EPE Association: EPE 2009 - Subtopic 02-3 - DS: 'Passive Components, System Integration & Packaging'

EPE 2009 - Subtopic 02-3 - DS: 'Passive Components, System Integration & Packaging'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 02: 'Passive Components, System Integration and Packaging' > EPE 2009 - Subtopic 02-3 - DS: 'Passive Components, System Integration & Packaging'

   [return to parent folder]

   A NEW INTERCELL TRANSFORMER FOR INTERLEAVED CONVERTERS
By Bernardo COUGO, Valentin COSTAN, Thierry MEYNARD, FranÃ§ois FOREST, Eric LABOURE [View]
[Download]

Abstract: This paper describes a new topology of interleaved power converters using intercell transformers. A modified sequence of the voltages applied to windings is used to reduce the flux density in the magnetic core branches, consequently reducing core losses and the risk of saturating the magnetic material. Since the power density of the converter is high, a new assembling technique to construct the intercell transformers is used to allow easy cooling of the magnetic core branches which have higher magnetic flux. Experimental measurements confirm the topology operation and the flux reduction obtained with the modified supply.

   Acoustic Noise of Sheeted Electrical Steel Inductors in PWM Operation â€“ Causes and Mitigation
By Stefan SCHMITT, Kai WANG, Stefan BEYER [View]
[Download]

Abstract: Electrical steel inductors are superior in size and cost compared to inductors using alternative core like nanocrystalline or powder materials in applications involving pulse-width modulated currents. However, electrical steel tends to emit more acoustic noise, which can be undesirable. The causes for these acoustic noise emissions, i.e. magnetic forces and magnetostriction, are explained in detail and the particular flux density distribution in sheeted electrical steel inductors at PWM operating is derived. Based on these insights, two methods of reducing the noise of an electrical steel inductor are proposed. One method implies a redesign of the inductor for lower nominal flux density. The other method is based on changing only the mechanical construction of the inductor. It does not affect the main design parameters of an inductor, i.e. inductance and temperature rise, and can thus be applied to existing inductor designs.

   Application of heat pipe based refrigeration system for an electric train traction converter. An experimental study case
By Aritz ARRIZABALAGA, Joseba MURUA, Pedro ESTEVEZ, Igor ALONSO, Iosu IBARBIA, Txomin NIEVA [View]
[Download]

Abstract: Refrigeration systems of railway traction inverters have experienced crucial progress recently. The use of assisted convection has been one of the most significant improvements, being heat pipe based heat sinks (HPHS) the main application. Due to the operating principle of a heat pipe, which lies in evaporation and condensation of a fluid, the HPHS is a very non-linear device. Several variables play a critical role and a simple theoretical analysis by itself does not provide enough information for an accurate model. As a result, in order to evaluate the performance of a HPHS for a generic traction converter, we have developed an experimentation process. It consists of aerodynamic tests in an airport and thermal tests in a self-designed wind tunnel. The objective of this method is the complete characterisation of the HPHS and thereby, the prediction of the behaviour of the refrigeration system for the real operation of a train. During the aerodynamic tests we have deduced the relationship between the air-flow through the HPHS and the train speed. Besides, we have analysed some extra phenomena, such as the double-cavity flow and the air-leakage of the system. The thermal study has allowed us to determine the thermal resistance network, working out the influence of the power losses of the inverter and the air velocity in the overall efficiency of the HPHS. In addition, we have examined transient response and the importance of natural convection. The paper summarizes both series of tests carried out with the system subject to study and presents the main results and conclusions.

