PCI eXtensions For Instrumentation Research Articles

Design of the data acquisition system of acceleration grid power supply for CFETR N-NBI prototype

The Acceleration Grid Power Supply (AGPS) of the China Fusion Engineering Test Reactor (CFETR) negative-ion-based neutral beam injector (N-NBI) prototype is a high-voltage power supply rated at -200 kV/25 A. The output voltage measurement and state detection of AGPS are required to safely operate for the N-NBI system. Hence, a high-performance data acquisition system is essential. The performance requirements of the data acquisition system becomes remarkable when the output voltage increases and electromagnetic interference enhance. This paper proposes an effective data acquisition method based on field programmable gate array (FPGA) technology and PCI extensions for instrumentation (PXI) series hardware used in the existing control system. Compared with traditional voltage-to-frequency (VF) conversion methods, the frequency output by the proposed method can maintain a consistently high standard when a lower reference output voltage is required. The principle test and high voltage test on the pulse step modulation (PSM) power supply of the J-TEXT Tokamak indicate that the delay of the data acquisition system is no more than 20 μs, which fulfills the requirements.

Digital Compensation of a Resistive Voltage Divider for Power Measurement

The paper presents a method for digital compensation of the ratio and phase angle errors of a resistive voltage divider. The system consists of a separate electrical circuit of a resistive divider, and a digital compensation system based on National Instruments (NI) PCI eXtension for Instrumentation (PXI) PXI-5922 digital acquisition cards (DAQ). A novel approach to the real-time compensation is presented, using digital signal processing. The algorithm is based on Wiener filtering and finite-impulse-response (FIR) filters. The proposed digital compensation, using FIR digital filtration and NI PXI DAQs, gives maximum magnitude error below 400 ppm and the phase angle error below 4500 μrad, in the frequency band 50 Hz–100 kHz. The algorithm allows the fine-tuning of the compensation to adjust to the possible change in the original transfer function due to the aging of the components.

A Wireless Instrumentation Control System Based on Low-Cost Single Board Computer Gateways

Nowadays, most of the automatized measurement processes are carried out by VISA (Virtual Instrument Software Architecture) compatible instruments, that execute the instructions provided by a host computer connected through wired standard buses, as USB (Universal Serial Bus), GPIB (General-Purpose Instrumentation Bus), PXI (PCI eXtensions for Instrumentation) or Ethernet. To overcome the intrinsic limitations associated to these wired systems, this work presents an instrumentation control system based on the IEEE 802.11 wireless communications standard. Intended for instruments having a USB control port, this port is connected to a gateway based on a compact Raspberry Single Board Computer (SBC) and thus the instrument can be connected to the host computer via Wireless Fidelity (WiFi), easily allowing the deployment of an ad-hoc instruments communication network in the working area or its connection to a previously deployed general purpose WiFi network. Developed under Python, the operation commands, wireless link protocol, and USB connection allow two modes of operation to provide system flexibility: a live mode, where commands are sent individually from the host computer to the selected instrument; and a standalone mode, where a full measurement process can be entirely downloaded in the gateway to be autonomously executed on the instrumentation. The system performance in both operation modes, distance of operation, time latencies, and operating lifetime in battery operation have been characterized.

Real-Time Controller Design Test Bench for High-Voltage Direct Current Modular Multilevel Converters

Modular multilevel converters (MMCs), with their inherent features and advantages over other conventional converters, have gained popularity and remain an ongoing topic of research. Many scholars have solved issues related to the operation, control, protection, and reliability of MMCs using simulation software and small hardware prototypes. We propose a novel approach for an MMC controller design with real-time systems. By utilizing a key benefit of LabVIEW Multisim co-simulation, an MMC control algorithm that can be deployed on a field-programmable gate array (FPGA) was developed in LabVIEW. The complete circuit was designed in Multisim, and a co-simulation was performed to drive an MMC model. The benefit of this topology is that control algorithms can be designed in a LabVIEW FPGA and tested with the Multisim co-simulation circuit to obtain simulation results. Once the controller works and provides satisfactory results, the same algorithm can be deployed in any NI (National Instruments) FPGA-based controller, like a compact remote input/output (RIO), to control real-time MMCs designed in an NI PCI eXtensions for Instrumentation (PXI) system. This method saves time and provides flexibility for effectively designing control algorithms and implementing them in an FPGA for real-time model implementation.

