Reference-input-based Imaginary Axis Current Estimation Method for DQ Control Strategy in Single-phase PWM Converters

For dq control strategies in single-phase pulse width modulation(PWM)converters,the-axis current must be created by imaginary axis current estimation(IACE)methods.The estimated error of the-axis current during the transient process causes d-q axis current loops to be incompletely decoupled,thereby affecting the dynamic performance of the current loop.The second-order generalized integrator(SOGI)method suffers from slow dynamic response.The fictive-axis emulation(FAE)method provides fast dynamic response but it is sensitive to circuit parameters.A reference-input(RI)-based IACE method is proposed to overcome the above shortcomings.According to the characteristic that the-axis current loop has no transient process,the-axis current is estimated by the d-q axis reference inputs.This is equivalent to introducing the-axis reference input as a feedforward term into the d-q axis current loop,so the parameter sensitivity problem is solved,and the parameter tuning is not needed.The proposed method can maintain good steadystate performance and significantly improve the dynamic performance of the current loop.Furthermore,it is straightforward and can be easily implemented in digital controllers.Comprehensive hardware-in-the-loop(HIL)experimental comparisons with the SOGI and FAE methods have been conducted to verify the correctness and effectiveness of the proposed RI-based IACE method.

Unified algorithm of single-phase active AC-DC converters and its applications

This paper discusses a novel boost single-phase active AC-DC converters, named low-end semi-controlled bridge AC-DC converter. By analysis, its topology and principle can be derived from the conventional single-phase power factor corrector （ PFC）. But it has also some differences, such as power device positions, inductor type, input voltage waveform detection and induction current detection, so its design is also different. The converter is implemented by employing two current detection approaches, i.e., current transformer detection and shunt resistor detection. Consequently, it can provide a steady DC output voltage with a low voltage ripple, approximately unitary input power factor and 2.5 kW output power. The experimental results show validity of the theoretical analysis.

Soft-switching PWM boost full-bridge converter

This paper proposes a family of PWM modulation strategies for boostfull-bridge (FB) converters. The modulation strategies can be classified into two kinds according tothe turn-on sequence of the diagonal switches. The concept of leading switches and lagging switchesis introduced to realize soft-switching. According to the soft-switching realized by the leadingswitches and the lagging switches, two kinds of soft-switching techniques for PWM boost FBconverters yield: zero-current-switching (ZCS) and zero-current and zero-voltage-switching (ZCZVS).Simulation results verify the analysis.

OPTIMAL DESIGN OF DUAL STATOR-WINDING INDUCTION GENERATOR WITH PWM CONVERTER

To minimize the reactive power of the converter of the control winding in the novel dual stator-winding induction generator based on the PWM converter, design features of the induction generator with a rectified load are proposed. The optimization method of excited capacitors to minimize the reactive power of the control winding at a variable speed is given. The calculation capacity of the machine with a diode bridge rectifier load is proposed. To achieve global searching, the integrated method with the improved real-coded genetic algorithm and the twodimensional finite element method （FEM） is introduced. Design results of the sample show that reactive power can be reduced by the method, and the converter capacity can be decreased to 1/3 of output rated power at the speed ratio of 1 ： 3, thus reducing the volume and the mass of the inverter.

Simulation on Soft-Switching PWM Converter with High Power Factor

A new PWM converter based on soft switching is introduced. The converter uses a minimum number of devices, and requires less switching operations than conventional techniques. Switching is realized solely in a ZVS (zero voltage switching) mode, therefore the loss is reduced and EMI (electromagnetic interference) is suppressed. The paper analyzes the operation of ZVS, and discusses the methods for maintaining a unit power factor and constant DC voltage. Changing the modulation index M and the phase angle θ keeps the input current in phase with the voltage. It also keeps the current sinusoidal, and ensures a constant output voltage.

An Analysis of Buck Converter Efficiency in PWM/PFM Mode with Simulink

This technical paper takes a study into efficiency comparison between PWM and PFM control modes in DC-DC buck converters. Matlab Simulink Models are built to facilitate the analysis of various effects on power loss and converting efficiency, including different load conditions, gate switching frequency, setting of voltage and current thresholds, etc. From efficiency vs. load graph, a best switching frequency is found to achieve a good efficiency throughout the wide load range. This simulation point is then compared to theoretical predictions, justifying the effectiveness of computer based simulation. Efficiencies at two different control modes are compared to verify the improvement of PFM scheme.