   Comparison of Fields Emitted from High Frequency Silicon-Integrated, Microfabricated Inductors
By Michal LAZARCZYK, Terence O'DONNELL, Noel BARRY, Ronan MEERE [View]
[Download]

Abstract: Technological progress and development is bringing commercially available power supplies integrated in a single chip closer and closer to reality. One of crucial milestones in this process is integration of inductors with magnetic core onto a silicon substrate. Such inductors enable full integration of a switch mode voltage converter in a single chip, provided that the switching frequency is high enough. This significant increase of switching frequency creates new problems for IC designers and engineers, especially related to electromagnetic interferences and compatibility. This paper presents simulated electromagnetic fields emitted by two commonly used designs of magnetic core inductors and an air core coil of corresponding inductance. Comparison of emitted fields is based on simulation results obtained with Ansoft Maxwell 3D. The aim of the work is to determine levels of radiation in silicon die and above it in order to identify problems that may rise in IC design, as well as exploring the feasible advantages and drawbacks of possible shielding.

   Design of the Fixed Frequency Controlled Piezoelectric Transformer based DC/DC converter
By Yuan-Ping LIU, Dejan VASIC, FranÃ§ois COSTA, Wen-Jong WU, Chih-Kung LEE [View]
[Download]

Abstract: Piezoelectric transformers (PT) converters show some difficulties to work in the case of the variable load at fixed frequency. PTs can be designed to achieve these problems, but the size of the PT may become larger. In fact, the selection of the circuit topologies and the control methods influence the size and the efficiency of the PT converter. Two rectifiers (half-wave rectifier and the full-wave rectifier) were compared and two control methods (PWM control and burst mode control) were compared according to the efficiency of the converter. The full-wave rectifier and the burst-mode hysteresis control are the better choice. The hysteresis control was also proposed to improve the dynamic response of the burst-mode control.

   Direct Substrate Cooling of Power Electronics
By Robert SKURIAT, Mark JOHNSON [View]
[Download]

Abstract: Liquid jet impingement can be used to efficiently generate high heat transfer coefficients for cooling. However, optimization of the jet impingement array is complicated as a large number of geometrical parameters, such as array size, jet spacing and jet diameter affect performance. In the studies described in this paper a custom designed half-bridge substrate tile, supporting two IGBT and two diode dies, is cooled using liquid jet impingement onto the underside of the active metal brazed (AMB) Aluminium Nitride substrate tile. In order to reduce redundancy in the cooling system, the impingement array is designed to directly target the hot spots on the underside of the tile. A number of jet impingement arrays are designed and compared in order to determine which impingement geometry provides the most effective cooling. The performance of each cooling array is presented as a function of temperature rise of the IGBT dies with fluid flow rate, pressure drop across the cooler and pumping power required. A 6 x 6 array of 0.5mm diameter jets spaced at 2mm is found to be the most efficient. At a pumping power requirement of 5 W the jet impingement cooler is able to maintain the IGBT dies at a temperature 22.38Â°C above the water temperature while dissipating 400 W of heat. Further experimental work is discussed.

   Domestic Induction Heating Impedance Modeling Including Windings, Load, and Ferrite Substrate
By Jesus ACERO, Rafael ALONSO, Luis Angel BARRAGAN, Claudio CARRETERO, Oscar LUCIA, Ignacio MILLAN, Jose Miguel BURDIO [View]
[Download]

Abstract: Integral expressions of the equivalent impedance of flat-type coils for induction heating systems are derived. These expressions are obtained by integration the analytical solution of the field generated by a circular filamentary current placed between two linear and homogeneous semi-infinite media. It is considered that the windings are wound with a round wire. The model also gives the magnetic field in the cross section of the windings, which is necessary to calculate the proximity losses in the cables. The solution is given in terms of Bessel function integrals, which are calculated by means of MATLAB. Several prototypes having different turns were constructed and tested with different loads. Measurements confirm the validity of the analytical models.

   Dynamic Junction Temperature Calculation and Measurement by Four-Pole Theory and Complex Fourier Series
By Thomas KOMMA, Walter KIFFE [View]
[Download]

Abstract: The development of power supply technology has always been associated with the need for further miniaturization. This means that power semiconductors must be mounted at short distances on the same heat sink. Adjacent power semiconductors have an increasing influence on the chip temperature. The maximum junction temperatures, which are specified by the manufacturer under all operating conditions, may not be exceeded. As a rule, the chip temperatures are calculated on the basis of the losses and thermal impedance of a power semiconductor according to manufacturerâ€™s specifications. The following paper presents a procedure for determining the junction temperatures of power semiconductors in switch-mode power supplies, considering common heat-sink and arbitrary power-loss functions.

