The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Gorazd Stumberger - One of the best experts on this subject based on the ideXlab platform.

  • Artificial Neural Network Applied for Detection of Magnetization Level in the Magnetic Core of a Welding Transformer
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Klemen Deželak, B. Klopčič, Joze Pihler, Gorazd Stumberger, Drago Dolinar
    Abstract:

    This paper deals with the detection of Saturation in the magnetic Core of a welding transformer which is a part of a middle-frequency direct current (MFDC) resistance spot welding system (RSWS). It consists of an input rectifier, which produces dc bus voltage, an inverter, a welding transformer, and a full-wave rectifier that is mounted on the output of a transformer. During normal RSWS operation welding transformer's magnetic Core can become saturated due to the unbalanced resistances of both transformer secondary windings and different characteristics of output rectifier diodes, which causes current spikes and over-current protection switch-off of the entire system. In order to prevent Saturation of the transformer magnetic Core, the RSWS control must detect that the magnetic Core is approaching the saturated region. The aim of this paper is to present a reliable method for detection of magnetic Core Saturation that does not require an additional sensor. It is based on the artificial neural network (ANN). Its input is the measured primary current of the welding transformer. The applied ANN is trained to recognize the waveform of the current spikes in the primary current caused by the magnetic Core Saturation, which is used for magnetization level detection.

  • Prevention of Iron Core Saturation in Multi-Winding Transformers for DC-DC Converters
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Gorazd Stumberger, B. Klopčič, Klemen Deželak, Drago Dolinar
    Abstract:

    This paper deals with prevention of Saturation in the iron Core of a multi-winding transformer. It is a substantial part of dc-dc converters used in resistance spot welding systems. The discussed resistance spot welding system consists of a semiconductor input converter, a single-phase welding transformer with one primary coil and two secondary coils, and a full-wave output rectifier connected to the transformer's secondary coils. The paper shows that the interaction among magnetically nonlinear behavior of the iron Core combined with unbalanced parameters of the circuits with the two transformer's secondary coils can cause iron Core Saturation even when elements connected to coils are passive elements. The first part of the paper focuses on analysis of Saturation phenomena in multi-winding transformers. It is performed on specially designed laboratory transformer composed of the iron Core in the form of two C-shaped segments and modular coils used to form the single-coil primary winding and two-coil secondary winding. Knowledge acquired on the laboratory transformer is applied to develop two different solutions for active prevention of the iron Core Saturation in multi-winding welding transformers. Both solutions are presented in the second part of the paper.

  • Improvement of spot welding control system
    Proceedings of 14th International Power Electronics and Motion Control Conference EPE-PEMC 2010, 2010
    Co-Authors: Drago Dolinar, B. Klopčič, Gorazd Stumberger
    Abstract:

    This paper deals with the control improvement of a middle-frequency resistance spot welding system. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed control assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core.

  • Advanced control of a resistance spot welding system
    IEEE Transactions on Power Electronics, 2008
    Co-Authors: B. Klopčič, Drago Dolinar, Gorazd Stumberger
    Abstract:

    This paper deals with a middle-frequency resistance spot welding system. It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The welding current at the full-wave rectifier output is normally controlled by the pulse width modulated primary voltage of the transformer supplied by the input converter. The unequal ohmic resistances of the two transformer's secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic Saturation which, consequently, causes the unwanted spikes in the transformer's primary current and over-current protection switch-off. This disadvantage of classical spot welding systems is completely eliminated by the proposed advanced hysteresis controller (AHC), which keeps transformer iron Core Saturation within prescribed bounds regardless of how unequal the ohmic resistances and diodes' characteristics in the transformer's secondary circuits are. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed AHC assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core. © 2007 IEEE.

B. Klopčič - One of the best experts on this subject based on the ideXlab platform.

  • Artificial Neural Network Applied for Detection of Magnetization Level in the Magnetic Core of a Welding Transformer
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Klemen Deželak, B. Klopčič, Joze Pihler, Gorazd Stumberger, Drago Dolinar
    Abstract:

    This paper deals with the detection of Saturation in the magnetic Core of a welding transformer which is a part of a middle-frequency direct current (MFDC) resistance spot welding system (RSWS). It consists of an input rectifier, which produces dc bus voltage, an inverter, a welding transformer, and a full-wave rectifier that is mounted on the output of a transformer. During normal RSWS operation welding transformer's magnetic Core can become saturated due to the unbalanced resistances of both transformer secondary windings and different characteristics of output rectifier diodes, which causes current spikes and over-current protection switch-off of the entire system. In order to prevent Saturation of the transformer magnetic Core, the RSWS control must detect that the magnetic Core is approaching the saturated region. The aim of this paper is to present a reliable method for detection of magnetic Core Saturation that does not require an additional sensor. It is based on the artificial neural network (ANN). Its input is the measured primary current of the welding transformer. The applied ANN is trained to recognize the waveform of the current spikes in the primary current caused by the magnetic Core Saturation, which is used for magnetization level detection.

