Converter Board Research Articles

A heterodyne interferometer with periodic nonlinearities smaller than ±10 pm

The PTB developed a new optical heterodyne interferometer in the context of the European joint research project ‘Nanotrace’. A new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized. Furthermore, the interferometer has the resolution of a double-path interferometer, compensates for possible angle variations between the mirrors and the interferometer optics and offers a minimal path difference between the reference and the measurement arm. Additionally, a new heterodyne phase evaluation based on an analogue to digital converter board with embedded field programmable gate arrays was developed, providing a high-resolving capability in the single-digit picometre range. The nonlinearities were characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods of the optical interferometer. Assuming an error-free x-ray interferometer, the nonlinearities are considered to be the deviation of the measured displacement from a best-fit line. For the proposed interferometer, nonlinearities smaller than ±10 pm were observed without any quadrature fringe correction.

Phase measurement of various commercial heterodyne He–Ne-laser interferometers with stability in the picometer regime

In order to be able to resolve displacements of a picometer with widely used commercially available heterodyne interferometers, an advanced phase meter was developed at PTB. Key to this level of accuracy is the use of a state-of-the-art analogue-to-digital converter (ADC) board enabling the implementation of a phase-evaluation method by using embedded field programmable gate arrays. Experimental results obtained with commercially available heterodyne laser interferometer components prove that the proposed phase-evaluation procedure is capable of interpolating an optical fringe down into the picometer regime. The phase evaluation was moreover extended to track simultaneously two heterodyne beat frequencies with only two photodetectors and ADCs. Potential limitations of the long-term stability of heterodyne interferometers are discussed. The phase meter was tested, has been readily applied, can be easily adapted and is therefore to be used in a wide field of applications.

One Test System Design of Static Stiffness for Machine Tools

Computer is regarded as a center of signal detection, data processing and control in this system, accompanied by precision displacement sensors, pressure sensors and stepper motors and drives. Realize the transition of analog to digital with A/D converter board by VB6.0, and load simulation device steady and uniform by stepper motor, at the same time realize the functions of data calculation processing, storage, querying and sample curve drawing. The experimental results shows that the system has the advantages of a high degree of automation, high test efficiency, high precision, high reliability, stability test performance.

Integrated High-Frequency Power Converters Based on GaAs pHEMT: Technology Characterization and Design Examples

The potential of GaAs pHEMT technology for high-frequency power-switching applications is discussed within the context of integrated power supplies for portable wireless systems. Various technology considerations are presented, including the optimization of the power-switching transistor and passives integration. Two design examples for integrated dc-dc converters are implemented in a 0.5-μm GaAs E/D pHEMT process. The first uses coupled inductors to reduce the current ripple and enhance the dynamic performance of the converter. The two-phase, 0.5 A/phase converter occupies 2 mm × 2.1 mm without the output network. An 8.7-nH filter coupled inductor is implemented in 65-μm-thick top copper metal layer, and flip-chip bonded to the dc-dc converter board. The presented converter converts 4.5-V input to 3.3-V output at 150-MHz switching frequency with a measured power efficiency of 84%, which is one of the highest efficiencies reported to date for similar current/voltage ratings. The second example is a hysteric controlled, 100-MHz switching frequency single-phase GaAs pHEMT buck converter designed to drive power amplifier loads. The design can deliver up to 37-dB·m output power and has a peak efficiency of 88% and a 3-dB bandwidth of 14.5 MHz.

A Cryogenic Dc-Dc Power Converter for a 100kW Synchronous HTS Generator at Liquid Nitrogen Temperatures

Abstract A dc-dc converter has been developed for retrofitting inside the vacuum space of the HTS rotor of a synchronous generator. The heavy copper sections of the current leads used for energising the HTS field winding were replaced by cryogenic power electronics; consisting of the converter and a rotor control unit. The converter board was designed using an H-bridge configuration with two 5A rated wires connecting the cryogenic boards to the stator control board located on the outside of the generator and drawing power from a (5A, 50 V) dc power source. The robustness of converter board was well demonstrated when it was powered up from a cold start at 82K. When charging the field winding with moderate currents (30A), the heat in-leak to the ‘cold’ rotor core was only 2W. It continued to function down to 74K, surviving several quenches. However, the quench protection function failed when injecting 75A into the field winding, resulting in the burn out of one of the DC-link capacitors. The magnitudes of the critical currents measured with the original current leads were compared to the quench currents, which was defined as the current which triggered quench protection protocol. The difference between the two currents was rather large, (∼20A). However, additional measurements using a single HTS coil in liquid nitrogen found that this reduction should not be so dramatic and in the region of 4A. Our conclusions identified the converter's switching voltage and its operating frequency as two parameters, which could have contributed to lowering the quench current. Magnetic fields and eddy currents are expected to be more prominent the field winding and its impact on the converter also need further investigation.

