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Wireless power transfer system has played an important role in rail transit, industrial production, and daily life. This article proposes a wireless power transfer permanent-magnet synchronous motor (WPT-PMSM) drive system based on the matrix converter (MC). The direct conversion of low-frequency ac and high-frequency ac is realized without dc link by using MC. The dual LCC compensation network is designed for better performance. In addition, a new control method has been proposed for the proposed WPT-PMSM drive to operate stably. In particular, the bidirectional power flow is achieved with the proposed WTP-PMSM drive and related control scheme. Through the mathematical modeling, the coordinated control of power converters on both sides of the coupling coil is achieved and the reactive power of the LCC compensation network is eliminated. The experiments on a 1 kW and 85 kHz laboratory prototype of the WPT-PMSM drive are presented to verify the feasibility and effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

In this article, a robust cascaded deadbeat predictive speed control method (PSC) is proposed with speed and disturbance observer for the dual three-phase variable-flux permanent-magnet synchronous motor (VF-PMSM) drives. Considering the intrinsic delay in speed loop, an improved predictive speed model has been derived in discrete domain. In turn, a speed observer is proposed for the cascaded PSC to mitigate the issue of this intrinsic delay. In order to improve the system robustness, the torque disturbance observer including the generalized proportional integral observer and the sliding-mode observer has been proposed for parameter variation and load torque perturbation. Furthermore, the stability analysis indicates that the margin of parameter mismatch is determined by the coefficient in the speed observer, which can be expressed as the equivalent gain in discrete domain. The performance comparison between the conventional PSC method and the proposed PSC method has been investigated for parameter robustness. The experimental results are presented to verify the improvements of the proposed PSC method for the dual three-phase VF-PMSM drives under model uncertainty and magnetization manipulation conditions. [ABSTRACT FROM AUTHOR]

The fault-tolerant control method of dual three-phase permanent-magnet synchronous motor (PMSM) drives has gained more and more attention in some applications, such as aircraft system and offshore wind energy system. In this letter, the reason for the torque ripple caused by the standard control method has been investigated in view of the frequency domain after the occurrence of a single open-phase fault. Based on the theoretical analysis, a universal control scheme has been proposed for the dual three-phase PMSM drives with two isolated neutral points, which can be implemented under either healthy condition or fault condition. The key is to modify with a closed-loop controller on harmonic subspace with the notch filter. The proposed method not only realizes the seamless transition between two operation conditions without fault diagnosis but also avoids the reconfiguration of the control structure. Moreover, the system optimization of the minimum copper loss under postfault condition has been integrated into the proposed method. The experimental results are presented to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this article, the control strategy is studied for the neutral-point-clamped three-level inverter-fed dual three-phase permanent-magnet synchronous motor (PMSM) drive with low switching frequencies. An interleaved finite-control-set model predictive control (MPC) scheme is proposed, where a two-layer MPC is designed to solve the multiobjective optimization problem. The two sets of windings in PMSM are sampled and controlled in an interleaved way so that the control delay and the prediction horizon of the drive system are reduced by half. Moreover, the proposed interleaved control scheme increases the equivalent sampling and control frequency from the perspective of the whole drive system, and thus provides better steady-state performance and dynamic performance. With the switching states of one inverter remaining unchanged, the cross traversal of vector candidate sets between two sets of windings is avoided, and the computational burden can be reduced effectively. Experimental results are given to verify the validity and effectiveness of the proposed interleaved control scheme. [ABSTRACT FROM AUTHOR]

The rotor flux linkage of permanent-magnet synchronous motor (PMSM) is of great importance for monitoring and high-performance control. However, most of the existing online estimation methods need prior knowledge of other PMSM parameters such as stator resistance and dq axis inductance, which are difficult to realize in the rank-deficient models of electrical machines. This article proposes a simple online estimation method of rotor flux linkage for the dual three-phase surface-mounted PMSM (SPMSM) drives with the assistance of injected position offset. The independent estimation model has been developed for the rotor flux linkage by appropriate setting of positon offset between two sets of three-phase windings of dual three-phase SPMSM drives. The proposed method not only has little influence on the output torque and high signal-to-noise ratio for observation, but also offers the superior performance in estimation accuracy irrespective of the influence of VSI nonlinearity. In addition, the proposed position-offset-based method is suitable for the full-speed region including the field-weakening operation. Finally, comprehensive experimental results are presented to verify validity of the proposed method under different working conditions. [ABSTRACT FROM AUTHOR]

