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Sensorless control of permanent magnet synchronous motor (PMSM) can increase the reliability of electric actuators of more electrical aircraft. Numerical online parameter estimation method will enhance the performance for sensorless control methods based on sliding mode observer (SMO). However, numerical online parameter identification methods typically assume zero rotor position estimation error to ensure full rank of the identification equation set. This assumption actually leads to errors in parameter identification, resulting in steady‐state errors in rotor position estimation. This paper focuses on a compensation method for PMSM online parameter identification that takes into account rotor position estimation error. This method is used for sensorless control based on SMO, using model reference adaptive systems for online parameter identification, and no additional parameter adjustment required. Validation is conducted on a PMSM experimental platform with maximum load of 15kW. The experimental results of 1000 r/min steady state operation proved the effectiveness of the method, and the dynamic experiments with 5 and 15kW loads proved that the method has no significant adverse effect on the system dynamics. [ABSTRACT FROM AUTHOR]

Abstract To address the problem of considerable current distortions in traditional single‐vector model predictive control (MPC) method for four‐switch three‐phase inverter (FSTPI)‐fed permanent magnet synchronous motor, a double‐vector MPC scheme has been studied. However, it still lacks a sufficient theoretical foundation, causing doubts about its effectiveness. To perfect this deficiency, a novel visualisation analysis scheme considering DC voltage pulsation is presented to demonstrate the validity of the traditional double‐vector MPC method for FSTPI. The analysis results reveal for the first time that the traditional double‐vector MPC method is not always superior to the single‐vector method as there is no zero voltage vector for FSTPI. So, a new virtual voltage vector is defined to compensate the deteriorated control performance caused by the absence of zero voltage vectors, based on which an improved double‐vector MPC method is further put forward to reduce the current ripples. Then, the presented visualisation analysis is adopted to demonstrate the validity of the improved MPC strategy under pulsating DC voltage conditions. Finally, a new voltage sector division technology is further put forward to simplify the implementation steps of the presented method. Contrastive experimental studies demonstrate the availability of the improved MPC strategy.

Abstract For the purpose of enhancing the performance of interior permanent magnet synchronous motors (IPMSMs) sensorless control, a flux observer based on a third‐order generalized integrator with enhanced frequency‐locked loop (TOGI‐EFLL) is introduced in this paper. Compared with the traditional second‐order generalized integrator with frequency‐locked loop (SOGI‐FLL), the proposed TOGI‐EFLL can effectively mitigate the direct current (DC) bias stemming from non‐ideal factors, such as the inverter non‐linearities and detection errors, without introducing additional parameters. Initially, the active flux observer model and the limitations of the conventional SOGI‐FLL are presented. Subsequently, the proposed flux observer based on TOGI‐EFLL has been intensively investigated. Furthermore, the design of the damping factor and the digital implementation of the algorithm are developed to ensure seamless integration into digital systems. Finally, the effectiveness of the proposed sensorless control strategy is validated through the comprehensive experimental results.

Abstract The realisation of fast position tracking control and strong robust control of the chain‐type rotary shell magazine in the complex systems such as the large calibre howitzer has been the focus and challenge of research. The predictive control strategies can achieve a fast dynamic response, but it relies on the system model. By integrating the generalised predictive control method with sliding mode theory, a novel robust generalised predictive position control method is proposed. Firstly, a non‐cascade position tracking controller is designed based on the continuous‐time model of the systems; then, a sliding mode compensation structure is introduced to address the degradation of control performance due to load variations and external disturbances. The scheme utilises the sliding mode switching term to overcome the effects caused by the disturbances while preserving the fast dynamic response characteristics of the original predictive control. Moreover, the disturbance observer is designed to further enhance the robustness by producing corresponding compensation according to the perturbation quantity. The proposed controller has been validated in a shell magazine test bench, indicating its superior position control performance of the shell magazine under different load conditions.

For the purpose of enhancing the performance of interior permanent magnet synchronous motors (IPMSMs) sensorless control, a flux observer based on a third‐order generalized integrator with enhanced frequency‐locked loop (TOGI‐EFLL) is introduced in this paper. Compared with the traditional second‐order generalized integrator with frequency‐locked loop (SOGI‐FLL), the proposed TOGI‐EFLL can effectively mitigate the direct current (DC) bias stemming from non‐ideal factors, such as the inverter non‐linearities and detection errors, without introducing additional parameters. Initially, the active flux observer model and the limitations of the conventional SOGI‐FLL are presented. Subsequently, the proposed flux observer based on TOGI‐EFLL has been intensively investigated. Furthermore, the design of the damping factor and the digital implementation of the algorithm are developed to ensure seamless integration into digital systems. Finally, the effectiveness of the proposed sensorless control strategy is validated through the comprehensive experimental results. [ABSTRACT FROM AUTHOR]

To address the problem of considerable current distortions in traditional single‐vector model predictive control (MPC) method for four‐switch three‐phase inverter (FSTPI)‐fed permanent magnet synchronous motor, a double‐vector MPC scheme has been studied. However, it still lacks a sufficient theoretical foundation, causing doubts about its effectiveness. To perfect this deficiency, a novel visualisation analysis scheme considering DC voltage pulsation is presented to demonstrate the validity of the traditional double‐vector MPC method for FSTPI. The analysis results reveal for the first time that the traditional double‐vector MPC method is not always superior to the single‐vector method as there is no zero voltage vector for FSTPI. So, a new virtual voltage vector is defined to compensate the deteriorated control performance caused by the absence of zero voltage vectors, based on which an improved double‐vector MPC method is further put forward to reduce the current ripples. Then, the presented visualisation analysis is adopted to demonstrate the validity of the improved MPC strategy under pulsating DC voltage conditions. Finally, a new voltage sector division technology is further put forward to simplify the implementation steps of the presented method. Contrastive experimental studies demonstrate the availability of the improved MPC strategy. [ABSTRACT FROM AUTHOR]

