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A novel prediction technique for the direct torque control (DTC) of an induction motor is presented in the paper. The conventional DTC method selects voltage vectors from switching table. The application of these vectors does not satisfy demands for torque increase or decrease at all operating conditions and is not optimal regarding torque ripple. The novel prediction technique calculates in every...
The typical motion of a combustion engine, such as the four-stroke Otto engine, is characterized by a periodic variation of its torque over the rotation angle of the driven shaft. This torque variation leads to the effect of time-varying accelerations and angular velocities. Modeling approaches for combustion engines that can be used for the implementation of control strategies for corresponding engine...
The paper presents a gain-scheduled LQR control system for a nonlinear model of permanent magnet synchronous motor (PMSM). The most popular cascade FOC (Field Oriented Control) structure including a few single-loop PI control systems is replaced with a single multivariable state feedback controller. Due to a nonlinear nature of the PMSM dynamics equations the developed gain-scheduled controller is...
Closed-loop control and modulation of AC drives with offline computed optimized pulse patterns can be achieved by manipulating the time instants of the switching transitions. During torque steps, faults and low-voltage ride through operation, however, the transient response time is often rather slow, due to the absence of an appropriate voltage vector. By inserting additional switching transitions,...
This paper presents a new super-twisting sliding modes direct torque and flux controller (STSM-DTC) for induction motor (IM) drives. The STSM is a second-order (type two) variable-structure control which operates without high-frequency chattering. The proposed STSM scheme is a torque and stator flux magnitude controller implemented in the stator flux reference frame, and it does not employ current...
This paper proposes a novel method for using maximum torque per ampere (MTPA) control for direct torque control (DTC) in the stator flux-linkage synchronous frame (M-T frame). In considering the magnetic-saturation and cross-coupling effects for permanent-magnet synchronous motors (PMSMs), most of the mathematical models in the rotor synchronous (d-q) frame are complex. In the M-T frame, the mathematical...
This paper proposes an encoderless finite state predictive torque control (FS-PTC). In FS-PTC, stator flux and torque are predicted using a finite number of inverter switching states to select an optimal voltage vector to be applied to the motor by actuating a predefined cost function. Up to now, extended Kalman filter (EKF), a promising state observer for encoderless control system, has not been...
A sensorless extended Kalman filter (EKF) based direct torque control (DTC) with a constant switching frequency control (CSFC) of induction motor is proposed in this research work. By replacing the conventional 3-level hysteresis controller with a CSFC, the weakening of the stator flux at low speed is avoided and the flux regulation is improved; consequently the estimated speed at low speed is also...
The paper deals with flux and voltage vector oriented control of a brushless doubly-fed reluctance generator (BDFRG) for grid-connected wind turbines. The BDFRG features the low operation & maintenance costs afforded by using a smaller inverter and the high reliability of brushless structure at potentially competitive performance to its popular slip-ring cousin, the doubly-fed induction generator...
The paper presents a speed sensorless finite state predictive torque control (FS-PTC) for voltage source inverter-fed induction motor drive. The simple model reference adaptive system (MRAS) based flux vector observer enabling speed sensor elimination is also presented. The novelty of the presented system lays in combination of the FS-PTC structure with simple observer for both torque/flux and speed...
This paper deals with a simple voltage model resistance estimator for predictive torque control (PTC) based induction motor (IM) drive. In PTC, flux and torque are predicted to select an optimal voltage vector to be applied to the motor by actuating a predefined cost function. Conventional PTC based control schemes provide poor performance in the very low operating frequencies when the stator flux...
A vector controlled-switched reluctance motor (SRM) drive system is proposed in this paper. As the unipolar excitation current, the sinusoidal current with a DC offset is applied to each circuit in the proposed technique. The excitation current consists of the DC and AC components. These components generate the (virtual) rotor flux and rotating stator field, hence, the vector control system for the...
This paper describes the results of various experimental tests carried out on synchronous reluctance motors with different rotor geometries. The impact of the assistance of Ferrite permanent magnet (PM) inset in the flux-barriers is considered: PM assisted reluctance motors are compared to synchronous reluctance motors, highlighting the main benefits of the former solution. The effect of the rotor...
This paper proposes a pulsating torque control with a voltage suppression period, which is effective in reducing energy consumption and suitable for position-dependent load torque applications. The proposed control method is based on extracting the fundamental periodic component as a sinusoidal variation by applying a simplified Fourier transformation algorithm. The energy consumption can be reduced...
This paper examines the issue of staying within the voltage capacity of a fixed bus voltage inverter during increasing magnetization state (MS) of variable flux permanent magnet synchronous machines (VF-PMSMs). MS manipulation using a fast stator id pulse is shown to induce a large voltage even at low speeds. In order to utilize the power conversion capability and improved efficiency regions of VF...
A performance comparison study for two proposed DC-bus voltage balancing algorithms is carried out, with a three-level NPC based permanent magnet synchronous machine (PMSM) drive for the electric vehicle propulsion application. Both the control algorithms are able to keep the two DC-link capacitor voltage variation within a tolerance level with wider range of speed and torque variation of the load...
This paper proposes a hexagon voltage manipulating control (HVMC) method for ac motor drives operating at voltage limits. The command output voltage can be simply determined by the torque command and the hexagon voltage boundary in the absence of PI control gains, additional MTPV tracking controllers, and observers for closed-loop control. These attributes reduce the time and effort required for the...
This paper proposes a flux vector-based discrete-time direct torque control (DTC) scheme for salient-pole permanent-magnet synchronous generators (PMSGs) used in the variable-speed, direct-drive wind energy conversion systems (WECSs). The discrete-time control law is derived from the perspective of flux space vectors and load angle with the torque and stator flux information only. The saliency of...
Based on the mathematic model of PMSM, two methods of flux-weakening control based on Single Current Regulator are studied in this paper, which are Variable Q-axis Voltage Control (VQVC) and Voltage Angle Control (VAC). By comparing their control theory, it is shown obviously that both two control methods have good robustness, while the means of getting d-axis voltage and q-axis voltage of the two...
This paper describes a novel method for the identification of time-varying ankle joint dynamic stiffness during large passive movements. The method estimates a linear parameter varying parallel-cascade (LPV-PC) model of joint stiffness consisting of two pathways: (a) an LPV impulse response function (IRF) for intrinsic mechanics and (b) an LPV Hammerstein cascade with time-varying static nonlinearity...
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