EPE Association: EPE 2022 - DS2c: Solid State Transformers

EPE 2022 - DS2c: Solid State Transformers
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 02: Power Converter Topologies and Design > EPE 2022 - DS2c: Solid State Transformers

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   A Compact Solid State Transformer for Replacing Conventional Medium Power Transformer in Weight-Critical Applications
By Leon FAUTH [View]
[Download]

Abstract: In certain weight-sensitive applications requiring galvanic isolation, conventional transformers can be of disadvantage due to their high weight and volume. Solid state transformers allow to overcome this issue. The volume can be further reduced by eliminating large dc storage capacitors, resulting in a straight AC/AC converter system based on a resonance converter.

   A Multi-port Smart Transformer for Green Airport Electrification
By Giampaolo BUTICCHI [View]
[Download]

Abstract: Green transportation and renewable energy production have attracted a global attention due to the needs of decreasing the environmental impact and still sustain increased energy needs. In this framework, the aircraft and airports are facing a profound renovations towards green technologies, among which the electrical ones are playing a central role. This paper explores how a Smart Transformer can upgrade the existing airport power system, enabling an efficient interface for renewable energy, electric vehicles and the future hybrid/electric aircraft, substituting the ground power units and enabling a smarter behavior of the electrical grid.

   Configurable ISOP-IPOP DC-DC Converter for Universal Solid-State Transformer
By Pramod APTE [View]
[Download]

Abstract: This paper presents the investigation of configurable DC-DC converter for a Universal Solid-State Transformer with a wide input voltage range. The system design for the combination of the Active Front End (AFE) and the DC-DC converter is analysed. A DC-DC converter solution with configurable series orparallel input connection is proposed.

   Evaluation of Core Losses in Transformers for Three-phase Multi-level DAB Converters
By Babak KHANZADEH [View]
[Download]

Abstract: This paper provides closed-form formulas for estimating the core losses of three-phase transformersexcited with multi-level converters for dual active bridge (DAB) applications. The formulas are derivedby applying the improved generalized Steinmetz equation with approximated flux waveforms generatedfrom one of the windings. The effect of different winding configurations on the estimated losses isstudied. The results are validated with MATLAB simulations, and their applicability for three-phasemulti-level DAB converters is investigated.It is shown that for the YY and the __ configurations, an estimation error of less than 7.5\% and 11.5\%,respectively, can be achieved for most phase shifts between 0 and 20 degrees. It is highest when thedistribution of the leakage inductance is more uniform between the primary and the secondary sides.Moreover, effect of the transition times of the bridges on the estimation error is also studied. It isestablished that estimating the losses from the winding, whose transition time is the largest, results inlower estimation error. It is demonstrated that using the parameters of the _ side results in less estimationerror for the Y_ and the _Y configurations and most of the studied designs. The maximum estimationerror for these two winding configurations is below 8.5\% for phase shifts below 20 degrees.

   Fault Current Capability Assessment of Low-Voltage side Inverters in Smart-Transformers
By Thiago PEREIRA [View]
[Download]

Abstract: The Smart Transformer (ST) arises as one promising solution for the modern electric grid by providingancillary services to support AC and DC distribution grid. In this context, as the classical low-frequencytransformer (LFT), the ST is prone to experience overload conditions caused by faults and peak loads.However, unlike the LFT, the overcurrent capability of the ST is further limited by the thermal timeconstant of the power semiconductors. Thus, since the overload operation has been only partially investigated, this paper proposes and presents a comprehensive analysis of the LV-side power converter under normal and overload conditions to estimate its overcurrent capability. For this purpose, the LV-side inverter is assessed in terms of power losses considering continuous and discontinuous modulation strategies and different power semiconductor technologies along with multiple types of cooling systems.

   Power control of LCR-DAB converter with phase shift in fixed switching frequency
By Seung-Hyuk BAEK [View]
[Download]

Abstract: This paper proposes the power control method of the Loosely Coupled Resonant Dual-Active-Bridge (LCR-DAB) converter using Phase-Shift Modulation (PSM) of a conventional DAB converter. In this paper, to apply PSM to the LCR-DAB converter, the impedance characteristics were analyzed to design an efficient operating frequency for the LCR-DAB converter. In addition, the power equation of the LCR-DAB converter was derived to control the power using the phase, which is the control variable of the PSM. Experiments were performed on the 840W prototype LCR-DAB converter to verify the validity of the proposed power control method.

   Predictive Control of Power Electronics Autotransformer for Mitigating Three-Phase Grid Current Unbalance in Railway Supply Systems
By Tabish MIR [View]
[Download]

Abstract: In order to mitigate the unbalance of three-phase grid currents that is commonly prevalent in single-phase railway supply lines, a predictively controlled power electronics autotransformer is proposed in this paper. It comprises of a pair of back to back single-phase voltage source converters that are strategically connected between different phases of the three-phase grid. Using finite control setmodel predictive control, the converters are intelligently controlled with a regulated DC link, to draw balanced sinusoidal three-phase grid currents at nearly unity input power factor, even as the rail system connects as a single-phase load on the three-phase network. This in turn helps in maintaining the balance and quality of three-phase voltage supply at the point of common coupling.

   Single Transformer, MMC based MV Power Electronic Traction Transformer
By Simon FUCHS [View]
[Download]

Abstract: To reduce the number of modules and the number of transformers of existing power electronic traction transformers (PETTs), a novel PETT topology based on the principle of the modular multilevel converter (MMC) and the dual active bridge (DAB) is introduced. The paper explains the operation principle of the proposed PETT and compares the PETT to two existing concepts.