The realisation of fast position tracking control and strong robust control of the chain‐type rotary shell magazine in the complex systems such as the large calibre howitzer has been the focus and challenge of research. The predictive control strategies can achieve a fast dynamic response, but it relies on the system model. By integrating the generalised predictive control method with sliding mode theory, a novel robust generalised predictive position control method is proposed. Firstly, a non‐cascade position tracking controller is designed based on the continuous‐time model of the systems; then, a sliding mode compensation structure is introduced to address the degradation of control performance due to load variations and external disturbances. The scheme utilises the sliding mode switching term to overcome the effects caused by the disturbances while preserving the fast dynamic response characteristics of the original predictive control. Moreover, the disturbance observer is designed to further enhance the robustness by producing corresponding compensation according to the perturbation quantity. The proposed controller has been validated in a shell magazine test bench, indicating its superior position control performance of the shell magazine under different load conditions. [ABSTRACT FROM AUTHOR]

Abstract Model predictive current control (MPCC) has been widely recognized as a high‐performance scheme for permanent magnet synchronous motor drives because of its simple control structure. This article proposes a novel multivector MPCC (MMPCC) method based on a hybrid control set, which includes both original basic voltage vectors (VVs) and synthesized VVs. The two active VVs and one null VV are considered as an initial control set, and the exact combination of them depends on their corresponding durations, which are calculated by stator current slopes in dq frame with the use of the prediction formula. Contrary to the traditional cost function, an alternative hybrid control set can achieve superior voltage precision. This is due to the involved cost function that minimizes the maximum of prediction current errors, which typically occur at non‐integer sample instants during the control period. The performance of the proposed MMPCC method has been experimented to confirm its effectiveness, compared with the conventional MPCC (CMPCC) and duty‐cycle MPCC (DMPCC). The results indicated an anticipated enhancement in both dynamic and steady‐state performance at a low rotor speed, alongside a significant robustness against parameter mismatch.

Abstract The authors show a PM motor drive with the maximum speed of 170,000 r/min for a super‐high‐speed centrifugal air compressor, which is used in high‐altitude unmanned aerial vehicle (UAV). Conventional turbochargers used in high‐altitude UAV are usually driven by the exhaust of the engine in the fuel cell system; however, the exhaust is composed of vapour and water drop, which can't drive a mechanical turbocharger effectively. In this circumstance, a super‐high‐speed electric centrifugal compressor becomes attractive to boost the air pressure and improve overall efficiency. A wide‐speed‐adaptive sliding mode observer (WSA‐SMO) is adopted to realise the super‐high‐speed sensorless control. A super‐high‐speed motor drive system is developed based on the WSA‐SMO. The current waveform at 170,000 r/min is shown to prove the steady state performance. The acceleration curves and start/stop curves are shown to demonstrate the excellent dynamic performances.

Model predictive current control (MPCC) has been widely recognized as a high‐performance scheme for permanent magnet synchronous motor drives because of its simple control structure. This article proposes a novel multivector MPCC (MMPCC) method based on a hybrid control set, which includes both original basic voltage vectors (VVs) and synthesized VVs. The two active VVs and one null VV are considered as an initial control set, and the exact combination of them depends on their corresponding durations, which are calculated by stator current slopes in dq$dq$ frame with the use of the prediction formula. Contrary to the traditional cost function, an alternative hybrid control set can achieve superior voltage precision. This is due to the involved cost function that minimizes the maximum of prediction current errors, which typically occur at non‐integer sample instants during the control period. The performance of the proposed MMPCC method has been experimented to confirm its effectiveness, compared with the conventional MPCC (CMPCC) and duty‐cycle MPCC (DMPCC). The results indicated an anticipated enhancement in both dynamic and steady‐state performance at a low rotor speed, alongside a significant robustness against parameter mismatch. [ABSTRACT FROM AUTHOR]

The interior permanent magnet synchronous motor traction system of rail vehicles usually needs to run above base speed. It is necessary to implement high‐efficiency flux weakening control of the traction motor. This paper presents one single current regulation square wave strategy, which can improve the dynamic performance of the flux weakening control of the interior permanent magnet synchronous motor traction system. By proposing a novel switching criterion and the modulation method, smooth switching between the maximum torque per ampere control below base speed and the square wave control above base speed can be realized. Simulation and experimental results demonstrate the correctness and effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Abstract In this study, a compound control strategy for motor side and quasi‐Z source side is proposed to improve the robustness of the quasi‐Z source permanent magnet synchronous motor drive system subjected to external disturbance. In this method, the complementary sliding mode control and sliding mode control as feedback controllers are combined with the disturbance observer technology as a feed‐forward compensator to achieve fast tracking and disturbance suppression for the PMSM drive system. Firstly, the signal models of quasi‐Z source inverters and motors are established. Secondly, by introducing state variables, the composite sliding mode controller is designed with strong robustness based on matched disturbances. Then, in order to further improve the disturbance suppression performance, a disturbance observer based on a feed‐forward compensator is designed to estimate the mismatched external disturbances in the motor drive system. Finally, the global asymptotic stability based on Lyapunov criterion is proved. The simulation and experimental results show that the proposed compound control strategy has the advantages of fast convergence, small motor speed pulsation and strong robustness to external disturbances.

