This paper enhances the control performance of deadbeat predictive speed control (DPSC) by employing disturbance torque observer. First, mechanical model of the PMSM and DPSC control block diagram are established. Subsequently, the mechanical model is simplified by consolidating disturbances into disturbance torque. Extended state observer (ESO) is established to observe this disturbance torque, followed by stability analysis. Addressing the limitations of ESO, quasi-resonant (QR) ESO (QRESO) is developed by integrating ESO with QR. Bode plot analysis is employed to examine the influence of each parameter on QR. Finally, experiments are given to validate that QRESO enhances the dynamic response speed of PMSM control and suppresses ripples at specified frequencies.

In this article, the influence of resistance on the discrete-time modeling is investigated for position sensorless control of long-cable permanent magnet synchronous motor (PMSM) drives with low switching frequencies. Specifically, a discrete-time model of PMSM is proposed based on the segmented pulsewidth modulation voltages, with which the discretization accuracy is increased effectively compared with the conventional average-voltage model for the long-cable drive, usually with distinct resistance. The index of normalized carrier frequency is defined to assess the influence of resistance on the discrete-time modeling accuracy. Accordingly, the methods of discretization and application to position observation are presented with the proposed segmented-voltage discrete-time model. Experimental results are given to verify that improved discretization accuracy and position observation performance can be provided for the long-cable PMSM drives with low switching frequencies using the proposed model.

In this article, the carrier-frequency square-wave voltage injection based position sensorless control is proposed for cascaded H-bridge (CHB) converter fed interior permanent-magnet synchronous motor drives. The carrier frequency of CHB topology is usually several hundred hertz to limit switching losses. It is challenging for implementing the high frequency (HF) signal injection for CHB converter using carrier-phase-shift pulsewidth modulation (CPS-PWM). For addressing that issue, the carrier-frequency injection methods, i.e., the preliminary injection and the advanced injection methods are proposed. In particular, the advanced injection based method employs a single H-bridge to generate the HF voltage injection signals separately, while other H-bridge modules modulate the controller voltage references with CPS-PWM modulation. Consequently, the modulation of HF voltages and controller references is decoupled, and the injection frequency can be increased up to the switching frequency (carrier frequency). In addition, a moving average filter with window length equaling the ratio of sampling frequency to injection frequency is proposed for position signal extraction, in such a way that the disturbances caused by harmonics in square-wave voltages can be eliminated, which fully utilizes the higher sampling frequency characteristic of CHB converter fed PMSM drives. Experiments are conducted to verify effectiveness of the proposed carrier-frequency injection based position sensorless control method.

The three-phase four-leg (TPFL) inverter fed motor drive has an additional phase leg, which can provide the redundant current path under fault conditions. Therefore, the TPFL inverter fed motor drive has attracted wide attention for applications with high reliability. To minimize the adverse impacts of diagnosis, i.e., misdiagnosis and torque disturbance, a diagnosis-free self-tolerant scheme is proposed for TPFL fed permanent magnet synchronous motor (PMSM) drives with open-circuit faults. It is revealed that the conflicts between d/q-axis current controllers and zero-sequence current controller cause the torque ripple in TPFL inverter fed PMSM drives under faults. For addressing that issue, a notch filter at the characteristic frequency is designed in zero-sequence current control path, and proper periodic current controllers are dedicated to achieve compatibility between normal and faulty operating conditions. Thus, the self-tolerant operation can be realized without diagnosis or reconfiguration of current references. Experimental results are given to verify the effectiveness of the proposed diagnosis-free self-tolerant scheme for TPFL inverter fed PMSM drives with both open-phase and open-switch faults.

The dual three-phase PMSM (DTP-PMSM) drives have received wide attention at high-power high-efficiency applications due to their merits of high output current ability and copper-loss-free field excitation. Meanwhile, the DTP- PMSM drive provides higher fault-tolerant capability for high- reliability applications, e.g., pumps and actuators in aircraft. For high-power drives with limited switching frequencies and highspeed drives with large fundamental frequencies, the ratio of switching frequency to fundamental frequency, i.e., the carrier ratio, is usually below 15, which would significantly degrade the control performance. The purpose of this paper is to review the recent work on the modulation and control schemes for improving the operation performance of DTP-PMSM drives with low carrier ratios. Specifically, three categories of methods, i.e., the space vector modulation based control, the model predictive control (MPC), and the optimized pulse pattern (OPP) based control are reviewed with principles and performance. In addition, brief discussions regarding the comparison and future trends are presented for low-carrier-ratio (LCR) modulation and control schemes of DTP-PMSM drives.

