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A novel position estimation strategy based on lag compensation-assisted adaptive quasi-fading Kalman filter (LC-AQFKF) is proposed for synchronous reluctance motor (SynRM) sensorless drive in this article. In LC-QFKF, the quasi-fading factor is derived to avoid the harsh assumptions of conventional adaptive fading Kalman filter, and accessibility of the method is improved while ensuring the estimation accuracy. The computational efficiency of LC-AQFKF is promoted by introducing the quasi-fading factor into the prediction error covariance matrix. Moreover, the frequency characteristic of AQFKF-based active back electromotive force observer is analyzed, and the phase lag problem in high-speed situations caused by the low-pass filtering property of AQFKF is overcome. In this way, the estimation accuracy of the rotor position is significantly enhanced. Besides, the double dynamic position compensation method is put forward to strengthen the position estimation performance of sensorless SynRM drive under dynamic conditions. The effectiveness of the proposed scheme is validated at a 1.5 kW SynRM drive. [ABSTRACT FROM AUTHOR]

To optimize the current-control performance of the linear permanent magnet synchronous motor (LPMSM) drive system, a robust continuous time model-based predictive control for the LPMSM drive systems is proposed in this article. Since the current regulation technology is fundamental for obtaining the precise thrust of the LPMSM, a continuous time model-based predictive control is utilized in the current loop to achieve a fast dynamic response and accurate tracking accuracy. However, the predictive control is a model-based scheme, thus, the model uncertainties and parameter variations will influence the accuracy of stator current. To solve this problem, an augmented internal model disturbance observer is proposed to estimate the lumped disturbances and then compensate to the forward channel. First, the internal model equation of the current loop is constructed by the internal model control principle. Then, a new augmented matrix is constructed by introducing the error variables of the actual current and the internal model current. The observer control law is designed by the state feedback theory, and the observer parameters are optimized by pole assignment method. Finally, the experimental results demonstrate the correctness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

To improve the stability and accuracy of the estimated position using the conventional sliding mode observer (CSMO) under low frequency ratio (LFR), this article proposes a novel discrete-time synchronous-frequency adaptive observer (SFAO) for surface-mounted permanent magnet synchronous motor (SPMSM) sensorless drives. The proposed SFAO has merits of high amplitude and zero-phase lag of resonant controller at synchronous frequency. The sign function and the low-pass filter (LPF) of CSMO in the proposed observer can be removed and conducive to dispel the inherent chattering of the CSMO as well as phase shift produced by the LPF. Then, taking into account the digital control delay and discretization truncation error, an exact complex-vector discrete-time model in the stationary coordinate is developed. Based on that, the direct discrete-time domain design approach is utilized in the proposed observer, which can be devised by pole placement directly on complex z-domain to assure the stability and position estimation accuracy under LFR. Finally, the availability of the proposed discrete-time SFAO scheme is verified via experiments on a 2.1-kW SPMSM drive. [ABSTRACT FROM AUTHOR]

To achieve high-performance control of the precise linear permanent-magnet synchronous motor (LPMSM) control system, a composite robust current regulation method with good dynamic response and disturbance rejection performance is proposed. First, a continuous time model predictive current control is utilized to obtain superior current response. Since the predictive current control has a strong dependence on the precise mathematical model of the controlled plant, there will be static current error and even system instability when model mismatch and parameter variation. Then, aiming at this problem, the adaptive disturbance observer is applied to compensate the lumped disturbance. However, the adaptive disturbance observer designed based on the single model adaptive law has some disadvantages, such as low precision, long regulation time, poor transient response, and so on. Consequently, a multiple-models adaptive disturbance observer is proposed, which improves the convergence speed of disturbance estimation and system's robustness against parameter perturbation and model mismatch. Finally, a 0.9-kW LPMSM is used as a case study, and the experimental results show the effectiveness of the proposed solution, both during the transient and steady-state operating conditions. [ABSTRACT FROM AUTHOR]

