Saturated Vectorial Control of Multi-phase Synchronous Motors

The bearingless synchronous reluctance motor (BSynRM) is a multi-variable, nonlinear and strong-coupled system. To solve the difficult problem of precise decoupling in electric torque and radial suspension force control, the theory of direct torque control of traditional synchronous reluctance motor are applied to the torque control of a BSynRM in this paper. Based on mathematical models of the BSynRM, A direct torque control algorithm based on space vector pulse width modulation (SVM-DTC) is deduced. The SVM-DTC control system is designed and simulated. The simulation results show the control algorithm of SVM-DTC realizes decoupling in electric torque and radial suspension force control. The static and dynamic performance of electric torque, speed and radial suspension force of the BSynRM is excellent.

We have proposed two different digital control methods, where the controlled variables are joint torque and joint angular velocity, of space robot manipulators using the transpose of Generalized Jacobian Matrix. These methods are developed in discrete time domain so that the stability of system can be guaranteed when digital computers are used as controllers. The relation between the two methods, however, is not reported, although the basic concepts of these methods ar similar. This paper presents a novel digital control method, which integrates joint torque control with joint velocity control, of nonredundant space robot manipulators using the transpose of Generalized Jacobian Matrix. The merit of this new control law is to be applicable to both joint's torque controller and joint's velocity controller by only tuning the controller gains. Furthermore, computer simulation of a 6-DOF space robot manipulator is performed. Simulation result demonstrates the effectiveness of the proposed method.

Deadbeat-direct torque and flux control (DB-DTFC) has been emerged as a high performance digital control law for induction machines and permanent magnet machines. Its key attributes are excellent dynamic performance, the use of only one single control law over a wide torque/speed range and direct applicability to overmodulation strategies. This paper extends prior research by presenting the implementation of DB-DTFC for synchronous reluctance machines (SynRMs). In addition, a control law for minimizing SynRM losses each switching period is proposed. Real-time implementation on a 5.5kW test bench is demonstrated.

A new instantaneous torque-control strategy is presented for high-performance control of a permanent magnet (PM) synchronous motor. In order to deal with the torque pulsating problem of a PM synchronous motor in a low-speed region, new torque estimation and control techniques are proposed. The linkage flux of a PM synchronous motor is estimated using a model reference adaptive system technique, and the developed torque is instantaneously controlled by the proposed torque controller combining a variable structure control (VSC) with a space-vector pulse-width modulation (PWM). The proposed control provides the advantage of reducing the torque pulsation caused by the nonsinusoidal flux distribution. This control strategy is applied to the high-torque PM synchronous motor drive system for direct-drive applications and implemented by using a software of the digital signal processor (DSP) TMS320C30. The simulations and experiments are carried out for this system, and the results demonstrate the effectiveness of the proposed control.

The paper presents a framework for the design and analysis of position observers for sensorless control of synchronous reluctance machines. An improved inductance model is developed to account for the position error induced inductance variations. The instability regions of active flux based position observer are analytically identified and validated. A novel technique, Adaptive Projection vector for Position error estimation (APP), that alleviates the stability problems is introduced. Furthermore, the proposed technique can be augmented with a second projection vector to estimate speed error independently of the position error, referred to as Adaptive Projection vector matrix for Position and Speed error estimation (APPS). Stability and performance of proposed technique is validated on a 1 kW synchronous reluctance motor test bench.

This paper examines the torque response based on direct torque control (DTC) for an interior permanent magnet synchronous motor (IPMSM). DTC with a PI controller for torque control is used in this study. The relationship between the gains of the PI controller and the torque response is derived based on the transfer function of the torque control loop. Also, this paper discusses the influence of the nonlinearity of the torque control loop on the torque response. In addition, this paper proposes a linearization method for the torque control loop based on gain scheduling, and improvement of torque response is achieved. The effectiveness of the proposed method is verified by both simulation and experimental results.

This paper presents the real-time speed control of permanent magnet synchronous machine (PMSM) in a motoring mode for variable speed wind energy conversion system application. For this purpose, a discrete real-time laboratory test-rig is prepared using Permanent magnet synchronous servo motor, GUASCH Inverter and Texas instrument TMS320F28069 Digital Signal Processor (DSP) discrete real time microcontroller control card in a GUASCH board for implementing the designed PI current controller and PI speed controller. In addition, a simulation model of the system is prepared in MATLAB Simulink user-defined function blocks considering the dynamic mathematical equations of every part in the system. Finally, the achieved results of test-rig show that the system works very well for different transient speed changes. Moreover, it shows that the real-time time results validate the MATLAB simulation model results of the system.

