Three-phase Voltage Source Inverter Research Articles

Reactive Power Based MRAS for Speed Estimation of Solar Fed Induction Motor With Improved Feedback Linearization for Water Pumping

This article presents an efficient method for control of a solar water pumping system consisting of an induction motor drive (IMD) with a model reference adaptive system (MRAS) based adaptive mechanism of speed estimation. An improved perturb and observe control technique is implemented to achieve maximum power point tracking. The gating signals are produced by utilizing a space vector pulsewidth modulation scheme for a three-phase inverter. An improved third order integrator (ITOI) is proposed for adaptation of flux for improvement in the performance of the drive. The MRAS is used for estimation of slip speed and synchronous speed two estimated speed signals are used to generate the motor speed. The proposed control methodology with the MRAS-based reactive power technique for the estimation of speed has improved the system stability for a wide range of drive speed. This system with a single-stage photovoltaic (PV) topology and switching logic obtained from space vector modulation operating three-phase voltage source inverter fed IMD with a pump as a load is designed and implemented in MATLAB/Simulink. The suitability of the developed system is validated through experimentation in the laboratory.

A Simulink / MATLAB Model of a Three-Phase Sinusoidal PWM Inverter Driven Induction Motor

A three-phase voltage source inverter driven induction motor dynamic model developed using Simulink / MATLAB is presented. The presented model is derived from the d-q motor model. A modular approach is used in the construction of the motor-drive system model. The model presented is useful for studying both the steady-state and transient behavior of the motor drive system. The developed model enables the user to access all parameters of interest. Modifications can be made to the system model in order for it to be used with other motor drive system topologies. The model has benefits for use by undergraduate student researchers, and professors when used as a teaching tool in undergraduate courses.

Implementation of 3L DPWM Techniques for Parallel Interleaved 2L VSIs

Parallel interleaved two-level (2L) three-phase voltage source inverters (VSIs) are widely used due to their distinct advantages of high power delivery, modularity, low current rating devices, etc. Along with these advantages, the parallel interleaved 2L VSIs could also be analyzed as a single three-level (3L) VSI. Conventionally parallel interleaved 2L VSIs are modulated using the 2L pulsewidth modulation (PWM) techniques. However, implementation of parallel interleaved 2L VSIs using the 2L PWM techniques may generate a higher ac side current ripple as compared to implementing the parallel interleaved 2L VSIs using 3L PWM techniques. This paper proposes a carrier-based method for implementing different 3L discontinuous PWM (DPWM) techniques for parallel interleaved 2L three-phase VSIs. Comparison of different 2L switching sequences for implementing a 3L DPWM switching sequence based on circulating current, line current ripple, and switching loss is also carried out. Simulation and experimental results are also displayed to validate the proposal.

Control of Hybrid Wind–Diesel Standalone Microgrid for Water Treatment System Application

This article deals with the control of a standalone microgrid based on variable speed wind turbine (WT) and fixed speed diesel generator (DG) for water treatment application. A perturb and observe (P&O) method is used to achieve the maximum power point tracking (MPPT) from the WT without using speed sensors. Two levels of control are proposed for the three-phase voltage source inverter for voltage and frequency regulation at the point of common coupling (PCC) and power management in standalone and diesel connected modes. Furthermore, the battery energy storage is controlled using simple approach to balance the power in the system during load variations and wind speed changes. The performance of the proposed system is tested using MATLAB/Simulink under load and weather variations. In addition, the system is tested on a small-scale prototype in the laboratory under load and wind speed variations.

