EPE Association: EPE 2015 - DS3j: e-Mobility: Propulsion Systems & Power Converters

EPE 2015 - DS3j: e-Mobility: Propulsion Systems & Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 08: e-Mobility > EPE 2015 - DS3j: e-Mobility: Propulsion Systems & Power Converters

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   A Direct Three-Phase to Single-Phase AC/AC Converter for Contactless Electric Vehicle Charger
By Ferdi Perdana KUSUMAH [View]
[Download]

Abstract: This paper proposes an attractive direct line-frequency three-phase to a higher frequency single-phase AC/AC converter for a contactless electric vehicle charger. It removes a DC-link capacitor of a conventional AC/AC converter but has a smaller number of bi-directional switches than a matrix converter. It operates using injection and free-oscillation modes based on a zero-current switching mechanism. Circuit descriptions including a topology, commutations and a modulation strategy are discussed using some illustrations and diagrams. An on-off control is used to simplify control of resonant current. Simulation results to study some effects due to different coupling factor and load are then presented to show converter's performance and capabilities in contactless power transfer.

   A Novel Thermal Management Algorithm for Improved Lifetime of Traction Converters
By Dennis KACZOROWSKI [View]
[Download]

Abstract: A novel active thermal management for an FOC controlled electric car is proposed, which reduces the maximum junction temperature and the load cycling stress of the traction converter by dynamic variation of switching frequency and current limit. By this means, the power losses of the converter can be decreased temporarily in high load situations, like the start-up process, to achieve lower thermal stress and so an extended lifetime. By using offline precalculations, this approach does not need to directly consider junction temperatures. Furthermore, a predictive behavior and, thus, an improved overload capability is reached. The thermal management is tested in simulations and measurements. The expected lifetime extension is determined for the New-European-Driving Cycle (NEDC) by simulation.

   A Rare-Earth Free SHEV Powertrain and its Control
By W U Nuwantha FERNANDO [View]
[Download]

Abstract: A topology of a candidate rare-earth free Series Hybrid Electric Vehicle (SHEV) powertrain and the coordinated control of its components is presented in this paper. The powertrain is fed with a field controlled synchronous generator and a controlled battery bank and drives a 60 kW rare-earth free traction motor. Simulation results are presented for normal operating conditions and two faulted-mode operating scenarios where the power electronic converter in the system is faulted are investigated.

   Automatic Selection Scheme of Most Efficient Operation Mode in Buck--boost Type Secondary-side Converter for Inductive Power Transfer
By Ryosuke OTA [View]
[Download]

Abstract: There is a case where an inductive power transfer (IPT) system is applied to battery charger for electric vehicles. A secondary-side converter, which consists of a DC-DC converter with a diode bridge rectifier, is connected to the secondary-side of the resonant circuit in order to regulate the current and voltage of a battery. Previously, the authors showed that the IPT system connected to a buck-boost type secondary-side converter is more efficient than the system connected to a buck type secondary-side converter.However, the applied buck-boost type secondary-side converter has some operation modes, which are buck mode, boost mode and buck-boost mode; and the selection scheme of the operation modes in the converter had not been considered yet. Therefore, this paper proposes an automatic mode selection scheme of the most efficient operation mode in the buck-boost type secondary-side converter for an inductive power transfer according to the input voltage and the output power variations of the converter. In addition, the effectiveness is verified by experiments and theoretical analysis. As a result, it was confirmed that the total and converter efficiencies of the IPT system with the buck-boost type secondary-side converter in the buck and boost modes were better than those of the system with the buck-boost type secondary-side converter in the buck-boost mode.

   Capacity of Power-Batteries versus Temperature
By Jan LEUCHTER [View]
[Download]

Abstract: In this paper an approach to analyses battery-capability in mobile power applications versus temperature is explored. The harmful effects of the modern material (technology) of power-batteries are to highlights. This paper considers performance of power-batteries; experimental tests-based analyses of these power-batteries are used. The performance of a Lithium-Ion, Nickel-Metal, recent Lead-Acid batteries or Supercapacitors are shown to touch on the most general features of power using in mobile applications. Two aspects of batteries are considered in this paper, battery-capability versus temperature and load-effects of high currents during the charging and discharging process. It is shown that there is an overall reduction in the internal losses due to temperature effects to take a significant reduction in battery-efficiency, so to change battery-capability. The main features of several different types of batteries are shown in this paper including their detailed analysis to show the effect of temperature change. Three possible temperatures are explored: a) -10 °C (14 F); b) 10 °C (50 F); and c) +25 °C (77 F) for low-current and a maximum-current loading to get the performance of batteries behaviors. The results shown that the value of temperature or current-loading has an effect on the capacity, because the internal resistance of batteries is variable.

