1,721,123 research outputs found
Torque production capabilities of electrical machines with planar windings
No full textThis paper describes the torque production capabilities of planar magnetics windings and presents an automated procedure for coils conductors’ arrangement. The procedure has been applied on an ironless axial flux slotless permanent magnet machines having planar magnetic stator windings, such as printed circuit board (PCB) coils. The proposed method is driven by optimization techniques whose goal is to find a proper arrangement of PCB traces, which make up stator windings, in order to find some trade-off solutions, optimal respect to the maximization of average torque and the minimization of torque ripple. A time-efficient numerical model has been developed to reduce computational load and thus make the optimization based design attractive
Minimization of proximity losses in electrical machines with tooth-wound coils
Full text linkProximity losses are one of the main drawbacks in electrical machines with high rotational speed and electrical frequency. The reduction of proximity losses is usually pursued by adopting thin wires, which are twisted in the case of parallel connection. Twisting is a very effective solution for reducing proximity losses, but it also worsens the slot filling factor, heat dissipation, and dc resistance. This paper proposes an optimal twisting criterion that allows the minimization of the ac Joule losses due to parasitic circulating currents and reduces the number of twists and the length of the coils. The criterion applies to machines having tooth-wound coils and is validated by finite-element analysis and experimental result
Speed-Sensorless Vector Control of Induction Motors Using EKF
No full textThis paper presents a new method of estimating the
speed, rotor flux components, and parameters of a vector controlled induction motor (IM) using an extended Kalman filter. The estimates are obtained by only measuring the line voltages and currents of the machine. The estimated speed and flux are used for vector control and overall speed control. The online updating of the mathematical-model parameters
guarantees high accuracy in the estimation of speed
and flux components at any load condition, allowing
a correct vector control and an overall speed control.
Computer simulations have been carried out to test
the effectiveness of the proposed estimation algorithm
Real-valued compact genetic algorithms for embedded microcontroller optimization
No full textRecent research on compact genetic algorithms (cGAs) has proposed a number of evolutionary search methods with reduced memory requirements. In cGAs, the evolution of populations is emulated by processing a probability vector with specific update rules. This paper considers the implementation of cGAs in microcontroller-based control platforms. In particular, to overcome some problems related to the binary encoding schemes adopted in most cGAs, this paper also proposes a new variant based on a real-valued solution coding. The presented variant achieves final solutions of the same quality as those found by binary cGAs, with a significantly reduced computational cost. The potential of the proposed approach is assessed by means of an extensive comparative study, which includes numerical results on benchmark functions, simulated and experimental microcontroller design problems
Speed Sensorless Control of Pmsm via Linear Kalman Filtering
No full textThis paper presents a novel PMSM sensorless control scheme based on a linear Kalman filter (LKF) observer. The LKF algorithm estimates the rotor flux components in the stator reference frame by measuring stator currents and voltages, and using a mathematical model based on rotor equations of the motor, and an observation model based on the imaginary power equation. In this way, the LKF algorithm is completely independent on stator resistance, and therefore rotor position estimates are not affected by even strong resistance variations. The proposed observer is linear but time-varying because the rotor speed is treated as a model parameter to be on-line updated. Estimation of rotor speed is performed in two steps: firstly a rough speed estimation is obtained by processing the estimates of rotor position; then a simple speed observer is used to improve the accuracy of speed estimates. The observer output, i.e. the final speed estimate, is fed back to both the speed control loop and LKF algorithm
Dynamic performance comparison of IRFO and SFO-SM controlled drives in field-weakening region using variable-saturation regulators
No full textThis paper proposes to use variable-saturation regulators for Induction Motor (IM) drives operating in field-weakening region, and presents a comparative dynamic-performance analysis between the traditional Indirect Rotor Field Oriented (IRFO) control scheme and a new Stator Flux Oriented - Sliding Mode (SFO-SM) control scheme. The traditional IRFO control scheme has the d-axis current component, torque, rotor flux, and speed loops with four PI-type controllers. The SFO-SM control system is a Direct Torque Control - Space Vector Modulation (DTC-SVM) scheme with closed loops of torque and stator flux without current PI-type controllers. Both control schemes use regulators with variable-saturation in such a way that maximum dc-bus voltage utilization is reached and overcurrent problems are prevented. The experiments are carried out using dSPACE digital controllers and comparative results show that the SFO-SM controlled IM drive and IRFO one are characterized by similar dynamic responses in spite of structural simplicity of the SFO-SM control scheme
Elitist compact genetic algorithms for induction motor self-tuning control
No full textCompact GAs (cGAs) are search methods that, instead of evolving a population of solutions, process a probability vector describing the distribution of a hypothetical population with update rules inspired to the typical selection and recombination operations of a GA. The cGAs well lend themselves to real-time implementations in constrained, low capacity microcontrollers, as they have reduced memory requirement and better distributed computational loads with respect to the standard, population-based GA. This paper investigates the applicability of two cGAs selected from literature to optimize online a PI controller for an induction motor drive. The experimental results are particularly promising, and suggest interesting directions for further researc
The Application of the Wigner-Ville Distribution to Inverter-Fed Induction Motor Fault Detection
No full textThis paper presents the application or the
Wigner-Ville distribution (WVD) to the spectral analysis of the voltage and current systems at the terminals of an
inverter-fed induction motor. The spectral- leakage problem
is studied and the attention is rocused on the effect of
wlndowing. New suitable windows are proposed to provide high-resolution signal characterisation in the time-frequency
space. The results show that the spectral analysis, based on the WVD in conjunction with suitable windows, may be used to determine the occurrence and severity of motor faults
A new IM vector control scheme with two fuzzy logic controllers
No full textThis paper deals with the design of two fuzzy logic controllers (FLCs) for vector-controlled induction motor (IM) drives. Industrial vector drives employ the cascade control scheme, with four PI controllers, to improve dynamic performances. A suitable design of two FLCs permits one to achieve the performances of the cascaded control without using subordinated control loops. FLCs can operate with non-homogeneous inputs therefore they can regulate more than one variable at the same time: the first FLC regulates both speed and stator current generating torque, the second FLC regulates both flux and stator current generating flux. Original criteria based on physical considerations, to determine the input and output gains instead of using the trial and error procedure, are presented. The simplicity of the new FLC-based scheme, together with the given design formulas, reduce the control system development time. The control scheme has been implemented on both a floating point 400MHz Motorola PPC and on a fixed point 20MHz Infineon C167 μcontroller. The computation power in the former case and the use of the fired-rules-hyper-cube (FRHC) approach in the latter one have allowed the μcontrollers to execute the code of two FLCs in a time comparable with that needed by four PI controllers. Details about the μcontroller implementation together with experimental results that prove the effectiveness of the novel IM vector control scheme are give
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