In this paper, a novel direct torque control (NDTC) scheme utilizing composite active vectors based on discrete duty ratio modulation method is presented for permanent magnet synchronous motor (PMSM) in industrial robot servo control system. The errors in the PMSM driven by conventional DTC (CDTC) are compensated by single active vector during each control period, leading to unsatisfied steady-state performance. To improve the operation performance of the industrial robot servo control system effectively, the errors in the PMSM are compensated independently in NDTC. Therefore, two active vectors should be applied to compensate flux error and torque error, respectively, namely flux active vector and torque active vector. In order to maintain the merit of the fast dynamic response in CDTC, the introduced active vectors should be selected from the fixed six active vectors supplied by a two-level voltage source inverter. To describe the scheme of NDTC clearly, the angle between the applied active vector and the stator flux linkage is used to represent the error compensational effect provided by the applied active vector, namely active angle. Additionally, the compensational effect is defined as active factor. Subsequently, the duty ratio value of the active vector applied time can be derived easily. To simplify the calculations of the duty ratio values, novel discrete calculation method for the active factor by hysteresis controllers is presented in this paper. The effectiveness of the proposed NDTC strategy is verified through the experimental results on a 100-W PMSM drive system.

To address the issue of system parameter variations during the operation of a maritime light vessel rudder permanent magnet synchronous motor (PMSM), an extended Kalman particle filter (EKPF) algorithm that combines a particle filter (PF) with an extended Kalman filter (EKF) is proposed in this paper. This approach enables the online identification of motor resistance and inductance. For highly nonlinear problems that are challenging for traditional methods such as Kalman filtering, this algorithm is typically a statistical and effective estimation method that usually yields good results. Firstly, a standard linear discrete parameter identification model is established for a PMSM. Secondly, the PF algorithm based on Bayesian state estimation as a foundation for subsequent research is derived. Thirdly, the advantages and limitations of the PF algorithm are analyzed, addressing issues such as sample degeneracy, by integrating it with the Kalman filtering algorithm. Specifically, the EKPF algorithm for online parameter identification is employed. Finally, the identification model within MATLAB/Simulink is constructed and the simulation studies are executed to ascertain the viability of our suggested algorithm. The outcomes from these simulations indicate that the proposed EKPF algorithm identifies resistance and inductance values both swiftly and precisely, markedly boosting the robustness and enhancing the control efficacy of the PMSM.

The active vector effects on torque and flux linkage are different in interior permanent magnet synchronous motor (IPMSM) systems at different times under direct torque control (DTC). These different effects may cause overcompensation or undercompensation to torque and flux linkage leading to large torque and flux linkage ripples in the IPMSM DTC systems. A novel duty ratio modulation strategy for the IPMSM DTC systems is presented, which considers these differences that are ignored in conventional duty ratio modulation strategies. The proposed duty ratio modulation strategy aims at minimizing torque ripple and flux linkage ripple, which makes sure that the control system can work in an optimum state. The active angle, the impact angle, the active factor, and the impact factor are first introduced. The active angel and the impact angle are used to get the active factor and the impact factor, respectively. Every sector is divided into five small sectors based on the impact angels, and then, a switching table is redesigned according to the small sectors division. Also, the vector selection rules for the redesigned switching table are described in details. Subsequently, an optimal duty ratio can be derived through the simplified duty ratio determination method. Finally, the effectiveness of the proposed novel modulation strategy is verified through the experimental results on a 100-W IPMSM drive system.

In this paper, a novel direct torque control (DTC) scheme based on composite active vectors modulation (CVM) is proposed for permanent magnet synchronous motor (PMSM). The precondition of the accurate compensations of torque error and flux linkage error is that the errors can be compensated fully during the entire control period. Therefore, the compensational effects of torque error and flux linkage error in different operating conditions of the PMSM are analyzed firstly, and then, the operating conditions of the PMSM are divided into three cases according to the error compensational effects. To bring the novel composite active vectors modulation strategy smoothly, the effect factors are used to represent the error compensational effects provided by the applied active vectors. The error compensational effects supplied by single active vector or synthetic voltage vector are analyzed while the PMSM is operated in three different operating conditions. The effectiveness of the proposed CVM-DTC is verified through the experimental results on a 100-W PMSM drive system.