   Comparison of different control strategies for series-series compensated inductive power transmission systems
By JOHANNES TRITSCHLER [View]
[Download]

Abstract: For automotive battery charging, the series-series compensated inductive power transmission shows a lot of advantages compared to other compensation techniques. As shown in many recent [1], [2] and older publications, the main advantages are the independency of the secondary current from the load at resonant frequency and the zero phase shift between primary current and voltage. As shown in [3], very high efficiencies from grid to battery of nearly 94-95\% can be reached by driving the IPT-system at constant frequency and by adapting the input and the output DC-link voltages. To achieve this control method, extra DC/DC-converters need to be added inside the power transmission path. To avoid the thereby associated higher hardware and also software effort, alternative control strategies needing fewer components are of major interest. In this paper, different control strategies and modulation schemes with and without additional DC/DC-converters are presented, theoretically evaluated with a special emphasis on partial load transmission efficiency and a selection is measured in a real system. The various control strategies were compared on one single coil geometry. The aim is to find a control method which minimizes the total system costs and maximizes the system efficiency at the same time.

   Loss modelling to optimize the overall drive train efficiency
By Martin STEMPFLE [View]
[Download]

Abstract: For drive train efficiency estimation, loss models of the battery, an optional DC/DC converter, aninverter and the electrical machine are presented. Harmonic iron losses of the machine caused bycurrent ripple ar'e considered in order to evaluate various modulation strategies and switchingfrequencies of the inverter. Battery voltage optimizations are analysed regarding the overall drive trainefficiency as well as the influence on different DC/DC converters.

   Output power increase of a series-series compensated inductive power transfer system via asymmetric loading
By Eleni GATI [View]
[Download]

Abstract: This work implements an asymmetric loading rectification technique in an Inductive Power Transfer System (IPTS) intended for use in electric vehicle wireless chargers. Asymmetric loading is performed by a half-cycle short-circuit / half-cycle loading operation, in the secondary side of a series-series compensated IPTS. The aim is to reduce the value of the load resistance as reflected to the power supply, in order to increase the power intake from a given voltage source. Increase in the power provided to the battery is of great importance in wireless charging systems, as it decreases the duration of charging. Achieving it without intervention on the input voltage source is an additional advantage, since it decreases the number of converters used for the system. Simulations and experiments are carried out in a series-series compensated prototype IPTS for a variety of resistive loads. Results show a significant increase in the output power, especially for high resistance loads, in comparison with the conventional full wave rectification. Equivalent results are obtained by charging a 28.8 V, 20 Ah LiFePO4 battery pack.

   PWM Modulation for a Three-Level Inverter with Neutral-Point Balancing for a Permanent Magnet Synchronous Machine
By Stephan BRUESKE [View]
[Download]

Abstract: A neutral point (NP) balancing modulation for a three-level inverter with cos_ > 0.9 is presented. In thelow modulation range, standard space vector modulation (SVM) is applied using the redundancy of thesmall space vectors (SV) for the NP balancing. In the high modulation range, the switching sequence isadapted so that the neutral-point voltage can be also balanced. The proposed method is compared withthe modulation concept of the virtual SV concept. Experimental validation of the modulation scheme ispresented.

   Three Phase Voltage Source Inverter Using SiC MOSFETs; Design and Optimization
By Hani MUHSEN [View]
[Download]

Abstract: This work aims at designing a three-phase voltage source inverter using SiC MOSFET, which is dedicated to electric vehicle applications. Power losses of the SiC MOSFET will be analyzed, and general guidelines for a minimum heat-sink size selection based on the static thermal behavior will be addressed. Furthermore, EMI parasitic parameters resulting from the traces' inductances and the heat-sink will be estimated based on the physical behavior and the layout of the power circuit without the requirements of commercial software tools. The estimated EMI behavior of the voltage source inverter will be compared with the experimental results within the conducted EMI range in order to validate the analysis.

   Ultra-Fast Charging Station for Electric Vehicles with integrated split Grid Storage
By Daniel CHRISTEN [View]
[Download]

Abstract: This paper presents the detailed analysis, optimisation and hardware realisation of an ultra-fast charging station with a split grid storage battery which enables to recharge electric vehicles (EVs) in less than 10 minutes. The station consists of a T-type AC-DC grid interface connected to the 400 V low voltage AC grid, a DC-DC dual active bridge (DAB) isolation stage, a stationary storage battery and a high power multi-phase interleaved buck converter for charging operation. The operating principle of the converter systems is briefly explained and the analytical loss models of the components are derived which are used in an optimisation procedure to evaluate the pareto front limits in terms of efficiency and power density for the DAB isolation stage and the high power charger. By introducing a split storage battery, beneficial conditions for the semiconductor devices are achieved so that the losses of the high power charger can be reduced by approximately 35 \% with respect to a standard solution without a split as will be shown in the paper.

