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The conventional model predictive control (MPC) of permanent magnet synchronous motor (PMSM) always has a complicated computational burden and large current or torque ripples, which result in deteriorated control performance and difficult to achieve practical operating conditions. To address those issues, this digest proposes an improved model predictive flux-linkage control (MPFC) strategy for PMSM without weight coefficients. The proposed scheme retains excellent control performance of MPC with simple calculation. Firstly, according to the mathematical model of PMSM, the prediction model of flux- linkage established. The relationship between flux linkage and selected voltage vector is analyzed and a new sector division solution is discussed. Then, the design and implementation of the improved MPFC scheme is presented. Finally, a comprehensive simulation test has been conducted to verify the effectiveness of the proposed scheme.

The negative input impedance with the constant power load causes dc-link voltage and current oscillations in the metro traction drive system (MTDS) and weakens the stability of the system. In this digest, a small signal model of the simplified equivalent circuit of the MTDS is established, and the oscillation mechanism is analyzed. This digest proposes an active damping method based on the virtual damping and pseudolinear enhanced phase-locked loop (PL-EPLL). The stabilization scheme is realized by three parts: 1) the estimation of the dc-link voltage variation; 2) the generation of damping power; and 3) generation of stator current command. The dc-link voltage variation is firstly estimated by the PL-EPLL. And damping power is achieved by virtual damping resister in series with line inductor. Based on the inverter power control, q-axis current is obtained. Simulation results show that the active damping method effectively suppresses dc–link oscillation and improves the stability of MTDS.

This paper constructs a model of inverter-induction motor (IM) vector control system based on linear time-periodic (LTP) theory. The basic contents of the LTP theory are firstly presented for illustrating basic modeling ideas. Compared to the traditional linear time-invariant (LTI) model, the LTP model considers the coupling effect between input and output signals. Afterward, the small signal model of the inverter-motor system is constructed, where the coordinate transformation and the effect of SVPWM have been taken into account. Moreover, the accuracy of the model has been verified according to signal reproducing and BODE diagram. Simulation results have confirmed the accuracy of LTP modeling of inverter-induction motor (IM) system and theoretical analysis of DC-link stability.

Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies.

An approach using morphological filter technique is proposed to determine the respiratory rhythm from the photoplethysmographic (PPG) signal. As the structuring elements of morphological filter have a decisive effect on the analysis result, in the study the structuring elements are determined by the individual heart rate adaptively. The procedure was tested on a group of healthy subjects. Compared with the reference respiratory signal from the transthoracic impedance measurement, the proposed method is an efficient tool to detect the respiratory rhythm from PPG signal. Furthermore, the low computational complexity of the algorithm may make it easy to be implemented on Microprogrammed Control Units (MCU) for real-time processing. More experimental data is necessary to improve the reliability and robustness of the algorithm.