Zero-sequence Circulating Current Research Articles

Multi-target fault ride-through strategy for transformerless MMCs under asymmetric grounding faults in AC/DC hybrid distribution networks

In AC/DC hybrid distribution networks (HDNs), when asymmetric grounding faults occur, transformerless multiterminal modular multilevel converters (MMCs) should achieve three key targets of fault ride-through (FRT): 1) limiting the unbalanced fault currents; 2) injecting currents to support grid voltages in case of disconnection from grids; and 3) eliminating the zero-sequence circulating currents (ZSCCs) from fault networks through MMCs to nonfaulted networks. However, in medium voltage-level HDNs, the line impedances are mainly resistive-inductive, and traditional current injection methods are no longer effective. Moreover, in neutral nondirect grounding networks with multiple AC voltage levels, the voltages of nonfaulted phases rise, and it is difficult for MMCs to achieve fault current control. To solve the above issues, this manuscript proposes a multi-target FRT strategy. First, negative-sequence current controllers are used to eliminate the negative-sequence fault currents. Then, to support the positive-sequence voltages of grids, optimal and suboptimal active-reactive current references based on the line impedance ratios are proposed. To help transformerless MMCs with low modulation indices eliminate zero-sequence circulating currents, two zero-sequence voltage compensation modes and an improved zero-sequence current eliminator are proposed. Finally, the proposed fault current control is verified in MATLAB/Simulink.

Multivector Model Predictive Current Control for Paralleled Three-Level T-Type Inverters With Circulating Current Elimination

Paralleled three-level T-type inverters face the unavoidable pitfall of the zero-sequence circulating current (ZSCC). Although the conventional model predictive control (MPC) could eliminate the ZSCC, the control error occurs inevitably since only one vector is adopted in each sampling period, which decreases the current control performance. Thus, simultaneous ZSCC elimination and accurate current tracking become imperative to the inverter using MPC. This article proposed a multi-vector MPC to eliminate the ZSCC and reduce the current distortion without the weighting factor. As the common-mode voltage (CMV) and neutral point (NP) voltage are the main factors that induce the ZSCC, the virtual vector with zero-average CMV is constructed to eliminate the ZSCC. Meanwhile, the small vector is introduced to improve the NP voltage control capability. Additionally, to enhance the current accuracy and reduce the ZSCC ripple, three optimal vectors are adopted to synthesize desired voltage. Moreover, the multi-vector preselection algorithm is proposed to reduce the computational complexity of implementation process. Finally, the effectiveness of the proposed method is verified with comprehensive simulation and experimental results.

Impartial Sequential Model Predictive Control of Parallel T-Type Rectifiers for Power Sharing and Circulating Current Elimination

A parallel T-type rectifier connection is often required to improve the system capacity and stability in high-power applications. However, the parallel rectifier faces the challenges of zero-sequence circulating current (ZSCC) elimination, neutral point (NP) voltage balance, DC voltage stability and power sharing. First, to solve the multi-objective optimization problem of two parallel three-level T-type rectifiers with LCL filters (LCL-3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Rs), a double closed-loop control scheme is adopted. In this scheme, an impartial sequential model predictive control (ISMPC) is proposed as the inner-loop controller for ZSCC elimination and NP voltage balance, and an adaptive droop control with voltage feedforward is designed as the outer-loop controller to achieve DC voltage stability and power sharing for each rectifier based on its capacity. Second, the main influencing factors of ZSCC in LCL-3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Rs are analyzed, and ZSCC elimination is considered as one control objective in ISMPC. Finally, ISMPC is proposed to solve the problem that sequential model predictive control (SMPC) could not select the optimal solution due to the fixed priority and the excessive process only controlled a single objective. The proposed method is tested on a prototype hardware platform of a 10-kW and a 5-kW parallel rectifier. Experiment results demonstrate the superiority of this method over existing methods under several typical scenarios.

