EPE Association: EPE 2016 - DS1b: Hard and Soft Switching Techniques

EPE 2016 - DS1b: Hard and Soft Switching Techniques
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 02: Power Converter Topologies and Design > EPE 2016 - DS1b: Hard and Soft Switching Techniques

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   A current-fed DC/DC converter for the efficient charging of HV capacitors in mobile applications
By Tristan WEINERT [View]
[Download]

Abstract: This paper suggests a current-fed double inductor push-pull converter for the use as a preamplifier stageof a constant current charger for HV capacitors. With this converter it is possible to offer a wide inputvoltage range for the use in mobile applications with a 24V or a 48V battery. A novel snubber techniquefor current-fed converters is introduced, so that transistor conduction losses can be reduced significantly.The main part of the snubber is an active transformer short-circuit which eliminates the negative impactof the transformer leakage on the MOSFETs Drain-Source Voltage, by forcing the beginning of the commutationprocess earlier. Due to the reduction over the overvoltages MOSFETs with smaller BreakdownVoltage can be used leading to smaller On-Resistances. In a prototype the conduction losses were reducedto 55 \%. The introduction of the transformer short-circuit can be achieved easily and inexpensiveby replacing two diodes of the output rectifier bridge with MOSFETs.Additionally a small signal model of the current-fed double inductor push-pull converter is derived. TheHV capacitor load profile demands particular requirements to the control, which will be closer observed.It will be shown that the best solution is a feed-forward of the link current to the input stage control.Otherwise a constant control deviation of the link voltage can occur.

   A Family of High DC Gain Step-up Non-isolated Converters Based on a New Hybrid Passive Switching Cell
By Manxin CHEN [View]
[Download]

Abstract: By combining a switched-capacitor cell with a switched-inductor cell, a new passive switching cell is defined. It is inserted in basic converters to get step-up regulators providing a large dc gain as required in applications powered by environmental-friendly sources of energy. Simulation and experiments show the superiority of the proposed converter compared with available solutions with the same number of reactive elements.

   A Novel Control Concept for High-Efficiency Power Conversion with the Bidirectional Non-inverting Buck-Boost Converter
By Zhe YU [View]
[Download]

Abstract: This paper presents a novel control concept for the bidirectional non-inverting buck-boost converter to achieve extreme high-efficiency power conversion. The duty cycle, duty ratios and time delays of the PWM control signals for the switches are modulated depending on operating points to minimize the power losses in the converter. A 3kW prototype of the converter using SiC MOSFETs has been designed and tested for the verification of the control concept. Measurement results show that the prototype achieves power efficiency between 97.79\% and 99.60\% over a power range 'input voltage from 300V to 500V, output voltage from 200V to 600V and output current from 1A to 5A'.

   A Study of Soft Switching DC-DC Converter Under Delta-Sigma Modulation
By Atsushi HIROTA [View]
[Download]

Abstract: This paper proposes a soft switching type dc-dc converter. To suppress noise levels, reformed deltasigmamodulation circuit is introduced. To reduce switching loss, the proposed converter also introducessoft switching technique.

   Analytical Investigation of the Three-Phase Single Active Bridge for Offshore Applications
By CHRISTIAN SOMMER [View]
[Download]

Abstract: This paper presents an analytical investigation of the three-phase single active bridge DC-DC converter.First, multiple operation modes have been identified, that can be distinguished by the shape of the phasecurrents. For every single operating mode, analytical equations have been derived in order to describe thecurrents of both input and output bridge. In this paper, two operating modes are selected for a detailedinvestigation in order to show the basic principle of the approach. This method can then be applied tothe other operating modes. Based on the waveforms and their parameters, the peak, average and rmscurrents of the components can be obtained. This information can be used to predict losses of both thepower electronic devices and the inductive components.

