Search results for "ILTER"
showing 10 items of 1040 documents
Descriptor-type Robust Kalman Filter and Neural Adaptive Speed Estimation Scheme for Sensorless Control of Induction Motor Drive Systems
2012
Abstract This paper deals with robust estimation of speed and rotor flux for sensorless control of motion control systems which use induction motors as actuators. Due to the observability lack of five and six order Extended Kalman Filters, speed is here estimated by means of a Total Least Square algorithm with Neural Adaptive mechanism. This allows the use of a fourth-order Kalman Filter for estimating rotor flux and to filter stator currents. To cope with motor-load parameter variations, a descriptor-type robust Kalman Filter is designed taking explicitly into account these variations. The descriptor-type structure allows direct translation of parameter variations into variations of the co…
Hardware implementation of a robust adaptive filter: Two approaches based in High-Level Synthesis design tools
2009
Abstract Adaptive filters are used in a wide range of applications. Impulsive noise affects the proper operation of the filter and the adaptation process. This noise is one of the most damaging types of signal distortion, not always considered when implementing algorithms. Field Programmable Gate Array (FPGA) are widely used for applications where timing requirements are strict. Nowadays, two main design processes can be followed, namely, Hardware Description Language (HDL) and a High Level Synthesis (HLS) design tool for embedded system design. This paper describes the FPGA implementation of an adaptive filter robust to impulsive noise using two approaches based in HLS and the implementati…
Phase Margin Degradation of a Peak Current Controlled Converter at Reduced Duty Cycle
2010
An inner current loop is frequently used in many switching power supplies to achieve higher stability and a good current sharing. Nevertheless, some problems derived from its practical implementation can be encountered. One problem is related to the need of filtering of the sensed current and was discovered by the authors in the implementation of a 500 W converter, when peak current control was applied by sensing the switch current. This paper will demonstrate mathematically that an RC filter not only filters out the noise but also can cause a degradation of the phase margin, especially, if the needed duty cycle is close to zero. The main reason for it is the severe distortion of the curren…
A structured filter for Markovian switching systems
2014
In this work, a new methodology for the structuring of multiple model estimation schemas is developed. The proposed filter is applied to the estimation and detection of active mode in dynamic systems. The discrete-time Markovian switching systems represented by several linear models, associated with a particular operating mode, are studied. Therefore, the main idea of this work is the subdivision of the models set to some subsets in order to improve the detection and estimation performances. Each subset is associated with sub-estimators based on models of the subset. In order to compute the global estimate and subset probabilities, a global estimator is proposed. Theoretical developments ba…
Bearing fault detection for drivetrains using adaptive filters based wavelet transform
2017
Predicting a localized defect on a rolling bearing during the degradation process before a complete failure is crucial to prevent system failures, unscheduled downtimes and substantial loss of productivity. During this process, impulses associated with the fault are weak, nonstationary or time-frequency varying, and contaminated by noises, which render the problem of extracting these impulses very difficult. This work investigates the effectiveness of common signal processing techniques on predicting incipient faults, e.g. Fast Fourier transform, Short-Time Fourier transform, Wavelet transform. It was found that an adaptive filter is required to enhance and reconstruct the signals during th…
Robustness Analysis of an Extended Kalman Filter for Sensorless Control of Induction Motors
2010
This paper deals with robustness analysis of Extended Kalman Filters (EKFs) for sensorless motion control of induction motors. Analysis is carried out by means of simulation experiments considering a conventional EKF, in which system and measurement noise covariance matrices are constant, and an adaptive EKF in which the system noise covariance matrix is updated on-line using a PID-type algorithm driven by the stator current estimation errors.
A Memetic Differential Evolution in Filter Design for Defect Detection in Paper Production
2007
This article proposes a Memetic Differential Evolution (MDE) for designing digital filters which aim at detecting defects of the paper produced during an industrial process. The MDE is an adaptive evolutionary algorithm which combines the powerful explorative features of Differential Evolution (DE) with the exploitative features of two local searchers. The local searchers are adaptively activated by means of a novel control parameter which measures fitness diversity within the population. Numerical results show that the DE framework is efficient for the class of problems under study and employment of exploitative local searchers is helpful in supporting the DE explorative mechanism in avoid…
Velocity sensorless control of uncertain load using RKF tuned with an evolutionary algorithm and mu-analysis
2010
Abstract In case of a velocity control scheme for a load directly driven by an actuator, large variations of its parameters are problematic due to possible instability and large variations of the final performances. This performances are then decreasing if a sensorless control is implemented due to cost, reliability or application constraints. This paper proposes solutions to quickly and accurately tune an observer with a lower computer time consumption and lower conception time. A previous calculated state feedback is used as base for a Kalman filter with special noise matrices. An evolutionary algorithm optimizes the observers degrees of freedom all over the variations. The mu-analysis th…
Exploring FPGA‐Based Lock‐In Techniques for Brain Monitoring Applications
2017
Functional near‐infrared spectroscopy (fNIRS) systems for e‐health applications usually suffer from poor signal detection, mainly due to a low end‐to‐end signal‐to‐noise ratio of the electronics chain. Lock‐in amplifiers (LIA) historically represent a powerful technique helping to improve performance in such circumstances. In this work a digital LIA system, based on a Zynq® field programmable gate array (FPGA) has been designed and implemented, in an attempt to explore if this technique might improve fNIRS system performance. More broadly, FPGA‐based solution flexibility has been investigated, with particular emphasis applied to digital filter parameters, needed in the digital LIA, and its …
A Technique for Power Supply Harmonic Impedance Estimation Using a Controlled Voltage Disturbance
2002
A method for power system impedance estimation is presented. The method employs a power converter to inject a voltage transient onto the supply system. As the technique employs controlled power electronic devices it may be used as a stand alone piece of a portable measurement equipment, or it may be embedded into the functions of an active shunt filter for improved harmonic control. The impedance is estimated through correlation of the measured voltage and current transients. Simulations and experimental results demonstrate the measurement technique is highly accurate and effective.