An Automated Testing Method for PXI Chassis Software Driver

PCI extensions for instrumentation (PXI) chassis is a multi-vendor interoperable device. It can interconnect with many chassis, module and computers. To make sure a device driver is able to function in a specific configuration, it must go through a series of tests. The complexity of PXI software testing has increased when it needs to cover multiple configurations for a single driver. Majority of the automated test systems will execute tests without having the mechanism to verify the test environment. To improve the PXI chassis driver test duration, the current trend of automated software testing only executes a single test configuration. Thus, an automated test software with the capability to execute multi-test configuration is required. In order to develop this tool, a server-client concept is adopted. The advantage of server-client is to centralize the testing when multiple tests are performed. The software tool client will start once it is booted into the operating system; the test system will connect to server and wait for further action from server. When server detects incoming client connection, it will automatically verify and fix the testing environment; if the client fulfills the test suite requirement it will start to execute the test system. All client test summary results will be updated to the server. The results show an average of 17.1% test duration reduction on the planned test configuration when the automated software tool is applied on testing. Besides, the results indicate higher controller hardware performance can reduce the test duration.

Development of a Time-of-Flight Electronics System for Neutron Beam Profiling at CSNS-WNS

A 256-channel time-of-flight (TOF) electronics system has been developed for a beam line facility called "Back-n WNS" in China Spallation Neutron Source (CSNS). This paper shows the structure and performance of electronics system and the test results in CSNS. A 256-channel photomultiplier tube (PMT) is chosen as the detector in this system. In order to acquire the time information from the PMT, an electronics system has been designed. The electronics system mainly includes one front-end board (FEB), four time-to-digital converter (TDC) boards and one clock distribution module (CDM). There are 256 channels on FEB and 64 channels on each TDC board. The FEB is connected to the PMT with high-density connectors and the TDC boards are connected to the FEB through 2m cables. The TDC boards are 6U size so that they can be PCI extensions for Instrumentation (PXI) cards. Data from TDC boards can be transferred to the PXI control card through the backboard. In order to make four TDC boards work synchronously, a CDM outputs four clock signals to TDC boards which are distributed from one clock source. The TDC boards achieve a timing resolution of 3.5ns by test with a signal generator. The TOF measurement system has been used in CSNS.

Design of the control system of acceleration grid power supply for CFETR N-NBI prototype

In order to realize the 200 keV negative-ion-based neutral beam injector (N-NBI) prototype of China Fusion Engineering Test Reactor, an acceleration grid power supply (AGPS) is under development. Adopting a single stage inverter type topology, the AGPS is rated at 200 kV/25A for 3600 s. Here, the paper presents a distributed control system based on PCI extensions for instrumentation (PXI) and field programmable gate array (FPGA) technology, which can fulfill the high requirements in terms of the control strategy, malfunction protection, integration with the upper control system and real-time monitoring, highlighting the operation sequence both in normal and abnormal scenarios. In addition, a 10 kV/6A AGPS prototype has been realized to verify the control system. The distributed control system can respond to the interlock signal from the upper controller within 2 μs while disabling the inverter within 20 μs in case of an abnormal current or voltage output status.

A New Method of Recording Generator Dynamics and Its Application to the Derivation of Synchronous Machine Parameters for Power System Stability Studies

The proposed algorithm is based on the discrete Fourier transform (DFT) and a software-based synchronous sampling technique that is locked to the power system frequency using reconfigurable field-programmable gate arrays (FPGAs). The main purposes of this paper are to provide a new method of recording the high-resolution rotor angle of a synchronous machine and a practical method for deriving more accurate d-q- axis synchronous machine parameters. An FPGA is used in realizing the rotor-angle transducer and it simultaneously detects the frequency of the generator terminal voltage. The DFT algorithm is combined with an interpolation technique that downsamples the high-frequency sampled data using the measured power system frequency. This paper also describes a practical method for determining synchronous machine model parameters. The proposed algorithm for recording the generator dynamics was implemented in terms of Labview, Real-Time PCI eXtensions for Instrumentation (PXI) target, and the FPGA, and was applied to generator testing of a 1205-MVA thermal power unit. Its synchronous machine parameters were also derived using the recorded rotor angle.

