EPE Association: EPE 2005 - Topic 04-3b - DS: Multilevel and matrix converters, Emerging topologies

EPE 2005 - Topic 04-3b - DS: Multilevel and matrix converters, Emerging topologies
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 04-3b - DS: Multilevel and matrix converters, Emerging topologies

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   A new space vector modulation scheme for three phase four wire inverter for standalone photovoltaic systems
By SALEM Fouzey; UeNSALVER Caner; HOFMANN W.; E [View]
[Download]

Abstract: Three phase inverters with unbalanced load have a lot of disadvantages like small utilisation of the DC-link voltage, dependency of the modulation factor of the load current, and the superposition of a DC component with the output AC voltage. The four-phase inverter is able to supply both symmetrical and asymmetrical consumers in the three-phase standalone photovoltaic nets. By the additional half bridge possible to reduce the DC-link voltage by 16\% and dc-link capacity by 35\%. In this paper a three dimensional space vector modulation for a four leg inverter for standalone photovoltaic systems is presented to solve these problems. A digital control based on a load current observer will be implemented according to [1], to control the whole system with a microcontroller. Simulation results are presented to verify the performance of the proposed system.

   An Indirect Matrix Converter with a Cost Effective Protection and Control
By KLUMPNER Christian [View]
[Download]

Abstract: The cost of protection circuits and transducers for protection and control purposes play an important part when evaluating the potential of a converter topology for mass production. Direct power converters are known to require minimum size of the passive components in the input filter, but they require a large number of semiconductor devices and the use of protection/clamp circuits that further increase the circuit complexity and cost. This paper will survey a few known techniques to simplify and reduce the number of devices involved in protection circuits and control of Indirect Matrix Converters (IMC) and will propose a few new ones.

   Analysis of Partially Controllable Multi-level Voltage Source Converters
By OBRIEN Kathleen; TEICHMANN Ralph; GUELDNER Henry [View]
[Download]

Abstract: In partially controllable multi-level converters the displacement power factor range and the voltage transfer ratio boundaries depend on the number of converter levels. Partially controllable multi-level converters are characterized by asymmetric power flow capabilities. Part count, blocking voltage requirements, and the boundaries and stability of circuit operation are evaluated for various circuit configurations.

   Efficiency Comparison of Voltage Source and Current Source Drive Systemfor Medium Voltage Applications
By STEINKE Juergen; SUH Yongsug; STEIMER Peter [View]
[Download]

Abstract: This paper calculates and compares the efficiency and loss distribution in three most popular state-of-the-art types of medium voltage drive systems; current source drive with active front-end rectifier, current source drive with 18-pulse thyristor rectifier, and three-level voltage source drive with 12-pulse/24-pulse diode rectifier. Based on the proposed simple and accurate method of calculating switching losses, snubber and filter losses, three-level voltage source drive system has been found to produce the highest efficiency of 98.44\% under the rated load of 1.6 MW.

   Efficient Predictive Current Control Technique for Multilevel Voltage Source Inverters
By XEPAPAS Fotis; PERANTZAKIS George; MANIAS Stefanos [View]
[Download]

Abstract: In this paper a predictive current control technique for Multilevel Voltage Source Inverters (MVSI) is presented. The proposed method can be applied to any multilevel inverter for high-voltage high-power applications. Here, it is applied to a four-level Neutral-Point Diode Clamped Voltage Source Inverter (NPDCVSI). The inverter is considered as a non-linear system with its thirty seven discrete space voltage vectors.The proposed controller predicts the load current for all voltage vectors generated by the inverter. The current error for each voltage vector is calculated and the vector that ensures the smallest value of current error is selected as the inverter voltage vector for the next sampling time.The method allows optimum reference current tracking for all operating conditions under low current harmonic distortion as a result of many voltage vectors that participate in the control process. Furthermore, the proposed control ensures fast dynamic response and decoupling effect between the load current components. Simulation and experimental results verify the effectiveness of the predictive current controller.

   Experimental validation of multilevel converters for variable speed wind turbines
By ROBLES Eider; VILLATE Jose Luis; GABIOLA Igor; CEBALLOS Salvador; IBAÑEZ Pedro [View]
[Download]

Abstract: Wind energy is undergoing a rapid development in size and capacity. Multilevel converters show interesting advantages in this field, such as high efficiency and low harmonic distortion. This work is focused on the analysis of these two features offering experimental results which verify the improvement of this kind of converters on the traditional two level topologies. Finally, we describe an experimental test bench where we intend to continue the validation of other features of multilevel converters such as performance under voltage sags and wind speed variations.