Novel control scheme for 3-phase PWM current-source converters under unbalanced source voltage conditions

Under unbalanced source voltage supply, considerable output second harmonics and input low-order harmonics in 3-phase PWM current-source converters (PWM-CSC) are generated. This paper proposes a new deadbeat controller based on compensation for unbalanced source voltage and current. With the proposed scheme, the second harmonics of the output current are eliminated and low-order harmonics of the source current are reduced effectively. Simulation and experimental results con- firmed the feasibility of the proposed method.

EMI Reduction in Low Input Ripple DC-DC Converter using Chaos PWM technique

This paper presents a chaotic PWM switching technique for a high boost DC-DC converter with a very low ripple at the input current.The use of a choatic PWM allows a reduction of Electromagnetic In(EMI)at the output of power converters by spreading the energy spectrum of the output voltage.In this paper a chaotic PWM,using the Chua oscillator,has been implemented in Matlab for the converter under study and a comparison with a traditional PWM control has been done.A detailed description of the generation of the chaotic carrier is presented and the effect on the output EMI mitigation has been shown.

A zero-voltage transition for three-phase double-PWM voltage-fed converter

In comparison with several zero-voltage transition （ZVT） inverter topologies, a double-PWM converter is presented using a simple ZVT topology. The rectifier and inverter of this double-PWM share a set of commutation circuit which can provide soft-switching for the power devices and the diodes. The commutation circuit consists of 1 auxiliary device, 6 resonant inductors, and 12 diodes. Its topology is simpler than the conventional auxiliary resonant converter, leading to low loss and easy control. The control strategy and resonant working modes are analyzed. Experimental results show good performance of the system.

The Design of A/D Converter Circuit Adopting the Technology of PWM

This text has expounded the working principle of realizing A/D conversion that utilizes the timer within MCU and combinesthe technology of PWM. The design of hardware circuit, improved gradual approached trial arithmetic and relevant program design arediscussed in detail. And it has analyzed the resolution of A/D converter based on the technology of PWM, etc.

Research on a Novel Inverter Based on DC/DC Converter Topology

The conventional inverters have the shortcomings of straightway conduction in transistors and the difficulty of realizing soft swit￣ching. A novel inverter based on the DC/DC converter topology is presented. The inverter is comprised of a combined Buck/Boost DC/DC converter and a bridge circuit. The front stage converter is controlled to output variable DC voltage and the bridge circuit is used to convert the DC voltage to AC output. The energy feedback technology and one circle control scheme are used t...

定频PWM控制混合桥双LLC谐振变换器研究

针对宽输出电压应用中传统频率控制LLC谐振变换器工作频率范围宽且存在较大循环电流的问题,提出1种定频PWM控制混合桥双LLC谐振变换器。根据原边侧结构的不同,所提变换器有3种拓扑结构形式,分别为半桥-半桥双LLC谐振变换器、半桥-全桥双LLC谐振变换器、全桥-全桥双LLC谐振变换器。其中,原边侧结构并联输入,2个变压器二次侧串联输出。相较于传统频率控制LLC变换器,3种拓扑形态始终在谐振频率点工作,缩小了开关频率范围;在PWM控制策略下,可以分别实现2倍电压增益、3倍电压增益和4倍电压增益以适应宽电压场合;电路中循环电流损耗低,软开关性能良好。Simulink仿真和实验结果验证了所提方案的可行性。

基于PWM软开关技术的智能充电机的设计与实现

针对由工频变压器和整流电路组成的传统充电机存在体积大、不便运输、可靠性差等缺陷,采用无工频变压器开关电源技术,按照蓄电池充电特性曲线特点,采用恒流-恒压(CC-CV)充电法,进行系统方案及主电路设计,并使用整流—Buck降压斩波模式和PWM软开关技术控制充电机电路。实验表明,与工频型充电机相比,该方法能显著延长蓄电池使用寿命。

Advanced Burst Mode Control to Reduce the Standby Power of Flyback Converter

This paper we proposed advanced burst mode control technique to reduce the standby power consumption of the switch mode power supply (SMPS). To reduce the standby power consumption, most of the converter use burst mode or skip mode control technique. However Conventional standby mode control techniques have some problems such as audible noise and poor regulation. In proposed techniques, basically, the burst mode control technique is employed to reduce the fundamental switching frequency while limiting the peak drain current. But, in proposed technique, to improve the regulation characteristic, burst period of the proposed technique is shorter than that of the conventional burst mode technique. And also, to reduce the switching loss increase due to the short burst period, burst switching signal of the proposed technique is partially skipped. By using proposed advanced burst mode control technique, calculated standby power is 0.695W while standby power of the conventional burst mode control is 1.014W.

