Main Circuit Topology Research Articles

Design of a 260 kVA auxiliary converter based on passive soft-switching

In this paper, a 260 kVA auxiliary converter equipped with passive soft-switching is designed by using modular design method and DC-(AC)-DC-AC converting technique. Firstly, main circuit topology of designed auxiliary converter consisting of a DC/DC module and a DC/AC module is given, and a new type connection mode of DC/DC module is described. Then, the principle and characteristics of buffered passive soft-switching is analysed in detail, and key circuits of the auxiliary converter are also designed. Finally, some experiments are carried out based on a built experimental setup, and the results show the effectiveness and validity of the proposed auxiliary converter.

Experimental Study on Improved Phase-Shift Control Soft-Switching Converter

A novel phase-shifted Soft-switching converter is presented in this thesis，which is based on the Tou structural, groundwork of summarization of the development of lower Electronics in recent years and lucubration in theoretical basis of modern high frequency soft switching power convert technique and analysis of operation principle, characteristic of the circuit and inherent drawbacks of traditional phase-shifted Soft-switching converter. Explicit description of main circuit topology, operation principle, characteristic of the circuit of the novel phase-shifted Soft-switching converter as well as the simulation analysis with the PSPICE software is proposed. The main works that I did: The design involves calculation of transformer, inductor and capacitance in main circuit, parameter selection of each element and realization of control circuit. Electric circuit Tou structural is verified by emulation experiment. The electric circuit reduces availably switch exhaust of traditional soft switch transformation electric circuit. The experiment proved to the possibility of the reformed prefect. The experiment has important reference value to improved soft switch transformation.

Study on Steady- and Transient-State Characteristics of a New HVDC Transmission System Based on an Inductive Filtering Method

Different from the main circuit topology of the traditional current source converter (CSC)-based HVdc transmission system, this paper proposes a new CSC-HVdc transmission system based on a new inductive filtering method. Such new HVdc system characters as a new main circuit topology and mainly contains a new converter transformer and related full-tuned (FT) branches. With regard to the implementation conditions of the new inductive filtering method, the basic main circuit parameter design for the new converter transformer, the related FT branches, and the HVdc control system are presented, respectively. Based on these designed main circuit parameters and control system, the new CSC-HVdc system is modeled in the PSCAD/EMTDC environment, and correspondingly, through comparative study with the International Council on Large Electric Systems (CIGRE) HVdc benchmark model, the steady- and the transient-state operating characteristics of the new CSC-HVdc system are studied in detail. The research results show that the new CSC-HVdc system can widen the stable operating range, increase the dc transmission capacity, and meanwhile, improve the commutating performance of the CSC-HVdc converter. Moreover, it maintains the stable operating performance and represents the good fault-recovery ability when suffering the typical faults (e.g., single-phase or three-phase faults at the rectifier and the inverter side of the HVdc transmission system).

Research on the DSP- Based Grid-Connect Inverter for 3kW Fuel Cells

In this paper, the single-phase synchronization inverter of fuel cell is taken as the main topic. The network system topology, the control strategy and the phase-locked algorithm are analyzed in detail. The system’s main circuit topology, the software PLL principles and process are proposed, and they are verified by the experiments.

Study on the Electric Vehicle Wireless Power Supply Technology and System Based on ICPT

The electric vehicle power supply technology based on wireless power transfer (EVPS-WPT) has several advantages over conventional energy transmission using wires and connectors, such as flexibility, convenience, safety, reliability and all-weather operation, etc. The development of EVPS-WPT will certainly promote the popularization and industrialization of EVs. The fundamental structure of electric vehicle wireless power supply system based on ICPT (EVPS-ICPT) is described firstly in this paper. A supposed dynamic battery charging system for electric vehicles based on ICPT (EVC-ICPT-D) is proposed to explain some concepts more clearly. The main circuit topology of EVPS-ICPT system is also discussed and selected. As the focus of this paper, the key techniques for EVPS-ICPT system are discussed and analyzed in the round.

A Stages Compensation and Control Strategy for Series Power-Quality Regulator

A novel stages compensation and control strategy suitable for a series power-quality regulator (SPQR) based on a voltage-source converter (VSC) inverter is proposed in which steady operation stage, overrun operation stage, and recovery operation stage are included. The presag voltage compensation, minimum energy compensation, and maximum energy compensation strategies are adopted to the three stages, respectively, based on the characteristics of the three stages. The double closed-loop control with feedbacks from load voltage and filter capacitor current is used in each stage. Moreover, the dc capacitor voltage regulation control for SPQR is applied in the steady operation stage. To avoid switching disorder during the stage change, a criterion based on voltage magnitude of the dc capacitor and source side is proposed. Simulation results in EMTDC/PSCAD show that voltage disturbances of the steady and transient state can be compensated by using the proposed compensation and control strategy and, at the same time, the dc capacitor voltage can be stabilized. The proposed strategy makes it possible to use the dc capacitor as the energy source of SPQR with the merit of a simple main circuit topology.