   Application of GaN Power Transistors in a 2.5 MHz LLC DC/DC Converter for Compact and Efficient Power Conversion
By Cornelius ARMBRUSTER [View]
[Download]

Abstract: In this work a demonstrator with a switching frequency up to 2.5 MHz is shown. These comparatively high frequencies reduce the weight and the system costs of the resonant 3-kW-DC-DC-converter. The electrical properties of the implemented Gallium Nitride (GaN) power transistors enable high switching frequencies while maintaining high efficiency. The presented converter has a power density of approximately 3 W/cm³. The total efficiency of the converter is higher than 90 \% for all operation points above 1/5 of the nominal load. Exceptional high efficiency of 94.5 \% can be reached at ½ of the nominal load and a switching frequency of 2 MHz. Possible improvements are defined and could be reached by adding a continuous dead time control as well as adapting the driver circuit of the synchronous rectification.

   Comparison of modeling switching losses of an IGBT based on the datasheet and an experimentation
By DOUNIA OUSTAD [View]
[Download]

Abstract: This paper focuses on the prediction and the study of the veracity of a losses model (both conductionand switching losses) in IGBT power modules used for electric vehicle applications. This articleshows a test case based on an experimental estimation of losses with a double pulse test circuit and acircuit model based on the use of ANSYS solver Circuit - Simplorer©. This modeling is onlygrounded in the knowledge of the characteristics of the modules from datasheets. Then, it is comparedwith experimental measurements. The veracity of these models is evaluated, the errors are quantifiedand if necessary, additional characterizations that will be performed to complete the data fromdatasheets will be identified. An estimation of the losses with sufficient accuracy will be obtained.

   Current Mismatch in Paralleled Phases of High Power SiC Modules due to Threshold Voltage Unsymmetry and Different Gate-Driver Concepts
By Roman HORFF [View]
[Download]

Abstract: This paper analyzes the influence of the threshold voltage on the parallel connection of three phases of a high power SiC MOSFET module. The current mismatch and the resulting switching loss distribution between paralleled phases will be investigated.Two different gate-drive circuit concepts will be tested. The influence of the choice of the gate-resistor arrangement will be presented regarding the dynamic current distribution and switching losses.

   Development of a Class D Resonant Power Converter for Radio Frequency heating
By Unnikrishnan RAVEENDRAN NAIR [View]
[Download]

Abstract: Resonant converters find widespread application in the industries for Radio Frequency (RF) heating. Various topologies using vacuum tubes are currently used for such application. Realizing class D topologies with solid state devices could provide more reliability. This work explores possibility of developing a 1kW Class D resonant converter for heating applications using Si/SiC MOSFETs which can replace vacuum tube RF generators. A resonant gate driver which enables efficient switching and modularity along with some practical aspects in implementing a class D converter is discussed here. The results from the developed class D converter and the suggestions for improvement are also highlighted here.

   Efficiency Analysis of a High Frequency PS-ZVS Isolated Unidirectional Full-Bridge DC-DC Converter Based on SiC MOSFETs
By Abdullah EIAL AWWAD [View]
[Download]

Abstract: In this work, the static and dynamic characteristics of a new double-trench SiC MOSFET are experimentallyinvestigated and compared to two different available commercial SiC MOSFETs. The SiC devices areapplied in a ZVZCS Phase-Shifted Full-Bridge converter which uses the parasitic leakage inductance of thetransformer to achieve soft switching. A practical method to break down the converter losses based onseparating the measured semiconductor and magnetic losses is proposed and compared to an analytical lossmodel. The experimental results show several advantages of using SiC MOSFETs as well as ZVZCS in theconverter. The main results can be summarized as elimination of the freewheeling circulating current mode,clamping the overshoot voltage across the rectifier diodes and achieving soft switching in a wide powerload range without additional auxiliary circuits or resonant inductor. Experimental results for a 10kW, (100-250) kHz prototype show an efficiency of up to 98,1\% for the whole converter.

