Two-level Three-phase Voltage Source Inverter Research Articles

Mathematical Modeling of Device Currents in Space-Vector Modulated Two-Level Three-Phase Voltage Source Inverter

Mathematical Modeling of Device Currents in Space-Vector Modulated Two-Level Three-Phase Voltage Source Inverter

A Low Common-Mode SVPWM for Two-Level Three-Phase Voltage Source Inverters

In order to reduce the common-mode voltage (CMV) generated by the use of space vector pulse width modulation (SVPWM) in two-level three-phase voltage source inverters, a low common-mode SVPWM method is proposed. In this method, the voltage plane is divided into 12 sectors, and on each sector, two non-zero vectors of the same class and one single zero vector are adopted for synthesis. The action time of the zero vector is placed at both ends of each switching cycle, the currents are sampled at the beginning of each switching cycle, and the action time and sequence of vectors on each sector is provided. Simulation and experimental results show that, in the vector control system of a permanent magnet synchronous motor fed by the inverter, compared with the conventional SVPWM, the proposed method reduces the CMV peak-to-valley value by 33.333%, the CMV jump frequency by three times, and the performance of the line voltage and line current. The electromagnetic torque and rotor speed remain good, which has good application value in high-performance drives.

Gamma Modulation Based Three-Phase Two-Level Voltage Source Inverter For Reduced Switching Losses With Dynamic Load Changes

Gamma Modulation Based Three-Phase Two-Level Voltage Source Inverter For Reduced Switching Losses With Dynamic Load Changes

Comparisons of Loss Reduction Techniques Based on Pulsewidth Modulation and Model Predictive Control for Three-Phase Voltage Source Inverters

Due to the lack of comparative studies between discontinuous pulse-width modulation and model predictive control methods for reducing switching losses in two-level three-phase voltage source inverter, a comparative analysis of a generalized discontinuous pulse-width modulation and two model predictive control approaches for reducing switching losses is studied in this paper. Both generalized discontinuous pulse-width modulation and two model predictive control approaches are described and conducted in the simulation and experiment. The output performance is obtained by these methods after conducting in various conditions, including switching frequency, output power, and load conditions. It is validated that the generalized discontinuous pulse-width modulation control scheme achieves a better control performance at steady-state, while two model predictive control schemes have better transient-state performance with a superior dynamic. Additionally, the generalized discontinuous pulse-width modulation approach achieves better reducing switching losses performance and has slightly higher efficiency than that of two model predictive control approaches.

Theoretical and Experimental Comparative Analysis of Finite Control Set Model Predictive Control Strategies

This research paper studies and highlights the features of the most popular finite control set model predictive control (FCS-MPC) strategies available in the state of the art, which are the optimal switching vector (OSV-MPC), modulated model predictive control (M2PC), and optimal switching sequence (OSS-MPC) methods. Thus, these strategies are studied experimentally by analyzing the transient and steady state performance using a grid tie conventional three-phase two-level voltage source inverter (VSI) with inductive output filter in a Typhoon HIL real-time simulator (RTS) with a Texas Instruments F28379D digital signal processor (DSP). Hence, quantitative indicators, such as the maximum tracking error, the mean absolute error, the settling time, the total harmonic distortion, the switching frequency spectrum, the switching pattern, and the computational burden are compared with the aim to deduce the best strategy for each criteria.

Fault diagnosis of wind turbine power converter using intrinsic mode functions with relative energy entropy

