Fast Short Circuit Type I Detection Method based on VGE-Monitoring
Herrmann, C.; Liu, X.; Lutz, J.; Basler, T.
2021 - English In this paper, a Short Circuit type I detection method based on the monitoring of the gate voltage is investigated. The proposed detection principle relies on an existing method, which was realized as an integrated solution before. A modified discrete circuit solution is introduced, developed and tested. Moreover, measurements and investigations on different packaging concepts and test conditions are performed. The overview of the functionality, reliability, and restraints of this method, as well as aspects of a supposed dynamic self-adaption feature, are discussed. Available in digital repository of ČVUT. Fast Short Circuit Type I Detection Method based on VGE-Monitoring

In this paper, a Short Circuit type I detection method based on the monitoring of the gate voltage is investigated. The proposed detection principle relies on an existing ...

Herrmann, C.; Liu, X.; Lutz, J.; Basler, T.
České vysoké učení technické v Praze, 2021

Measuring Transient I/V Turn-On Behavior of a Power MOSFET without a Current Sensor
Helmut, Dennis; Groos, Gerhard; Wachutka, Gerhard; Schrag, Gabriele
2021 - English Double pulse test (DPT) is usually used to characterize and verify turn-on/turn-off operation of power switches. Yet, new high frequency switching devices based on SiC and GaN technologies require much more elaborate DPT circuitry and sensing nodes compared to the established Si devices. Especially, suitable current sensors are challenging to realize and always limit the bandwidth. We propose a Transmission Line Pulsing (TLP)-based technique, which we call sensor gap TLP (sgTLP) and which is capable to monitor the transient currents and voltages during the turn-on sequence of a power MOSFET, without the need of a current sensor. The proposed sgTLP approach is compared to established TLP methods in two applications: the passive switching of a fast transient voltage suppression diode and the active switching of a Si power MOSFET. The novel sgTLP shows the same or better characteristics than both of the standard methods, but needs only one measurement, where standard TLP would need two separate methods. Especially, sgTLP detected rise times of 54 ps of a current and 52 ps of a voltage signal using a pulse duration of 100 ns. The measured characteristics of the MOSFET turnon reveals several inductive and capacitive coupling mechanisms that are not analyzable by the established TLP methods but become visible applying sgTLP. Available in digital repository of ČVUT. Measuring Transient I/V Turn-On Behavior of a Power MOSFET without a Current Sensor

Double pulse test (DPT) is usually used to characterize and verify turn-on/turn-off operation of power switches. Yet, new high frequency switching devices based on SiC and GaN technologies ...

Helmut, Dennis; Groos, Gerhard; Wachutka, Gerhard; Schrag, Gabriele
České vysoké učení technické v Praze, 2021

Singular Point Source MOS (S-MOS) Cell Concept
Rahimo, Munaf T. A.; Nistor, Iulian; Green, David
2021 - English A Singular Point Source MOS (S-MOS) cell concept suitable for power semiconductor MOS based devices is presented. The S-MOS differs from a standard Planar or Trench MOS cell in the manner by which the total channel width per device area is determined. The S-MOS cell channel width is defined as the peripheral length of a line running approximately along the N++ source and P channel junction which is situated on a single gated trench side-wall. The length of the line can be established from a singular point source implant for forming the N++ source region which corresponds to the shape of the N++/P junction. The total channel width will therefore depend on the total number of gated trench side- walls per chip. Despite a relatively short channel width obtained on a single trench side-wall, narrow mesa dimensions between adjacent trenches will provide an adequate number of cells for adjusting the total channel width as required for a given device performance. The S-MOS can be realized by simple manufacturing processes and presents an alternative approach for MOS cell layouts by decoupling critical design parameters (e.g., channel width, trench dimension and NPN transistor area). This flexibility can lead to lower overall losses, lower gate charge levels, improved switching robustness and controllability for different MOS based devices. Available in digital repository of ČVUT. Singular Point Source MOS (S-MOS) Cell Concept

A Singular Point Source MOS (S-MOS) cell concept suitable for power semiconductor MOS based devices is presented. The S-MOS differs from a standard Planar or Trench MOS cell in the manner by which ...

