Two-level Inverter Research Articles

Fixed Switching Frequency Model Predictive Control for Parallel Inverters in Microgrids

A Fixed-Switching-Frequency Model Predictive Control (FSF-MPC) for Master-Slave inverters in microgrids is proposed in this paper. The Master is a three-phase, two-level inverter with an LC filter, while the Slave is a three-phase, two-level inverter with an LCL filter. The inverters are connected in parallel in a microgrid, composed of different loads. The voltage and current inner control loops of the Master-Slave FSF-MPC are presented for both inverters. Then, two modes of operation are proposed: grid-connected and islanded, and the primary control for both cases is developed. Finally, Hardware-in-the-Loop (HIL) results are presented for different operational conditions of the microgrid with load-related disturbances. The HIL results validate the good performance of the proposed Master-Slave FSF-MPC, including fast dynamic response, multi-objective control, and fixed switching frequency.

On-line junction temperature identification of converter power devices

Abstract Traction converters often fail or age due to long operation hours, complex conditions, and frequent braking, mainly caused by overheating or temperature fluctuations. Monitoring the temperature at the junction of power device is crucial for system reliability. To achieve this, the electric-heat coupling models of IGBT are studied. Models for IGBT’s switching and conduction processes were created using its data sheet, yielding a power loss model linked to junction temperature. A Foster thermal network model for IGBT was then established, deriving the equation for temperature change when losses act as heat sources. Combining these models, an electric-heat coupling model was built on the SIMULINK platform, applied to predict and simulate junction temperature in a two-level inverter, generating a temperature-time image. Finally, an experimental test platform for a two-level SVPWM-modulated inverter was set up, using an infrared sensor to measure IGBT’s steady-state junction temperature. This was compared with simulation results to verify the model’s accuracy.

Hybrid Overmodulation Strategy for Dual Two-Level Inverter With Arbitrary DC-Bus Voltage Distribution

Hybrid Overmodulation Strategy for Dual Two-Level Inverter With Arbitrary DC-Bus Voltage Distribution

Expanded virtual vector-based model forecastable control strategy for three-phase two-level inverters

Abstract A three-phase, two-level inverter based on model forecastable control has good transient performance but poor steady-state performance. Considering the limitation of a limited number of discrete voltage vectors in a two-level inverter topology, this paper proposes a virtual vector model prediction method based on the analysis of a time-stepped forecasting model for a three-phase grid-connected inverter. First, three fixed virtual voltage vectors are constructed in each sector, and the action time of the required fundamental vector is found. Then, the cost function is constructed, and the optimum is selected among the virtual and fundamental voltage vectors in each sector. Finally, a hardware-in-the-loop experiment was carried out based on the PE-Expert4 experimental platform developed by Myway Co., LTD. The results show that the proposed virtual vector model forecastable control strategy can effectively improve the transient and steady-state performance of three-phase two-level inverters.

A single-phase grid-tied extendable-level inverter for renewable energy applications

The extraction of power from green energy sources (GES) has rapidly popularized owing to increasing energy demands, depletion of fossil fuels and growing concerns about climatic changes. Grid-tied multilevel inverters are critical components in the integration of green energy sources into the power grid and offer numerous benefits over standard two-level inverters. These benefits include superior power quality, diminished harmonic distortion, and the potential to utilize high power levels efficiently. A single-phase Grid-Tied Extendable-Level Inverter (GTELI) for green energy applications is demonstrated in this paper. The GTELI offers superior power quality and distortion-free output relative to existing grid-tied multilevel inverters and hence is an excellent choice for extracting power from sustainable energy sources. To ensure efficient utilization, the extracted power from GTELI is to be integrated into the supply grid. A new current control algorithm for the GTELI is also proposed in this paper. Using this current control technique a grid control technique is established to modulate the power flow to the grid. The proposed GTELI achieved sinusoidal grid voltage and injected current with minimised harmonic distortions of 1.6% and 2.7% respectively, which comply well with the tolerable range of the IEEE 519 standard.

