Digital Signal Processor Board Research Articles

Interfacing Renewable Energy Sources to the Utility Grid Using a Three-Level Inverter

This paper presents a novel approach for the connection of renewable energy sources to the utility grid. Due to the increasing power capability of the available generation systems, a three-level three-phase neutral-point-clamped voltage-source inverter is selected as the heart of the interfacing system. A multivariable control law is used for the regulator because of the intrinsic multivariable structure of the system. A current source (playing the role of a generic renewable energy source) is connected to the grid using a three-level inverter in order to verify the good performance of the proposed approach. Large- and small-signal d-q state-space averaged models of the system are obtained and used to calculate the multivariable controller based on the linear quadratic regulator technique. This controller simultaneously regulates the dc-link voltage (to operate at the maximum power point of the renewable energy source), the mains power factor (the power is delivered to the grid at unity power factor), and the dc-link neutral-point voltage balance. With the model and regulator presented, a specific switching strategy to control the dc-link neutral-point voltage is not required. The proposed controller can be used for any application, since its nature makes possible the control of any system variable. The good performance of the presented interfacing solution in both steady-state and transient operation is verified through simulation and experimentation using a 1-kW neutral-point-clamped voltage-source-inverter prototype, where a PC-embedded digital signal processor board is used for the controller implementation

Ethernet Based Distributed Data Acquisition System for a Small Animal PET

We report on the design of a small animal PET scanner being developed at our institutes. The existing setup is the first version of the miniPET machine consisting of four detector modules. Each detector module consists of an 8times8 LSO scintillator crystal block, a position sensitive photomultiplier, a digitizer including a digital signal processing board and an Ethernet interface board. There is no hardware coincidence detection implemented in the system and coincidence is determined based on a time stamp attached to every event by a digital CFD algorithm. The algorithm is implemented in the digital signal processing board and generates a time stamp with a coincidence resolution of less than 2 ns. The data acquisition system is based on Ethernet network and is highly scalable in size and performance

Vibration control of piezoelectric smart structures based on system identification technique: Numerical simulation and experimental study

The aim of this study is to investigate the efficiency of a system identification technique known as observer/Kalman filter identification (OKID) technique in the numerical simulation and experimental study of active vibration control of piezoelectric smart structures. Based on the structure responses determined by finite element method, an explicit state space model of the equivalent linear system is developed by employing OKID approach. The linear quadratic Gaussian (LQG) algorithm is employed for controller design. The control law is then incorporated into the ANSYS finite element model to perform closed loop simulations. Therefore, the control law performance can be evaluated in the context of a finite element environment. Furthermore, a complete active vibration control system comprising the cantilever plate, the piezoelectric actuators, the accelerometers and the digital signal processor (DSP) board is set up to conduct the experimental investigation. A state space model characterizing the dynamics of the physical system is developed from experimental results using OKID approach for the purpose of control law design. The controller is then implemented by using a floating point TMS320VC33 DSP. Numerical examples by employing the proposed numerical simulation method, together with the experimental results obtained by using the active vibration control system, have demonstrated the validity and efficiency of OKID method in application of active vibration control of piezoelectric smart structures.

A Fast Continuous Magnetic Field Measurement System Based on Digital Signal Processors

In order to study dynamic effects in accelerator magnets, such as the decay of the magnetic field during the dwell at injection and the rapid so-called "snapback" during the first few seconds of the resumption of the energy ramp, a fast continuous harmonics measurement system was required. A new magnetic field measurement system, based on the use of digital signal processors (DSP) and Analog to Digital (A/D) converters, was developed and prototyped at Fermilab. This system uses Pentek 6102 16 bit A/D converters and the Pentek 4288 DSP board with the SHARC ADSP-2106 family digital signal processor. It was designed to acquire multiple channels of data with a wide dynamic range of input signals, which are typically generated by a rotating coil probe. Data acquisition is performed under a RTOS, whereas processing and visualization are performed under a host computer. Firmware code was developed for the DSP to perform fast continuous readout of the A/D FIFO memory and integration over specified intervals, synchronized to the probe's rotation in the magnetic field. C, C++ and Java code was written to control the data acquisition devices and to process a continuous stream of data. The paper summarizes the characteristics of the system and presents the results of initial tests and measurements

Development of an Open Architecture CNC System for a Wire-EDM Machine

This paper presents an open architecture CNC system for wire-EDM. The main part of the system is integrated combination of a real-time operating system running on a digital signal processor (DSP) board and a Window-based environment running on a PC. The hardware system consists of a master PC, DSP-based control card, an input-output interface card and a network card. The software system consists of operation, machine logic control, motion, machining process control, interpreter, man machine interface and communication. The proposed CNC system is featured with open architecture human machine interface, flexibility, modularity and Internet connectivity. The original CNC system has been superseded in a commercial wire-EDM machine by the developed CNC system. Experimental results verified the usefulness of the developed CNC system in manufacturing automation.