   Improvement of output voltage capability of a two stage direct power converter under unbalanced input voltages
By KLUMPNER Christian ; WIJEKOON Thiwanka; WHEELER Patrick [View]
[Download]

Abstract: Direct Power Converters (DPC), which has no energy storage, the converter output voltage capability is affected when the input voltage is unbalanced. This paper proposes the utilization of the clamp capacitor, which is normally needed to protect a DPC, to extend the operating range of a two stage DPC during unbalanced supply, preserving its theoretical output voltage capability. A comprehensive simulation study with analytical explanations justifies the proposed method. Experimental results using a laboratory prototype confirms the viability of the proposed active compensation technique.

   INFLUENCE OF ROV UMBILICAL ON POWER QUALITY WHEN SUPPLYING ELECTRICAL THRUSTER LOADS
By BINGHAM Chris; STONE Dave; PAUL SNARY Paul [View]
[Download]

Abstract: The paper investigates the effects of a 3km electrical umbilical cable on power transmission for an “island” supply onboard an all/more electric ‘work-class’ Remote Operated Vehicle (ROV). It is shown how the chosen transmission voltage and frequency influence efficiency and the selection of power transmission components. A key feature of the paper is a discussion on the use of matrix converters for the propulsion thruster drive system; thereby allowing the input displacement factor to be varied to maintain maximum power transmission efficiency, independent of the thruster power factor. The natural impedance characteristics of the umbilical cable are also considered as means of reducing the input filter requirements for such converters.

   Low Input Current Ripple Converters for Fuel Cell Power Units
By TRIOLO Domenico; DE CARO Salvatore; TESTA Antonio; CONSOLI Alfio; CACCIATO Mario [View]
[Download]

Abstract: Proton Exchange Membrane Fuel Cell (PEMFC) generators are today considered as a viable solution to the development of auxiliary, or back up, power units for automotive, computer and telecommunications systems. Several of these applications require a power conditioner with high efficiency, high conversion ratio and very low input current ripple to interface the fuel cell generator to a high-voltage DC bus. In this paper, two step-up non insulated DC/DC converter topologies, suitable to equip low power fuel cell power units are developed and deeply examined. A key feature of the two proposed converters is that they are obtained by mixing some basic topologies, in order to optimize both duty cycle and the winding ratio. Moreover, multichannel interleaved power conversion structures are adopted in order to reduce the size of input and output filters. Finally, both the proposed topologies feature an input inductance, that plays a major role in lowering the fuel cell output current ripple, thus reducing fuel consumption. The two proposed converters are theoretically analyzed and experimentally tested.

   New Control strategy for a Naturally Commutated Matrix Converter for Variable Speed Constant Frequency (VSCF) Generating System
By DEPERNET Daniel; KAUFFMANN Jean Marie; MILIANI El Hadj [View]
[Download]

Abstract: Several industrial applications require the production of an accurately regulated frequency power output, from a variable frequency power source; such as variable speed constant frequency generating systems (VSCF) for aircraft and mobile power supplies. A new control strategy based on the cosine wave crossing control is applied to a naturally commutated matrix converter in a VSCF generating system. A VSCF generating system is obtained by using a new and innovative topology composed by a six phases permanent magnet synchronous generator (PMSG) and a six to three phase naturally commutated matrix converter (NCMC). This kind of generator is used with the aim of avoiding mechanical gear-box and improves gas turbine efficiency. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. With the progress of high speed, lower cost digital signal processing (DSP), there has been a blossoming use of DSP techniques especially in power converters control. The proposed control strategy was successfully simulated and implemented on a fixed point TMS320LF2407 Texas Instruments device. Comparison of simulation results with experimental test results are given in this paper.

   Power balancing of a multilevel converter with two insulated supplies
By GRANDI Gabriele; CASADEI Domenico; LEGA Alberto; ROSSI Claudio [View]
[Download]

Abstract: A multilevel converter topology feeding three-phase open-end winding loads is considered in this paper. The scheme is based on two insulated dc supplies, each one feeding a standard two-level, three-phase inverter. A three-phase, six wires load is connected across the output terminals. A new modulation technique able to regulate the sharing of the output power between the two dc sources within each switching cycle is presented. The performance of the whole system has been verified by numerical simulations.