Active Vector Modification for Circulating Current Suppression of Paralleled Inverters Using Two-Step Sector Indexing-Based Discontinuous SVPWM

Due to the discrepancy of paralleled inverters, the zero-sequence circulating current (ZSCC) is a critical issue in a paralleled inverter fed permanent magnet synchronous machine (PMSM) drive system. The conventional solution to this issue is to adjust the duration of two zero vectors, however, will not be appropriate under the discontinuous space vector pulse-width modulation (DSVPWM) control using only one zero vector. For overcoming the above issues, an active vector modification based ZSCC suppression and a two-step sector indexing based DSVPWM are proposed in this paper. It uses both reference voltage and current vectors to jointly determine the drive signals in a two-step manner, which avoids the circulating current jump due to the coexistence of different zero vectors and can also reduce the switching loss by 50% in theory. Meanwhile, the low-frequency ZSCC can be online suppressed by a proposed real-time modification of durations of active vectors, which is finally verified together with the proposed two-step sector indexing method on a PMSM fed by two paralleled inverters.

Improved Finite-Time Control for Circulating Current Suppression of Multiparalleled Rectifiers

Multi-paralleled three-level rectifiers (MP3LRs) have the advantages of higher-power rating and higher reliability. However, the zero-sequence circulating current (ZSCC) will occur when MP3LRs are connected to a common dc bus, which will distort the grid current, and threaten the safe and reliable operation of MP3LRs. Significantly, the ZSCC suppression of the MP3LRs is rarely studied. To overcome the limitation, an improved ZSCC suppression method for MP3LRs is proposed in this paper. Firstly, a ZSCC model of the MP3LRs system is established. Secondly, according to the ZSCC model, the ZSCC controller based on “Finite-time control + Feedforward” is designed, and the strict theoretical proof of system stability is carried out. Thirdly, this method is realized by using the output of ZSCC controller to modify the three-phase switching time of multiple rectifiers (2nd to Nth rectifiers). Consequently, the method proposed in this paper can suppress the ZSCC of MP3LRs, completely. Compared with the conventional ZSCC suppression methods, the proposed method has better ZSCC suppression performance and stronger anti-interference capability. Meanwhile, it does not increase any hardware cost. Finally, simulation and experimental results verify the effectiveness of the proposed method.

Nonlinear Modeling and Improved Suppression of Zero-Sequence Circulating Current for Parallel Three-Level Inverters

The parallel operation of three-level inverters can increase the current capacity and power rating of the system. However, the problem of zero-sequence circulating current (ZSCC) inevitably emerges due to the common-mode voltage difference (CMVD) between the parallel three-level inverters (PTLIs). Especially, the inverter nonlinear characteristics (INCs) will worsen the ZSCC problem and weaken the suppression effect of ZSCC. In this paper, a nonlinear equivalent model of ZSCC is established considering the INCs. Then, the simplified graphical analysis method is proposed to implement the frequency analysis of ZSCC. Furthermore, an improved ZSCC suppression strategy for the PTLIs is proposed. The INCs and original CMVD are regarded as the total disturbance and a nonlinear disturbance observer (NDOB) is designed to estimate it. Based on the NDOB, a feedback-feedforward control method is adopted to suppress ZSCC. According to the amplitude-frequency characteristics of the closed-loop control system, the controller parameters design and performance analysis are performed. The control structure is simple, the parameter design is convenient, and the suppression effect of ZSCC is evidently improved. Finally, the simulation and experimental results verify the validity of proposed strategy.