Development of data acquisition and over-current protection systems for a suppressor-grid current with a neutral-beam ion source

Neutral beam injection is one of the effective auxiliary heating methods in magnetic-confinement-fusion experiments. In order to acquire the suppressor-grid current signal and avoid the grid being damaged by overheating, a data acquisition and over-current protection system based on the PXI (PCI eXtensions for Instrumentation) platform has been developed. The system consists of a current sensor, data acquisition module and over-current protection module. In the data acquisition module, the acquired data of one shot will be transferred in isolation and saved in a data-storage server in a txt file. It can also be recalled using NBWave for future analysis. The over-current protection module contains two modes: remote and local. This gives it the function of setting a threshold voltage remotely and locally, and the forbidden time of over-current protection also can be set by a host PC in remote mode. Experimental results demonstrate that the data acquisition and over-current protection system has the advantages of setting forbidden time and isolation transmission.

A Software Defined Radio based UHF Digital Ground Receiver System for Flying Object using LabVIEW

This study demonstrates the design and implementation of a software defined radio based digital ground receiver system using LabVIEW. In flight testing centre, command transmission system is used to transmit specific commands to execute some operation inside the flight vehicle. One ground receiver system is needed to monitor the transmitted command and monitor the presence of the command in air. The newly implemented ground receiver system consists of FPGA, RTOS and general processing unit. The analog to digital conversion and RF down conversions are carried out in high speed PCI extension for instrumentation express cards. The communication algorithms, digital down conversion are implemented in FPGAs. The communication system uses digital demodulation and decoding scheme and realised by NI PXI-7966R with Xilinx Virtex 5, SXT, FPGA. The performance of the receiver system has been analysed by linearity measurement of pre-amplifier Gain, Noise figure, frequency, power and also measurement of sensitivity. The results show successful implementation of the ground receiver system.

The transient electric field measurement system for EAST device

The electromagnetic environment around the Experimental Advanced Superconducting Tokamak (EAST) device is very complex during plasma discharge experiment. In order to fully monitor the changes of electric field around the EAST device during plasma discharge, a transient electric field measurement system based on PCI eXtensions for Instrumentation (PXI) platform has been designed. A digitizer is used for high-speed data acquisition of raw signals from electric field sensors, and a Field Programmable Gate Array (FPGA) module is used for realizing an on-the-fly fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) algorithm including a beforehand identified antenna factor (AF) to achieve finally a calibrated and filtered electric field measurement, then these signals can be displayed and easily analyzed. The raw signals from electric field sensors are transferred through optical fiber by optical isolation to reduce electromagnetic interference (EMI). The high speed data streaming technology is used for data storage. A prototype of this system has been realized to measure the transient electric field strength, with the real-time processing and continuous acquisition ability of one channel of 14-bit resolution and up to 50MHz sampling rate, and 6 KHz FFT frequency resolution.

Standardization of automated industrial test equipment for mass production of control systems

Power converters and their controls electronics are key elements for the operation of the CERN accelerator complex, having a direct impact on its availability. They must be designed to achieve a high Mean Time Between Failure (MTBF) and hardware reliability must be ensured by board level testing before hardware is assembled and installed. In this framework, the National Instrument PCI extension for Instrumentation (PXI) was chosen as standard platform for the development of testers. This paper reports on the design strategy and approach used focusing on the tester hardware, firmware and software development.

The Timing System of the Neutral Beam Injector on EAST

In order to synchronize the elements of the EAST Neutral Beam Injector (NBI) spatially located in several places, a distributed Timing System (TS) is developed in this paper. The timing system provides a clock reference for synchronization and an interlock protection of the EAST NBI system. It sends timing signals to field devices, controls the pulse widths of the timing sequences, and provides a sampling clock for the Data Acquisition System (DAS). The timing system also generates analog waveforms to control power supplies and gas supplies according to the operator's configuration. The timing system is developed on a PXI (PCI eXtensions for Instrumentation) platform consisting of a LabVIEW workstation and a timing control terminal. The timing control terminal consists of a timing node and several control interface crates. Two timing nodes are configured in one beam line. Each node is responsible for the timing sequence, analog generation and feedback control for one ion source. The architecture and implementation of the timing system are presented in this paper.

Armor Tile Protection System of Neutral Beam Injector

In the Experimental Advanced Superconducting Tokamak (EAST) experiment, part of beam energy passes through the plasma and deposits in the interior wall of EAST. In order to protect the interior wall of EAST and obtain the temperature of it. A set of armor tile protection system (ATPS) based on PCI extensions for instrumentation was established. The function of ATPS is: (1) data acquisition; (2) anti false triggering; (3) output Digital Input Output alarm signal; The system is important to neutral beam injector even to whole EAST experiment. Experiments show that: the protection system fully meet the experimental requirements.