  • Prevention of Iron Core Saturation in Multi-Winding Transformers for DC-DC Converters
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Gorazd Stumberger, B. Klopčič, Klemen Deželak, Drago Dolinar
    Abstract:

    This paper deals with prevention of Saturation in the iron Core of a multi-winding transformer. It is a substantial part of dc-dc converters used in resistance spot welding systems. The discussed resistance spot welding system consists of a semiconductor input converter, a single-phase welding transformer with one primary coil and two secondary coils, and a full-wave output rectifier connected to the transformer's secondary coils. The paper shows that the interaction among magnetically nonlinear behavior of the iron Core combined with unbalanced parameters of the circuits with the two transformer's secondary coils can cause iron Core Saturation even when elements connected to coils are passive elements. The first part of the paper focuses on analysis of Saturation phenomena in multi-winding transformers. It is performed on specially designed laboratory transformer composed of the iron Core in the form of two C-shaped segments and modular coils used to form the single-coil primary winding and two-coil secondary winding. Knowledge acquired on the laboratory transformer is applied to develop two different solutions for active prevention of the iron Core Saturation in multi-winding welding transformers. Both solutions are presented in the second part of the paper.

  • Improvement of spot welding control system
    Proceedings of 14th International Power Electronics and Motion Control Conference EPE-PEMC 2010, 2010
    Co-Authors: Drago Dolinar, B. Klopčič, Gorazd Stumberger
    Abstract:

    This paper deals with the control improvement of a middle-frequency resistance spot welding system. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed control assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core.

  • Advanced control of a resistance spot welding system
    IEEE Transactions on Power Electronics, 2008
    Co-Authors: B. Klopčič, Drago Dolinar, Gorazd Stumberger
    Abstract:

    This paper deals with a middle-frequency resistance spot welding system. It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The welding current at the full-wave rectifier output is normally controlled by the pulse width modulated primary voltage of the transformer supplied by the input converter. The unequal ohmic resistances of the two transformer's secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic Saturation which, consequently, causes the unwanted spikes in the transformer's primary current and over-current protection switch-off. This disadvantage of classical spot welding systems is completely eliminated by the proposed advanced hysteresis controller (AHC), which keeps transformer iron Core Saturation within prescribed bounds regardless of how unequal the ohmic resistances and diodes' characteristics in the transformer's secondary circuits are. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed AHC assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core. © 2007 IEEE.

Drago Dolinar - One of the best experts on this subject based on the ideXlab platform.

  • Artificial Neural Network Applied for Detection of Magnetization Level in the Magnetic Core of a Welding Transformer
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Klemen Deželak, B. Klopčič, Joze Pihler, Gorazd Stumberger, Drago Dolinar
    Abstract:

    This paper deals with the detection of Saturation in the magnetic Core of a welding transformer which is a part of a middle-frequency direct current (MFDC) resistance spot welding system (RSWS). It consists of an input rectifier, which produces dc bus voltage, an inverter, a welding transformer, and a full-wave rectifier that is mounted on the output of a transformer. During normal RSWS operation welding transformer's magnetic Core can become saturated due to the unbalanced resistances of both transformer secondary windings and different characteristics of output rectifier diodes, which causes current spikes and over-current protection switch-off of the entire system. In order to prevent Saturation of the transformer magnetic Core, the RSWS control must detect that the magnetic Core is approaching the saturated region. The aim of this paper is to present a reliable method for detection of magnetic Core Saturation that does not require an additional sensor. It is based on the artificial neural network (ANN). Its input is the measured primary current of the welding transformer. The applied ANN is trained to recognize the waveform of the current spikes in the primary current caused by the magnetic Core Saturation, which is used for magnetization level detection.