A standard three-phase motor drive means a typical two-level voltage source inverter fed three-phase motor drive without any auxiliary circuits. Without fault-tolerant control, common open-circuit faults will cause the breakdown of the standard three-phase motor drives. Although the torque pulsation is theoretically inevitable under the open-circuit faults of standard three-phase motor drives, it's still meaningful to improve the fault-tolerant capability of standard three-phase drives to prolong the reliable operation. In this article, a current optimization based fault-tolerant control is proposed to minimize the proportion of torque loss for standard three-phase permanent-magnet synchronous motor (PMSM) drives under open-phase fault and open-switch fault conditions. Firstly, a two-mode current control is designed to minimize the proportion of torque loss without changing the mathematical model of the faulty motor. Secondly, a three-mode current control is proposed and combined with adjustment of pulse width to tolerate the open-switch faults. Instead of removing the faulty inverter leg directly, the remaining healthy switch in the faulty inverter leg is still utilized. In this way, the damage from torque pulsation can be relieved in the aspect of both frequency and intensity. Finally, the validity of the proposed fault-tolerant control is verified by experiments. [ABSTRACT FROM AUTHOR]

The silicon carbide (SiC) devices have attracted more and more attention due to the capability of withstanding higher blocking voltage, higher switching frequency, and higher temperature. However, challenges for SiC devices applied in voltage-source-inverter fed motor drives such as electromagnetic interference (EMI) issues and limited over-current capability still limit the further application of SiC devices. In this article, a novel SiC devices based zero-voltage-switching (ZVS) current-source-inverter (CSI) is proposed for permanent-magnet synchronous motor (PMSM) drive. The key is to propose an auxiliary resonant circuit, which achieves ZVS conditions for all switches in power circuits and reduces the dv/dt of high speed SiC devices. The resonant capacitor in the auxiliary circuit can clamp overvoltage caused by possible open-circuit faults. To further reduce the EMI, the random switching frequency pulsewidth modulation is designed for the proposed CSI motor drive. The system configuration, working principle, circuit design, and control schemes are described in detail. Both simulations and experiments are presented to verify the effectiveness of the proposed ZVS-CSI fed PMSM drive system. [ABSTRACT FROM AUTHOR]

In this article, a composite torque regulator is proposed for optimizing the torque tracking performance in direct torque-controlled permanent-magnet synchronous motor drives. In the proposed composite torque regulator, two new variable hysteresis bands are designed and combined with two constant hysteresis bands. In the conventional direct torque control (DTC) scheme, the torque increasing rate and decreasing rate are changed with different speeds and loads. Thus, the average torque will deviate the reference torque seriously under some operation states. With torque deviation, the reference torque can hardly reflect the actual electromagnetic torque, and the torque tracking becomes more difficult and unsatisfactory in dynamic process. On the other hand, the time delay of one sampling period further deteriorates the precision of torque tracking. By introducing the proposed composite torque regulator, both torque deviation and the impact of time delay on the torque ripple can be eliminated. In addition, the advantages of the conventional DTC scheme, namely low switching frequency, fast dynamic response, simple structure, and independence of motor parameters, can be reserved in the proposed DTC scheme with a composite torque regulator. Experimental results are presented to verify the effectiveness of the proposed scheme and compare its performance with the conventional DTC scheme. [ABSTRACT FROM AUTHOR]

Aiming at tolerating common electric faults of multiphase motor drives comprehensively and minimizing the adverse impacts from the remedial scheme itself, a diagnosis-free self-healing scheme is put forward for the open-circuit faults of dual three-phase permanent-magnet synchronous motor (PMSM) drives. First, the self-healing mechanisms of dual three-phase PMSM drives are analyzed in detail. On the basis of theoretical analysis, the repressed self-healing capability of the dual three-phase PMSM drives is fully released by optimizing the current references on harmonic subspace. Since the diagnosis process is not required in the proposed self-healing scheme, the misdiagnosis problem and the prolonged damage caused by the additional time cost of diagnosis can be fundamentally avoided. The proposed self-healing scheme can be generally applied to open-switch faults, single open-phase faults, and multiple open-phase faults in the multiphase motor drives. No change is required for the machine model, modulation strategy, or control framework under different open-circuit faults. Thus, the complex transition strategies among different fault-tolerant control methods for different faults can be avoided, and the adverse impacts from the remedial scheme itself can be minimized. Experimental verification is presented to prove the validity of the proposed self-healing scheme. [ABSTRACT FROM AUTHOR]