The Data Acquisition and Software Monitoring System for 4.6 GHz LHCD

In order to achieve high parameters operation on experimental advanced superconducting tokamak in future experiments, a new 6 MW/4.6 GHz lower hybrid current drive (LHCD) system has been finished in September 2013. The new system consists of 24 klystrons, and each is able to deliver up to 250 kW power at 4.6 GHz in continuous wave mode for 1000 s. It is a challenge to develop long pulse data acquisition for the LHCD system. The PCI eXtensions for Instrumentation based digitizers are adopted as the acquisition devices and an event-callback mechanism is formulated to fulfill the long pulse data acquisition. Various kinds of the acquired data are stored in unified text file format. A MySQL relational database based file server is launched to manage the text files while providing web service. Finally, a layer based monitoring subsystem is designed and proves feasible.

Temperature Measurement System of EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. The EAST NBI temperature measurement system (TCS) based on PCI extensions for instrumentation was established. It uses to measure the temperature of each heat loading component, to achieve the beam position and shape of the beam during the neutral beam injection. This system avoids the distortion and loss of experimental data during transmission. Experimental results show that the TCS is stable, reliable, and meets the experimental requirements fully.

A Control System Based on PXI Technology for the ECRH Power Supply of J-TEXT

A 100-kV/60-A high-voltage power supply (HVPS) is developed to supply the auxiliary heating system for a J-TEXT tokamak. This power supply is based on pulse step modulation (PSM) technology and consists of 144 switch modules. To fulfill the isolation, control, and protection requirements, a control system based on the PCI extensions for instrumentation is designed with the PSM technology for the HVPS. Experimental results show that the system has a good control performance and fast response. Thus, the proposed system meets the control requirement of the 100-kV/60-A HVPS.

The Real Implementation of ANFIS Channel Equalizer on the System of Software-Defined Radio

ABSTRACTThis paper deals with the usage of a combination of fuzzy system and artificial techniques, which are called adaptive neuro fuzzy inference system (ANFIS), in order to minimize the distance between the signal and SNR transmitting channel noise and then reduce the error rate of bit error rate (BER) transmission. The authors are focusing on a real implementation of ANFIS channel equalizer on software-defined radio (SDR) system working on PCI eXtensions for instrumentation (PXI) platform. This sophisticated modular measuring system consists of a vector signal generator RF VSG NI PXI-5670 and a vector signal analyzer RF VSA NI PXI-5661. Experimental results suggest that researched ANFIS equalizer embodies better BER values in comparison to commercially most common equalizers of the least mean square algorithm group. Moreover, the conducted experiments show that the usage of the SDR conception is very suitable for testing new principles in channel equalization field.

A digital long pulse integrator for EAST Tokamak

A digital integrator has been developed to be compatible with the long pulse plasma discharges on the Experimental Advanced Superconductor Tokamak (EAST), in which the induced signal is modulated by a chopper, and a field programmable gate array (FPGA) in the 16-bit digitizer is used to realize the digital integration in real time. After rectification and integration, the drift is almost linear and stable in controlled temperature, so a period of 50s is used to determine the linear drift rate for drift compensation. The integration data can be directly transferred to the reflective memory (RFM) card, which is installed in the same PCI eXtensions for Instrumentation (PXI) chassis, so the data transmission can be also done in real time. The test results show that the real time data transmission rate is up to 10kHz, the integration drift is typically less than 0.4uVs/s and drift performance is a little worse in real long pulse discharge, which can be reduced further by using more precise data acquisition.

Adaptive Fuzzy PID Force Control for a Prosthetic Hand

An adaptive fuzzy proportional-integral-derivative (PID) force control strategy for a prosthetic hand is presented. The classical PID controller is also applied on the prosthetic hand as comparison. The parameters of PID controller are firstly tuned by Cut and Try method. Then a fuzzy logic system is used to adjust those parameters on line. Real-time force control experiments are realized on LabVIEW and PXI (PCI eXtensions for Instrumentation) real-time (RT) platforms. A rigid object and a compliant object are grasped by the prosthesis respectively to test the performance of controllers. Experimental results indicate that the adaptive fuzzy PID force controller is more effective than PID controller.