PurposeThe purpose of this paper is to prevent the destruction of other parts of a wind energy conversion system because of faults, the diagnosis of insulated-gate bipolar transistor (IGBT) faults has become an essential topic of study. Demand for sustainable energy sources has been prompted by rising environmental pollution and energy requirements. Renewable energy has been identified as a viable substitute for conventional fossil fuel energy generation. Because of its rapid installation time and adaptable expenditure for construction scale, wind energy has emerged as a great energy resource. Power converter failure is particularly significant for the reliable operation of wind power conversion systems because it not only has a high yearly fault rate but also a prolonged downtime. The power converters will continue to operate even after the failure, especially the open-circuit fault, endangering their other parts and impairing their functionality.Design/methodology/approachThe most widely used signal processing methods for locating open-switch faults in power devices are the short-time Fourier transform and wavelet transform (WT) – based on time–frequency analysis. To increase their effectiveness, these methods necessitate the intensive use of computational resources. This study suggests a fault detection technique using empirical mode decomposition (EMD) that examines the phase currents from a power inverter. Furthermore, the intrinsic mode function’s relative energy entropy (REE) and simple logical operations are used to locate IGBT open switch failures.FindingsThe presented scheme successfully locates and detects 21 various classes of IGBT faults that could arise in a two-level three-phase voltage source inverter (VSI). To verify the efficacy of the proposed fault diagnosis (FD) scheme, the test is performed under various operating conditions of the power converter and induction motor load. The proposed method outperforms existing FD schemes in the literature in terms of fault coverage and robustness.Originality/valueThis study introduces an EMD–IMF–REE-based FD method for VSIs in wind turbine systems, which enhances the effectiveness and robustness of the FD method.

A Predictive Current Control Strategy for a Medium-Voltage Open-End Winding Machine Drive

This paper presents a medium-voltage drive based on an open-end winding induction machine supplied by a multilevel power converter topology. The power converter consists of cascaded two-level three-phase voltage source inverters (VSI) connected to each side of the machine windings and each VSI is fed by an isolated DC supply. The topology has been previously reported in the literature as a sinusoidal pulse-width modulation operating in an open loop. In this work, a closed-loop model predictive control (MPC) strategy is proposed. MPC offers a much simpler method to control the power switches of the inverter compared to complex modulation strategies that are typically used in multilevel converters. Moreover, the advantage of reducing the common-mode voltage offered by the open-end winding configuration is fully exploited in this work. Simulation results are presented to validate the performance of the proposed topology and control method.

Fixed-Switching-Frequency Modulated Model Predictive Control for Islanded AC Microgrid Applications

In this paper, a fixed-switching-frequency modulated model predictive control (M2PC) is established for a two-level three-phase voltage source inverter (VSI) working in an islanded AC microgrid. These small-scale power systems are composed by two or more VSIs which interface DGs, controlling the voltage amplitude and frequency in the system, and simultaneously sharing the load active and reactive power. Generally, these operational characteristics are achieved using hierarchical linear control loops, but with challenging limitations such as slow transient reaction to disturbances and high proneness to be affected by parameter modifications. Model predictive control may solve these issues. Nevertheless, the most used and developed predictive control scheme, the finite-set model predictive control (FS-MPC), presents the drawback of having the harmonic spectrum spread over all the frequencies. This brings issues with coupling between the different hierarchical control levels of the whole microgrid system, and eventually, when designing the filters for main-grid connection. This paper aims to solve these issues by developing the fixed-switching-frequency M2PC working with higher-level control loops for operation in an islanded AC microgrid. These advantages are proved in an AC microgrid configuration where methodology for paralleling multiple M2PC-regulated VSIs is described, with rapid transient response, inherent stability, and fully decentralised operation of individual VSIs, achieving proper load power sharing, eliminating circular currents, and proper waveforms for output currents and capacitor voltages. All these achievements have been confirmed via simulation and experimental verification.

Selection of PWM Methods for Common-Mode Voltage and DC-Link Capacitor Current Reduction of Three-Phase VSI

