Three-phase Inverter Research Articles

Integrated Magnetic-Based Isolated Three-Phase Inverter With Flux-Rate-Controlled Harmonic Filtering

Integrated Magnetic-Based Isolated Three-Phase Inverter With Flux-Rate-Controlled Harmonic Filtering

Hybrid ADRC and PI Controller Design for Three-Phase Inverter With Nonlinear Loads

Hybrid ADRC and PI Controller Design for Three-Phase Inverter With Nonlinear Loads

An Energy-Feed Type Split-Capacitor Three-Phase Four-Wire Power Electronic Load Compatible with Various Load Demands

Energy-feed power electronic loads can precisely control the phase and magnitude of the power supply output current, achieving the emulation of loads. Moreover, they can feed energy back to the grid for energy regeneration, demonstrating significant research value. This article proposes an energy-fed power electronic load topology and control method that can realize the static and dynamic simulation of linear and non-linear loads and take into account the simulation needs of single-phase, three-phase three-wire, and three-phase four-wire loads. The main circuit uses a two-stage back-to-back AC/DC/AC structure: the front side is a three-phase four-wire split capacitor PWM rectifier bridge, which is used to simulate loads under various operating conditions; the back side is a three-phase three-wire PWM inverter bridge, which realizes the energy feeding back to the grid and reduces the waste of energy; and the intermediate side uses a split capacitor to equalize the voltage and achieve voltage stabilization. The topology is analyzed under the simulation demands of three-phase balanced, three-phase unbalanced, single-phase and non-linear loads. Finally, a MATLAB(R2022a)/Simulink simulation platform is built for a power electronic load with a rated capacity of 200 kVA. The simulation results verify the effectiveness, feasibility, and advancement of the power electronic load proposed in this article.

Design, Modeling, and Validation of Grid-Forming Inverters for Frequency Synchronization and Restoration

This paper focuses on the modeling, analysis, and design of grid-forming (GFM) inverter-based microgrids (MGs). It starts with the development of a mathematical model for three-phase voltage source inverters (VSI). The voltage and current controllers consist of two feedback loops: an outer feedback loop of the capacitance-voltage and an inner feedback loop of the output inductance current. The outer voltage loop is employed to enhance the controller’s response time. The inner current loop is used to provide active damping for the resonance created by the LCL filter. A two-layer control scheme is adopted for the GFM inverter control. The primary decentralized control uses droop control and virtual impedance loops to share active and reactive power. Simultaneously, the centralized secondary control addresses frequency and amplitude deviations induced by the droop control. Additionally, a synchronization loop is proposed for seamless reconnection of GFM inverters to the MG and to connect the GFM-controlled MG to the main grid. It has the advantage that the inverter operates in GFM mode even after the synchronization has occurred. The simulation results have shown that the voltage controller ensures a 0.005 s settling time and maintains the steady-state error at its minimum value of 0.1 V. Similarly, the current controller ensures a 0.006 s settling time with a 10−5 steady-state error. The system with the designed controller has a low total harmonic distortion (THD) of 1.46% and improved power quality of the output voltage. Furthermore, a quick restoration time is observed during load steps and tripping events, with a restoration time of 1 s with 10−10 steady-state error. Synchronization is achieved within 0.8 s for the incoming inverters and requires 3 s to synchronize the MG with the main grid, maintaining a steady-state error of 10−9.

Solar on-grid power plant and its connection to the electric network

The network solar power plant and its connection to the electric network are considered. This system of autonomous alternative power supply belongs to the network type. The main focus of the system is the supply of generated electric power to the consumer's network and the transfer of the surplus to the city network according to the “Green Tariff”. The expected electrical capacity of the solar power plant is 860 kW. The system is a multi-branched star consisting of the following elements: solar batteries; network inverters; systems for monitoring network solar power plant mode parameters; electricity meters; power lines. The necessary number of solar panels to cover the power of consumers has been determined. The distribution of energy generated by solar panels is uniform between phases. Solar panels are placed on special metal ground structures. Inverters are selected to connect the panels to the three-phase alternating current network. Three-phase inverters are installed at this electrical station. The inverter is equipped with additional protective devices to guarantee safe operation in any conditions. Fuses are installed in the inverters to protect the equipment from short circuit and overvoltage. Inverters are installed on metal structures that are placed under tables with solar panels. All direct current wiring is made of specialized solar single-core cable with double polyvinyl chloride non-flammable insulation. The cross-section of the cables is selected according to the permissible current loads and checked for voltage losses. Tiles are laid in metal trays and open on structures. The connection of the solar power plant to the 10 kV network is transferred using a complete transformer substation of the external installation.