   Simplified linear-quadratic regulator applied to a three-level converter
By RODRIGUEZ Pedro; CANDELA InAki; BOROYEVICH Dushan; PINDADO Rafael; POU Josep [View]
[Download]

Abstract: A linear-quadratic regulator is applied to a three-level converter that can operate under rectifier mode with power factor control. The regulator is simplified because it is relieved from the task of balancing voltages on the DC-link capacitors, which is carried out in the modulation stage. The algorithm takes into account the one-period delay intrinsic to the pulsewidth modulation (PWM), and it also includes an integral actuator to remove the steady state errors. Experimental results are presented.

   Stacked Multicell Converter (SMC): Estimation of flying capacitors voltages
By GATEAU Guillaume; MEYNARD Thierry; LIENHARDT Ann [View]
[Download]

Abstract: This paper introduces a new estimation technique of the flying capacitor voltages dedicated to Stacked Multicell Converters (SMC). Those voltages have to remain constant during the operation of the converter so as to ensure the proper repartition of the voltage constraints over the commutation cells. This objective can be achieved by implementing an active control of the capacitor voltages, which requires the knowledge of those quantities at each time. However it is both difficult and expensive to measure them because of the high voltage/power range of applications. Thus we move toward the development of an estimation of those quantities. After an introduction and a succinct reminder on the SMC topology, the first part describes the new strategy for the estimation of the capacitor voltages. It is based on a real-time simulation of the state-space model of the system. To prevent this emulator from drifting away, an update should be included in the estimation procedure by the use of an extra voltage measurement. The second main part is devoted to the influence of the current or the voltage sensing noise on our approach and the development of appropriate strategies to counter those phenomena.

   Straight Forward Control of the Matrix Converter
By CLOS Gerhard [View]
[Download]

Abstract: This paper proposes a new modulation strategy for the matrix converter. Only the instantaneous values of the input voltages, of the output currents and the wanted output voltages and wanted reactive input currents are needed to create the switching functions - including neutral function and common-mode terms - for obtaining the maximum control range.

EPE 2005 - Topic 04-3b - DS: Multilevel and matrix converters, Emerging topologies
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 04-3b - DS: Multilevel and matrix converters, Emerging topologies
	[return to parent folder]

	A new space vector modulation scheme for three phase four wire inverter for standalone photovoltaic systems By SALEM Fouzey; UeNSALVER Caner; HOFMANN W.; E	[View] [Download]
Abstract: Three phase inverters with unbalanced load have a lot of disadvantages like small utilisation of the DC-link voltage, dependency of the modulation factor of the load current, and the superposition of a DC component with the output AC voltage. The four-phase inverter is able to supply both symmetrical and asymmetrical consumers in the three-phase standalone photovoltaic nets. By the additional half bridge possible to reduce the DC-link voltage by 16\% and dc-link capacity by 35\%. In this paper a three dimensional space vector modulation for a four leg inverter for standalone photovoltaic systems is presented to solve these problems. A digital control based on a load current observer will be implemented according to [1], to control the whole system with a microcontroller. Simulation results are presented to verify the performance of the proposed system.

	An Indirect Matrix Converter with a Cost Effective Protection and Control By KLUMPNER Christian	[View] [Download]
Abstract: The cost of protection circuits and transducers for protection and control purposes play an important part when evaluating the potential of a converter topology for mass production. Direct power converters are known to require minimum size of the passive components in the input filter, but they require a large number of semiconductor devices and the use of protection/clamp circuits that further increase the circuit complexity and cost. This paper will survey a few known techniques to simplify and reduce the number of devices involved in protection circuits and control of Indirect Matrix Converters (IMC) and will propose a few new ones.

	Analysis of Partially Controllable Multi-level Voltage Source Converters By OBRIEN Kathleen; TEICHMANN Ralph; GUELDNER Henry	[View] [Download]
Abstract: In partially controllable multi-level converters the displacement power factor range and the voltage transfer ratio boundaries depend on the number of converter levels. Partially controllable multi-level converters are characterized by asymmetric power flow capabilities. Part count, blocking voltage requirements, and the boundaries and stability of circuit operation are evaluated for various circuit configurations.