Control of Dual Three-Phase Permanent Magnet Synchronous Machine Based on Five-Leg Inverter

This paper proposes a current control of dual three-phase permanent magnet synchronous machine (PMSM) based on five-leg inverter. The five-leg inverter can be utilized to drive dual three-phase PMSM with full torque at slow speed when the conventional dual three-phase voltage source inverter (VSI) has a faulty inverter leg. Usually, the common leg in the five-leg inverter may have severe current stress. By dedicated selection of which two phases as a pair to share the common leg, its current rating is approximately half of current rating of other legs. Meanwhile, the five-leg inverter can fully fulfill the vector space decomposition control for dual three-phase PMSM, which has the same dynamical performance as the conventional dual three-phase VSI. However, due to the asymmetry of five-leg inverter non-linearity, the currents of dual three-phase PMSM are unbalanced. To mitigate this issue, the five-leg inverter non-linearity compensation is also introduced and investigated in this paper, whose effectiveness is verified by comparative experiments on a prototype dual three-phase PMSM.

Design and Development of Three-Phase Voltage Source Inverter for Variable Frequency Drive

Three phase induction motors are the workhorse of industry. Variable speed operation of the motor enables substantial energy savings through implementation of variable frequency drives. This project concerns on the design and implementation of three-phase voltage source inverter (VSI) for variable frequency drive. The focus was to generate variable frequency output suitable to be fed to the induction motor for the purpose of variable speed control. SPWM signal was generated through SIMULINK algorithm. The VSI circuit was designed, fed with SPWM trigger signal and simulated for variable frequency output in terms of line-to-neutral and line-to-line voltage across R-L load. In the experimental setup, the real VSI system was developed, the SPWM trigger signal generated through SIMULINK and interfaced to hardware using Arduino microcontroller. The output is dropped across resistive load and parameters line-to-neutral and line-to-line voltage was measured. Three set of output voltage with frequency of generated at 20Hz, 50Hz and 70Hz. Thus, experimental result validated that variation of frequency of voltage output of the VSI has been successfully achieved.

Variable switching frequency hybrid PWM technique for switching loss reduction in a three-phase two-level voltage source inverter

Power loss reduction is one of the main objectives in power electronic system design for achieving higher efficiencies and enhancing system reliability. In this regard, this paper aims to develop a variable switching frequency hybrid pulse width modulation (VSF-HPWM) method to maximize loss saving while maintaining the same current total harmonic distortion (THD) of the conventional scheme. In doing so, this technique utilizes the modulation signal and the switching frequency simultaneously. Using a predefined mathematical representation of current ripple in every switching cycle, the modulating signal (either discontinuous or conventional space vector modulation) with lower RMS current ripple is applied. Meanwhile, the number of commutations under the constrains of constant RMS ripple is reduced by varying the switching frequency. The performance analysis is validated through MATLAB Simulink which shows that the proposed strategy can save up to 53% of switching losses with a similar THD of the conventional scheme.

Simplified double switching SVPWM implementation for three‐level VSI

A generalised space vector pulse width modulation (SVPWM) framework for the realisation of all double switching states with a memory-optimised method is proposed to reduce the total harmonic distortion (THD) and to provide neutral point voltage balancing for three-level NPC voltage source inverter (VSI). The proposal provides an efficient SVPWM implementationwith reduced hardware requirement and zero increase in software complexity in comparison to the existing schemes. Microcontroller analogue-to-digital converter (ADC) hardware replaces multichannel ADC and associated Field programmable gate array hardware in this proposal. The proposed method follows digital control architecture and eliminates the need to sample phase voltages separately. The proposed algorithm samples rms voltage of one phase and generates eight bit modulation index command by a suitable compensation algorithm. The implemented SVPWM algorithm takes the modulation index command value and generates phase voltage values by multiplying with the stored sine angle values. Gate pulses are generated in the proposed implementation by the hardware pulse width modulation (PWM) block and there is no need for digital-to-analogue converter. The proposed strategy is validated with a fundamental frequency of 50 Hz on a 2 KVA three-phase three-level insulated gate bipolar transistor-based VSI using low-cost PIC microcontroller. The superiority of the proposed method lies in providing an efficient three-level SVPWM implementation with reduced THD, neutral point voltage balancing, reduced hardware requirement, small lookup table and zero increase in the software computing overhead.