   Experimental Characterisation and Modelling of High-Voltage IGBT Modules Off-State Thermal Instability
By Alberto CASTELLAZZI, Jose SAIZ, Michel MERMET-GUYENNET [View]
[Download]

Abstract: This paper proposes the experimental characterization and modeling of thermal runaway phenomena affecting high-voltage devices in the blocking state. In particular, it considers 6.5 kV rated multi-chip IGBT modules, of the kind employed in railway traction applications, showing how temperature and reverse bias voltage influence the off-state power losses and how the same thermal design may yield thermal instability for devices of different manufacturers. Additionally, evidence is shown of significant temperature mismatches for the chips within a module, which enhance the risk of failure. In order to analyze all of these effects, an advanced modeling technique is applied, which couples analytical models of semiconductor physics with a 3D numerical model of thermal effects. This allows for an in-depth, still handy analysis, useful for optimized and reliable thermal design.

   Fabrication of bottom die substrate solderless interconnection based on nano copper wires
By Van-Hai NGUYEN [View]
[Download]

Abstract: Direct Copper Bonded (DBC) bottom die substrate attachment is usually ensured by solder joints but with regard to reliability it remains the weakest component of the package. The sustained trend for high power density requires new interconnection technologies. Nano-wires seem to be a promising candidate for interconnection applications in power electronics and microelectronics [1-5]. This paper presents the fabrication process of an innovative solderless interconnection based on copper nano-wires by electroplating process, itself using the Anodic Aluminum Oxide (AAO) template. Some mechanical and electrical characterizations are investigated in order to evaluate this interconnection technology.

   Loss eveluation of ac filter inductor core on a PWM Inverter
By Toshihisa SHIMIZU [View]
[Download]

Abstract: Iron loss of an AC filter inductor used in a PWM inverter is discussed based on a dynamic minor loop method developed by the authors. A distinctive feature of the dynamic minor loop method is that the instantaneous iron loss of the AC filter inductor can be measured during every switching period of the inverter, and the instantaneous iron loss distribution during one cycle of the output frequency cycle can be produced using this data. The shape of the distribution changes with both the modulation method of the inverter and the load conditions, so that this method is suitable for characterization of the iron loss. Iron loss of the AC filter inductor can be categorized as two types; one type is high frequency loss, which is caused by the switching ripple current, and the other is low frequency loss caused by the low frequency output current. High frequency loss is usually much higher than low frequency loss; therefore, mainly the high frequency loss was evaluated in this study. The instantaneous iron loss of an AC filter inductor and the total loss under various conditions of the PWM inverter are measured, and the relationships between the output current and the iron loss, the DC-bus voltage and the iron loss, and the power factor and the iron loss are discussed.

   Multiobjective Optimal Design of High Frequency Transformers Using Genetic Algorithms
By Christophe VERSELE, Olivier DEBLECKER, Jacques LOBRY [View]
[Download]

Abstract: This paper deals with the multiobjective optimization design of high frequency transformers using genetic algorithms. In its most general form, the design problem requires minimizing the mass or overall dimensions of the core and windings as well as the loss of the transformer while ensuring the satisfaction of a number of constraints. In this contribution, the area product (i.e. the product of the core cross section and the winding area) and the power loss are used as objective functions whereas the operating frequency and the maximum flux density are chosen as optimization variables. The constraints include, as for them, appropriate limits on efficiency, maximum surface temperature rise and maximum ratio no-load/full load current. The area product is optimized in place of weight or volume of the transformer because these two quantities can be easily expressed in terms of area product. It is an elegant mean to limit the number of objective functions. The major advantage of the suggested design procedure is that it proposes to the designer a set of optimal transformers â€“ instead of a single solution â€“ so he can choose a posteriori which of them best fits the application under consideration. Finally, in order to illustrate the design procedure, the optimal design of a transformer supplied with square voltage waveform is performed and the results are discussed.

