Three phase transformation for simplified space vector control of multilevel inverters

Schäfer, Markus; Goetze, Wolf; Hofmann, Martin Ludwig; Montesinos‐Miracle, Daniel; Ackva, Ansgar

doi:10.1109/compel.2015.7236453

Cited by 8 publications

(6 citation statements)

References 18 publications

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“…The control algorithm is based on a special three phase transformation ideally suited for FPGA implementation to locate the sector of the reference voltage vector in the space vector plane [20]. The three phase voltages are described in a non-orthogonal a * b * -coordinate system which enables fast fixed point calculations as only integer values are used to describe the states.…”

Section: B Transformationmentioning

confidence: 99%

“…The three phase voltages are described in a non-orthogonal a * b * -coordinate system which enables fast fixed point calculations as only integer values are used to describe the states. The transformation, as derived in [20], is given by…”

Section: B Transformationmentioning

confidence: 99%

“…Using this transformation matrix, the determination of the sector for control and the redundant states is achieved by the following three steps derived in [20]:…”

Section: B Transformationmentioning

confidence: 99%

“…This paper introduces a new FPGA based direct current control algorithm for grid connected inverters. Based on a three phase transformation [20], which is ideally suited for fixed point arithmetic, the algorithm controls the current quasicontinuously. A generic approach enables easy adaption to higher-level systems.…”

Section: Introductionmentioning

confidence: 99%

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Direct Current Control for Grid-Connected Diode-Clamped Inverters

Schaefer

Goetze

Hofmann

et al. 2017

IEEE Trans. Ind. Electron.

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Abstract-The accurate control of the line current, robust and dynamic behavior even under distorted grids and other system faults are the most important requirements for grid connected inverters. Applying direct current control to multilevel inverters combines the advantages of both and is an enabling step towards improved inverter performance. Direct current controllers suffer from high complexity at increased level count, which is resolved using geometrical principles and simple analytical calculations for switching vector selection within the space vector diagram. The simplified, novel parametric controller concept is scalable to inverters with arbitrary level count, does not require any switching tables and the new fully symmetric setup guarantees equal switching frequencies among the three phases. The hypotheses are further confirmed on a real hardware test setup on the example of a 3-level NPC inverter hardware and a Xilinx development platform. Experimental results prove the expected behavior of the direct current control under various conditions, shows a general approach to balance the DC-link capacitors of diode-clamped inverters within the theoretical limits and demonstrates the benefits of using Field Programmable Gate Arrays (FPGA) as a controller platform.

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Section: B Transformationmentioning

confidence: 99%

Section: B Transformationmentioning

confidence: 99%

“…Using this transformation matrix, the determination of the sector for control and the redundant states is achieved by the following three steps derived in [20]:…”

Section: B Transformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct Current Control for Grid-Connected Diode-Clamped Inverters

Schaefer

Goetze

Hofmann

et al. 2017

IEEE Trans. Ind. Electron.

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“…Therefore, the midpoint of the active triangle is selected as an auxiliary ("pseudo") voltage. For simplification and midpoint definition a new coordinate transformation is applied in the SV-diagram [64]. The basic functionality of this coordinate transformation will be described in more detail in Chapter 4.4.1.…”

Section: Inner Tolerance Bandmentioning

confidence: 99%

Improved control for multilevel inverters in grid applications

Hofmann¹

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Control systems for three-phase grid connected voltage source inverters (VSI) play an important role in energy transformation systems . They are expected to be stable, robust and accurate during steady state as well as different grid faults and disturbances like voltage sags or unbalanced conditions. Caused by increasingly rising grid standards and efficiency requirements the use of multilevel inverter systems in grid connected low voltage applications are getting more and more attention. Nevertheless, the use of these inverter types leads to increased complexity of the control system and the hardware components. This thesis presents an improved control scheme for multilevel inverters in grid applications. The system combines a robust and high-dynamic direct current control scheme called scalar hysteresis En molts casos i, cada cop més, els sistemes de transformació energètica estan basats en convertidors en font de tensió connectats a la xarxa elèctrica trifàsica. Aquests convertidors necessiten de sistemes de control per controlar els fluxos energètics. Els sistemes de control han de ser estables, però també robustos i precisos durant el seu funcionament normal, però també en condicions on la xarxa pot presentar defectes, com curtcircuits, sots de tensió o desequilibris en la tensió. Degut a l'increment dels requeriments tècnics de connexió i d'eficiència energètica, els convertidors multinivell estan guanyant molt d'interès en aquest tipus d'aplicacions connectades a la xarxa tot i que el seu control i els seus components siguin més complexes. Aquesta tesi presenta un mètode de control per convertidors multinivell connectats a la xarxa elèctrica. El mètode combina la robustesa davant de canvis en el sistema així com una alta capacitat dinàmica per controlar el corrent injectat a la xarxa. El mètode presentat esta basat en l'anomenat Scalar Hysteresis Control (SHC) i incorpora un sistema feedforward que li permet seleccionar acuradament el punt de treball i seleccionar al millor estat de commutació en cada moment. La combinació del SHC amb el feedforward garanteix un comportament robust amb una alta dinàmica en totes les condicions de funcionament. El concepte bàsic del mètode feedforward proposat no usa sensors i està basat en detectar la tensió de l'inversor que inclou les components harmòniques. El mètode està basat en l'ús d'integradors generalitzats de segon ordre (second order generatlized integrators, SOGI) per tal de detectar les components harmòniques de la tensió de sortida de l'inversor. El sistema pot operar sense sensor de tensió, fins i tot en situacions de defecte de la tensió. Fins i tot, la informació extreta del SOGI es pot usar per altres llaços de control d'ordre superior com el control de la potencia usant les components simètriques. Per a determinar els millors estats de commutació de l'inversor amb el menor esforç s'usa en el mètode proposat en aquesta tesi un canvi de coordenades que usa valor enters. Aixo permet l'ús de relacions matemàtiques senzilles que es poden implementar fàcilment i que requereixen una menor potencia de càlcul. A més, el mètode és fàcilment generalitzable . En la tesi es presenten simulacions i resultats experimentals en convertidors multinivell de tres i cinc nivells per tal d'investigar i demostrar les funcionalitats del sistema de control proposat. Tant les simulacions com els resultats experimentals es realitzen en totes les condicions possibles de la xarxa elèctrica, estat estacionari, sots i distorsions harmòniques

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