EPE Association: EPE 1989 - 28 - Dialogue Session 1.1: FAST SWITCHING DEVICES

EPE 1989 - 28 - Dialogue Session 1.1: FAST SWITCHING DEVICES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 28 - Dialogue Session 1.1: FAST SWITCHING DEVICES

   [return to parent folder]

   CHARGE CONTROL TRANSIENT MODELLING OF ASYMMETRICAL PIN POWER DIODES
By J. McGhee; I. A. Henderson [View]
[Download]

Abstract: A charge control transient model for asymmetrical PIN semiconductor power diodes is derived. This model is embodied in a non-linear ordinary differential equation of first order. It is shown that effective charge control modelling requires a knowledge of the excess charge stored, the current at the ohmic contact with the external world and that at the space-charge to bulk boundary on the P side of the PI junction. They must be specified in terms of carrier densities at the respective boundaries and external drive current. Expressing both carrier currents at the PI junction using correction factors reveals how all asymmetries influence the open circuit voltage decay of these diodes. In this manner account is taken of end region recombination due to space charge recombination, finite geometry, and enhanced recombination due to ambipolar effects. The model is compared with a long emitter diffusion model and a low level charge control model.

   A UNIFIED MODEL FOR THE POWER MOSFET INCLUDING THE INVERSE DIODE AND THE PARASITIC BIPOLAR TRANSISTOR
By C. H. Xu; D. Schröder [View]
[Download]

Abstract: The power MOSFET with the inverse diode and the parasitic bipolar transistor is analyzed and characterized through modelling and simulation. The models for the MOSFET switch and the power diode developed by the authors and a conventional bipolar transistor model are combined with each other and unified to a complete model for the power MOSFET. It describes beside the charaderistics of each single model also the interaction between them. The model is implemented in the commercially available netwerk simulator IG-SPICE (an enhanced SPICE program) by writing a "state-dependent Fortran subprogram". Complicated dynamic behavior of the whole device in circuits for instance a bridge circuit can he simulated and analyzed, where the device is used as a switch as well as a free-wheeling diode and the parasitic bipolar transistor can be activated. The simulation shows a good agreement with the measurement.

   SMART PROTECTION OF A POWERMOSFET INVERTER BRIDGE
By G. Debuf; J. Pollefliet [View]
[Download]

Abstract: A bridge converter is as reliable as his protection. Conventional methods of protection reach their limit by increasing frequency. This paper presents a practical solution for a "dynamic" protection circuit. It is an application on a threephase inverter with powermosfets (BUZ80A Siemens) for the PWM-drive of a 1kW induction motor. Our philosophy consists in watching the actual situation of the switch (on, off, short-circuited) and to use this information to control the conduction of the other mosfets. The presented principles are of course also applicable for inverters with bipolar transistors whatever the switched power.

   INFLUENCE OF PARASITIC EFFECTS ON THE SWITCHING AND COMMUTATION BEHAVlOR OF FAST POWER SEMICONDUCTOR DEVICES
By G. Schulze; H. Stut; L. lorenz [View]
[Download]

Abstract: The aim of this paper is to show how the individual dissipative components of a transistor half-bridge configuration can be measured and the efficiency of the various types of transistor evaluated. The way in which a power transistor can be optimized for high clock frequencies in conjunction with a free-wheeling diode is also elaborated. In addition to the consideration of the power losses of a power semiconductor device, the controllability of short circuits is of ever increasing importance. Electrical behavior in the event of a short circuit is discussed, taking an IGBT half-bridge configuration as an example. Finally the parasitic effects which are particularly likely to occur during fast switching of an IGBT are explained.

   THE RING-EMITTER TRANSISTOR - A 20 KHZ HIGH-CURRENT SWITCH FOR PWM INVERTER APPLICATIONS
By Samir F. Salama; Joachim Holtz [View]
[Download]

Abstract: The introduction of advanced microstructure technology in the fabrication of power semiconductor devices has created a new class of semiconductor switches with improved dynamic performance. The ring-emitter transistor SIRET is a product of the recent development in this area. This paper presents a study of the static characteristics and the dynamic switching performance of a half-bridge inverter built from a 50 A, 1000 V SIRET-Module. Owing to the special mechanical construction with minimized stray inductances, snubberless operation is possible at 20 kHz switching frequency. Special attention had to be given to thebase drive circuit as the switching performance of the device depends greatly on the base current waveform.

