Abstract:
A method for controlling a switching branch for a three-level converter, and a switching branch comprising a first semiconductor switch (S1) and a second semiconductor switch (S2), a first diode (D1) and a second diode (D2), a third semiconductor switch (S3) and a fourth semiconductor switch (S4), a third diode (D3), and a fourth diode (D4), a fifth semiconductor switch (S5) and a sixth semiconductor switch (S6), a fifth diode (D5), and a sixth diode (D6), and means (10) for controlling the semiconductor switches, wherein the first semiconductor switch (S1), the first diode (D1), the fifth semiconductor switch (S5) and the fifth diode (D5) reside in a first switching branch-specific semiconductor module (11), and the fourth semiconductor switch (S4), the fourth diode (D4), the sixth semiconductor switch (S6) and the sixth diode (D6) reside in a second switching branch-specific semiconductor module (12).
Abstract:
A method and arrangement in connection with a continuous material web, the material web running from an unwinder to a winder, at least one of the (un)winders being a centre winder, wherein the centre winder is controlled by an electric drive provided with a torque control. The method comprises giving an initial value for density of a material on the centre winder, calculating a moment of inertia for a roll of material on the centre winder, determining tightness of the material web by a mechanical sensor, producing, by a tightness controller, a correction term for torque calculation on the basis of a material web tightness reference, the determined material web tightness and the moment of inertia of the roll of material on (4) the centre winder, calculating a torque reference on the basis of the correction term produced by the tightness controller and the calculated moment of inertia of the roll of material (4) on the centre winder, and controlling the torque of the centre winder on the basis of the torque reference. The method comprises correcting the density value of the material on the centre winder on the basis of the correction term produced by the tightness controller.
Abstract:
An arrangement which comprises two or more energy storage units (1) for electrical energy connected in series, two or more balancing resistor units (2), each balancing resistor unit (2) connected in parallel with one of the energy storage units (1), means (3) for determining a voltage ( U tot ) over all of the series-connected energy storage units and means (3) for determining the energy storage unit voltages ( U cap ) between poles of the energy storage units (1). One or more of the balancing resistor units (2) comprise a base resistor unit (2.1) and a control resistor unit (2.2) connected in series and a switching device (2.3) connected in parallel with the control resistor units (2.2). The arrangement further comprises means (3) for determining reference voltages ( U ref ) for the energy storage units (1) on the basis of the voltage ( U tot ) over all of the series-connected capacitors and means (3) for controlling the switching device (2.3) to control the resistance of one or more of the balancing resistor units so that the energy storage unit voltage ( U cap ) of each energy storage unit (1) is maintained within a set range of the reference voltage ( U ref ) for each energy storage unit (1).
Abstract:
The invention relates to a mounting base (1) for an electric component (3), comprising: a first surface (2) for receiving the electric component (3), and for receiving a heat load generated by said electric component (3), and a second surface (4) for dissipating heat from said mounting base. In order to obtain good heat dissipation properties the mounting base comprises evaporator channels (7) arranged in the vicinity of said first surface (2), condenser channels (8) in the vicinity of said second surface (4) and a first and second connecting part (9, 10) for passing fluid between said condenser channels (8) and evaporator channels (7).
Abstract:
A method and an arrangement for controlling an inverter provided with a voltage intermediate circuit, the inverter (1) comprising two or more sub-inverters (1A,1B,1C), each being connected with a specific cable to feed a common load (2) and each sub-inverter (1A,1B,1C) receiving the same switch instruction pattern. The method comprises the steps of determining the magnitude of a time delay, and consecutively generating, with each sub-inverter (1A,1B,1C), an output voltage according to the switch instruction for the load (2) such that each sub-inverter generates an output voltage according to the switch instruction after a time equal to the time delay. The method prevents a load from being damaged by high rates of voltage rise supplied by the parallel connected inverters.
Abstract:
The present invention to an enclosure and method for providing a robust and inexpensive enclosure for protection against gun fire and high temperature variations, in which method an enclosure having an inner shell (5) and an outer shell (1) en-closing the inner shell (1) at a clearance thereof is formed, whereby a cavity is formed between the shells (1, 5). Electrical equipment is enclosed within the inner shell (5). Natural granular absorption material (4) is provided as the protective layer into the cavity on site upon installation of the enclosure.