EPE Association: EPE 2005 - Topic 04-2 - LS: Multilevel converters

EPE 2005 - Topic 04-2 - LS: Multilevel converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 04: HARD SWITCHING CONVERTERS AND CONTROL > EPE 2005 - Topic 04-2 - LS: Multilevel converters

   [return to parent folder]

   A Five-Level Inverter Topology With Common mode Voltage Elimination for Induction Motor Drives
By R.S. Kanchan; K. Gopakumar; VEZZINI Andrea; TEKWANI P.N. [View]
[Download]

Abstract: Common-mode voltages generated by PWM inverters in induction motor drives cause shaft voltages, bearing currents and ground leakage currents resulting into early mechanical failure of machine bearings and conducted EMI. A five-level inverter topology with switching state combination selection strategy for the PWM control is proposed for an open-end winding induction motor drive, which completely eliminates the common-mode voltages at inverter poles and machine phase windings, in the complete modulation range of the drive. The proposed induction motor drive structure offers reduced device count, simple power-bus structure and more number of redundant switching state combinations when compared to a conventional five-level NPC inverter fed induction motor drive. The DC-link voltage requirement for the proposed five-level inverter fed drive scheme is half compared to that of conventional five-level inverter fed drive and hence it needs power devices with lower blocking voltage capability, which makes the proposed inverter topology suitable for high power induction motor drive applications.

   CONTROL TECHNIQUES FOR DC-LINK VOLTAGE RIPPLES MINIMIZATION IN CASCADED MULTILEVEL CONVERTER STRUCTURES
By LESKOVAR Stefania; MARCHESONI Mario [View]
[Download]

Abstract: Cascaded multilevel converters allow driving high power ac motors. Unfortunately, each H-bridge module is single-phase and the dc-link capacitance must be very large to reduce the dc-link voltage ripple. This paper shows how to minimize such a ripple by using new devised control techniques, while the most significant results are reported.

   Direct Torque Control for Stacked MultiCell (SMC) VSI fed induction machine
By BENNAN; GATEAU Guillaume; MEYNARD Thierry [View]
[Download]

Abstract: This paper deals with the control of SMC converters for an induction machine drive. Different degrees of freedom offered by this topology are addressed and used to develop strategies aiming to control electromagnetic variables of the machine, to balance three phase inverter switchings and inverter flying capacitor voltages. All of these techniques are designed to be used with an SMC converter with any number of levels.For the control of the electromagnetic state of the machine, a “direct control” based strategy is used. This technique is well-known for both torque and flux reduced ripple and high dynamics. These performances obviously increase with the number of levels of the inverter.Another degree of freedom of the SMC inverter is used to control the switching frequency. Two techniques are presented: The first aims to regulate the switching frequency and the second proposes to minimize the global number of switchings of the converter.Finally, the flying capacitor voltages are balanced using a third degree of freedom of the SMC converters. It is shown that the algorithm regulates the cell voltages, which implies a very good control of the capacitor voltages.Simulation results are shown for 7-, 9- and 11- level SMC inverter.

   Three-Dimensional Space Vector Modulation for a Four-Leg Three-Level Inverter
By YAO Jilong; GREEN Tim [View]
[Download]

Abstract: The trend toward deploying inverters in interfacing distributed generation (DG) systems to the grid has raised the importance of control and power quality aspects of inverters. Using multilevel inverters in DG systems, one can achieve highpower quality outputs with realistic switching frequency. The four-leg three-level inverter topology is proposed for DG applications in three-phase four-wire systems, for its full dc-link utilization and low voltage ripple on the dc-link capacitors. A novel algorithm for three-dimensional space vector modulation (3D-SVM) is proposed for controlling a four-leg three-level inverter. The issues of vector selection and switching sequence determination are described. Simulation results are compared with those of a three-leg three-level inverter to assessthe effectiveness of the proposed 3D-SVM and to establish the advantages of the four-leg three-level topology over conventional three-leg three-level one.