Modeling and Suppression of Zero-Sequence Circulating Current Resonance for Parallel Interleaved Inverters With Bypass Capacitor-Based Leakage Current Mitigation

Connection of the neutral point of the ac capacitor to the midpoint or positive (negative) rail of the dc link is a cost-effective method to suppress the leakage current to ground. However, applying it to a modular parallel interleaved inverter system with the common ac and dc bus will induce zero-sequence circulating current (ZSCC) resonance issue. This paper firstly establishes the common mode equivalent circuit model of the multi-parallel inverters system. Secondly, the generation mechanism of ZSCC resonance is investigated based on the installed impedance model. To guarantee the stable operation, the resonance suppression method which combines the sampling instant shift and phase lag compensation is proposed. The frequency aliasing phenomenon and resultant ZSCC dc offset issue due to the sampling instant shift are further analyzed, and an effective suppression scheme of the ZSCC dc offset is proposed by adding an additional ZSCC dc offset control loop. Finally, the comparative experiments verify the effectiveness of the proposed method.

Virtual Voltage Vector-Based Sequential Model-Free Predictive Control for Multiparalleled NPC Inverters

Parallel inverters are widely used in the micro-grid systems to meet the demand for increased power capacity and enhanced reliability. However, unbalanced connections between the parallel inverters may cause a spike in the zero-sequence circulating current (ZSCC), leading to performance degradation. To address this issue, a virtual voltage vector-based sequential model-free predictive control method is proposed in this paper for parallel converters. Specifically, extended state observer (ESO) and virtual voltage vectors are introduced into the finite control-set model predictive control (FCS-MPC) architecture to cope with the multi-objective including ZSCC inhibition and robustness performance improvement. Next, to prevent the adjusting of weighting factors, a sequential model-free predictive control solution is constructed. The main feature of the proposed control methodology is that the reliability and robustness of the controlled system can be significantly enhanced without knowing the accurate mathematical models and parameters. Finally, the effectiveness of the suggested approach is verified by performance evaluation.

PROPORTIONAL INTEGRAL QUASI RESONANT CONTROLLER FOR ZERO-SEQUENCE CIRCULATING CURRENT AND RIPPLES SUPPRESSION IN PARALLEL THREE-PHASE PWM RECTIFIERS

Parallel three-phase pulse with modulation (PWM) rectifiers with common sc and ac buses are widely used in power systems due to their many advantages such as flexibility, sinusoidal grid currents, lower switching frequency, and good reliability. However, this topology suffers from zero-sequence circulating current (ZSCC) generated by numerous reasons including filters inductors unbalanced, unequal dead time, and losses of synchronism between the control of each rectifier, which will distort the ac-side currents and increase power losses. This paper proposes both an adjusted space vector pulse width modulated (ASVPWM) method and proportional integral quasi resonant controller (PIQRC) method not only to force the ZSCC to be zero but also to reduce its ripples, which results in low frequency harmonic components in the ac side currents. This twofold objective can be achieved by adjusting the zero-vector duty ratios of ASVPWM to suppress the ZSCC and by using PIQRC to mitigate its predominant harmonics. Finally, the superiority and efficiency of the proposed control method in terms of ZSCC suppression and current ripple reduction are verified through comparative analysis with the conventional ZSCC-PI controller.

The Zero-Sequence Circulating Current Suppression Method for Parallel Three-Level Rectifiers System Under the Open-Circuit Fault of Neutral-Point Switches

In parallel T-type three-level rectifiers system (PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs), when the open-circuit fault (OCF) of neutral-point (NP) switches occurs, the existing zero-sequence circulating current (ZSCC) suppression methods are not capable of suppressing the ZSCC any more since the ZSCC model of PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs is changed. Significantly, the ZSCC suppression issue of PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs under the OCF of NP switches has not been researched in previous literatures. To overcome this limitation, a novel ZSCC suppression method for PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs with the OCF of NP switches is proposed. First of all, according to the principle of area equivalence, the fault-tolerant control (FTC) is accomplished by reconstructing the switching sequence. Second, a novel ZSCC model with FTC is established. Then, according to the novel ZSCC model, the ZSCC control method based on “PI + feedforward” is proposed. This method is realized by modifying the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> time of three-phase of fault rectifier in PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs. Consequently, the method proposed in this article effectively restrains the ZSCC of PT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 3LRs with the OCF of NP switches. Finally, the simulation and experiment results verified the correctness of proposed method.