In this article, the switching strategy and the remedial control scheme are studied for the cascaded current-source converters (CSCs) fed dual three-phase permanent-magnet synchronous motor (PMSM) variable-speed drives. An optimized space vector modulation (SVM) strategy is proposed to reduce the DC-link current ripple for the proposed drives system. In particular, this switching strategy can work effectively for motor drives under low speed with low back EMF, where there exists a large voltage difference between peak voltage values on the grid side and the motor side. Apart from that, a hybrid fault-tolerant control scheme is also designed for the open-phase fault in dual three-phase PMSM drives system, aiming at achieving small DC-link current ripple and torque ripple, low copper loss, and machine-friendly waveform quality. With the proposed optimized SVM and the hybrid fault-tolerant control strategy, the DC-link current ripple of the cascaded CSCs system can be effectively reduced and good operational performance can be obtained under both normal operation condition and open-phase fault condition. Experimental results are provided to verify the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

This paper proposes a novel nonlinear optimization-based sensorless control scheme for surface-mounted permanent magnet synchronous motors (SPMSM) over wide speed range operations. Two algebraic constraints derived from the voltage equations and the flux equations of the SPMSM system are fundamental to the establishment of the proposed scheme. The position estimation algorithm generates the rotor position estimate via the stator flux estimates obtained by minimizing an equality constrained scalar function. Specifically, the flux information is extracted both from the voltage-based flux model and the current-based flux model, which contributes to its robustness against the inherent weakness of the pure integrator to dc offsets. Meanwhile, a nonlinear observer, based on the standard gradient search, is constructed for speed estimation. The proposed method is unique because the position estimation and the speed estimation are achieved independently; thus, the complexity associated with the speed dependence in position estimation is eliminated. Further, it is simple to implement. The feasibility and effectiveness of the proposed position algorithm and the speed observer have been verified by experiments under different operating conditions. [ABSTRACT FROM AUTHOR]

In this paper, fault diagnosis and fault-tolerant control strategies have been studied comprehensively for dual three-phase permanent-magnet synchronous motor (PMSM) drives to improve the reliability. Based on direct torque control (DTC) with space vector modulation, a series of diagnostic and tolerant control methods have been proposed for five types of faults, namely, speed-sensor fault, dc-link voltage-sensor fault, current-sensor fault, open-phase fault, and open-switch fault. First, diagnosis and tolerant schemes are proposed for speed-sensor fault by estimating the rotor angle speed with the rotating speed of stator flux. Second, diagnosis and tolerant schemes are proposed for dc-link voltage-sensor fault by combining the current model based stator flux observer with the voltage model based stator flux observer. Third, a three-step method is designed to diagnose three types of faults related to current signals, namely, current-sensor fault, open-phase fault, and open-switch fault simultaneously. A vector space decomposition based current estimation method is proposed to achieve fault-tolerant control for the current-sensor fault, and the voltage compensation based fault-tolerant control is presented for both open-phase and open-switch faults. The experiments have been taken on a laboratory prototype to verify the effectiveness of the proposed fault diagnosis and fault-tolerant schemes. [ABSTRACT FROM AUTHOR]

This paper proposes a self-adaption Kalman observer (SAKO) used in a permanent-magnet synchronous motor (PMSM) servo system. The proposed SAKO can make up measurement noise of the absolute encoder with limited resolution ratio and avoid differentiating process and filter delay of the traditional speed measuring methods. To be different from the traditional Kalman observer, the proposed observer updates the gain matrix by calculating the measurement noise at the current time. The variable gain matrix is used to estimate and correct the observed position, speed, and load torque to solve the problem that the motor speed calculated by the traditional methods is prone to large speed error and time delay when PMSM runs at low speeds. The state variables observed by the proposed observer are used as the speed feedback signals and compensation signal of the load torque disturbance in PMSM servo system. The simulations and experiments prove that the SAKO can observe speed and load torque precisely and timely and that the feedforward and feedback control system of PMSM can improve the speed tracking ability. [ABSTRACT FROM PUBLISHER]

