart girds. To realize the DC/DC converter for installing on a power distribution system, it should be achieved higher-efficiency and lower-volume. Higher switching frequency enables to reduce the volume of the transformer. However, it is difficult to realize...
An LDMOS (lateral-diffused MOS) is often used to as the ESD device in a high-voltage circuit for its low on-resistance benefit. But, it has several serious disadvantages, including the Vh value is not high enough and the device in a multi-finger structure can't completely turn on which resulting in the ESD capability per unit length is very low. So, the non-uniform turned-on phenomenon is seriously...
Renewable energy sources such as wind-turbine and photovoltaic power generators may make the power grid unstable due to their output fluctuations. Battery energy storage systems (BESSs) are being considered as a countermeasure for this issue. “BESSs” require bidirectional ac-to-dc and dc-to-ac converters, so improvement of the converter efficiency is desired to improve the efficiency of BESSs. This...
This paper proposes the simple and seamless operation technique for bi-directional LLC resonant converter. Generally, bi-directional operation of LLC resonant converter is complicated and difficult to control. Because, the switching frequency has to be changed across fsr (series resonant frequency) and the switching sequences (the switching timing between high voltage side and low voltage side) has...
An energy storage system is integrated into a power-grid to compensate for the power fluctuation from renewable energy systems. This paper proposes a high-efficiency and low-cost energy storage system for the power-grid. The proposed system combines multi-energy storage devices such as a LaB and an EDLC for reducing the cost incurred by the system for the complete operation period. This paper also...
Large energy-saving effect can be expected for air conditioners that occupy the highest power consumption rate of home appliance, by introducing the SiC. In this paper, the transition of power devices, the characteristics, and the issues in widespread use, and foresight of the next generation power devices, SiC, are reported.
There are applications like railway traction system where power converters for HVAC to MVDC or MDAC to LVDC are required with a high power/weight ratio. The conventional way is to use heavy line frequency or medium frequency transformers followed by a controlled rectifier. The availability of high voltage SiC devices has made it possible to raise the switching frequency to higher value and hence the...
A high performance control strategy for a three-level neutral-point-clamped (NPC) converter employed in electric multiple units traction drive system is proposed in this paper. The strategy is based on a multiple frequency tuned quasi-proportional resonant (PR) controller for the AC current loop. A notch filter is used in the DC bus voltage loop to filter out the ripple affecting the controller. A...
This paper proposes a space vector modulation of a high frequency AC-inked matrix converter which is applied to an electric transformer system. The one of problem of a commercial frequency transformer is bulky and heavy. In order to resolve this problem, we propose to use a high frequency transformer driven by three-phase to single phase matrix converter. In this paper, the virtual indirect control...
Contactless DC connector has been proposed for the next generation 380 V DC distribution system in data centers. A LLC resonant DC-DC converter topology with Gallium Nitride (GaN) power transistors has been applied to realize the short-distance inductively-coupled connector. A prototype of a 1.2 kW 384 V–192 V connector has been fabricated under 500 kHz operation. The conversion efficiency of 95%...
This research presents a power IC technology platform based on AlGaAs/InGaAs/AlGaAs pseudomorphic field effect transistors (pHEMTs) on a GaAs substrate. A quantitative assessment of a foundry-available 11 V GaAs pHEMT process indicates that due to their superior material properties, the intrinsic figure of merit for pHEMT switching devices show an order of magnitude improvement over the state-of-the-art...
Output current of general inverter is controlled based on the information of current sensors which are placed on the output. However, these sensor outputs have gain error and offset which are depending on the peripheral components and the accuracy characteristics of current sensor. Current control performance can be deteriorated a control method which uses a periodic disturbance observer to suppress...
Multiple output converters (MOCs) are widely used for applications which require various levels of the output voltages due to their benefits in cost, volume, and efficiency. However, most of the MOCs developed so far can regulate only one output tightly and require as many secondary windings in the transformer as the number of the outputs. In this paper, a novel Time Division Multiple Control (TDMC)...
This paper describes the characteristics of low frequency ac transmission system using cycloconverters with three configurations. The purpose is to evaluate and choose the most suitable operating frequency and number of phases for this system. The new control scheme is also provided for all operating transmission system. Cable and filter selection are also included in this paper.
In order to save sensors for the grid-connected inverter (GCI) with LCL-filter in the full-scale wind power converter, a grid-side voltage-sensorless solution scheme is presented in this paper. A frequency-adaptive SOGI (FA-SOGI) is introduced to realize the virtual flux (VF) estimation. A grid-side voltage observer is thus designed to acquire the phase angle and amplitude, which can realize voltage...
This paper presents a new high-frequency coupled inductor topology in conjunction with a dielectric isolation device which provides improved efficiency and reduced input currents over conventional magnetic transformers. The main focus of the paper will be the design and operation of this new passive hybrid system, along with a comparison with a regular magnetic high frequency transformer based on...
The multilevel cascaded H-bridge converter is a favorable candidate to directly connect large-scale photovoltaic power plants to the medium voltage electricity network. Nevertheless, due to the lack of a common dc link, the unequal power generation among the three phases, primarily caused by non-uniform solar irradiance, affects its operation. The existing power balancing control methods, however,...
A control strategy for direct-drive PMSG wind generation system based on three phase current source converter (CSC-DPMSG-WGS) is presented in this paper. By the proposed method, once unbalanced grid voltage fault happens, the generator-side converter limits the power which flows to DC-link rapidly, meanwhile the grid-side converter controls the positive and negative sequence currents respectively...
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