A STATCOM Based on a Three-Phase, Triple Inverter Modular Topology for Multilevel Operation

In this paper, a static synchronous compensator (STATCOM) is proposed in which a new modular structure with conventional three-phase voltage source inverters is used to multilevel operation. The inverters are connected to a transformer in an open-end winding configuration and with three independent DC links. In this structure, the inverters will be connected in a cascade configuration. Besides the multilevel operation, the system is also characterized by low required blocking voltages for switch ratings, since the proposed STATCOM can apply the double of the DC capacitor voltage to the transformer windings. The development of the control system for the proposed topology is also presented. The operation of the proposed topology and the performance of the developed control system will be tested through several simulation and experimental tests.

A Novel Scalar PWM Method to Reduce Leakage Current in Three-Phase Two-Level Transformerless Grid-Connected VSIs

The advancement in modulation strategies brings emergent solutions to suppress the leakage current in three-phase two-level transformerless grid-connected voltage source inverters (VSIs). However, most of the techniques are analyzed based on reduced common-mode voltage pulsewidth modulation (PWM) in motor drivers but fail to satisfy the specific requirement of grid-connected applications, such as wider power factor operation and lesser current distortion. To overcome such substantial drawbacks, this paper proposes a novel scalar PWM method for transformerless grid-connected VSIs. First, presented through a generalized scalar approach with unified zero-sequence voltage generation, the method is simple to implement and favored in practice. Besides, systematic and comprehensive mathematical analysis is illustrated to exhibit the validity of implemented method in reducing leakage current and shows its advantages over whole power factor range in terms of dc-link current harmonic, output current quality, and switching losses. Finally, simulations and experimental results are carried out to verify the effectiveness and superiority of the proposed method.

A Control Strategy for a Three-Phase Grid Connected PV System under Grid Faults

This paper proposes a Low-Voltage Ride-Through control strategy for a three-phase grid-connected photovoltaic (PV) system. At two stages, the topology is considered for the grid-tied system fed by a photovoltaic generator with a boost converter followed by a three-phase voltage source inverter. A flexible control strategy is built for the proposed system. It accomplishes the PV converter operations under the normal operating mode and under grid faults (symmetrical and asymmetrical grid voltage sag). The boost converter is controlled via an incremental conductance maximum power point tracking technique to maximize the PV generator power extraction. In the case of voltage sag, the implemented control strategy provides a switch between MPPT mode and non-MPPT mode to ensure the protection of the power converters. Theoretical modeling and simulation studies were performed, and significant results are extracted and presented to prove the effectiveness of the proposed control algorithm.

Vector Current Control Derived from Direct Power Control for Grid-Connected Inverters

We propose a vector current control derived from direct power control (VCC-DPC) for a three-phase voltage source inverter (VSI) in the synchronous rotating frame through instantaneous real and reactive powers. The proposed VCC-DPC method has the same control structure as the conventional VCC except for the coordinate transformation, since we obtain the $d$ – $q$ axes currents model of VSI without using Park transformation and the phase-locked loop (PLL) system. Consequently, the proposed method has the same property as the conventional VCC if the PLL extracts the phase angle of the grid voltage correctly. However, with the consideration of the slow dynamics of the PLL, the proposed method has an enhanced dynamical performance feature compared with the conventional VCC. Moreover, it has another benefit that the reduction of the computational burden could be expected since there is no Park transformation and the PLL in the controller implementation. We can guarantee that the closed-loop system with the proposed method is exponentially stable in the operating range. Finally, both simulation and experimental results using a 15-kW-inverter system match the theoretical expectations closely.