Due to various nonideal factors, including the motor parameter mismatches, detection errors, converter nonlinearities, noise, etc., dc bias and high-order harmonics exist in the flux model, which make the traditional flux observer estimation inaccurate. In order to suppress dc bias and high-order harmonics, an interior permanent magnet synchronous motors (IPMSM) sensorless drive method based on a fifth-order flux observer (FOFO) is proposed in this article. The proposed FOFO can completely remove dc bias and has a strong filtering ability for high-order harmonics. Additionally, the parameters of the FOFO are set through the s-domain analysis. Then, the discrete FOFO is obtained for better implementation in digital systems. The proposed FOFO is verified by experiments on a 2.0-kW IPMSM drive platform. [ABSTRACT FROM AUTHOR]

A traditional linear extended state observer (LESO) does not have enough capacity to handle the rapidly-varying back electromotive force (EMF). This key weakness limits the application of LESO in the internal permanent magnet synchronous motor (IPMSM) sensorless control system. In this article, an IPMSM sensorless drive method using an improved LESO (ILESO) is proposed. The ILESO consists of a pure integral and rapidly-varying sinusoidal interference estimator. The rapidly-varying sinusoidal interference estimator is added to the unknown interference estimation loop to estimate rapidly-varying back EMF. And the frequency of the rapidly-varying sinusoidal interference estimator changes adaptively with the operating frequency of the motor to guarantee the desired estimation accuracy of back EMF in a wide-speed range. This design makes it possible to observe the back EMF in a relatively low bandwidth, thereby solving the tradeoff between LESO bandwidth and high-frequency noise filtering. Then, an enhanced phase-locked loop is presented to improve the ability of tracking the rapidly-changing speed. The effectiveness of the proposed method is verified at a 2.0-kW IPMSM sensorless drive. [ABSTRACT FROM AUTHOR]

Internal model control (IMC) has been used widely for its less computational burden, and simple implementation. By IMC, the disturbance including model mismatch, parameter variations, and other unstructured dynamic uncertainties cannot be eliminated effectively in the induction motor (IM) control system. To optimize the current-control performance of IM drives, a nonlinear current-control algorithm for the IM systems using IMC strategy based on a Luenberger disturbance observer (IMC-LDO) is proposed in this article. The time-varying disturbance has been considered in the IM system. Based on this system, the proposed method is derived, where a LDO is introduced to estimate the disturbance. To tune the proposed scheme properly, a stability analysis based on Jury criterion has been used to determine the selection of the observer gain. Comparative experimental results indicate that the proposed method improves the dynamic property and the robustness in case of parameter variations and step load change. The feasibility and effectiveness of the proposed method are verified by the experimental results. [ABSTRACT FROM AUTHOR]

The conventional model predictive torque control (MPTC) for induction motor drives evaluates the electromagnetic torque and stator flux linkage in the cost function. However, in the speed outer loop design, the torque reference in the cost function generally utilizes a classic proportional-integral (PI) controller, which is not only dependent on motor parameters but also sensitive to the change of the load torque. In this article, an adaptive sliding-mode-control-based MPTC (ASMC-MPTC) method is proposed to improve the robustness of the finite control set model predictive control (FCS-MPC). First, the influence of the mismatched parameters for FCS-MPTC is introduced and the shortcoming of the PI-based MPTC (PI-MPTC) is analyzed. Then, a sliding-mode-control-based MPTC (SMC-MPTC) is studied, in which the exponential reaching law is introduced to control the trajectories of the state variables. To further improve the control performance of SMC-MPTC, the exponential reaching law is optimized to adjust the switching gain adaptively, thus the ASMC-MPTC is proposed. The PI-MPTC, SMC-MPTC, and ASMC-MPTC are compared theoretically and experimentally, and the results show that the proposed ASMC-MPTC has the best disturbance rejection ability and robustness against motor parameters variation and load torque change. [ABSTRACT FROM AUTHOR]

A speed estimation method for induction motors (IMs) based on active disturbance rejection observer (ADRO) is proposed in this article, in order to realize the sensor-less control of IMs. Benefit from the antidisturbance mechanism of ADRO, the exogenous disturbance can be estimated instantaneously, so that ADRO can realize the disturbance estimation accurately without the knowledge of the exact system parameters. Meanwhile, ADRO copes with the unmodeling dynamics as well as the system uncertainties in the model parameters, so that it is robust to the external disturbances and the model errors. Meanwhile, the disturbance including the rotor speed information is estimated online by ADRO, and the rotor speed is estimated from the observed disturbance variation. The experimental results indicate that the speed estimation is feasible and effective. [ABSTRACT FROM AUTHOR]