The authors show a PM motor drive with the maximum speed of 170,000 r/min for a super‐high‐speed centrifugal air compressor, which is used in high‐altitude unmanned aerial vehicle (UAV). Conventional turbochargers used in high‐altitude UAV are usually driven by the exhaust of the engine in the fuel cell system; however, the exhaust is composed of vapour and water drop, which can't drive a mechanical turbocharger effectively. In this circumstance, a super‐high‐speed electric centrifugal compressor becomes attractive to boost the air pressure and improve overall efficiency. A wide‐speed‐adaptive sliding mode observer (WSA‐SMO) is adopted to realise the super‐high‐speed sensorless control. A super‐high‐speed motor drive system is developed based on the WSA‐SMO. The current waveform at 170,000 r/min is shown to prove the steady state performance. The acceleration curves and start/stop curves are shown to demonstrate the excellent dynamic performances. [ABSTRACT FROM AUTHOR]

In this study, a compound control strategy for motor side and quasi‐Z source side is proposed to improve the robustness of the quasi‐Z source permanent magnet synchronous motor drive system subjected to external disturbance. In this method, the complementary sliding mode control and sliding mode control as feedback controllers are combined with the disturbance observer technology as a feed‐forward compensator to achieve fast tracking and disturbance suppression for the PMSM drive system. Firstly, the signal models of quasi‐Z source inverters and motors are established. Secondly, by introducing state variables, the composite sliding mode controller is designed with strong robustness based on matched disturbances. Then, in order to further improve the disturbance suppression performance, a disturbance observer based on a feed‐forward compensator is designed to estimate the mismatched external disturbances in the motor drive system. Finally, the global asymptotic stability based on Lyapunov criterion is proved. The simulation and experimental results show that the proposed compound control strategy has the advantages of fast convergence, small motor speed pulsation and strong robustness to external disturbances. [ABSTRACT FROM AUTHOR]

This paper presents a diagnostic method of inverter open‐switch and open‐phase faults in multiphase permanent magnet synchronous motor (PMSM) drives. First defined are adequate variables called virtual current vectors. The projection of the zero‐sequence current component on these variables was used to define two simple fault indices. High sensitivity to fault is thus induced but with a good robustness to transient states and variation of machine parameters. The mathematical development of the proposed method is provided and supported by experimental tests conducted on two prototypes of multiphase machines in the laboratory: sinusoidal and bi‐harmonic PMSMs. The experimental results confirm the effectiveness and the robustness of the proposed method and its capability to detect the single and multiple open‐switches and open‐phase faults in the electric drive. [ABSTRACT FROM AUTHOR]

Abstract In the traditional finite control‐set model predictive direct speed control (FCS‐MPDSC), the coupling items in the current equation have been ignored because of predictive complexity, leading to imperfect prediction accuracy and control performance. Meanwhile, the current error and speed error are both included in the weighted sum cost function. The two types of errors lead to the difficulty of weight coefficients' distribution, which can only rely on subjective experiences. Thus, an FCS‐MPDSC strategy based on the 2nd‐Taylor‐series model with quadratic cost function is proposed. The dynamic performance has been greatly improved because the input variables of the Taylor series model are unified as the basic voltage vector with the same control period. And the static error is also reduced as the weight coefficient matrix of the quadratic cost function is solved offline. On this basis, the verification experiments are carried out. The results show that a better dynamic and static performance is achieved at the same time by the proposed strategy.

Abstract The two‐voltage‐vector (2VV) model predictive torque control (MPTC) has been widely discussed and compared to the conventional single‐voltage‐vector (1VV) MPTC in permanent magnet synchronous motor drive applications, where it was shown to have quick response and low torque ripple. An improved 2VV‐MPTC is set forth based on extended control set. In the proposed approach, the reference voltage vector is calculated using the established torque and flux deadbeat control and optimal calculation of the duty cycles. Moreover, to further improve the torque performance, the proposed algorithm is extended to three‐voltage vector (3VV), which is shown to achieve even better performance. Experimental results demonstrate that the proposed 2VV and 3VV‐MPTC algorithms have better computation efficiency and can significantly reduce torque ripple compared to the previous methods.

Adjustable-speed drives with single-phase input require a power factor correction front-end, usually implemented by a boost converter, to reduce the current distortion from the uncontrolled rectifier; this stage is then followed by a three-phase inverter. Bulky electrolytic capacitors are used to limit the direct current voltage ripple resulting from the rectification of the single-phase input. This leads to increased system size and shorter lifetime. In this work, the usual boost front-end is exploited to actively control the DC link voltage ripple while limiting the input current distortion and, hence, the power factor, even if not reaching unity. However, Power Factor is greatly improved with respect to the uncontrolled rectifier alone. This approach permits one to reduce the required capacitance, allowing the substitution of the electrolytic capacitor with a long-life low-equivalent-series-resistance film one. A control targeting capacitor voltage level, ripple, and boost inductor peak current is presented, together with practical design models. The synergic control of the boost front-end and of the machine drive is presented as well. The resulting converter is tested with resistive load and permanent-magnet synchronous machine drive, highlighting the advantages and limits of the proposed solution. [ABSTRACT FROM AUTHOR]

Abstract Predictive current control (PCC) is a promising technique for adjustable speed drives due to its intuitive features such as quick response, easy inclusion of non‐linearities and constraints as well as multi‐variable operation. The conventional predictive current control (C‐PCC) employs a cost function to choose the optimum vector, which reduces the error between the reference and the predicted current. Even though the C‐PCC can achieve excellent dynamic performance with a single active voltage, the steady‐state performance is affected with larger torque and flux ripples. When two voltage vectors are applied in a control interval, the steady‐state performance is improved. This paper proposes a modified duty‐based PCC for permanent magnet synchronous motor (PMSM) drives, employing an active and null vector in control interval, where the duration for which the optimal active vector is applied is based upon a simple error based calculation. The proposed duty calculation requires a simple constant and eliminates the need for current slope calculation, which results in parameter insensitive operation. The proposed method is compared with C‐PCC and recently published works based on duty calculation. The simulation and hardware experiments conducted on a PMSM drive confirm the effectiveness of the proposed method with reduced torque and flux ripples.