A Comprehensive Double-Vector Approach to Alleviate Common-Mode Voltage in Three-Phase Voltage-Source Inverters with a Predictive Control Algorithm

In this paper, a comprehensive double-vector approach is proposed to alleviate the common-mode voltage of voltage-source inverters based on a model predictive control scheme. Only six active vectors are selected to alleviate the common-mode voltage. Furthermore, one sampling period must be split to apply two non-zero vectors, which can generate currents with small current ripples and errors, despite not using zero vectors. The developed algorithm regards in full all 36 possible cases combined by two non-zero active vectors when selecting two vectors and splitting them into one sampling period. Thus, an optimal future set of two non-zero active vectors and optimal durations of two non-zero active vectors to produce the smallest current errors between the real currents and the reference in future load current trajectories were selected from 36 entire sets. This was done to minimize the cost function defined at the time when it varies from the first vector to the second vector and at the next sampling instant. Thus, the proposed algorithm can control the output currents with a fast transient response and reduce output-current ripples and errors, as well as alleviate the common-mode voltage to ± V d c / 6 .

Design, Analysis, and Discussion of Short Circuit and Overload Gate-Driver Dual-Protection Scheme for 1.2-kV, 400-A SiC MOSFET Modules

This paper proposes short circuit and overload gate-driver dual-protection scheme based on the parasitic inductance between the Kelvin- and power-source terminals of high-current SiC mosfet modules. The paper presents a comprehensive analysis of the two schemes in question, including worst-case analysis used to assess their parametric dependence due to manufacturing tolerances and temperature variations, as well as the in-depth design procedure that can be generally applied to any power module containing a Kelvin-source. For verification, a compact 1.2-kV, 400-A half-bridge module integrating the two protection circuits was developed. The results obtained demonstrate a response time within tens of nanoseconds, and effectively validate their functionality under short circuit and overload scenarios. Finally, a 100-kW, 400-V dc three-phase voltage-source inverter was used to demonstrate the gate-driver with integrated protection functions under 105°C ambient temperature conditions.

Optimal Tracking With Disturbance Rejection of Voltage Source Inverters

This paper presents a novel voltage regulator design methodology for a three-phase voltage source inverter with uncertain load dynamics. Different from existing literature, the load is treated as a dynamic uncertainty and a robust optimal state-feedback controller is proposed through the integration of optimal output regulation theory and backstepping method. To avoid sensing the inductor current, an output-feedback control scheme is developed as well. Stability of the inverter–load system is rigorously analyzed via the small-gain techniques. It is ensured that the tracking error asymptotically converges to zero through both the proposed state-feedback and output-feedback controllers. A standard proportional resonant controller is also designed for the purpose of comparison. It is shown that the proposed controller has inherent robustness and does not require retuning with different applications. The controller design method is generalized for grid-tie applications, since the grid can be regarded as a stable load system. Simulations and experimental results show the effectiveness of the control approaches.

Application of fractional-order voltage controller in building-integrated photovoltaic and wind turbine system

The share of electricity generation based on clean, inexhaustible and continuous energy sources, such as solar and wind, in total energy production, is rising day by day due to its significant advantages such as having the less negative impact on global climate and environmental pollution and not requiring fuel for energy production. It is reported that commercial and residential buildings correspond to about 20.1% of the world energy consumption, so it is necessary to provide energy needs of buildings with hybrid renewable energy systems. When using non-continuous energy sources such as solar panel and wind turbines, it is important to ensure ensuring a stable and quality power flow to the building while the power demands of building show very sharp variability. This work presents a voltage control system using fractional-order operators in the smart residential building-integrated hybrid renewable power plant (solar + wind). In this research article, fractional-order proportional–integral/proportional–integral–derivative controllers are proposed on a synchronous frame for a pulse-width modulation based three-phase voltage source inverter in residential building-integrated solar panel and wind turbines system (building-integrated photovoltaic/wind turbine system) in order to improve the quality of injected voltage to building. When comparing the effect of closed-loop voltage control system with integer order controllers (proportional–integral and proportional–integral–derivative) on the power quality at the building distribution by analyzing the simulation results for proposed case study, use of fractional-order voltage controllers for nonlinear system such as building integrated with hybrid renewable sources is more suitable than using integer order voltage controllers.