	Efficiency Comparison of Voltage Source and Current Source Drive Systemfor Medium Voltage Applications By STEINKE Juergen; SUH Yongsug; STEIMER Peter	[View] [Download]
Abstract: This paper calculates and compares the efficiency and loss distribution in three most popular state-of-the-art types of medium voltage drive systems; current source drive with active front-end rectifier, current source drive with 18-pulse thyristor rectifier, and three-level voltage source drive with 12-pulse/24-pulse diode rectifier. Based on the proposed simple and accurate method of calculating switching losses, snubber and filter losses, three-level voltage source drive system has been found to produce the highest efficiency of 98.44\% under the rated load of 1.6 MW.

	Efficient Predictive Current Control Technique for Multilevel Voltage Source Inverters By XEPAPAS Fotis; PERANTZAKIS George; MANIAS Stefanos	[View] [Download]
Abstract: In this paper a predictive current control technique for Multilevel Voltage Source Inverters (MVSI) is presented. The proposed method can be applied to any multilevel inverter for high-voltage high-power applications. Here, it is applied to a four-level Neutral-Point Diode Clamped Voltage Source Inverter (NPDCVSI). The inverter is considered as a non-linear system with its thirty seven discrete space voltage vectors.The proposed controller predicts the load current for all voltage vectors generated by the inverter. The current error for each voltage vector is calculated and the vector that ensures the smallest value of current error is selected as the inverter voltage vector for the next sampling time.The method allows optimum reference current tracking for all operating conditions under low current harmonic distortion as a result of many voltage vectors that participate in the control process. Furthermore, the proposed control ensures fast dynamic response and decoupling effect between the load current components. Simulation and experimental results verify the effectiveness of the predictive current controller.

	Experimental validation of multilevel converters for variable speed wind turbines By ROBLES Eider; VILLATE Jose Luis; GABIOLA Igor; CEBALLOS Salvador; IBAÑEZ Pedro	[View] [Download]
Abstract: Wind energy is undergoing a rapid development in size and capacity. Multilevel converters show interesting advantages in this field, such as high efficiency and low harmonic distortion. This work is focused on the analysis of these two features offering experimental results which verify the improvement of this kind of converters on the traditional two level topologies. Finally, we describe an experimental test bench where we intend to continue the validation of other features of multilevel converters such as performance under voltage sags and wind speed variations.

	Improvement of output voltage capability of a two stage direct power converter under unbalanced input voltages By KLUMPNER Christian ; WIJEKOON Thiwanka; WHEELER Patrick	[View] [Download]
Abstract: Direct Power Converters (DPC), which has no energy storage, the converter output voltage capability is affected when the input voltage is unbalanced. This paper proposes the utilization of the clamp capacitor, which is normally needed to protect a DPC, to extend the operating range of a two stage DPC during unbalanced supply, preserving its theoretical output voltage capability. A comprehensive simulation study with analytical explanations justifies the proposed method. Experimental results using a laboratory prototype confirms the viability of the proposed active compensation technique.

	INFLUENCE OF ROV UMBILICAL ON POWER QUALITY WHEN SUPPLYING ELECTRICAL THRUSTER LOADS By BINGHAM Chris; STONE Dave; PAUL SNARY Paul	[View] [Download]
Abstract: The paper investigates the effects of a 3km electrical umbilical cable on power transmission for an “island” supply onboard an all/more electric ‘work-class’ Remote Operated Vehicle (ROV). It is shown how the chosen transmission voltage and frequency influence efficiency and the selection of power transmission components. A key feature of the paper is a discussion on the use of matrix converters for the propulsion thruster drive system; thereby allowing the input displacement factor to be varied to maintain maximum power transmission efficiency, independent of the thruster power factor. The natural impedance characteristics of the umbilical cable are also considered as means of reducing the input filter requirements for such converters.

