This paper presents a performance comparison between switching and reduced-order models of grid-f... more This paper presents a performance comparison between switching and reduced-order models of grid-following inverters. Different models have been developed to study the inverter’s operation using MATLAB and PSIM simulation tools. These models offer a tradeoff between accuracy and computational burden. The switching model fully represents the discontinuities in the inverter due to switching, but such a model demands high computational resources. The inverter representation is simplified using reduced-order models, which is common in the literature. However, the fidelity of these simplified models might not be adequate for some applications. Therefore, it is essential to investigate the performance of such models closely to ensure their suitability depending on the purpose of the analysis. Hence, a comparative study between switching and reduced-order models is presented here by simulating different scenarios and operation conditions. The results have validated the efficacy of the reduc...
International Conference on Performance Engineering, May 1, 2011
Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present ... more Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present results of dynamic characterization of these devices. A standard double pulse test with clamped inductive load was used during this characterization. Switching times are registered and energy losses are calculated. The impact of driver circuitry on device performance is highlighted. A comparison between commercially available driver and an optimized driver is established here showing the dependency of switching losses of this device on driver circuit. When an optimized driver is used, a reduction of 80% and 70% in turn-off time and switching loss is observed, respectively.
ABSTRACT Testing and verifying new design ideas for power electronic systems by simulations rely ... more ABSTRACT Testing and verifying new design ideas for power electronic systems by simulations rely on accuracy of device models. For SiC-based devices, lack of reliable models that accurately describe device performance at different temperatures is noticed. Models are either complex and requiring detailed device structure or isothermal without temperature dependency. In this paper simple power rectifier models for use by power electronics application engineers with wide temperature range are represented. This work benefits from the available models in literature and extends their soundness to a temperature range at which SiC devices are expected to function. Simulation results of forward conduction characteristics were compared with measurement results to check the credibility of used models.
Power electronic devices are the most important element in any power electronic system. In the la... more Power electronic devices are the most important element in any power electronic system. In the last decade, silicon carbide-based devices have emerged as an alternative to silicon-based devices promising a new era in power conversion. The focus of many studies has been on improving material technologies to reduce production cost and defect density. This development has produced devices with superior characteristics. However, the unique properties of silicon carbide favour the development of relatively new power devices, such as the enhanced-mode junction field-effect transistor, in order to exploit the full potential of the material. Following the introduction of such devices, power electronics engineers face new challenges.In this thesis, the characteristics of SiC power devices, including the PiN diode, the Schottky diode and the JFET, are investigated. Simplified behavioural models for these SiC devices are established and implemented in commercial circuit simulators. The work focuses on the SiC enhancement-mode power VJFET as it is a potential candidate to replace Si MOSFETs and IGBTs especially for medium voltage applications.Breakdown voltage and drift region design of the SiC PiN diode are studied. Due to the conductivity modulation in the drift region, the PiN diode achieves low on-resistance. At the same time, the high critical electric field of SiC allows high breakdown voltage. However, a saturation voltage of approximately 3 V appears during the forward condition mode as a result of the wide bandgap of SiC. The high forward voltage leads to more conduction loss making this type of diodes only attractive for high voltage applications where the voltage drop over a Schottky diode with same breakdown voltage becomes prohibitively high. The characteristic and the modelling of both PiN and Schottky diodes are discussed in this thesis. Suggested models are implemented in commercial circuit simulators and feature a satisfactory accuracy over a wide temperature range.By studying the SiC VJFET structure, the physics of the device and gate drive requirements are investigated. Several driving technologies are tested. However, for an effective driving, employing a two-stage driver is recommended. With this driver, high switching speeds are achievable with minimal switching energy loss. Using the SiC JFET, a high efficiency energy conversion, that combines low switching losses with low conduction loss, is possible.Finally, a model for SiC VJFET is established and implemented on LTSpice. Model parameters are determined by measurements and datasheet values. There is a good agreement between simulation results using this model and measured static and dynamic characteristics of the SiC VJFET.
This paper proposes a high-efficiency and dimmable current sink topology along with a design meth... more This paper proposes a high-efficiency and dimmable current sink topology along with a design methodology for low node processes. The design methodology is demonstrated using a boost-based WLED driver application. In this work, the focus is on current regulation rather than voltage regulation. Therefore, the proposed topology exploits a smaller and faster NMOS pass device, replacing the conventional PMOS-based LDO arrangement. An amplifier-boosted pass-transistor current sink topology combined with a 5-bit programmable degenerated source resistor is being utilized for high-efficiency and brightness control. The realized WLED driver validates the proposed topology and the design methodology utilizing 40 nm CMOS TSMC technology. The design takes advantage of the programmability of the resistor to enhance the system’s power efficiency. This programmable resistor enables dimmability via current segmentation with a 1 mA step for a total of 25 mA. For a 500 mV voltage ripple at the DC-DC c...
2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021
This paper describes the design of a dual active bridge (DAB) DC-DC converter for DC microgrid ap... more This paper describes the design of a dual active bridge (DAB) DC-DC converter for DC microgrid applications. The converter is utilized to interface a battery storage system with the DC microgrid. A control scheme that allows the converter to charge a lithium-ion battery using different charging protocols is demonstrated. Moreover, the bidirectional power flow capability of the converter is verified. The designed converter is simulated using PSIM and several operational scenarios are studied.