An Experimental Investigation on VSI-fed Induction Motor using Xilinx ZYNQ-7000 SoC Controller

In medium voltage and high-power drive applications, pulse width modulation (PWM) techniques are widely used to achieve effective speed control of AC motors. In real-time, an industrial drive system requires reduced hardware complexity and low computation time. The reliability of the AC drive can be improved with the FPGA (field programmable gate array) hardware equipped with digital controllers. To improve the performance of AC drives, a new FPGA-based Wavect real-time prototype controller (Xilinx ZYNQ-7000 SoC) is used to verify the effectiveness of the controller. These advanced controllers are capable of reducing computation time and enhancing the drive performance in real-time applications. The comparative performance analysis is carried out for the most commonly used voltage source inverter (VSI)-based PWM techniques such as sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) for three-phase, two-level inverters. The comparative study shows the SVPWM technique utilizes DC bus voltage more effectively and produces less harmonic distortion in terms of higher output voltage, flexible control of output frequency, and reduced harmonic distortion at output voltage for motor control applications. The simulation and hardware results are verified and validated by using MATLAB/Simulink software and FPGA-based Wavect real-time controller respectively.

Three-Level Inverter: Advancing Voltage Control in Power Systems for Sustainable Energy Management

This study delves into the Three-Level Inverter, a notable innovation in power systems known for its enhanced voltage management features in comparison to conventional two-level inverters. By providing more voltage levels, it improves waveform control, which is essential for maintaining stability in the changing global energy environment. The inverter effectively tackles voltage instability concerns by using sophisticated modulation techniques, as shown by oscilloscope analysis and simulation results. The study's implications have a wide range of applications, including solar power systems and electronic device power supply, highlighting its social influence and potential for practical use in energy conversion.

A Novel Graphical Technique for Multiple Harmonic Mitigation in a Two-Level Inverter With Only Two Switching Angles

A Novel Graphical Technique for Multiple Harmonic Mitigation in a Two-Level Inverter With Only Two Switching Angles

The wind turbine's direct power control of the doubly-fed induction generator

The study suggests a comprehensive approach to modeling and controlling variable-speed wind turbine systems that utilize doubly fed induction generators (DFIGs). To make sure that energy is transferred efficiently between the DFIG rotor and the grid, a two-level inverter with perfect bidirectional switches is used. Using the tip speed ratio algorithm and taking into consideration the randomness in wind speed, the maximum power at the wind turbine is optimized. Then, the control strategy utilizes direct power control (DPC) due to its various advantages. The advantages of employing this control technique are manifold. Firstly, it eliminates the necessity for rotor current control loops. Secondly, it obviates the need for controllers such as PI controllers to manage torque and flux. Furthermore, it has yielded exceptional simulation results when implementing direct power control (DPC) within the MATLAB/Simulink environment, specifically in the context of a doubly fed induction generator (DFIG) wind power system.

Enhancing power conversion efficiency in five-level multilevel inverters using reduced switch topology

This paper presents extensive research on improving the power conversion efficiency of five-level multilevel inverters (MLIs) by utilizing a reduced switch topology. MLIs have received an abundance of focus because of their ability to generate high-quality output waveforms and have better harmonic outcomes than traditional two-level inverters. The high number of switches in MLIs, on the other hand, can result in increased power losses and lower overall efficiency. In this paper, a novel reduced switch topology for five-level MLIs, which is having five switches is proposed with the aim of minimizing power losses while preserving superior performance due to lesser number of switches. To achieve efficient power conversion, the proposed topology employs advanced pulse width modulation control strategies and optimized switching patterns. The simulation results show that the minimized switch topology improves the power conversion efficiency of the five-level MLI, resulting in lower losses and better overall system performance. The total harmonic distortion (THD) value of the output current has been reduced to 7.12% and the efficiency has been achieved to 96.92%. The findings of this investigation help to advance MLI technology, allowing for more efficient and reliable power conversion in a variety of applications such as renewable energy systems, electric vehicles, and industrial drives.

An energy efficient control method of a photovoltaic system using a new three-phase inverter with a reduced common mode voltage

This paper presents a new energy-efficient space vector pulse width modulation (SVPWM) for controlling the switches of a New three-phase inverter (NTPI) for photovoltaic (PV) applications to reduce switching losses, the peak value, and the dv/dt of the common mode voltage (CMV) with fewer number of switches. The proposed system offers a reliable operation in PV energy system with less leakage current and increased efficiency because of the reduction of the CMV, the source of leakage current in PV inverter-based application. Moreover, this also optimizes the operation of electric vehicle application with lower bearing failure. The performance of the proposed system with the new SVPWM is evaluated to the existing PWM in the literature, as well as the active zero state pulse width modulation (AZSPWM) of the two-level inverter introduced under identical conditions. Experiments and MATLAB simulations have both been used in this study.

