This paper deals with the high accurate current set-points solution for Interior Permanent-Magnet Synchronous Motors (IPMSM) in wide-speed range applications. Considering voltage and current constraints, the operating regions can be divided into Maximum Torque Per Ampere (MTPA), Maximum Current (MC), Field Weakening (FW) and Maximum Torque Per Voltage (MTPV) regions, which requires to solve different non-linear functions in real time to obtain optimal current set-points. Traditional methods including curve-fitting methods and polynomial approximation (PA) methods are not easy to obtain these solutions, especially involving magnetic saturation problems. In this paper, Newton- Raphson (N-R) algorithm for improving the control accuracy of the current set-points is proposed. Meanwhile, parameters influence including magnetic saturation and resistive voltage drop is fully investigated. Compared with PA method, the proposed method is able to converge to accurate solutions in few numbers of iterations with reduced execution time, which can be easily implemented on an off-the-shelf Digital Signal Processor (DSP). Both simulation results and experimental results on an 8kW IPMSM rig are conducted showing good agreement with the expected results.

The magnetic levitation technology has attracted blooming attention from all walks of life thanks to its superiorities such as noncontact and active control. While the intrinsic features of open-loop instability and strong nonlinearity, along with the uncertain external disturbance make the levitation control particularly significant and difficult. For speeding up the convergence and obtaining a better stability and disturbance robustness, this article proposes an ultralocal model-free adaptive supertwisting nonsingular terminal sliding mode control strategy for the magnetic levitation system. Different from the conventional model-based control, ultralocal model-free control breaks the constraint of a precise system model. Therefore, an improved second-order ultralocal model is established for the magnetic levitation system. For the benefit of finite time convergence and nonsingularity, the nonsingular terminal sliding mode surface is chosen. As a second-order algorithm, supertwisting (ST) algorithm can fundamentally suppress the chattering effect of the sliding mode control. An adaptive ST algorithm is designed for the further improvement of the system dynamic response. The stability of the proposed scheme is strictly verified based on the Lyapunov stability theory. Simulation and experimental comparisons with the existing control methods validate the exceeding performance of the proposed strategy under various operating conditions.

This article proposes an adaptive model predictive current control (AM-MPCC) for surface-mounted permanent magnet linear synchronous motor systems to simultaneously enhance the robustness against permanent magnet flux, inductance, and resistance mismatches. First, the conventional continuous control set model predictive control is analyzed, illustrating that parameter variations will inevitably deteriorate the current regulation performance. Then, an adaptive predictive model, which involves a disturbance term and an optimized current change rate coefficient, is proposed. The optimal coefficient is estimated using a steady-state incremental model and the steepest descent method at each control period. A discrete-time sliding mode disturbance observer is devised based on the adaptive model with updated coefficients to achieve the disturbance term. Finally, an exponential reaching law-based-reference trajectory is defined for the cost function of AM-MPCC to adjust the current approach trajectory. Experimental results verify the excellent robustness performances of the proposed method.

In this paper, a cost-effective and highly accurate resolver-to-digital conversion (RDC) method is presented. The core of the idea is to apply a third-order rational fraction polynomial approximation (TRFPA) for the conversion of sinusoidal signals into the pseudo linear signals, which are extended to the range 0-360° in four quadrants. Then, the polynomial least squares method (PLSM) is used to achieve compensation to acquire the final angles. The presented method shows better performance in terms of accuracy and rapidity compared with the commercial available techniques in simulation results. This paper describes the implementation details of the proposed method and the way to incorporate it in digital signal processor (DSP) based permanent magnet synchronous motor (PMSM) drive system. Experimental tests under different conditions are carried out to verify the effectiveness for the proposed method. The obtained maximum error is about 0.0014° over 0-360°, which can usually be ignored in most industrial applications.

CLIC4/mtCLIC (referred to here as CLIC4) is one of the seven-member family of chloride intracellular channels (CLIC). CLIC4 localizes to the mitochondria, nucleus, cytoplasm and other organellular compartments and participates in the apoptotic response to stress. However, the role of CLIC4 in oxidative stress and apoptosis is not well understood. In this study, we showed the important role of CLIC4 in apoptosis of C6 glioma cells induced by hydrogen peroxide (H2O2). Our results showed that CLIC4 protein expression was upregulated following H2O2-induced C6 cell apoptosis. The upregulation of CLIC4 protein expression was paralleled with an increased Bax/Bcl-2 ratio, cytochrome c and cleaved caspase-3 protein expression upon H2O2-induced C6 cell apoptosis. Suppression of CLIC4 expression by RNA interference enhanced cell apoptosis, but the ratio of Bax/Bcl-2 was not involved in this process. Dissipation of mitochondrial membrane potential and nuclear translocation of CLIC4 were involved in the activation of apoptosis induced by H2O2. Our data indicate that CLIC4 protein may be a key element in the apoptotic response to oxidative stress.

This paper investigates the stability of LCL-filtered grid-connected inverters with capacitor current feedback (CCF) active damping. The impact of time delays in the digital controller on active damping and its equivalent virtual impedance is analyzed. The inherent relationship between these time delays and stability is illustrated. Specially, a critical value of the CCF active damping coefficient k _{damp_c} is proposed to define three distinct regions of stability evaluation. If k _{damp_c} > 0, a sufficient but smaller damping coefficient (k _damp < k _{damp_c}) is recommended as optimum damping solution; if k _{damp_c} = 0, system will be unstable irrespective of active damping; and if k _{damp_c} < 0, active damping is not necessary to design a stable system. Necessary conditions to ensure stability are identified; guidelines for controller design are then presented to optimize the performance of active damping and dynamic response. Simulation and experimental results confirm the presented analysis.