EPE Association: EPE 2021 - Converter Design and Optimisation

EPE 2021 - Converter Design and Optimisation
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2021 ECCE Europe - Conference > EPE 2021 - Topic 03: Measurement and Control > EPE 2021 - Converter Design and Optimisation

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   An Analytic Inverter Loss Model for Design and Operation Space Optimization
By Lukas FRÄGER [View]
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Abstract: This paper presents an analytic loss model for fast switching inverters including filter losses. A new modelling approach with the focus on calculation performance is presented. An accurate inductor loss model as well as a new semiconductor loss model, that considers soft transition, are presented. The modelling approach is validated based on a 10 kVA three-phase voltage source inverter, showing a precise and efficient method for optimization algorithms.

   Efficiency and Power Density Evaluations of Bidirectional Non-isolated DC-DC converter Based on Flying-capacitor Converters
By Kazuaki TESAKI [View]
[Download]

Abstract: This study carries out the efficiency and power density evaluations of a bidirectional non-isolated dc-dc converter based on flying-capacitor converters using Pareto optimization method. The converter comprises a main converter with four power devices and an auxiliary converter, each of which is formed by cascaded chopper cells. A converter design procedure based on Pareto optimization method is proposed, followed by the discussions how the carrier frequencies of the main and auxiliary converters, and the chopper-cell count affect the efficiency and power density of the converter. Consequently, it is revealed that the maximum power density can be achieved when using four cells in the auxiliary converter. The validity and effectiveness of the design method presented in this paper are verified using a 200-V, 1-kW down-scaled model. Further, the efficiency and power density evaluations of an actual dc-dc converter system rated at 100 kW are carried out using numerical analysis based on the MATLAB software package.

   Reduction of the Turn-Off Overvoltage in an Active Full-Bridge Rectifier Stage by Paralleling GaN-HEMTs
By Tino KAHL [View]
[Download]

Abstract: A GaN half-bridge, suffering from high turn-off overvoltage preventing further load current increase, is improved by paralleling GaN-HEMTs (Gallium Nitride - High Electron Mobility Transistor). To compare both designs, a method combining 3D-FEM and SPICE simulations is presented and validated by measurements of the initial half-bridge's switching characteristic. This method is then applied to the half-bridge with parallel HEMTs. The simulation of commutation paths in the parallel connection verifies the layout's symmetry, proven by measuring the switching behaviour using these paths. Switching tests of the entire parallel half-bridge demonstrate the successful reduction of the overvoltage peak for the application's desired load current. They further show a basically even load current distribution, with an almost identical slew-rate of the current transients rebalancing after an unbalanced time. From the analysis of this time, it is concluded that its reason should be an effect on the gate-source behaviour with a relatively long time constant, not only explainable by static threshold voltage (Vth) differences between the parallel transistors. By manipulating the static Vth difference in the SPICE simulation to a higher value than measured the current distribution can be described including the unbalanced behaviour.

   Reliability and Cost Assessment of Fault-Tolerant Inverter Topologies for Multi- Motor Drive Systems
By Mustapha AL SAKKA [View]
[Download]

Abstract: Automotive x-by-wire (XBW) systems require the development of cost-effective, compact, and reliable motor drive solutions. With the multiport inverter architecture, it is possible to improve on these aspects. In this paper inverter fault tolerance strategies are first reviewed, and proper ones are selected. The strategies are then applied to single-input multi-output (SIMO) inverter topologies and 2, 3 and 4 motor systems are considered. Next, the cost and reliability of the resulting topologies are assessed and compared. Finally, the suitability of these topologies considering automotive applications requirements is discussed. It was found that the leg redundant strategy is the most suitable one and that the cost and reliability are both improved when that strategy is applied to SIMO topologies. The improvements are also more significant for a higher number of motors. The conventional combined topology was found to be the best for general XBW systems but in special applications the shared-leg topology can be a better solution.

EPE 2021 - Converter Design and Optimisation
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2021 ECCE Europe - Conference > EPE 2021 - Topic 03: Measurement and Control > EPE 2021 - Converter Design and Optimisation
	[return to parent folder]

	An Analytic Inverter Loss Model for Design and Operation Space Optimization By Lukas FRÄGER	[View] [Download]
Abstract: This paper presents an analytic loss model for fast switching inverters including filter losses. A new modelling approach with the focus on calculation performance is presented. An accurate inductor loss model as well as a new semiconductor loss model, that considers soft transition, are presented. The modelling approach is validated based on a 10 kVA three-phase voltage source inverter, showing a precise and efficient method for optimization algorithms.

	Efficiency and Power Density Evaluations of Bidirectional Non-isolated DC-DC converter Based on Flying-capacitor Converters By Kazuaki TESAKI	[View] [Download]
Abstract: This study carries out the efficiency and power density evaluations of a bidirectional non-isolated dc-dc converter based on flying-capacitor converters using Pareto optimization method. The converter comprises a main converter with four power devices and an auxiliary converter, each of which is formed by cascaded chopper cells. A converter design procedure based on Pareto optimization method is proposed, followed by the discussions how the carrier frequencies of the main and auxiliary converters, and the chopper-cell count affect the efficiency and power density of the converter. Consequently, it is revealed that the maximum power density can be achieved when using four cells in the auxiliary converter. The validity and effectiveness of the design method presented in this paper are verified using a 200-V, 1-kW down-scaled model. Further, the efficiency and power density evaluations of an actual dc-dc converter system rated at 100 kW are carried out using numerical analysis based on the MATLAB software package.

	Reduction of the Turn-Off Overvoltage in an Active Full-Bridge Rectifier Stage by Paralleling GaN-HEMTs By Tino KAHL	[View] [Download]
Abstract: A GaN half-bridge, suffering from high turn-off overvoltage preventing further load current increase, is improved by paralleling GaN-HEMTs (Gallium Nitride - High Electron Mobility Transistor). To compare both designs, a method combining 3D-FEM and SPICE simulations is presented and validated by measurements of the initial half-bridge's switching characteristic. This method is then applied to the half-bridge with parallel HEMTs. The simulation of commutation paths in the parallel connection verifies the layout's symmetry, proven by measuring the switching behaviour using these paths. Switching tests of the entire parallel half-bridge demonstrate the successful reduction of the overvoltage peak for the application's desired load current. They further show a basically even load current distribution, with an almost identical slew-rate of the current transients rebalancing after an unbalanced time. From the analysis of this time, it is concluded that its reason should be an effect on the gate-source behaviour with a relatively long time constant, not only explainable by static threshold voltage (Vth) differences between the parallel transistors. By manipulating the static Vth difference in the SPICE simulation to a higher value than measured the current distribution can be described including the unbalanced behaviour.

	Reliability and Cost Assessment of Fault-Tolerant Inverter Topologies for Multi- Motor Drive Systems By Mustapha AL SAKKA	[View] [Download]
Abstract: Automotive x-by-wire (XBW) systems require the development of cost-effective, compact, and reliable motor drive solutions. With the multiport inverter architecture, it is possible to improve on these aspects. In this paper inverter fault tolerance strategies are first reviewed, and proper ones are selected. The strategies are then applied to single-input multi-output (SIMO) inverter topologies and 2, 3 and 4 motor systems are considered. Next, the cost and reliability of the resulting topologies are assessed and compared. Finally, the suitability of these topologies considering automotive applications requirements is discussed. It was found that the leg redundant strategy is the most suitable one and that the cost and reliability are both improved when that strategy is applied to SIMO topologies. The improvements are also more significant for a higher number of motors. The conventional combined topology was found to be the best for general XBW systems but in special applications the shared-leg topology can be a better solution.