Three-level Diode Clamped Inverter Research Articles

Solar Based Multilevel Inverter f o r BLDC Motor Drive

The BLDC motor is widely utilized in high power and low voltage applications because to its simple construction, great efficiency, low maintenance requirements, and low cost .Furthermore, considering their size, they have a lot of torque and power output. The BLDC motor is powered by an alternating current source and is operated straight from the AC supply port, despite being a DC motor in this case. The main drawback is that any disruptions in the source will have an impact on the applications that use BLDC motors in the industrial context. So, to avoid this, there should be a converter and an inverter intermediary between the motor and the source. One of three methods can be used to drive the BLDC motor. 1. Two-level inverters based on pulse width modulation (PWM). 2. An multiple-level working inverter. 3. A multilevel inverter with neutral clamping. Using a multicarrier PWM technique, the suggested inverter may lower the output signal's harmonic content. It is capable of generating very good motor currents. In this instance, a three-level diode clamped multilevel inverter can be used to accurately control the speed of a BLDC. This study's primary goal is to demonstrate how to run a BLDC drive with an inverter to lower harmonics. A diode clamped multi-level inverter is a device that converts voltage to current. An improved version of this strategy is provided by this research. Using the MATLAB Simulink software tool, one can assess the system's overall effectiveness by simulating the neutral clamp multilevel inverter-based drive system's functioning. In the event of a power outage, the entire application will cease to function and generate output. Under order to increase the output and supply reliability of power, renewable energies must be used under these circumstances. There are many renewable energy sources available; however solar photovoltaic systems are the better option because of their benefits over traditional power sources. A diode clamped multi-level inverter was used. A diode clamped multi-level inverter was used to drive the BLDC.

Formation of the Spectral Composition of the Output Voltage of Converters for Nuclear Magnetic Resonance

In this paper, we consider the construction of an asynchronous control system for semiconductor converters for nuclear magnetic resonance. The relevance of research in this direction, main problems that arise during the construction of these systems are shown. Derived the mathematical model of the inverter, on the basis of which a control system with asynchronous pulse-width modulation is constructed. Proposed an equivalent converter circuit with a constant structure, constant parameters, and an equivalent EMF generator. Established correspondence between the equivalent circuit of the converter and its mathematical model in the form of differential equations. On the basis of mathematical equations, a structural diagram of the converter with a control system was developed and the principle of operation of the device was described according to it. To develop an algorithm for the control system, the dependence of the frequency change relative to the resonant frequency on the phase shift between the current through the filter and the voltage on the antenna circuit is determined. For which the model was built in Simulink and the corresponding simulation was carried out. Numerical dependences of reference signal frequency change and phase shift were obtained. The increase in efficiency of device for nuclear magnetic resonance is considered due to the use of multilevel inverters with tuning the frequency of operation to the frequency of the resonant circuit. Simulation of a three-level diode-clamped inverter showed that when the capacitance of the resonant circuit changes and, therefore, the resonant frequency of the circuit, the input current increases. The work obtained specific numerical dependencies. Time diagrams of voltages and currents on the main elements of the converter are given, which illustrate the implementation asynchronous pulse-width modulation in the control system. After working out the automatic frequency control algorithm, the increase in current consumption can be leveled off. The simulation results also show that it is possible to reduce the amplitude of the third harmonic. The disadvantages of the proposed system include the fact that the frequency of the converter is adjusted at each subsequent period of its operation. At the same time, the parameters of the filter can change again, which leads us to believe that adjusting the frequency will never give a 100% result, but will only allow to get as close as possible to the set parameters of the sounding signal. The work also indicates that it is possible to improve the spectral composition of the probing voltage generated by the converter by using more levels of a diode-clamped multi-level inverter. However, increasing the number of levels reduces the action speed of the system and complicates the control system itself. Therefore, the need to maintain a balance between the number of levels of the inverter and the complexity of the system is indicated.