The Usage of the Digital Controller in Regulating Boost Converter

This paper proposes the modeling and simulation technique to analyze and design a Boost converter using generalized minimum variance method with discrete-time quasi-sliding mode to adjust the converter switch through a pulse width modulation (PWM), so as to enhance a stable output voltage. The control objective is to maintain the sensed output voltage stable, constant and equal to some constant reference voltage (8 volt) in the load resistance variation (24, 48, 240) Ω and input voltage variation (20, 24, 28) volt circumstances. This control strategy is very appropriate for the digitally controlled power converter and for the system requirement accomplishment, resulting high output voltage accuracy. The performance degradation in practical implementation can be expected due to noise, PWM nonlinearities, and components imperfection. The digital simulation using MATHLAB/Simulink is performed to validate the functionality of the system.

A Dual-Mode Step-up DC/DC Converter IC with Current-Limiting and EMI Reduction Techniques

This paper presents a novel dual-mode step-up （boost） DC/DC converter. Pulse-frequency modulation （PFM） is used to improve the efficiency at light load. This converter can operate between pulse-width modulation （PWM） and pulse-frequency modulation. The converter will operate in PFM mode at light load and in PWM mode at heavy load. The maximum conversion efficiency of this converter is 96%. The conversion efficiency is greatly improved when load current is below 100 mA. Additionally, a soft-start circuit and a variable-sawtooth frequency circuit are proposed in this paper. The former is used to avoid the large switching current at the start up of the converter and the latter is utilized to reduce the EMI of the converter.

Investigation and Evaluation of Multilevel H-NPC Converter for Electrically Driven Trains

In this paper the operation of a three level H-bridge converter as well as its parallel operations is analyzed and simulated on the computer. Based on the simulation results the operating behavior between （a） a three level H-bridge neutral point clamped convener, （b） a three level back-to-back H-bridge neutral point clamped convener, （c） two three level H-bridge neutral point clamped converters parallel connected is being compared. From the simulation results it is obvious that in the first two cases the ripples, the distortion in primary and secondary winding currents, and the power factor are quite satisfactory and almost identical to each other. In the third case as compared with the first two, it is observed that current harmonics with higher amplitude appear in the primary winding of the transformer.

Fuel cell stack design and modelling with a double-stage boost converter coupled to a single-phase inverter

A comprehensive proton-exchange membrane fuel cell stack model was developed and integrated with a two-stage DC/DC boost converter.It was directly coupled to a single-phase(two levels-four pulses)inverter without a transformer.The pulse-width modu-lation signal was used to independently regulate every converter phase.The converter was modelled using a MATLAB®/Simulink®environment and an appropriate voltage control method.The analysis features of the suggested circuit were created and,through established experiments,the simulation results were verified.A single-phase(two levels-four pulses)inverter control circuit was tested and it produced a pure sinusoidal waveform with voltage control.It matches the voltage of the network in terms of amplitude and frequency.A sinusoidal pulse-width modulation approach was performed using a single-phase(two levels-four pulses)pulse-width modulation inverter.The results demonstrated an enhancement in the standard of the output wave and tuned the dead time with a reduction of 63μs compared with 180μs in conventional techniques.

Grid-Connected PV Solar Energy Converter with Active and Reactive Power Control

This work proposes a 12 kW three-phase grid-connected single stage PWM DC-AC converter destined to process the energy provided by a photovoltaic array composed of 57 KC200GT PV modules with high power factor for any solar radiation. The PWM inverter modeling and the control strategy, using dqO transformation, are proposed in order to also allow the system operation as an active power filter, capable to compensate harmonic components and react power generated by the non-linear loads connected to the mains grid. An input voltage clamping technique is proposed to impose the photovoltaic operation on the maximum power point. Simulation and experimental results are presented to validate the proposed methodology for grid connected photovoltaic generation system.

A Novel Approach to Practical Matrix Converter Motor Drive System With Reverse Blocking IGBT

a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)