Journal of Low Power Electronics and Applications, 2022
This work presents various essential features and design aspects of a single-inductor, common-out... more This work presents various essential features and design aspects of a single-inductor, common-output, and multi-string White Light Emitting Diode (WLED) driver for low-power portable devices. High efficiency is one of the main features of such a device. Here, the efficiency improvement is achieved by selecting the proper arrangement of WLEDs and a proper sensing-circuit technique to determine the minimum, real-time, needed output voltage. This minimum voltage necessary to activate all WLEDs depends on the number of strings and the forward voltage drops among the WLEDs. Advanced CMOS technology is advantageous in mixed-signal environments such as WLED drivers. However, this process suffers from low on-resistance, which degrades the accuracy of the current sinks. To accommodate the above features and mitigate the low node process issue, a boost-converter that is single output with a load of a three-string arrangement, with 6 WLEDs each, is presented. The designed driver has an input v...
Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present ... more Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present results of dynamic characterization of these devices. A standard double pulse test with clamped inductive load was used during this characterization. Switching times are registered and energy losses are calculated. The impact of driver circuitry on device performance is highlighted. A comparison between commercially available driver and an optimized driver is established here showing the dependency of switching losses of this device on driver circuit. When an optimized driver is used, a reduction of 80% and 70% in turn-off time and switching loss is observed, respectively.
Journal of Low Power Electronics and Applications, 2021
In this work, a multi-independent-output, multi-string, high-efficiency, boost-converter-based wh... more In this work, a multi-independent-output, multi-string, high-efficiency, boost-converter-based white LED (WLED) driver architecture is proposed. It utilizes a single inductor main switch with a common maximum duty cycle controller (MDCC) in the feedback loop. A simple pulse skipping controller (PSC) is utilized in each high-side switch of the multiple independent outputs. Despite the presence of multiple independent outputs, a single over-voltage protection (OVP) circuit is used at the output to protect the circuit from any voltage above 27 V. An open circuit in any of the strings is addressed, in addition to the LED’s short-circuit conditions. Excellent current matching between strings is achieved, despite the low ON-resistance (Rdson) of transistors used in the 40 nm process. Most circuits are designed in digital CMOS logic to overcome the extreme process variations in the 40 nm node. Compared to a single output parallel strings topology, a 50% improvement in efficiency is achieve...
This paper presents a performance comparison between switching and reduced-order models of grid-f... more This paper presents a performance comparison between switching and reduced-order models of grid-following inverters. Different models have been developed to study the inverter’s operation using MATLAB and PSIM simulation tools. These models offer a tradeoff between accuracy and computational burden. The switching model fully represents the discontinuities in the inverter due to switching, but such a model demands high computational resources. The inverter representation is simplified using reduced-order models, which is common in the literature. However, the fidelity of these simplified models might not be adequate for some applications. Therefore, it is essential to investigate the performance of such models closely to ensure their suitability depending on the purpose of the analysis. Hence, a comparative study between switching and reduced-order models is presented here by simulating different scenarios and operation conditions. The results have validated the efficacy of the reduc...
International Conference on Performance Engineering, May 1, 2011
Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present ... more Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present results of dynamic characterization of these devices. A standard double pulse test with clamped inductive load was used during this characterization. Switching times are registered and energy losses are calculated. The impact of driver circuitry on device performance is highlighted. A comparison between commercially available driver and an optimized driver is established here showing the dependency of switching losses of this device on driver circuit. When an optimized driver is used, a reduction of 80% and 70% in turn-off time and switching loss is observed, respectively.
ABSTRACT Testing and verifying new design ideas for power electronic systems by simulations rely ... more ABSTRACT Testing and verifying new design ideas for power electronic systems by simulations rely on accuracy of device models. For SiC-based devices, lack of reliable models that accurately describe device performance at different temperatures is noticed. Models are either complex and requiring detailed device structure or isothermal without temperature dependency. In this paper simple power rectifier models for use by power electronics application engineers with wide temperature range are represented. This work benefits from the available models in literature and extends their soundness to a temperature range at which SiC devices are expected to function. Simulation results of forward conduction characteristics were compared with measurement results to check the credibility of used models.