   New power electronics components concept for automated manufacturing
By Ivan JOSIFOVIC, Jelena POPOVIC, Braham FERREIRA [View]
[Download]

Abstract: This paper introduces a new concept for surface mount technology (SMT) automated manufacturing of power converters â€“ PCB Power Sandwich. The Power Sandwich manufacturing method employs new x-dimension (x-dim) components, having the same height (x) and double sided SMT electrical terminations. The components are stacked between planar substrates and soldered on both, top and bottom sides using the multilayer Power Sandwich assembly process. By arranging the components in different stack layers an increase in power density, better heat removal and improved EMI performance of power converters can be achieved. New x-dim components enable fully SMT automated power converters manufacturing with short production time and low assembly cost.

   Over-current turn-off failure in high voltage IGBT modules under clamped inductive load
By Xavier PERPINYA, Jesus URRESTI-IBAÃ‘EZ, Jean-FranÃ§ois SERVIERE, Xavier JORDA, Salvador HIDALGO, JosÃ© REBOLLO, Michel MERMET-GUYENNET [View]
[Download]

Abstract: Considering typical conditions of railway traction applications, this paper presents an experimental and simulative analysis of over-current turn-off failure in IGBT devices packaged in parallel within IGBT multichip modules. Extensive experimental analysis is carried out by means of a dedicated test-circuit. Thus, for greater insight, electro-thermal simulations at device level have been carried out. The results show that mismatches in the electro-thermal properties of the IGBT device during transient operation can lead to uneven power dissipation, significantly enhancing the risk of failure.

   Real-Time Comparison of Power Module Failure Modes under In-service Conditions
By Mahera MUSALLAM, Mark JOHNSON, Chunyan YIN , Chris BAILEY [View]
[Download]

Abstract: In order to meet the through-life reliability targets for power modules, it is critical to understand the response of typical wear-out mechanisms, for example wire-bond lifting and solder degradation, to in-service environmental and load-induced thermal cycling. Application of accurate wear-out models can identify the dominant failure mechanisms at the design stage and can be employed in reliability assessment and health management under in-service conditions. The work in this paper presents the effect of power cycling frequency, load current and mean temperature on temperature variations within the power module structure and its impact on the life consumption for two common wear-out mechanisms (the bond wire and the substrate-solder). Compact real-time thermal models combined with physics of failure based reliability analysis are used to identify the dominant failure mechanism and predict the life-time of the power module for each thermal cycling condition. It is shown that bond wire degradation is the dominant failure mechanism for all power cycling conditions whereas substrate solder failure dominates for externally applied (ambient or passive) thermal cycling. In addition to informing the design process and enabling real-time health management, the knowledge gained from these studies can be used to design thermal cycling experiments for selected failure mechanisms.

   Requirements on the Power Cycling Capability of IGBT modules in Traction Applications
By Andreas NAGEL, Fabian QUAST [View]
[Download]

Abstract: Modern railway traction converters are equipped with IGBT-modules. Due to the mode of operation and a service lifetime of 30 years, typically specified for traction applications, the cycling capability is an important issue in converter design. The requirements from the application are summarized and design targets for the next generation of IGBT modules are discussed in this paper.

   Voltage and Current Ripple Considerations for Improving Lifetime of Supercapacitors Used for Energy Buffer Applications at Converter Inputs
By Supratim BASU, TORE UNDELAND [View]
[Download]

Abstract: While supercapacitors offer high power density, high cycling capability and mechanical robustness, voltage and current ripple from downstream PWM converters can result in their overcharging or heating resulting in their lifetime reduction. This paper discusses how a simple novel design scheme of using a very low value series inductance significantly increases capacitor lifetime.