EPE 2015 - DS3j: e-Mobility: Propulsion Systems & Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 08: e-Mobility > EPE 2015 - DS3j: e-Mobility: Propulsion Systems & Power Converters
	[return to parent folder]

	A Direct Three-Phase to Single-Phase AC/AC Converter for Contactless Electric Vehicle Charger By Ferdi Perdana KUSUMAH	[View] [Download]
Abstract: This paper proposes an attractive direct line-frequency three-phase to a higher frequency single-phase AC/AC converter for a contactless electric vehicle charger. It removes a DC-link capacitor of a conventional AC/AC converter but has a smaller number of bi-directional switches than a matrix converter. It operates using injection and free-oscillation modes based on a zero-current switching mechanism. Circuit descriptions including a topology, commutations and a modulation strategy are discussed using some illustrations and diagrams. An on-off control is used to simplify control of resonant current. Simulation results to study some effects due to different coupling factor and load are then presented to show converter's performance and capabilities in contactless power transfer.

	A Novel Thermal Management Algorithm for Improved Lifetime of Traction Converters By Dennis KACZOROWSKI	[View] [Download]
Abstract: A novel active thermal management for an FOC controlled electric car is proposed, which reduces the maximum junction temperature and the load cycling stress of the traction converter by dynamic variation of switching frequency and current limit. By this means, the power losses of the converter can be decreased temporarily in high load situations, like the start-up process, to achieve lower thermal stress and so an extended lifetime. By using offline precalculations, this approach does not need to directly consider junction temperatures. Furthermore, a predictive behavior and, thus, an improved overload capability is reached. The thermal management is tested in simulations and measurements. The expected lifetime extension is determined for the New-European-Driving Cycle (NEDC) by simulation.

	A Rare-Earth Free SHEV Powertrain and its Control By W U Nuwantha FERNANDO	[View] [Download]
Abstract: A topology of a candidate rare-earth free Series Hybrid Electric Vehicle (SHEV) powertrain and the coordinated control of its components is presented in this paper. The powertrain is fed with a field controlled synchronous generator and a controlled battery bank and drives a 60 kW rare-earth free traction motor. Simulation results are presented for normal operating conditions and two faulted-mode operating scenarios where the power electronic converter in the system is faulted are investigated.

	Automatic Selection Scheme of Most Efficient Operation Mode in Buck--boost Type Secondary-side Converter for Inductive Power Transfer By Ryosuke OTA	[View] [Download]
Abstract: There is a case where an inductive power transfer (IPT) system is applied to battery charger for electric vehicles. A secondary-side converter, which consists of a DC-DC converter with a diode bridge rectifier, is connected to the secondary-side of the resonant circuit in order to regulate the current and voltage of a battery. Previously, the authors showed that the IPT system connected to a buck-boost type secondary-side converter is more efficient than the system connected to a buck type secondary-side converter.However, the applied buck-boost type secondary-side converter has some operation modes, which are buck mode, boost mode and buck-boost mode; and the selection scheme of the operation modes in the converter had not been considered yet. Therefore, this paper proposes an automatic mode selection scheme of the most efficient operation mode in the buck-boost type secondary-side converter for an inductive power transfer according to the input voltage and the output power variations of the converter. In addition, the effectiveness is verified by experiments and theoretical analysis. As a result, it was confirmed that the total and converter efficiencies of the IPT system with the buck-boost type secondary-side converter in the buck and boost modes were better than those of the system with the buck-boost type secondary-side converter in the buck-boost mode.

	Capacity of Power-Batteries versus Temperature By Jan LEUCHTER	[View] [Download]
Abstract: In this paper an approach to analyses battery-capability in mobile power applications versus temperature is explored. The harmful effects of the modern material (technology) of power-batteries are to highlights. This paper considers performance of power-batteries; experimental tests-based analyses of these power-batteries are used. The performance of a Lithium-Ion, Nickel-Metal, recent Lead-Acid batteries or Supercapacitors are shown to touch on the most general features of power using in mobile applications. Two aspects of batteries are considered in this paper, battery-capability versus temperature and load-effects of high currents during the charging and discharging process. It is shown that there is an overall reduction in the internal losses due to temperature effects to take a significant reduction in battery-efficiency, so to change battery-capability. The main features of several different types of batteries are shown in this paper including their detailed analysis to show the effect of temperature change. Three possible temperatures are explored: a) -10 °C (14 F); b) 10 °C (50 F); and c) +25 °C (77 F) for low-current and a maximum-current loading to get the performance of batteries behaviors. The results shown that the value of temperature or current-loading has an effect on the capacity, because the internal resistance of batteries is variable.