A Methodology to Teach Advanced A/D Converters, Combining Digital Signal Processing and Microelectronics Perspectives

ADCs (analog-to-digital converters), especially Pipeline and Sigma-Delta (Σ-Δ) converters, are designed using complex architectures in order to increase their sampling rate and/or resolution. Consequently, the learning of ADC devices also encompasses complex concepts such as multistage synchronization, latency, oversampling, modulation, noise shaping, filtering, or decimation. This paper is focused on a new learning methodology, based on the simulation of the main circuit topologies used in commercial ADCs, in order to understand their working principles more thoroughly. At the same time, the ADC dynamic and static tests are obtained from the simulation results, and their characterization is obtained at an application level. In this way, the methodology combines the microelectronics perspective, at the design level, with the digital signal processing perspective. This methodology saves time in practical classes and encourages self-learning because it does not require special hardware. Moreover, it uses only software tools that are common in electronic engineering, like the OrCAD PSpice simulator, a C compiler, or a hardware description language (HDL) simulator. The methodology has been validated during two consecutive offerings of academic courses in the Telecommunication Engineering curriculum at Vigo University, Vigo, Spain, and the results obtained are discussed.

Design of 2000kW switched reluctance machine system

The switched reluctance machine system with high reliability and fault tolerance capability has good perspective for large power applications. The machine, the topology of the power converter main circuit and the control strategy should be taken into account as a whole for the design of the switched reluctance machine system. Four-phase 8/6 pole switched reluctance machine and four-phase asymmetric bridge power converter should be adopted in large power system with consideration of the fault tolerance capability and low voltage & current rating of power switches in power converter. The primary election of the structure parameters for 2000kW switched reluctance machine can be calculated based on the output equation and the equation of the turn numbers of phase winding. The nonlinear simulation of the system was made by taking as a whole the magnetization curves of the machine obtained by using two dimensional finite element electromagnetic field calculation, the topology of the power converter main circuit and the control strategy. The electromagnetic parameters and the structural parameters of the machine, the control parameters of the system were modified continuously until the output power and efficiency were satisfied. The magnetic flux paths of the prototype were given. The hardware-in-the-loop simulation on the controller and the system was finished based on RT-LAB simulator.

Transformer-Less Series Voltage Sag Compensator without Energy Storage Capacitor for Three-Phase Three-Line Systems

A novel main circuit topology of transformer-less series voltage sag compensator is proposed. The sagged voltages are compensated by half bridge inverters, which are directly connected in series with the residual voltages and are charged by the residual line-to-line voltages. The proposed compensator can compensate symmetrical three-phase sags down to 37%, or one or two phase sags down to zero if at least one phase is rated voltage. Besides the excellent compensation property related to the compensating depth, the proposed system only need small capacitance in the inverters because they are continuously charged by the residual voltages during the sags. In fact the capacitors are not energy storers but filters, so there is no limit on their compensating time interval. Theoretical analysis is done and the concerned results are derived. Simulation results on resistance loads demonstrated the compensating performances.

QUICK CHARGE SYSTEM OF LEAD-ACID BATTERY FOR ELECTRIC VEHICLES

In order to improve the charging efficiency of lead-acid battery, shorten the charging time , a quick charger of the lead-acid battery for electric vehicles is designed to multi- stage current-adjusting mode on the basis of fast pulse charge theory and dynamic circuit model. Main circuit topology of phase full-bridge soft switch is applied to the charger. It has high efficiency, low voltage and amplifier stress and good reliability. Experimental results show pluse charge technology has shorter charging time, higher charging efficiency and lower temperature increasing during the charging process, comparing with constant current-constant voltage charging mode. As a result, pluse charge for lead-acid battery make the battery polarization reduce efficiently. Theory and experiment verify the method of fast pulse charge.

A 0.3 MJ SMES Magnet of a Voltage Sag Compensation System

To protect an 110 kVA critical load from voltage sags, a SMES-based voltage sag compensator is developed. This system consists of a 0.3 MJ NbTi magnet and a 150 kVA IGBT-based current source converter. The magnet has a solenoidal coil with an inductance of 1.85 H. Its helium-vapor cooled HTS current leads are further cooled by liquid nitrogen. A protection system is designed for quenches which would most likely happen during the period of charging or discharging of the magnet when a voltage sag occurs or the voltage supply recovers from a sag. The topology of the main circuit of the compensator is also presented and analyzed.

Analytical calculation of air-gap magnetic field distribution and instantaneous characteristics of brushless dc motors

This paper derives the relative air-gap-specific permeance distribution function by Schwarz-Christoffel transformation, considering the effect of slotting. Neglecting the iron saturation, and employing the analytical algorithm for partial differential equations, efficient and effective analytical calculations of no-load air-gap magnetic field distribution, armature field distribution, and phase electromotive force (EMF), are demonstrated, considering the stator slots. Subsequently, based on the main circuit topology of a brushless DC motor (BLDCM), the field-circuit coupling model is constructed for the motor, and then the phase current waveforms and load air-gap magnetic field distribution at any time are determined. Consequently, the instantaneous electromagnetic torque is computed, which underpins the quantitative analysis of torque ripple and the pulsation induced by commutation. Hence, the present work paves the way to precise prediction of the motor's performance and acoustic noise. It is a powerful tool for the design of surface permanent magnet brushless DC motors.