This study investigates a small film DC-link capacitor inverter for a permanent magnet synchronous motor drive system. Two control methods, including a d–q-axis current control and a positive torque region current control, are originally proposed to improve the torque dynamics of the drive system. In addition, a damping compensation method is used to improve the input power factor and reduce the input current harmonics. A current-loop predictive controller and a speed-loop predictive controller are first proposed to improve the dynamic responses of the interior permanent magnet synchronous motor drive system. To implement the drive system, a digital signal processor, TMS 320LF2808, is used as a control centre to execute the control algorithms. Experimental results can validate the correctness and feasibility of the proposed methods.

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM) drives is a noticeable practice in industrial applications due to its quick dynamic performance. However, due to the presence of hysteresis controllers and inaccurate switching tables especially for the multilevel fed DTC drives are facing higher ripples in torque and flux response. An improved DTC for three‐level open‐end winding PMSM drive is proposed in this article and features reduction of flux and torque ripples. The torque and flux performances of the PMSM are directly controlled by the calculated reference voltage vector in the stationary reference frame. The voltage vector tables are proposed based on the length of the voltage space vectors and the actual voltage vector nearer to the calculated reference voltage vector is selected so that the minimum ripples exist in flux and torque responses. The steady‐state and dynamic conditions of the proposed DTC method are verified in the real‐time experiment and also compared with the conventional DTC as well as the recently developed control methods. [ABSTRACT FROM AUTHOR]

This study proposes a model predictive control (MPC) method with a fixed weighting factor for three‐phase four‐switch inverter‐fed permanent magnet synchronous motor drives to suppress the capacitor voltage offset. The prediction model of the capacitor voltage difference is obtained based on the relationship between capacitor voltage and phase current. Then by analysing the relationship between basic voltage vector, electromagnetic torque and flux amplitude, the control of electromagnetic torque and flux in the model predictive torque control is transformed into the control of the voltage vector. The dimension of the capacitor voltage difference is the same as that of the voltage vector, hence the cost function with the fixed weighting factor is defined with the consideration of the capacitor voltage offset suppression. The effectiveness of the proposed MPC method is validated by the simulation and experiment. [ABSTRACT FROM AUTHOR]

Due to the voltage limitation of the inverter DC‐link of railway traction systems, six‐step operations are widely used in the high‐speed region to improve the voltage utilization and increase the maximum fundamental frequency. The magnitude of the output voltage fundamental harmonic reaches the maximum for six‐step operations, while only the phase angle can be adjusted. This limitation makes it challenging to control the instantaneous current of permanent magnet synchronous motors (PMSM). This paper proposes a single d‐axis current regulator flux‐weakening control scheme to improve the current control over six‐step operations of PMSM without changing the inverter output voltage modulation ratio by controlling only one degree of freedom. The voltage in six‐step operations is generated by synchronous space vector pulse width modulation based on basic bus clamping strategy with an effective limitation of the switching frequency in the full‐speed region. A simplified model of the current regulator is developed for the analysis and design of the controller parameters. This paper presents clear rules for entering and quitting six‐step operations effectively to achieve a smooth transition between double current regulators and the single current regulator control. The numerical results are verified by experimental measurements on a 7.5 kW PMSM drive. [ABSTRACT FROM AUTHOR]

The six‐phase direct‐drive permanent magnet synchronous motor (DDPMSM) has a good prospect in electric vehicles, ship propulsion, aerospace and other fields due to the advantages of low voltage, high power, low speed and high torque. In this study, a six‐phase DDPMSM is proposed with 60° phase‐belt toroidal winding configuration (60°‐TW). Different from traditional overlapping windings, each coil of 60°‐TW is wound onto the stator yoke in the same direction. The topology of the proposed motor is introduced, and its operation principle is analysed by describing the variation of the magnetic field produced by the six‐phase 60°‐TW versus time. Meanwhile, based on the same power grade and effective volume, the six‐phase PMSM and dual‐three phase PMSM with different winding arrangements are designed. The magnetic field distribution, back‐EMF, cogging torque, torque and loss characteristics are explored in detail. The results show that the proposed six‐phase DDPMSM with 60°‐TW has the characteristics of low speed and high torque in comparison to the traditional six‐phase PMSM and dual‐three phase PMSM, which is expected for direct‐drive systems. [ABSTRACT FROM AUTHOR]

In this article, an electrical braking torque limit trajectory is designed to improve the regenerative braking of electric vehicles based on a regenerative power analysis. Even though electric motors generally regenerate electric energy from kinetic energy, the drive system dissipates electric energy under certain low-speed operation conditions. This phenomenon has been addressed in many previous works and most of them compensate for this power dissipation region by modifying the electrical braking torque limit trajectory of the motor. However, the torque limit trajectory has never been considered based on a regenerative power analysis even though an inaccurate torque limit trajectory causes energy loss to the drive system. In this article, the regenerative power analysis for two major kinds of permanent magnet synchronous motor is performed. Afterward, torque limit trajectories are set based on this analysis so that batteries in electric vehicles can harvest the maximum regenerative energy in any circumstance. To verify the analysis and proposed torque limit trajectories, simulations and experiments are performed. [ABSTRACT FROM AUTHOR]

The zero‐voltage vector (ZVV) method is widely employed to restart a free‐running permanent magnet synchronous machine (PMSM) stably in a sensorless drive system due to its simple implementation. However, in the conventional method, it is hard to determine the action time and interval time of ZVV pulses, which may result in overcurrent. Moreover, the estimation accuracy is susceptible to current measurement noise. To cope with these problems, an enhanced ZVV method based on two feedback loops is proposed. With the proposed strategy, an inner closed loop is constructed to regulate the action time of the ZVV pulse by keeping the current amplitude at the reference value, which prevents the overcurrent. Meanwhile, the reference value of the current amplitude is adjusted automatically based on the outer loop to determine a suitable interval time of the ZVV pulse. Furthermore, the phase‐locked loop technique is exploited to extract rotor speed and position. The feasibility of the proposed method is verified under simulation and experimental results with a 5.5 kW sensorless PMSM drive system. [ABSTRACT FROM AUTHOR]