EPE 2022 - DS2c: Solid State Transformers
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 02: Power Converter Topologies and Design > EPE 2022 - DS2c: Solid State Transformers
	[return to parent folder]

	A Compact Solid State Transformer for Replacing Conventional Medium Power Transformer in Weight-Critical Applications By Leon FAUTH	[View] [Download]
Abstract: In certain weight-sensitive applications requiring galvanic isolation, conventional transformers can be of disadvantage due to their high weight and volume. Solid state transformers allow to overcome this issue. The volume can be further reduced by eliminating large dc storage capacitors, resulting in a straight AC/AC converter system based on a resonance converter.

	A Multi-port Smart Transformer for Green Airport Electrification By Giampaolo BUTICCHI	[View] [Download]
Abstract: Green transportation and renewable energy production have attracted a global attention due to the needs of decreasing the environmental impact and still sustain increased energy needs. In this framework, the aircraft and airports are facing a profound renovations towards green technologies, among which the electrical ones are playing a central role. This paper explores how a Smart Transformer can upgrade the existing airport power system, enabling an efficient interface for renewable energy, electric vehicles and the future hybrid/electric aircraft, substituting the ground power units and enabling a smarter behavior of the electrical grid.

	Configurable ISOP-IPOP DC-DC Converter for Universal Solid-State Transformer By Pramod APTE	[View] [Download]
Abstract: This paper presents the investigation of configurable DC-DC converter for a Universal Solid-State Transformer with a wide input voltage range. The system design for the combination of the Active Front End (AFE) and the DC-DC converter is analysed. A DC-DC converter solution with configurable series orparallel input connection is proposed.

	Evaluation of Core Losses in Transformers for Three-phase Multi-level DAB Converters By Babak KHANZADEH	[View] [Download]
Abstract: This paper provides closed-form formulas for estimating the core losses of three-phase transformersexcited with multi-level converters for dual active bridge (DAB) applications. The formulas are derivedby applying the improved generalized Steinmetz equation with approximated flux waveforms generatedfrom one of the windings. The effect of different winding configurations on the estimated losses isstudied. The results are validated with MATLAB simulations, and their applicability for three-phasemulti-level DAB converters is investigated.It is shown that for the YY and the __ configurations, an estimation error of less than 7.5\% and 11.5\%,respectively, can be achieved for most phase shifts between 0 and 20 degrees. It is highest when thedistribution of the leakage inductance is more uniform between the primary and the secondary sides.Moreover, effect of the transition times of the bridges on the estimation error is also studied. It isestablished that estimating the losses from the winding, whose transition time is the largest, results inlower estimation error. It is demonstrated that using the parameters of the _ side results in less estimationerror for the Y_ and the _Y configurations and most of the studied designs. The maximum estimationerror for these two winding configurations is below 8.5\% for phase shifts below 20 degrees.

	Fault Current Capability Assessment of Low-Voltage side Inverters in Smart-Transformers By Thiago PEREIRA	[View] [Download]
Abstract: The Smart Transformer (ST) arises as one promising solution for the modern electric grid by providingancillary services to support AC and DC distribution grid. In this context, as the classical low-frequencytransformer (LFT), the ST is prone to experience overload conditions caused by faults and peak loads.However, unlike the LFT, the overcurrent capability of the ST is further limited by the thermal timeconstant of the power semiconductors. Thus, since the overload operation has been only partially investigated, this paper proposes and presents a comprehensive analysis of the LV-side power converter under normal and overload conditions to estimate its overcurrent capability. For this purpose, the LV-side inverter is assessed in terms of power losses considering continuous and discontinuous modulation strategies and different power semiconductor technologies along with multiple types of cooling systems.

	Power control of LCR-DAB converter with phase shift in fixed switching frequency By Seung-Hyuk BAEK	[View] [Download]
Abstract: This paper proposes the power control method of the Loosely Coupled Resonant Dual-Active-Bridge (LCR-DAB) converter using Phase-Shift Modulation (PSM) of a conventional DAB converter. In this paper, to apply PSM to the LCR-DAB converter, the impedance characteristics were analyzed to design an efficient operating frequency for the LCR-DAB converter. In addition, the power equation of the LCR-DAB converter was derived to control the power using the phase, which is the control variable of the PSM. Experiments were performed on the 840W prototype LCR-DAB converter to verify the validity of the proposed power control method.

	Predictive Control of Power Electronics Autotransformer for Mitigating Three-Phase Grid Current Unbalance in Railway Supply Systems By Tabish MIR	[View] [Download]
Abstract: In order to mitigate the unbalance of three-phase grid currents that is commonly prevalent in single-phase railway supply lines, a predictively controlled power electronics autotransformer is proposed in this paper. It comprises of a pair of back to back single-phase voltage source converters that are strategically connected between different phases of the three-phase grid. Using finite control setmodel predictive control, the converters are intelligently controlled with a regulated DC link, to draw balanced sinusoidal three-phase grid currents at nearly unity input power factor, even as the rail system connects as a single-phase load on the three-phase network. This in turn helps in maintaining the balance and quality of three-phase voltage supply at the point of common coupling.

	Single Transformer, MMC based MV Power Electronic Traction Transformer By Simon FUCHS	[View] [Download]
Abstract: To reduce the number of modules and the number of transformers of existing power electronic traction transformers (PETTs), a novel PETT topology based on the principle of the modular multilevel converter (MMC) and the dual active bridge (DAB) is introduced. The paper explains the operation principle of the proposed PETT and compares the PETT to two existing concepts.