A high dynamic range data acquisition system for a solid-state electron electric dipole moment experiment

We have built a high precision (24-bit) data acquisition (DAQ) system capable of simultaneously sampling eight input channels for the measurement of the electric dipole moment of the electron. The DAQ system consists of two main components: a master board for DAQ control and eight individual analog-to-digital converter (ADC) boards for signal processing. This custom DAQ system provides galvanic isolation of the ADC boards from each other and the master board using fiber optic communication to reduce the possibility of ground loop pickup and attain ultimate low levels of channel cross-talk. In this paper, we describe the implementation of the DAQ system and scrutinize its performance.

Grid Connected Based Six-Pulse Converter Applied A Self-Excited Induction Generator for Wind Turbine Applications

Abstract This paper the electrical power conversion system presents developed for a self-excited induction generator for wind turbine applications. In the wind energy conversion system a self-excited induction generator converts the mechanical energy into electrical energy. A B6 rectifier and inductor are utilized to maintain constant dc link current. The average power is converted entirely by the six-pulse converter, it's consists of a B6 current-source inverters. Line side current-source inverter supply currents into the utility line by regulating the dc link voltage. The active power is controlled by firing angle of converter with operated at inverter mode. The performance improvement of this proposed system by experiment using a 1 kW four pole self excited induction generator. The overall control system is implemented on six-pulse converter board. Experimental results are illustrated in order to validate performance of the proposed system.

High efficiency, high switching speed, AlGaAs/GaAs P-HEMT DC–DC converter for integrated power amplifier modules

This paper presents a high efficiency, high switching frequency DC---DC buck converter in AlGaAs/GaAs technology, targeting integrated power amplifier modules for wireless communications. The switch mode, inductor load DC---DC converter adopts an interleaved structure with negatively coupled inductors. Analysis of the effect of negative coupling on the steady state and transient response of the converter is given. The coupling factor is selected to achieve a maximum power efficiency under a given duty cycle with a minimum penalty on the current ripple performance. The DC---DC converter is implemented in 0.5 μm GaAs p-HEMT process and occupies 2 × 2.1 mm2 without the output network. An 8.7 nH filter inductor is implemented in 65 μm thick top copper metal layer, and flip chip bonded to the DC---DC converter board. The integrated inductor achieves a quality factor of 26 at 150 MHz. The proposed converter converts 4.5 V input to 3.3 V output for 1 A load current under 150 MHz switching frequency with a measured power efficiency of 84%, which is one of the highest efficiencies reported to date for similar current/voltage ratings.

Self-priming Hemodynamic Reservoir and Inline Flow Meter for a Cardiopulmonary Bypass Simulation

Simulator exercises are used at Midwestern University to augment academic and laboratory training toward consolidating particular skills, increasing situation awareness, and preparing the student for practice within the team environment of an operating room. This paper describes an enhanced cardiopulmonary bypass simulator consisting of a self-priming hemodynamic reservoir that includes an inline flow meter. A typical cardiopulmonary bypass adult perfusion circuit was assembled using a roller pump console and integrated oxygenator/heat exchanger/reservoir and primed with 2 liters of water. For patient simulation, a soft-sided reservoir bag was mounted onto an inclined platform. A 1-liter soft-sided bag was placed just above the reservoir, providing an overflow reservoir. The priming line extended to the head of the mannequin. The arterial, venous, and suction lines extended through the open chest. The primed perfusion circuit was connected to ports on the filled reservoir bag. To test the patient simulation, the arterial pump output was adjusted to flow rates ranging from 1–7 liters per minute, with a complete interruption (to zero flow) between each test run. An inline flow meter was added to the bypass circuit and an analog to digital converter board was used to pass flow data into the computer-based simulation program. The use of an inclined hemodynamic reservoir bag proved to be self-priming and functional without problems over a wide range of flows tested. By including a reservoir with the mannequin, plus processing and displaying real-time flow data using the CPB-Sim simulation program, a higher fidelity and more realistic simulation experience was created.