  • Prevention of Iron Core Saturation in Multi-Winding Transformers for DC-DC Converters
    IEEE Transactions on Magnetics, 2010
    Co-Authors: Gorazd Stumberger, B. Klopčič, Klemen Deželak, Drago Dolinar
    Abstract:

    This paper deals with prevention of Saturation in the iron Core of a multi-winding transformer. It is a substantial part of dc-dc converters used in resistance spot welding systems. The discussed resistance spot welding system consists of a semiconductor input converter, a single-phase welding transformer with one primary coil and two secondary coils, and a full-wave output rectifier connected to the transformer's secondary coils. The paper shows that the interaction among magnetically nonlinear behavior of the iron Core combined with unbalanced parameters of the circuits with the two transformer's secondary coils can cause iron Core Saturation even when elements connected to coils are passive elements. The first part of the paper focuses on analysis of Saturation phenomena in multi-winding transformers. It is performed on specially designed laboratory transformer composed of the iron Core in the form of two C-shaped segments and modular coils used to form the single-coil primary winding and two-coil secondary winding. Knowledge acquired on the laboratory transformer is applied to develop two different solutions for active prevention of the iron Core Saturation in multi-winding welding transformers. Both solutions are presented in the second part of the paper.

  • Improvement of spot welding control system
    Proceedings of 14th International Power Electronics and Motion Control Conference EPE-PEMC 2010, 2010
    Co-Authors: Drago Dolinar, B. Klopčič, Gorazd Stumberger
    Abstract:

    This paper deals with the control improvement of a middle-frequency resistance spot welding system. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed control assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core.

  • Advanced control of a resistance spot welding system
    IEEE Transactions on Power Electronics, 2008
    Co-Authors: B. Klopčič, Drago Dolinar, Gorazd Stumberger
    Abstract:

    This paper deals with a middle-frequency resistance spot welding system. It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The welding current at the full-wave rectifier output is normally controlled by the pulse width modulated primary voltage of the transformer supplied by the input converter. The unequal ohmic resistances of the two transformer's secondary circuits and the different characteristics of the diodes of output rectifier certainly lead to the magnetic Saturation which, consequently, causes the unwanted spikes in the transformer's primary current and over-current protection switch-off. This disadvantage of classical spot welding systems is completely eliminated by the proposed advanced hysteresis controller (AHC), which keeps transformer iron Core Saturation within prescribed bounds regardless of how unequal the ohmic resistances and diodes' characteristics in the transformer's secondary circuits are. This is achieved by a combined closed-loop control of the welding current and closed-loop control of the iron Core Saturation level. The proposed AHC assures a very short rise time of the welding current and the best possible utilization of the transformer iron Core. © 2007 IEEE.

P. Wu - One of the best experts on this subject based on the ideXlab platform.

  • Design of a Low-Power Micromachined Fluxgate Sensor Using Localized Core Saturation Method
    IEEE Sensors Journal, 2008
    Co-Authors: P. Wu
    Abstract:

    Design of a low-power micromachined ring-type flux- gate sensor with localized Saturation Cores has been made and optimized in this work. The design is accomplished by using the electromagnetic simulation software, MagnetTM, which is capable of establishing a quantitative connection between the sensor parameters and the geometrical parameters of the model. Using recently developed data extraction techniques, the design with low power (19 mW) and high sensitivity (590 V/T at 60 muT) can be achieved after a series of simulations. For comparison, an actual device has been fabricated with sensitivity of 650 V/T at 60 muT, power consumption of 14 mW. The good agreement between the simulation and the experimental results validate our new approach for the design of low-power fluxgate. In addition, measurements using a second-harmonics-based detection circuit have been performed so that the noise, stability, and perming effect of the fabricated device are explored.

  • A Fully Integrated Ring-Type Fluxgate Sensor Based on a Localized Core Saturation Method
    IEEE Transactions on Magnetics, 2007
    Co-Authors: P. Wu
    Abstract:

    This paper reports a new micromachined fluxgate sensor with extremely low power consumption, based on a localized Core Saturation method. The extremely low power consumption is achieved by quick Saturation at the localized Core region associated with sensing coils 10 times smaller than the excitation coils. We designed and optimized the sensor by using the electromagnetic simulation software MagNet, and we compared the simulation results with the experimental results. The device exhibits a power consumption of ~14 mW, a sensitivity of 650 V/T at 60 muT, and a sensor span of ~200 muT. In comparison with previously reported micro fluxgate sensors, the newly developed sensor consumes 7 times less power, but at the expense of sensor span and linearity

  • A Fully Integrated Ring-Type Fluxgate Sensor Using A Localized Core Saturation Method
    2006 IEEE International Magnetics Conference (INTERMAG), 2006
    Co-Authors: P. Wu
    Abstract:

