Abstract: System to set up an autonomous temporary solar farm, comprising a multitude of photovoltaic power modules (1, 1?, 1?) and a multitude of battery modules (2, 2?, 2?), wherein the photovoltaic power modules (1, 1?, 1?) and the battery modules (2, 2?, 2?) each comprise compatible electrical DC connectors (3, 3?), so that the battery modules (2, 2?, 2?) can be electrically connected to and charged by the photovoltaic power modules (1, 1?, 1?), wherein the system comprises at least one magazine (4) adapted to hold both the photovoltaic power modules (1, 1?, 1?) and the battery modules (2, 2?, 2?), at least one robotic vehicle (5) comprising a holding platform (6) to hold the magazine (4), and a manipulator mechanism (8) that is adapted to extract a photovoltaic power module (1, 1?, 1?) and/or a battery module (2, 2?, 2?) from the magazine (4) and place it on a ground surface, and/or pick up a photovoltaic power module (1, 1?, 1?) and/or a battery module (2, 2?, 2?) from a ground surface and insert it into the maga

Abstract: Electric motor, in particular induction motor, comprising a stator, a rotor and a control device which is arranged at the rotor. The three rotor windings are connected to a Rotor Control device with inverter and controller unit mounted on the rotor. A capacitor is placed in the DC link. The capacitor is supplied from the EMF induced in the rotor. The current in the rotor windings is advanced in order to achieve a 90 degree phase shift between rotor current and stator MMF vector. To achieve this the frequency and amplitude of the rotor current as well as the phase shift can be varied. Wherein the frequency of the rotor inverter is matching the slip frequency.

Abstract: Electric motor, in particular induction motor, comprising a stator, a rotor and a control device which is arranged at the rotor. The three rotor windings are connected to a Rotor Control device with inverter and controller unit mounted on the rotor. A capacitor is placed in the DC link. The capacitor is supplied from the EMF induced in the rotor. The current in the rotor windings is advanced in order to achieve a 90 degree phase shift between rotor current and stator MMF vector. To achieve this the frequency and amplitude of the rotor current as well as the phase shift can be varied. Wherein the frequency of the rotor inverter is matching the slip frequency.