A Real-Time Monitoring System Using a Multimodal Sensor with an Electrical Conductivity Sensor and a Temperature Sensor for Cow Health Control

A multimodal sensor composed of an electrical conductivity (EC) sensor and a temperature sensor on the same Si chip was successfully fabricated using compatible complementary metal oxide semiconductor (CMOS) technology. The EC sensor measured the electrical conductivity between Pt electrodes, and the temperature sensor measured the forward voltage of a p–n junction diode. We confirmed the output signal in a wide dynamic range of ECs. For real-time measurement in the rumen of cows, a wireless system was fabricated. The system included a sensor, a battery, an antenna, an analog signal-processing circuit board, an AC-to-DC converter board, and a receiver–transmitter board. We adjusted the wireless system design with focus on the measurement range to adapt the system to the rumen. Real-time and simultaneous measurements of EC and temperature in the rumen using the multimodal sensor unit were performed. The wireless system successfully received signals continuously, and enabled the measurement of the rumen conditions in real time.

Iqueye, a single photon-counting photometer applied to the ESO new technology telescope

Context. A new extremely high speed photon-counting photometer, Iqueye, has been installed and tested at the New Technology Telescope, in La Silla. Aims. This instrument is the second prototype of a “quantum” photometer being developed for future Extremely Large Telescopes of 30–50 m aperture. Methods. Iqueye divides the telescope aperture into four portions, each feeding a single photon avalanche diode. The counts from the four channels are collected by a time-to-digital converter board, where each photon is appropriately time-tagged. Owing to a rubidium oscillator and a GPS receiver, an absolute rms timing accuracy better than 0.5 ns during one-hour observations is achieved. The system can sustain a count rate of up to 8 MHz uninterruptedly for an entire night of observation. Results. During five nights of observations, the system performed smoothly, and the observations of optical pulsar calibration targets provided excellent results.

Evaluating the performance of microbial fuel cells powering electronic devices

A microbial fuel cell (MFC) is capable of powering an electronic device if we store the energy in an external storage device, such as a capacitor, and dispense that energy intermittently in bursts of high-power when needed. Therefore its performance needs to be evaluated using an energy-storing device such as a capacitor which can be charged and discharged rather than other evaluation techniques, such as continuous energy dissipation through a resistor. In this study, we develop a method of testing microbial fuel cell performance based on storing energy in a capacitor. When a capacitor is connected to a MFC it acts like a variable resistor and stores energy from the MFC at a variable rate. In practice the application of this method to testing microbial fuel cells is very challenging and time consuming; therefore we have custom-designed a microbial fuel cell tester (MFCT). The MFCT evaluates the performance of a MFC as a power source. It uses a capacitor as an energy storing device and waits until a desired amount of energy is stored then discharges the capacitor. The entire process is controlled using an analog-to-digital converter (ADC) board controlled by a custom-written computer program. The utility of our method and the MFCT is demonstrated using a laboratory microbial fuel cell (LMFC) and a sediment microbial fuel cell (SMFC). We determine (1) how frequently a MFC can charge a capacitor, (2) which electrode is current-limiting, (3) what capacitor value will allow the maximum harvested energy from a MFC, which is called the “optimum charging capacitor value,” and (4) what capacitor charging potential will harvest the maximum energy from a MFC, which is called the “optimum charging potential.” Using a LMFC we find that (1) the time needed to charge a 3-F capacitor from 0 to 500 mV is 108 min, (2) the optimum charging capacitor value is 3 F, and (3) the optimum charging potential is 300 mV. Using a SMFC we find that (1) the time needed to charge a 3-F capacitor from 0 to 500 mV is 5 min, (2) the optimum charging capacitor value is 3 F, and (3) the optimum charging potential is 500 mV. Our results demonstrate that the developed method and the MFCT can be used to evaluate and optimize energy harvesting when a MFC is used with a capacitor to power wireless sensors monitoring the environment.