Solar PV based seventeen level reduced switch symmetrical multilevel inverter topology fed induction motor

Multilevel inverters have received a lot of interest in recent years due to their ability to deliver more voltage levels than typical two-level inverters. Because of this property, multilevel inverters can produce output waveforms that closely resemble sinusoidal waveforms, lowering harmonic distortion dramatically. The emergence of reduced switch symmetrical multilevel inverter topologies has developed the curiosity of many different power conversion systems. These new topologies offer numerous advantages, including greater output voltage quality, fewer harmonic distortions, and increased power conversion efficiency. The inclusion of these inverters in the feeding of induction motors is one of their many prominent uses. A 17 levels of multi-level inverter (MLI) topology is presented with reduced switch count and harmonic reduction for power quality improvement. The inverter is fed by isolated equal photovoltaic panels which act as direct current or DC source. To reduce complexity, switching pulses are generated using hybrid pulse width modulation technique which is designed as controller. Through the use of MATLAB/Simulink, the performance assessment of a unique cascaded multilevel inverter-based reduced switch symmetrical inverter feeding an induction motor drive has been verified. The harmonic distortion with reduced switches obtained is 7.47% which is comparatively less than when compared with conventional cascaded H-bridge topology.

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.

A Space Vector Modulation Strategy for Improving Voltage Transfer Ratio of Multi-Phase Inverter

In the five-phase-inverter adjustable speed system, a five-phase two-level inverter usually adopts the nearest-two vector SVPWM (NTV-SVPWM) or the nearest-four vector SVPWM (NFV-SVPWM). The former one has a high-output-current harmonic, which increases the power losses, while the latter one has a low harmonic, but its sinusoidal voltage transfer ratio (VTR) is 0.812, which decreases load capacity. To improve the loading capacity and decrease the power losses of the five-phase-inverter adjustable speed system, a new space vector over-modulation method based on multi-vector weighting is proposed in this paper, and harmonic characteristics of the proposed over-modulation method are analyzed. The simulation results indicate that the proposed over-modulation method has a lower output voltage error than that with the traditional NFV-SVPWM and has a lower output current THD than that with the traditional NTV-SVPWM. The experimental results verify that the proposed method is correct and feasible.

Enhanced FOPID Controller Based Cascaded Inverter for Grid-Connected Photovoltaic System

An enhanced controller is proposed to investigate grid-connected photovoltaic systems employing cascaded two-level inverters. The primary focus is on optimizing power output, achieved through the development, modeling, and testing of photovoltaic systems using the suggested upgraded controller. This advanced controller, specifically a Fractional Order PID (FOPID) controller, incorporates the Ant-Lion Optimizer (ALO) algorithm for enhanced performance compared to conventional controllers. The FOPID controller’s reliability is emphasized, and further improvements are pursued by optimizing gain parameters through the prescribed method. Power supply under both schemes is examined, and the controller’s performance in extracting maximum power under specified operating conditions is deemed satisfactory. To validate the proposed approach, practical implementation is conducted using the MATLAB/Simulink platform. The effectiveness of proposed and conventional methodologies for analyzing the id and iq currents is assessed. A comparison is drawn between the suggested approach and current methods such as the base controller, GSA, and ABC methodologies. In comparison to the existing methods, the suggested FOPID controller demonstrates superior performance in maintaining the DC link voltage, achieving an efficiency of 94%, while the GSA method reaches 91.5%, the ABC method achieves 91%, and the base controller achieves 90%.

A unified SVPWM fault tolerant control algorithm for single leg fault reconstruction topology of two-level inverter

To improve the reliability of Two-level three phase voltage source inverters, a uniform fault tolerant strategy based on space vector pulse width modulation is proposed for different leg faults. The reconstructed topologies of inverters with different bridge arm faults are different, which makes the basic voltage vector phase of each reconstructed topology inconsistent, resulting in different calculations. Therefore, the coordinate transformation is applied to place the basic voltage vectors of each reconstructed topology on the synchronous stationary αβ coordinate system so that the calculations of the reconstructed topology under different bridge arm faults are unified, thus reducing the complexity of fault-tolerant control. Aiming at the three-phase current asymmetry caused by the neutral point voltage oscillation in inverter topology reconstruction, a transient compensation method of neutral point voltage offset for the α-axis component of the reference voltage vector is introduced to suppress the adverse effects. The compensation method directly offers a neutral point voltage offset value after Clarke transformation and corrects the α-axis component of the reference voltage vector, avoiding the integral calculation in the conventional voltage compensation algorithm. The correctness and effectiveness of the proposed fault-tolerant control strategy are verified experimentally.