This paper evaluates several important pulse-width modulation (PWM) methods developed to reduce the common-mode voltage (CMV) or DC-link capacitor current (DCC) of two-level three-phase voltage source inverter (VSI) in motor drive applications. In addition, a PWM selection criterion is introduced to properly utilize these advanced PWM methods in the VSI system. In the motor drive systems, the high CMV generates the large common-mode current, which may cause electromagnetic emissions and motor damages. Also, the large DCC may have an adverse effect on the life expectancy and increase the volume of DC-link capacitor. Therefore, reducing the CMV and DCC is required in modern VSI systems. So far, various PWM methods have been studied to reduce these CMV and DCC. However, they need to be fairly compared and evaluated together under the same condition to provide information so that power electronics engineers can select the appropriate PWM method when designing their motor drive systems. In this paper, the principle of these PWM methods is reviewed and their performance is analytically evaluated. Then, the PWM selection criterion is described based on the comprehensive evaluation studies. Lastly, the simulation and experimental results with an interior permanent magnet synchronous motor (IPMSM) drive system are presented to validate the presented PWM selection criterion.

Dead-Time Impact on the Harmonic Distortion and Conversion Efficiency in a Three-Phase Five-Level Cascaded H-Bridge Inverter: Mathematical Formulation and Experimental Analysis

To avoid leg short-circuit in inverters, dead time must be introduced on leg gate signals. Dead time affects the inverter output voltage fundamental harmonic amplitude, voltage harmonic distortion and inverter efficiency by introducing additional voltage drops. In this regard, dead time effects have been widely investigated for traditional two-level three-phase voltage source inverters in the literature but not extensively for multilevel topology structures. This paper provides a detailed analysis of dead time impact on the harmonic distortion and efficiency of Cascaded H-Bridges Multilevel Inverters (CHBMIs). For this purpose, a general mathematical formulation to determine voltage drop due to dead time effects, also taking into account the adopted Multicarrier PWM strategy, has been provided and experimentally validated for a five-level three-phase CHBMI structure. As a comparison tool between expected and ideal inverter output voltage, the percentage voltage error <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> % is introduced. In most of the cases, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> % is lower than 5%, and it starts increasing for very low amplitude modulation index or for specific working points where nonlinearities occur. Furthermore, several experimental investigations have been carried out to evaluate the CHBMI performance in terms of harmonic distortion and efficiency by changing, the values of dead time, modulation index and switching frequency for ten different multi-carried PWM strategies. Experimental results confirm the strong dependency between the dead time impact on the converter performance and the adopted Multi Carrier-PWM (MC-PWM) strategy: as a way of example, converter efficiency can be reduced from 80% to 60% when dead time is increased from 0.5 μs to 1.5 μs and Phase Shifted-PWM (PS-PWM) is adopted.

A Generalized Current Trajectory Based Fault Diagnostic Method for Three-Phase Two-Level Inverters

Inverters play a vital role in the distributed generated energy systems. Hence, the reliability of the entire distributed energy system depends on the consistent and continuous operation of the inverter. Consequently, to maintain a reliable operation, effective condition monitoring and fault diagnostic schemes have to be incorporated. In this paper, a method based on current trajectory is analyzed for the fault detection and diagnosis of open-switch faults in three-phase two-level voltage source inverters (VSI). The current trajectory-based method of fault diagnosis has been already presented literature for the identification and localization of open-switch fault in the three-phase two-level VSI. The main drawback of the existing current trajectory method is that the fault diagnosis and detection is dependent on the phase currents selected to plot the current trajectories. Therefore, in this paper, a generalization is proposed for the fault diagnosis and diagnosis based on the current trajectory, which make the method independent of the selection of the phase current used to plot the current trajectory. The validity and effectiveness of the proposed generalization is verified by simulation and experiments in a laboratory prototype of three-phase two-level VSI.