   MODELLING POWER MOSFET DC-DC CONVERTERS USING SPICE2 PROGRAM
By E. Tatakis; J. Sanchez-Molero [View]
[Download]

Abstract: This paper deals with computer-aided analysis and simulation of a power mosfet dc-dc converter. Improved models for power mosfets and power diodes, adapted to SPICE2 are described in order to simulate accurately their static and dynamic behavior. The parameters of the models are determined using non-linear optimization methods. The variation of power mosfets on-resistance with drain current is considered and the variable gate-drain capacitance is simulated by an auxiliary network. Hence its possible to estimate with an excellent accuracy turn-on and turn-off wave forms, as well as switching and conduction losses. Models for power diodes are based upon the physical structure of a PIN diode. An auxiliary network is used to simulate the rate of decrease of the recovery current which plays an important role in power circuits containing inductances . We also demonstrate that noise voltages at the output terminals of the switching power supply can be predicted if we include the dominant parasitic elements in the models of passive components. To obtain accurate values of these spikes we have to take the layout into account by introducing the inductances of the connections. Simulated wave forms on a forward dc-dc converter and experimental results are in excellent agreement.

   DESIGN OF A 3-PHASE, MOSFET INVERTER AND ASSOCIATED GATE-DRIVE CIRCUIT
By H. C. Lovatt; M. L. McClelland; M. J. Turner [View]
[Download]

Abstract: The paper discusses, with particular reference to the gate-drive circuit, the design of an inverter to reproduce a stored current waveform with a high degree of accuracy for use in a motor drive system. The gate-drive circuit combines low cost with individual overcurrent protection for each switch, thus providing shoot-through and short-circuit protection without the need or expense of a d.c. link choke. In addition to the gate-drive circuit design, the reasons for choosing MOSFETs as the main power devices, alternative gate-drive circuit configurations and inverter protection techniques are discussed. Although designed for a standard bridge configuration, MOSFET inverter, the gate-drive circuit presented is applicable to other MOS input devices and to other power circuit configurations.

   THE INSULATED GATE BIPOLAR TRANSISTOR: SWITCHING MODES
By J. P. Ferrieux; F. Forest; P. Lienart [View]
[Download]

Abstract: The I.G.B.T. (insulated gate bipolar transistor), a very attractive device, seems to be the switch of the future, in medium power range. But since it is a new component, its behaviour is misjudged in particular switching modes. Once recalled principal characteristics of I.G.B.T., this paper deals with different switching modes (thyristor, dual-thyristor) to which are associated new types of high-frequency converters. These modes seems to release the best use of the device, as its appears in experimental results. Yet, this work points out latch-up and stored charge problems, in thyristor configuration and then, the necessity to define precisely the I.G.B.T. limitations in this mode, in order to allow conception of high-performing and low-cost converters.

   EXTENDED EBERS - MOLL'S MODEL OF SCR
By W. Pietrenko [View]
[Download]

Abstract: The physical model of the SCR is proposed. The SCR as a one-dimensional pnpn structure is treated in the model. Some applications of the model are presented: the isothermal and nonisothermal D.C. characteristics of the modeled device, the computer simulation of the circuit with the SCR by SPICE and the short analysis of selected properties of the SCR.

   OVERCURRENT PROTECTION FOR POWER-MOSFETS
By Th. Kalker [View]
[Download]

Abstract: The excellent switching capabilities of power MOSFETs permit the design of voltage fed inverters operating at high switching frequencies. By the use of FREDFETs the power circuit is very simple as no additional diodes and special snubbers are required. To ensure a safe operation of the inverter the switches have to be protected from overcurrent. In this paper a method is proposed to limit the drain current by modifying the gate driver characteristic. As a result a simple MOSFET driver is presented, which performs an overcurrent protection even under a short circuit condition. Its performance is proved by experimental measurements.

