Level Voltage Source Inverter Research Articles

Dual Motor Power Sharing Control for Electric Vehicles With Battery Power Management

Induction motor powertrains are emerging as a cost-effective option for high-power electric vehicles (EVs). A differential four-wheel drive (D4WD) EV based on two open end winding induction motor (OEWIM) propulsion is presented in this paper. Each OEWIM is driven by two 2-level voltage source inverters (VSI) with two isolated battery packs as the source. The proposed drive control algorithm integrates the uniform state-of-charge (SoC) distribution and fault-tolerant operation. A two-stage look-up table (LUT) based direct torque control (DTC) scheme is proposed to balance the SoC of batteries by selecting the suitable redundant VSI voltage vectors. The proposed LUT-DTC scheme is less sensitive to variations in motor parameters and provides excellent steady-state and transient performance. The results show the superiority of the proposed controller in terms of battery SoC balancing. The performance of the EV drive with the proposed LUT-DTC is validated by both simulation and laboratory experiments for the FTP75 and HFET driving cycles under different operating modes under normal and fault conditions. The dual motor driven D4WD with the proposed LUT-DTC is found to achieve 89.2% efficiency.

Development of Various Types of Independent Phase Based Pulsewidth Modulation Techniques for Three-Phase Voltage Source Inverters

Discontinuous pulse-width-modulation (DPWM) methods have been extensively used in the industrial area to reduce overall losses, which decreases the corresponding thermal stress on the power switches of converters. However, local thermal overload can arise due to different aging conditions of semiconductor devices or failure in the cooling system. This leads to reduced reliability of the converter system due to the low expected lifespan of the most aged switches or phase legs. In this paper, the modified DPWM strategies for independent control of per-phase switching loss are introduced to deal with this matter. The proposed per-phase DPWM techniques are generated by modifying the conventional three-phase DPWM methods for reducing the switching loss in a specific leg, whereas the output performance is not degraded. This paper reports on output performance, including output current total harmonic distortion (THD) and power loss of switching devices, analysis for the various modified DPWM strategies for independent control of per-phase switching loss, which is applicable in 2-level 3-phase voltage source inverters (2L3P VSIs). The results are compared to the corresponding continuous PWM technique to verify and analyze the effectiveness and accuracy of the modified DPWM strategies for independent control of per-phase switching loss.

Hybrid-Clamping SVPWM Scheme for a Four-Level Open-End Winding Induction Motor Drive

An open-end winding arrangement is fed with two typical 2-level voltage source inverters (VSIs) on either side to accomplish multilevel inversion. Two voltage source modules (VSIs) DC-link voltages are kept at a 2:1 ratio to realize the open-end winding induction motor (OEW-IM) power circuit’s four-level configuration. However, the higher DC-link voltage capacitor overcharges its lower DC-link voltage counterpart in the 4-level power circuit configuration. This article proposes a new hybrid-clamping space vector PWM (SVPWM) approach to prevent overcharging. Based on the sample moment, the suggested SVPWM technique clamps one inverter and switches to another inverter. Additionally, it clamps one of the inverter’s switching phases. The proposed PWM method has been found to reduce switching power loss in contrast to earlier SVPWM methods. The proposed SVPWM scheme for the 4-level OEW-IM drive is tested and verified using an experimental laboratory setup.