EPE 2005 - Topic 04-2 - LS: Multilevel converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2005 - Conference > EPE 2005 - Topic 04: HARD SWITCHING CONVERTERS AND CONTROL > EPE 2005 - Topic 04-2 - LS: Multilevel converters
	[return to parent folder]

	A Five-Level Inverter Topology With Common mode Voltage Elimination for Induction Motor Drives By R.S. Kanchan; K. Gopakumar; VEZZINI Andrea; TEKWANI P.N.	[View] [Download]
Abstract: Common-mode voltages generated by PWM inverters in induction motor drives cause shaft voltages, bearing currents and ground leakage currents resulting into early mechanical failure of machine bearings and conducted EMI. A five-level inverter topology with switching state combination selection strategy for the PWM control is proposed for an open-end winding induction motor drive, which completely eliminates the common-mode voltages at inverter poles and machine phase windings, in the complete modulation range of the drive. The proposed induction motor drive structure offers reduced device count, simple power-bus structure and more number of redundant switching state combinations when compared to a conventional five-level NPC inverter fed induction motor drive. The DC-link voltage requirement for the proposed five-level inverter fed drive scheme is half compared to that of conventional five-level inverter fed drive and hence it needs power devices with lower blocking voltage capability, which makes the proposed inverter topology suitable for high power induction motor drive applications.

	CONTROL TECHNIQUES FOR DC-LINK VOLTAGE RIPPLES MINIMIZATION IN CASCADED MULTILEVEL CONVERTER STRUCTURES By LESKOVAR Stefania; MARCHESONI Mario	[View] [Download]
Abstract: Cascaded multilevel converters allow driving high power ac motors. Unfortunately, each H-bridge module is single-phase and the dc-link capacitance must be very large to reduce the dc-link voltage ripple. This paper shows how to minimize such a ripple by using new devised control techniques, while the most significant results are reported.

	Direct Torque Control for Stacked MultiCell (SMC) VSI fed induction machine By BENNAN; GATEAU Guillaume; MEYNARD Thierry	[View] [Download]
Abstract: This paper deals with the control of SMC converters for an induction machine drive. Different degrees of freedom offered by this topology are addressed and used to develop strategies aiming to control electromagnetic variables of the machine, to balance three phase inverter switchings and inverter flying capacitor voltages. All of these techniques are designed to be used with an SMC converter with any number of levels.For the control of the electromagnetic state of the machine, a “direct control” based strategy is used. This technique is well-known for both torque and flux reduced ripple and high dynamics. These performances obviously increase with the number of levels of the inverter.Another degree of freedom of the SMC inverter is used to control the switching frequency. Two techniques are presented: The first aims to regulate the switching frequency and the second proposes to minimize the global number of switchings of the converter.Finally, the flying capacitor voltages are balanced using a third degree of freedom of the SMC converters. It is shown that the algorithm regulates the cell voltages, which implies a very good control of the capacitor voltages.Simulation results are shown for 7-, 9- and 11- level SMC inverter.

	Three-Dimensional Space Vector Modulation for a Four-Leg Three-Level Inverter By YAO Jilong; GREEN Tim	[View] [Download]
Abstract: The trend toward deploying inverters in interfacing distributed generation (DG) systems to the grid has raised the importance of control and power quality aspects of inverters. Using multilevel inverters in DG systems, one can achieve highpower quality outputs with realistic switching frequency. The four-leg three-level inverter topology is proposed for DG applications in three-phase four-wire systems, for its full dc-link utilization and low voltage ripple on the dc-link capacitors. A novel algorithm for three-dimensional space vector modulation (3D-SVM) is proposed for controlling a four-leg three-level inverter. The issues of vector selection and switching sequence determination are described. Simulation results are compared with those of a three-leg three-level inverter to assessthe effectiveness of the proposed 3D-SVM and to establish the advantages of the four-leg three-level topology over conventional three-leg three-level one.