Zero-Sequence Circulating Current Analysis and Suppression for Multimodular Interleaved Parallel Inverters

Modular interleaved parallel inverters with shared dc and ac bus will introduce the zero-sequence circulating current (ZSCC) between the paralleled modules. Larger ZSCC may increase the current stress of power switches and reduce system efficiency. In this article, the ZSCC equivalent circuit model with multimodular interleaved parallel inverters is established. The influences of different factors such as carrier phase shifting, unequal current references, dead time, and unequal inductors on the high-frequency ZSCC (HF-ZSCC) and low-frequency ZSCC (LF-ZSCC) are analyzed in the frequency domain. An interleaved zero vector modulation method is proposed together with a plug-in repetitive controller to suppress HF-ZSCC and LF-ZSCC simultaneously. With the proposed method, parallel modules can be implemented in a self-governing manner, which presents high reliability and scalability. The effectiveness of the proposed scheme is verified by the experimental results.

A Modified DPWM Method With Minimal Line Current Ripple and Zero-Sequence Circulating Current for Two Parallel Interleaved 2L-VSIs

High-performance comprehensive optimization of line current ripple, zero-sequence circulating current (ZSCC), and switching losses is a challenge for parallel interleaved inverters. This article proposes a modified discontinuous pulse width modulation (PWM) method for two parallel interleaved two-level voltage-source inverters (2L-VSIs), which are regarded as a single 3L-VSI to optimize its vector sequence. The line current ripple is the priority optimization target to guarantee the principle of the nearest three vectors is applied in each subsector. To reduce the ZSCC and switching losses, the vector combinations with smaller changing rate of ZSCC are selected, and the phase-leg carrying the highest current is clamped. The detailed design procedure of 3L-vector sequence and how to distribute to 2L-VSIs are revealed. The quantitative performance comparison between the proposed PWM method and existing ones in terms of line current ripple, ZSCC, and switching losses are made. Experimental results confirm the effectiveness of the proposed method.

Fault-Tolerant Sequential MPC for Vertical Switch Open-Circuit Fault and ZSCC Suppression for Parallel T-Type Converters

A fault-tolerant control (FTC) is proposed for enhancing the reliability of power electronic systems. The software-based FTC of parallel-connected three-level T-type converters (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cs) for suppressing zero-sequence circulating current (ZSCC) induced by a vertical switch open-circuit fault is investigated. A simplified sequential model predictive control (SSMPC)-based FTC technique is developed. Parallel-3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cs and their prediction models are introduced, followed by an SSMPC for the no-fault condition. The model inaccuracies under vertical switch faults are elaborated. For the faulty 3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> C, two fault-tolerant SSMPC (FT-SSMPC) methods are provided by creating a sequential predictive controller that considers ZSCC suppression and grid current tracking. The control policies for the ZSCC are changed from the standard feedback-free to feedback-based cost function (CF) optimization using the unimproved FT-SSMPC. Furthermore, an improved FT-SSMPC is proposed using a phase-deficient CF, which increases the accuracy of the mathematical relation of the fault condition. After fault diagnosis, the proposed method achieves neutral-point voltage balance and excellent point-of-common-coupling current, effectively suppresses the ZSCC, and increases the control reliability. Finally, experiments demonstrate the effectiveness of the proposed FT-SSMPC under various conditions.