Electrical Drives Using Model Predictive Controller Strategies

High-level control techniques in power gadgets incorporate Predictive controller of current (PC CONTROL) and Predictive controller of torque (PT CONTROL). It is simple to include system restrictions. There is no need for the weighting component. Together with the PT CONTROL and PC controller systems, the SRM method is the most practicable direct control technique since it doesn't require a modulator and offers 10% to 30% more power than an induction motor. With the same current, an induction motor can only generate between 70 and 90 per cent of the force generated by an SRM due to its lagging power factor. When compared to the PT CONTROL and PC controller method employing an induction motor and a 15-level H-bridge multilevel inverter, the SRM approach reduces THD in torque, speed, and stator current by 23 per cent. The transistors are only swapped when necessary to maintain the limits of flux and torque, which minimizes switching losses. To improve the efficiency of a multilevel inverter, semiconductor switches are switched in a specific pattern. In contrast to the PT CONTROL and PC controller approaches using a 2-level voltage source inverter, the fifteen-level H-bridge multilevel inverter employed in this study, coupled with SRM and IM, gives outstanding torque and flux responses and achieves stable and robust operation. This unique strategy quickly caught the interest of academics due to its simple method.

A Composite Exponential Reaching Law Based SMC with Rotating Sliding Surface Selection Mechanism for Two Level Three Phase VSI in Vehicle to Load Applications

Voltage source inverters (VSIs) are an integral part of electrical vehicles (EVs) to enhance the reliability of the supply power to critical loads in vehicle to load (V2L) applications. The inherent properties of sliding mode control (SMC) makes it one of the best available options to achieve the desired voltage quality under variable load conditions. The intrinsic characteristic of robustness associated with SMC is generally achieved at the cost of unwanted chattering along the sliding surface. To manage this compromise better, optimal selection of sliding surface coefficient is applied with the proposed composite exponential reaching law (C-ERL). The novelty of the proposed C-ERL is associated with the intelligent mix of the exponential, power, and difference functions blended with the rotating sliding surface selection (RSS) technique for three phase two level VSI. Moreover, the proposed reaching law along with the power rate exponential reaching law (PRERL), enhanced exponential reaching law (EERL), and repetitive reaching law (RRL) were implemented on two level three phase VSI under variable load conditions. A comparative analysis strongly advocates the authenticity and effectiveness of the proposed reaching law in achieving a well-regulated output voltage with a high level of robustness, reduced chattering, and low %THD.

Comparative evaluation of different DC-AC converter topologies for cryogenic applications utilizing superconducting materials

Modern transportation applications including electric vehicles (EVs), more electric aircraft (MEA) and electric comprise of different power conversion systems. Reduced weight and improved semiconductor efficiency are the major challenges towards their improved overall performance. To overcome them, cryogenic operation of power electronics converters (CPEC), electric motors, cables, and energy storage components has been under research and evaluation. CPEC are being investigated to drive superconducting machines (SCM) because of their lightweight structure and improved efficiency. CPEC can offer improved switching performance, reduced conduction losses and therefore increased efficiency; because of reduced on-resistance and increased carrier mobility of active devices. This article will discuss how can the benefits of lower operating temperature (< 93 K) be utilized in determining the most suitable DC-AC converter configuration. The paper compares three basic converter topologies: (a) two level voltage source inverter (2L-VSI), (b) three level t-type neutral point clamped inverter (3L-TNPC) and (c) two-level current source inverter (2L-CSI). Analysis is provided based on volume of passive components, electromagnetic interference (EMI) spectra and number of active devices, where all components considered are compatible with low temperatures. It can be observed that utilization of cryogenic temperature affects the volume of passive components, and therefore the overall selection of converter.

Efficient Fixed-Switching Modulated Finite Control Set-Model Predictive Control Based on Artificial Neural Networks

The disadvantage of finite control set-model predictive control (FCS-MPC) is that the switching frequency is variable and relies on the sampling time and operating point. This paper describes how to implement a new algorithm to achieve a fixed-switching frequency functionality for the FCS-MPC. The used approach combines the FCS-MPC with the SVPWM, resulting in the calculation of dwell times and the selection of the best two active vectors for the next sample interval. These dwell times have a significant impact on FCS-MPC performance during transient and steady-state conditions, and their values are determined using various mathematical models. To solve the problem of the fixed-switching frequency with lower harmonics distortion compared to the conventional modulated MPC (M2PC), an ANN-based trained network is proposed to calculate the duty-cycle of the applied vectors and thus the dwell time in the next sampling interval. The ANN network receives the cost functions of the two active vectors and the zero vector from the M2PC control algorithm and determines the optimal duty-cycle for each vector based on a proper tuning. In this way, three goals are achieved, the first goal is that the algorithm explicitly obtains a fixed-switching frequency, and secondly, the cost is as simple as the conventional M2PC. Finally, the feature of including objectives and non-linearity is still applicable. The paper’s case study used the two level voltage source inverter (2L-VSI) for uninterruptible power supply (UPS) applications. The results based on MATLAB/Simulink revealed that the ANN-M2PC has retained all FCS-MPC features in addition to operating at a fixed-switching frequency, while the power quality is significantly enhanced.

