Direct torque control with space vector modulation (DTC-SVM IntroductionDirect torque control with space vector modulation is a modification of the original direct torque control (DTC) method [1][2][3]. The excellent dynamic torque-control capabilities of traditional DTC are well known in the literature for permanent magnet synchronous motors and for other motor types as well [4][5][6][7][8][9]. However, there are serious disadvantages and among them the most important are: varying switching frequency and the excessive amount of torque-ripple generated [10][11][12]. DTC-SVM solves these problems, as it uses fixed switching frequency and the torque-ripple is significantly reduced compared to DTC, while the dynamics of the torque-control is essentially identical to that of traditional DTC [13][14][15]. Therefore, DTC-SVM is currently considered as one of the most promising alternatives of the nowadays widely used field-oriented control [16,17].DTC-SVM was introduced in [1][2][3]. These publications highlighted the main advantages of DTC-SVM. Since then many investigations have been carried out for this method. Special applications requiring high dynamic performance, excellent efficiency and high precision have been examined such as artillery speed servo systems [18], electric vehicles [19], electric pitch servo systems for wind generators [20]. Also, asymmetric permanent magnet synchronous machines have been investigated and special solutions have been invented for these machines [21]. In order to improve the performance of DTC-SVM several modifications have been developed. Most of the modifications aim at reducing the torque-ripple, increasing the dynamic performance and the efficiency of the method [22][23][24][25][26][27][28]. Sensorless methods using extended Kalman-filter have also been invented [29].However, the overload-capabilities of DTC-SVM and its stability during overloading have not been investigated yet. This article deals with these issues and suggests a modified DTC-SVM (MDTC-SVM) method which has significantly improved overload-capabilities and it is stable during overloading.

Optimum performance of switched reluctance motors (SRMs) over a wide range of speed control is an essential approach for many industrial applications. However, the doubly salient structure and deep magnetic saturation make magnetization characteristics of SRMs a highly nonlinear function of rotor position and current magnitude. This, in turn, makes the control of SRM drives a challenging task. As the control of SRMs depends on the inductance profile, it requires an adaptive control technique for optimum operation over a wide range of operating speeds. This paper presents an adaptive control technique for optimum excitation of SRM drives. The proposed control technique accurately considers the effect of back-emf voltage for high-and even low-speed operation. It determines the most efficient switch-on angle as a function of motor speed and current magnitude. Moreover, the optimum switch-off angle is defined to enhance motor output torque/power without negative torque production. The proposed technique simplifies the SRM control in order to cut down the complexity and cost; it offers easy implementation and can be used for sensor and sensorless operation of SRM drives. It also provides an eligible candidate for industrial applications as the optimization strategy uses an analytical solution. For adequate modeling, the nonlinear magnetization characteristics of the SRM are obtained using finite element analysis. The SRM, converter, and control algorithm are modeled using the MATLAB/Simulink environment. The simulation results are compared with a closed-loop switch-on angle controller in order to show the feasibility of the proposed control technique. In addition, experimental results are obtained to prove the promising performance and simplicity of the proposed controller.

High performance control and analysis of switched reluctance machines (SRMs) require accurate modeling of their magnetic characteristics. However, the doubly salient structure and deep magnetic saturation make it very complicated to accurately model SRMs. This paper presents a high fidelity model development for SRMs. The model is developed based on the experimental measurement of flux-linkage and torque characteristics. The introduced measurement noises / errors are investigated carefully. Then several post-processes are achieved to reduce these noises. The measurement accuracy is verified by three methods: finite element method (FEM), search coil comparison, and LCR meter. The measured data are employed after proper rearrangement to build a dynamic MATLAB simulation model for the tested 8/6 machine. The model accuracy and dependability is achieved experimentally.

Synchronous reluctance motor drives are one of the most attractive alternatives of permanent magnet synchronous motor drives and induction motor drives in the field of conventional industrial and household applications. This tendency is expected to be continued in the case of motion control applications as well. This article investigates two torque-control algorithms that are possible candidates for motion control synchronous reluctance motor applications. The examined torque-control algorithms are direct torque control (DTC) and hysteresis current vector control (HCVC).

No abstract