EPE 1989 - 28 - Dialogue Session 1.1: FAST SWITCHING DEVICES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 28 - Dialogue Session 1.1: FAST SWITCHING DEVICES
	[return to parent folder]

	CHARGE CONTROL TRANSIENT MODELLING OF ASYMMETRICAL PIN POWER DIODES By J. McGhee; I. A. Henderson	[View] [Download]
Abstract: A charge control transient model for asymmetrical PIN semiconductor power diodes is derived. This model is embodied in a non-linear ordinary differential equation of first order. It is shown that effective charge control modelling requires a knowledge of the excess charge stored, the current at the ohmic contact with the external world and that at the space-charge to bulk boundary on the P side of the PI junction. They must be specified in terms of carrier densities at the respective boundaries and external drive current. Expressing both carrier currents at the PI junction using correction factors reveals how all asymmetries influence the open circuit voltage decay of these diodes. In this manner account is taken of end region recombination due to space charge recombination, finite geometry, and enhanced recombination due to ambipolar effects. The model is compared with a long emitter diffusion model and a low level charge control model.

	A UNIFIED MODEL FOR THE POWER MOSFET INCLUDING THE INVERSE DIODE AND THE PARASITIC BIPOLAR TRANSISTOR By C. H. Xu; D. Schröder	[View] [Download]
Abstract: The power MOSFET with the inverse diode and the parasitic bipolar transistor is analyzed and characterized through modelling and simulation. The models for the MOSFET switch and the power diode developed by the authors and a conventional bipolar transistor model are combined with each other and unified to a complete model for the power MOSFET. It describes beside the charaderistics of each single model also the interaction between them. The model is implemented in the commercially available netwerk simulator IG-SPICE (an enhanced SPICE program) by writing a "state-dependent Fortran subprogram". Complicated dynamic behavior of the whole device in circuits for instance a bridge circuit can he simulated and analyzed, where the device is used as a switch as well as a free-wheeling diode and the parasitic bipolar transistor can be activated. The simulation shows a good agreement with the measurement.

	SMART PROTECTION OF A POWERMOSFET INVERTER BRIDGE By G. Debuf; J. Pollefliet	[View] [Download]
Abstract: A bridge converter is as reliable as his protection. Conventional methods of protection reach their limit by increasing frequency. This paper presents a practical solution for a "dynamic" protection circuit. It is an application on a threephase inverter with powermosfets (BUZ80A Siemens) for the PWM-drive of a 1kW induction motor. Our philosophy consists in watching the actual situation of the switch (on, off, short-circuited) and to use this information to control the conduction of the other mosfets. The presented principles are of course also applicable for inverters with bipolar transistors whatever the switched power.

	INFLUENCE OF PARASITIC EFFECTS ON THE SWITCHING AND COMMUTATION BEHAVlOR OF FAST POWER SEMICONDUCTOR DEVICES By G. Schulze; H. Stut; L. lorenz	[View] [Download]
Abstract: The aim of this paper is to show how the individual dissipative components of a transistor half-bridge configuration can be measured and the efficiency of the various types of transistor evaluated. The way in which a power transistor can be optimized for high clock frequencies in conjunction with a free-wheeling diode is also elaborated. In addition to the consideration of the power losses of a power semiconductor device, the controllability of short circuits is of ever increasing importance. Electrical behavior in the event of a short circuit is discussed, taking an IGBT half-bridge configuration as an example. Finally the parasitic effects which are particularly likely to occur during fast switching of an IGBT are explained.

	THE RING-EMITTER TRANSISTOR - A 20 KHZ HIGH-CURRENT SWITCH FOR PWM INVERTER APPLICATIONS By Samir F. Salama; Joachim Holtz	[View] [Download]
Abstract: The introduction of advanced microstructure technology in the fabrication of power semiconductor devices has created a new class of semiconductor switches with improved dynamic performance. The ring-emitter transistor SIRET is a product of the recent development in this area. This paper presents a study of the static characteristics and the dynamic switching performance of a half-bridge inverter built from a 50 A, 1000 V SIRET-Module. Owing to the special mechanical construction with minimized stray inductances, snubberless operation is possible at 20 kHz switching frequency. Special attention had to be given to thebase drive circuit as the switching performance of the device depends greatly on the base current waveform.