Deadbeat predictive current control (DPCC) is widely adopted in permanent-magnet synchronous motor (PMSM) control systems owing to its merits including fast dynamic response, high steady-state accuracy, and elimination of complex parameter tuning procedures. Considering the critical dependency of DPCC on model accuracy and the oversight of eddy current reaction in conventional PMSM modeling, this paper extends the vector magnetic circuit (VMC) -based PMSM model and DPCC strategy by proposing a novel generalized proportion-integral observer (GPIO) with its discrete-time implementation and parameter design guidelines. Simulation results indicate that the VMC-model-based DPCC demonstrates enhanced current regulation precision, reduced settling time, and reduced current prediction error compared to conventional DPCC, under identical disturbance and observer conditions. From the perspective of disturbance observation and compensation performance, the enhanced DPCC performance by incorporating the eddy current reaction in the VMC-PMSM model has been verified.

In this article, a Luenberger observer discretized by a hybrid method for interior permanent magnet synchronous machine (IPMSM) sensorless drives is proposed. It owns high discretization accuracy and is easy to implement in digital control systems, enabling it to be applied to low sampling-to-fundamental frequency ratio (SFR) high speed motor drives. First, the conventional discretization methods are investigated. Then, the hybrid method combining forward Euler (FE) method and fourth-order Runge-Kutta (RK-4) method is presented. All the methods are evaluated from two aspects: discretization error and computational cost. After that, the design of the proposed Luenberger observer is introduced. Finally, simulation results are given to validate the proposed scheme.

This paper proposes a high-frequency (HF) square-wave voltage injection method to identify the parameters for three-phase permanent-magnet synchronous motor (PMSM) drives fed by cascaded H-bridge (CHB) inverters. The key is to identify the $dq-\text{axis}$ inductances independently. In the proposed method, the one module of each phase in the CHB inverter is specifically configured to inject HF square-wave voltages, while the remaining modules are maintained for reference voltage modulation. Furthermore, effective compensation measures are implemented to address the harmonic issues arising from the injection of HF square-wave voltages, the amplitude attenuation caused by filters, and the impact of the inherent nonlinear characteristics of CHB inverters on parameter identification. Simulation results are given to validate effectiveness of the proposed parameter identification method.

Model predictive pulse pattern cotrol (MP3C) is an effective control method with low switching frequencies. Its dynamic performance is affected by the length of the predictive horizon. Although a short predictive horizon will bring fast transient responses, it will also be delayed sometimes because of the lack of adjustable switching angles within the predictive horizon. This paper proposes an improved scheme with additional pulse insertion during the transient process for dual three-phase permanent-magnet synchronous motor (DTP-PMSM) drives, which achieves faster transient responses with no impact on the steady-state performance. Firstly, The insertion conditions are analysed in detail. Further, the calculation method of the width of inserted pulses is proposed. At the end, both the simulation results of the standard MP3C and the improved MP3C are presented to verify the validity of proposed scheme.

The utilization of silicon (Si) insulated gate bipolar transistors (IGBTs) and silicon carbide (SiC) MOSFETs in hybrid three-level active neutral-point-clamped (3L-ANPC) inverter inherits the advantages of traditional 3L-ANPC inverter, which has the capacity of balanced loss distribution and fault-tolerant operation. In addition, the improvement of short-circuit withstanding capacity and the tradeoff between cost and efficiency can be achieved in hybrid 3L-ANPC inverter. In this paper, an improved Si/SiC hybrid 3L-ANPC inverter is proposed to achieve balanced thermal distribution among power devices. A snubber branch is added in the topology to minimize parasitic inductance and address resonant issues. Based on available commutation types, two modulation schemes are analyzed to regulate current paths and power loss distribution. Furthermore, a simulation based on a hybrid 3L-ANPC inverter is provided to validate the effectiveness of the theoretical analysis and compare thermal distributions of different modulation schemes. Simulation results show that appropriate selection of modulation strategies helps improve system reliability.

