EPE Association: EPE 1993 - 19 - Lecture Session L7a: DEVICES: GTO AND IGBT APPLICATIONS, THERMAL EFFECTS

EPE 1993 - 19 - Lecture Session L7a: DEVICES: GTO AND IGBT APPLICATIONS, THERMAL EFFECTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 19 - Lecture Session L7a: DEVICES: GTO AND IGBT APPLICATIONS, THERMAL EFFECTS

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   MAXIMUM SWITCHING FREQUENCY CHOICE FOR IGBT USED IN ZCS MODE
By S. Lefebvre; F. Forest; J.-P. Chante [View]
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Abstract: In the laboratory we have developed quasi-resonant converters using Z.C.S. (Zero Current Switching) mode. In these converters, operating at medium power and frequency range (a few kW and about 100 kHz), we used the IGBT (lnsulated Gate Bipolar Transistor) as a resonant thyristor. The experiment shows a frequency limit: higher frequencies lead to component failure by thermal instability for Punch-Through IGBT. We show that !he frequency limitation is due to a thermal phenomenon occurring in the bipolar transistor part of the IGBT: The charges injected into the component during the conduction phase have not all disappeared by recombination when the voltage is applied to the component. We have studied the variation of these charges and of the losses versus the temperature of the component in order to explain the thermal instability. The results allow us to predict the maximum working frequency of the IGBT in ZCS mode while avoiding failure of the studied component. The results are discussed and an IGBT, included in a forward resonant converter, has been experimentally studied to check the results. First, we show the different behaviours of Punch-through and Non-Punch-Through components with temperature, in ZCS. We show that the behaviour of NPT components is reliable in opposition to PT components. Thermal instability is impossible with NPT components. Such a study is shown to be the most efficient way of choosing the best adapted component to high frequency applications.

   GTO CHOPPER AT 2000 Hz SWITCHING FREQUENCY FOR A DC CURRENT SOURCE 1000 A - 1200 V
By G. Coquery; R. Lallemand; J. L. Peureux [View]
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Abstract: Thyristors GTO are used in choppers circuits to deliver a DC current to supply resonant power inverters or plasma are power devices. A 1,2 MW power is obtained with connection in parallel of two chopper modules including each one only one GTO switch with a DC rectifier. A 2000 Hz switching frequency is reached by using two choppers module with an overlapped 1000 Hz switch on. For each chopper the repetitive current commutated is 600 A onder the nominal DC voltage of 1200 V, this is possible without increasing GTO's switching losses by using the highly interdigited GTO's structure in the thyristors assisted operation mode. A protection is available against direct short-circuit on the output. A current regulation allows a good dynamic response on the whole current range. This paper discusses and describes the commutation principle of GTO, and shows oscillograms and experimental results at 1 MW output power on resistive load and plasma arc.

   ELECTRICAL TRANSIENTS OF SNUBBER DIODES IN GTO CIRCUITS
By P. T. Hoban; M. Rahimo; N. Y. A. Shammas [View]
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Abstract: During GTO operation the snubber diode is subjected to successive reversals of applied voltage bias. Such changes in bias produce voltage transients in the diode. Under conditions of large forward dl/dt the diode exhibits a transient forward volt drop. Under conditions of commutating dl/dt in an inductive circuit the diode recovery produces a reverse voltage overshoot. Optimising the forward recovery performance of the diode can have a detrimental effect on the reverse recovery performance. lt was found that all soft recovery diodes regardless of design can be made to exhibit snappy recovery. The diode has a soft recovery up to a critical dl/dt after which the device snaps-off producing dangerous voltage spikes. Such spikes can destroy the diode and cause a subsequent circuit failure. This change in recovery characteristic at high dl/dt and circuit inductance must be allowed for in the design of the GTO circuit.

   SWITCHING CHARACTERISTIC IMPROVEMENT OF MODERN GATE CONTROLLED DEVICES
By A. Galluzzo; M. Melito; G. Belverde; S. Musumeci; A. Raciti; A. Testa [View]
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Abstract: The raising use of insulated gate devices, such as Power MOSFETs and IGBTs, in power electronic circuits is due to both the easy driving and the ability to handle high currents and voltages at high frequency. By increasing the switching speed it is possible to reduce the power dissipation although at the cost of an increased generation of electro-magnetic interferences (EMI). The aim of this paper is to illustrate a new driver circuit topology that allows to obtain an acceptable compromise between switching speed, power dissipation and electro magnetic irradiation. The paper starts with an analysis of voltage and current switching waveforms then points on those characteristics of the devices and driving circuils that influence the switching speed and finally shows how to control voltage and current slopes independently by using a suitable driving technique.