Novel multi-device unified powerquality conditioner for powerquality improvement

This paper describes the customizable multi-device unified power-quality conditioner (MD-UPQC) is designed especially for multi-feeder distribution networks. The proposed MD-UPQC can exchange the power between the multi-feeders and proficiently mitigates all voltage-current associated power-quality problems, make sure to maintain balanced power-flow to consumers. At recent days, various manufacturers recommend the provision of multilevel inverters in mid-range customized compensation devices with desirable control schemes. In distinct, the 5-level diode-clamped multi-level inverter (DCMLI) is best suited for MD-UPQC over traditional 3-level voltage source inverter (VSI) topology for attaining enhanced features. In this paper, MD-UPQC has been proposed with three 5-level DCMLI modules interfaced as back-to-back with a common direct current (DC) capacitor. The simplified phase-dispositional modulation technique is easily assembled with proposed universal voltage-current reference controller for significant functioning of DCMLI-MDUPQC device. The operation and performance of proposed model and its control scheme is evaluated with MATLAB/Simulink computational tool, simulation results are presented.

Mitigation of Harmonics Using Novel Sector-Based Switching Pattern Svpwm for a Three-Phase Two Level Voltage Source Inverter

Mitigation of Harmonics Using Novel Sector-Based Switching Pattern Svpwm for a Three-Phase Two Level Voltage Source Inverter

Fixed switching frequency scheme for current predictive control of DFIG

This paper suggests a new current predictive control algorithm for the wind-driven doubly-fed induction generator (DFIG) based on space vector modulation (SVM) with fixed switching frequency. Combining the current predictive controller and SVM has the benefits of a predictive controller, and fixing the switching frequency improves the output waveform quality. However, if classical predictive control is used, the computational burden will still be high. The proposed algorithm uses SVM to fix the switching frequency of the rotor side converter. Additionally, by using an incremental algorithm, the proposed technique prevents examining all inputs over the prediction horizon. As a result, in the proposed current predictive algorithm the computational time is significantly reduced. The detailed state-space model of DFIG and rotor side converter are used to execute the predictive algorithm. The proposed algorithm uses the rotor current to predict the next behavior of the DFIG, and then, by using SVM, the duty cycles of 2-level voltage source inverter are obtained. Finally, the proposed controller's responses are compared to those of the SVM-based field-oriented control strategy. Simulation results of the proposed controller on a two-level voltage source inverter under a balanced three-phase power system illustrate the satisfactory active and reactive power tracking and improved quality of the inverter outputs.

Improved control strategy of dual star permanent magnet synchronous generator based tidal turbine system using sensorless field oriented control and direct power control techniques

