The electric-drive-reconstructed onboard charger (EDROC) for solar-powered electric vehicles (SPEVs) utilizes zero-sequence current (ZSC) to charge the battery in both DC charging and in-motion charging modes. However, this introduces a zero-sequence torque (ZST) ripple, which jeopardizes operational safety during DC charging and adversely affects motor stability during in-motion charging. To address this issue, this paper proposes a q-axis current injection strategy that generates a compensating torque to counterbalance the ZST. Furthermore, to ensure accurate injection and avoid performance degradation due to permanent magnet flux variation, a generalized integrator extended state observer (GI-ESO) is designed to estimate the 3rd harmonic flux. Firstly, the topology of the EDROC and the mathematical model of the symmetrical six-phase permanent magnet synchronous motor (S6-PMSM) are analyzed. Then, the q-axis current injection strategy and the GI-ESO based 3rd harmonic flux estimation method are described in detail. Finally, experiments on a 2-kW laboratory prototype verify the effectiveness of the proposed torque ripple suppression strategy under various operating conditions.

Owing to the multi-degree-of-freedom characteristics and inherent fault-tolerant capacity, six-phase motors have been widely adopted in high-power applications, such as electric vehicle propulsion and aerospace systems. This paper presents the fault-tolerant control strategy of symmetrical six-phase permanent magnet synchronous motor (SSPMSM) under an isolated neutral point topology and proposes a fault diagnosis scheme based on joint diagnosis of multiple variables. First, two mathematical models of SSPMSM and their relationship are established. Subsequently, the current vectors in the torque subspace and harmonic subspace of the two winding sets under fault conditions are analyzed, and the cause of post-fault torque ripple is explained as resulting from controller conflict. In addition, a multivariate fault diagnosis scheme based on voltage threshold in the $\boldsymbol{x}-\boldsymbol{y}$ subspace and current trajectory characteristics in the $\boldsymbol{\alpha}-\boldsymbol{\beta}$ subspace is proposed to enhance the diagnostic accuracy. Finally, the feasibility and stability of the proposed control and diagnosis methods are verified by experiments.

2×3-phase surface-mounted permanent magnet synchronous motor (SPMSM) is gaining increasing attention due to its strong reliability and redundancy characteristic, in which winding configuration plays a crucial role. However, most existing research focus on fault-tolerant control strategies, and there are few research on the comprehensive comparisons of the performance under normal and faulty operations for different connection modes. In this article, the mono-inverter parallel drive method is employed to smaller the size and reduce the cost of drive system. Additionally, theoretical derivation is conducted for mathematic models under different connection methods, as well as under normal and passive fault-tolerant conditions. Furthermore, the comprehensive evaluation of all connection modes is conducted. Finally, the experimental results validate the correctness of the above theoretical analysis.

Purpose This study aims to enhance the performance of sensorless vector control for permanent magnet synchronous motor (PMSM) drives by developing an improved sliding-mode observer (SMO) with current disturbance compensation (CDC). This observer is designed to achieve chattering attenuation induced by sliding-mode dynamics while improving the estimation accuracy of both current and rotor position parameters. Design/methodology/approach To address the chattering and disturbance rejection shortcomings of conventional first-order SMOs, this paper proposes a higher-order SMO based on a hyperbolic tangent sliding surface (HTSMO) and then deeply integrates it with CDC, forming the CDC-HTSMO. First, a hyperbolic tangent sliding-mode surface is designed to achieve chattering suppression. Then, considering external current disturbances, CDC is added to the observed current to reduce current errors. Findings Comparative experiments are conducted to verify the effectiveness of CDC-HTSMO in current disturbance and rotor position compensation. The final results demonstrate that the proposed method exhibits excellent performance in reducing chattering, suppressing current ripple and improving rotor position estimation accuracy. Originality/value The improved observer proposed in this study is co-developed and experimentally validated with SMO based on a first-order sliding-mode framework and an extended-model-based full-order sliding-mode observer. Systematic comparative analyses are conducted under diverse operating conditions, including speed variations, no-load/load disturbances and parameter variations.