This study confers a novel approach towards fuzzy‐PI (proportional–integral) controlled pulse width modulation (PWM) controlled permanent magnet synchronous motor (PMSM) drive operated through a conventional voltage source inverter (VSI) supplemented with buck‐converter fed current source inverter (CSI). It is observed that in a PWM controlled VSI, output voltage and current obtained contains certain harmonic distortion. A buck‐converter fed CSI is capable of minimising the voltage and current ripples prominently even with the application of PWM. Thereby, in this study, an economic, as well as robust design procedure for the buck converter, fed CSI is proposed. Moreover, a particle swarm optimisation (PSO) mechanism is introduced to optimise the performance of the proposed fuzzy logic controller. Additionally, an over‐current protection scheme of the PMSM motor is proposed. The performance of a PMSM drive is analysed in MATLAB/SIMULINK platform. Furthermore, the proposed concept is tested and verified in a real‐time test‐bench developed in the laboratory. Finally, from the performed test conditions, it can be confirmed that the proposed current control strategy of the drive system shows excellent performance in various operating conditions and can be employed in light‐weight electric vehicles. [ABSTRACT FROM AUTHOR]

This study presents a combined vector and direct torque control (CVDTC) for surface‐mounted permanent magnet synchronous motor (SM‐PMSM). The CVDTC method has a fast dynamic torque response without requiring any conventional PWM signal‐generators. Besides, it provides low‐speed control and standstill operation, torque and flux ripple reduction, minor switching frequency variations, and low computational burden. In this study, CVDTC is mathematically analysed in the stator flux reference frame and then both DTC and CVDTC are simulated and compared for SM‐PMSMs. To further reduce torque and flux ripple, model predictive combined vector and direct torque control (MPCVDTC) with the finite control set is analysed and proposed in the stator flux reference frame. Moreover, maximum torque per ampere (MTPA) and constant stator flux magnitude analysis for SM‐PMSM are explored in the stator flux reference frame. Simulation and experimental results substantiate the effectiveness and performance of the CVDTC and MPCVDTC methods over a vast speed range. [ABSTRACT FROM AUTHOR]

In this study, an advanced predictive control system is proposed which consists of two cascade predictive controllers; the first one minimises the power losses while the second one minimises the torque ripple. In the first controller, motor losses are formulated as a function of stator‐flux linkage components. Then, the optimal stator‐flux linkage vector which causes the minimum losses is found by adopting fast‐iterative shrinkage thresholding algorithm (FISTA). The second controller is a predictive direct torque controller adopted to control the stator‐flux linkage and torque directly. In this controller, torque ripple is formulated as a function of the stator‐voltage vector. Then, the optimal voltage vector which causes the minimum torque ripple is found by adopting FISTA. In the second controller, deadbeat control of the stator‐flux linkage is considered as a constraint in minimisation of torque ripple. To assess the effectiveness of the proposed control system, performance of the motor is assessed through various experimental tests, where the results confirm that the proposed control system minimises the power losses and torque ripple, simultaneously. The comparative assessment with the recent predictive controllers indicates that the proposed control system has higher efficiency as well as lower torque ripples in all operating points. [ABSTRACT FROM AUTHOR]

This study proposes a diagnosis method for open-circuit faults of six-phase permanent magnet synchronous motor. When the open-circuit fault occurs in the single-bridge arm or the double-bridge arm, wavelet transform extracts the trigger signal of fault, and the z1–z2 plane current component is analysed. Seven kinds of fault modes are defined by analysing the characteristics of the scatter plot of the z1–z2 plane current component. The fractal dimension of the z1–z2 plane current component scatter plot is calculated to accurately quantify the fault modes. Moreover, 13 fault areas are defined by analysing the current centroid position of the z1–z2 plane current component. First, the diagnosis of two particular kinds of fault modes is completed by selecting the fault area. Besides, the diagnosis of the remaining five kinds of fault modes is completed by combining the fault area and the fault mode. The conditions for judging all open-circuit faults are summarised to establish a fault database. All the open faults can be diagnosed by searching the fault database by the proposed method. Finally, the effectiveness of the method is verified by experiments. [ABSTRACT FROM AUTHOR]

A smooth changeover from the I‐f method to closed‐loop sensorless vector control is a critical requirement for permanent magnet synchronous motor (PMSM) drives using a back‐emf based sensorless algorithm for medium‐ to high‐speed range control. The existing methods provide a smooth transition by aligning the angle generated by I‐f control to the sensorless estimated angle. However, the overall start‐up time increases due to the additional transition interval, which limits the usability of these methods for applications requiring a quick start‐up. Furthermore, the use of a direct transition method to reduce the changeover time results in speed and current oscillation if the estimated position using sensorless algorithm is having an error. In the proposed method, the inverter pulses are disabled for a short duration and the machine back‐emf is measured after the stator current falls to zero. Therefore, a quick and seamless transition is achieved in the proposed method by accurately estimating the rotor position from the sensed back‐emf. The proposed method is also extended to perform on‐the‐fly start for power failure ride through during short time power supply interruption. The performance of the proposed method is verified using simulation and experiment on a 25 kW PMSM drive. [ABSTRACT FROM AUTHOR]