ABSTRACT This paper presents a grid-connected tidal stream system with a focus on the reduction of the number of sensors needed by the control scheme. The electromechanical converter is a dual star permanent magnet synchronous generator (DS-PMSG) driven by a horizontal axis marine current turbine (HA-MCT). The generator is controlled via the field-oriented control (FOC) strategy, the speed and the position of the rotor are estimated using an extended Kalman filter (EKF), and the speed is regulated using a fuzzy logic controller. The grid side converter (GSC) consist of a two level voltage source inverter controlled by a virtual flux-based direct power control strategy (VF-DPC), and the current is filtered using an LCL filter. The system is simulated using Matlab/Simulink environment, the simulation results show the efficacy of the proposed control scheme, fuzzy speed regulator, and the EKF estimator, where relative mean error (MRE) of speed tracking is only 0.004, and MRE of estimated speed is as low as 7.3e-6, but a low rotor position estimation error of 1.76 degrees can be observed, however, the high number of pole pairs of the generator amplifies the effect of position error, causing divergences between the controlled dq currents seen by the control scheme and the real dq current that flows in the machine, and a decrease of system effeciency; however, the stability is not affected.

Design space exploration of optimized hybrid SVPWM techniques based on spatial region for three level VSI

The performance of a multilevel inverter depends upon design and selection of an appropriate modulation technique. Space vector pulse width modulation (SVPWM) technique offers more flexibility than other pulse width modulation (PWM) techniques. However, conventional SVPWM technique becomes more complex for multilevel inverter because of increased number of space vectors and redundant switching states. This paper presents a design space exploration method of hybrid SVPWM techniques for three level voltage source inverter (VSI) to reduce total harmonic distortion (THD) and switching loss over wide linear modulation range. A new parameter Harmonic Loss (product of weighted total harmonic distortion factor of the line voltage (Vwthd) and normalized switching loss) is introduced as an objective function, and a spatial region identification algorithm is proposed to determine the optimized switching sequences for hybrid SVPWM technique. Two optimized hybrid SVPWM techniques are proposed based on the optimized switching sequences for three level VSI. The proposed hybrid SVPWM techniques are implemented on a low cost PIC microcontroller (PIC 18F452) and applied on an experimental prototype of three phase three level VSI with an induction motor as load. The experimental results are demonstrated to validate the performance of the proposed hybrid SVPWM techniques.

A four-state CBPWM technique for common-mode voltage reduction in two-level inverter

Common-mode voltage (CMV) leads to a large number of failures in power electronics systems, for example, in two level voltage source inverter (2L VSI)-based circuits. This paper presents a four-state (4S) carrier-based pulse-width modulation (CBPWM) technique which yields the reduced CMV (RCMV) for a 2L VSI. The proposed algorithm is called as 4S RCMV CBPWM. The principle of 4S RCMV CBPWM technique is based on the four-state space vector modulation (4S SVM), which removes the zero vectors in the switching sequence and utilizes the active vectors so that the magnitude of CMV is limited to one-sixth of DC source voltage. In addition, the proposed technique also considers the target of minimizing average CMV values on the whole operation area of the space vector diagram. To implement the proposed algorithm, the CMV function is firstly analyzed so that the requirements for minimized average CMV values are achieved. Control voltages for 2L VSI is deduced from the reference voltages and offset function, thus the required average CMV is achieved. Carrier implementation for proposed algorithm is also analyzed. The theory study is verified by simulation and experiment models the quality of proposed method is evaluated in terms of harmonics distortion factors.

A study on performances of carrier-based pulse-width modulation techniques for three-phase three-level t-type neutral-point-clamped inverter under switch-open-circuit fault on two neutral-point-connected legs

Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI has critical issues in reliability in operation such as switch-open-circuit (SOC) and switch-short-circuit (SSC), which lead to several unrequired issues, for instance, reduction of system performance, distorted and unbalanced output voltages and currents, or triggering the protection circuits. In some applications, the amplitude reduction and harmonics distortion of output voltages in SOC faults are not acceptable. Therefore, it is necessary to develop a pulse-width modulation (PWM) algorithm for 333-type VSI working under SOC fault which guarantees the desired output fundamental component voltage. The simultaneous SOC fault on two neutral-point-connected legs in the 333-type VSI may cause a large reduction in the output voltage. Under this circumstance, the 333-type VSI becomes an asymmetrical one called 322-type VSI. Certain studies regarding to the operation of 333-type VSI under SOC faults have been carried out. However, these studies require more semiconductor devices in order to create a redundant switching circuit. This leads to higher system cost with reduced inverter effieciency due to the additional loss. In this study, two carrier-based pulse-width modulation (CBPWM) techniques, i.e. 322-sinusoidal PWM (322-SPWM) and 322-medium offset CBPWM (322-MOCBPWM) are proposed for 322-type VSI. The proposed techniques are firstly simulated in MATLAB/Simulink and then implemented on a hardware setup. Performances of the proposed techniques are evaluated in terms of total harmonic distortion (THD) and weighted-THD (WTHD) of output voltages. Simulation results show that considering the worst output voltage under SOC fault, vBC, the proposed 322-SPWM technique could improve the THD by 40% and the WTHD by 94% compared with the uncompensated case with m=0.8. The corresponding results of 322-MOCBPWM technique are 42% and 96%, respectively. Characteristics of THD and WTHD values are also presented for demonstration the effectiveness of the proposed algorithm.

ANFIS Based DTC SVPWM Controller for Induction Motor

This paper presents three PWM techniques, space vector PWM (SVPWM). SVPWM gives the more rms stator flux ripples in induction motor at 0.76 modulation indices, which gives more ripples in current and torque distortion. The flux performance of the induction motor is improved using three PWM (TPWM) due to twin switching transition with less area of rms stator flux ripple. The PI-control (PIC) doesn’t give the good dynamic performance of the induction motor drive using two level Voltage Source Inverter due to sudden changes in the load or speed. Further to improve dynamic performance in the torque and Flux of induction motor drive is simulated using type-2 fuzzy logic control (TP2FLC) and ANN in place of PIC because; TP2FLC and ANN is effectively dealing with uncertainties, and simulation results of speed, torque, flux and stator current of induction motor is compare with PIC of SVPWM and TPWM.

Enhanced Voltage Switching States for Direct Torque Controlled Open End Winding Permanent Magnet Synchronous Motor Drive

Direct torque control (DTC) is most popular technique used in industries for adjustable speed of drives. It has simple control algorithm without any pulse width modulation technique and vector transformations involvement. Two level voltage source inverter (VSI)-fed permanent magnet synchronous motor (PMSM) operated with DTC has higher torque and flux ripple problems due to the limited voltage vectors availability, which affects the performance of drive. To alleviate these problems, more number of voltage space vectors should be available for DTC of PMSM drive. In this article, DTC for open-end winding PMSM drive (OEW-PMSM) is proposed. A two level dual VSI-fed OEW-PMSM drive configuration attains three level inversion with an equal dc link voltage to VSIs. Similarly four level inversion can also be attained with an unequal dc link voltage of 2:1 ratio given to dual VSIs. Therefore availability voltage space vectors are increased for PMSM drive operation. The effective voltage switching tables for DTC operated OEW-PMSM drive at different speed conditions are proposed to make its performance more satisfactory, thus achieving less torque and flux ripples and also reduced common mode voltage (CMV). To validate this, Simulink/MATLAB and real time experimentation are performed on 3.7 kW PMSM drive.

An efficient hybrid digital architecture for space vector PWM method for multilevel VSI