Single PCB sensor-based output current reproduction for three-phase inverter systems

This study proposes a practical output current measurement system in a three-phase inverter with a single printed circuit board (PCB) Rogowski coil sensor inserted in the bus between the DC-link capacitor and the power semiconductor module. This system demonstrates its advantage over conventional output current sensors, such as the Hall effect current sensors, in terms of the size, weight, operation temperature and cost. The system can be applied to 6-in-1 power modules as it does not require sensors in the inverter phase legs.In our previous works, we have developed a method called “envelope tracking”, which is used in this system as well. This method traces the switching current instead of the output current to reproduce the output current signal in real-time. Envelope tracking successfully reproduced the output current waveform for single phase inverters under certain conditions. However, a large error is observed in the three-phase inverter demonstration under a high switching frequency (narrow pulse) or when the switching of different phases overlap each other. These errors must be completely suppressed to implement the system for feedback control in three-phase inverters.In this study, a new analog basis output current waveform reproduction system is introduced to suppress the above mentioned errors. This system is implemented in a three-phase insulated-gate bipolar transistor (IGBT) inverter and successfully reproduces the output current with a single PCB sensor inserted between a 6-in-1 IGBT power module and DC-link capacitor, operating under a switching frequency of 3.5–7.0 kHz and output current of 6 A with DC-link voltage of 150 V.

Calculation of Losses in a Motor Fed by a Conventional Inverter and a Battery Distributed Inverter

In the past decade, car manufacturers have started electrifying the traction chain of their vehicles. Although these vehicles attract more and more drivers, most of them have a limited range and are prohibitively expensive. Manufacturers must therefore offer high-performance conversion chains (particularly in terms of efficiency) while controlling costs. The power converter is a particularly crucial element of the conversion chains: it supplies the traction motor, and its structure and the way it is controlled can greatly influence the overall efficiency of the drive train. This paper studies two conversion structures that can be used as vehicle power converters, which are modeled and associated with an electric machine. The first is a classical three-phase inverter, and the second is a breakthrough architecture called IBIS (Intelligent Battery Integrated System). This battery integrates the conversion function directly into the battery, which reduces material costs. Two loss phenomena are also studied and modeled (with the help of finite element methods): iron losses in the electrical machine (magnetic losses in the ferromagnetic material used) and copper losses in the conductors (AC and DC losses in the conductors). The impact of the architecture is evaluated on a set of operating points from a road cycle standardized by the WLTP procedure.

Control and Management Approach of Photovoltaic-Battery-Ultra-Capacitor Energy System in Standalone and Grid-Connected Modes

This paper deals with energy management for the photovoltaic-battery-ultra-capacitor energy system for a standalone and grid-connected. The developed energy system can operate in an isolated or connected mode according to the required power. Indeed, the photovoltaic generator is coupled with the DC bus voltage via a DC–DC power converter, to provide the maximum power from the photovoltaic panels. An energy storage system presented by batteries and ultracapacitors is employed to regulate the DC bus voltage through both DC–DC bidirectional power converters. The DC bus is connected to the AC bus through a three-phase power inverter to control the operating modes and ensure the energy demands. In effect, an energy management algorithm is developed to control the energy flow in the system for a standalone and grid-connected. Hence, the output voltage DC bus is controlled by the energy storage system using a Lyapunov approach to ensure high performance under load and irradiance profile variations. In this context, simulations have been carried out to prove the effectiveness of the proposed photovoltaic system. The developed energy system has been tested in standalone and grid-connected modes with the following scenarios: PV generator supplies the load, PV generator power is limited due to less solar lighting, the electric grid supplies the high load power, the surplus energy of the PV generator is injected into the electric grid, and standalone mode operation.

A Single Stage Photovoltaic Solar Pumping System based on the Three Phase Multilevel Inverter

This paper presents a study of a single-stage DC-AC converter for a solar water pumping application. The topology was based on solar panels connected to a new structure of a three-phase multilevel inverter through DC-bus capacitors. The inverter offers simplicity, requires fewer components compared to conventional ones, and provides optimal voltage and current waveforms with reduced harmonics, eliminating the need for filters. The applied control technique aimed to stabilize the input DC-bus voltage, extract the maximum power using a simple MPPT algorithm, and enhance the efficiency of the water pump through scalar V/f control, regardless of weather changes. A simulation was conducted using the PSIM software, considering a variable daily climate scenario. The results obtained demonstrate the efficiency of the system in extracting energy with optimal torque and current for the pump compared to a classic design based on a three-phase H-bridge inverter.