Correction of Saturated Current Transformers Secondary Current Using ANNs

Current transformers (CTs) provide instrument-level current signals to meters and protective relays. Protective relays' accuracy and performance are directly related to steady-state and transient performance of CTs. CT saturation could lead to protective relay maloperation or even prevent tripping. This paper proposes the use of an artificial neural networks scheme to correct CT secondary waveform distortions. The proposed module uses samples of current signals to achieve the inverse transfer function of CT. Simulation studies are preformed and the influence of changing different parameters is studied. Performance studies results show that the proposed algorithm is accurate and reliable. The proposed algorithm has also been implemented and tested on a digital signal processor board. Details of the implementation and experimental studies are provided in this paper.

EXPERIMENTAL STUDIES ON A PROTO-TYPE POWER SYSTEM USING AN ADAPTIVE PSS

Experimental studies with an adaptive power system stabilizer (APSS) using radial basis function network as a system model identifier (RBF-Identifier) and a linear feedback pole-shift (PS) controller are presented in this paper. The physical model of the power system consists of a 3kV A, 220V synchronous micro-alternator and a transmission line that simulates the performance of a 500kV double-circuit transmission line. A commcrical programmable logic controller provides the AVR function and the APSS is implemented on a digital signal processing (DSP) board. The weights of the RBF-Identifier are updated on-line and the network is linearized at every sampling interval to obtain the ARMA model parameters of the system. The PS controller uses the on-line updated ARMA parameters to obtain the optimal control signal at the given instant. The tests demonstrate that the proposed APSS is effective in damping oscillations and improving power system stability.

Development of an Automated Umbilical Cord Blood Collection System

In this paper, the development of an automated umbilical cord blood (UCB) collection system is presented. The overall control system is comprehensive, comprising of various selected control and instrumentation components, integrated within a configuration of hardware architecture centered around a dSPACE DS1002 Digital Signal Processing (DSP) board. The hardware architecture, software development platform, user interface, and all constituent control components will be elaborated on in the paper.

An artificial neural network for online tuning of genetic algorithm-based PI controller for interior permanent magnet synchronous motor drive

An artificial neural network (ANN) for online tuning of a genetic algorithm based PI controller for interior permanent magnet synchronous motor (IPMSM) drive is presented in this paper. The proposed controller is developed for accurate speed control of the IPMSM drive under system disturbances. In this work, initially different operating conditions are obtained based on motor dynamics incorporating various uncertainties. At each operating condition a genetic algorithm (GA) is used to optimize proportional-integral (PI) controller parameters in a closed loop vector control scheme. In the optimization procedure a performance index is developed to reflect the minimum speed deviation, minimum settling time and zero steady-state error. A radial basis function network (RBFN) is utilized for online tuning of the PI controller parameters to ensure optimum drive performance under different disturbances. The proposed controller is successfully implemented in real-time using a digital signal processor board DS1102 for a laboratory 1 hp IPMSM. The efficacy of the proposed controller is verified by simulation as well as experimental results at different dynamic operating conditions. The proposed approach is found to be a robust controller for application in the IPMSM drive

An ANN-Based High Impedance Fault Detection Scheme: Design and Implementation

This paper presents a new approach to detection of high impedance faults in distribution systems using artificial neural networks. The proposed neural network, was trained by data from simulation of a distribution system under different faults conditions, and tested by data with different system conditions. The proposed neural network has been implemented on a digital signal processor board and its behavior is investigated on a computer power system model. Details of the design procedure, implementation and the results of performance studies with the proposed relay are given in this paper. Performance studies results show that the proposed algorithm performs very well in detecting a high impedance fault with nonlinear arcing resistance. It is clearly shown that with this integrated approach, the accuracy in fault detection is significantly improved compared to other techniques based on conventional algorithms.

Sensor design and signal processing for an advanced sonar ring

A conventional sonar ring measures the range to objects based on the first echo and is widely used in indoor mobile robots. In contrast, advanced sonar sensing can produce accurate range and bearing (incidence angle) measurements to multiple targets using multiple receivers and multiple echoes per each receiver at the expense of intensive computation. This paper presents an advanced sonar ring that employs a low receiver sample rate to achieve processing of 48 receiver channels at near real time repetition rates of 11.5 Hz. The sonar ring sensing covers 360 degrees around the robot for specular targets for ranges up to six metres, with simultaneously firing of all its 24 transmitters. Digital Signal Processing (DSP) techniques and interference rejection ideas are applied in this sensor to produce a fast and accurate sonar ring. Seven custom designed DSP boards process the receivers sampled at 250 kHz to maximize the speed of processing and to limit memory requirements. This paper presents the new sensor design, the hardware structure, the software architecture, and signal processing of the advanced sonar ring. Repeatability and accuracy of the measurements are tested to characterize the proposed sensor. Due to the low sample rate of 250 kHz, a problem called cycle hopping can occur. The paper presents a solution to cycle hopping and a new transmit coding based on pulse duration to differentiate neighbouring transmitters in the ring. Experimental data show the effectiveness of the designed sensor in indoor environments.