EPE 2009 - Subtopic 02-3 - DS: 'Passive Components, System Integration & Packaging'
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2009 - Conference > EPE 2009 - Topic 02: 'Passive Components, System Integration and Packaging' > EPE 2009 - Subtopic 02-3 - DS: 'Passive Components, System Integration & Packaging'
	[return to parent folder]

	A NEW INTERCELL TRANSFORMER FOR INTERLEAVED CONVERTERS By Bernardo COUGO, Valentin COSTAN, Thierry MEYNARD, FranÃ§ois FOREST, Eric LABOURE	[View] [Download]
Abstract: This paper describes a new topology of interleaved power converters using intercell transformers. A modified sequence of the voltages applied to windings is used to reduce the flux density in the magnetic core branches, consequently reducing core losses and the risk of saturating the magnetic material. Since the power density of the converter is high, a new assembling technique to construct the intercell transformers is used to allow easy cooling of the magnetic core branches which have higher magnetic flux. Experimental measurements confirm the topology operation and the flux reduction obtained with the modified supply.

	Acoustic Noise of Sheeted Electrical Steel Inductors in PWM Operation â€“ Causes and Mitigation By Stefan SCHMITT, Kai WANG, Stefan BEYER	[View] [Download]
Abstract: Electrical steel inductors are superior in size and cost compared to inductors using alternative core like nanocrystalline or powder materials in applications involving pulse-width modulated currents. However, electrical steel tends to emit more acoustic noise, which can be undesirable. The causes for these acoustic noise emissions, i.e. magnetic forces and magnetostriction, are explained in detail and the particular flux density distribution in sheeted electrical steel inductors at PWM operating is derived. Based on these insights, two methods of reducing the noise of an electrical steel inductor are proposed. One method implies a redesign of the inductor for lower nominal flux density. The other method is based on changing only the mechanical construction of the inductor. It does not affect the main design parameters of an inductor, i.e. inductance and temperature rise, and can thus be applied to existing inductor designs.

	Application of heat pipe based refrigeration system for an electric train traction converter. An experimental study case By Aritz ARRIZABALAGA, Joseba MURUA, Pedro ESTEVEZ, Igor ALONSO, Iosu IBARBIA, Txomin NIEVA	[View] [Download]
Abstract: Refrigeration systems of railway traction inverters have experienced crucial progress recently. The use of assisted convection has been one of the most significant improvements, being heat pipe based heat sinks (HPHS) the main application. Due to the operating principle of a heat pipe, which lies in evaporation and condensation of a fluid, the HPHS is a very non-linear device. Several variables play a critical role and a simple theoretical analysis by itself does not provide enough information for an accurate model. As a result, in order to evaluate the performance of a HPHS for a generic traction converter, we have developed an experimentation process. It consists of aerodynamic tests in an airport and thermal tests in a self-designed wind tunnel. The objective of this method is the complete characterisation of the HPHS and thereby, the prediction of the behaviour of the refrigeration system for the real operation of a train. During the aerodynamic tests we have deduced the relationship between the air-flow through the HPHS and the train speed. Besides, we have analysed some extra phenomena, such as the double-cavity flow and the air-leakage of the system. The thermal study has allowed us to determine the thermal resistance network, working out the influence of the power losses of the inverter and the air velocity in the overall efficiency of the HPHS. In addition, we have examined transient response and the importance of natural convection. The paper summarizes both series of tests carried out with the system subject to study and presents the main results and conclusions.