Power quality disturbance mitigation in grid connected photovoltaic distributed generation with plug-in hybrid electric vehicle

In the last twenty years, electric vehicles have gained significant popularity in domestic transportation. The introduction of fast charging technology forecasts increased the use of plug-in hybrid electric vehicle and electric vehicles (PHEVs). Reduced total harmonic distortion (THD) is essential for a distributed power generation system during the electric vehicle (EV) power penetration. This paper develops a combined controller for synchronizing photovoltaic (PV) to the grid and bidirectional power transfer between EVs and the grid. With grid synchronization of PV power generation, this paper uses two control loops. One controls EV battery charging and the other mitigates power quality disturbances. On the grid connected converter, a multicarrier space vector pulse width modulation approach (12-switch, three-phase inverter) is used to mitigate power quality disturbances. A Simulink model for the PV-EV-grid setup has been developed, for evaluating voltage and current THD percentages under linear and non-linear and PHEV load conditions and finding that the THD values are well within the IEEE 519 standards.

A Health Condition Indicator Localization Method for the Power Devices in Three-Phase Inverter

A Health Condition Indicator Localization Method for the Power Devices in Three-Phase Inverter

Dual-Vector-Based Predictive Torque Control for Fault-Tolerant Inverter-Fed Induction Motor Drives With Adaptive Switching Instant

Four-switch three-phase inverter (FSTPI) is widely applied as a fault-tolerant topology of six-switch three-phase inverter (SSTPI) with an open-phase fault or as a cost-effective topology due to the reduced semiconductor power switches. However, conventional single-vector-based predictive torque control (SV-PTC) for FSTPI-fed induction motor (IM) presents poor steady-state performance and requires high sampling frequency. To address these issues, a dual-vector-based PTC (DV-PTC) for FSTPI-fed IM with adaptive switching instant is proposed in this article. Therein, two optimal voltage vectors are determined in each sampling period, and a simplification strategy for selecting the optimal voltage vectors is established. A switching instant adaptation scheme is developed to improve the steady-state performance of machine control. An optimized overmodulation strategy is proposed to improve the transient-state performance of machine control and reduce the computational burden in digital implementation. Extensive experimental studies validate the effectiveness and superiority of the proposed DV-PTC scheme.

An Efficient Three-Phase Zero-Voltage Switching Passive Resonant Pole Inverter

The brief puts forward a three-phase passive resonant pole inverter with the aim of improving the efficiency by the lower switching loss. The concrete implementation method is that three sets of identical auxiliary circuits, composed of passive devices, are connected respectively in parallel with each bridge arm in order that main switches can implement the function of zero-voltage switching to diminish switching loss by the resonance among passive devices. The higher efficiency can be achieved on condition that the added loss of auxiliary circuits is lower than the diminished switching loss compared with the hard-switching inverter. The brief represents various working state within a switching cycle. The main experimental results are as follows: main switches implement the function of zero-voltage switching in a wide load range and the efficiency value of the presented inverter is equal to 98.5% under the rated condition which is at least 0.5% more than that in other three comparison objects. Thus, the presented inverter has superiority in efficiency over other similar soft-switching inverters.

Three-phase photovoltaic inverter control strategy for low voltage grid current unbalance mitigation

Three-phase photovoltaic inverter control strategy for low voltage grid current unbalance mitigation

A Reconstructed Singular Return Ratio Matrix for Optimizing Design of the PLL in Grid-Connected Inverters

Phase-locked loop (PLL) is essential for the grid-connected inverter to ensure grid synchronization. Since the PLL introduces an negative-resistive admittance to be in parallel with the original inverter output admittance, it poses an instability risk for the grid-connected inverter under weak grid. The system stability can be evaluated by the return ratio matrix, which is the ratio of the inverter output admittance to the grid admittance. Due to the non-singular and non-diagonal properties of this matrix, its eigenvalues are irrational functions, leading to inconvenience of stability analysis and PLL parameters design. To address this issue, this paper reconstructs the return ratio matrix to make it singular. Thus, the eigenvalues become simpler, including a zero eigenvalue and a non-zero eigenvalue. Based on the non-zero eigenvalue, the relation between the gain margin and the PLL parameters is established, and an optimizing design method of the PLL parameters is proposed to achieve system stability and satisfactory PLL dynamic response. Finally, experimental results from a 10-kVA prototype of three-phase grid-connected inverter are provided to verify the validity of the proposed design method.

