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The load current of the new power system has significant characteristics on a wide dynamic range, which poses challenges to current sensing technologies. This paper proposes a magnetic-sensitive element based on NdFeB/Lead Zirconate Titanate (PZT) magnetoelectric composite materials, and further develops a magnetoelectric coupling current sensor. The sensor operates in torque mode, enabling the detection of both wide dynamic range alternating currents and weak alternating currents. Experimental studies show that the sensor achieved a power-frequency current detection sensitivity of 15.56 mV/A, a linear range of (0–120) A, and a detection limit of 153 μA. The results indicate that the sensor exhibits high sensitivity in alternating current (AC) current detection, and at power frequency, possesses both a wide dynamic range and the capability to detect weak currents. Therefore, it shows great application potential in scenarios such as wide dynamic range AC current measurement and weak current detection in power systems.

To enhance the dynamic performance and disturbance rejection capability of the permanent magnet synchronous motor speed control system, a novel speed control method based on a novel sliding mode control (NSMC) and load torque observer is proposed on the basis of model predictive current control (MPCC) with a sliding mode disturbance observer. First, on the basis of MPCC, the influence of parameters such as resistance, inductance, and flux linkage on MPCC is analyzed. To address the aggregated disturbance caused by parameter mismatches, a piecewise square-root switching function sliding mode disturbance observer (SMDO) is designed to enhance the robustness of the parameters. To address the poor dynamic performance and inadequate robustness resulting from the proportional-integral-controller (PI) velocity loop control in the MPCC, a novel NSMC velocity control method is proposed. This method utilizes the hyperbolic sine function and fractional-order integral sliding mode surface, resolving the dilemma faced by traditional slide mode controllers (SMC) in balancing fast response and reduced vibration. Additionally, to enhance the system’s disturbance rejection capability, a sliding mode torque observer (SMTO) is designed to continuously update the observed load torque value into the NSMC controller, achieving speed compensation control. Finally, through comparative experiments among the proportional integral controller (PI), SMC, NSMC, and NSMC + SMTO, the results indicate that the proposed NSMC + SMTO exhibits the best speed response, steady-state characteristics, and disturbance rejection capability.

The torque ripples of robotic permanent magnet synchronous motors (PMSMs) degrade motion smoothness and positioning accuracy of the system, while inevitable load transients in robotic tasks further complicate torque ripple attenuation. To address this issue, this paper develops an event-triggered torque ripple attenuation method that explicitly distinguishes torque ripple from dynamic load transients. First, a sliding-mode torque observer is constructed to obtain real-time torque information, whose stability is rigorously analyzed using a Lyapunov function. Second, frequency-selective torque ripple extraction schemes are proposed to accurately isolate steady-state high-frequency torque ripple from the estimated torque signal. In particular, two specially designed filtering structures are developed and compared, one of which is selected to preserve ripple-related frequency content during test, ensuring robust and accurate ripple identification under varying operating conditions in robotics. Third, a torque-ripple-regulation-based compensation strategy is used within a vector-controlled PMSM drive, in which the extracted torque ripple is processed by a dedicated ripple regulator to generate voltage compensation signals. This strategy achieves effective steady-state torque ripple attenuation with low implementation complexity, while avoiding performance degradation during dynamic load transients. Finally, experimental results are provided to validate the effectiveness of the proposed methods.

The torque mode is more suitable for the direct drive 6 degree of freedom (6-DOF) parallel mechanism than the speed mode that both dynamic coupling and current coupling among motors are easily solved, but its key parameters and dynamic characteristics have never been studied, which are important and are the goals of this paper. First the hydraulic system of the direct drive 6-DOF parallel mechanism is simplified. Then the transfer function of the direct drive hydraulic system with the torque mode is deduced together with that of the speed mode. Finally, comparative experiments are conducted. Results show that the dynamic characteristics of the system with the torque mode which are generally worse than those with the speed mode, are mainly determined by the parameters of the motor-pump second-order element of the transfer function composed of two under-damped second-order elements, proportion differentiation (PD) control strategy and dynamic pressure feedback (DPF) control strategy are useful for the system with the torque mode, but practical and effective methods are still needed.