The dual-channel electric-drive-reutilized onboard charger (EDROC) originates from the design philosophy of the dual-channel electric drive system. It features a modular design and high reliability, making it highly suitable for electric vehicles (EVs). However, multiphase motors are susceptible to open circuit faults, which can cause the system to malfunction. To address this issue, this paper investigates an undisturbed operation of the dual-channel EDROC, which integrates a symmetrical six-phase permanent magnet synchronous motor (SSPMSM) drive. First, the vector space decomposition (VSD) technology is employed to decouple the winding currents under prefault- and postfault conditions, demonstrating that a charging torque exists in the motor during a single-phase open circuit fault. Then, a subspace current injection strategy is proposed by deducing the relationship between alpha-beta subspace currents and rotor angle, which achieve zero charging torque at almost all rotor angles. On this basis, rotor angle under the constraint of minimum copper is derived by constructing the objective function. Subsequently, an undisturbed operation controller is developed for prefault and postfault conditions. Finally, the feasibility and reliability of the proposed method are validated experimentally.

Traditional single-phase electric-drive-reconstructed onboard chargers (EDROCs) are widely adopted owing to their high integration density and accessibility. However, a bulky dc-link capacitor is usually required for power ripple suppression, and the incomplete cancellation of magnetomotive force leads to charging torque fluctuation, thus degrading the power density and reliability. To address these problems, this article proposes a novel EDROC topology under the criteria of minimum torque fluctuation. Two windings and the corresponding bridge arms of a symmetrical six-phase permanent magnet synchronous machine (SSPMSM) are first reconfigured as a series inductance-based active filter (AF) to suppress the power ripple. Different topologies with various winding selections are then evaluated to ensure standstill operation during charging. The optimal topology is subsequently identified for minimum torque fluctuation. An integrated control strategy combining bridgeless power factor correction (PFC) and AF current compensation is further developed. Finally, experimental results obtained from a 1kW laboratory prototype verify the effectiveness of the AF and the validity of the selected topology.

Model-free predictive control (MFPC) based on ultra-local model (ULM) is characterized by enhanced robustness to parameter mismatches. However, the selection of control gains, actually, still relies on the parameters, and the gain deviation degrades the control performance. To solve this issue, this article proposes an improved MFPC with a novel input-output-variation-driven gain observer. With a conceptual ULM-based MFPC, the impacts of gain deviation on the control performance and system stability are analyzed in detail. Then, the proposed method is expatiated, and in particular the stability of the proposed gain observer is proven based on the Lyapunov stability theorem. Meanwhile, the design guideline of feedback coefficients of the proposed observer is also presented. Based on the theoretical analyses, a finite-control-set model-free predictive current control (FCS-MFPCC) method with the suppression of gain deviation is designed and applied to a permanent magnet synchronous machine (PMSM) drive system. The digital delay compensation and the discriminator of zero-voltage vectors are considered for performance improvement and inverter switching frequency reduction, respectively. Finally, some critical experiments are conducted based on a PMSM test rig to verify the proposed gain observer and FCS-MFPCC method. In particular, different initial values of control gains are set, indicating that the proposed FCS-MFPCC method does not require any prior knowledge of electrical parameters of the PMSM under test.

The concept of multiplexing power legs makes series-end winding permanent magnet synchronous machines (SEW-PMSMs) have the merits of high DC-link voltage utilization, low volume, and high efficiency. However, the increased leg current of multiplexing power legs inevitably leads to high power loss of converter. Besides, the multiplexing power legs also have a large weight in the common-mode voltage from machine sides, which leads to large amplitude and dv/dt stress of common-mode voltage, compared with nonmultiplexing ones. Therefore, although multiplexing power legs brings apparent superiorities to SEW-PMSM, they lead to several impairments as well. Consequently, an optimized discontinuous space vector modulation (ODSVM) strategy is proposed in this article, where the switching action reduction focuses on the multiplexing power legs to reduce the power loss and amplitude of common-mode voltage caused by the above legs. Furthermore, a spatial near state SVM (NSSVM) scheme is proposed to reduce the common-mode voltage from the converter/machine sides. Two proposed discontinuous space vector modulation (DSVM) strategies are verified and compared with traditional continuous SVM (CSVM) and three existing DSVM methods by experimental results. The effective common-mode voltage and/or power loss reduction are verified experimentally in the proposed DSVM strategies.