Rahimo, Munaf T. A.; Nistor, Iulian; Green, David
České vysoké učení technické v Praze, 2021

Integration of Comau robot into the Siemens Sinumerik 840D sl control system
Kuprin N.
2021 - English This article deals with the integration of Comau robotic arm into the Sinumerik system. The idea behind is to integrate a robotic arm into a machine tool as an exchangeable milling head. Such a solution would allow increasing a workspace of a machine tool by performing light machining operations with a robotic arm in places otherwise unreachable for conventional tools. Keywords: Comau; Sinumerik; robotic arm; PLC Available in digital repository of ČVUT. Integration of Comau robot into the Siemens Sinumerik 840D sl control system

This article deals with the integration of Comau robotic arm into the Sinumerik system. The idea behind is to integrate a robotic arm into a machine tool as an exchangeable milling head. Such a ...

Kuprin N.
České vysoké učení technické v Praze, 2021

Time Delay Model of the Turbine Pressure Water Conduit: Application to the off-the-grid regime control
Fišer J.; Zítek P.; Kuchař M.; Peichl A.; Kučera M.; Kulík P.; Vyhlídal T.
2021 - English The paper presents modeling the hydro-turbine governing system with delay in application to the turbo-machinery control. The delay originates from the wave phenomenon encountered in the pressure water conduit connected to the turbine. To facilitate the PID control tuning the turbine and conduit model is linearized and it results in linear time delay system referred to as the neutral system. Particularly, the disturbance rejection is achieved by the PID control response to varying power loads. Finally, the application example demonstrates the turbo-machinery control in the off-the-grid regime. Keywords: hydro turbine and conduit model; PID; turbo-machinery control; neutral system Available in digital repository of ČVUT. Time Delay Model of the Turbine Pressure Water Conduit: Application to the off-the-grid regime control

The paper presents modeling the hydro-turbine governing system with delay in application to the turbo-machinery control. The delay originates from the wave phenomenon encountered in the pressure water ...

Fišer J.; Zítek P.; Kuchař M.; Peichl A.; Kučera M.; Kulík P.; Vyhlídal T.
České vysoké učení technické v Praze, 2021

Geodesic ray-tracing in white matter fiber crossing region using decomposition of 4th order tensor
Kaushik S.; Tsegey T.; Bansal A.; Slovak J.
2021 - English The streamline methods in Diffusion tensor imaging (DTI) use principal eigenvectors for tracking white matter fibers. In comparison, the geodesics in a multivalued ray-tracing method are closer to the actual underlying white matter fibers. This method provides multiple solutions in the form of geodesics in a Riemannian space. These geodesics are robust in tracking high curvature structures in the presence of noise. In the DTI modality, the 2nd order tensor fails to model the heterogeneous regions, e.g., crossing/merging fibers. Therefore, the ray-tracing method is limited to guide the geodesics in these regions. This work, as a first step, utilizes 4th order tensor approximation for the white matter regions. Subsequently, a non-linear optimization is performed to decompose 4th order tensors into multiple 2nd order tensors keeping their symmetric positive definite property. We are using the initial fiber directions from the diagonal components of the 4th order tensor and use the 4th order tensor decomposition for fiber tracking. The experimental results on synthetic images show that geodesics can traverse in heterogeneous and high curvature structures. Keywords: HARDI; tensors; fiber tracking Available in digital repository of ČVUT. Geodesic ray-tracing in white matter fiber crossing region using decomposition of 4th order tensor

The streamline methods in Diffusion tensor imaging (DTI) use principal eigenvectors for tracking white matter fibers. In comparison, the geodesics in a multivalued ray-tracing method are closer to the ...

