Yanfei Cao

To fully exploit the high dynamic response potential of small-inertia permanent synchronous motors (PMSMs) in high-transmission-ratio joint modules, this paper proposes a low-latency speed-current control method. Firstly, based on the control delay characteristics of real-time digital systems in the driver and the accurate electromechanical discrete model of the PMSM, a deadbeat predictive speed-current control strategy with theoretic three-carrier-period delay tracking characteristics is designed. By calculating and feeding back the predicted torque during transient speed tacking, the method eliminates the latency typically incurred between speed and current tracking loops. Subsequently, to meet the requirements of load torque estimation and suppression of high-frequency noise introduced by increased speed sampling, an enhanced two-step state optimal estimation method based on Kalman filter is proposed. This method uses the predicted speed over two steps to calibrate the system's noise model and estimate the motor states and lumped disturbances, thereby achieving the low latency tracking and robust control of the motor speed. Experimental results demonstrate that the proposed method significantly improves the dynamic performance under different conditions and exhibits excellent steady-state performance and robustness, making it suitable for application in integrated small-inertia motor drive systems.

This paper proposes both forward and inverse design methods for the carbon fiber (CF) sleeve of high-speed permanent magnet machines (HSPMMs), utilizing winding process parameters as design parameters and aiming to determine the feasible region for these parameters based on a two-dimensional (2D) stress analytical model. First, an analytical model is established considering the rotor's 2D structure and integrates factors such as virtual interference fit, centrifugal force, thermal stress due to temperature differentials, and material anisotropy. Utilizing this model, the virtual interference of multiple layers of CF can be solved in conjunction with the winding process. Subsequent analysis reveals the distribution of extreme rotor stresses and derives the design constraints for CF sleeve parameter. Through parameter scanning, we perform an inverse solution to obtain the feasible region of sleeve parameters. To enhance design efficiency, we estimate the static interlayer stress of CF and quickly solve for the virtual interference of multiple layers, leading to a forward solution for the feasible region of sleeve parameters. Rotor failure analysis is then conducted. Subsequently, finite element method (FEM) is employed to verify the correctness and effectiveness of the two proposed design methods. Finally, a test rotor is fabricated and subjected to high-temperature overspeed testing. The rotor analytical model and the two sleeve parameter design methods presented in this paper offer advantages in terms of fast computation, high accuracy, clear directionality, and flexible application, making them suitable for rotor strength analysis and material selection and parameter design of CF sleeves in HSPMMs.

High-performance torque and position control of robots relies on the high-precision current tracking control of joint motors. Among various control methods, time delay control (TDC) has attracted growing interest due to its advantages such as low dependency on parameters, computational simplicity, and good tracking performance for both high- and low-frequency signals. However, existing TDC algorithms for current control lack specificity to robotic operating conditions, and the inherent time delay estimation (TDE) errors reduce the current tracking accuracy. Therefore, this paper proposes a discrete time delay control (DTDC) algorithm with TDE error compensation to achieve higher precision in current tracking control. Firstly, the key factors affecting the current tracking accuracy of joint motors are analyzed based on actual operating conditions. Then, a direct TDE error compensation method is designed from the perspective of gradient descent, and a new DTDC control law is derived based on this, with its stability rigorously proven. Next, the effectiveness of the proposed method is demonstrated through a comparative analysis of transfer functions. Additionally, the direct compensation characteristics of the proposed method are highlighted, followed by the parameter sensitivity analysis and tuning guidelines. Finally, experiments are conducted on a 3.1-kW surface-mounted motor platform and a robotic joint module platform to verify the effectiveness of the proposed DTDC method through comparative analysis.

Aiming at the problems of control gain mismatch and disturbance rejection in permanent magnet synchronous motor control system, this article proposes a variable control gain linear active disturbance rejection controller (VG-LADRC) with strong disturbance rejection ability and control gain adaptive function. This controller adopts a cascaded extended state observer. ESO1 is used to jointly estimate the system control gain and external disturbance, and ESO2 further compensates the residual disturbance on this basis, thus realizing hierarchical processing and coordinated suppression of disturbance observation. To enhance the adaptability of the controller to the change of control gain, this article designs a control gain adaptive law based on error feedback and integrates the motor dynamic information to construct an adaptive factor. Thus, the controller can improve the control gain convergence speed through multidimensional state perception and enhance its robustness under complex working conditions. Theoretical analysis shows that the VG-LADRC has excellent disturbance suppression performance in the range of low-frequency to medium–high frequency and exhibits strong robustness to control gain mismatch. Finally, dynamic tests are carried out to verify the control performance and engineering applicability of the proposed method.