	Comparison of Fields Emitted from High Frequency Silicon-Integrated, Microfabricated Inductors By Michal LAZARCZYK, Terence O'DONNELL, Noel BARRY, Ronan MEERE	[View] [Download]
Abstract: Technological progress and development is bringing commercially available power supplies integrated in a single chip closer and closer to reality. One of crucial milestones in this process is integration of inductors with magnetic core onto a silicon substrate. Such inductors enable full integration of a switch mode voltage converter in a single chip, provided that the switching frequency is high enough. This significant increase of switching frequency creates new problems for IC designers and engineers, especially related to electromagnetic interferences and compatibility. This paper presents simulated electromagnetic fields emitted by two commonly used designs of magnetic core inductors and an air core coil of corresponding inductance. Comparison of emitted fields is based on simulation results obtained with Ansoft Maxwell 3D. The aim of the work is to determine levels of radiation in silicon die and above it in order to identify problems that may rise in IC design, as well as exploring the feasible advantages and drawbacks of possible shielding.

	Design of the Fixed Frequency Controlled Piezoelectric Transformer based DC/DC converter By Yuan-Ping LIU, Dejan VASIC, FranÃ§ois COSTA, Wen-Jong WU, Chih-Kung LEE	[View] [Download]
Abstract: Piezoelectric transformers (PT) converters show some difficulties to work in the case of the variable load at fixed frequency. PTs can be designed to achieve these problems, but the size of the PT may become larger. In fact, the selection of the circuit topologies and the control methods influence the size and the efficiency of the PT converter. Two rectifiers (half-wave rectifier and the full-wave rectifier) were compared and two control methods (PWM control and burst mode control) were compared according to the efficiency of the converter. The full-wave rectifier and the burst-mode hysteresis control are the better choice. The hysteresis control was also proposed to improve the dynamic response of the burst-mode control.

	Direct Substrate Cooling of Power Electronics By Robert SKURIAT, Mark JOHNSON	[View] [Download]
Abstract: Liquid jet impingement can be used to efficiently generate high heat transfer coefficients for cooling. However, optimization of the jet impingement array is complicated as a large number of geometrical parameters, such as array size, jet spacing and jet diameter affect performance. In the studies described in this paper a custom designed half-bridge substrate tile, supporting two IGBT and two diode dies, is cooled using liquid jet impingement onto the underside of the active metal brazed (AMB) Aluminium Nitride substrate tile. In order to reduce redundancy in the cooling system, the impingement array is designed to directly target the hot spots on the underside of the tile. A number of jet impingement arrays are designed and compared in order to determine which impingement geometry provides the most effective cooling. The performance of each cooling array is presented as a function of temperature rise of the IGBT dies with fluid flow rate, pressure drop across the cooler and pumping power required. A 6 x 6 array of 0.5mm diameter jets spaced at 2mm is found to be the most efficient. At a pumping power requirement of 5 W the jet impingement cooler is able to maintain the IGBT dies at a temperature 22.38Â°C above the water temperature while dissipating 400 W of heat. Further experimental work is discussed.

	Domestic Induction Heating Impedance Modeling Including Windings, Load, and Ferrite Substrate By Jesus ACERO, Rafael ALONSO, Luis Angel BARRAGAN, Claudio CARRETERO, Oscar LUCIA, Ignacio MILLAN, Jose Miguel BURDIO	[View] [Download]
Abstract: Integral expressions of the equivalent impedance of flat-type coils for induction heating systems are derived. These expressions are obtained by integration the analytical solution of the field generated by a circular filamentary current placed between two linear and homogeneous semi-infinite media. It is considered that the windings are wound with a round wire. The model also gives the magnetic field in the cross section of the windings, which is necessary to calculate the proximity losses in the cables. The solution is given in terms of Bessel function integrals, which are calculated by means of MATLAB. Several prototypes having different turns were constructed and tested with different loads. Measurements confirm the validity of the analytical models.

	Dynamic Junction Temperature Calculation and Measurement by Four-Pole Theory and Complex Fourier Series By Thomas KOMMA, Walter KIFFE	[View] [Download]
Abstract: The development of power supply technology has always been associated with the need for further miniaturization. This means that power semiconductors must be mounted at short distances on the same heat sink. Adjacent power semiconductors have an increasing influence on the chip temperature. The maximum junction temperatures, which are specified by the manufacturer under all operating conditions, may not be exceeded. As a rule, the chip temperatures are calculated on the basis of the losses and thermal impedance of a power semiconductor according to manufacturerâ€™s specifications. The following paper presents a procedure for determining the junction temperatures of power semiconductors in switch-mode power supplies, considering common heat-sink and arbitrary power-loss functions.

