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A finite-time control scheme for autonomous body-fixed hovering of a rigid spacecraft over a tumbling asteroid is presented. The relative configuration between the spacecraft and asteroid is described in terms of exponential coordinates on the Lie group SE(3), which is the configuration space for the spacecraft. With a Lyapunov stability analysis, the finite-time convergence of the proposed control...
The snag in a DTC scheme based induction motors is the presence of high content of torque ripples in the output torque. This has been reduced by modifying the three-level torque controller to five-level torque controller. Moreover, the controllability of the torque in motor with no overshoot and minimal ripples, good transient and steady state responses forms the basis of performance analysis. This...
Direct torque control (DTC) of an induction motor fed by a two-level voltage source inverter (VSI) is a simple scheme that need less computation time, can be implemented without mechanical speed sensors and is insensitive to parameter variations. In principle, the motor terminal voltages and currents are sampled and used to estimate the motor flux and torque. Based on estimates of the flux position...
Direct Torque Control (DTC) of induction motor is a scalar control technique that gives excellent torque dynamic performance. Deriving the advantages of multilevel inverter, a modified DTC is proposed in this paper for the induction motor, driven by a cascaded three-level inverter. The proposed DTC gives superior torque performance compared to the use of Field Oriented Control (FOC) under transient...
This paper presents an AC drive system based on six-phase machine with three neutrals. The machine side converter has nine power legs and can be connected to the grid through one single DC-link or three isolated DC-links. Compared with the conventional back-to-back AC six-phase machine drive system, the proposed drive system permits reducing the DC-link voltages, eliminating step-up transformer, and...
Model Predictive Control (MPC) includes a mathematical model of the controlled system. Based on this model optimal actuating variables for future timesteps are determined in every sampling step. Thus the MPC exhibits a better response to a setpoint step compared to conventional control. In this paper a Model Predictive Control method for nonlinear systems with inherent output saturation is presented...
This paper presents the torque ripple reduction in the direct torque controlled (DTC) five phase induction motor (IM). The ripples are directly related to the hysteresis band of the controller in torque and flux loops within the operating switching frequency limits. It is proposed to increase the switching frequency by dither signal injection into the torque and flux control loops. A conventional...
Classical Direct Torque Control (DTC) exhibits high dynamic response due to inherent hysteresis controllers, but suffers from the issue of variable switching frequency. This paper proposes a DTC technique that is not only able to retain the dynamic response of classical DTC, but also achieves both constant switching frequency as well as lesser torque and flux ripples compared to classical DTC. Comparison...
In this paper a single-stage solar Photo Voltaic (PV) system feeding the power to an Open-End Winding Induction Motor (OEWIM) via a dual-inverter is presented. The OEWIM is coupled to a centrifugal pump for water pumping application. The dual-inverter fed OEWIM is chosen, as it requires low debus voltage which helps in optimal arrangement of PV modules, which could avoid large strings. In the proposed...
This paper deals with motion control of the inertia wheel pendulum. Specifically, we address a trajectory tracking problem. The proposed control algorithm is derived from feedback linearization, with the output of the system defined as the tracking error between a desired reference trajectory and the angular position of the inverted pendulum. The explicit expressions of the internal dynamics and zero-dynamics...
This paper presents a novel method for controlling a dual arm robot to pick heavy objects. The motivation for this study is inspired from the observation of human motion in their daily activities. Two reflex actions are proposed in this work. The first reflex is designed to control the COM of the robot when its stability is endangered by the effect of the object weight. Static stability criterion...
Permanent magnet synchronous motor (PMSM) are favored in traction drives of rail vehicles for their high efficiency of operation. Traction inverters always operate at reduced switching frequency to minimize the losses in semiconductor devices. To restrain the motor current harmonics, off-lined calculated optimal synchronous pulse patterns can be used. This paper presents a closed-loop control of permanent...
A voltage source inverter-fed synchronous magnet synchronous motor (PMSM) produces torque ripple due to application of pulsewidth modulation (PWM) method. Torque ripple is influenced strongly by the PWM strategy. A Hybrid SVPWM (HSVPWM) technique is presented to reduce torque ripple of PMSM. The method employs both conventional sequences and advanced bus-clamping switching sequences, which apply an...
This paper presents the application of a humanoid robot as an evaluator of assistive devices; we propose a framework of the evaluation by utilizing identification of the mechanical properties of a humanoid robot. The accurate estimation of joint torque with the identification can enhance the performance to estimate the supporting effect of the devices. We evaluate a passive assistive wear "Smart...
Large flywheel energy storage systems up to megawatt/sub-second range are needed to supply or absorb transient power for pulse loads. Due to its advantages, high power electrically excited synchronous motor is usually preferred in these systems. The Field Oriented Control and Direct Torque Control schemes are two kinds of effective methods used to achieve a stable DC-link voltage. This paper compares...
For the control of robots, like bipedal robots, an accurate system model with the corresponding inertial parameters can enhance the performance of the control algorithms significantly. This paper presents a convenient method for identification of the static inertial parameters with minimal sensor effort. Next to the identification method itself an approach for the calculation of optimal exciting identification...
In this paper two operating modes available for permanent magnet synchronous machines (PMSM) are presented. This study aims to increase the efficiency of the motor-pump system. The PMSM is driven at variable speed and the inverter is controlled by space vector modulation theory. This study allows changing the component that produces magnetic flux (id), while the torque current component of PMSM (i...
In this paper, a new control strategy for Direct Torque Control (DTC) of dual two-level VSI fed 3-phase induction motor drive in an open end winding configuration is presented. The drive can be operated in dual mode; open-end winding or conventional single-sided supply configuration; based on the condition of the motor speed. A block of Optimum Status Detection & Mode Selector (OSD & MS) is...
A sensorless extended Kalman filter (EKF) based direct torque control (DTC) with the use of a constant switching frequency control (CSFC) of induction machine is proposed in this research work. This paper is meant to investigate the dynamic performance for DTC-CSFC and DTC with a hysteresis torque controller by applying different speed step changes from three different low speed operations. The dynamic...
In this paper the design of a linear model predictive controller for a triangular floating platform is presented aiming at the stabilization of its linear and angular velocities as well as its position and orientation. Three rotating jets, located at the corners of the platform, control its motion. With this control configuration, the platform is over-actuated. The prediction, and optimization phase...
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