In this paper, multiple advanced low-switching-frequency modulation and control schemes are investigated for dual three-phase permanent-magnet synchronous motor (PMSM) drives. The modulation schemes under investigation include multisampling space vector modulation (MS-SVM), selective harmonic elimination pulse width modulation (SHEPWM) and synchronous optimal pulse width modulation (SOPWM) while the control schemes include complex vector control, model predictive control (MPC) and flux trajectory control-based model predictive pulse pattern control (MP 3 C). The difference between three-phase and dual three-phase PMSM drives at low switching frequencies is analyzed. Moreover, an optimal pulse width modulation (PWM)-based MP 3 C scheme is proposed for the dual three-phase PMSM, where the optimal PWM modulation and MP 3 C control are combined such that the optimal steady-state and dynamic control performance is achieved among the modulation and control schemes investigated. Experimental results are given to compare and validate the proposed control scheme.

In this article, the phenomena of switching surges due to eddy-current reaction are investigated and analyzed for permanent-magnet synchronous motor (PMSM) drives. With vector magnetic circuit (VMC) theory, a new three-phase PMSM model is proposed, where the differential terms of stator voltages are included for considering the transient eddy-current reaction. In this way, the cause of switching surges in PMSM drives is revealed to be the switching actions of power devices in power converters. Furthermore, the switching surges have been evaluated quantitatively by modeling the eddy-current reaction by a transient magnetic coefficient in the magnetic circuit, and the impact factors have been analyzed. The model predictive control (MPC) scheme is employed as an application case for evaluating the proposed PMSM model considering switching surges. Experimental results have been given to verify that the proposed modeling method can present improved current prediction accuracy and control performance at various conditions than the existing methods even when the disturbance observer is employed.

In this article, the position sensorless control with high-frequency (HF) square-wave voltage injection is investigated for cascaded H-bridge (CHB) converter fed three-phase permanent-magnet synchronous motor (PMSM) drives. A collaborative HF signal injection method is proposed for CHB topology to decouple frequencies of the injected HF signals and the carrier. In each phase of the CHB converter, a single H-bridge is configured to inject the square-wave voltage while the others are configured for the modulation of reference voltages. Therefore, the frequency of the orthogonal square wave can be equal to or higher than that of the carrier and thus the position estimation performance is improved. Moreover, a cumulative signal processing method is proposed to eliminate the influence of square wave harmonics. Simulation verification has been conducted to validate the effectiveness of the proposed sensorless control scheme.

The magnetic circuit theory stands as a pivotal theory for electromagnetic devices like electrical machines and transformers,furnishing indispensable tools for addressing intricate electromagnetic challenges and optimizing the performance of electromagnetic apparatus.In this paper,the historical development of magnetic circuit theory is first traced,providing insights into the valuable contributions made by earlier researchers towards refining magnetic circuit theories,including magnetic circuit parameters and their respective theoretical development.Additionally,their limitations and the challenges they encounter in practical applications are analyzed.On this basis,this paper pioneers the definition of magductance and hysteretance from the fundamental physical properties of magnetic circuit,establishes the vector magnetic circuit theory encompassing three core components(reluctance,magductance,and hysteretance),systematically and completely characterizes the three basic properties of magnetization,eddy current and hysteresis in the magnetic circuit,reveals the intrinsic connection between the virtual magnetic power and the electric power,and puts forward the magnetoelectric power law.An exhaustive comparative analysis with other magnetic circuit theories or modeling methods is conducted to illustrate their interconnections and differences.In order to show the applicative value of the vector magnetic circuit theory in science and engineering,four practical application scenarios are presented.Finally,the unique features of the proposed vector magnetic circuit theory are highlighted and the future research directions are prospected.

In this article, a new model has been derived for the three-phase permanent magnet synchronous motor (PMSM) considering the eddy-current reaction by using the vector magnetic circuit (VMC) theory. The eddy-current reaction in the stator core is described by a magnetic component, i.e., magnetic-inductance (magductance) in the magnetic circuit of PMSM. Consequently, the stator flux linkage equation is calculated by the VMC and thus the stator voltage equation considering the eddy-current reaction is established. The proposed VMC-based modeling method offers a clear derivation of eddy-current reaction effect and a more accurate calculation of stator flux linkage for the modeling of PMSM. Thus, concise dynamic voltage equations can be available for improving the predictive control of PMSM. The deadbeat predictive current control (DPCC) and trajectory extrapolated model predictive control (MPC) schemes are selected as typical application cases to verify the effectiveness of the proposed VMC-based PMSM model. Experimental results have been given to verify that the prediction accuracy of stator current is increased and the performance of DPCC and MPC is improved with the proposed VMC-based PMSM model.

