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This paper analyzes the conducted noise generation mechanism of totem-pole bridgeless PFC converter in consideration of frame ground capacitor and LISN at every input voltage zero-crossing. The spike current occurs at zero-crossing and causes severe common mode noise. The frequency range on noise spectrum caused by zero-crossing issue is discussed by mathematical calculation. Furthermore, the experimental...
The modular multilevel converter (MMC) is a competitive candidate for VSC-HVDC systems. However, the conventional HB-MMC can't block dc link fault current because of the freewheeling effect of diodes. To solve this problem, researchers proposed an account of sub-modules (SMs) with DC-fault current clearing capability. This paper summarizes the 2 basic criteria and provides a comprehensive review of...
A square wave transmission based micro-grid, which is compatible with commercial AC sinusoidal grid components, is investigated in this paper for rural areas. The basic interface circuit unit, square wave generator (SWG) is designed to satisfy bidirectional power flow and square wave transfer. The square wave has larger power delivery compared to sine wave. The circulating current of paralleled SWGs...
In recent years, direct current power (DC) supply systems have been applied in various types of industrial equipment. As a common practice, an alternating current(AC)/DC converter will be introduced at the system front end to convert mains into DC power sources for system operation. However, when connecting to a power grid, under the influence of load-end characteristics, the phase difference between...
A High Efficiency two-stage AC/DC converter is presented and discussed in this paper, which can be applied in on-board charger for electric vehicles. The front-end converter is a high efficiency ZVS half bridge power factor correction (PFC) topology with only one device in the current flowing path. Owing to the high voltage stress of the half bridge rectifier, the SiC MOSFET is applied to reduce the...
Recent research on high voltage and power DC/DC converter mainly focus on the face-to-face topology based on modular multilevel converters (MMC). The topology consists of two MMC which are coupled by a transformer. It is easy to extend the module number according to the voltage level. However, the present modulation method in this topology cannot regulate the voltage transformation ratio on two dc...
This paper proposed a hybrid power system with combined advantageous features of switching power supply and linear power amplifier. The switching power supply would provide the primary output voltage and power to the load, while the linear power amplifier would act as a correcting amplifying device to compensate for power ripple as a way to stabilize voltage output. Combination of these two components...
This paper proposes a novel hybrid modulation technique for 3-phase dual-stage bidirectional inverter to achieve electrolytic capacitor-less design for the fuel cell vehicles (FCVs) propelling system. The 3-phase bidirectional inverter consists of front-end naturally clamped current-fed dual-active-bridge dc/dc converter and back-end voltage-fed six switches 3-phase inverter. The front-end converter...
This paper topics the effect of the phase-number and the semiconductor-device selection on the volume and weight of a medium-voltage (MV) DC-DC converter intended for offshore wind turbines. In recent years, many papers have discussed the transposition from MVAC to MVDC collector grids in offshore wind, where the main motivation is to reduce losses of the system. The authors have identified that the...
The Cascaded H Bridge (CHB) is a superior topology to integrate PV panels into the grid. However, due to the internal uncertainty power supply of renewable sources, it is difficult to arrange the PV CHB inverter to meet the system scheduling requirement. To overcome this limitation, a CHB inverter topology with both PV arrays and energy storage elements is proposed in this paper. In order to simplify...
In this paper, a novel topology of two-level voltage-type inverter is proposed. The proposed inverter has three bridge arms while each bridge is made up of 2 thyristors, 1 IGBT and 4 diodes. Thyristors complete the phase positioning of the inverter, IGBT completes the modulation of different modulation modes such as SPWM, SVPWM, and SHPWM, and the diodes complete the commutation of the bridge arms...
In this paper, the essential reason of causing the dual-side reactive currents in the isolated dual active bridge (DAB) DC-DC converter is revealed. It is because that the output voltages of the two H-bridge converters of the DAB converter can not keep their polarities the same as the inductor current all the time. The constraint between the two inner phase shifts and the outer phase shift is determined...
A bidirectional integrated bus voltage conditioner (IBVC) is proposed for isolated phase shifted full bridge (PSFB) DC-DC converter to improve the DC bus voltage stability in cascaded power converter system. In this method, the load converter is controlled tightly with high control bandwidth. Unlike those separate converter based DC bus voltage stabilization methods with auxiliary switches, multiplexing...
In this study, a mode transition scheme between a single phase half bridge 2-level voltage source converter (VSC) and a 3-level T-type VSC is proposed. The efficiency of 3-level T-type VSC can be increased by the mode transition scheme. The mode transition scheme select the efficient operation method between a 2-level and 3-level VSC. The 2-level VSC or 3-level VSC operation method are selected depending...
In this paper, three different phase-shift control schemes for a bidirectional series resonant converter are selected for comparative investigation. Based on the fundamental harmonics approximation approach, steady state solutions are obtained for single-phase-shift control, dual-phase-shift control and modified dual-phase-shift control respectively. An extended study is then performed in terms of...
The major drawback of Modular Multilevel Converter (MMC) based variable speed drives is that the capacitor voltage ripple varies inversely with the output frequency. This voltage ripple can be reduced at lower operating frequency by injecting circulating current into its each arm. However, this circulating current increases the overall current rating of the converter. The voltage ripple can also be...
For traditional AC/DC power factor correction (PFC) converters, the diode bridge rectifier is needed in the front-end. While a large current flowing through the bridge, the conduction voltage drop of diodes can result in large power loss. Bridgeless converter can be adopted to improve efficiency and bipolar gain property makes the function of PFC realizable. In this paper, an isolated PFC converter...
In this paper, the main circuit model of EAST (Experimental and Advanced Superconducting Tokamak) fast control power supply is built on RT-LAB semi-physical simulation platform, which forms a feedback closed loop with an external hardware circuit to achieve the function of EAST fast control power supply. The expected effect is achieved in closed-loop simulation experiment, which indicates the feasibility...
In this paper, a duty-cycle control (DCC) method for a three-phase dual-active bridge (DAB3) converter with snubber capacitors is proposed to ensure the zero-voltage switching (ZVS) operation over the whole operation range. Closed-form expressions for the proposed modulation scheme are derived. Furthermore, the equivalent circuit and mathematical model of the converter commutation process are presented...
A new ripple current reduction method utilizing a LLC type ripple current steering circuit is proposed in this paper to significantly reduce 100Hz ripple current in an isolated DC-AC dual active bridge (DAB) converter. Unlike some of the proposed ripple reduction methods for which auxiliary circuit consists of additional switches is applied, this new method benefits from less switching components...
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