   Estimation of Switching Losses in Resonant Converters Based on Datasheet Information
By Christian OEDER [View]
[Download]

Abstract: The class of resonant converters is very attractive due to its ability to achieve nearly lossless switching by using zero current or zero voltage switching (ZCS/ZVS) for the switching devices in the input bridge. Since most switched-mode power supplies (SMPS) today use MOSFETs as semiconductor devices, a ZVS operation is typically preferred. However, the ongoing trend towards higher switching frequencies makes reaching of ZVS more and more difficult. Thus, a (partial) loss of ZVS might be the consequence, making the need for a reasonable estimation of the occurring losses of vital importance. Due to the half- or full-bridge configuration, this estimation becomes much more complex compared to a traditional hard-switched boost or buck converter. This paper gives a detailed insight into the switching transients of resonant converters and proposes a proper test circuit. A powerful method is presented to estimate the generated switching and driving losses during the turn-on event of the switches in case of incomplete ZVS. This approach is purely based on the semiconductors' datasheet information. No additional knowledge about the internal device structure is necessary.

   LLC Resonant Power Converter with Quality Factor Limiter
By Cezary WOREK [View]
[Download]

Abstract: This paper presents the concept of a high-power DC/DC class of converters with a Q-factor limiter based on aserial LLC type resonant circuit. The Q-factor limiter allows highly accurate determination of thevoltage/current limit values in the resonant circuit's passive elements thus significantly increasing immunity totransient states. Properties of the proposed topology are confirmed by the results of simulations andmeasurements performed with a laboratory model.

   Modification of Existing Test-Bench for Soft-Switching Application
By Johannes VOSS [View]
[Download]

Abstract: This paper presents a modification of a test bench which has been built for device characteristation.The test bench is able to measure the static losses (blocking and forward conduction) and the dynamic losses (turn on and turn off). To have a comparison of devices designed for soft-switching applications and devices for converters in hard-switching applications the existing test bench is modified to allow measurements for devices in soft-switching conditions. The existing test bench is prepared for testing IGBTs, IGCTs, IETOs and other similar devices.

   Modulation and Capacitor Voltage Balancing Control of a Four-Level Active-Clamped Dual-Active-Bridge DC-DC Converter
By Alber FILBA-MARTINEZ [View]
[Download]

Abstract: This paper proposes and demonstrates the feasibility of a dual-active-bridge converter built upon four-level active-clamped legs. A suitable modulation pattern is defined. The dc-link capacitor voltage balancing is analyzed and a proper balancing control is designed. The topology, modulation, and balancing control performance are validated through the steady state and transient responses obtained with a set of simulation and experimental tests. An experimental prototype has been built for the experimental tests composed of four four-level active-clamped converter legs and controlled with a dSPACE control platform.

   Performance of a GaN-HEMT Synchronous Boost Converter in ZVS and Hard Switching Mode
By Michael EBLI [View]
[Download]

Abstract: The loss contribution of a 2.3kW synchronous GaN-HEMT boost converter for an input voltage of250V and an output voltage of 500V was analyzed. A simulation model which consists of two partsis introduced. First, a physics-based model is used to determine the switching losses. Then, a systemsimulation is applied to calculate the losses of the specific elements. This approach allows a fast andaccurate system evaluation as required for further system optimization.In this work, a hard- and a zero-voltage turn-on switching converter are compared. Measurements wereperformed to verify the simulation model, showing a good agreement. A peak efficiency of 99\% wasachieved for an output power of 1.4kW. Even with an output power above 400W, it was possible toobtain a system efficiency exceeding 98 \%.

   Wide Range ZVS Operation of Dual Active Bridge DC-DC Converters using Adaptive Modulation and Low Coupling Factor Transformers
By Jan RIEDEL [View]
[Download]

Abstract: One of the central requirements of a Dual Active Bridge (DAB) converter is to operate under ZeroVoltage Switching (ZVS) conditions, to reduce switching losses and increase operating efficiency. Thispaper shows how frequency domain analysis can be used to design and operate a DAB to ensure ZVSacross the entire operating range by using transformers with a reduced winding coupling factor andadaptive 3-level bridge modulation, while also including second order effects. The approach is shown toachieve experimentally measured efficiencies between 96.5\% and 98.5\% over the entire power range foran optimised DAB converter stage (>1 kW).