The Tolerance Control Method Based on Zero-Sequence Circulating Current Suppression for Parallel T-Type Three-Level Rectifiers

Zero-sequence circulating current (ZSCC) suppression and fault-tolerant control (FTC) are important guarantees for the safe and reliable operation of parallel T-type three-level rectifiers <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$({\mathrm {PT}}^{2}3{\mathrm {LRs}})$ </tex-math></inline-formula> . However, none of the existing literature can solve the FTC under the ZSCC suppression of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {PT}}^{2}3{\mathrm {LRs}}$ </tex-math></inline-formula> when the open switch fault (OSF) occurs in neutral-point (NP) switches. In order to solve these issues, a novel FTC method based on ZSCC suppression is proposed in this article. First, an improved finite-time controller is constructed to suppress the ZSCC by adjusting the difference of zero-sequence duty ratio between two rectifiers, completely. Then, based on the principle of area equivalence, the switching sequence is reconstructed by changing the state switching mode of the fault phase in real-time. As a result, the FTC under the OSF of NP switches is realized without affecting the suppression of ZSCC. Compared with the existing methods, the proposed method not only realizes the suppression of the ZSCC of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {PT}}^{2}3{\mathrm {LRs}}$ </tex-math></inline-formula> but also completes the FTC under the OSF of NP switches, which guarantees the ZSCC suppression ability under the OSF of NP switches. Consequently, the power quality of the ac side of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {PT}}^{2}3{\mathrm {LRs}}$ </tex-math></inline-formula> is improved significantly during the normal operation and the operation under the OSF of NP switches. Thus, the safe and reliable operation of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {PT}}^{2}3{\mathrm {LRs}}$ </tex-math></inline-formula> is guaranteed effectively. Finally, the feasibility and correctness of the proposed method are verified by experiment results.

An improved data-driven based model predictive control for zero-sequence circulating current suppression in paralleled converters

To address the requirement of improved power capacity, reliability and operation, parallel converters have been widely applied in micro-grid. However, the connections between DC and AC sides of different parallel converters may lead to the surge of zero-sequence circulating current (ZSCC), which would result in the deterioration of system functionality. Regarding the stated problem above, this paper proposes an improved data-driven based model predictive control for parallel converters. Specifically, a model-free adaptive control (MFAC), which is based on the measured input/output data, is incorporated into the finite control-set model predictive control (FCS-MPC) framework with multi-objective constraints, thus allowing for the suppression of ZSCC and the improvement of robustness performance. Furthermore, to avoid the tuning of weighting factors, a novel cost function is constructed based on the multi-objective decision making method. The main contribution of the proposed methodology relies on the fact that no knowledge of any model parameters and weighting factors in whole control process are required, which leads to a significant enhancement in the robustness and reliability of the control system in the presence of parametric uncertainties. Furthermore, by this proposal, the accurate current tracking and ZSCC suppression can be achieved. Finally, the validity of the proposed FCS-MPC scheme is verified by comprehensive case studies.

Integrated Modulation of Dual-Parallel Three-Level Inverters With Reduced Common Mode Voltage and Circulating Current

Many reduced common mode voltage (CMV) modulation methods have been proposed for three-level inverters. However, most of them suffer from large current distortion because only part of the available base vectors is utilized. The interleaved paralleling can reduce both CMV and the output current distortion, though the CMV reduction is limited and large zero-sequence circulating current (ZSCC) is inevitably caused by the phase-shifted carriers. To further reduce the CMV while maintaining smaller current distortion and ZSCC, a five-level reduced CMV (RCMV) modulation method is proposed in this article, which treats the parallel inverters as a whole. Theoretical analysis reveals that the integrated modulation provides additional base vectors that contribute to smaller total harmonic distortion (THD) of the current, and the selected vectors ensure the nearest-three-vector synthesis and half-reduced CMV. The switching sequences design and neutral point balancing strategy are also developed for dual-parallel three-level inverters, ensuring that the average circulating current is zero and the neutral point voltage is balanced, which are both critical to the proper operation of parallel inverters. Superior performance in terms of CMV, THD, and ZSCC provided by the proposed method in comparison with conventional modulation is verified by comprehensive simulation and experimental results.

