| 1. |
- Harnefors, Lennart, 1968, et al.
(författare)
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Input-admittance calculation and shaping for controlled voltage-source converters
- 2007
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Ingår i: IEEE Transactions on Industrial Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0046 .- 1557-9948. ; 54:6, s. 3323-3334
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Tidskriftsartikel (refereegranskat)abstract
- A controlled power electronic converter can cause local instabilities when interacting with other dynamic subsystems in a power system. Oscillations at a certain frequency cannot, however, build up if the converter differential input admittance has a positive conductance (real part) at that frequency, since power is then dissipated. In this paper, input-admittance expressions for a voltage-source converter are derived. It is seen how the admittance can be shaped in order to get a positive real part in the desired frequency regions by adjusting the controller parameters.
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| 2. |
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| 3. |
- Härsjö, Joachim, 1987, et al.
(författare)
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PERMANENT MAGNET SYNCHRONOUS GENERATOR INTER TURN FAULT IDENTIFICATION USING STATOR CURRENT ANALYSIS
- 2013
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Ingår i: 9th PhD Seminar on Wind Energy in Europe, EAWE.
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Konferensbidrag (refereegranskat)abstract
- A three phase permanent magnet synchronous generator is modeled both as a FEM model and an analytically model with an additional fourth winding that represents the faulty part of the machine. The faulty part is described as a fraction of the healthy machine. The proposed method can be used for multi pole machines as a general method for calculating the inductances is shown. Simulations show that the largest contributing parameter is the fault resistance, i.e. the contact resistance of the inter turn fault. FEM and analytical simulations show similar results but with amplitude an amplitude difference.
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| 4. |
- Wallmark, Oskar, et al.
(författare)
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Input Admittance Expressions for Field-Oriented Controlled Salient PMSM Drives
- 2012
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Ingår i: IEEE transactions on power electronics. - 0885-8993 .- 1941-0107. ; 27:3, s. 1514-1520
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents analytical expressions for the converter input admittance in field-oriented controlled permanentmagnet synchronous motor (PMSM) drives. The effect of rotorsaliency is taken into consideration and the derived admittance expressions are valid for maximum-torque-per-ampere as well ashigh-speed (field weakening) operation. Experimental results illustrate the validity of the derived admittance expressions. The presented work can be used to predict dc-link voltage instabilities inPMSM drives in, e.g., railway traction, aerospace and automotive applications.
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| 5. |
- Abasian, Alireza, et al.
(författare)
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Vacuum-Packaged Piezoelectric Energy Harvester for Powering Smart Grid Monitoring Devices
- 2019
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 66:6, s. 4447-4456
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an analytical method for the design and power optimization of vacuum-packaged piezoelectric energy harvesters. It is shown that the maximum power point of a vacuum-packaged energy harvester is different from the conventional one which occurs when the electrical damping ratio equals to its mechanical counter-part. Also, it is shown that the captured power by a vacuum-packaged energy harvester is highly sensitive to the vibration frequency due to very low-mechanical damping ratio, e.g., up to 50% power drops corresponding to 2% deviations in the frequency. The analysis and design are performed in the context of an ac-line magnetic field energy harvester in which the line frequency is also fixed and this energy harvester is useful for developing the self-powered wireless monitoring devices. Furthermore, the vacuum-packaged devices are inherently robust against dust storm and icing phenomenon, which occur for overhead power lines. The proposed analytical method is established based on simplified assumptions and then an accurate method is developed for the analysis of vacuum-packaged devices. Obtained theoretical results are verified in the laboratory through a prototype of the vacuum-packaged piezoelectric device, which captures up to 90 mu W from a 10-A line current.
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| 6. |
- Alsulami, A., et al.
(författare)
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Balancing asymmetrical load using a static var compensator
- 2015
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Ingår i: IEEE PES Innovative Smart Grid Technologies Conference Europe. ; 2015-January:January
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Konferensbidrag (refereegranskat)abstract
- Power electronic controllers are employed in the transmission and distribution levels of the power systems. In transmission level applications, Flexible AC Transmission System (FACTS) controllers, consist of shunt and series static compensators, are applied for power flow control, stability enhancement, voltage regulation and power oscillation damping. A Static Var Compensator (SVC) is a shunt-connected FACTS controller that is able to exchange reactive power with the power system in a controlled way. The SVC can be used for load balancing applications to reduce negative sequence components in the network to an acceptable level. The aim of the paper is to evaluate the dynamic performance of the SVC negative sequence controller. The benefits of the SVC negative sequence controller and characteristics is presented. The simulation illustrates that the SVC allows utilities to balance asymmetrical loads to mitigate the network negative sequence components.