Compact SiC Power Module With Integrated Power Delivery and Cooling

As the transition from Si to SiC power devices rapidly grows, new packaging architectures need to be developed to fully benefit from the desired characteristics of SiC technology. The present study offers a highly integrated package (IP) with current carrier electrical feedthroughs that simultaneously combine power delivery and cooling functions. The thermal performance of the proposed solution is compared with the conventional package in a half-bridge configuration of a 50-kW two-level three-phase voltage source inverter (VSI). The specific thermal resistance of a power package is reduced by 13.5% in the proposed approach, showing an increased benefit at higher pumping power and heat flux conditions. Furthermore, design challenges are explored associated with the near-junction cooling as the performance is pushed toward 1 kW/cm2. Unlike the previous studies considering <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{j}$ </tex-math></inline-formula> as the main design constraint, the limiting parameter is found to shift to the maximum coolant temperature. With the design modifications focusing on overcoming the flash point limit of coolant, the specific thermal resistance is further reduced to 0.099 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}\cdot ^{\circ }\text{C}$ </tex-math></inline-formula> /W at 1 kW/cm2 at the expense of a 36.5% increase in the package volume. The findings of the study make a clear case for the need of innovative solutions to extract the highest benefit from integrated cooling at increased power density levels of next-generation inverters.

Finite Control Set Model Predictive Field-Oriented Control For Three-Phase Induction Motor Drives

Field-oriented control is one of the well-established vector control strategies for induction motor drives. However, its cascaded structure and requirement of a modulator for constant switching frequency operations makes it complex and computationally expensive. Model predictive control (MPC) is a novel control strategy used for AC motor drives. In this paper, a finite control set model predictive control (FCS-MPC) based field-oriented control (FOC) is presented. The Finite control set model predictive field-oriented control (FCS-MPFOC) utilizes a cost function that quantifies the error between the reference and anticipated current values for all the potential voltage vectors of the voltage source inverter. The voltage vector that generates the lowest value of the cost function is directly implemented on the inverter to produce the drive voltage. The efficiency of the proposed method is authenticated by using a three-phase induction motor, fed via a two-level three-phase voltage source inverter in the MATLAB/Simulink environment under various speeds, load torque, and model parameter mismatch situations. In order to authenticate the performance of the proposed strategy, it is compared with traditional model predictive torque control. Simulation results show that the proposed method performed significantly well in total current harmonic distortion, flux and torque ripples, switching frequency, and parameter variations.

Floating-capacitor based inverter for open-ended winding induction motor drive with fault-tolerance

ABSTRACT Floating-capacitor-based nine-level inverter topology for open-ended winding induction motor (OWIM) drive is presented in this paper. The proposed multilevel inverter topology (PMLIT) essentially consists of four three-phase two-level voltage source inverters (VSI), three isolated DC sources and a floating-capacitor (FC). Out of four inverters, three inverters are fed from DC sources, and the fourth inverter is connected with the FC. The advantage of the PMLIT is that the maximum output voltage will be twice the source voltage with nine levels across each phase winding. The PMLIT employs least number of components which makes the inverter cost-effective and has lowered control complexity. The PMLIT can deliver seven, five or three-level output voltage with a decrease in modulation index. Conventional sinusoidal pulse-width modulation (PWM) techniques can be employed to generate switch-gate pulses. The intermediate-voltage levels are realised by proper charging and discharging of the FC. The performance of the PMLIT under possible switch faults is investigated, and modified switching logics are proposed to deliver a balanced supply for the OWIM drive in post-fault operation. Simulations are performed in the MATLAB/Simulink environment, and an experimental setup is designed to validate the simulations, and the results are presented.

Carrier Selection Strategy of Generalized Discontinuous PWM Method for Current Reduction in DC-Link Capacitors of VSI

This article proposes a new carrier selection strategy of generalized discontinuous pulsewidth modulation (GDPWM) method for the two-level three-phase voltage source inverter to reduce the dc-link capacitor current under all operating conditions while keeping the minimum switching losses. First, the root-mean-square value of dc-link capacitor current is effectively reduced by selectively using both single and double carrier signals and modifying the switching patterns of existing GDPWM method. Although the proposed carrier selection strategy depends on the power factor (PF), the PF calculation is avoided because the multicarrier signals are properly chosen based on the information of three-phase modulation signals and measured three-phase currents. Also, the switching losses can be kept to a minimum as the modulation signals of conventional GDPWM method, which are optimal in terms of the switching losses, remain the same and the proposed carrier selection strategy has little effect on the total number of switching events. The operating principle of proposed GDPWM method is theoretically analyzed. Then, its practical effectiveness is verified by experimental tests on a motor drive system.