Dual three-phase permanent magnet synchronous motors (PMSMs) have excellent properties. However, an unavoidable power supply unbalance exists under dual DC power source configurations. To address this, an improved online space vector modulation (SVM) strategy incorporating harmonic current injection is proposed in this paper. First, to deduce the injected index of the harmonic currents, the relationship between the fundamental and harmonic currents is researched. Second, each subspace is tracked by four voltage vectors, and an improved online modulation method is proposed to eliminate offline tables, thereby simplifying calculation. Finally, experimental results verify the effectiveness of the proposed strategy under unbalance DC-link voltages, presenting superior characteristics in terms of a substantial reduction in both the current total harmonic distortion and action time compared to traditional methods.

To overcome the challenges of high computational burden and insufficient control accuracy in three-vector-based model predictive current control (TV-MPCC) strategies, this article proposes an improved TV-MPCC for permanent magnet synchronous motor (PMSM) drive systems fed by 3L-NPC inverters. By integrating voltage vector preselection with a low-complexity optimization strategy, the proposed method significantly reduces computational burden while maintaining excellent control performance even under overmodulation conditions. First, a two-stage voltage vector preselection strategy is developed to efficiently identify candidate vectors, reducing the number of evaluated vectors from 27 to approximately 10 and significantly lowering computational complexity. Meanwhile, a corresponding duty cycle calculation method based on voltage error parameters is designed to reduce the explicit dependence on multiple motor parameters. Furthermore, an optimized voltage vector (VV) combination strategy and a low-complexity overmodulation method are designed, thereby constructing a unified TV-MPCC framework applicable over the full modulation range. Finally, experimental results demonstrate that the proposed method significantly shortens computation time, improves voltage utilization, and reduces current harmonic distortion.

Aiming at the defects of traditional fault-tolerant control (FTC) and fault detection systems, a diagnosis-free passive FTC (PFTC) scheme for nx3 phase surface-mounted permanent-magnet synchronous motors (SPMSMs) with connected neutral point is proposed. To reduce the cost, volume, and complexity of the driver, this article adopts a mono-inverter parallel drive for nx3 phase motors, which is a prerequisite for achieving passive fault tolerance. By combining the i(d)=0 control strategy and field-oriented control (FOC) technology of the traditional three-phase PMSMs, the self-healing capability can be realized after nx3 phase SPMSMs experience double-phase open-circuit faults. Due to the proposed PFTC scheme not requiring the fault diagnosis process, the impact of misdiagnosis and diagnostic delays can be fundamentally avoided. In addition, there is no need to optimize the modulation strategy, motor model, or reference current before and after the fault, thus enabling smooth switching between different operating states. The proposed PFTC scheme can not only achieve seamless switching under multiple operating conditions but also be simple and easy to operate. The experimental results are carried out to verify the effectiveness and feasibility of the proposed method.

Misalignment tolerance is critical for inductive power transfer (IPT) systems. This paper introduces an innovative asymmetric coupler based on an I-shaped magnetic core structure, significantly improving output voltage stability under horizontal and vertical displacements. Unlike conventional cubic magnetic cores, the I-shaped core enhances flux concentration by enlarging its ends while narrowing the middle section, effectively reducing the demagnetization factor and boosting magnetic focusing capability. The design optimization process for minimizing the demagnetization factor is thoroughly analyzed. Comparative experiments with traditional cubic-core asymmetric couplers demonstrate the proposed structure’s superior magnetic coupling and misalignment resistance. Experimental results show that the I-shaped core IPT system achieves a 23% lower output voltage fluctuation and 5% higher efficiency compared to its cube core counterpart.

