This paper proposes a sensorless control scheme for synchronous reluctance (SyR) motor drives based on the direct-flux vector control (DFVC) method. The control operates in stator-fluxoriented coordinates, using constant switching frequency. A hybrid position and speed observer is proposed, based on the combination of the active flux concept and high-frequency signal injection and demodulation. The two methods are fused together to form a unique position and speed estimate signals, with seamless transition between the two models based on reference speed. The proposed observer covers a wide speed range, from standstill operation at full load to flux weakening (FW). Furthermore, it is inherently immune from position estimation error caused by cross saturation, as proven mathematically and experimentally. The motor is operated according to the maximum torque per ampere (MTPA) law. Specific issues related to MTPA around zero torque are addressed in this paper. The proposed control technique extends the range of application of the DFVC to encoderless drives, and can be usefully adopted in those applications where both zero-speed and FW speed range operations are necessary, such as home appliances, or automotive and aerospace actuators and generators. A 2.2-kW SyR motor prototype was tested to verify the feasibility of the proposed method. Key tuning aspects are addressed in this paper.

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In this paper, a direct power control (DPC) technique is proposed for matrix converter-fed grid-connected doubly fed induction generators (DFIGs). In contrast to what has been investigated in the past for direct torque control (DTC) or DPC of matrix converter-fed DFIGs, the active and reactive powers are regulated in a fixed switching frequency using indirect space vector modulation (ISVM) technique. Hence, designing input filters for matrix converters (MCs) becomes convenient. In addition, the reactive component of input side of MC is controlled which leads to reduction of distortion in grid current waveform. Also, an extensive discussion is addressed for nonlinear voltage errors of MC that may cause inaccurate power control. Simulation results done in MATLAB/Simulink show the effectiveness of the proposed method.

This paper proposes a sensorless direct flux vector control scheme for synchronous reluctance motor drives. The proposed controller operates in stator flux oriented coordinates, regulating in closed-loop the amplitude of stator flux linkage and the current component quadrature to flux vector, at constant switching frequency. A hybrid position and speed observer is proposed, covering a wide speed range, based on backelectromotive force (EMF) integration and augmented at zero and low speed levels by high-frequency signal injection. Crosssaturation position estimation error is inherently compensated by the proposed observer scheme. Various experimental results for a 2.2-kW synchronous reluctance motor are presented to verify the feasibility of the proposed method.

Summary In this paper an efficient algorithm for simultaneous scheduling of energy and primary reserve with the presence of smart electric vehicles in the system is discussed. It is proposed that the system operator uses the electric vehicles (EVs) as alternative resources of primary reserve in the power system. The proposed model deals with the effect of generation scheduling on the EV charging schedules and primary reserve capacities. In fact, the amount of primary reserve provided by EVs is highly related to the EV's charging schedules. Therefore, in this paper a smart charging algorithm is also proposed that is based on direct load control of EVs by the system operator. The proposed scheme would be applicable with the lowest intelligence level and will not impose extra investment cost to the EV owners. All the nonlinear constraints included in the primary reserve scheduling are linearized to be solvable by mixed integer linear programming method. A case study on IEEE RTS79 system with 30% EV penetration is used to illustrate the feasibility and acceptable performance of the proposed method. The influence of EVs' participation on operation costs, load curve, and EV bills is discussed.

Matrix converter nonlinear errors due to voltage drop and commutation delay introduce a distortion between voltage reference signals and output phase voltages. In current controlled applications, the current regulators are capable of compensating for such voltage command error. However, where output voltage estimation is required such as in state observers used for sensorless control of ac drives, the converter error reduces the accuracy of the voltage estimate, especially at low speeds. This work proposes a simple and accurate technique for the identification of converter parameters before the drive startup. Based on the identified parameters, the nonlinearities are compensated. The feasibility and effectiveness of the presented method is shown in simulation. Experimental results are also reported.

The compensation of converters' nonlinear voltage error is crucial in encoder-less control of ac motor drives. In this paper, a new self-commissioning and compensation method is proposed for matrix converters (MC). Similar to what done in the past for voltage source inverters, the MC voltage error is identified before the drive start and stored in a look-up table (LUT), later used for error compensation and accurate voltage estimate. Different from what observed in the past, the effect of parasitic capacitors on nonlinear voltage error of MCs in four-step current based commutation is observed and studied. Eventually, this method is applied to the sensorless control of a synchronous reluctance (SyR) motor drive, using the direct flux vector control (DFVC) concept. Experimental results are presented to validate the effectiveness of proposed self-commissioning in improving the performance of sensorless control at standstill and low speed.