	Experimental Characterisation and Modelling of High-Voltage IGBT Modules Off-State Thermal Instability By Alberto CASTELLAZZI, Jose SAIZ, Michel MERMET-GUYENNET	[View] [Download]
Abstract: This paper proposes the experimental characterization and modeling of thermal runaway phenomena affecting high-voltage devices in the blocking state. In particular, it considers 6.5 kV rated multi-chip IGBT modules, of the kind employed in railway traction applications, showing how temperature and reverse bias voltage influence the off-state power losses and how the same thermal design may yield thermal instability for devices of different manufacturers. Additionally, evidence is shown of significant temperature mismatches for the chips within a module, which enhance the risk of failure. In order to analyze all of these effects, an advanced modeling technique is applied, which couples analytical models of semiconductor physics with a 3D numerical model of thermal effects. This allows for an in-depth, still handy analysis, useful for optimized and reliable thermal design.

	Fabrication of bottom die substrate solderless interconnection based on nano copper wires By Van-Hai NGUYEN	[View] [Download]
Abstract: Direct Copper Bonded (DBC) bottom die substrate attachment is usually ensured by solder joints but with regard to reliability it remains the weakest component of the package. The sustained trend for high power density requires new interconnection technologies. Nano-wires seem to be a promising candidate for interconnection applications in power electronics and microelectronics [1-5]. This paper presents the fabrication process of an innovative solderless interconnection based on copper nano-wires by electroplating process, itself using the Anodic Aluminum Oxide (AAO) template. Some mechanical and electrical characterizations are investigated in order to evaluate this interconnection technology.

	Loss eveluation of ac filter inductor core on a PWM Inverter By Toshihisa SHIMIZU	[View] [Download]
Abstract: Iron loss of an AC filter inductor used in a PWM inverter is discussed based on a dynamic minor loop method developed by the authors. A distinctive feature of the dynamic minor loop method is that the instantaneous iron loss of the AC filter inductor can be measured during every switching period of the inverter, and the instantaneous iron loss distribution during one cycle of the output frequency cycle can be produced using this data. The shape of the distribution changes with both the modulation method of the inverter and the load conditions, so that this method is suitable for characterization of the iron loss. Iron loss of the AC filter inductor can be categorized as two types; one type is high frequency loss, which is caused by the switching ripple current, and the other is low frequency loss caused by the low frequency output current. High frequency loss is usually much higher than low frequency loss; therefore, mainly the high frequency loss was evaluated in this study. The instantaneous iron loss of an AC filter inductor and the total loss under various conditions of the PWM inverter are measured, and the relationships between the output current and the iron loss, the DC-bus voltage and the iron loss, and the power factor and the iron loss are discussed.

	Multiobjective Optimal Design of High Frequency Transformers Using Genetic Algorithms By Christophe VERSELE, Olivier DEBLECKER, Jacques LOBRY	[View] [Download]
Abstract: This paper deals with the multiobjective optimization design of high frequency transformers using genetic algorithms. In its most general form, the design problem requires minimizing the mass or overall dimensions of the core and windings as well as the loss of the transformer while ensuring the satisfaction of a number of constraints. In this contribution, the area product (i.e. the product of the core cross section and the winding area) and the power loss are used as objective functions whereas the operating frequency and the maximum flux density are chosen as optimization variables. The constraints include, as for them, appropriate limits on efficiency, maximum surface temperature rise and maximum ratio no-load/full load current. The area product is optimized in place of weight or volume of the transformer because these two quantities can be easily expressed in terms of area product. It is an elegant mean to limit the number of objective functions. The major advantage of the suggested design procedure is that it proposes to the designer a set of optimal transformers â€“ instead of a single solution â€“ so he can choose a posteriori which of them best fits the application under consideration. Finally, in order to illustrate the design procedure, the optimal design of a transformer supplied with square voltage waveform is performed and the results are discussed.