Six-phase permanent magnet synchronous machine (PMSM) under dual battery supplies has the advantages of strong fault tolerance, high control freedom, convenient modular drive and high efficiency. However, unbalanced battery power supply leads to unbalanced current between channels, which reduces the load capacity and control performance of the motor. In this paper, an inter-channel current balancing control strategy based on extended state observer-based proportional-integral (ESO-PI) controller is proposed to solve this problem. This method estimates and compensates the x-y subspace distortion current caused by unbalanced power supply in real time and then suppresses AC component of the subspace. Thus, inter-channel current balance ability, the load capacity and fault tolerance of the system are guaranteed. Firstly, the mathematical model of the six-phase PMSM under dual battery supplies is established by using vector space decomposition (VSD) theory, and the impact of unbalanced power supply is thoroughly analyzed. Subsequently, ESO-PI controller is designed to estimate the x-y subspace current and the total disturbance. The performance of the proposed strategy in the suppression of medium and low frequency AC components is analyzed theoretically. Finally, experimental results under various operating conditions verify the superiority of the proposed control strategy.

Purpose As the new energy vehicle industry advances, the demands for motors’ speed regulation range and power density are steadily rising. This paper aims to design a motor that combines high efficiency with a wide high-speed range and high power density. To achieve this, a negative-salient permanent magnet synchronous motor is proposed (NSPMSM). Design/methodology/approach This paper presents a new NSPMSM topology for vehicles, which is based on the conventional interior permanent magnet synchronous motor. Firstly, the current trajectories in various operating regions of the NSPMSM are analyzed, along with the effect of the saliency ratio for the distribution of dq-axis current. Secondly, the field-circuit co-simulation framework is built based on the finite element method, using Maxwell-Simplorer-Simulink Real-time data exchange between different software tools allows for transient simulation of the model under varying operating conditions. Through simulations, the laws of distribution of dq-axis current, current variations under changing conditions, and transient data of the NSPMSM are verified. Additionally, the speed range of constant power and full-speed domain efficiency of the NSPMSM are analyzed. Findings The results indicate that compared to conventional motors, the NSPMSM increases the speed range from 4.5:1 to 6.5:1, effectively broadening speed range of the motor, while also improving efficiency under high-speed operating conditions. Originality/value The proposed NSPMSM can effectively increase power density and expand the motor’s speed regulation range.

Model predictive current control (MPCC), owing to its straightforward design and convenient multi-objective optimization, has been widely adopted in applications demanding high dynamic performance. However, the conventional MPCC suffers from poor current steady-state performance and severe parameter dependence. To address these issues, this paper proposes a virtual-vector based model-free predictive current control (MFPCC) scheme for permanent magnet synchronous machine (PMSM) drives with adaptive control-gain. The proposed approach is developed based on the ultra-local model (ULM) concept to simplify the control structure and enhance robustness. The disturbance is observed by a linear extended state observer (LESO) and the effect of control-gain deviation on disturbance observation is analyzed. In addition, a control gain adaptive method is introduced to weaken the high-frequency components of the integrated disturbance, which can further improve the performance of observer. Furthermore, the virtual-vector control set is built where symmetrical vector sequences are included to reduce torque ripple. An improved optimization strategy is also developed that reduces computation and improves steady-state performance. Comprehensive experimental results confirm the effectiveness and superiority of the proposed method in terms of steady-state performance, robustness, and computational burden.

The grid-forming (GFM) wind turbine with energy storage is regarded as a promising solution for the integration of renewable energy sources (RESs) into power systems. However, the system faces the risk of instability during large grid disturbances, such as grid voltage sags and frequency variations. To address this issue, this paper proposes a coordinated control method to enhance the transient stability of GFM wind turbines with energy storage. First, a permanent magnet synchronous generator (PMSG)-based wind turbine employing grid-forming control and integrated with an energy storage system is introduced. Then, transient stability cases are identified based on the equal area criterion (EAC) within the virtual synchronous generator (VSG) control framework. On this basis, a low-voltage ride-through (LVRT) method is developed by coordinately adjusting inertia, damping, and active power reference according to fault severity, thereby ensuring system stability under low-voltage grid fault. Furthermore, a frequency fluctuation mitigation (FFM) is proposed to suppress power oscillations under frequency disturbances. The coordinated LVRT and FFM methods enable effective stabilization of the system under grid voltage and frequency faults. Finally, simulation results validate the theoretical analysis and demonstrate the effectiveness of the proposed control strategy.