In this paper, the modeling and mitigation method of torque ripple are investigated for permanent-magnet synchronous motor (PMSM). A new torque ripple model is proposed for three-phase PMSM based on general airgap field modulation theory. The mapping relationship between the torque order and the current order has been revealed. The qualitative and quantitative relationship between the stator harmonic current and torque ripple is established directly without other intermediate variables. The phase and amplitude of the torque component are found to be proportional to the phase and amplitude of the injected harmonic current. Therefore, only a few constant coefficients are required by finite element analysis (FEA) simulation. With the proposed torque model, directional mitigation of torque ripple can be realized by harmonic current injection method with low computational burden by FEA. Repetitive control is employed for harmonic current injection. FEA simulation and experimental results at different operating conditions verify the validity of the proposed torque model and ripple mitigation method.

Dual three-phase permanent-magnet synchronous motors (PMSMs) are becoming more popular in safety-critical applications such as aircraft system and electric vehicles, primarily due to their robust fault-tolerant capabilities. Recently, natural fault-tolerant control methods have drawn attentions for their abilities to avoid the complexities of control structure reconfiguration, fault diagnosis, and current reference adjustments. However, the post-fault performances, particularly regarding the stator copper loss and the current amplitude, have remained uncertain or uncontrolled in most of reconfigurationless control methods. Aiming to fill this gap, the post-fault strategy has been investigated for dual three-phase PMSM with single open-phase fault with universal control structure. It is revealed that the post-fault performance under open-phase fault can be determined by the positive-sequence current in harmonic subspace. The amplitude model of each phase current has been established as a function of the current amplitude ratio and the phase shift between dual three-phase windings. On this basis, the maximum torque (MT) can be achieved by the universal control method under post-fault condition. The experimental results are presented to illustrate the effectiveness of the proposed method.

Aiming at mitigating the torque ripple at low-carrier-ratio operating conditions, an optimal pulsewidth modulation (PWM) scheme is proposed for the dual three-phase permanent-magnet synchronous motor (DTP-PMSM). The current trajectory induced by inverter harmonic voltages on the torque subspace is derived and the model of torque ripple is established. Then, the switching angles are optimized offline to mitigate the torque ripple directly while limiting the current harmonics simultaneously. It is revealed that the torque ripple is influenced by torque angle in addition to the voltage harmonics. Moreover, the differences between the optimal switching angles for torque ripple and those for current harmonics in DTP-PMSM are analyzed. To achieve the closed-loop control performance, the proposed optimal PWM strategy is applied to the model predictive pulse pattern control (MP 3 C) scheme. The experimental results are given to verify the validity of the proposed optimal PWM-based MP 3 C scheme.

Dual three-phase interior permanent-magnet synchronous motor (IPMSM) drives have received more attention by the merits of better fault-tolerant capability and lower torque ripples. To improve the reliability of the system against failures in position sensor, it is necessary to investigate the position estimation method for dual three-phase IPMSM drives. The high-frequency (HF) signals injection is utilized for position estimation in three-phase IPMSM drives during low-speed operation region. However, the torque ripples are inevitable owing to the mixing of fundamental and HF components in the same control space for three-phase IPMSM drives. In this article, the position sensorless control method has been proposed by injecting HF square-wave voltage in the harmonic subspace for the dual three-phase IPMSM drives. Since the harmonic subspace is decoupled from the torque subspace, the torque disturbance can be mitigated well with the proposed HF signal injection-based position sensorless method. Moreover, the digital filters in signal extraction and current feedback can be avoided and the signal separation process becomes easy with the proposed method. The experiments have been conducted to validate the performance of the proposed method.

In this article, switching strategies for dc-link current and voltage ripple reduction have been studied. The considered topology is a neutral-point clamped three-level (NPC-3L) inverter feeding a dual three-phase permanent-magnet synchronous motor (PMSM). The mechanisms of dc-link current and voltage ripple generation in an NPC-3L inverter-fed PMSM drive are analyzed in detail. Then, a two-step collaborative switching strategy is proposed, where the optimum switching sequences, including opposite small vectors, are applied in the two inverters collaboratively. Furthermore, the switching vectors of two inverters are rearranged in the sequence of their corresponding dc-link capacitor currents so that the overlapping of their peaks is avoided. Consequently, both the voltage ripple and current ripple in the dc-link capacitors are mitigated with the proposed two-step collaborative switching strategy. For the midpoint voltage of the NPC-3L inverter, the amplitude of fluctuation is reduced under low modulation index operation, while the high-frequency harmonic components are mitigated under high modulation index operation. The experimental results are given to verify the validity of the theoretical analysis and the proposed switching strategy.