EPE Association: EPE 2007 - Subtopic 01-4 - DS: MOS controlled silicon power devices I

EPE 2007 - Subtopic 01-4 - DS: MOS controlled silicon power devices I
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2007 - Conference > EPE 2007 - Topic 01: 'Active devices' > EPE 2007 - Subtopic 01-4 - DS: MOS controlled silicon power devices I

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   A novel technique to reduce reverse recovery charge of a power diode
By SHAMMAS Noel [View]
[Download]

Abstract: Power diodes are required to have short reverse recovery time, soft recovery, high breakdown voltage and a low forward voltage drop at the rated forward current. Manufactures introduce recombination centres in the device to achieve these parameters; however, a trade-off between the on-state losses and breakdown voltages, and a trade-off between the on-state losses and switching speeds is still significant. In this paper, a post manufacturing technique that reduces the reverse recovery charge of a power diode is proposed. The reverse recovery characteristic of the power diode was simulated by reconstructing a test circuit similar to the one previously published. To implement the technique, a current injection circuit, which injects an additional current from a pre-charged capacitor into the power diode prior to current zero, was added into the test circuit with results indicating a significant reduction in the power diodes reverse recovery charge. This helps to cancel the reverse current due to the stored electronic charge in the wide drift region and therefore prevents the device from conducting large reverse current. Nevertheless, the technique requires precise timing for injecting the appropriate forward current pulse seeing that premature injection will increase the forward current, and belated injection will either lengthen the power diodes forward conduction period or switch the already turned off diode into its low impedance state. Two methods were developed to detect the falling anode current. The first method uses a digital signal processing (DSP) kit to predict the time where the falling anode current reaches zero based on its average gradient. The second method uses an analogue circuit to trigger the current injection circuit at a reference current level. Of the two methods, the DSP kit is limited by the processors response time; and the analogue circuit is restricted by its inability of predicting current zero. Therefore, the limiting factor of this technique is the electronic delay in its components.

   Comparative Evaluation of IGCT and GTO Thyristor for series connection in high power voltage source inverter based FACTS applications
By BHATTACHARYA Subhashish [View]
[Download]

Abstract: In this paper, comparative evaluation between 4.5 kV, 4 kA GTO thyristor and IGCT for series connection in high power three-level Neutral Point Clamped (NPC) voltage source inverter applications is reported. Turn-off tests for GTO and IGCT are compared with RCD snubber at high dc voltage and current. Small RC snubber design is optimized and series connection issues for IGCT are addressed. Experimental results are compared for a two three-level NPC inverter poles operated as H-bridge with three series connected 4.5kV, 4kA GTO Thyristors and IGCTs per switch.

   Deep Trench MOSFET structures study for a 1200 Volts application
By ISOIRD Karine; ROIG Jaume; DUBREUIL Pascal; THEOLIER L.; MORANCHO Frederic; BRUNET Magali; MAHFOZ-KOTB Hicham [View]
[Download]

Abstract: In this work we studied some possible high voltage MOSFETs structures that can replace the IGBT in the railway traction converters. In this purpose, some high voltage power MOS structures are presented and theoretically compared using 2D simulations. Simulations results show that the DT-UMOSFET should be a good challenger to the 1200 Volts IGBT. Moreover, the influence of various parameters, like trench width, trench verticality or boron dose, on DT-UMOSFET static performances is shown.

   Novel Voltage Balancing Technique For Series Connection of IGBTs
By WITHANAGE Ruchira; SHAMMAS Noel [View]
[Download]

Abstract: For high power electronics applications, high voltage switches are realised by connecting existing devices in series. The main problem of unequal sharing of voltage across the series connected devices can be minimised by using active gate control techniques, snubber circuits and active clamping circuits. The aim of this paper is to present a novel hybrid voltage balancing technique which can achieve good voltage balancing with minimum number of components and minimum total losses (i.e. IGBT losses and balancing circuit losses). This technique minimises the disadvantages in present voltage balancing techniques and it consists of both an active voltage clamp circuit and an optimised passive snubber. The passive snubber capacitance is optimised to have low power losses. The proposed technique was validated by both simulation and experimental work. In simulation, two 1kV/50A IGBTs were connected in series and the results showed good voltage balancing with minimum losses. The experimental work was carried out on three 3.3kV/1200A IGBTs connected in series. Experimental results showed good voltage balancing across the devices and the possibility of finding an optimum capacitance. Determining of the optimum snubber capacitance is critical in the hybrid voltage balancing technique and the dependence of the optimum capacitance on load is discussed.