A New Non-Isolated Active Quasi Z-Source Multilevel Inverter With High Gain Boost

This paper proposes a three-level diode clamped active impedance source inverter (AIS-TLI) based on the quasi Z-source inverter (qZSI). Apart from having minimal components and the inherent benefits of three-level qZSIs, such as single-stage buck-boost capability, shoot-through (ST) immunity, and continuity of input current, the proposed topology has a higher boost capability and excellent efficiency. In addition, the inverter bridge has a higher modulation index, which improves the quality of the output waveform and necessitates less inductance. The proposed topology provides common ground between input and output terminals, which effectively eliminates leakage current in PV-powered single-phase systems. This paper describes the different operating modes principle, dynamic analysis, steady-state analysis, and parameter selection instructions for the proposed in-depth. Furthermore, the suggested inverter’s benefits and limitations are compared to the traditional (q)ZSIs and some other AIS-TLIs. Finally, modeling and experimental results are used to confirm the effectiveness of the suggested topology.

A grid-tied PV-fuel cell multilevel inverter under PQ open-loop control scheme

Power generating entities’ connection to utility grids requires power converters to achieve high efficiency and low injected current harmonic distortion. The control of the power converter plays a crucial role in the grid-tied power converter’s performance. Various control techniques for grid-tied inverters ranging from classical to intelligent are introduced in several exist. Evaluating the current state and trend in grid-tied power inverters and related control methods, research shows that most works in this area focus on grid integration using the close-loop and other advanced control approaches. This is because these control methods are preferred since they provide adequate performance in case of uncertainties in the system. This investigation can aprove that PQ open-loop control technique can operate sufficiently and cost-effectively in grid-tied renewable and alternative power systems under normal operating conditions. Hence, this paper aims to assess the performance of a centralized single-stage grid-tied three-level diode clamped inverter connected to a PV-Fuel cell unit. An active and reactive power open-loop control scheme is employed to operate the inverter and achieves a current harmonic distortion below 5%. The system comprises a 150 kW/700 V PV, a 150 kW/1400 V fuel cell, a 265 kW multilevel inverter operating at a rated voltage of 415 V, and an LCL filter. Two operating scenarios are adopted to investigate the system’s responses further. In the first scenario, a local load of 509.2 kW is supplied from the PV-fuel cell inverter. The load also receives the grid’s power to meet the demand as the PV-fuel cell inverter provides only 265 kW. Whereas in the other scenario, the PV-fuel cell unit provides power to supply a local load while transporting the surplus to the grid. The results reveal the developed model’s good performance with a current harmonic distortion of 0.33%.

Diagnosis and localization of fault for a neutral point clamped inverter in wind energy conversion system using artificial neural network technique

Introduction. To attain high efficiency and reliability in the field of clean energy conversion, power electronics play a significant role in a wide range of applications. More effort is being made to increase the dependability of power electronics systems. Purpose. In order to avoid any undesirable effects or disturbances that negatively affect the continuity of service in the field of energy production, this research provides a fault detection technique for insulated-gate bipolar transistor open-circuit faults in a three-level diode-clamped inverter of a wind energy conversion system predicated on a doubly-fed induction generator. The novelty of the suggested work ensures the regulation of power exchanged between the system and the grid without faults, advanced intelligence approaches based on a multilayer artificial neural network are used to discover and locate this type of defect; the database is based on the module and phase angle of three-phase stator currents of induction generators. The proposed methods are designed for the detection of one or two open-circuit faults in the power switches of the side converter of a doubly-fed induction generator in a wind energy conversion system. Methods. In the proposed detection method, only the three-phase stator current module and phase angle are used to identify the faulty switch. The primary goal of this fault diagnosis system is to effectively detect and locate failures in one or even more neutral point clamped inverter switches. Practical value. The performance of the controllers is evaluated under different operating conditions of the power system, and the reliability, feasibility, and effectiveness of the proposed fault detection have been verified under various open-switch fault conditions. The diagnostic approach is also robust to transient conditions posed by changes in load and speed. The proposed diagnostic technique's performance and effectiveness are both proven by simulation in the SimPower /Simulink® MATLAB environment.

Model-Based Design and Experimental Validation of Control System for a Three-Level Inverter

Considering the disadvantages of the traditional development pattern in an embedded control system for an inverter, that is, the single-process thinking and separation of software and hardware, a novel method, which is a model-based design, for developing a double closed-loop control system for the diode-clamped three-level inverter was proposed. System control models, including the PWM control algorithm model, the voltage control model, the neutral-point potential balancing model, and the frequency control model, were built with the MATLAB platform. The code-generation capacity and the operation effect were verified through a series of tests. The inverter with diode clamp and neutral-point potential control was developed. Codes were generated automatically and downloaded to the eZdsp28335 control chip. Experimental waveforms of the phase voltage, line voltage and current were analyzed under regulating the voltage and frequency. The experimental results demonstrate that the models and the generated codes are correct. Further studies have proven the feasibility of the system development model.