TUNING OF PI SPEED CONTROLLER IN DIRECT TORQUE CONTROL OFDUAL STAR INDUCTION MOTOR BASED ON GENETIC ALGORITHMS AND NEURO-FUZZY SCHEMES

Thanks to the positive characteristics of the double stator machine (DSIM), its high reliability, and reduced rotor torque ripples, it has become among the most important multiphase machines included in industrial applications. This article aims to apply the two techniques of artificial intelligence represented by the adaptive neuro-fuzzy inference systems (ANFIS) and the genetic algorithm (GA) for direct torque control (DTC) of the DSIM to improve the performance of the machine. The ability to learn and the parallelism of operation characteristics made exploiting the GA to control the machine possible instead of using the proportional integral controller (PI). Fixed switching frequency obtained, given with the vector selection table and hysteresis, allowed the inclusion of the ANFIS technique in the DTC strategy. Two-level inverters are included to feed the DSIM. Several results prove that the two techniques applied, ANFIS and GA, improve the quality of the electromagnetic torque and flux and the dynamic responses of the DSIM.

PROGRESSIVE STEP MAXIMUM POWER TRACKER FOR CASCADED INVERTER INDUCTION MOTOR DRIVE

This paper presents the idea of an isolated photovoltaic (PV) based cascaded two-level inverter (CTLI), driving squirrel cage induction motor (SCIM). The connected non-linear load approximately represents a centrifugal pump. The control system of this drive is based on a motor control system along with a progressive step perturb and observe (PSPnO) maximum power point tracking (MPPT) technique for the PV sources towards better utilization of the source. This PSPnO MPPT system intends to operate the SCIM so that the energy developed by PV is utilized entirely through variation of the dc-link voltages of the CTLI under both uncertain variances of non-linear load torque and unpredictable solar irradiance. This PSPnO MPPT algorithm has been engaged in the control scheme for generating reference dc-link voltage. This motor control system is designed to operate in a rotor-flux-oriented rotating reference frame. As for generating CTLI’s switching pulses, the space vector pulse width modulation (SVPWM) technique has been used for its good dynamic response. The whole system is designed to be deployable on a low-computation device. The simulations conducted by Simulink and the results are furnished considering various operational conditions.

Open-Circuit Fault Diagnosis of T-Type Three-Level Inverter Based on Knowledge Reduction

Compared with traditional two-level inverters, multilevel inverters have many solid-state switches and complex composition methods. Therefore, diagnosing and treating inverter faults is a prerequisite for the reliable and efficient operation of the inverter. Based on the idea of intelligent complementary fusion, this paper combines the genetic algorithm–binary granulation matrix knowledge-reduction method with the extreme learning machine network to propose a fault-diagnosis method for multi-tube open-circuit faults in T-type three-level inverters. First, the fault characteristics of power devices at different locations of T-type three-level inverters are analyzed, and the inverter output power and its harmonic components are extracted as the basis for power device fault diagnosis. Second, the genetic algorithm–binary granularity matrix knowledge-reduction method is used for optimization to obtain the minimum attribute set required to distinguish the state transitions in various fault cases. Finally, the kernel attribute set is utilized to construct extreme learning machine subclassifiers with corresponding granularity. The experimental results show that the classification accuracy after attribute reduction is higher than that of all subclassifiers under different attribute sets, reflecting the advantages of attribute reduction and the complementarity of different intelligent diagnosis methods, which have stronger fault-diagnosis accuracy and generalization ability compared with the existing methods and provides a new way for hybrid intelligent diagnosis.

High-order sliding mode control with hyperbolic evaluation function for improving performances of a squirrel-cage induction motor fed by a two-level inverter

High-order sliding mode control with hyperbolic evaluation function for improving performances of a squirrel-cage induction motor fed by a two-level inverter