The paper proposes the design of a sensorless control for driving a permanent magnet synchronous motor (PMSM). The drive is fed by a current source inverter (CSI) which adopts the paralleled configuration to increase the power level. The key is to design the interleaved operation and active damping to suppress the LC resonance and reduce the low order harmonics for motor voltages and currents. Thus, the better voltage and current waveforms could provide good performance for the extended Kalman filter (EKF) to estimate the PMSM rotor position. The proposed control scheme is designed, analyzed and compared with other methods available. It has been verified that the proposed drive system can offer good operating performance by computer simulation. [ABSTRACT FROM PUBLISHER]

In this paper, a current-source-converter (CSC)-based high-power high-speed (HPHS) permanent-magnet synchronous motor drive is proposed for high-speed compressor applications. The most important feature of the proposed CSC-fed HPHS drive is that the switching frequency is limited to 420 Hz at 200-Hz fundamental frequency. In the drive system, the whole operation range is divided into three regions, namely, the high-, medium-, and low-speed regions, where different modulation strategies and control schemes are used with the requirement of switching frequency and output filter. In particular, a two-pulse space vector modulation with dynamic capacitor voltage control is proposed for the high-speed region to achieve better dynamic and harmonic performance. Both simulation and experiments verify the proposed control strategy. [ABSTRACT FROM PUBLISHER]

In this article, a coupled fault-tolerant control (C-FTC) is proposed for primary permanent-magnet linear motor traction system in subway applications. By coupling the faulty mover with a healthy mover, the proposed C-FTC can achieve continuous operation of the faulty mover, in which one or more current sensors fail. A healthy mover is determined as the reference mover. The switch-states of the reference mover are also applied to its mathematical model. As a result, synchronous currents of the reference mover are also estimated from its mathematical model, and they are treated as the reference currents of the mathematical model of the faulty mover. Hence, the switch-states of the faulty mover can be determined. Therefore, the faulty mover can be controlled without any current sensors. The key of C-FTC is to compensate the parameter variations and the nonlinear effects of the faulty mover drive system with those of a healthy mover drive system, which is the main contribution of this article. Comparing with the conventional current-sensorless control, C-FTC has stronger robustness to the parameter variations and the nonlinear effects. The effectiveness and robustness of the proposed C-FTC are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a new phase current reconstruction scheme without using null switching states for interior permanent magnet synchronous motor (IPMSM) sensorless control. The phase currents are independently reconstructed and no additional test voltage pulses are required. First, the principle of the basic phase current reconstruction for IPMSM drive system is analyzed in detail. Then, an independent phase current reconstruction scheme without using null switching states is proposed. The current reconstruction dead zone is divided into six sectors, and each sector is split into three parts with corresponding vector synthesis methods. Meanwhile, the null switching states, V000 and V111, are removed from the proposed scheme. In this case, the zero vector is synthesized by the other available vectors. Finally, the reconstructed three-phase currents are utilized for high frequency sine-wave voltage injection-based position estimation. The effectiveness of the proposed scheme is verified by experimental results on a 5 kW IPMSM motor prototype, which shows that the reconstructed phase currents track the actual currents accurately under different working conditions. [ABSTRACT FROM PUBLISHER]

The end force of North-South permanent magnet linear synchronous motor (NS-PMLSM) fluctuates symmetrically with a period of one pole. Different from it, the end force's fluctuation cycle of the consequent-pole permanent magnet linear synchronous motor (CP-PMLSM) is usually two poles and asymmetrical. Especially, within two half cycles, the end force presents complex asymmetric characteristics. In this paper, a piecewise function model of the end force of CP-PMLSM is established. Then a primary segmented design method for adjusting the period, symmetry and phase of the end force waveform is proposed. The two-segment and grouped four-segment modular distances are combined and matched to eliminate the odd-numbered harmonics of the end force and suppress the thrust ripple. A slotless primary core experimental platform and a slotted CP-PMLSM prototype are manufactured and tested to verify the theoretical analysis and simulation results. [ABSTRACT FROM AUTHOR]