High-resolution voltage reference for magnet power supply

This paper presents a high-resolution voltage reference which is suitable for building high-precision magnet power supplies for accelerators. It consists of digital signal processor, field programmable gate array, and two digital-to-analog converter (DAC) boards. The DAC board uses two commercial 16-bit-D/A converters and an analog signal processing circuit to achieve a resolution higher than 20-bit. The proposed voltage reference has a resolution of 20-bit (1 ppm) for the +10 V full scale. The short- and long-term stabilities are ~1 and 5 ppm, respectively. The controllability and reproducibility of the output voltage to a step input were ~1 ppm (10 μV). The equivalent bandwidth of the voltage reference was ~5 kHz. These experimental results show that the proposed voltage reference may be applied to many other systems which require a high-resolution and cost-effective voltage reference with a good long-term stability. The voltage reference can be interfaced with the Ethernet (including EPICS), CAN, and RS232C.

A multi-threshold sampling method for TOF-PET signal processing

As an approach to realizing all-digital data acquisition for positron emission tomography (PET), we have previously proposed and studied a multi-threshold sampling method to generate samples of a PET event waveform with respect to a few user-defined amplitudes. In this sampling scheme, one can extract both the energy and timing information for an event. In this paper, we report our prototype implementation of this sampling method and the performance results obtained with this prototype. The prototype consists of two multi-threshold discriminator boards and a time-to-digital converter (TDC) board. Each of the multi-threshold discriminator boards takes one input and provides up to eight threshold levels, which can be defined by users, for sampling the input signal. The TDC board employs the CERN HPTDC chip that determines the digitized times of the leading and falling edges of the discriminator output pulses. We connect our prototype electronics to the outputs of two Hamamatsu R9800 photomultiplier tubes (PMTs) that are individually coupled to a 6.25 × 6.25 × 25 mm 3 LSO crystal. By analyzing waveform samples generated by using four thresholds, we obtain a coincidence timing resolution of about 340 ps and an ∼ 18 % energy resolution at 511 keV. We are also able to estimate the decay-time constant from the resulting samples and obtain a mean value of 44 ns with an ∼ 9 ns FWHM. In comparison, using digitized waveforms obtained at a 20 GSps sampling rate for the same LSO/PMT modules we obtain ∼ 300 ps coincidence timing resolution, ∼ 14 % energy resolution at 511 keV, and ∼ 5 ns FWHM for the estimated decay-time constant. Details of the results on the timing and energy resolutions by using the multi-threshold method indicate that it is a promising approach for implementing digital PET data acquisition.

Quadrature Bridge for $R$– $C$ Comparisons Based on Polyphase Digital Synthesis

A coaxial quadrature bridge based on digital synthesis has been developed. The bridge compares two resistance standards (having nominal resistance R) with two capacitance standards (nominal capacitance C) at an angular frequency omega (such that omegaRC ap 1). All standards are defined as two terminal-pair impedances. All voltages and currents employed in the bridge are generated by a multiphase direct digital synthesizer constructed around a personal computer digital-to-analog converter (DAC) board and a set of buffer amplifiers; the number of electromagnetic devices has been kept to a minimum. The purpose of the bridge is to be employed in the realization of the farad unit, starting from the representation of ohm given by the quantum Hall effect. The relative bridge accuracy during the calibration of 1000-pF capacitors in terms of 100-kOmega resistors at omega = 10 krad ldr s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> has been verified to be less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> ; preliminary uncertainty assignments give a transfer uncertainty of a few parts in 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> .

New USB-based 3D digital echo sounder system for mapping and assessing fish and aquatic plants

A recently developed echo sounder with a global positioning system (GPS) receiver can display both the boat position and echo gram. However, this information is displayed in different views. In this paper, we present a new digital three-dimensional (3D) echo sounder system comprising a traditional analog echo sounder, GPS receiver, notebook personal computer (PC), and a low-cost, compact, self-developed universal serial bus (USB)-based analog-to-digital (A/D) converter board. Multiple echo views can simultaneously display various desired targets more clearly than the view in a traditional analog echo sounder. The newly developed analysis software can precisely extract the information related to bottom depth, plants, and fish schools from the echoes. By combining the acoustic and position data, the system can map both the fish and plant echoes on the 3D sea bed generated from the extracted bottom depth. This system has been proved to be useful in observing the 3D and wide-area distribution of both fishes and aquatic plants and in studying habitat parameters in aquatic ecosystems. A notebook PC equipped with the self-developed USB-based A/D converter board is capable of transforming any traditional analog echo sounder into a high-performance 3D digital echo sounder.