EPE 1993 - 19 - Lecture Session L7a: DEVICES: GTO AND IGBT APPLICATIONS, THERMAL EFFECTS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 19 - Lecture Session L7a: DEVICES: GTO AND IGBT APPLICATIONS, THERMAL EFFECTS
	[return to parent folder]

	MAXIMUM SWITCHING FREQUENCY CHOICE FOR IGBT USED IN ZCS MODE By S. Lefebvre; F. Forest; J.-P. Chante	[View] [Download]
Abstract: In the laboratory we have developed quasi-resonant converters using Z.C.S. (Zero Current Switching) mode. In these converters, operating at medium power and frequency range (a few kW and about 100 kHz), we used the IGBT (lnsulated Gate Bipolar Transistor) as a resonant thyristor. The experiment shows a frequency limit: higher frequencies lead to component failure by thermal instability for Punch-Through IGBT. We show that !he frequency limitation is due to a thermal phenomenon occurring in the bipolar transistor part of the IGBT: The charges injected into the component during the conduction phase have not all disappeared by recombination when the voltage is applied to the component. We have studied the variation of these charges and of the losses versus the temperature of the component in order to explain the thermal instability. The results allow us to predict the maximum working frequency of the IGBT in ZCS mode while avoiding failure of the studied component. The results are discussed and an IGBT, included in a forward resonant converter, has been experimentally studied to check the results. First, we show the different behaviours of Punch-through and Non-Punch-Through components with temperature, in ZCS. We show that the behaviour of NPT components is reliable in opposition to PT components. Thermal instability is impossible with NPT components. Such a study is shown to be the most efficient way of choosing the best adapted component to high frequency applications.

	GTO CHOPPER AT 2000 Hz SWITCHING FREQUENCY FOR A DC CURRENT SOURCE 1000 A - 1200 V By G. Coquery; R. Lallemand; J. L. Peureux	[View] [Download]
Abstract: Thyristors GTO are used in choppers circuits to deliver a DC current to supply resonant power inverters or plasma are power devices. A 1,2 MW power is obtained with connection in parallel of two chopper modules including each one only one GTO switch with a DC rectifier. A 2000 Hz switching frequency is reached by using two choppers module with an overlapped 1000 Hz switch on. For each chopper the repetitive current commutated is 600 A onder the nominal DC voltage of 1200 V, this is possible without increasing GTO's switching losses by using the highly interdigited GTO's structure in the thyristors assisted operation mode. A protection is available against direct short-circuit on the output. A current regulation allows a good dynamic response on the whole current range. This paper discusses and describes the commutation principle of GTO, and shows oscillograms and experimental results at 1 MW output power on resistive load and plasma arc.

	ELECTRICAL TRANSIENTS OF SNUBBER DIODES IN GTO CIRCUITS By P. T. Hoban; M. Rahimo; N. Y. A. Shammas	[View] [Download]
Abstract: During GTO operation the snubber diode is subjected to successive reversals of applied voltage bias. Such changes in bias produce voltage transients in the diode. Under conditions of large forward dl/dt the diode exhibits a transient forward volt drop. Under conditions of commutating dl/dt in an inductive circuit the diode recovery produces a reverse voltage overshoot. Optimising the forward recovery performance of the diode can have a detrimental effect on the reverse recovery performance. lt was found that all soft recovery diodes regardless of design can be made to exhibit snappy recovery. The diode has a soft recovery up to a critical dl/dt after which the device snaps-off producing dangerous voltage spikes. Such spikes can destroy the diode and cause a subsequent circuit failure. This change in recovery characteristic at high dl/dt and circuit inductance must be allowed for in the design of the GTO circuit.

	SWITCHING CHARACTERISTIC IMPROVEMENT OF MODERN GATE CONTROLLED DEVICES By A. Galluzzo; M. Melito; G. Belverde; S. Musumeci; A. Raciti; A. Testa	[View] [Download]
Abstract: The raising use of insulated gate devices, such as Power MOSFETs and IGBTs, in power electronic circuits is due to both the easy driving and the ability to handle high currents and voltages at high frequency. By increasing the switching speed it is possible to reduce the power dissipation although at the cost of an increased generation of electro-magnetic interferences (EMI). The aim of this paper is to illustrate a new driver circuit topology that allows to obtain an acceptable compromise between switching speed, power dissipation and electro magnetic irradiation. The paper starts with an analysis of voltage and current switching waveforms then points on those characteristics of the devices and driving circuils that influence the switching speed and finally shows how to control voltage and current slopes independently by using a suitable driving technique.