The dual-channel permanent magnet synchronous motor (PMSM) processes advantages of high torque density, strong fault tolerance and high-power level. Nonetheless, the control quality is seriously restricted owing to the current harmonics and computation complexity, deriving from inevitably unbalanced power supplies and multi-dimension of voltage vectors. To this end, an improved space vector modulation (SVM) strategy is proposed in this paper. At first, to adapt the dual-power supplied system, the ratio of dc-links is included in the synthesized results, and subsequently the synthesized voltage vectors can be constructed with elaborate magnitudes and angles. Thereafter, the modified selection criterion is introduced from the aspect of suppressing current harmonics without additional calculation burden. Meanwhile, the undistorted saddle-shaped modulation waveforms are available to deal with the unbalanced supplies condition. In this sense, the harmonics and torque fluctuation are further optimized. Finally, experimental results prove that the improved SVM has a superior steady-state performance, equipping with quite low current harmonic distortion and intact saddle-shaped modulation waveforms.

Variable flux memory machine (VFMM) is recognized as a competitive counterpart to traditional permanent magnet synchronous machine (PMSM) for electrified transportation, due to the advantages in terms of extended speed range and improved global efficiency. Regarding the control aspect of VFMM drives, the most crucial challenge refers to the design of current controller with emphasis on the exclusive magnetization state (MS) manipulation, which is realized via short d-axis current pulse injection. This article proposes an improved finite-control-set model-free predictive current control (FCS-MFPCC) for VFMM drives. In order to ensure simultaneously the dq-axis current tracking performances during MS manipulating processes, a novel hybrid optimization algorithm is proposed. In particular, a sliding mode-based regulation dedicated to the q-axis current is additionally designed in the proposed algorithm, and by doing so, it is guaranteed that the q-axis current is regulated toward its reference. Finally, experiments on a VFMM test rig are conducted to validate the effectiveness and superiority of the proposed FCS-MFPCC method.

Hybrid wind-wave energy system, integrating floating offshore wind turbine and wave energy converters, has received much attention in recent years due to its potential benefit in increasing the power harvest density and reducing the levelized cost of electricity. Apart from the design complexities of the hybrid wind-wave energy systems, their energy conversion efficiency, power output smoothness and their safe operations introduce new challenges for their control system designs. Recent studies show that advanced model-based control strategies have the great potential to significantly improve their overall control performance. However the performance of these advanced control strategies rely on the computationally efficient control-oriented models with sufficient fidelity, which are normally difficult to derive due to the complexity of the hydro-, aero-dynamic effects and the couplings.In most available results, the hybrid wind-wave energy system models are established by using the Boundary Element Method, devoting to understanding the hydrodynamic responses and performance analysis. However, such models are complex and involved relatively heavy computational burden, which cannot be directly used for the advanced model-based control methods that are essential for improving power capture efficiency from implementing in practice. To overcome this issue, this paper proposes a control-oriented model of the hybrid windwave energy system with six degrees of freedom. First, ...

ABSTRACT Although the model predictive control (MPC) with discrete space vector modulation (DSVM) can effectively mitigate current ripple, thus reducing torque ripple, the computational burden increases dramatically with candidate voltage vectors. In this paper, a light‐computational MPC with current enhancement for permanent magnet synchronous machines based on DSVM is proposed, aiming to decrease the computational complexity and further improve the performance of the MPC with DSVM. Different from the existing DSVM, the proposed DSVM synthesizes virtual voltage vectors using only four real voltage vectors. In addition, it is noteworthy that the duty cycles of three nonzero voltage vectors corresponding to the virtual voltage vector are also duty cycles of the inverter upper bridge arms, thus eliminating the inverter switching signal calculation. Based on the proposed DSVM strategy, a voltage vector preselection method is designed to reduce candidate voltage vectors by four. Thereafter, voltage vectors around the optimal voltage vector are extended to further enhance current performance. Experiments are conducted on a 2‐kW electric drive platform to verify the feasibility and effectiveness of the proposed method.