A rapid algorithm for processing digital physiologic signals: Application to skeletal muscle contractions

Quantifying mechanical output is fundamental to understanding metabolism that fuels muscle contraction and more recent attempts to understand signal transduction and gene regulation. The latter requires long-term application of exercise protocols that result in large amounts of data on muscle performance. The purpose of this study was to develop software for automated quantification of skeletal muscle contractions. An in situ mouse sciatic nerve stimulation model was used to produce contractions over a broad range of frequencies and recorded as both digital and analog signals using a PC analog to digital converter board and chart recorder, respectively. Spectral analysis of the noise components formed the basis for designing a smoothing Chebyshev filter. Algorithms implemented in custom software identified twitches and estimated baseline levels from the smoothed signal. The time to peak force, peak force, tension-time integral, and half-relaxation time were determined for each twitch after baseline correction. The automated results were compared to those obtained from manual measurements of the analog signal. Bland–Altman analysis of the parameters computed from digital signals compared with the corresponding measurements by manual planometry demonstrates the agreement of the digital processing algorithm with planometry over a wide range of twitch characteristics. This program may also be used to study the mechanics of other preparations from isolated muscles, human proximal limb performance, and other digital physiologic signals. Adaptation of the filter function is required to apply the analysis to another experimental apparatus with differing noise characteristics. A full version of the program and instructions for its use are available for download at www.rad.msu.edu.

The Dynamic Characteristic of Printed Circuit Board with the Use of the Concept of Simplified Representative Volume Elements

PCB (Printed Circuit Board)s are designed in various sizes and shapes, use variety of processes and materials, and perform a variety of electrical, structural, and some times thermal functions. The major elements of PCBs are the fabric, the resin, and the metal foil (usually copper). The auxiliary elements are the adhesion promoters or treatments that are applied to the fabric and to the copper to assure maximum adhesion of the resin to the fabric and to the copper. Each copper layer has complicated and different pattern to correctly operate for its mission. In that case, the stiffness of PCBs are affected by the copper layers. By reasoning of this complicated copper layer pattern, it is difficult to determine the PCB stiffness. SAR (Solar Array Regulator) for Korea Leo Earth Observation & Science Satellites Program uses two PCBs of different types and sizes. These PCBs are composed of the resin system and copper layers, and not used the fabric. For this study, arm converter board applied to the SAR components is considered. In this study, the methodology of calculation of the PCB stiffness for SAR component is suggested considering the concept of simplified representative volume element and this property will be correlated with the vibration test results.

Design and test of prototype boards for the L1 calorimeter trigger upgrade at the D0 experiment

This paper presents the development and test of some of the electronic boards that have been designed for the upgrade of the L1 calorimeter trigger at the D0 experiment. The analog to digital converter and filter board (ADF) digitizes 32 calorimeter channels, applies digital filtering, and sends data to the next processing stage via 2 Gb/s links. The board is designed for sustained operation at 7.57 MHz with an end-to-end latency of less than ~1 mus. In order to test the high-speed output links of the ADF board, we made a tester that comprises a custom made Channel Link receiver card. To connect a prototype ADF board to the D0 detector without disturbing the existing trigger system, we designed a splitter board that duplicates the analog signals from eight calorimeter channels. The serial command link distribution card (SCLD) is designed to accurately distribute synchronization signals to the 80 ADF boards of the final system. We made single channel versions of the ADF and SCLD boards. These cards run in a simple desktop PC environment and are helpful for tests and collaborative work. We describe the hardware, firmware and software aspects of the various developments and show the operation of the different boards. We present performance measurements made on the prototype ADF board, and explain how we defined the production model of this board

A repetitive-based controller for the boost converter to compensate the harmonic distortion of the output Voltage

A novel repetitive based-control strategy is proposed for the pulsewidth modulated (PWM) boost converter to compensate the output voltage ripple due to the harmonic distortion present in the input voltage. Repetitive control has shown to be a useful tool for tracking of periodic reference signals and for compensation of periodic disturbances, in other words, for harmonic compensation. The structure of the proposed controller is preserved as close as possible to the conventional one, which includes outer and inner control loops. Thus, in the proposed controller, the repetitive strategy appears as a refinement term added to the inner control loop. We show that the repetitive strategy can be built using a single analog delay integrated circuit, thus, simplifying enormously the implementation. The repetitive strategy is able to cancel almost every remaining harmonic distortion component while maintaining an acceptable dynamical performance and without inclusion of additional hardware in the power stage. Experimental results on a boost converter board, using a poorly regulated voltage source, are presented to assess the performance of our approach.