Integration of a lithium-ion battery in a micro-photovoltaic system: Passive versus active coupling architectures

A balcony photovoltaic (PV) system, also known as a micro-PV system, is a small PV system consisting of one or two solar modules with an output of 100–600 Wp and a corresponding inverter that uses standard plugs to feed the renewable energy into the house grid. In the present study we demonstrate the integration of a commercial lithium-ion battery into a commercial micro-PV system. We firstly show simulations over one year with one second time resolution which we use to assess the influence of battery and PV size on self-consumption, self-sufficiency and the annual cost savings. We then develop and operate experimental setups using two different architectures for integrating the battery into the micro-PV system. In the passive hybrid architecture, the battery is in parallel electrical connection to the PV module. In the active hybrid architecture, an additional DC-DC converter is used. Both architectures include measures to avoid maximum power point tracking of the battery by the module inverter. Resulting PV/battery/inverter systems with 300 Wp PV and 555 Wh battery were tested in continuous operation over three days under real solar irradiance conditions. Both architectures were able to maintain stable operation and demonstrate the shift of PV energy from the day into the night. System efficiencies were observed comparable to a reference system without battery. This study therefore demonstrates the feasibility of both active and passive coupling architectures

A monoclinic polymorph of di-μ-oxido-bis­({2-[2-(methyl­amino)ethyl­imino­methyl]phenolato-κ3 N,N′,O}oxidovanadium(V))

A new monoclinic polymorph of the title compound, [V2(C10H13N2O)2O4], which is a centrosymmetric dimer, crystallizes in space group P21/c, whereas the previously known polymorph crystallizes in the ortho­rhom­bic space group Pbca [Mokry & Carrano (1993 ▶). Inorg. Chem. 32, 6119–6121]. Each VV atom is six-coordinated by one oxide group, two N atoms and one O atom from the Schiff base ligand, and by two additional bridging O atoms. The two methyl­ene groups are each disordered over two sites, with occupancy factors of 0.776 (14) and 0.224 (14). In the crystal structure, there are C—H⋯O hydrogen bonds and C—H⋯π inter­actions between the dimers

Di-μ-oxido-bis­({2-[(R,R)-(−)-(2-amino­cyclo­hexyl)imino­meth­yl]-4-nitro­phenolato-κ3 N,N′,O}oxidovanadium(V)) dimethyl sulfoxide disolvate

The title compound, [V2(C13H16N3O3)2O4]·2C2H6OS, is a centrosymmetric dimeric complex solvated by two dimethyl sulfoxide mol­ecules. Each VV atom is six-coordinated by one oxide group, two N atoms and one O atom from the tridentate Schiff base ligand, and by two additional bridging O atoms in a distorted octa­hedral coordination geometry. Three atoms of the cyclo­hexane ring are each disordered over two sites, with occupancy factors of 0.501 (10) and 0.499 (10). C—H⋯O and N—H⋯O hydrogen bonds link the dimers and solvent mol­ecules into a supra­molecular network

Is it necessary to use a current state controller in a pulse width modulated ac drive?

Im vorliegenden Beitrag werden verschiedene Methoden für den Entwurf eines Stromreglers für pulsweitenmoduliert betriebene Drehstromantriebe beschrieben und miteinander verglichen. In den Vergleich eingeschlossen sind sowohl zeitkontinuierlich entworfene PI-Regler mit klassischer Entkopplung als auch zeitdiskret entworfene PI-Regler mit weiterentwickelter Entkopplung und zeitdiskret entworfene Zustandsregler. Der Fokus liegt dabei auf der Entkopplung der d- und q-Komponente des Statorstromraumzeigers, auch bei hoher Statorfrequenz oder geringer Schaltfrequenz. Es wird gezeigt, dass die Heranziehung von zeitdiskreten Motormodellen und ein darauf basierender Reglerentwurf mit größer werdendem Quotient aus Statorfrequenz und Schaltfrequenz zunehmend Vorteile bietet.In this paper several methods for designing a current controller for ac drives are presented and compared to. The main focus of the comparison is the decoupling level of the d- and q-components of the stator current space vector. It will be shown that the best approach is to create a time-discrete motor model and base the control algorithm on it. The article enters additionally into the question, if a current state controller is necessary or not

Di-μ-oxido-bis({(R)-(–)-2-[1-(2-aminopropylimino)ethyl]-1-naphtholato-κ3N,N′,O}oxidovanadium(V))

In the title dinuclear compound, [V2(C15H17N2O)2O4], each VV atom is six-coordinated by one oxide group, and by two N and one O atom of the tridentate Schiff base ligand, and bridged by two additional oxide O atoms, resulting in a centrosymmetric dimer. The metal centre has a distorted octahedral coordination with the monoanionic Schiff base ligand occupying one equatorial and two axial coordination positions. The separation between V atoms is 3.214 (3) Å. In the crystal structure, there are N—H...O, C—H...O and C—H...À hydrogen bonds, and À–À interactions