Improvement of torque undulation in BLDC using SEPIC and common end diode clamped three-level inverter

Improvement of torque undulation in BLDC using SEPIC and common end diode clamped three-level inverter

A Design of Three-level Inverter Based on PCI Control

To solve the problem that the PI-controlled three-level inverter can’t achieve zero steady-state error on AC, a closed-loop control scheme using the PCI controller is proposed. The voltage and current double closed-loop control scheme is adopted. The circuit of diode-clamped three-level inverter is selected as the controlled object. And the PCI controller is designed. The zero steady-state error of three-level inverter based on the PCI control is analyzed in detail. Finally, the closed-loop control system of three-level inverter is simulated on the MATLAB/Simulink platform. The results show that the PCI control has good dynamic response ability and can accurately track various sudden loads. And then the correctness of theoretical analysis is verified.

A Grid-Tied Fuel Cell Multilevel Inverter with Low Harmonic Distortions

As a result of global energy demand increase, concerns over global warming, and rapid exhaustion of fossil fuels, there is a growing interest in energy system dependence on clean and sustainable energy resources. Attractive power technologies include photovoltaic panels, wind turbines, and biomass power. Fuel cells are also clean energy units that substitute power generators based on fossil fuels. They are employed in various applications, including transportation, stationary power, and small portable power. Fuel cell connections to utility grids require that the power conditioning units, interfacing the fuel cells and the grids, operate accordingly (by complying with the grid requirements). This study aims to model a centralised, single-stage grid-tied three-level diode clamped inverter interfacing a multi-stack fuel cell system. The inverter is expected to produce harmonic distortions of less than 0.5% and achieve an efficiency of 85%. Besides the grid, the system consists of a 1.54 MW/1400 V DC proton exchange membrane fuel cell, a 1.3 MW three-level diode clamped inverter with a nominal voltage of 600 V, and an inductance-capacitance-inductance (LCL) filter. Two case studies based on the load conditions are considered to assess the developed system’s performance further. In case 1, the fuel cell system generates enough power to fully meet this load and exports the excess to the grid. In the other case, a load of 2.5 MW was connected at the grid-tied fuel cell inverter’s output terminals. The system imports the grid’s power to meet the 2.5 MW load since the fuel cell can only produce 1.54 MW. It is demonstrated that the system can supply and also receive power from the grid. The results show the developed system’s good performance with a low total harmonic distortion of about 0.12% for the voltage and 0.07% for the current. The results also reveal that the fuel cell inverter voltage and the frequency at the point of common coupling comply with the grid requirements.

Design and Analysis of Dual Output Three Level Inverter with Reduced Switch Count Topology

The multilevel inverter is widely used for medium voltage and high power applications. However, the application is limited due to the need for more number of switches, diodes and the system complexity. The proposed inverter is a hybrid topology with two-level and three-level diode clamped multilevel inverter structure with a reduced number of switches, diodes and gate driver circuits for dual output, which reduces system cost and complexity. In general, diode clamped multilevel inverter needs 24 switches to control dual output. In this paper, it was reduced as 15 switches and 12 switches by sharing of middle switches. The simulation was carried out by MATLAB Simulink and the hardware results were compared with simulation results. Also, modulation index, switching frequency and different topology with R, and RL loads were discussed and compared. The experimental plan was developed as per the Box–Behnken method and the experiments were carried out. The results were statistically analyzed and its significance was tested.

Design and simulation of three-level SVPWM based on FPGA

After expounding the overall design of the three-level SVPWM principle and algorithm, the SVPWM top level module using FPGA is created. And A/D conversion module, the Clarke transformation module, the adjacent vector function time module and the triangle carrier module are also established. Quartus II is used to simulation. And compared with the simulation results of MATLAB, the simulation waveforms are consistent, which verifies the correctness of the simulation results. Taking the diode clamped three-level inverter as the research object, the simulation waveforms of the different modulation M are compared, and the correctness of the three-level SVPWM control strategy is further verified.

