RELIABLE HYSTERESIS CURRENT CONTROLLED DUAL BUCK HALF BRIDGE INVERTER

A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.

THREE-PHASE BRIDGE INVERTER FOR 9kW DOUBLY SALIENT PERMANENT MAGNET MOTOR

The three-phase bridge inverter is used as the converter topology in the power controller for a 9 kW doubly salient permanent magnet （DSPM） motor. Compared with common three-phase bridge inverters, the proposed inverter works under more complicated conditions with different principles for special winding back EMFs, position signals of hall sensors, and the given mode of switches. The ideal steady driving principles of the inverter for the motor are given. The working state with asymmetric winding back EMFs, inaccurate position signals of hall sensors, and the changing input voltage is analyzed. Finally, experimental results vertify that the given anal ysis is correct.

H6 Non-isolated Full Bridge Grid-connected PV Inverters With Low Leakage Currents

为满足非隔离光伏并网发电系统对共模漏电流的限制，提出一种六开关逆变器拓朴（H6拓扑）。所提出的H6拓扑在功率传输模态时，进网电流半个工频周期流过3支开关管，而另半个工频周期流过2支开关管，故相对于H5拓扑，降低了通态损耗，有利于热应力均衡，且仍满足续流阶段光伏电池输出端与电网脱离的要求。详细分析拓扑的工作原理，并推论给出H6非隔离光伏并网逆变器的其它3种拓扑结构；比较分析了H5拓扑、Heric拓扑和H6拓扑的损耗和成本。通过1kW通用样机平台对比验证了上述3种拓扑的效率和共模特性。实验结果表明，H6拓扑的变换效率高于H5拓扑、但略低于Heric拓扑，共模特性优于Heric拓扑、但略劣于H5拓扑。

Symmetrical dynamical characteristic of peak and valley current-mode controlled single-phase H-bridge inverter

Complex dynamical phenomenon was studied in the single phase H-bridge inverter which was controlled by either a peak current or a valley current. The state functions and the discrete iterative map equations were established to analyze the dynamical phenomenon in the single phase H-bridge inverter. The dynamical characteristics of the single phase H- bridge inverter, such as time domain waveform diagram, bifurcation diagram, and folding map, were obtained by using the numerical calculation when the circuit parameters varied in specific range. Moreover, the simulation results were obtained by using the OrCAD-PSpice software to validate the numerical calculation. Both the numerical calculation and the circuit simulation show that the symmetrical dynamical phenomenon occurs in the single phase H-bridge inverter controlled by the peak current or the valley current.

Research of Mining STATCOM Based on Hybrid Multilevel H-bridge Inverter

The paper presents a new STATCOM system based on H-bridge inverter. It can be used in mine power network. It has been commonly verified for the positive effects of SVG on the reactive power compensation and voltage fluctuation suppression. This paper focuses on a generalized structure of multilevel power converter where individual voltage sources are not necessarily the same. The cascade H-bridge consists of two cells, high-voltage cell and low-voltage cell. The high-voltage cell is responsible for voltage lifting, while the low-voltage cell is responsible for PWM modulation. If two cells are cascaded with DC voltages in a ratio of 2:1, the single-phase output voltage can reach 7 levels. Increasing voltage levels of output waveform can bring up AC current quality, optimize harmonic spectrum and enhance converter efficiency. The hybrid multilevel is characterized by per-phase series connection of a high-voltage H-bridge converter and a low-voltage H-bridge converter. Due to the different capacitor voltage, it is a key problem as to how to maintain the capacitor’s voltage at a reference level. Independent DC source can effectively ensure the DC voltage. Through the reactive power compensation technology, the three-phase voltage and current can remain at the same phase.