   Recent developments in IGCT gate units
By LUESCHER Matthias; BACKLUND Bjoern [View]
[Download]

Abstract: Recent improvements in GCT silicon design have allowed increased turn-off capabilities for IGCTs thus placing greater demands on the gate-unit. This paper shows how the design challenges arising from this new turn-off capability have been addressed to re-establish a balance between the semiconductor and the gate unit for optimal IGCT performance.

   Regenerative Turn-off Power Devices
By SILBER Dieter; ROSENSAFT Boris; VEMULAPATI Umamaheswara Reddy [View]
[Download]

Abstract: We describe the operation and application of a new class of power devices which have regenerative turn-off capability. The presented regenerative turn-off devices are (1) circuit beaker (2) safe controlled power switch and (3) regenerative diode. Regenerative turn-off devices are conceptually dual to regenerative turn-on devices like the shockley diodes or thyristor type devices. Regenerative turn-off devices are normally ON and enable current flow until a certain current/voltage level above which the regenerative turn-off action starts. Therefore, they can be developed as circuit breakers, safe controlled power switches and regenerative diodes. Regenerative diodes are normally open and block at small reverse current/voltage levels [1]. Regenerative turn-off devices can be realized from a series connection of normally ON type JFETs which are connected as controlled source ballasts. Full gate controlled device (safe controlled power switch) can be obtained with the addition of MOS gates to the circuit breaker. High injection (thyristor) versions of the circuit breaker and safe controlled power switch can be developed and they exhibit good plasma concentration which is comparable to that of the advanced IGBTs [2]. Regenerative diode can also be developed from the basic structure of a Dual Thyristor which has a low or neglectable threshold voltage and closes at reverse polarity. Regenerative diode is superior compared to schottky diodes and junction barrier controlled schottky (JBS) rectifier both in forward and reverse directions [1], but of course, requires a more complicated technology. JBS rectifiers are obtained with a good compromise between p-n and schottky diodes [3]. Though regenerative diode has inferior on-state behavior when compared to that of the synchronous rectifier, it does not require any external triggering.

   Robustness and turn-off losses of high voltage IGBT
By ECKEL Hans-Guenter; BAKRAN Mark M. [View]
[Download]

Abstract: A simple model for the turn-off of high voltage IGBTs with long carrier lifetime is derived from the device physics. It is used to get a better understanding of the behavior of the device during the turn-off transient and the influence of the gate drive and a capacitive snubber. The peak electric field and the overvoltage are analyzed and special effects of field stop devices are discussed.

   Silicon Carbide (SiC) D-MOS for Grid-Feeding Solar-Inverters
By STALTER Olivier; BURGER Bruno [View]
[Download]

Abstract: The new MOSFET-generation with SiC-materials seems well suited for power electronics converters up to 1200 V operating-voltage, and particularly for grid-feeding solar-inverters. Their high switching speed and low on-resistance RDS(on) allow the use of higher switching frequencies, which could mainly reduce the costs and weight of the converters. This paper shows a comparison between IGBT and SiC DMOSFET devices and first measurements of some 1200 V SiC DMOSFET samples.

   Simulation based analysis of a monolithically integrated fast and slow IGBT structure
By DE MAGLIE Rodolphe [View]
[Download]

Abstract: This paper presents an analysis of a monolithic integrated structure dedicated to improve the trade off between switching and conduction losses. This structure is achieved by connecting two IGBT in parallel. A fast IGBT is dedicated to the conduction mode and a slow IGBT for the switching operation. After a brief reminder of the device operating principle, physical simulations of a discrete association have been performed in order to carry out an analysis of the performance. So, the losses have been evaluated for different switching frequencies, duty cycles and IGBT configurations. Two strategies of simple gates drivers are also briefly described. First experimental results of an integrated structure are presented and compared to analytical simulation results. Furthermore, to gain an insight into the device internal carrier distribution during the two operating phases (conducting and switching operation), [2D] simulations were carried out. These last simulations explained the difference between the experimental and simulations results.

   SMIS - a prospective solution for power MOSFET transistor
By PODGORSKI Jacek; LISIK Zbigniew; SZMIDT Jan [View]
[Download]

Abstract: The new solution of unipolar device, called SMIS, that can offer some advantages in the field of power semiconductor devices is presented. Correctness of the SMIS concept with reference to its application to power unipolar transistors has been checked by numerical simulations and manufacturing of test structures. The results of these investigations are presented in paper.

   THERMAL RUNAWAY EVALUATION FOR HIGH TEMPERATURE TRIACS
By GONTHIER Laurent; JACQUES Sebastien; BATUT Nathalie [View]
[Download]

Abstract: This paper deals with thermal runaway that could occur for the new high-temperature TRIACs which are used with junction temperatures up to 160C in transient state. The conditions to avoid thermal runaway for the specific case of alternative voltage are discussed. Experimental measurements are given and compared with a theoretical analysis.