Continuous monitoring guided wave encoded sensor for oil rig flooded member detection

Structural flooded member detection of offshore oil platforms involves the detection of seawater in their normally hollow steel crossbeam members. NDT methods such as ultrasound have been used to inspect for the presence of water in these applications, often in conjunction with remote operating vehicles. Alternatively, a guided wave sensor system is now being developed which can be permanently attached to a sub-sea installation and that can be powered by the action of the seawater. Upon activation, the transducer is able to transmit encoded information to monitoring systems at deck level. Present work has focused on the assessment of guided waves and their attenuation not only due to steel joints and distance but also due to leaky waves coupled into surrounded water. Low-frequency excitation exhibits lower attenuation depending on the selected mode, however this can also be exposed to acoustic interference leading to a poor SNR. A compromise between these factors has been considered in this application for the successful transmission and reception of encoded information. Low-power narrow-bandwidth chirp signals were employed with 21 kHz PZT transducers to excite axisymmetric modes in tubes. Experiments have been carried out using excitations of 0.5 V and 5 V respectively for a water-loaded steel k-joints scale model and a cylindrical bridge steel structure with several k-joints. Important results have been attained, moreover in order to reduce acoustic noise a real-time digital signal processing board has been used to perform digital filtering and signal identification.

Parallel hardware implementation of RADAR electronics equipment for a LASER inspection system

An amplitude modulated laser radar has been developed by the Italian Agency for New Technologies, Energy and the Environment for periodic in-vessel inspection in large fusion machines (International Thermonuclear Experimental Reactor). The system is able to obtain a complete three-dimensional mapping of the in-vessel surface. A first digital signal processing system was developed to modulate the laser beam and to detect both the amplitude of the backscattered light and the phase difference between it and the modulation signal. This system is based on commercial digital receiver and parallel digital signal processing boards on a VME bus. It reaches a speed of 100 K measures/s, showing good accuracy and stability. Starting from this, a further development has been done to increase the speed up to 2.328 M measures/s. Reaching the submicrosecond speed was necessary to implement the mathematical algorithm in a highly parallel hardware architecture using a field programmable gate array (FPGA). Based on the good results of the previously developed system, it was decided to maintain the same acquisition front-end though using the last release of analog-to-digital converters, to increase the operating frequency from 80 up to 200 MHz. The software algorithm previously used was completely redesigned and optimized to be used in the FPGA hardware architecture

A SIMPLE FUZZY LOGIC SPEED CONTROLLER FOR A DC MOTOR FED BY SEPIC CONVERTER

This paper presents a closed loop speed controi of a separately excited DC motor. A cascade combination of a diode bridge rectifier and single-ended primary inductor converter (SEPIC) is used to feed the DC motor from an AC supply. This circuit combination offers both step-up and step-down characteristics of the motor terminal voltage as well as an approximately sinusoidal supply current with an improved power factor. A fuzzy logic speed controller is used to overcome any system nonlinearity and parameter changes. Also. a wide range of both speed and load changes with satisfactory response is obtained. Two fuzzy membership functions are used reflecting few and simple control rules. Moreover. a genetic algorithm (GA) is used to optimally tune the fuzzy controller parameters. Simulation results of the system are obtained by solving the differential equations in different modes of operation. The system is laboratory implemented and the controller is investigated using a digital signal processing board (DSPI 104). The experimental and simulation results are verified and a correlation between both has been found. The results confirm the relevance of the proposed configuration a- a useful rectifier that achieves sinusoidal supply current, high power factor and motor speed regulator.

Real-Time Testing of a WPT-Based Protection Algorithm for Three-Phase Power Transformers

This paper presents real-time implementation and testing of a wavelet-packet-transform-based algorithm for power transformer protection. The proposed algorithm is implemented using a DS1102 digital signal processor board and tested on two different three-phase power transformers. Different magnetizing inrush, normal (through-fault) and internal fault currents are investigated for different loading conditions. The results show a complete independence from both the transformer parameters and current transformer saturation. In addition, the proposed algorithm has reduced computational burden, high speed, high accuracy, small required memory, and high reliability. In all cases of the investigated internal faults, the proposed algorithm is capable of identifying the fault and generating a trip signal in less than a quarter cycle based on a 60-Hz system.