	Low Input Current Ripple Converters for Fuel Cell Power Units By TRIOLO Domenico; DE CARO Salvatore; TESTA Antonio; CONSOLI Alfio; CACCIATO Mario	[View] [Download]
Abstract: Proton Exchange Membrane Fuel Cell (PEMFC) generators are today considered as a viable solution to the development of auxiliary, or back up, power units for automotive, computer and telecommunications systems. Several of these applications require a power conditioner with high efficiency, high conversion ratio and very low input current ripple to interface the fuel cell generator to a high-voltage DC bus. In this paper, two step-up non insulated DC/DC converter topologies, suitable to equip low power fuel cell power units are developed and deeply examined. A key feature of the two proposed converters is that they are obtained by mixing some basic topologies, in order to optimize both duty cycle and the winding ratio. Moreover, multichannel interleaved power conversion structures are adopted in order to reduce the size of input and output filters. Finally, both the proposed topologies feature an input inductance, that plays a major role in lowering the fuel cell output current ripple, thus reducing fuel consumption. The two proposed converters are theoretically analyzed and experimentally tested.

	New Control strategy for a Naturally Commutated Matrix Converter for Variable Speed Constant Frequency (VSCF) Generating System By DEPERNET Daniel; KAUFFMANN Jean Marie; MILIANI El Hadj	[View] [Download]
Abstract: Several industrial applications require the production of an accurately regulated frequency power output, from a variable frequency power source; such as variable speed constant frequency generating systems (VSCF) for aircraft and mobile power supplies. A new control strategy based on the cosine wave crossing control is applied to a naturally commutated matrix converter in a VSCF generating system. A VSCF generating system is obtained by using a new and innovative topology composed by a six phases permanent magnet synchronous generator (PMSG) and a six to three phase naturally commutated matrix converter (NCMC). This kind of generator is used with the aim of avoiding mechanical gear-box and improves gas turbine efficiency. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. With the progress of high speed, lower cost digital signal processing (DSP), there has been a blossoming use of DSP techniques especially in power converters control. The proposed control strategy was successfully simulated and implemented on a fixed point TMS320LF2407 Texas Instruments device. Comparison of simulation results with experimental test results are given in this paper.

	Power balancing of a multilevel converter with two insulated supplies By GRANDI Gabriele; CASADEI Domenico; LEGA Alberto; ROSSI Claudio	[View] [Download]
Abstract: A multilevel converter topology feeding three-phase open-end winding loads is considered in this paper. The scheme is based on two insulated dc supplies, each one feeding a standard two-level, three-phase inverter. A three-phase, six wires load is connected across the output terminals. A new modulation technique able to regulate the sharing of the output power between the two dc sources within each switching cycle is presented. The performance of the whole system has been verified by numerical simulations.

	Simplified linear-quadratic regulator applied to a three-level converter By RODRIGUEZ Pedro; CANDELA InAki; BOROYEVICH Dushan; PINDADO Rafael; POU Josep	[View] [Download]
Abstract: A linear-quadratic regulator is applied to a three-level converter that can operate under rectifier mode with power factor control. The regulator is simplified because it is relieved from the task of balancing voltages on the DC-link capacitors, which is carried out in the modulation stage. The algorithm takes into account the one-period delay intrinsic to the pulsewidth modulation (PWM), and it also includes an integral actuator to remove the steady state errors. Experimental results are presented.

	Stacked Multicell Converter (SMC): Estimation of flying capacitors voltages By GATEAU Guillaume; MEYNARD Thierry; LIENHARDT Ann	[View] [Download]
Abstract: This paper introduces a new estimation technique of the flying capacitor voltages dedicated to Stacked Multicell Converters (SMC). Those voltages have to remain constant during the operation of the converter so as to ensure the proper repartition of the voltage constraints over the commutation cells. This objective can be achieved by implementing an active control of the capacitor voltages, which requires the knowledge of those quantities at each time. However it is both difficult and expensive to measure them because of the high voltage/power range of applications. Thus we move toward the development of an estimation of those quantities. After an introduction and a succinct reminder on the SMC topology, the first part describes the new strategy for the estimation of the capacitor voltages. It is based on a real-time simulation of the state-space model of the system. To prevent this emulator from drifting away, an update should be included in the estimation procedure by the use of an extra voltage measurement. The second main part is devoted to the influence of the current or the voltage sensing noise on our approach and the development of appropriate strategies to counter those phenomena.

	Straight Forward Control of the Matrix Converter By CLOS Gerhard	[View] [Download]
Abstract: This paper proposes a new modulation strategy for the matrix converter. Only the instantaneous values of the input voltages, of the output currents and the wanted output voltages and wanted reactive input currents are needed to create the switching functions - including neutral function and common-mode terms - for obtaining the maximum control range.