A general analytical model, which is applied to pre‐estimate the air‐gap magnetic field of interior permanent magnet synchronous motors (IPMSM) under the no‐load and load conditions, is proposed in this study. First, the analytical formulas of both the slotless permanent magnetic field and the armature reaction magnetic field are derived, respectively, by virtue of solving the Laplace field equation in polar coordinates. Then, the complex relative permeance is employed to account for the slotting effect. Subsequently, the proposed analytical model, which can reflect the spatial and temporal distribution characteristics of the air‐gap magnetic field, has been applied in a 4‐pole‐24‐slot IPMSM as an example. Finally, the analytical air‐gap magnetic field with the spatial order and frequency characteristics is validated by the finite‐element result. Additionally, the consistency between the analytical and finite‐element results further indicates that the proposed analytical model is effective. [ABSTRACT FROM AUTHOR]

Saturation and cross‐coupling effects have a significant impact on the magnetic behaviour of a permanent magnet synchronous motor (PMSM), which cannot be analysed by the conventional linear model in the direct and the quadrature axis. This study introduces a precise two‐axis flux linkage model for PMSMs to offer a better depiction of the relationship between the flux linkages and corresponding currents. A parameter determination methodology is developed to identify the model parameters for a PMSM, and based on these works; the condition of a PMSM can be estimated. The process requires no geometrical parameter of the machine and little computational effort. Once the model parameters are determined, the torque estimation of a PMSM is simple enough to be made in real‐time in a motor drive controller. Finite‐element analysis and experimental results demonstrate the feasibility and accuracy of the improved model. It follows that the proposed non‐linear PMSM model based on current injection and bivariate function approximation can significantly enhance modelling precision of flux linkage and inductance over the entire range of current excitation in the application of PMSM drive. [ABSTRACT FROM AUTHOR]

In this paper, an improved modulated model‐predictive control (MMPC) scheme is proposed for the current control of permanent magnet synchronous motors (PMSMs). Different from the existing MMPC based motor current control schemes which simply feed the resultant voltage vectors calculated by the finite‐control‐set model predictive control (FCS‐MPC) to the SVPWM module and could not adjust the current control bandwidth, the principle of the proposed MMPC current control scheme is to control the current vector along a predefined trajectory and the resultant current vector is expected to equal the reference current vector at the end of the predictive horizon. Therefore, the control bandwidth of the proposed MMPC can be easily adjusted via the predictive horizon, and the transient performance of the current control can be improved without current overshoot. Moreover, different from existing MMPCs, the proposed control scheme does not need to predict all the resultant currents generated by the basic voltage vector combinations of the six voltage sectors, but only needs to predict the resultant currents generated by the basic voltage vector combinations of three voltage sectors. Therefore, the computational burned is significantly reduced. [ABSTRACT FROM AUTHOR]

The performance of the conventional model predictive current control (MPCC) method is not without steady‐state ripples in electrical drives. Although some recently proposed MPCC methods have succeeded to mitigate this drawback, they have led to reductions in the dynamic speed response inherent to the conventional MPCC method. An improved MPCC is proposed here which would enhance the conventional MPCC method without any side effect on its merits. In this proposed method, three control strategies are presented for transient‐ and steady‐state operations. The first two strategies are applied to improve motor performance in the steady state, through calculating the voltage vector (VV) and its optimal duration to minimise ripples in both d–q ‐axis currents. The third strategy is applied in the transient‐state operation, where, instead of two VVs, an allowable non‐zero VV is applied throughout the control cycle to prevent dynamic response reduction caused by zero VV. The experimental results confirm the effectiveness of this proposed method in reducing torque ripples, flux ripples, and the stator current total harmonic distortion in relation to those obtained by the previous MPCC methods. [ABSTRACT FROM AUTHOR]

This Letter proposes a novel technique for automatic position offset calibration for permanent‐magnet synchronous machine (PMSM) drives. Contrary to existing methods, the proposed technique estimates and compensates for the position offset without using machine true parameters or signal injection, which is possible under the condition of zero‐current control at high enough speed where parameter‐dependent terms are eliminated. To achieve this condition using uncertain parameters, speed control with absolute value feedback and model‐free current control are devised. Additionally, under this condition, not only the misalignment of the position sensor but also the sensor delay can be considered as the position offset, which improves the accuracy of the calibration. The proposed approach will be verified by experimental results. [ABSTRACT FROM AUTHOR]

The torque enhancement of the dual three‐phase permanent magnet synchronous machine (DT‐PMSM) drive system by full exploitation of flux‐linkage and current harmonics is comparatively studied in this study. The torque capability of DT‐PMSM is previously evaluated with strategies of harmonics utilisation, i.e. strategy 1 of third harmonic utilisation and strategy 2 of fifth and seventh harmonic utilisation, which can extend the torque capability by 18.2 and 9.0%, respectively. However, the full exploitation of harmonics including third, fifth, and seventh harmonics in the dual three‐phase system is not addressed. In this study, the strategy 3 of third, fifth, and seventh harmonic utilisation is also included. Its corresponding harmonic current control is proposed and the average torque and harmonic torque are analysed in detail. Based on a test rig with existing prototype DT‐PMSM, the torque with strategy 3 is increased up to 26.5%, which is superior to the previous strategies. [ABSTRACT FROM AUTHOR]

The rare earth permanent magnet (PM) is widely used for traction motors of hybrid and electric vehicles. These motors have more torque density compared to any other type of motors. However, these PMs have the problems of limited reserves, unstable supply, and high cost. For solving these problems, concentrated flux synchronous motor (CFSM) and multi‐layer interior permanent magnet synchronous motor (IPMSM), using ferrite PMs, are compared in this study. The CFSM and multi‐layer IPMSM are introduced and compared with regard to shape, size, electric parameter, and motor characteristics. In addition, two types of motors are fabricated and tested in order to verify their performance and feasibility. Finally, comparing the merits and demerits, the comparative motor types are estimated in this study. [ABSTRACT FROM AUTHOR]