Thermal Consideration and Design for a 200-kW SiC-Based High-Density Three-Phase Inverter in More Electric Aircraft

Thermal Consideration and Design for a 200-kW SiC-Based High-Density Three-Phase Inverter in More Electric Aircraft

Research on the Application of Motor Field-Oriented Control in Vehicles

The motor application of the FOC strategy of the hybrid system in this text is the battery heat control. The specific contents are as below: SVPWM control. SVPWM is based on the three-phase symmetrical sine wave voltage supply and three-phase symmetrical motor stator ideal flux circle as a reference standard, with different switching modes of three-phase inverter for appropriate switching, to form PWM wave and to form the actual flux vector to track its accurate flux circle. By applying reactive voltage with high-frequency variation and using the FOC control strategy, the inductance characteristic of the motor winding is constantly utilized to generate alternating current on the bus. By taking advantage of the high internal resistance of the cell at low temperatures, the joule heat is constantly generated on the cell. While avoiding the risk of lithium analysis of the cell, heat is generated from the cell itself, and the temperature of the cell is raised. The vehicle results are conducted and show that the battery heat performance is enhanced.

Performance Analysis Of DSMST Converter FED BLDC Motor

A positive output voltage SEPIC-type DC-DC converter called DSMST (modified SEPIC topology) without a transformer for use in electric vehicles. The DSMST converter is derived from the traditional SEPIC converter with the addition of a switching cell. Furthermore, the output diode and inductors are interchanged for the continuous output current. In the realm of electric vehicles, the utilization of Brushless DC (BLDC) motor drives coupled with a DC-DC converter has become increasingly important. Specifically in the context of electric vehicles, the use of BLDC motors offers several technical advantages compared to other types of motors such as DC, induction, and switched reluctance motors. The DSMST converter is connected to the BLDC motor through a three-phase voltage source inverter (VSI) to regulate the voltage and current supplied to the BLDC motor, ensuring optimal performance. To regulate the speed of drive, a closed loop control system is developed using hall sensor signals. The proposed system is developed in the MATLAB/Simulink to check the applicability of electric vehicle configuration and the results shown that the proposed converter is well suitable for electric vehicle applications.

Grid interface control of wind–solar generator in Hail region of Saudi Arabia using FOPI controller

This study investigates the performance of a wind–solar generator (WSG) in the Hail region of Kingdom of Saudi Arabia (KSA) with a fractional order PI controller (FOPI) applied to the grid connection line. The proposed hybrid generator consists of a wind turbine with a PMSM machine and a PV panel connected to a secondary distribution grid by a DC link, three-phase inverter, and an RL filter. The line currents injected into the grid and/or loads are controlled by calculating the output reference voltage of an inverter and by the reference active and reactive requested powers. For this purpose, control loops around the RL filter were developed with fractional-order proportional-integral (FOPI) controllers, and a comparison with classic PI controllers was made. The system was simulated using the MATLAB/Simulink software. The results showed that the generator satisfied the power demand under the climatic conditions of the Hail region. They also demonstrated the good performance of the proposed controllers, which had good tracking accuracy and robustness to variations in wind speed and power demanded by loads in a very short time. The FOPI controller exhibited faster dynamic response and less overshoot than the classic PI controller.

Analysis of the Mechanism and Control of the Unbalanced Operation of Three-Phase Four-Wire Inverters

In this paper, a solution is proposed to the problem of the unequal phase imbalance of output voltage caused by a three-phase, four-wire, split capacitor inverter when the load is unbalanced. First, the triple-loop control strategy was used to solve the unequal amplitude problem. This method used the feedforward + feedback composite control strategy on the inductor current inner-loop and voltage mid-loop to decrease the disturbance of the power and load. And the Root Mean Square (RMS) of voltage on the outer-loop completed the control of amplitude for the three-phase voltage. Second, to solve the imbalanced phase problem, the imbalance operation mechanism of the three-phase four-wire inverter was analyzed. It is known from the analysis that the phase imbalance is related to the DC-side splitting capacitance. The function relations between the DC-side capacitance and phase angle between each phase was simulated by MATLAB. But, it was too complicated to calculate the magnitude of the capacitance value through the functional relationship. In order to simplify the design of the DC-side splitting capacitor, the relations among the imbalanced current, the voltage fluctuations of the DC-side capacitor and the harmonics of load voltage were analyzed. In addition, by following the requirement of the national standard about the harmonics of load voltage, a DC-side capacitor design was mentioned to decrease the influence of imbalanced phase. Finally, simulation and experimental results show that the three-phase load voltage is stable, the THD value is less than 3%, and three-phase voltage unbalance is less than 2%, thus verifying the effectiveness of the proposed DC-side split capacitor design and control strategy.