	MODELLING POWER MOSFET DC-DC CONVERTERS USING SPICE2 PROGRAM By E. Tatakis; J. Sanchez-Molero	[View] [Download]
Abstract: This paper deals with computer-aided analysis and simulation of a power mosfet dc-dc converter. Improved models for power mosfets and power diodes, adapted to SPICE2 are described in order to simulate accurately their static and dynamic behavior. The parameters of the models are determined using non-linear optimization methods. The variation of power mosfets on-resistance with drain current is considered and the variable gate-drain capacitance is simulated by an auxiliary network. Hence its possible to estimate with an excellent accuracy turn-on and turn-off wave forms, as well as switching and conduction losses. Models for power diodes are based upon the physical structure of a PIN diode. An auxiliary network is used to simulate the rate of decrease of the recovery current which plays an important role in power circuits containing inductances . We also demonstrate that noise voltages at the output terminals of the switching power supply can be predicted if we include the dominant parasitic elements in the models of passive components. To obtain accurate values of these spikes we have to take the layout into account by introducing the inductances of the connections. Simulated wave forms on a forward dc-dc converter and experimental results are in excellent agreement.

	DESIGN OF A 3-PHASE, MOSFET INVERTER AND ASSOCIATED GATE-DRIVE CIRCUIT By H. C. Lovatt; M. L. McClelland; M. J. Turner	[View] [Download]
Abstract: The paper discusses, with particular reference to the gate-drive circuit, the design of an inverter to reproduce a stored current waveform with a high degree of accuracy for use in a motor drive system. The gate-drive circuit combines low cost with individual overcurrent protection for each switch, thus providing shoot-through and short-circuit protection without the need or expense of a d.c. link choke. In addition to the gate-drive circuit design, the reasons for choosing MOSFETs as the main power devices, alternative gate-drive circuit configurations and inverter protection techniques are discussed. Although designed for a standard bridge configuration, MOSFET inverter, the gate-drive circuit presented is applicable to other MOS input devices and to other power circuit configurations.

	THE INSULATED GATE BIPOLAR TRANSISTOR: SWITCHING MODES By J. P. Ferrieux; F. Forest; P. Lienart	[View] [Download]
Abstract: The I.G.B.T. (insulated gate bipolar transistor), a very attractive device, seems to be the switch of the future, in medium power range. But since it is a new component, its behaviour is misjudged in particular switching modes. Once recalled principal characteristics of I.G.B.T., this paper deals with different switching modes (thyristor, dual-thyristor) to which are associated new types of high-frequency converters. These modes seems to release the best use of the device, as its appears in experimental results. Yet, this work points out latch-up and stored charge problems, in thyristor configuration and then, the necessity to define precisely the I.G.B.T. limitations in this mode, in order to allow conception of high-performing and low-cost converters.

	EXTENDED EBERS - MOLL'S MODEL OF SCR By W. Pietrenko	[View] [Download]
Abstract: The physical model of the SCR is proposed. The SCR as a one-dimensional pnpn structure is treated in the model. Some applications of the model are presented: the isothermal and nonisothermal D.C. characteristics of the modeled device, the computer simulation of the circuit with the SCR by SPICE and the short analysis of selected properties of the SCR.

	OVERCURRENT PROTECTION FOR POWER-MOSFETS By Th. Kalker	[View] [Download]
Abstract: The excellent switching capabilities of power MOSFETs permit the design of voltage fed inverters operating at high switching frequencies. By the use of FREDFETs the power circuit is very simple as no additional diodes and special snubbers are required. To ensure a safe operation of the inverter the switches have to be protected from overcurrent. In this paper a method is proposed to limit the drain current by modifying the gate driver characteristic. As a result a simple MOSFET driver is presented, which performs an overcurrent protection even under a short circuit condition. Its performance is proved by experimental measurements.