Weiyang Wu

Research on Control Method of Double-Mode Inverter with Grid-Connection and Stand-Alone

Inverter system, as the interface device between the renewable energy system and grid, plays an important role in the distributed generation system. A double-mode single-phase inverter system, which can be operated in grid-connected mode or stand-alone mode with seamless transitions control, is proposed in this paper. The different control strategies applied on the system for the different modes are designed. In the grid-connected mode, the grid governs the load voltage, the inverter operates as a current source, and the grid current is directly controlled by a three-level hysteresis controller for faster dynamic responsibility and lower current ripple. In the stand-alone mode, the inverter is voltage-controlled, fuzzy controller with parameter self-adapting on-line is introduced to improve the system adaptability to the varieties of load and system parameters, so good quality of output sine-voltage can be obtained under various load conditions. In order to make the distributed generation utility-interactive, an algorithm, which controls the inverter to transfer seamlessly between grid-connected mode and stand-alone mode, is present. The DSP (TMS320LF2407A) based inverter prototype is developed to verify the analysis

A Rogowski coil current transducer designed for wide bandwidth current pulse measurement

In this paper, high frequency behavior for a Rogowski coil is analyzed. Considering the coil frequency response model, a design method for this transducer is presented that the damping ratio based on termination resistor divides the coil frequency band into three bands: derivation band, proportion band and resonance band. Corresponding outside integrator circuits are built according with every band characteristic. A novel compound integration circuit is described in this paper which is consisted of self-integration, passive RC integration and active RC integration. This compound integrator improvements the measurement upper bandwidth limit of transducer above coil natural frequency. A coil of 100 wound number is constructed using compound integrator which is designed under 50Hz∼2.8MHz and sensitivity of 1mV/A. Simulation and experiment waveforms verify the transducer operates with both 50Hz grid current and 750A/us di/dt pulse current measurement.

FPGA Based Multichannel PWM Pulse Generator for Multi-modular Converters or Multilevel Converters

Familiar special microprocessor with PWM pulse generator cannot provide enough PWM pulses for multi-modular converters or multilevel converters. Field programmable gate array (FPGA) is applied to implement the multichannel PWM pulse generator with no synchronization and communication trouble due to the single chip structure of FPGA compared with the multi-microprocessor scheme. A three-phase voltage source 5-level cascade inverter prototype with sample time staggered space vector modulation is accomplished to verify the correctness of the proposed multichannel PWM pulse generator

Adaptive Three Dimensional Space Vector Modulation in abc Coordinates for Three Phase Four Wire Split Capacitor Converter

A new three dimensional space vector modulation (3D-SVM) strategy in abc coordinates for the three phase four wire converter with split-capacitor is presented. Among various three phase four wire converters, the center split converter is suit to low cost, low power applications for its fewer switches. Compare to the 3D-SVM in alphabetagammacoordinates, the strategy in abc coordinates is more clearly and simpler, and therefore the complexity of modulation algorithm and the computational burden are dramatically reduced. An adaptive 3D SVM is employed to compensate the voltage variation of split capacitors. A 3 kVA prototype is established and the experimental results are presented to validate the method

A Novel Bidirectional Three Phase Boost DC/DC Converter as Front-End Stage for High Power Applications

A Novel bidirectional three phase Boost DC/DC converter is proposed in this paper. The circuit topology is similar to a traditional three phase AC PWM rectifier, but the inputs are alternated by DC power sources, such as DC bus or batteries. The purposed converter can be used as front-end stage for high power applications. Also, it can be applied for dual input-voltage power supplies, such as a wind/photovoltaic energy hybrid system, where DC bus and AC bus are coexisted. Because the topology of the converter is derived from three phase AC devices, it has a natural capability to deal with this problem well. Simplified Three-Dimensional Space Vector Modulation (3D-SVM) strategy is employed to deal with unbalanced three phase sources or unbalanced three phase sources. The analysis has been verified by experimental results.

Shunt Active Power Filter with Sample Time Staggered Space Vector Modulation Based Cascade Multilevel Converters

Sample time staggered space vector modulation (STS-SVM) is a kind of new modulation strategy for large-capacity power electronic equipments, which is of excellent harmonic characteristic, wide transmitting bandwidth, average switching load and easy digital algorithm. With STS-SVM, cascade multilevel converters can achieve a high equivalent switching frequency effect at very low real device switching frequency, which is much suitable for large capacity APF. A shunt active power filter experimental prototype with STS-SVM based cascade multilevel converters is established. Experimental results verify that this APF can compensate the harmonic and reactive current correctly and validly

Compact high voltage solid-state pulse generator based on series RSD

The series Reverse Switched-on Dynistor (RSD) assembly drive technology based on integrating RSD switch and its triggering circuit was considered in this paper for the construction of a compact high voltage solid-state pulsed power generator which operated in a rep-frequency discharge mode. Firstly, RSD semiconductor reverse-triggering model was presented based on the elements quasi-diode mode. An additional RSD serial resonance triggering circuit was set up. Based on this platform, direct-triggering experiments contributed to get the data used in the proposed model. Secondly, MATLAB simulation based on the Integration unit resonant triggering circuit and this RSD model was conducted. And the resonant parameters of 0.5Ω 1.75μH and 0.2μF are derived under the requirement of RSD conduct current in main circuit, which set demands to charge of triggering carries injected in the pnn+ diode necessary for uniform RSD stitching. Furthermore, the additional product value of the voltage by the delay time caused by limited trigger resonant frequency must be taken into account during magnetic parameters design for saturated choke. Moderate Vt product on the core ensures the RSD triggering process completed in an accurate range of 2μs. At last, RSD triggering experimental results verify the reverse triggering model and resonant parameters. It is possible to implement a 10kV high voltage pulsed power generator utilizing series RSD unit.

Waveform Library Control of Converter

A novel control method which named waveform library control is presented in this paper. This control method is based on the rated open loop waveforms instead of mathematical model as usual. The proposed control method is easy to be realized because it only needs to collect the typical system response waveform without the mathematical model. As an exploration for power electronic circuit waveform control, the research is important to improve the control performance and decrease the design cost. In the paper, we present two control schemes of the method, and the feasibility of the method is verified by the simulation and experiment results

A novel indirect current controlled realization for the three phase voltage source reversible converter

In this paper, the output characteristic of the 3-phase voltage source converter based on a new mathematical model is studied. A practical indirect current realization of the system is carried out, the closed loop regulator is designed and the regulator parameter is configured. To obtain unity power factor, a new algorithm is presented. System experiment results are provided to prove the correctness of the theoretical analysis and the simulation.

Research of high voltage RSDS triggering circuit in multi-modules capacitor discharge PFN for EML

In this paper, a compact pulsed power capacitor discharge module is considered to realize large current output for electromagnetic launching. A novel triggering circuit is proposed based on inductive adder circuit topology to provide optimal reverse current for controlling the high voltage RSDs assembly switching properly. Experimental results verified the IAT triggering circuit electrical and magnetic design.