EPE Association: EPE 1993 - 03 - Lecture Session L1c: DRIVES: CONFIGURATIONS, 3 LEVEL, 6 PULSE

EPE 1993 - 03 - Lecture Session L1c: DRIVES: CONFIGURATIONS, 3 LEVEL, 6 PULSE
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 03 - Lecture Session L1c: DRIVES: CONFIGURATIONS, 3 LEVEL, 6 PULSE

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   ARE PARALLELED IGBT MODULES OR PARALLELED IGBT INVERTERS THE BETTER CHOICE?
By Ch. Keller; Y. Tadros [View]
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Abstract: The power range which can be handled by PWM inverter applying available IGBT modules is about 150kW. For higher power levels more than one device per bridge arm is necessary. In this paper possibilities to enlarge output power of IGBT inverters using parallel circuit are discussed . For direct parallel operation of advanced IGBT devices difficulties are caused by negative temperature coefficient of on-state voltage. This includes a risk of thermal runaway or large imbalance of current sharing. The necessary conditions for a good current balance will be deduced. Satisfying these conditions, direct paralleling of high current IGBT modules is possible up to three devices. For higher power levels with a larger number of IGBT modules it is not possible to achieve close thermal coupling which is essential for good on-state current sharing. For such higher power-levels paralleled inverters with electronic controlled current imbalance are advisable.

   CONFIGURATIONS OF HIGH-POWER VOLTAGE SOURCE INVERTER DRIVES
By H. Stemmler; P. Guggenbach [View]
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Abstract: Synchronous machines fed by current source or cyclo-converters have become standard solutions in high power applications. Mains side current shape and fundamental power factor are problems that arise using this type of drives. Therefore, recent developments tend to use induction machines fed by voltage source inverters ( VSIs ) also for high power drives. Inherent advantages are: A simple and less expensive induction motor which leads to an overall economic solution with a good power factor over the whole operation range. However, the switching and snubber-losses of the gate turn-off thyristors ( GTOs ) limit the switching frequency to only a few hundred Hertz. This leads to severe drawbacks: high harmonics, low efficiency and low maximum speed. In order to eliminate these drawbacks, the paper will present and compare improved solutions: Combinations with series connected 2-level and 3-level VSls and motors with 3 and 6 connections to the windings.

   COMPARISON OF TRUE RUNNING AT DIFFERENT CONCEPTS OF CONTROLLING BRUSHLESS DC-MOTORS
By J. Kempkes; Ph. K. Sattler [View]
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Abstract: A comparison of true running between serve-drives has been performed until now only by examination of the torque ripple. As the torque ripple can only be minimized - several possibilities are shown briefly in the presented paper - the influence of the current control method and of the speed controlling concept can not be neglected because of the controllers capabilities to reduce the always existing torque ripple of a brushless dc-motor. In order to investigate these capabilities a new method of measurement and suitable criterias are to be introduced. The measurement system presented in this paper allows to examine the variation of speed and acceleration very precisely after an off-line evaluation of the measurement data-set, whereas the presented criterias are used for the real comparison of the servo-drives concerning their true running. The control concepts compared in this paper are: PI-speed-controller combined with rectangular and sinusoidal current waveforms, current waveforms with additional harmonics in order to compensate known (i.e. measured) torque ripple and a state controller with a load torque observer.

EPE 1993 - 03 - Lecture Session L1c: DRIVES: CONFIGURATIONS, 3 LEVEL, 6 PULSE
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 03 - Lecture Session L1c: DRIVES: CONFIGURATIONS, 3 LEVEL, 6 PULSE
	[return to parent folder]

	ARE PARALLELED IGBT MODULES OR PARALLELED IGBT INVERTERS THE BETTER CHOICE? By Ch. Keller; Y. Tadros	[View] [Download]
Abstract: The power range which can be handled by PWM inverter applying available IGBT modules is about 150kW. For higher power levels more than one device per bridge arm is necessary. In this paper possibilities to enlarge output power of IGBT inverters using parallel circuit are discussed . For direct parallel operation of advanced IGBT devices difficulties are caused by negative temperature coefficient of on-state voltage. This includes a risk of thermal runaway or large imbalance of current sharing. The necessary conditions for a good current balance will be deduced. Satisfying these conditions, direct paralleling of high current IGBT modules is possible up to three devices. For higher power levels with a larger number of IGBT modules it is not possible to achieve close thermal coupling which is essential for good on-state current sharing. For such higher power-levels paralleled inverters with electronic controlled current imbalance are advisable.

	CONFIGURATIONS OF HIGH-POWER VOLTAGE SOURCE INVERTER DRIVES By H. Stemmler; P. Guggenbach	[View] [Download]
Abstract: Synchronous machines fed by current source or cyclo-converters have become standard solutions in high power applications. Mains side current shape and fundamental power factor are problems that arise using this type of drives. Therefore, recent developments tend to use induction machines fed by voltage source inverters ( VSIs ) also for high power drives. Inherent advantages are: A simple and less expensive induction motor which leads to an overall economic solution with a good power factor over the whole operation range. However, the switching and snubber-losses of the gate turn-off thyristors ( GTOs ) limit the switching frequency to only a few hundred Hertz. This leads to severe drawbacks: high harmonics, low efficiency and low maximum speed. In order to eliminate these drawbacks, the paper will present and compare improved solutions: Combinations with series connected 2-level and 3-level VSls and motors with 3 and 6 connections to the windings.

	COMPARISON OF TRUE RUNNING AT DIFFERENT CONCEPTS OF CONTROLLING BRUSHLESS DC-MOTORS By J. Kempkes; Ph. K. Sattler	[View] [Download]
Abstract: A comparison of true running between serve-drives has been performed until now only by examination of the torque ripple. As the torque ripple can only be minimized - several possibilities are shown briefly in the presented paper - the influence of the current control method and of the speed controlling concept can not be neglected because of the controllers capabilities to reduce the always existing torque ripple of a brushless dc-motor. In order to investigate these capabilities a new method of measurement and suitable criterias are to be introduced. The measurement system presented in this paper allows to examine the variation of speed and acceleration very precisely after an off-line evaluation of the measurement data-set, whereas the presented criterias are used for the real comparison of the servo-drives concerning their true running. The control concepts compared in this paper are: PI-speed-controller combined with rectangular and sinusoidal current waveforms, current waveforms with additional harmonics in order to compensate known (i.e. measured) torque ripple and a state controller with a load torque observer.