DSP Implementation of the Multiple Reference Frames Theory for the Diagnosis of Stator Faults in a DTC Induction Motor Drive

This paper deals with the use of a new diagnostic technique based on the multiple reference frames theory for the diagnosis of stator winding faults in a direct-torque-controlled (DTC) induction motor drive. The theoretical aspects underlying the use of this diagnostic technique are presented but a major emphasis is given to the integration of the diagnostic system into the digital-signal-processor (DSP) board containing the control algorithm. Taking advantage of the sensors already built in the drive for control purposes, it is possible to implement this diagnostic system at no additional cost, thus giving a surplus value to the drive itself. Experimental results show the effectiveness of the proposed technique to diagnose stator faults and demonstrate the possibility of its integration in the DSP board.

Real time monitoring and diagnosis system development in turning through measuring a roundness error based on three-point method

A real time monitoring and diagnosis system to measure spindle center displacement (roundness error) during turning operation is introduced in this paper. The system was developed based on the three-point method. The error generated during cutting process was monitored and diagnosed by using a system equipped with a designed DSP (Digital Signal Processor) board and FFT (Fast Fourier Transform) algorithm. The system could estimate cutting force and predict other cutting characteristics such as chattering and tool wear. Using the spindle center fluctuation, i.e. a roundness error movement from the center, the relationship between the cutting force and the roundness error could also be investigated. The roundness error that eliminated geometric shape error and eccentric error from the measured signals in the frequency domain proved to be a dominating factor in determining cutting characteristics.

A low-cost, high-performance, digital signal processor-based lock-in amplifier capable of measuring multiple frequency sweeps simultaneously

A high-performance digital lock-in amplifier implemented in a low-cost digital signal processor (DSP) board is described. This lock in is capable of measuring simultaneously multiple frequencies that change in time as frequency sweeps (chirps). The used 32-bit DSP has enough computing power to generate N=3 simultaneous reference signals and accurately measure the N=3 responses, operating as three lock ins connected in parallel to a linear system. The lock in stores the measured values in memory until they are downloaded to the a personal computer (PC). The lock in works in stand-alone mode and can be programmed and configured through the PC serial port. Downsampling and multiple filter stages were used in order to obtain a sharp roll off and a long time constant in the filters. This makes measurements possible in presence of high-noise levels. Before each measurement, the lock in performs an autocalibration that measures the frequency response of analog output and input circuitry in order to compensate for the departure from ideal operation. Improvements from previous lock-in implementations allow measuring the frequency response of a system in a short time. Furthermore, the proposed implementation can measure how the frequency response changes with time, a characteristic that is very important in our biotechnological application. The number of simultaneous components that the lock in can generate and measure can be extended, without reprogramming, by only using other DSPs of the same family that are code compatible and work at higher clock frequencies.

Real-Time Performance Evaluation of a Genetic-Algorithm-Based Fuzzy Logic Controller for IPM Motor Drives

This work presents a novel speed control scheme using a genetic-based fuzzy logic controller (GFLC) for an interior permanent-magnet synchronous motor (IPMSM) drive. The proposed GFLC is developed to have less computational burden, which makes it suitable for real-time implementation. The parameters for the GFLC are tuned by genetic algorithm (GA). The complete drive incorporating the GFLC is successfully implemented in real-time using a digital signal processor board DS 1102 for a laboratory 1-hp interior permanent magnet motor. The efficacy of the proposed GFLC-based IPMSM drive is verified by simulation as well as experimental results at various operating conditions. A performance comparison with a conventional proportional-integral controller is also provided to show the superiority of the proposed controller. The proposed GFLC is found to be robust for high-performance industrial drive applications.

Hybrid fuzzy controller for speed control of switched reluctance motor drives

A hybrid fuzzy controller for speed control of switched reluctance motor (SRM) drives is presented in this paper. The developed hybrid fuzzy control law consists of a proportional integral (PI) controller at steady state, a PI type fuzzy logic controller (FLC) at transient state and a simple logic controller between the steady and transient states to achieve the desired performance at various operating conditions under soft chopping operation. The importance of the hybrid fuzzy controller is highlighted by comparing the performance of various control approaches, including PI control, PI type fuzzy logic control and PD type fuzzy control for speed control of SRM motor drives. The complete control algorithm is demonstrated by intensive experimental results. It is shown that the presented hybrid controller for SRM drive has fast tracking capability, less steady state error and is robust to load disturbance. The complete speed control scheme of the SRM drive incorporating the hybrid control is experimentally implemented and validated using a high speed digital signal processor board TMS320F2812 for a prototype 1.2 kW SRM.