This paper presents an efficient, cost effective design implementation of a hybrid digital architecture for space vector pulse width modulation (SVPWM) method for multilevel inverters (MLIs). The SVPWM method is one of the most popular real time PWM method for three phase voltage source inverter (VSI). The implementation of SVPWM method becomes complex with an increase in the number of levels in a multilevel inverter. The SVPWM method for multilevel inverter is a multitask system. The main constraint when it comes to implementing SVPWM for multilevel inverters is the processing of dwell time computation and the generation of PWM gate signals for all of the switches with an accurate delay. A hybrid hardware structure consisting of a simple low-cost, low-power dsPIC micro controller (dsPIC 30F4011) and a state of the art Field Programmable Gate Array (FPGA) (Cyclone V 5CGXFC5C6F27C7N) is used to implement SVPWM. The proposed hybrid digital architecture utilizes the advantages and resources of the dsPIC and FPGA. The hybrid digital architecture meets the timing constraints of multitasking through synchronization and parallelism. A communication interface between the dsPIC and the FPGA reduces the design complexity. The software overhead for the communication interface remains fixed for any number of levels. The hybrid structure of the digital architecture provides scalability for the SVPWM method with more number of levels in multilevel inverter. The operation of the proposed hybrid digital architecture is experimentally validated with an optimized SVPWM method for a five level VSI. An optimized region identification algorithm and simple dwell time expressions are described for a five level SVPWM. The input DC of the five level VSI is obtained from a differential power processing (DPP) based PV system. Experimental results under different operating conditions are presented.

Performance analysis of SPRS-based induction motor drive using multi-level inverter and buck-boost chopper

This paper presents the performance analysis of 'induction motor drive' (IMD) utilising slip power recovery scheme (SPRS) with two and three level voltage source inverter (VSI) and buck-boost chopper employing gate turned off thyristor, metal-oxide semiconductor field effect transistor, insulated gate bipolar transistor as switching devices. A mathematical model of 2 hp, 400 V, 50 Hz, 1,440 rpm IMD has been developed and simulated in MATLAB. The performance parameters taken for induction motor drive are reactive power, power factor, efficiency, and total harmonic distortion (THD) of the supply. The novelty of proposed scheme lies in the implementation of simulation model of SPRS using three level inverter and buck-boost chopper from the dynamic model library of MATLAB/Simulink. The simulation results have shown that two-level VSI with chopper controller has enhanced the power factor and efficiency of IMD compared to the SPRS without chopper. The three-level inverter has reduced the reactive power consumption and THD, consequently, enhanced the quality of power supply.

Hybrid single and double‐voltage vector‐based model predictive common‐mode voltage reduction method for 2‐level voltage source inverters

To reduce the common-mode voltage (CMV) as well as the current total harmonic distortions (THDs) of 2-level voltage source inverters (2L-VSIs), a hybrid single and double-voltage vector (VV)-based model predictive control (MPC) method is proposed. Firstly, a two non-zero VV-based MPC strategy is proposed to reduce the CMV as well as the current THDs. Secondly, the influences of the dead time on this method are analysed in detail, and an improved VV preselection method is further proposed to remove the dead time effects. Thirdly, considering the impacts of the control delay and the current ripples, a new current sector division method is presented, based on which a hybrid single and double-VV-based MPC strategy is finally proposed. Furthermore, the current variation per control period under the action of different VVs is also analysed in-depth in this study to lay a solid theoretical foundation for dividing the current sector more properly. Both the simulation and experimental studies are carried out to verify the effectiveness of the proposed method.

Новая централизованная топология фотоэлектрических преобразователей, работающих с сетью, оптимизированная для условий частичного затенения

Grid-connected centralized inverters based on traditional topologies are one of the best solutions for medium and large-scale photovoltaic (PV) power plants due to their low cost and simplicity. However, the output power of these conventional topologies is drastically decreased because of partial shading effects or mismatch between PV panels. This paper proposes a new grid-connected centralized inverter topology based on a novel photovoltaic current collector optimizer (CCO) to enhance the power yield from PV array in case of partial shading or PV modules mismatch. The PV modules are stacked by CCOs and then interfaced to the grid through three phase-two level voltage source inverter (VSI). The CCOs are used to improve the power harvest from PV array instead of using bypass and blocking diodes which deforms the PV array characteristics and reduces its output power. The VSI is used to inject a high-quality AC current into the grid and perform maximum power point tracking (MPPT) together. Computer simulation is carried out using MATLAB/Simulink in order to test operation of the proposed topology. Simulation results show that the proposed topology offers an excellent steady-state response, fast dynamic response, perfect and robust tracking of maximum power point during partial shading condition.