Abstract: A method for controlling a modular multilevel power converter which has at least one phase module branch with a series circuit of modules. Each of the modules has an energy storage device and a power semiconductor circuit with electronic switching elements. A duty cycle of the phase module branch is ascertained, wherein the duty cycle describes the ratio between the voltage which is being output by the phase module branch and the voltage which can be maximally output by the phase module branch. The maximum value of the duty cycle during a preselected time period is ascertained, and the maximum value of the duty cycle is controlled to a target value for the maximum value of the duty cycle by a controller.

Abstract: A method manages a fault on a DC voltage side of a converter assembly including a modular multistage converter with switching modules having semiconductor switches and an energy store. Some switching modules are a first type and others are a second type. During operation, a positive switching module voltage, negative switching module voltage or zero voltage are generated at terminals of switching modules of the first type, and a positive switching module voltage or zero voltage are generated at terminals of switching modules of the second type. Upon detecting a DC voltage side fault, switching modules of the first type are actuated such that the polarity of their energy store voltages corresponds to the polarity of a fault current, and energy stores of switching modules of the first type are charged to a voltage exceeding their rated voltage. A converter assembly carrying out the method is also provided.

Abstract: When the strip head (7) of a metal strip (1) runs out of a roll stand (2a), a lateral position (y) of the strip head (7) is detected by a detection device (8) at at least one location (P) lying between the roll stand (2a) and a device (8) arranged downstream of the roll stand. A strip position controller (10) is designed as a model predictive controller which ascertains a sequence of adjusting commands (uk) to be output one after the other in a work cycle (T) on the basis of the detected lateral position (y) of the strip head (7), and the sequence is used to adjust a respective roll gap wedge. The number of control commands (uk) define a prediction horizon (PH) of the strip position controller (10) in connection with the work cycle (T). The strip position controller (10) at least supplies the roll stand (2a) with the control command (u0) ascertained to be output next.

Abstract: A method manages a fault on a DC voltage side of a converter assembly including a modular multistage converter with switching modules having semiconductor switches and an energy store. Some switching modules are a first type and others are a second type. During operation, a positive switching module voltage, negative switching module voltage or zero voltage are generated at terminals of switching modules of the first type, and a positive switching module voltage or zero voltage are generated at terminals of switching modules of the second type. Upon detecting a DC voltage side fault, switching modules of the first type are actuated such that the polarity of their energy store voltages corresponds to the polarity of a fault current, and energy stores of switching modules of the first type are charged to a voltage exceeding their rated voltage. A converter assembly carrying out the method is also provided.

Abstract: A hydraulic cylinder unit (1) having a hydraulic cylinder (2), a piston (3) which can be moved in the hydraulic cylinder (2), and a servo valve (7). The piston (3) separates working volumes (5A, 5B) of the hydraulic cylinder unit (1) from one another. The servo valve (7) is connected to a hydraulic pump (8), a tank (9), and the working volumes (5A, 5B). The servo valve (7) is supplied with a pump pressure (pP) via the hydraulic pump (8). The tank (9) has a tank pressure (pT). The servo valve (7) is adjusted to a defined valve position (y). A piston position (z) of the piston (3) in the hydraulic cylinder (2) and working pressures (pA, pB) which are applied to the working volumes (5A, 5B) are detected.

Abstract: When the strip head (7) of a metal strip (1) runs out of a roll stand (2a), a lateral position (y) of the strip head (7) is detected by a detection device (8) at at least one location (P) lying between the roll stand (2a) and a device (8) arranged downstream of the roll stand. A strip position controller (10) is designed as a model predictive controller which ascertains a sequence of adjusting commands (uk) to be output one after the other in a work cycle (T) on the basis of the detected lateral position (y) of the strip head (7), and the sequence is used to adjust a respective roll gap wedge. The number of control commands (uk) define a prediction horizon (PH) of the strip position controller (10) in connection with the work cycle (T). The strip position controller (10) at least supplies the roll stand (2a) with the control command (u0) ascertained to be output next.

Abstract: A hydraulic cylinder unit (1) having a hydraulic cylinder (2), a piston (3) which can be moved in the hydraulic cylinder (2), and a servo valve (7). The piston (3) separates working volumes (5A, 5B) of the hydraulic cylinder unit (1) from one another. The servo valve (7) is connected to a hydraulic pump (8), a tank (9), and the working volumes (5A, 5B). The servo valve (7) is supplied with a pump pressure (pP) via the hydraulic pump (8). The tank (9) has a tank pressure (pT). The servo valve (7) is adjusted to a defined valve position (y). A piston position (z) of the piston (3) in the hydraulic cylinder (2) and working pressures (pA, pB) which are applied to the working volumes (5A, 5B) are detected.