High-precision torque estimation and control of induction motor drives is an important research field due to the extensive use of these motors in torque controlled applications, for example, in electric vehicles. The open-loop torque control performance depends strongly on the accuracy of both the motor model and the flux estimation. To address this appropriately, an adaptive Kalman filter with offline parameter and observer design optimization is proposed in this article. Thereby, the basic induction motor model is extended by magnetic saturation, iron losses, and skin effect influences. All uncertain motor model and observer configuration parameters are offline identified by a global optimization technique, namely particle swarm optimization. The identification utilizes a comprehensive data set consisting of test bench measurements and leads to an optimized observer enabling precise torque estimation and control. In experimental validation, for both torque estimation and control, the root-mean-square error is below 1 % of the nominal torque over the entire operating range. With the help of an accurate gray-box inverter model for phase voltage estimation and a speed-adaptive Kalman filter tuning scheme, the proposed observer is able to operate also at slow speeds including standstill.

The interest for multiphase permanent magnet synchronous machines, in modern renewable power generation systems, is increasing rapidly due principally to their high efficiency and fault-tolerant capability. To meet the high-performance requirements, monitoring the stator winding state is a key item. The detectability of a stator winding inter-turn short-circuit (ITSC), for an asymmetrical six-phase surface-mounted permanent magnet synchronous motor, is analysed in this study. The impact of an ITSC on the stator back-emfs, stator currents and voltages is examined by spectral analysis of the corresponding space-vectors, in different α–β planes. In particular, the detectability of a stator ITSC, in closed-loop operating conditions, is investigated using voltage and current signature analysis. The spectral fault signature is identified through 2D finite element analysis, and then confirmed by laboratory experimental tests.

This article considers an adaptive control scheme previously developed for region 2 control of a variable speed wind turbine. In this paper, the question of theoretical stability of the torque controller is addressed, showing that the rotor speed is asymptotically stable under the torque control law in the constant wind speed input case and L/sub 2/ stable with respect to time-varying wind input. Further, a method is derived for selecting /spl gamma//sub /spl Delta/M/ in the gain adaptation law to guarantee convergence of the adaptive gain M to its optimal value M*.

Nonlinear Attitude Control for Large and Fast Maneuvers

This article reviews the state-of-the-art back electromotive force (EMF) based sensorless schemes for synchronous machines. Field-oriented control (FOC) of a synchronous machine requires real-time rotor position for decoupled torque and flux control. Extraction of rotor position without a sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods have not been thoroughly investigated and documented. This article first reviews basic sensorless methods. The two implementation forms of an observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer a few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this article.

A general approach to torque and flux control of an induction motor fed by a voltage-source inverter is described in this paper. It is independent of whether rotor or stator flux is controlled. Based on this, an algorithm can be set up which allows the generation of the inverter switching patterns as a function of the reference values, both of the electromagnetic torque and of the controlled flux. Experimental comparisons with traditional direct torque control and field-oriented control techniques confirm the possibility of achieving very high dynamic performance with the proposed strategy.

Conventional direct torque control (DTC) achieves faster dynamic response compared to field-oriented control in permanent magnet synchronous motor drives (PMSM). However, it usually features large torque and stator flux ripple which deteriorates the steady performance of PSM drive. Various duty- based DTC schemes have been proposed to reduce torque ripple at the expense of increased complexity and parameter dependent. According to the perspective of flux vectors and load angle, a simple yet efficient method is proposed to calculate the duty ratio of active vector. The proposed scheme is able to reduce torque ripple significantly and is insensitive to variations in PMSM parameters, while the inherent merits of the conventional DTC, e.g., fast transient performance and simple control structure, are maintained. Simulations results are provided to confirm the valid of the proposed method.

Because traditional direct torque control (DTC) has unfixed switching frequency and ripple of torque and flux, deadbeat direct torque and flux control (DB-DTFC) of interior permanent magnet synchronous motor (IPMSM) is studied. At first, DB-DTFC based on IPMSM mathematical model is deduced. The calculated proper voltage vector can make reference torque and stator flux during one sampling period. But, parameters of IPMSM such as inductance of stator windings vary with its operation and affect on torque and flux performance. Secondly, parameter identification based on recursive least squares with forgetting factor is analyzed, which can identify IPMSM parameters online and eliminate their affects on performance of torque and stator flux. Finally, simulations are carried out and validate the proposed DB-DTFC which has both excellent dynamic and steady performance.