Model Predictive Current Control Based on Virtual Voltage Vector Method for Parallel Three-Level Inverters

The parallel three-level neutral-point clamp (3L-NPC) inverters are widely solicited today to satisfy the higher power demand by using low-rated switching devices in industrial applications such as renewable power generation. With the 3L-NPC in parallel, the zero-sequence circulating current (ZSCC) occurs in the closed circuit and decreases the performances of the current response if the two 3L-NPCs share the same dc bus with no galvanic isolation at the ac side. From the analysis of the ZSCC equivalent circuit, the virtual voltage vectors are proposed and exploited by the finite control set model predictive control (FCS-MPC) for mitigating the ZSCC and improving the current accuracy. In order to keep the neutral-point balance and reduce the switching loss, the differential capacitor voltage and the average switching frequency are considered in the proposed MPC. An experimental platform based on the Simulink-Real-Time system is presented for further verification of the effectiveness of the proposed method. The simulation and the experimental results obtained under the proposed strategy show that the ZSCC is reduced to near zero, and the current response provided has lower THD.

Circulating current reduction-based hybrid controller of an electrical drive system fed by two parallel inverters

This paper presents a control technique of an electrical drive system fed by two parallel-connected voltage source inverters (VSIs). Two types of controllers are used to ensure a correct control of the system under different situations, especially, in case of structural or control imbalances between the two VSIs, which leads to parasitic zero-sequence circulating currents (ZSCC) appearance. So, a linear PI controller and a nonlinear sliding mode controller are combined together to act simultaneously based on the frequency separation principle and form hybrid controller. Therefore, the designed controller allows reduced ZSCC and offers stability and robustness against external disturbances. Simulation and experimental investigations shown that the proposed hybrid controller ensures the control of the drive system with ZSCC suppression even in the presence of imbalances.

Circulating Current Mitigation and Harmonic Current Compensation for Multifunction Parallel Three-Level Four-Leg Converters

The multifunction parallel three-level four-leg converters are proposed for high-power applications, which combine grid-connected renewable generation and active power filter (APF). However, the challenge of zero-sequence circulating current (ZSCC) is inevitable which degrades the output currents’ quality and reduces the stability of the system. To overcome this limitation, a proportional integral (PI) + feedforward control strategy and space vector modulation based on the nonaxial redundant vectors (NARVs) are proposed in this article. First, the model of ZSCC is established and analyzed in detail. The analysis reveals that ZSCC is determined by zero-sequence duty-cycle difference and zero-sequence benchmark function. Then, by analyzing the space vector of the three-level four-leg converter, it is concluded that ZSCC is affected by different NARVs. Consequently, a PI + feedforward control strategy is proposed to mitigate ZSCC by adjusting the duty cycle of NARVs in each pulse width modulation (PWM) sampling period. The simulation and experimental results verify the effectiveness of the proposed control strategy.

A Fast-Processing Predictive Control Strategy for Common-Mode Voltage Reduction in Parallel Three-Level Inverters

Model predictive control (MPC) is an attractive control scheme, in particular, for multilevel converters. However, MPC suffers from high computational burden and tedious tuning of weighting factors especially for parallel three-level inverters. Moreover, the parallel three-level inverters will unavoidably face the challenge of maintaining low circulating current, reducing common mode voltage (CMV), and balancing neutral point (NP) voltage in practice. Therefore, in this article, a fast-processing predictive control strategy is proposed for reducing the zero-sequence circulating current (ZSCC), NP voltage imbalance and CMV simultaneously in parallel three-level inverters. Based on the selected sector by the reference voltage vector, the proposed fast-processing predictive control takes feasible five or six candidate vectors into account; therefore, the computational burden, which is a disadvantage of the predictive control for inverters, will decrease. In addition, the proposed method eliminates the weighting factor, which avoids tedious tuning work. In the proposed control scheme, the candidate vectors are selected for ZSCC, NP voltage imbalance, and CMV reduction, and then, among them, the optimized switching vector is selected by optimizing the cost function. The performance of the proposed method has been validated by the simulation and experimental results.