Kaushik S.; Tsegey T.; Bansal A.; Slovak J.
České vysoké učení technické v Praze, 2021

Contribution to three problems of nonlinear acoustics
Červenka, Milan
2021 - English Available in digital repository of ČVUT. Contribution to three problems of nonlinear acoustics

Červenka, Milan
České vysoké učení technické v Praze, 2021

Hollow-core optical fibers for sensing and communications
Komanec, Matěj
2021 - English Hollow-core optical fibers represent the state-of-the-art in fiber optics and are on the verge of surpassing the loss performance of standard single-mode fibers in the very near future. Apart from low loss, they bring high-power delivery possibilities, mid-infrared guidance even when made of silica and numerous other advantages. Nevertheless, their incorporation into standard fiber-optic systems is desired. In my habilitation thesis I present the development of a novel type of hollow-core fiber interconnection, based on the fiber array approach which led to record-low insertion loss, negligible back reflections and higher-order mode suppression. Our interconnection technique is then demonstrated in Fabry-Perot interferometer and microwave photonics applications. Keywords: Photonic crystal fibers; hollow-core optical fibers; coupling methods; fiber interconnections; Fabry-Perot interferometer; microwave photonics Available in digital repository of ČVUT. Hollow-core optical fibers for sensing and communications

Hollow-core optical fibers represent the state-of-the-art in fiber optics and are on the verge of surpassing the loss performance of standard single-mode fibers in the very near future. Apart from ...

Komanec, Matěj
České vysoké učení technické v Praze, 2021

Portability of the thermo-mechanical compensation model of the milling center
Straka M.; Mareš M.
2021 - English Thermo-mechanical errors of machine tools (MT) are important element in inaccuracies of machined workpieces. In the past few decades, thermal errors have been successfully reduced by techniques of software compensation. For example, the multiple linear regression analysis, the finite element method, the neural network or the transfer function (TF) are used. Approximation model based on dynamic method of TF is used for compensation thermal errors in this publication. The approach respects basic mechanisms of heat transfer in the MT structures. Every single piece of produced MT is original due to manufacturing inaccuracies of MT compo-nents, assembly process (different preloads in bolts, deviation in the assembly and seating of components, etc.) or working environ-ment of the MT (e.g. air-conditioned or common factory hall, etc.). Usually, MT producers offer the same type of the MT equipped with different components (e.g. spindle units) which leads to further differences in thermo-mechanical behaviour. The aim of the article is to define conditions and examine issues of transfer of existing thermal error compensation model between several machines of the same product line; taking into account manufacturing and assembly inaccuracies and changes in working environment. Selected machines were tested during non-stationary activity of the main heat sources: different spindle units and two linear axis movements. Keywords: thermal errors; portability; software compensation Available in digital repository of ČVUT. Portability of the thermo-mechanical compensation model of the milling center

Thermo-mechanical errors of machine tools (MT) are important element in inaccuracies of machined workpieces. In the past few decades, thermal errors have been successfully reduced by techniques of ...

Straka M.; Mareš M.
České vysoké učení technické v Praze, 2021

Unsupervised Construction of Task-Specific Datasets for Object Re-identification
Pulc P.; Holeňa M.
2021 - English In the last decade, we have seen a significant uprise of deep neural networks in image processing tasks and many other research areas. However, while various neural architectures have successfully solved numerous tasks, they constantly demand more and more processing time and training data. Moreover, the current trend of using existing pre-trained architectures just as backbones and attaching new processing branches on top not only increases this demand but diminishes the explainability of the whole model. Our research focuses on combinations of explainable building blocks for the image processing tasks, such as object tracking. We propose a combination of Mask R-CNN, state-of-the-art object detection and segmentation neural network, with our previously published method of sparse feature tracking. Such a combination allows us to track objects by connecting detected masks using the proposed sparse feature tracklets. However, this method cannot recover from complete object occlusions and has to be assisted by an object re-identification. To this end, this paper uses our feature tracking method for a slightly different task: an unsupervised extraction of object representations that we can directly use to fine-tune an object re-identification algorithm. As we have to use objects masks already in the object tracking, our approach utilises the additional information as an alpha channel of the object representations, which further increases the precision of the re-identification. An additional benefit is that our fine-tuning method can be employed even in a fully online scenario. Keywords: Fine-tuning of Object Re-identification; Multiple Object Tracking; Hierarchical Sparse Feature Tracking Available in digital repository of ČVUT. Unsupervised Construction of Task-Specific Datasets for Object Re-identification

In the last decade, we have seen a significant uprise of deep neural networks in image processing tasks and many other research areas. However, while various neural architectures have successfully ...

Pulc P.; Holeňa M.
České vysoké učení technické v Praze, 2021