Machine-Learning-Based Diagnosis of an Inverter-Fed Induction Motor

The principal objective of this paper is to detect and automatically monitor switch open-circuit faults in a two-level three-phase voltage source inverter fed induction motor from the processing of its current signals. The proposed diagnostic method uses both signal processing techniques and machine learning techniques in order to detect and localize the switch under an open-circuit fault. First, the Hilbert-Huang transform using the empirical ensemble mode decomposition is employed for each phase current signal, which leads to extracting the intrinsic mode functions. In order to optimally choose the function indicating the open-circuit fault harmonic, two factors, namely, the root mean square and the correlation coefficient are calculated out for each function. In this regard, two criteria are proposed that lead to choose the optimal function giving better information about the defected phase. The spectral envelope of the optimal function permits extra0cting the fault harmonic of the switch. Second, different machine learning techniques are applied to locate and classify the switch open-circuit faults with the hyper-parameters optimization for a better design of the different models. Finally, a comparative study of the different machine learning techniques is carried out for determining the best classifier for the open-circuit faults. The experimental results effectively demonstrate a very high classification rate of 98.98%.

Evaluation and Minimization of Total Harmonic Distortion in Three-Phase Two-Level Voltage Source Inverter with Low Switching Frequency

Evaluation and Minimization of Total Harmonic Distortion in Three-Phase Two-Level Voltage Source Inverter with Low Switching Frequency

Evaluation and minimisation of total harmonic distortion in three-phase two-level voltage source inverter with low switching frequency

Evaluation and minimisation of total harmonic distortion in three-phase two-level voltage source inverter with low switching frequency

Simple FCS-MPC Method for Reducing Common-Mode Voltage in a Three-Phase Two-Level Voltage Source Inverter

Common mode voltage (CMV) causes various issues, including a negative impact on the performance of a hybrid electric vehicle’s power system (HEV). Many papers have published methods that mitigate CMV, almost all of which attempt to avoid zero vectors, but this increases total harmonic distortion (THD). This work describes a simple and efficient method for reducing CMV in a two-level three-phase voltage source inverter (VSI) with an RL load. This method uses only active vectors. It replace the zero vector with the two opposite vectors V2 and V5. for T1 and T2 respectively in a one sampling period Ts. A numerical simulation, using Matlab-Simulink. is achieved to assess the effectiveness of the proposed control technique. The obtained results show a reduction in THD value (17% improvement) and a decrease in the peak value of CMV from (${{ + {V_{dc}}} \over 2}$ and ${{ - {V_{dc}}} \over 6}$) to $\pm {{{V_{dc}}} \over 6}$. These results are compared to those obtained by using the traditional predictive control model MPC.

Innovative Fault-Tolerant Three-Phase SPMSM Drive Without Split Capacitors, Auxiliary Legs, or TRIACs

The existing fault-tolerant three-phase ac drives need split capacitors, auxiliary legs, and triode for alternating current (TRIACs) upon a standard three-phase two-level voltage source inverter (VSI) to obtain the self-healing ability toward open-phase faults (OPFs). In order to reduce the cost, volume, and weight, this article proposes a novel fault-tolerant three-phase surfacemounted permanent magnet synchronous machine (SPMSM) drive without split capacitors, auxiliary legs, or TRIACs. The proposed drive is still built upon a three-phase two-level VSI, whereas its dc-source is directly connected to the neutral point of the motor. First, mathematical model and equivalent circuit are established to reveal the existence of an equivalent dc/dc boost converter in the drive system. Second, the brand-new d-0 axes current references are proposed in order to preserve the motor's performance when an OPF occurs. In this case, both id and i0 are nonconstant. Third, an overall control strategy including the healthy and fault-tolerant modes is presented. In the fault-tolerant mode, a deadbeat current controller is developed to track the nonconstant current references. Finally, experiments are carried out on an SPMSM test-bench to verify the effectiveness of the proposed scheme.