Among electric vehicles, electric three-wheelers are mostly used by the general public for their daily transportation. Hence, it is very important to provide bulk production of electric three-wheelers with better features and lower cost. These days, brushless direct current motors are being replaced with permanent magnet synchronous motors because of their high torque production at low speeds and high efficiency. For the drive train control part of a permanent magnet synchronous motor drive, a field-oriented controller is better because of its independent torque and speed control. This controller provides two modes of operation: torque mode and speed mode. Currently, most researchers are concentrating on the speed mode of field-oriented controllers. However, in a real electric vehicle, torque mode is necessary to drive in any terrain. In this paper, the field-oriented control-based torque mode operation of a permanent magnet synchronous motor drive for an electric three-wheeler application is discussed and validated. Performance analyses of the two modes of operation and experimental validation of the torque mode are carried out. The hardware development of an electric three-wheeler with the torque mode of a field-oriented controller based permanent magnet synchronous motor drive is realized. Finally, paper is concluded with an economic analysis of the developed electric three-wheeler in comparison with an available internal combustion engine-based three-wheeler.

This study analyzed how different downward loads and rotational kinematics influence NiTi rotary instrumentation outcomes. Heat-treated NiTi instruments were used to prepare extracted human single-rooted premolars with a moderate canal curvature. Instrumentation was performed using an automated endodontic instrumentation device with controlled downward loading and torque/force sensing, under different downward load settings (1, 2, and 3 N), employing either continuous rotation (CR) or optimum torque reverse (OTR) motion, which is a torque-sensitive reciprocation. Instrumentation was completed without instrument fracture or ledge formation in all six groups. OTR-3N specimens displayed a significantly lower upward force (i.e., screw-in force) than OTR-2N specimens (p < 0.05). OTR-1N specimens required a significantly longer instrumentation time than CR-1N specimens and the other OTR specimens (p < 0.05). At 1 mm from the apex, CR-2N specimens showed a significantly larger canal-centering ratio (i.e., larger deviation) than OTR-2N specimens (p < 0.05). Overall, applying a downward load of 2–3 N in OTR mode provided shaping efficiency similar to CR, but with a reduced screw-in force and enhanced canal-centering in the apical region, supporting the use of OTR as a promising alternative to CR for curved canal preparation using heat-treated NiTi instruments.

A Linear Active Disturbance Rejection Control (LADRC) method with a Variable Gain Load Torque Sliding Mode Observer (VLTSMO) is proposed in this paper to reduce the effects of the load torque disturbance of Interior Permanent-Magnet Synchronous Motors (IPMSMs). First, the LADRC is used as a speed loop controller, and the linear extended state observer (LESO) is used to observe the total disturbance. Then the stability of the controller is analyzed. Second, the VLTSMO is proposed, which can output a feedforward compensation signal to improve the observation capability of the observer. In addition, after comparing several standard switching functions, the continuous switching function is selected to reduce the chattering phenomenon. Finally, a 5.5 kW IPMSM is taken as the research object. A simulation model and the dSPACE motor control platform are used to realize the algorithm. Both simulation and experimental results show that the VLTSMO has excellent observation capabilities. They also show that the LADRC + VLTSMO method can effectively improve the dynamic performance and robustness of the speed control system.

A new direct torque control method for three-level direct matrix converter permanent magnet synchronous motor (TLDMC-PMSM) based on the modulation coefficient optimization method (MCOM) is proposed to address the problems of large torque chain pulsation, amplitude disorder and weak system robustness in matrix converter permanent magnet synchronous motor system (MC-PMSM) using direct torque control (DTC). In the paper, firstly, the principle of MC-PMSM-DTC system is described; secondly, the two-level MC is replaced by TLDMC, the speed loop is cascade spiral sliding mode control, the torque magnetic chain loop is super twisting sliding mode control-direct torque control to replace the traditional PI control, and the modulation coefficient optimal method is introduced to reduce the drawback of gradually increasing motor torque fluctuation, and then the accurate control of PMSM is realized; finally, the feasibility and superiority of the proposed method are verified by MATLAB/Simulink simulation software and hardware experiments.

This study presents design and implementation of a dynamic electronic load controller (DELC) for voltage and frequency control of a three-phase self-excited induction generator (SEIG) driven by constant power unregulated small-hydro turbine. This DELC is a combination of insulated-gate bipolar transistor-based voltage sourced converter (VSC) and variable frequency drive (VFD) which is connected across the DC link of VSC. The VFD operates in direct torque control mode and is coupled with a pumping system. The DELC is connected at point of common coupling in parallel with consumer loads. The VSC provides instantaneous control of the SEIG voltage through reactive power compensation. The VFD consumes the power in excess of consumer loads to maintain constant generator output power which in turn regulates the frequency. The excess generated power consumed by the VFD is used to pump water either to an overhead tank or for irrigation purposes. The performance of the proposed DELC of SEIG is demonstrated under various types of loads such as linear/non-linear, balanced/unbalanced loads and so on. Test results recorded on a developed DELC of SEIG exhibit simultaneous voltage and frequency control capabilities of the DELC under varying loads.