	New power electronics components concept for automated manufacturing By Ivan JOSIFOVIC, Jelena POPOVIC, Braham FERREIRA	[View] [Download]
Abstract: This paper introduces a new concept for surface mount technology (SMT) automated manufacturing of power converters â€“ PCB Power Sandwich. The Power Sandwich manufacturing method employs new x-dimension (x-dim) components, having the same height (x) and double sided SMT electrical terminations. The components are stacked between planar substrates and soldered on both, top and bottom sides using the multilayer Power Sandwich assembly process. By arranging the components in different stack layers an increase in power density, better heat removal and improved EMI performance of power converters can be achieved. New x-dim components enable fully SMT automated power converters manufacturing with short production time and low assembly cost.

	Over-current turn-off failure in high voltage IGBT modules under clamped inductive load By Xavier PERPINYA, Jesus URRESTI-IBAÃ‘EZ, Jean-FranÃ§ois SERVIERE, Xavier JORDA, Salvador HIDALGO, JosÃ© REBOLLO, Michel MERMET-GUYENNET	[View] [Download]
Abstract: Considering typical conditions of railway traction applications, this paper presents an experimental and simulative analysis of over-current turn-off failure in IGBT devices packaged in parallel within IGBT multichip modules. Extensive experimental analysis is carried out by means of a dedicated test-circuit. Thus, for greater insight, electro-thermal simulations at device level have been carried out. The results show that mismatches in the electro-thermal properties of the IGBT device during transient operation can lead to uneven power dissipation, significantly enhancing the risk of failure.

	Real-Time Comparison of Power Module Failure Modes under In-service Conditions By Mahera MUSALLAM, Mark JOHNSON, Chunyan YIN , Chris BAILEY	[View] [Download]
Abstract: In order to meet the through-life reliability targets for power modules, it is critical to understand the response of typical wear-out mechanisms, for example wire-bond lifting and solder degradation, to in-service environmental and load-induced thermal cycling. Application of accurate wear-out models can identify the dominant failure mechanisms at the design stage and can be employed in reliability assessment and health management under in-service conditions. The work in this paper presents the effect of power cycling frequency, load current and mean temperature on temperature variations within the power module structure and its impact on the life consumption for two common wear-out mechanisms (the bond wire and the substrate-solder). Compact real-time thermal models combined with physics of failure based reliability analysis are used to identify the dominant failure mechanism and predict the life-time of the power module for each thermal cycling condition. It is shown that bond wire degradation is the dominant failure mechanism for all power cycling conditions whereas substrate solder failure dominates for externally applied (ambient or passive) thermal cycling. In addition to informing the design process and enabling real-time health management, the knowledge gained from these studies can be used to design thermal cycling experiments for selected failure mechanisms.

	Requirements on the Power Cycling Capability of IGBT modules in Traction Applications By Andreas NAGEL, Fabian QUAST	[View] [Download]
Abstract: Modern railway traction converters are equipped with IGBT-modules. Due to the mode of operation and a service lifetime of 30 years, typically specified for traction applications, the cycling capability is an important issue in converter design. The requirements from the application are summarized and design targets for the next generation of IGBT modules are discussed in this paper.

	Voltage and Current Ripple Considerations for Improving Lifetime of Supercapacitors Used for Energy Buffer Applications at Converter Inputs By Supratim BASU, TORE UNDELAND	[View] [Download]
Abstract: While supercapacitors offer high power density, high cycling capability and mechanical robustness, voltage and current ripple from downstream PWM converters can result in their overcharging or heating resulting in their lifetime reduction. This paper discusses how a simple novel design scheme of using a very low value series inductance significantly increases capacitor lifetime.