EPE 2007 - Subtopic 01-4 - DS: MOS controlled silicon power devices I
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2007 - Conference > EPE 2007 - Topic 01: 'Active devices' > EPE 2007 - Subtopic 01-4 - DS: MOS controlled silicon power devices I
	[return to parent folder]

	A novel technique to reduce reverse recovery charge of a power diode By SHAMMAS Noel	[View] [Download]
Abstract: Power diodes are required to have short reverse recovery time, soft recovery, high breakdown voltage and a low forward voltage drop at the rated forward current. Manufactures introduce recombination centres in the device to achieve these parameters; however, a trade-off between the on-state losses and breakdown voltages, and a trade-off between the on-state losses and switching speeds is still significant. In this paper, a post manufacturing technique that reduces the reverse recovery charge of a power diode is proposed. The reverse recovery characteristic of the power diode was simulated by reconstructing a test circuit similar to the one previously published. To implement the technique, a current injection circuit, which injects an additional current from a pre-charged capacitor into the power diode prior to current zero, was added into the test circuit with results indicating a significant reduction in the power diodes reverse recovery charge. This helps to cancel the reverse current due to the stored electronic charge in the wide drift region and therefore prevents the device from conducting large reverse current. Nevertheless, the technique requires precise timing for injecting the appropriate forward current pulse seeing that premature injection will increase the forward current, and belated injection will either lengthen the power diodes forward conduction period or switch the already turned off diode into its low impedance state. Two methods were developed to detect the falling anode current. The first method uses a digital signal processing (DSP) kit to predict the time where the falling anode current reaches zero based on its average gradient. The second method uses an analogue circuit to trigger the current injection circuit at a reference current level. Of the two methods, the DSP kit is limited by the processors response time; and the analogue circuit is restricted by its inability of predicting current zero. Therefore, the limiting factor of this technique is the electronic delay in its components.

	Comparative Evaluation of IGCT and GTO Thyristor for series connection in high power voltage source inverter based FACTS applications By BHATTACHARYA Subhashish	[View] [Download]
Abstract: In this paper, comparative evaluation between 4.5 kV, 4 kA GTO thyristor and IGCT for series connection in high power three-level Neutral Point Clamped (NPC) voltage source inverter applications is reported. Turn-off tests for GTO and IGCT are compared with RCD snubber at high dc voltage and current. Small RC snubber design is optimized and series connection issues for IGCT are addressed. Experimental results are compared for a two three-level NPC inverter poles operated as H-bridge with three series connected 4.5kV, 4kA GTO Thyristors and IGCTs per switch.

	Deep Trench MOSFET structures study for a 1200 Volts application By ISOIRD Karine; ROIG Jaume; DUBREUIL Pascal; THEOLIER L.; MORANCHO Frederic; BRUNET Magali; MAHFOZ-KOTB Hicham	[View] [Download]
Abstract: In this work we studied some possible high voltage MOSFETs structures that can replace the IGBT in the railway traction converters. In this purpose, some high voltage power MOS structures are presented and theoretically compared using 2D simulations. Simulations results show that the DT-UMOSFET should be a good challenger to the 1200 Volts IGBT. Moreover, the influence of various parameters, like trench width, trench verticality or boron dose, on DT-UMOSFET static performances is shown.

	Novel Voltage Balancing Technique For Series Connection of IGBTs By WITHANAGE Ruchira; SHAMMAS Noel	[View] [Download]
Abstract: For high power electronics applications, high voltage switches are realised by connecting existing devices in series. The main problem of unequal sharing of voltage across the series connected devices can be minimised by using active gate control techniques, snubber circuits and active clamping circuits. The aim of this paper is to present a novel hybrid voltage balancing technique which can achieve good voltage balancing with minimum number of components and minimum total losses (i.e. IGBT losses and balancing circuit losses). This technique minimises the disadvantages in present voltage balancing techniques and it consists of both an active voltage clamp circuit and an optimised passive snubber. The passive snubber capacitance is optimised to have low power losses. The proposed technique was validated by both simulation and experimental work. In simulation, two 1kV/50A IGBTs were connected in series and the results showed good voltage balancing with minimum losses. The experimental work was carried out on three 3.3kV/1200A IGBTs connected in series. Experimental results showed good voltage balancing across the devices and the possibility of finding an optimum capacitance. Determining of the optimum snubber capacitance is critical in the hybrid voltage balancing technique and the dependence of the optimum capacitance on load is discussed.