Servo control systems exhibit strong coupling among multiple control parameters, posing dual challenges of efficiency and stability during optimization. Traditional parameter tuning strategies based on systematic optimization often face difficulties, such as the need for precise modeling, low optimization efficiency, high dependence on data, and structural intrusiveness. This letter rethinks the problem of strongly coupled multiparameter optimization from a feature extraction perspective and proposes a physics-constrained self-supervised optimization framework. By employing a biphase hierarchical encoder and an independent encoder structure, the framework extracts key control parameter features from the system to enable effective optimization of servo control parameters. Furthermore, the method incorporates prior feature knowledge for network preraining, significantly reducing reliance on real data. Experiments conducted under both PI and ADRC control structures demonstrate that the proposed approach achieves rapid error convergence, offering high optimization efficiency while maintaining the structure’s nonintrusiveness.

In this paper, a novel triple-degree-of-freedom sevenphase motor (TDOF-SPM) is proposed to improve traditional multi-motor systems, pursuing higher integration. The investigated motor belongs to the multi-mechanical port motor, which comprises a single set of seven-phase armature winding and three axially arranged permanent magnet rotors. The principle of decoupled operation for three rotors in the TDOF-SPM is revealed basing on the electrical pole changing (EPC) for the multi-phase motor. Thus, the basic topology of 14-slot 4/8/12-pole is constructed, which is also general for motors with other degree-offreedoms. Furthermore, to reduce the torque ripple induced by EPC, the flux modulation effect is introduced and the improved topology of 14-slot 88/92/96-pole is proposed. Accordingly, the improvement mechanism is analyzed, and the comparison between the improved topology and the basic one is carried out. Meanwhile, through the finite-element-analysis (FEA), EPC, flux modulation effect, and axial magnetic field decoupling for the TDOF-SPM are analyzed. Finally, the prototype of improved topology is fabricated and experimented to validate the FEA results and operation principle of the TDOF-SPM.

In the speed control system based on linear ESO, poles and zeros exhibit inherent coupling characteristics. The conventional pole placement method typically neglects the impact of zero placement on observer performance, thereby diminishing the contribution of zeros to disturbance suppression and restricts the potential for further performance improvement. To overcome this limitation, this paper proposes a novel ESO structure by simultaneously incorporating measured position and speed states. Specifically, the ESO error correction term is optimized as a weighted sum of the position and speed estimation errors, which introduces an additional degree of freedom for the independent configuration of zeros and poles. The proposed method expands the tuning flexibility of linear ESO, reveals the influence of zero placement on the dynamic and steady-state performance as well as the stability margins and enhances the disturbance suppression performance through the independent zeros configuration. Finally, comparative experimental results confirm that the proposed dual-error-correction ESO-based speed controller exhibits superior disturbance rejection performance compared with the conventional methods under the same pole placement conditions.

This study addresses the critical challenge of constant power control for large-scale wind energy conversion system under the combined effects of pitch actuator degradation and multiple disturbances. In the paper, a novel fault-tolerant control strategy based on error-based active rejection control (E-ADRC) is proposed. The approach incorporates a composite control architecture, comprising a disturbance rejection tracking loop and a fault-tolerant compensation loop. Within the tracking loop, an enhanced E-ADRC algorithm is suggested which not only retains the robustness and ease of implementation of traditional E-ADRC but also significantly improves the attenuation of low-frequency wind disturbances—the turbine’s primary disruption. The fault-tolerant compensation loop applies independent control signals, derived from pitch angle residuals, to each faulty actuator, mitigating the extra fault disturbances in rotor speed tracking dynamics. This dual-loop structure enables the turbine to restore high-stability power output after a fault. Furthermore, the fault-tolerant compensation mechanism ensures that, even in cases of part of the three actuators failure, the previously misaligned pitch angles are synchronized, effectively suppressing the detrimental aerodynamic imbalance and reducing adverse loads. The superiority of this approach in enhancing power output stability and reducing structure fatigue damage have been validated through a refined hardware-in-the-loop test.

Aiming at the problem of incorrect switching caused by speed estimation deviation during the sensorless starting process of high-speed brushless DC motors (BLDCM), this paper proposes a constant-current frequency-up acceleration starting method based on quasi-current source inverter (QCSI). This method controls the inductor current to keep constant so that the motor can be accelerated with constant torque and designs the acceleration step number to realize the self-synchronous operation switching of the motor. In addition, a commutation error compensation strategy considering voltage clamping is proposed for the high-speed BLDCM driven by QCSI. This strategy calculates the phase lead angle caused by diode voltage clamping, perfects the source of commutation error, and improves the accuracy of the commutation error model, so as to obtain more accurate commutation error compensation angle. Experimental results show that the proposed starting method can realize reliable three-stage starting of the motor, and the parameter design is simple and convenient for engineering applications. In addition, the proposed compensation strategy enables fast and accurate commutation correction for the motor under both dynamic and steady-state conditions. It also achieves phase synchronization between the motor's back electromotive force and phase current, thereby improving the torque-to-current ratio.