EPE 2016 - DS1b: Hard and Soft Switching Techniques
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 02: Power Converter Topologies and Design > EPE 2016 - DS1b: Hard and Soft Switching Techniques
	[return to parent folder]

	A current-fed DC/DC converter for the efficient charging of HV capacitors in mobile applications By Tristan WEINERT	[View] [Download]
Abstract: This paper suggests a current-fed double inductor push-pull converter for the use as a preamplifier stageof a constant current charger for HV capacitors. With this converter it is possible to offer a wide inputvoltage range for the use in mobile applications with a 24V or a 48V battery. A novel snubber techniquefor current-fed converters is introduced, so that transistor conduction losses can be reduced significantly.The main part of the snubber is an active transformer short-circuit which eliminates the negative impactof the transformer leakage on the MOSFETs Drain-Source Voltage, by forcing the beginning of the commutationprocess earlier. Due to the reduction over the overvoltages MOSFETs with smaller BreakdownVoltage can be used leading to smaller On-Resistances. In a prototype the conduction losses were reducedto 55 \%. The introduction of the transformer short-circuit can be achieved easily and inexpensiveby replacing two diodes of the output rectifier bridge with MOSFETs.Additionally a small signal model of the current-fed double inductor push-pull converter is derived. TheHV capacitor load profile demands particular requirements to the control, which will be closer observed.It will be shown that the best solution is a feed-forward of the link current to the input stage control.Otherwise a constant control deviation of the link voltage can occur.

	A Family of High DC Gain Step-up Non-isolated Converters Based on a New Hybrid Passive Switching Cell By Manxin CHEN	[View] [Download]
Abstract: By combining a switched-capacitor cell with a switched-inductor cell, a new passive switching cell is defined. It is inserted in basic converters to get step-up regulators providing a large dc gain as required in applications powered by environmental-friendly sources of energy. Simulation and experiments show the superiority of the proposed converter compared with available solutions with the same number of reactive elements.

	A Novel Control Concept for High-Efficiency Power Conversion with the Bidirectional Non-inverting Buck-Boost Converter By Zhe YU	[View] [Download]
Abstract: This paper presents a novel control concept for the bidirectional non-inverting buck-boost converter to achieve extreme high-efficiency power conversion. The duty cycle, duty ratios and time delays of the PWM control signals for the switches are modulated depending on operating points to minimize the power losses in the converter. A 3kW prototype of the converter using SiC MOSFETs has been designed and tested for the verification of the control concept. Measurement results show that the prototype achieves power efficiency between 97.79\% and 99.60\% over a power range 'input voltage from 300V to 500V, output voltage from 200V to 600V and output current from 1A to 5A'.

	A Study of Soft Switching DC-DC Converter Under Delta-Sigma Modulation By Atsushi HIROTA	[View] [Download]
Abstract: This paper proposes a soft switching type dc-dc converter. To suppress noise levels, reformed deltasigmamodulation circuit is introduced. To reduce switching loss, the proposed converter also introducessoft switching technique.

	Analytical Investigation of the Three-Phase Single Active Bridge for Offshore Applications By CHRISTIAN SOMMER	[View] [Download]
Abstract: This paper presents an analytical investigation of the three-phase single active bridge DC-DC converter.First, multiple operation modes have been identified, that can be distinguished by the shape of the phasecurrents. For every single operating mode, analytical equations have been derived in order to describe thecurrents of both input and output bridge. In this paper, two operating modes are selected for a detailedinvestigation in order to show the basic principle of the approach. This method can then be applied tothe other operating modes. Based on the waveforms and their parameters, the peak, average and rmscurrents of the components can be obtained. This information can be used to predict losses of both thepower electronic devices and the inductive components.