Performance-Based Design of Induction Motor Drive for Single-Stage PV Array Fed Water Pumping

This paper presents an improved designed induction motor, used for photovoltaic (PV) array fed water pumping system by modifying the rotor and stator slots. The overall system is designed without a mechanical sensor to reduce both cost and complexity with the simultaneous assurance of optimum power utilization of a PV array. The proposed system consists of an induction motor operated water pump, controlled by field-oriented control with artificial neural network current control technique. The maximum power point tracking as well as dc-link voltage, is regulated by three-phase voltage source inverter. The estimation of motor speed eliminates the use of a mechanical sensor and makes the system cheaper and robust. A new robust speed adaptive algorithm is presented, which is less dependent on parameters. A detailed study of various factors affecting the efficiency of the motor is given to improve the behavior of the induction motor drive for water pumping. The designed motor is tested on a developed prototype in the laboratory and its suitability is judged through various tests under steady-state and dynamic conditions of insolation variations.

An SiC MOSFET Based Three-Phase ZVS Inverter Employing Variable Switching Frequency Space Vector PWM Control

In this paper, a variable switching frequency space vector pulsewidth modulation control is proposed. It is used to achieve zero voltage switching (ZVS) for a three-phase grid-connected voltage source inverter with unity power factor. A wide range of ZVS can be realized without any additional sensors, auxiliary circuits, or current zero crossing detection circuits. The switching frequency can be easily calculated by a digital controller. The frequency variation range in a line cycle is only about 1.5 times at any specific load. An LCL filter is used to attenuate the high current ripples at the inverter side, and active damping is adopted to avoid the resonance and reduce the filter power loss. The switching loss can be significantly reduced by using silicon carbide mosfet s so that the conversion efficiency is high. The power density can also be improved due to the high switching frequency and the low inductance value of the filter. The operating principle, design considerations, and loss analyses are discussed in detail. A 3.5-kW simulation and experimental prototype interfacing a 350–400-V dc with a three-phase 110-V ac grid is developed to verify the performance of the proposed control strategy.

Model Predictive Current Control Method with Improved Performances for Three-Phase Voltage Source Inverters

In this paper, the model predictive current control (MPCC) method using two vectors has been proposed to control output currents of three-phase voltage source inverters (VSIs) with small current errors and current ripples. Also, the proposed method can reduce switching losses by applying the vector pre-selection technique to the MPCC for the VSI. The VSI generates seven voltage vectors to control the output currents, but the proposed method uses four available voltage vectors with one switch, which are classified by the vector pre-selection method clamping one leg and conducting the largest output current among the three legs to reduce the switching losses. In the proposed method, selecting two future voltage vectors among the four voltage vectors and dividing them in a future sampling period are determined by an optimization process. The proposed method results in the lower total loss, better total harmonic distortion (THD), and smaller current errors than the conventional method with half the sampling period of the proposed method due to the optimal process. Simulation and experimental results of the three-phase VSIs are presented in order to verify the effectiveness of the proposed method.

A Generalized Method to Generate Carrier-Based 3L PWM Techniques Using Two Parallel Interleaved 2L VSIs

Two parallel interleaved two-level (2L) three-phase voltage source inverters (VSIs) can be analyzed as a single three-level (3L) VSI. A generalized carrier-based method is proposed in this paper for implementing different 3L pulsewidth modulation (PWM) techniques using two parallel interleaved 2L VSIs. The proposed method modifies the given three-phase reference signals of 3L VSI for implementation of the PWM technique using two parallel interleaved 2L VSIs. The influence of nonidealities on the equivalent 3L PWM switching sequences is also discussed. To overcome the effect of nonidealities, a new modified discontinuous PWM technique (MDPWM1) is proposed. The analysis of different performance indices is carried out for different 3L PWM techniques, and the key advantages of different PWM techniques are identified. Simulation and experimental results are also presented.