    This paper reports a new micromachined fluxgate sensor with extremely low power consumption using a localized Core Saturation method. The extremely low power consumption has been achieved by shrinking the magnetic Core width wound by the sensing coils, 10 times smaller than that wound by the excitation coils. With such Core configuration, the magnetic field within sensing coils will be enhanced several times larger than that within excitation coils. This will thus allow the fluxgate sensor to be operated in a localized Core Saturation mode. That is, only relatively small amount of excitation current is needed to saturate the sensing Core and induce the fluxgate effect at the sensing coils while the excitation Core is not saturated yet. The device exhibits a power consumption of ~4 mW, sensitivity of 600 V/T at 60 muT, and sensor span of ~250 muT In comparison with our previously reported micro-fluxgate sensor the newly developed sensor consumes 25 times less power but at the expense of sensor span and linearity.

  • a fully integrated ring type fluxgate sensor based on a localized Core Saturation method
    IEEE International Magnetics Conference, 2006
    Co-Authors: P. Wu
    Abstract:

    This paper reports a new micromachined fluxgate sensor with extremely low power consumption using a localized Core Saturation method. The extremely low power consumption has been achieved by shrinking the magnetic Core width wound by the sensing coils, 10 times smaller than that wound by the excitation coils. With such Core configuration, the magnetic field within sensing coils will be enhanced several times larger than that within excitation coils. This will thus allow the fluxgate sensor to be operated in a localized Core Saturation mode. That is, only relatively small amount of excitation current is needed to saturate the sensing Core and induce the fluxgate effect at the sensing coils while the excitation Core is not saturated yet. The device exhibits a power consumption of ~4 mW, sensitivity of 600 V/T at 60 muT, and sensor span of ~250 muT In comparison with our previously reported micro-fluxgate sensor the newly developed sensor consumes 25 times less power but at the expense of sensor span and linearity.

  • Design optimization of a low-power micromachined fluxgate sensor using localized Core Saturation method
    2006 12th Biennial IEEE Conference on Electromagnetic Field Computation, 2006
    Co-Authors: P. Wu
    Abstract:

    This paper presents the design optimization of a micromachined ring-type fluxgate sensor with localized Saturation Core to obtain low power consumption. The design optimization has been performed for finding a model with lowest excitation current, so the function of fluxgate can be achieved with low power consumption. The optimized model exhibits an excitation current of 100 mA, sensitivity of 540 V/T at 60 muT, and span of ~300 muT, with a power consumption of 25 mW

J. Arrillaga - One of the best experts on this subject based on the ideXlab platform.

  • HVDC converter transformer Core Saturation instability: a frequency domain analysis
    IEE Proceedings - Generation Transmission and Distribution, 1996
    Co-Authors: S. Chen, A.r. Wood, J. Arrillaga
    Abstract:

    The interaction between an HVDC converter and the Saturation characteristic of a converter transformer can lead to a type of harmonic instability widely known as converter transformer Core Saturation instability. The paper presents a linearised direct frequency domain analysis of the mechanism behind this instability. Using linearised converter transfer functions and transformer Saturation characteristics on AC and DC system equivalents, the system equations are solved to describe the phenomenon. A measure of the level of stability, Saturation stability factor, is derived and utilised to predict the system dynamics. The analysis is verified by dynamic simulation of several systems.

  • A Direct Frequency Domain Investigation of The Properties of Convertor Transformer Core Saturation Instability
    Sixth International Conference on AC and DC Power Transmission, 1996
    Co-Authors: S. Chen, A.r. Wood, J. Arrillaga
    Abstract:

    A direct frequency domain approach has been used in this paper to describe the properties of HVDC transmission systems susceptible to convertor transformer Core Saturation instability. The properties considered are the impedance profiles of AC and DC power systems, the influence of the convertor controller and the effect of different convertor steady-state operating conditions.

  • Harmonic interaction between generation and transmission systems
    IEEE Transactions on Power Delivery, 1993
    Co-Authors: A. Medina, J. Arrillaga
    Abstract:

    Simulation of the harmonic interaction between detailed models of the synchronous generator, power transformer and transmission system is achieved with the development of a unified multifrequency domain equivalent. The model incorporates detailed models of the generator harmonic conversion and magnetic Saturation, multilimb Core Saturation electrical winding connections, mutual coupling between windings and harmonic contribution of the transmission system. The results are compared with the network harmonic response using a conventional generator representation.