	Application of GaN Power Transistors in a 2.5 MHz LLC DC/DC Converter for Compact and Efficient Power Conversion By Cornelius ARMBRUSTER	[View] [Download]
Abstract: In this work a demonstrator with a switching frequency up to 2.5 MHz is shown. These comparatively high frequencies reduce the weight and the system costs of the resonant 3-kW-DC-DC-converter. The electrical properties of the implemented Gallium Nitride (GaN) power transistors enable high switching frequencies while maintaining high efficiency. The presented converter has a power density of approximately 3 W/cm³. The total efficiency of the converter is higher than 90 \% for all operation points above 1/5 of the nominal load. Exceptional high efficiency of 94.5 \% can be reached at ½ of the nominal load and a switching frequency of 2 MHz. Possible improvements are defined and could be reached by adding a continuous dead time control as well as adapting the driver circuit of the synchronous rectification.

	Comparison of modeling switching losses of an IGBT based on the datasheet and an experimentation By DOUNIA OUSTAD	[View] [Download]
Abstract: This paper focuses on the prediction and the study of the veracity of a losses model (both conductionand switching losses) in IGBT power modules used for electric vehicle applications. This articleshows a test case based on an experimental estimation of losses with a double pulse test circuit and acircuit model based on the use of ANSYS solver Circuit - Simplorer©. This modeling is onlygrounded in the knowledge of the characteristics of the modules from datasheets. Then, it is comparedwith experimental measurements. The veracity of these models is evaluated, the errors are quantifiedand if necessary, additional characterizations that will be performed to complete the data fromdatasheets will be identified. An estimation of the losses with sufficient accuracy will be obtained.

	Current Mismatch in Paralleled Phases of High Power SiC Modules due to Threshold Voltage Unsymmetry and Different Gate-Driver Concepts By Roman HORFF	[View] [Download]
Abstract: This paper analyzes the influence of the threshold voltage on the parallel connection of three phases of a high power SiC MOSFET module. The current mismatch and the resulting switching loss distribution between paralleled phases will be investigated.Two different gate-drive circuit concepts will be tested. The influence of the choice of the gate-resistor arrangement will be presented regarding the dynamic current distribution and switching losses.

	Development of a Class D Resonant Power Converter for Radio Frequency heating By Unnikrishnan RAVEENDRAN NAIR	[View] [Download]
Abstract: Resonant converters find widespread application in the industries for Radio Frequency (RF) heating. Various topologies using vacuum tubes are currently used for such application. Realizing class D topologies with solid state devices could provide more reliability. This work explores possibility of developing a 1kW Class D resonant converter for heating applications using Si/SiC MOSFETs which can replace vacuum tube RF generators. A resonant gate driver which enables efficient switching and modularity along with some practical aspects in implementing a class D converter is discussed here. The results from the developed class D converter and the suggestions for improvement are also highlighted here.

	Efficiency Analysis of a High Frequency PS-ZVS Isolated Unidirectional Full-Bridge DC-DC Converter Based on SiC MOSFETs By Abdullah EIAL AWWAD	[View] [Download]
Abstract: In this work, the static and dynamic characteristics of a new double-trench SiC MOSFET are experimentallyinvestigated and compared to two different available commercial SiC MOSFETs. The SiC devices areapplied in a ZVZCS Phase-Shifted Full-Bridge converter which uses the parasitic leakage inductance of thetransformer to achieve soft switching. A practical method to break down the converter losses based onseparating the measured semiconductor and magnetic losses is proposed and compared to an analytical lossmodel. The experimental results show several advantages of using SiC MOSFETs as well as ZVZCS in theconverter. The main results can be summarized as elimination of the freewheeling circulating current mode,clamping the overshoot voltage across the rectifier diodes and achieving soft switching in a wide powerload range without additional auxiliary circuits or resonant inductor. Experimental results for a 10kW, (100-250) kHz prototype show an efficiency of up to 98,1\% for the whole converter.