Power electronic devices are the most important element in any power electronic system. In the la... more Power electronic devices are the most important element in any power electronic system. In the last decade, silicon carbide-based devices have emerged as an alternative to silicon-based devices promising a new era in power conversion. The focus of many studies has been on improving material technologies to reduce production cost and defect density. This development has produced devices with superior characteristics. However, the unique properties of silicon carbide favour the development of relatively new power devices, such as the enhanced-mode junction field-effect transistor, in order to exploit the full potential of the material. Following the introduction of such devices, power electronics engineers face new challenges.In this thesis, the characteristics of SiC power devices, including the PiN diode, the Schottky diode and the JFET, are investigated. Simplified behavioural models for these SiC devices are established and implemented in commercial circuit simulators. The work focuses on the SiC enhancement-mode power VJFET as it is a potential candidate to replace Si MOSFETs and IGBTs especially for medium voltage applications.Breakdown voltage and drift region design of the SiC PiN diode are studied. Due to the conductivity modulation in the drift region, the PiN diode achieves low on-resistance. At the same time, the high critical electric field of SiC allows high breakdown voltage. However, a saturation voltage of approximately 3 V appears during the forward condition mode as a result of the wide bandgap of SiC. The high forward voltage leads to more conduction loss making this type of diodes only attractive for high voltage applications where the voltage drop over a Schottky diode with same breakdown voltage becomes prohibitively high. The characteristic and the modelling of both PiN and Schottky diodes are discussed in this thesis. Suggested models are implemented in commercial circuit simulators and feature a satisfactory accuracy over a wide temperature range.By studying the SiC VJFET structure, the physics of the device and gate drive requirements are investigated. Several driving technologies are tested. However, for an effective driving, employing a two-stage driver is recommended. With this driver, high switching speeds are achievable with minimal switching energy loss. Using the SiC JFET, a high efficiency energy conversion, that combines low switching losses with low conduction loss, is possible.Finally, a model for SiC VJFET is established and implemented on LTSpice. Model parameters are determined by measurements and datasheet values. There is a good agreement between simulation results using this model and measured static and dynamic characteristics of the SiC VJFET.
This paper proposes a high-efficiency and dimmable current sink topology along with a design meth... more This paper proposes a high-efficiency and dimmable current sink topology along with a design methodology for low node processes. The design methodology is demonstrated using a boost-based WLED driver application. In this work, the focus is on current regulation rather than voltage regulation. Therefore, the proposed topology exploits a smaller and faster NMOS pass device, replacing the conventional PMOS-based LDO arrangement. An amplifier-boosted pass-transistor current sink topology combined with a 5-bit programmable degenerated source resistor is being utilized for high-efficiency and brightness control. The realized WLED driver validates the proposed topology and the design methodology utilizing 40 nm CMOS TSMC technology. The design takes advantage of the programmability of the resistor to enhance the system’s power efficiency. This programmable resistor enables dimmability via current segmentation with a 1 mA step for a total of 25 mA. For a 500 mV voltage ripple at the DC-DC c...
2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021
This paper describes the design of a dual active bridge (DAB) DC-DC converter for DC microgrid ap... more This paper describes the design of a dual active bridge (DAB) DC-DC converter for DC microgrid applications. The converter is utilized to interface a battery storage system with the DC microgrid. A control scheme that allows the converter to charge a lithium-ion battery using different charging protocols is demonstrated. Moreover, the bidirectional power flow capability of the converter is verified. The designed converter is simulated using PSIM and several operational scenarios are studied.
Journal of Low Power Electronics and Applications, 2022
This work presents various essential features and design aspects of a single-inductor, common-out... more This work presents various essential features and design aspects of a single-inductor, common-output, and multi-string White Light Emitting Diode (WLED) driver for low-power portable devices. High efficiency is one of the main features of such a device. Here, the efficiency improvement is achieved by selecting the proper arrangement of WLEDs and a proper sensing-circuit technique to determine the minimum, real-time, needed output voltage. This minimum voltage necessary to activate all WLEDs depends on the number of strings and the forward voltage drops among the WLEDs. Advanced CMOS technology is advantageous in mixed-signal environments such as WLED drivers. However, this process suffers from low on-resistance, which degrades the accuracy of the current sinks. To accommodate the above features and mitigate the low node process issue, a boost-converter that is single output with a load of a three-string arrangement, with 6 WLEDs each, is presented. The designed driver has an input v...
Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present ... more Enhancement-mode high voltage SiC VJFETs are available on market today. In this paper we present results of dynamic characterization of these devices. A standard double pulse test with clamped inductive load was used during this characterization. Switching times are registered and energy losses are calculated. The impact of driver circuitry on device performance is highlighted. A comparison between commercially available driver and an optimized driver is established here showing the dependency of switching losses of this device on driver circuit. When an optimized driver is used, a reduction of 80% and 70% in turn-off time and switching loss is observed, respectively.
Journal of Low Power Electronics and Applications, 2021
In this work, a multi-independent-output, multi-string, high-efficiency, boost-converter-based wh... more In this work, a multi-independent-output, multi-string, high-efficiency, boost-converter-based white LED (WLED) driver architecture is proposed. It utilizes a single inductor main switch with a common maximum duty cycle controller (MDCC) in the feedback loop. A simple pulse skipping controller (PSC) is utilized in each high-side switch of the multiple independent outputs. Despite the presence of multiple independent outputs, a single over-voltage protection (OVP) circuit is used at the output to protect the circuit from any voltage above 27 V. An open circuit in any of the strings is addressed, in addition to the LED’s short-circuit conditions. Excellent current matching between strings is achieved, despite the low ON-resistance (Rdson) of transistors used in the 40 nm process. Most circuits are designed in digital CMOS logic to overcome the extreme process variations in the 40 nm node. Compared to a single output parallel strings topology, a 50% improvement in efficiency is achieve...
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