Generalised predictive control (GPC) is known for its good dynamic performance and long prediction horizon, but the performance can be severely deteriorated when measurement noises exist due to the wide control bandwidth of GPC. Meanwhile, the unmodelled periodic disturbances can cause ripples to the output variables. In this study, a practical permanent magnet synchronous motor (PMSM) drive system with speed measurement noise and periodic disturbances is considered, for which a novel multivariable GPC method is proposed to achieve both good dynamic performance and speed ripple mitigation. The proposed method has a simple structure, since the traditional cascaded speed and current control loops are replaced by a non‐cascaded one. To reject the measurement noise without jeopardising the system stability, an internal low‐pass filter is embedded in the GPC. Meanwhile, external resonant loops are added to the GPC to mitigate the low‐order speed ripples caused by the periodic disturbances. Furthermore, a deadbeat‐based current constraint method is proposed to avoid overcurrent during transient processes. Theoretical stability analysis of the proposed method is presented. Experimental results show that the proposed method has good steady‐state and dynamic performances, including measurement noise rejection and speed ripple mitigation. [ABSTRACT FROM AUTHOR]

A novel direct torque control (DTC) using rotating sector switching table is proposed for a matrix converter (MC) fed permanent magnet synchronous motor (PMSM) system in order to minimise common‐mode voltage of the system, exploiting MC rotating vector's advantage of generating zero common‐mode voltage. To overcome the difficulty that the angle between adjacent rotating vectors varies according to the phase of input voltage, the rotating vectors are classified into two groups, and each group of vectors have identical rotating direction and fixed angle between adjacent vectors. Rotating sectors of the vector plane are then established, and concise switching table is put forward for the MC‐DTC. Experiments are carried out on a 1.6 kW prototype. The results demonstrate considerable common‐mode voltage reduction and adequate dynamic performance of the proposed MC‐DTC. [ABSTRACT FROM AUTHOR]

A hybrid direct torque control (DTC) method is proposed in this study for a permanent magnet synchronous motor (PMSM) drive based on the finite‐set control (FSC). After selecting the optimal voltage vectors, the steady‐state torque and flux ripple is minimised using the conventional DTC and the most efficient and dynamically‐fast mode of the control algorithm. The philosophy of the control approach proposed is based on the FSC and DTC. In other words, the process of optimisation relies on a combination of FSC DTC. Compared to conventional PMSM drive control, the proposed technique optimises the switching state of the inverter and minimises the cost function by adopting measures resembling DTC. In addition, the sensitivity of this method to motor parameters is very low, and it is computationally simple. The results obtained from the experiments and simulations validated the applicability of this method to PMSM drives by suggesting that the proposed model provides dynamically‐fast responses to low torque and flux ripples using a simple‐to‐implement hybrid structure. [ABSTRACT FROM AUTHOR]

This study proposes an effective diagnosis method for single and multiple open‐switch faults (OSFs) in three‐phase permanent magnet synchronous motor (PMSM) drives. The proposed method is based on the real‐time estimation of the three‐phase motor currents using three Kalman filters (KFs). Three residual signals are defined as the differences between the three‐phase measured and estimated stator currents. The averaged normalised residual signals are used as diagnostic criteria for the detection of OSFs. The proposed method accurately detects the OSFs, localises the faulty switches and effectively discriminates between the OSFs and current sensor faults. The main superiorities of the proposed KF‐based method are its fast detection time and high robustness to measurement noises/errors and load variations. Moreover, the proposed method is useful for both closed‐loop and open‐loop PMSM drives. The proposed method can be embedded as a subroutine in the drive control unit without any hardware extension. The effectiveness of the proposed method is confirmed through extensive simulations and several hardware‐in‐the‐loop experiments on a testbed with a 1.5 kW PMSM and dSPACE1104 control board. In addition, the real‐time feasibility of the proposed method using low‐cost microprocessor technology is guaranteed by testing it on TMS320F28335 from Texas Instruments©. [ABSTRACT FROM AUTHOR]

In this study, a new approach based on adaptive dynamic programming (ADP) is proposed to control permanent magnet synchronous motors (PMSMs). The objective of this study is to control the torque and consequently the speed of a PMSM when an unknown load torque is applied to it. The proposed controller achieves a fast transient response, low ripples and small steady‐state error. The control algorithm uses two neural networks, called critic and actor. The former is utilised to evaluate the cost and the latter is used to generate control signals. The training is done once offline and the calculated optimal weights of actor network are used in online control to achieve fast and accurate torque control of PMSMs. This algorithm is compared with field oriented control (FOC) and direct torque control based on space vector modulation. Simulations and experimental results show that the proposed algorithm provides desirable results under both accurate and uncertain modelled dynamics. Although the performance of FOC method is comparable with ADP under nominal conditions, the torque and speed response of ADP is better than FOC under realistic scenarios, that is, when parameter uncertainties exist. [ABSTRACT FROM AUTHOR]

In some cases, LC filters are installed between the inverters and motors to suppress the adverse effects of pulse width modulation. However, some techniques should be modified, because the mathematical model of the drive system is changed by the LC filter and the sensors on the inverter output cannot measure some necessary variables. In this study, a multi-purpose proportional-integral (PI) observer is proposed at first. The type of observer depends on whether the position sensor is equipped. A sliding mode controller for the LC filter based on the observer is presented, therefore improving the dynamic performance. Furthermore, if the position sensor of the rotor is equipped, an open-switch fault diagnostic method is realised by means of the PI observer; if the position sensor is not equipped, the sensorless estimation is realized. The proposed strategies were realised without any additional current/voltage sensors. Experimental results verified the effectiveness of the proposed strategies. [ABSTRACT FROM AUTHOR]