	Estimation of Switching Losses in Resonant Converters Based on Datasheet Information By Christian OEDER	[View] [Download]
Abstract: The class of resonant converters is very attractive due to its ability to achieve nearly lossless switching by using zero current or zero voltage switching (ZCS/ZVS) for the switching devices in the input bridge. Since most switched-mode power supplies (SMPS) today use MOSFETs as semiconductor devices, a ZVS operation is typically preferred. However, the ongoing trend towards higher switching frequencies makes reaching of ZVS more and more difficult. Thus, a (partial) loss of ZVS might be the consequence, making the need for a reasonable estimation of the occurring losses of vital importance. Due to the half- or full-bridge configuration, this estimation becomes much more complex compared to a traditional hard-switched boost or buck converter. This paper gives a detailed insight into the switching transients of resonant converters and proposes a proper test circuit. A powerful method is presented to estimate the generated switching and driving losses during the turn-on event of the switches in case of incomplete ZVS. This approach is purely based on the semiconductors' datasheet information. No additional knowledge about the internal device structure is necessary.

	LLC Resonant Power Converter with Quality Factor Limiter By Cezary WOREK	[View] [Download]
Abstract: This paper presents the concept of a high-power DC/DC class of converters with a Q-factor limiter based on aserial LLC type resonant circuit. The Q-factor limiter allows highly accurate determination of thevoltage/current limit values in the resonant circuit's passive elements thus significantly increasing immunity totransient states. Properties of the proposed topology are confirmed by the results of simulations andmeasurements performed with a laboratory model.

	Modification of Existing Test-Bench for Soft-Switching Application By Johannes VOSS	[View] [Download]
Abstract: This paper presents a modification of a test bench which has been built for device characteristation.The test bench is able to measure the static losses (blocking and forward conduction) and the dynamic losses (turn on and turn off). To have a comparison of devices designed for soft-switching applications and devices for converters in hard-switching applications the existing test bench is modified to allow measurements for devices in soft-switching conditions. The existing test bench is prepared for testing IGBTs, IGCTs, IETOs and other similar devices.

	Modulation and Capacitor Voltage Balancing Control of a Four-Level Active-Clamped Dual-Active-Bridge DC-DC Converter By Alber FILBA-MARTINEZ	[View] [Download]
Abstract: This paper proposes and demonstrates the feasibility of a dual-active-bridge converter built upon four-level active-clamped legs. A suitable modulation pattern is defined. The dc-link capacitor voltage balancing is analyzed and a proper balancing control is designed. The topology, modulation, and balancing control performance are validated through the steady state and transient responses obtained with a set of simulation and experimental tests. An experimental prototype has been built for the experimental tests composed of four four-level active-clamped converter legs and controlled with a dSPACE control platform.

	Performance of a GaN-HEMT Synchronous Boost Converter in ZVS and Hard Switching Mode By Michael EBLI	[View] [Download]
Abstract: The loss contribution of a 2.3kW synchronous GaN-HEMT boost converter for an input voltage of250V and an output voltage of 500V was analyzed. A simulation model which consists of two partsis introduced. First, a physics-based model is used to determine the switching losses. Then, a systemsimulation is applied to calculate the losses of the specific elements. This approach allows a fast andaccurate system evaluation as required for further system optimization.In this work, a hard- and a zero-voltage turn-on switching converter are compared. Measurements wereperformed to verify the simulation model, showing a good agreement. A peak efficiency of 99\% wasachieved for an output power of 1.4kW. Even with an output power above 400W, it was possible toobtain a system efficiency exceeding 98 \%.

	Wide Range ZVS Operation of Dual Active Bridge DC-DC Converters using Adaptive Modulation and Low Coupling Factor Transformers By Jan RIEDEL	[View] [Download]
Abstract: One of the central requirements of a Dual Active Bridge (DAB) converter is to operate under ZeroVoltage Switching (ZVS) conditions, to reduce switching losses and increase operating efficiency. Thispaper shows how frequency domain analysis can be used to design and operate a DAB to ensure ZVSacross the entire operating range by using transformers with a reduced winding coupling factor andadaptive 3-level bridge modulation, while also including second order effects. The approach is shown toachieve experimentally measured efficiencies between 96.5\% and 98.5\% over the entire power range foran optimised DAB converter stage (>1 kW).