Abstract: A method and a converter for controlling a multi-phase electric machine are disclosed. Each phase voltage of the electric machine is generated with two electronic switches interconnected to form a half bridge. The switching statuses of the half bridges are controlled with space vector modulation. A minimum dwell time is predefined, and each switching status, represented by an active basic voltage space vector, of the half bridges is maintained at least for the minimum dwell time.

Abstract: A power distributing apparatus connecting several loads to a DC voltage supply includes a number of cascaded hierarchy stages connected between the DC voltage supply and the loads. The hierarchy stages define a radial-network-type current path which branches into a number of parallel sub-paths with each additional hierarchy stage. The number of sub-paths connecting the loads corresponds to the number of connected loads. Each sub-path conducts an electric current which can be switched by a respective circuit breaker disposed in each sub-path. The value of a trigger current for each circuit breaker in each hierarchy stage increases successively from the load side toward the DC voltage supply side.

Abstract: A neutral point clamped inverter with an upper half-bridge and a lower half-bridge, wherein each half-bridge has an inner transistor and an outer transistor, where the inner transistor of the upper half-bridge is configured to interact with the outer transistor of the upper half-bridge such that a signal that reproduces the switch state of the inner transistor is coupled into an actuation circuit for switching the outer transistor and influences the switch state of the outer transistor.

Abstract: In a method for controlling a direct current switch having first and second semiconductor switches capable of being switched off, the first and second semiconductor switches are arranged between first and second terminals to enable conduction of a current with a first polarity through the first semiconductor switch and conduction of the current with a second polarity that is opposite to the first polarity through the second semiconductor switch. One of the first and second semiconductor switches is switched off as a function of a current measurement value.

Abstract: An electronic switch for a DC voltage system includes at least two turn-off semiconductor switches, a varistor and a capacitor, and at least two diodes connected in series with opposite polarity. The turn-off semiconductor switches are connected at a connection point in series with opposite polarity between a first connection of the electronic switch and a second connection of the electronic switch. In order to provide improved overvoltage protection, the varistor and the capacitor form a series connection, with one end of the series connection connected to the connection point. A DC voltage system employing the electronic switch and a method for limiting overvoltages in the electronic switch or in a corresponding DC voltage system are also disclosed. Inductive energy of an element connected to the electronic switch is transferred to the capacitor when a limit, defined by the varistor, has been exceeded.

Abstract: A dangerous, higher-frequency (>1 kHz) earth fault current in an electrical drive system operated in an electrical grid and having a power converter and an electrical drive machine can be prevented by producing a common-mode voltage with a defined common-mode voltage component in the power converter at a selected low frequency (<1 kHz); in the event of an earth fault in the electrical drive system, flowing at the selected low frequency a common-mode current component of a common-mode current through a predominantly ohmic conductor-to-earth impedance on the basis of the defined common-mode voltage component; measuring a total common-mode current in one of several current circuits of the electrical drive system; determining from the total current the common-mode current component; and when the common-mode current component reaches a reference value, disconnecting the electrical drive system from the electrical grid.

Abstract: A method for locating a ground fault in an IT network which has a converter with a rectifier connected to a power transmission network, a DC link and an inverter connected to an electrical machine includes measuring a common-mode voltage property of the converter or of the power transmission network and comparing the common-mode voltage property with an output voltage property of an output voltage of the inverter. When the IT network experiences a ground fault, the comparison of the common-mode voltage property with the output voltage property is used to determine whether a machine area of the IT network connected downstream of the converter, which includes the electrical machine and a connecting line between the electrical machine and the converter, causes the ground fault.

Abstract: A direct-current network has an infeed unit, a plurality of network sections which are each separably inter connected by respective switching elements, and a controllable current-limiting unit, which limits charge-transfer currents that flow between the network sections because of different voltages of the network sections following disconnection of the network sections from the infeed unit and before reconnection of the network sections to the infeed unit.

Abstract: In a method for controlling a direct current switch having first and second semiconductor switches capable of being switched off, the first and second semiconductor switches are arranged between first and second terminals to enable conduction of a current with a first polarity through the first semiconductor switch and conduction of the current with a second polarity that is opposite to the first polarity through the second semiconductor switch. One of the first and second semiconductor switches is switched off as a function of a current measurement value.

Abstract: A power distributing apparatus connecting several loads to a DC voltage supply includes a number of cascaded hierarchy stages connected between the DC voltage supply and the loads. The hierarchy stages define a radial-network-type current path which branches into a number of parallel sub-paths with each additional hierarchy stage. The number of sub-paths connecting the loads corresponds to the number of connected loads. Each sub-path conducts an electric current which can be switched by a respective circuit breaker disposed in each sub-path. The value of a trigger current for each circuit breaker in each hierarchy stage increases successively from the load side toward the DC voltage supply side.

Abstract: The invention relates to an electrical DC voltage system which is coupled to at least one AC voltage network (1). A supply circuit (5) is used to convert three-phase AC voltage into DC voltage which supplies a DC voltage system. The latter contains devices (13, 14, 21, 23, 27, 22, 17, 19, 20) each having a decentralized precharge device (7). The invention also relates to a method for operating such an electrical DC voltage system on the basis of a voltage value applied to the busbar (12).