THD Analysis of Cascaded H-Bridge Inverter with Fuzzy Logic Controller

In recent days, the multilevel inverter technology is widely applied to domestic and industrial applications for medium voltage conversion. But, the power quality issues of the multilevel inverter limit the usage of much sensitive equipment like medical instruments. The lower distortion level of the output voltage and current can generate a quality sinusoidal output voltage in inverters and they can be used for many applications. The harmonics can cause major problems in equipments due to the nonlinear loads connected with the power system. So, it is necessary to minimize the losses to raise its overall efficiency. In this paper, a new topology of seven level asymmetrical cascaded H-bridge multilevel inverter with a Fuzzy logic controller had been implemented to reduce the Total Harmonic Distortion (THD) and to improve the overall performance of the inverter. The proposed model is well suited for use with a solar PV application. In this topology, only six IGBT switches are used with three different voltage ratings of PV modules (1:2:4). The lower number of semiconductor switches leads to minimizing overall di/dt ratings and voltage stress on each switches and switching losses. The gate pulses generated by Sinusoidal Pulse Width Modulation (SPWM) technique with a Fuzzy logic controller are also introduced. A buck-boost converter is used to maintain the constant PV voltage level integrated by an MPPT technique followed by Perturb and Observer algorithm is also implemented. The MPPT is used to harness the maximum power of solar radiations under its various climatic conditions. The new topology is evaluated by a Matlab/Simulink model and compared with a hardware model. The results proved that the THD achieved by this topology is 1.66% and realized that it meets the IEEE harmonic standards.

Capacitor Pattern H-Bridge Multilevel Inverter (CPHMLI) Using Phase Diposition Pulse Width Modulation for Grid Applications

This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.

A New Structure of Multilevel Inverter with Reduced Number of Switches for Electric Vehicle Applications

Both Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) need a traction motor and a power in-verter to drive the traction motor. The requirements for the power inverter include high peak power, opti-mum consumption of energy, low output harmonics and inexpensive circuit. In this paper, a new structure of multilevel inverter with reduced number of switches is proposed for electric vehicle applications. It consists of an H-bridge and an inverter in each phase which produces multilevel voltage by switching the dc voltage sources in series. As the number of switches are reduced, both conduction and switching losses will be de-creased, which leads to increase the efficiency of converter. The size and power consumption of driving cir-cuits are also reduced. The proposed three phase inverter can produces more number of voltage levels in the same number of the voltage source and reduced number of switches compared to the conventional inverters. This structure minimizes the total harmonic distortion (THD) of the output voltage waveforms. The structure of proposed multilevel inverter, modulation method, switching losses, THD calculation and simulation re-sults with PSCAD/EMTDC software are shown in this paper.

Graphene Bridge Heterostructure Devices for Negative Differential Transconductance Circuit Applications

Two-dimensional van der Waals(2D vdW)material-based heterostructure devices have been widely studied for high-end electronic applications owing to their heterojunction properties.In this study,we demonstrate graphene(Gr)-bridge heterostructure devices consisting of laterally series-connected ambipolar semiconductor/Gr-bridge/n-type molybdenum disulfide as a channel material for field-effect transistors(FET).Unlike conventional FET operation,our Gr-bridge devices exhibit nonclassical transfer characteristics(humped transfer curve),thus possessing a negative differential transconductance.These phenomena are interpreted as the operating behavior in two series-connected FETs,and they result from the gate-tunable contact capacity of the Gr-bridge layer.Multi-value logic inverters and frequency tripler circuits are successfully demonstrated using ambipolar semiconductors with narrow-and wide-bandgap materials as more advanced circuit applications based on non-classical transfer characteristics.Thus,we believe that our innovative and straightforward device structure engineering will be a promising technique for future multi-functional circuit applications of 2D nanoelectronics.