In this study, a non‐ideal single‐phase 50 Ω, 50/250 μH + 5 Ω V‐network line impedance stabiliser network (LISN) is modelled, to show how the impedance characteristic of the LISN affects the common‐mode (CM) and differential‐mode (DM) conducted electromagnetic interference (EMI) modelling and measurements. The equivalent CM and DM single‐phase models of a permanent magnet synchronous motor (PMSM) variable speed drive (VSD) system are developed based on CM and DM impedance characteristics of different parts of the system. Using the proposed single‐phase CM and DM circuits, the authors introduce the LISN correction factor, which shows the relation between the EMI measured in different frequency ranges and the LISN impedance characteristic. The LISN correction factor is calculated for three different cases. It is shown how the EMI measurement can be modified by the LISN correction factor to have more accurate results. MATLAB Simulink is used for the time‐domain analysis of the system. However, the proposed method can be used in both frequency‐domain and time‐domain analyses. Results given by the proposed method is verified with experimental EMI measurements. The outcome of this study can be used for a more accurate conducted EMI prediction, measurement, and a better EMI filter design. [ABSTRACT FROM AUTHOR]

This study investigates a small film DC-link capacitor inverter for a permanent magnet synchronous motor drive system. Two control methods, including a d–q-axis current control and a positive torque region current control, are originally proposed to improve the torque dynamics of the drive system. In addition, a damping compensation method is used to improve the input power factor and reduce the input current harmonics. A current-loop predictive controller and a speed-loop predictive controller are first proposed to improve the dynamic responses of the interior permanent magnet synchronous motor drive system. To implement the drive system, a digital signal processor, TMS 320LF2808, is used as a control centre to execute the control algorithms. Experimental results can validate the correctness and feasibility of the proposed methods. [ABSTRACT FROM AUTHOR]

The model predictive current control (MPCC) is popular and widely used method for permanent‐magnet synchronous motor (PMSM) and the tuning of weighting factor in classical cost function (CF) of MPCC of PMSM is not required. A three‐level inversion‐fed open‐end winding PMSM (OEW‐PMSM) would produce lesser torque and stator flux ripples; however, computation time required for the prediction of control variables is large. This study proposes a control method to three‐level inversion‐fed OEW‐PMSM for reduction of computational time without affecting the performance when compared with conventional MPCC. The proposed method uses a maximum four voltage vectors (VVs) instead of 19 VVs in three‐level conventional MPCC. The reduced VVs decrease the number of predictions and computational time for predictions. CF in terms of voltage is used, thereby eliminating the need to predict the currents and faster execution of algorithm is achieved. A higher sampling rate is possible to achieve using the proposed method; thereby, reducing the steady‐state ripples in developed torque and stator flux, and improving the percentage total harmonic distortion of stator current. The effectiveness of the presented control method is practically verified after comparing its computational time, steady‐state response and dynamic response with that of three‐level conventional MPCC. [ABSTRACT FROM AUTHOR]

This study proposes a sensorless flux adaption direct torque and flux control (DTFC) for an interior permanent magnet synchronous motor (IPMSM), in which an maximum torque per ampere (MTPA) based on active flux and an adaptive second-order sliding mode observer (SOSMO) are adopted. Flux adaption DTFC is proposed based on the existing active flux concept. Thus, the stator current amplitude can be minimised in both steady state and transient state. Furthermore, to realise the sensorless control of the IPMSM, an adaptive SOSMO is proposed. Compared with constant gains SOSMO, the gains of the adaptive SOSMO can be adjusted adaptively with the motor speed changing. Then, the precision of position estimation is enhanced effectively in a wide speed range. Numerical simulations and experiments with a 60 kW IPMSM are implemented. In addition, the results validate the capability of the proposed sensorless flux adaption DTFC scheme. [ABSTRACT FROM AUTHOR]

Deadbeat control calculates excitation by a differential equation model that takes measurements of state variables as initial values and instructions as terminal values. Ideally, this excitation can force state variables to track instructions in the succeeding control interval. However, in a practical system, noises in measured signals can mislead the control system and degrade its performance with increased ripples and harmonics. Therefore, some filters are often used in measurements, but their inherent delay can lead to inaccurate initial values and cause severe overshoots in dynamic cases. In this study, a new type filtering algorithm called predictive deviation filter is proposed for deadbeat control, which filters only the predicted deviation obtained by removing the expected values from measured ones, and then the real values of state variables are recovered. With this method, the influence of the filter delay can be limited only on the deviation which is a small part of the signal, significantly improving the accuracy of the initial values. Furthermore, a comprehensive frequency‐domain analysis of the predictive deviation filter is provided. Finally, the new filtering algorithm is applied to drive control of permanent magnet synchronous motor. The simulation and experimental results verify the effectiveness and performance of this approach. [ABSTRACT FROM AUTHOR]

The multiphase motor drives have attracted more and more attention during the last decade since they offer advantages of high‐power rating, lower voltage and current stresses in semiconductor switches, and high‐fault‐tolerant ability, compared to the conventional three‐phase drives. This study presents a novel two‐step model predictive control (MPC) method for currents in two‐level voltage‐source inverters fed dual three‐phase permanent magnet synchronous motor drives, aiming at reducing the switching frequency and computation burden of the system. In the first step, the proposed method searches the phase having the maximum phase current error among six phases, and then changes the switching signal of that phase depending on the requirement of current change. Thus, overlarge error in the hysteresis‐based predictive control is avoided. In the second step, switching signals are changed in two phases at most and only six voltage vector candidates are evaluated with MPC within one sampling period. So, the switching frequency is reduced and the computation burden is released compared to the conventional finite‐control‐set ‐MPC method. Finally, the experimental results are given to verify the validation of the proposed scheme and compare the performance to the other classical MPC methods. [ABSTRACT FROM AUTHOR]