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| 7. |
- Asimakopoulos, Panagiotis, 1985, et al.
(författare)
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Current Sharing inside a High Power IGBT Module at the Negative Temperature Coefficient Operating Region
- 2016
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Ingår i: 18th European Conference on Power Electronics and Applications, EPE 2016 ECCE Europe, Karlsruhe, Germany, 5-9 September 2016. - 2325-0313. - 9789075815245
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Konferensbidrag (refereegranskat)abstract
- This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.
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| 8. |
- Asimakopoulos, Panagiotis, 1985, et al.
(författare)
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Design of a Modular Multilevel Converter as an Active Front-End for a magnet supply application
- 2014
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Ingår i: 2014 16th European Conference on Power Electronics and Applications (EPE'14-ECCE Europe), Lappeenranta, Finland, 26-28 August 2014. - 2325-0313. - 9781479930159
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Konferensbidrag (refereegranskat)abstract
- The aim of this work is to describe the general design procedure of a Modular Multilevel Converter (MMC) applied as an Active Front-End (AFE) for a magnet supply for beam accelerators. The dimensioning criteria for the converter and the dc-link capacitance are presented and the grid transformer requirements are set. Considering the converter design, the arm inductance calculation is based on the specifications for the arm-current ripple and the DC-link fault tolerance, but, also, on the limitation of the second harmonic and the second-order LC resonance of the arm current. The module capacitance value is evaluated by focusing on the required switching dynamics and the capacitor-voltage ripple according to a newly proposed graphical method. The loading of each semiconductor in the half bridge is calculated via simulation, indicating the unsymmetrical current distribution. It is concluded that the current distribution for each semiconductor depends on the mode of operation of the converter. The different criteria for the choice of the number of modules per arm are discussed. Finally, the complete system, including a model for the load and the converter control strategy applied to the converter is simulated and obtained results are presented.
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| 9. |
- Asimakopoulos, Panagiotis, 1985, et al.
(författare)
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Heat sink design considerations in medium power electronic applications with long power cycles
- 2015
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Ingår i: 17th European Conference on Power Electronics and Applications, EPE-ECCE Europe 2015, Geneva, Switzerland, 8-10 September. - 9789075815221
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Konferensbidrag (refereegranskat)abstract
- The aim of this work is to investigate the impact of the heat sink thickness and material, as well as, of the convection coefficient of the water cooling system on the power-electronics module thermal stressing. The heat extraction capability of different thicknesses is tested. It is concluded that the thickest heat sink results in marginally lower temperature variation at the junction level compared to the second thickest one. In the thickest heat sink case, the linear dependence of the thermal resistance on the thickness counteracts the benefit of the increased thermal capacitance. The increase in the cooling medium flow rate, which corresponds to an increase in the convection coefficient between the heat sink bottom surface and the water, can be avoided by increasing the thickness of the heat sink. In this way, the energy consumption of the cooling system is reduced. The increase in the flow rate drastically reduces the thermal stressing in the thinnest heat sink case. The increase of the heat sink thickness can be beneficial for long power cycles. Copper and aluminum are the two materials that are compared, with the copper heat sink exhibiting a slightly increased performance. The study is conducted for a medium power DC-DC converter of a magnet supply with focus on long power cycles.
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| 10. |
- Asimakopoulos, Panagiotis, 1985, et al.
(författare)
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IGBT Power Stack Integrity Assessment Method for High-Power Magnet Supplies
- 2019
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 34:11, s. 11228-11240
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a method for assessing the integrity of a series of insulated-gate bipolar transistor (IGBT) power stacks during factory-acceptance tests and service stops. The key challenge that is addressed in this paper is detecting common assembly issues that affect the power stack thermal path as well as distinguishing the acute aging effects of bond-wire lift-off and solder delamination. The method combines offline Vce measurements with current in the extended Zero Temperature Coefficient (ZTC) operating region as well as with sensing current without modifications to the power stack. It also employs on-the-stack Vce calibration for both the measurements. Additionally, only a fixed duty cycle pattern is needed to control the switches. The paper also presents a sensitivity analysis of the method to various parameters such as the current level in the extended ZTC operating region, the precision of the Vce measurement, as well as the ambient, the cooling-water, and the junction temperatures. The experimental results are obtained from a high-current IGBT power stack used in a magnet power supply for particle accelerators and are compared favorably to results from finite element method and lumped parameter network simulations confirming the applicability of the method.
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