Minimization of Switching Devices and Driver Circuits in Multilevel Inverter

The various configurations of multilevel inverter involve the use of more numbers of switching devices, energy storage devices and/or unidirectional devices. Each switching unit necessitates the add-on driver circuit for proper functionality. Cascaded H-Bridge Multilevel Inverter requires overlapped switching pulses for the switching devices in positive and negative arms of the bridge which may lead to short circuit during the device failure. This work addresses the problems in different configurations of multilevel inverter by using reduced number of switching and energy storage devices and driver circuits. In the present approach Single Switch is used for each stair case positive output and single H-Bridge for phase reversal. Driver circuits are reduced by using the property of body diode of the MOSFET. Switching pulses are generated by Arduino Development Board. The circuit is simulated using Matlab. More so, through experimental means, it is physically tested and results are analyzed for the 5-step inverter and thereby simulation is fully validated. Consequently, cycloconverter operation of the circuit is simulated using Matlab. Moreover, half bridge configuration of the multilevel inverter is also analyzed for high frequency induction heating applications.

A Novel Multilevel Inverter Circuit for the Performance Enhancement of Direct Torque Controlled Induction Motor

Induction motor is the most sought after motor in the industry for excellent performance characteristics and robustness. Developments in the Power Electronic circuitry have revolutionised the induction motor industry leading to the developments in various control strategies and circuits for motor control. Direct Torque Control (DTC) is one of the excellent control strategies preferred by industries for controlling the torque and flux in an induction machine. The main drawback of DTC is the presence of torque ripple which is slightly more than the acceptable limit. There are various parameters that introduce ripples in the electromagnetic torque, one of them being the type of inverter circuit. There are various types of inverter circuits available and the effect of each of them in the production of torque ripple is different. This work is an attempt to identify the influence of various multilevel inverter circuits on the torque ripple level and to propose the best inverter circuit. The influence of multilevel diode clamped inverter and cascaded H bridge inverter circuits on torque ripple minimization, is analysed using simulation studies for identifying the most suitable multilevel inverter circuit which gives minimum torque ripple. The results obtained from the simulation studies are validated by hardware implementation on 0.75 kW induction motor.

Performance Metric of Z Source CHB Multilevel Inverter FED IM for Selective Harmonic Elimination and THD Reduction

This paper focuses on a Z source cascaded multilevel inverter which is designed to minimize harmonics in the output voltage. A balanced dc-link peak voltage can be achieved. The power generation module is built by PV panels which are connected to Z-Source Cascade H-bridge inverter. Cascaded multilevel inverter can achieve the distributed maximum power point tracking to increase the system efficiency and achieve high voltage/high power grid tie without a transformer. This paper analyzes the different PWM switching scheme and the operating states of a ZSI module and comparison is made with different PWM and total harmonic distortion of various PWM schemes.

Design and Evaluation of Solar Inverter for Different Power Factor Loads

This paper analyzes and compares the performance of a new inverter topology with two types of input sources: 1) Solar PV source and 2) Ideal dc source (battery). The simulation is done in SIMULINK/MATLAB Software. It is shown that when the solar panel is connected, spikes are obtained in output voltage waveforms. These spikes are eliminated by inserting a capacitor. The capacitor is chosen for a particular power factor which is optimum with respect to cost, size and power quality. Total Harmonic Distortion, Active Power, Reactive Power, RMS Voltage and RMS Current are measured for different load power factor. Finally these results are compared with those obtained using battery with same input voltage magnitude. This Paper shows that for Solar Panel Circuit, THD, P and Q are less for 0.8 and above power factor, however below 0.8 PF, the THD, active and reactive power transfer are more. This means that the performance of Solar Panel in the proposed circuit topology is seen to be better as compared to the same circuit with battery within a range of power factor.

New Approach of Multi-Cell Stacked Cell Inverter for Solar Photovoltaic System

In this paper, a new inverter topology dedicated to isolated or grid-connected PV systems is proposed. This inverter is based on the structures of a stacked multi-cell converter (SMC) and an H-bridge. This new topology has allowed the voltage stresses of the converter to be distributed among several switching cells. Secondly, divide the input voltage into several fractions to reduce the number of power semiconductors to be switched. In this contribution, the general topology of this micro-inverter has been described and the simulation tests developed to validate its operation have been presented. Finally, we discussed the simulation results, the efficiency of this topology and the feasibility of its use in a grid-connected photovoltaic production system.