Abstract: In a method for operating an inverter system and a corresponding inverter system, which includes from the network filter to the inverter, values are determined using the data unit, and a value spectrum of the determined values is determined using an evaluation unit. The value spectrum is compared to a predetermined or predefinable limit spectrum using an assessment unit, and a switching frequency of the inverter can be adapted while in operation by using an adapter unit arranged downstream of the data unit, the evaluation unit and the assessment unit in the return path.

Abstract: A dangerous, higher-frequency (>1 kHz) earth fault current in an electrical drive system operated in an electrical grid and having a power converter and an electrical drive machine can be prevented by producing a common-mode voltage with a defined common-mode voltage component in the power converter at a selected low frequency (<1 kHz); in the event of an earth fault in the electrical drive system, flowing at the selected low frequency a common-mode current component of a common-mode current through a predominantly ohmic conductor-to-earth impedance on the basis of the defined common-mode voltage component; measuring a total common-mode current in one of several current circuits of the electrical drive system; determining from the total current the common-mode current component; and when the common-mode current component reaches a reference value, disconnecting the electrical drive system from the electrical grid.

Abstract: In a method for operating an inverter system and a corresponding inverter system, which includes from the network filter to the inverter, values are determined using the data unit, and a value spectrum of the determined values is determined using an evaluation unit. The value spectrum is compared to a predetermined or predefinable limit spectrum using an assessment unit, and a switching frequency of the inverter can be adapted while in operation by using an adapter unit arranged downstream of the data unit, the evaluation unit and the assessment unit in the return path.

Abstract: In a frequency converter operated for safety of personnel and/or fire protection via a ground fault interrupter is frequently not able to distinguish between an actual fault current and an operationally generated leakage current. The proposed method addresses this problem by determining a course of a magnitude of a current flowing through the frequency converter, predefining a signal portion which is independent of switching processes within the frequency converter while the frequency converter operates fault-free, checking whether the determined course satisfies a criterion that is predetermined depending on the signal portion, and interrupting the current the determined course fails to satisfy the predetermined criterion.

Abstract: A conventional ground fault interrupter in an arrangement with a frequency converter and electrical machines may be accidentally tripped due to operation-related leakage currents. This can be prevented by operating a ground fault interrupter for a frequency converter receiving a mains current in the following manner: receiving switching information about switching operations in the frequency converter, measuring a signal associated with a common mode current in a power line device which conducts the mains current to the frequency converter, determining, based on the switching information, an expected signal expected for the common mode current produced by the switching operations, identifying, based on the measured signal and the expected signal, a fault current, and interrupting the mains power depending on the identified fault current. A ground fault interrupter is hereby provided with an evaluation unit configured to carry out the method.

Abstract: The invention relates to a lossy triphase low-pass filter having a filter choke, a filter capacitor, and an attenuation element per phase of said the low-pass filter, wherein one filter capacitor and one attenuation element each are electrically connected in series. Two diodes are provided as attenuation elements, which are electrically connected to each other in an anti-parallel manner. In this manner a lossy triphase low-pass filter is obtained, the power loss of which is significantly reduced without any loss of the attenuation effect.

Abstract: In a frequency converter operated for safety of personnel and/or fire protection via a ground fault interrupter is frequently not able to distinguish between an actual fault current and an operationally generated leakage current. The proposed method addresses this problem by determining a course of a magnitude of a current flowing through the frequency converter, predefining a signal portion which is independent of switching processes within the frequency converter while the frequency converter operates fault-free, checking whether the determined course satisfies a criterion that is predetermined depending on the signal portion, and interrupting the current the determined course fails to satisfy the predetermined criterion.

Abstract: A conventional ground fault interrupter in an arrangement with a frequency converter and electrical machines may be accidentally tripped due to operation-related leakage currents. This can be prevented by operating a ground fault interrupter for a frequency converter receiving a mains current in the following manner: receiving switching information about switching operations in the frequency converter, measuring a signal associated with a common mode current in a power line device which conducts the mains current to the frequency converter, determining, based on the switching information, an expected signal expected for the common mode current produced by the switching operations, identifying, based on the measured signal and the expected signal, a fault current, and interrupting the mains power depending on the identified fault current. A ground fault interrupter is hereby provided with an evaluation unit configured to carry out the method.

Abstract: In one embodiment, a method for determining the distance of a conducting surface profiled in a direction of distance determination from a functional surface moving relative to the profiled surface is disclosed. The method includes connecting inputs of a sensor to an oscillator arrangement. The sensor includes a first and a second measuring coil. The method includes further connecting outputs of the sensor to an analog-to-digital converter via a demodulator unit to obtain first and second digital measured values. The first and second digital measured values correspond to the distance between the profiled surface and the first and second measuring coil of the sensor, respectively. The method further includes connecting an arithmetic unit to the analog converter unit. The second measurement coil is arranged at a known distance from the first measuring coil on the side of the first measuring coil that faces away from the profiled surface.