EPE Association: EPE 2022 - LS3c: Wide-Band Gap Power Converters

EPE 2022 - LS3c: Wide-Band Gap Power Converters
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 - LS3c: Wide-Band Gap Power Converters

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   A Wide-Input-Voltage-Range 50W Series-Capacitor Buck Converter with Ancillary Voltage Bus for Fast Transient Response in 48V PoL Applications
By Nameer KHAN [View]
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Abstract: This paper presents an auxiliary-assisted 5:1 Series-Capacitor (SC) buck converter for fast transient response in 48V Point-of-Load (PoL) automotive applications. The 5:1 SC buck converter, which is implemented as the main hybrid stage, regulates the auxiliary buffer capacitor voltage, Vaux, and consequently, delivers the average load power. By regulating Vaux, the main hybrid stage facilitates the creation of an ancillary voltage bus for on-board electronics. The high-frequency auxiliary stage precisely regulates the output voltage, Vout with a Ripple-Based Constant On-Time (RB-COT) control scheme, by utilizing the energy stored in the buffer capacitor, Caux. With no stringent transient requirements on $V\_{AUX}$, the main stage is optimized to deliver the average load power, while the auxiliary stage is designed for high-frequency operation. A 50W, 48V-to-0.8V experimental prototype was built to validate the proposed architecture. Load transients from 5 A to 29 A were applied to the prototype, resulting in an output voltage deviation of 60 mV. The system achieves a peak efficiency of 89.5\% with an output capacitance of only 720 µF and an auxiliary capacitance of 120 µF.

   Adaptive Resonant-Valley Switching for a GaN HEMT Direct AC-AC Auxiliary Resonant Commutated Pole Converter
By Kyle STEYN [View]
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Abstract: Zero-voltage zero-current switching is not guaranteed with auxiliary resonant commutated pole (ARCP) based topologies. The optimal dead-time is dependant on various parameters and cannot easily be calculated in real-time. A control technique that ensures all phase-arm switches turn on during the first resonant valley is presented. The voltage across one phase-arm switch is sampled during a turn-on transition and stored. The samples are processed by an adaptive zero-crossing algorithm and the optimal dead-time for the next switching cycle is predicted. The proposed technique was validated during a load transient and at steady-state in simulation and experimentally on a 5-kW direct ac-ac ARCP prototype.

   Experimental Demonstration of a 2.2kW Active-Clamp Converter for High-Current Wide-Voltage-Transfer Ratio Applications
By Philipp REHLAENDER [View]
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Abstract: Active-clamp forward converters are typically not applied for converters with power ratings larger than 500 W as power as the power transfer between primary and secondary is discontinuous leading to large magnetic components. This paper, however, proves that silicon carbide (SiC) devices enable this topology as a well-suitable topology for a wide voltage-transfer ratio due to the low switching losses allowing high switching frequencies reducing the size of the magnetic components. A laboratory prototype is designed using a very precise model. It employs SiC MOSFETs of 900 V for the primary and Si synchronous rectifiers of 100 V. The semiconductors are cooled with cost-efficient copper inlays, which effectiveness is demonstrated through a thermal FEM simulation. The developed prototype achieves a maximum efficiency of 95 \% while maintaining an efficiency above 92 \% for almost the entire operating region. The high efficiency and the power density of approximately 2 kW/l confirm the proposed concept. Finally, the converter is benchmarked to two LLC resonant converters (Si, SiC) and the prototype is used to verify a highly accurate steady-state model showing errors below 1 \%.

EPE 2022 - LS3c: Wide-Band Gap Power Converters
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 - LS3c: Wide-Band Gap Power Converters
	[return to parent folder]

	A Wide-Input-Voltage-Range 50W Series-Capacitor Buck Converter with Ancillary Voltage Bus for Fast Transient Response in 48V PoL Applications By Nameer KHAN	[View] [Download]
Abstract: This paper presents an auxiliary-assisted 5:1 Series-Capacitor (SC) buck converter for fast transient response in 48V Point-of-Load (PoL) automotive applications. The 5:1 SC buck converter, which is implemented as the main hybrid stage, regulates the auxiliary buffer capacitor voltage, Vaux, and consequently, delivers the average load power. By regulating Vaux, the main hybrid stage facilitates the creation of an ancillary voltage bus for on-board electronics. The high-frequency auxiliary stage precisely regulates the output voltage, Vout with a Ripple-Based Constant On-Time (RB-COT) control scheme, by utilizing the energy stored in the buffer capacitor, Caux. With no stringent transient requirements on $V\_{AUX}$, the main stage is optimized to deliver the average load power, while the auxiliary stage is designed for high-frequency operation. A 50W, 48V-to-0.8V experimental prototype was built to validate the proposed architecture. Load transients from 5 A to 29 A were applied to the prototype, resulting in an output voltage deviation of 60 mV. The system achieves a peak efficiency of 89.5\% with an output capacitance of only 720 µF and an auxiliary capacitance of 120 µF.

	Adaptive Resonant-Valley Switching for a GaN HEMT Direct AC-AC Auxiliary Resonant Commutated Pole Converter By Kyle STEYN	[View] [Download]
Abstract: Zero-voltage zero-current switching is not guaranteed with auxiliary resonant commutated pole (ARCP) based topologies. The optimal dead-time is dependant on various parameters and cannot easily be calculated in real-time. A control technique that ensures all phase-arm switches turn on during the first resonant valley is presented. The voltage across one phase-arm switch is sampled during a turn-on transition and stored. The samples are processed by an adaptive zero-crossing algorithm and the optimal dead-time for the next switching cycle is predicted. The proposed technique was validated during a load transient and at steady-state in simulation and experimentally on a 5-kW direct ac-ac ARCP prototype.

	Experimental Demonstration of a 2.2kW Active-Clamp Converter for High-Current Wide-Voltage-Transfer Ratio Applications By Philipp REHLAENDER	[View] [Download]
Abstract: Active-clamp forward converters are typically not applied for converters with power ratings larger than 500 W as power as the power transfer between primary and secondary is discontinuous leading to large magnetic components. This paper, however, proves that silicon carbide (SiC) devices enable this topology as a well-suitable topology for a wide voltage-transfer ratio due to the low switching losses allowing high switching frequencies reducing the size of the magnetic components. A laboratory prototype is designed using a very precise model. It employs SiC MOSFETs of 900 V for the primary and Si synchronous rectifiers of 100 V. The semiconductors are cooled with cost-efficient copper inlays, which effectiveness is demonstrated through a thermal FEM simulation. The developed prototype achieves a maximum efficiency of 95 \% while maintaining an efficiency above 92 \% for almost the entire operating region. The high efficiency and the power density of approximately 2 kW/l confirm the proposed concept. Finally, the converter is benchmarked to two LLC resonant converters (Si, SiC) and the prototype is used to verify a highly accurate steady-state model showing errors below 1 \%.