A novel sliding mode observer (SMO) with optimized constant rate reaching law for speed estimation in sensorless induction motor drives is proposed in this article to balance the dilemma between the requirement of fast reaching transient and the chattering reduction on sliding mode surface. By considering the reaching way to the sliding mode surface, a widely used reaching law called constant rate reaching law (CRRL) is introduced into SMO. However, SMO with CRRL cannot satisfy the rapidity of transient performance and the low chattering level simultaneously. To solve this problem, an optimized constant rate reaching law (OCRRL), which is based on the options of an exponential term that adapts to the variations of sliding mode surface and system states, is introduced into SMO. The proposed SMO with OCRRL is able to decrease the reaching time and suppress the chattering problem simultaneously. Simulation and experimental results both show the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

A high-frequency (HF) voltage injection method can accurately estimate the rotor position of an interior permanent magnet synchronous motor at low speed. However, the fixed injection frequency for the traditional HF voltage injection method will produce a loud audible noise that limits the actual application of HF voltage injection method. In order to reduce the audible noise, a novel HF square-wave voltage injection method with the random switching frequency is proposed in this article. The frequency of the injected HF voltage varies with the random switching frequency, so it can effectively spread power spectrum caused by HF current and pulsewidth modulation (PWM), which will effectively reduce the audible noise caused by the HF current and PWM. Additionally, the power spectral density of the HF current based on the proposed method is analyzed to verify the effectiveness in reducing audible noise. Then, a corresponding demodulation method for induced HF current is presented. Finally, the experimental results show that the proposed method has continuous spectra and the audible noises can be suppressed significantly. [ABSTRACT FROM AUTHOR]

The conventional internal model control (IMC) has been used widely due to its advantages of less computational burden and simple implementation. Since the internal model controller has a fixed filter, disturbances created by mismatched models, parameter variations and other unstructured dynamic uncertainties in induction motors (IMs) cannot be eliminated by a fixed IMC. To solve these problems, the control strategy of an induction motor using internal model control with an extended state observer (IMC-ESO) was proposed. IM parameter variations and other unstructured dynamic uncertainties are considered in IM drives. Based on this model, an ESO is defined as a hypothetical equivocal function. Then the estimated disturbance is applied as a feed-forward compensation to accurately control the current loop. Since the designed ESO works concurrently with IMC, the fast dynamic response of the IMC is maintained. The feasibility and validity of the proposed method are validated by experimental results. [ABSTRACT FROM AUTHOR]

In this paper, to improve the robustness and realize the precision positioning as well as speed control of the servo drive system, an integrated sliding-mode control (ISMC) optimized by differential evolution (DE-ISMC) algorithm is proposed. ISMC guarantees that a motor can reach at given position with given speed, and given speed is set first. ISMC, which is combined with speed regulator and position regulator, is different from the conventional sliding-mode control (SMC) replacing speed regulator. ISMC can guarantee that motor speed is controlled under position control mode, which is a novelty and an advantage of ISMC in this paper. To achieve good control performance of ISMC, parameters of it should be chosen exactly, so DE algorithm is selected to optimize them. The most significant influence factor of DE algorithm is the optimization iteration. Once parameters of ISMC are optimized under convergent iteration, servo system performance reaches given indices in the shortest time. Experimental results indicate that robustness of the servo system is improved; correctness and effectiveness of DE-ISMC are verified. [ABSTRACT FROM AUTHOR]

An active disturbance rejection control (ADRC) of induction motor based on an adaptive particle swarm optimization (APSO) algorithm is proposed in this paper, in order to realize the precise decoupling of induction motor and the disturbance compensation. The novel control method employs APSO as the automatic tune mechanism for ADRC controller. According to the feedback information of induction motor, an optimal solution can be achieved via the optimization mechanism and self-learning ability of APSO, so the reliance of ADRC controller on parameters can be reduced. In order to obtain the better optimization solution more efficient, the aggregation degree and the evolution speed are introduced into the APSO to dynamically modify the inertia weight based on the practical optimization process. Experimental results indicate that the robustness of the proposed optimal design method for ADRC is better than the conventional ADRC when the disturbances occur, and the method is feasible and effective. [ABSTRACT FROM AUTHOR]