	Comparison of different control strategies for series-series compensated inductive power transmission systems By JOHANNES TRITSCHLER	[View] [Download]
Abstract: For automotive battery charging, the series-series compensated inductive power transmission shows a lot of advantages compared to other compensation techniques. As shown in many recent [1], [2] and older publications, the main advantages are the independency of the secondary current from the load at resonant frequency and the zero phase shift between primary current and voltage. As shown in [3], very high efficiencies from grid to battery of nearly 94-95\% can be reached by driving the IPT-system at constant frequency and by adapting the input and the output DC-link voltages. To achieve this control method, extra DC/DC-converters need to be added inside the power transmission path. To avoid the thereby associated higher hardware and also software effort, alternative control strategies needing fewer components are of major interest. In this paper, different control strategies and modulation schemes with and without additional DC/DC-converters are presented, theoretically evaluated with a special emphasis on partial load transmission efficiency and a selection is measured in a real system. The various control strategies were compared on one single coil geometry. The aim is to find a control method which minimizes the total system costs and maximizes the system efficiency at the same time.

	Loss modelling to optimize the overall drive train efficiency By Martin STEMPFLE	[View] [Download]
Abstract: For drive train efficiency estimation, loss models of the battery, an optional DC/DC converter, aninverter and the electrical machine are presented. Harmonic iron losses of the machine caused bycurrent ripple ar'e considered in order to evaluate various modulation strategies and switchingfrequencies of the inverter. Battery voltage optimizations are analysed regarding the overall drive trainefficiency as well as the influence on different DC/DC converters.

	Output power increase of a series-series compensated inductive power transfer system via asymmetric loading By Eleni GATI	[View] [Download]
Abstract: This work implements an asymmetric loading rectification technique in an Inductive Power Transfer System (IPTS) intended for use in electric vehicle wireless chargers. Asymmetric loading is performed by a half-cycle short-circuit / half-cycle loading operation, in the secondary side of a series-series compensated IPTS. The aim is to reduce the value of the load resistance as reflected to the power supply, in order to increase the power intake from a given voltage source. Increase in the power provided to the battery is of great importance in wireless charging systems, as it decreases the duration of charging. Achieving it without intervention on the input voltage source is an additional advantage, since it decreases the number of converters used for the system. Simulations and experiments are carried out in a series-series compensated prototype IPTS for a variety of resistive loads. Results show a significant increase in the output power, especially for high resistance loads, in comparison with the conventional full wave rectification. Equivalent results are obtained by charging a 28.8 V, 20 Ah LiFePO4 battery pack.

	PWM Modulation for a Three-Level Inverter with Neutral-Point Balancing for a Permanent Magnet Synchronous Machine By Stephan BRUESKE	[View] [Download]
Abstract: A neutral point (NP) balancing modulation for a three-level inverter with cos_ > 0.9 is presented. In thelow modulation range, standard space vector modulation (SVM) is applied using the redundancy of thesmall space vectors (SV) for the NP balancing. In the high modulation range, the switching sequence isadapted so that the neutral-point voltage can be also balanced. The proposed method is compared withthe modulation concept of the virtual SV concept. Experimental validation of the modulation scheme ispresented.

	Three Phase Voltage Source Inverter Using SiC MOSFETs; Design and Optimization By Hani MUHSEN	[View] [Download]
Abstract: This work aims at designing a three-phase voltage source inverter using SiC MOSFET, which is dedicated to electric vehicle applications. Power losses of the SiC MOSFET will be analyzed, and general guidelines for a minimum heat-sink size selection based on the static thermal behavior will be addressed. Furthermore, EMI parasitic parameters resulting from the traces' inductances and the heat-sink will be estimated based on the physical behavior and the layout of the power circuit without the requirements of commercial software tools. The estimated EMI behavior of the voltage source inverter will be compared with the experimental results within the conducted EMI range in order to validate the analysis.

	Ultra-Fast Charging Station for Electric Vehicles with integrated split Grid Storage By Daniel CHRISTEN	[View] [Download]
Abstract: This paper presents the detailed analysis, optimisation and hardware realisation of an ultra-fast charging station with a split grid storage battery which enables to recharge electric vehicles (EVs) in less than 10 minutes. The station consists of a T-type AC-DC grid interface connected to the 400 V low voltage AC grid, a DC-DC dual active bridge (DAB) isolation stage, a stationary storage battery and a high power multi-phase interleaved buck converter for charging operation. The operating principle of the converter systems is briefly explained and the analytical loss models of the components are derived which are used in an optimisation procedure to evaluate the pareto front limits in terms of efficiency and power density for the DAB isolation stage and the high power charger. By introducing a split storage battery, beneficial conditions for the semiconductor devices are achieved so that the losses of the high power charger can be reduced by approximately 35 \% with respect to a standard solution without a split as will be shown in the paper.