	Recent developments in IGCT gate units By LUESCHER Matthias; BACKLUND Bjoern	[View] [Download]
Abstract: Recent improvements in GCT silicon design have allowed increased turn-off capabilities for IGCTs thus placing greater demands on the gate-unit. This paper shows how the design challenges arising from this new turn-off capability have been addressed to re-establish a balance between the semiconductor and the gate unit for optimal IGCT performance.

	Regenerative Turn-off Power Devices By SILBER Dieter; ROSENSAFT Boris; VEMULAPATI Umamaheswara Reddy	[View] [Download]
Abstract: We describe the operation and application of a new class of power devices which have regenerative turn-off capability. The presented regenerative turn-off devices are (1) circuit beaker (2) safe controlled power switch and (3) regenerative diode. Regenerative turn-off devices are conceptually dual to regenerative turn-on devices like the shockley diodes or thyristor type devices. Regenerative turn-off devices are normally ON and enable current flow until a certain current/voltage level above which the regenerative turn-off action starts. Therefore, they can be developed as circuit breakers, safe controlled power switches and regenerative diodes. Regenerative diodes are normally open and block at small reverse current/voltage levels [1]. Regenerative turn-off devices can be realized from a series connection of normally ON type JFETs which are connected as controlled source ballasts. Full gate controlled device (safe controlled power switch) can be obtained with the addition of MOS gates to the circuit breaker. High injection (thyristor) versions of the circuit breaker and safe controlled power switch can be developed and they exhibit good plasma concentration which is comparable to that of the advanced IGBTs [2]. Regenerative diode can also be developed from the basic structure of a Dual Thyristor which has a low or neglectable threshold voltage and closes at reverse polarity. Regenerative diode is superior compared to schottky diodes and junction barrier controlled schottky (JBS) rectifier both in forward and reverse directions [1], but of course, requires a more complicated technology. JBS rectifiers are obtained with a good compromise between p-n and schottky diodes [3]. Though regenerative diode has inferior on-state behavior when compared to that of the synchronous rectifier, it does not require any external triggering.

	Robustness and turn-off losses of high voltage IGBT By ECKEL Hans-Guenter; BAKRAN Mark M.	[View] [Download]
Abstract: A simple model for the turn-off of high voltage IGBTs with long carrier lifetime is derived from the device physics. It is used to get a better understanding of the behavior of the device during the turn-off transient and the influence of the gate drive and a capacitive snubber. The peak electric field and the overvoltage are analyzed and special effects of field stop devices are discussed.

	Silicon Carbide (SiC) D-MOS for Grid-Feeding Solar-Inverters By STALTER Olivier; BURGER Bruno	[View] [Download]
Abstract: The new MOSFET-generation with SiC-materials seems well suited for power electronics converters up to 1200 V operating-voltage, and particularly for grid-feeding solar-inverters. Their high switching speed and low on-resistance RDS(on) allow the use of higher switching frequencies, which could mainly reduce the costs and weight of the converters. This paper shows a comparison between IGBT and SiC DMOSFET devices and first measurements of some 1200 V SiC DMOSFET samples.

	Simulation based analysis of a monolithically integrated fast and slow IGBT structure By DE MAGLIE Rodolphe	[View] [Download]
Abstract: This paper presents an analysis of a monolithic integrated structure dedicated to improve the trade off between switching and conduction losses. This structure is achieved by connecting two IGBT in parallel. A fast IGBT is dedicated to the conduction mode and a slow IGBT for the switching operation. After a brief reminder of the device operating principle, physical simulations of a discrete association have been performed in order to carry out an analysis of the performance. So, the losses have been evaluated for different switching frequencies, duty cycles and IGBT configurations. Two strategies of simple gates drivers are also briefly described. First experimental results of an integrated structure are presented and compared to analytical simulation results. Furthermore, to gain an insight into the device internal carrier distribution during the two operating phases (conducting and switching operation), [2D] simulations were carried out. These last simulations explained the difference between the experimental and simulations results.

	SMIS - a prospective solution for power MOSFET transistor By PODGORSKI Jacek; LISIK Zbigniew; SZMIDT Jan	[View] [Download]
Abstract: The new solution of unipolar device, called SMIS, that can offer some advantages in the field of power semiconductor devices is presented. Correctness of the SMIS concept with reference to its application to power unipolar transistors has been checked by numerical simulations and manufacturing of test structures. The results of these investigations are presented in paper.

	THERMAL RUNAWAY EVALUATION FOR HIGH TEMPERATURE TRIACS By GONTHIER Laurent; JACQUES Sebastien; BATUT Nathalie	[View] [Download]
Abstract: This paper deals with thermal runaway that could occur for the new high-temperature TRIACs which are used with junction temperatures up to 160C in transient state. The conditions to avoid thermal runaway for the specific case of alternative voltage are discussed. Experimental measurements are given and compared with a theoretical analysis.