多电平级联H桥逆变器通用型离散模型及分岔与混沌行为特性分析

多电平级联H桥逆变器内部功率器件多、等效开关频率高、开关组合状态繁杂、离散数学模型建立难度大,其分岔、混沌动力学行为难以进行系统性分析。基于虚拟遍历法建立了具有N个单元的多电平级联H桥逆变器通用型离散映射数学模型;引入对交流变量跟踪性能更佳的准比例谐振控制器,并重点分析了比例增益、谐振增益、单元数量N变化以及主电路和控制电路中其他参数变化情况下的分岔、混沌行为特性;对比分析了引入混沌抑制前后系统稳定性变化情况。从方法论角度分别采用根轨迹图和折叠图验证了稳定性分析结果的正确性,并通过PSIM仿真和实验验证了相关结论的正确性和抑制分岔与混沌行为的有效性。

基于自抗扰控制的H桥逆变器的混沌研究

为了解决新能源发电系统逆变器出现混沌的问题,提出了一种基于自抗扰控制的H桥逆变器的调节方案。针对处于混沌状态的逆变器的稳态和动态特性差的现象,构建了逆变器的离散模型,并通过建立跟踪微分器、扩张状态观测器以及状态误差反馈控制律进行混沌控制。通过分岔图、折叠图以及仿真分析,结果可知基于自抗扰控制的H桥逆变器比基于比例控制的H桥逆变器的稳定范围扩大了45%,有效地抑制了混沌现象的发生。通过分析可得出:该控制策略对系统的混沌行为能够进行抑制,拓宽了系统稳定工作范围。

正弦波逆变器波形稳定混合控制策略研究

受蓄电池放电能力和实际电压限制,逆变器在稳定运行状态下,若瞬间断开或连接大负载,会使负载电压出现较大波动,严重时损坏设备。若直流母线电压较低,则逆变器输出的正弦波波形易产生削顶削底现象,对感性负载有影响。针对该问题,提出有效值闭环控制与定点电压闭环控制相结合的混合控制策略,在电压高于320 V时,采用定点电压闭环控制方式;若直流母线电压低于320 V,采用有效值闭环控制方式。经过仿真分析和实验验证,采用该混合控制策略,逆变器能够快速响应负载变动并使正弦波波形不会产生畸形。

无线电能传输系统全桥逆变器性能优化研究

针对无线电能传输系统中全桥逆变器开关管的开通和关断存在振铃,能量传输波形纹波大,导致逆变器温升大和工作不稳定的问题,进行了电路建模分析,开展了全桥逆变器性能优化研究。首先,对逆变器开关管驱动电路进行了简化,建立了RLC串联谐振电路模型,分析了驱动电路结构参数对逆变器性能的影响规律,得出了优化方法;其次,分析了逆变器纹波大的问题,给出了优化方法;最后,搭建了300 W无线电能传输系统并进行实验。实验结果验证了优化方法的正确性和有效性,逆变器性能得到了改善,温升得到了有效控制,系统传输效率提高了5.3%,整机效率达到了89.3%。

混合级联H桥逆变器的新型SHEPWM功率均衡控制策略

对于直流侧电压比为1∶1∶2的混合级联H桥逆变器,传统的指定谐波消除脉宽调制法(SHEPWM)存在各单元间输出功率不均衡问题,因此,提出一种双层功率均衡调制策略。首先,通过对消谐方程组中的基波幅值方程表达式进行等效拆分,使2个低压H桥单元的输出电压基波幅值之和与高压H桥单元的输出电压基波幅值相等,实现了高低压H桥单元间的功率均衡,即外层功率均衡。其次,利用逻辑运算的方法对低压单元的初始驱动信号进行逻辑重组,实现2个低压单元间的功率均衡,即内层功率均衡;然后使用改进的实数型遗传算法(IRCGA-2)求出消谐方程组的解,消除指定的谐波,得到高质量的输出电压。最后,通过仿真和实验证明了调制策略的正确性与有效性。