An autodisturbance-rejection control (ADRC) of an induction motor based on an ant colony optimization (ACO) algorithm is proposed in this paper, in order to realize the precise decoupling of the induction motor and the disturbance compensation. A novel control method employs ACO as an automatic tune mechanism for an ADRC controller. According to the feedback information from the induction motor, an optimal solution can be achieved via the optimization mechanism and self-learning ability of ACO after the iterative calculation; therefore, the reliance of the ADRC controller on parameters can be reduced. The simulation and experimental results indicate that the robustness of the proposed optimal design method for ADRC is better than that of the conventional ADRC when the disturbances occur and that the method is feasible and effective. [ABSTRACT FROM AUTHOR]

To improve the performance of sensorless induction motor (IM) drives, an adaptive speed and flux estimation method based on the multiple-model extended Kalman filter (EKF) with Markov chain for IMs is proposed in this paper. In this algorithm, the multiple model EKF for speed and flux estimation is established, and the transition of the models obeys the Markov chain and the estimation value is obtained by mixing the outputs of different models in different weightings, and the calculation of the weighting is researched. Simultaneously, the transition probability can be continuously self-tuned by the residual sequence, the prior information is modified by the posterior information, and the more accurate transition among the models is obtained. Therefore, the proposed method improves the model adaptability to the actual systems and the environmental variations, and reduces the speed estimation error. The correctness and the effectiveness of the proposed method are verified by the simulation and experimental results. [ABSTRACT FROM PUBLISHER]

A speed and flux estimation method for induction motors (IMs) based on robust adaptive state observer is proposed in this paper as a modification of the adaptive state observer. The effect of gross errors on estimation accuracy of the adaptive state observer is analyzed. Whether the robust adaptive state observer can give better estimation performance and robust ability than traditional adaptive state observer for speed and flux estimation of IMs is discussed. Through the simulation and experiments, the speed estimated error and the flux fluctuation of robust adaptive state observer by gross external disturbance and internal estimated error is compared with traditional adaptive state observer. The simulation and experimental results show that the robust adaptive state observer has the better estimation performance of antigross error than traditional adaptive state observer. [ABSTRACT FROM PUBLISHER]

The internal model control (IMC) has been widely attended for its simple structure and easy realization. Its control performance has a relationship with the filter time constant directly, so that its application of high performance is influenced in the application of motor drive system. A novel method of two-degree-of-freedom (2DOF) IMC strategy of induction motors (IMs) using the immune algorithm (IA) is proposed in this paper. The IA is studied on the basis of the immune response system and the algorithm realization is analyzed. The IA is introduced into the 2DOF IMC, and the filter time constant adjustment online is realized by taking full advantage of the adaptivity of the IA. The simulation and experimental results verify the effectiveness of 2DOF IMC strategy of the IM using the IA. [ABSTRACT FROM PUBLISHER]

This study presents a novel switched reluctance machine (SRM) with modular E‐core stators and multi‐layer common rotors for high reliability applications. The stator is composed of six independent modular E‐cores with the windings wound around the yoke of the E‐cores. The rotor consists of three magnetically independent common rotors which are place in the same shaft without any angular shift. The equivalent magnetic circuit (EMC) models of this new SRM at the aligned and unaligned positions are described. To evaluate the motor performance, two types of analysis, namely, approximate simplified two‐dimensional (2D) model and 3D model finite‐element analysis (FEA) have been utilised. The 2D FEA static and dynamic results are compared with 3D FEA results. Furthermore, comparisons between the novel modular SRM and a conventional 6/4 SRM are made. Finally, a prototype of this modular SRM has been fabricated and tested in the laboratory. Comparison between FEA and EMC analysis for flux linkage are made and compared with measured characteristics. The simulated and measured phase currents and average torque are also presented and compared to verify the analytical and simulation results. [ABSTRACT FROM AUTHOR]