Unified Power Quality Conditioner using PV Fed SVPWM based Multilevel Converters for Power Quality Improvement

This paper presents a solar photovoltaic based unified power quality conditioner (PV-UPQC). The proposed system consists of a shunt compensator (ShC), series compensator (SeC) and PV array connected in parallel to a common dc-link. A three-level diode clamped multilevel inverter configuration is used as shunt and series converters. The SVPWM technique provides reduction in the common mode voltage and the balancing of the dc link voltage. The shunt compensation converter extracts power from PV array and provides compensation for load harmonic currents. The series compensation converter compensates for the power quality (PQ) problems such as grid voltage sags/swells and source harmonic voltages. The proposed system utilizes space vector pulse width modulation (SV-PWM) in multilevel converter topology for the mitigating the power quality problems using PV-UPQC. The proposed system improves PQ and also utilize RES, it also simultaneously improves both current and voltage disturbances. The performance of the system is analyzed in MATLAB/Simulink for nonlinear load conditions.

Decoupled Power Flow Control of a Single Stage Grid Connected Pv System With Multilevel Inverter

With the wide installation of solar PV array in respect of other renewable power generation, there is a scope of feeding the surplus power to grid for better and economic power utilisation. The foremost objective of this paper to independent regulation of real and reactive power flow of single stage grid coupled PV system using multilevel inverter. Vector control scheme has been implemented in direct and quadrature reference frame which is synchronously rotating with the frequency of the grid. Two current control loop has been used, one for d-axis and other for q-axis to regulate the current inserted into the grid such that it has low total harmonic distortion and in phase with the grid voltage. In addition to that, a DC voltage control loop has also been implemented to operate the inverter at the desired DC link voltage that is the DC voltage corresponding to maximum power, which is obtained by the MPPT algorithm. Grid coupled inverters have extensive usage in the area of distributed generation and power eminence improvement. The above scheme employs a three-phase three-level Diode clamped multilevel inverter to improve the current injected to grid.

Research on neutral-point potential control of a three-level inverter

<p>Diode-clamped three-level inverters have been widely used in high voltage and high power fields because of their unique advantages. Nowadays, diode-clamped three-level inverters have become a research hotspot. In order to reduce the content of energy harmonics injected into the power grid by the inverter system, the neutral point potential needs to be controlled. This paper proposes a control method based on a proportional controller. The voltage sector was redefined and the design of the proportional controller was completed. In combination with the introduction of a new PWM technology, a smooth control of the midpoint potential was achieved. The effectiveness of the method is verified by simulation in MATLAB<em></em></p>

Modeling and Simulation of Photovoltaic Grid-connected Inverter

Based on the topology of diode clamped three-level inverter, this paper introduces the working principle and control method of the inverter. This paper focuses on the midpoint potential balance problem and PWM control method of Diode-clamped three-level inverter and the SVPWM control method developed thereby. In this paper, the analysis of inverter topology and control method is focused on the maximum power point tracking problem and phase-locked loop problem in photovoltaic grid-connected process. This paper proposes a complete system for photovoltaic grid connection using inverters. At the end of this paper, the results of simulation and analysis of the system using computer software are given.

Soft-Switched Interleaved DC/DC Converter as Front-End of Multi-Inverter Structure for Micro Grid Applications

An isolated four channel dc/dc converter with zero voltage switching is proposed as the front-end of multiple inverter structures to integrate renewable and other low voltage energy sources to micro grids. The interleaving technique is adopted to connect each module of proposed converter to a common dc source. This dc source can be a fuel cell stack, PV panels, battery, or any other low voltage dc source. All four channels are interleaved and a phase shift of 90° is provided between the gate signals of each channels, which reduces the input current ripple. The output port of the proposed converter provide four isolated and regulated dc voltages. These isolated dc sources can be connected in series or parallel or series-parallel manner to obtain required dc-link voltage of various inverter structure. Issues like capacitor voltage balancing of diode clamped multilevel inverters can overcome through the proposed converter. By incorporating a coupled inductor for isolation and energy storage along with voltage multiplier circuit, the proposed converter can achieve higher voltage step up with lower turns ratio and lower voltage stress at moderate duty ratio. Hence, mosfets of low voltage rating (low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> (ON)) can be utilized to reduce conduction loss. A 2 kW prototype of the proposed interleaved dc/dc converter is developed and tested with diode clamped three-level inverter, five-level inverter, and three-phase two-level inverter to verify the design.

Design and software implementation of solid state transformer

The work presented in this paper concerned with the analysis, design and software implementation of the Solid State Transformer as an alternative to the conventional power transformer. The proposed transformer aims to perform the same task as the conventional one with additional facilities and advantages. Three stages are considered to configure the Solid State Transformer. The first stage which is known as input stage and implemented using Vienna rectifier which converts the AC voltage of the main supply to a DC voltage. The second stage (isolation stage) step down the DC voltage to a lower level DC voltage. This stage consists of a single – phase five-level diode clamped inverter, 1 KHz step – down transformer and fully controlled bridge rectifier. The output stage (third stage) is a three-phase three-level diode clamped inverter which converts the low level DC voltage to a three-phase, 50 Hz AC voltage. Model Predictive Current Control has been employed for driving transformer’s stages. The gating signal is produced directly when the given cost function is minimized, therefore there is no need of any modulator. Behavior of the proposed structure is achieved by simulation which shows high quality power conversion with low Total Harmonic Distortion.

Commutation Torque Ripple Reduction in the BLDC Motor Using Modified SEPIC and Three-Level NPC Inverter

This paper presents a new power converter topology to suppress the torque ripple due to the phase current commutation of a brushless dc motor (BLDCM) drive system. A combination of a three-level diode clamped multilevel inverter (3-level DCMLI), a modified single-ended primary-inductor converter (SEPIC), and a dc-bus voltage selector circuit is employed in the proposed torque ripple suppression circuit. For efficient suppression of torque pulsation, the dc-bus voltage selector circuit is used to apply the regulated dc-bus voltage from the modified SEPIC during the commutation interval. In order to further mitigate the torque ripple pulsation, the 3-level DCMLI is used in the proposed circuit. Finally, simulation and experimental results show that the proposed topology is an attractive option to reduce the commutation torque ripple significantly at low- and high-speed applications.

Hysteresis SVM for Coupled Inductor Z Source Diode Clamped 3-level Inverter based Grid Connected PV System

Due to its advantages such as it can defeat problems such as leakage current and insertion of DC in the grid and provides low stress on power devices, Diode clamped three-level inverter (DCTLI) is habitually used in transformerless photovoltaic (PV) connected to grid network. But it still has a problem of shoot-through which dwells in its legs, so its operation not reliable. Z source network is employed to permit operation without shoot through risk and improve its reliability. Coupled inductors are replace line transformers in to attain lower cost, reduced size, and improved its reliability and efficiency. Coupled inductor which avoids leakage current problem and losses. It employs coupled inductor z source diode clamped three level inverter (CI-Z-DC-TLI) to boost the voltage and further improve the reliability of the system by preventing the shoot through the problem. The proposed system assures that common-mode voltage and shoot-through risk is avoided. Moreover, controlling DC-TLI with Hysteresis SVM algorithm which improves output voltage and current control. Simulation and experimental results of this proposed system were analyzed using MATLAB environment and FPGA hardware.

Phase-Shift-Controlled Isolated Buck-Boost Converter With Active-Clamped Three-Level Rectifier (AC-TLR) Featuring Soft-Switching Within Wide Operation Range

An active-clamped three-level rectifier (AC-TLR) is derived from the diode-clamped three-level inverter, by replacing the active switches and the diodes in the three-level inverter with the diodes and active switches, respectively. Novel isolated buck-boost converters, featuring single-stage conversion and soft-switching within wide operation range, are developed based on the proposed AC-TLR. By utilizing the AC-TLR, the voltage stress on the power devices and passive components, including the rectifying diodes, the active-clamping switches, the flying capacitor, and output filter capacitors, is reduced to the half of the output voltage. Low-voltage rating switching devices with better switching and conduction performances and a transformer with reduced turns ratio and parasitic parameters are used to enhance the efficiency. The full-bridge isolated buck-boost converter with the proposed AC-TLR is analyzed in detail as an example. An optimized phase-shift control strategy is employed to realize isolated buck and boost conversion. Soft switching of all of the switching devices in both the primary- and secondary-side circuits is achieved within the whole operation range by using the proposed AC-TLR and the phase-shift control strategy. Experimental results on a prototype with 380-V output verify the effectiveness of the proposed AC-TLR and its derived isolated buck-boost converters.