Objectives: The position of sesamoid of thumb metacarpophalangeal (MCP) joint changed clearly when the joint was dislocated dorsally. However, the significance of sesamoid location in diagnosing joint dislocation was unclear. The present study aimed to explore the positional relationship between sesamoid bone and thumb metacarpophalangeal joint in normal and dorsal dislocation joints. Methods: Between January 2018 and August 2023, we collected 60 isometric plain films from sixty outpatients and reviewed 56 anisometric plain films from twenty‐eight emergency patients with dorsal dislocation of thumb MCP joint at Tianjin Hospital, then took measurements on the hand X‐ray images. The sesamoid length on its longitudinal axis was defined as DP, the distance between the distal edge of sesamoid and thumb MCP joint was defined as DJ, and the ratio of DJ and DP was R. An independent‐samples t‐test and paired‐samples t‐test was utilized to analyze difference among data groups. Results: The 60 isometric images were from 30 male and 30 female outpatients with normal bone structure in their hands, and the 56 anisometric images of the 28 emergency patients included both preoperative and postoperative materials. Among the outpatients, the actual distance between the distal edge of sesamoid and thumb MCP joint space (DJ) was 2.09 mm and 1.40 mm in males and females, respectively. The authentic average length of sesamoid (DP) was 4.46 mm in males and 4.22 mm in females. The average value of R (the ratio of DJ and DP) in males and females was 0.49 and 0.34, respectively. There were gender‐related statistical differences in DJ (p < 0.01) and R (p=0.01), but no statistical difference in DP (p > 0.05). For the 28 emergency patients, the mean value of R was –0.47 before joint reduction and 0.58 after joint reduction, with statistical difference between them (p < 0.01). Conclusions: There was significant difference in the relative position between sesamoid and thumb MCP joint when joint dislocation and joint reduction. The distal edge of sesamoid beyond thumb MCP joint could be an evidence in diagnosing joint dorsal dislocation. The distal edge of sesamoid below thumb MCP joint could be an evidence of joint reduction. [ABSTRACT FROM AUTHOR]

Speed sensorless control systems with a full order adaptive observer of the permanent magnet synchronous motor (PMSM) have received wide attention due to their advantages of simple structure, easy implementation and strong universality. However, they are sensitive to the load disturbances, which affects the speed performance of the control system. To solve this problem, this paper presents a disturbance rejection speed sensorless control of PMSMs based on full order adaptive observer to improve robustness against load disturbances. A load disturbance observer (LDO) is used to observe load disturbances, which feed-forward compensates the q-axis current to reduce the speed drop and accelerate the recovery time. Experimental results show that the proposed method has better anti-interference capability than full order adaptive speed sensorless control under the same steady-state performance. [ABSTRACT FROM AUTHOR]

This paper presents a 12/8-pole, three-phase, modular-stator hybrid excitation switched reluctance machine (MSHSRM) assisted with permanent magnets (PMs) as well as its design consideration and performance evaluation. The basic operating principle is illustrated through a specific form of this machine, and the magnetic equivalent circuit model is built and analyzed. Then, the main parameters of the machine are optimized by the finite-element method. The static magnetic characteristics and dynamic performance of this novel machine are simulated and compared with other two SRMs, one is segmented 12/8 SRM without PM, and the other is the conventional 12/8 SRM with unsegmented structure. Finally, two motor prototypes, including one MSHSRM and one conventional SRM of the same size are manufactured. The static magnetic characteristic and dynamic operation of two motor drives are measured to confirm the predictions. The simulation and experimental results indicate that this MSHSRM has higher power and stronger load capacities than the conventional SRM in whole speed range with higher torque/power density and higher torque per ampere. [ABSTRACT FROM AUTHOR]

A switched reluctance motor (SRM) with 12/10 poles is investigated in this paper. Compared with the conventional SRMs with single mode, the machine is not only able to be worked as a six-phase motor but also could be used as a three-phase motor, which is thus named multimode SRM (MMSRM). The primary dimensions of the stator and rotor cores are calculated by considering it as a six-phase SRM with long magnetic paths, and the performances of three-phase mode with short magnetic paths are used to test the parameters. The arcs of stator and rotor pole are treated as the optimization objects to minimize torque ripple and copper loss per torque and maximize torque per ampere of the MMSRM. A function is selected to solve the multiobjective problem and the final values of arcs of stator and rotor pole are determined based on the results of finite-element method. The effects of arcs of stator and rotor pole on electromagnetic performances of MMSRM are discussed independently, and a prototype is manufactured to test the simulations. A good agreement between the simulated and measured results verifies the validity of the analytical method and results. [ABSTRACT FROM AUTHOR]