Siemens Aktiengesellschaft

Harald Wiessmann

Norbert Benesch

Bernd Dressel

Maximilian Schmitt

Franz Bauer

Bernd Herrmann

Michael Götzelmann

In a method for operating a self-commutated inverter, a direct voltage is supplied from a direct voltage circuit to electronic switches, which are controlled in an open-loop manner by space vector modulation, for generating a three-phase output voltage. The three-phase output voltage is supplied to a three-phase output filter arranged downstream of the electronic switches and coupled to the direct voltage circuit, allowing common mode portions of filter input currents of the output filter to flow into the direct voltage circuit. Filter output currents of the three-phase output filter are controlled in a closed-loop manner, and a zero-system voltage of the filter input voltages of the output filter is controlled in a closed loop manner as a function of a target voltage space vector of the space vector modulation and as a function of the filter input currents to suppress oscillations in a zero system of the filter input currents.

Self-commutated inverter and operation of same

In a method for operating an energy converter that couples a first supply network to a second supply network by converting electrical energy via a switch element, the switch element is operated in a switching operation and a supply-network current for one of the supply networks is adjusted depending on a comparison of the supply-network current with a reference current. In a first operating mode for the switching operation, an electrical voltage of one of the supply networks is set by a PWM method on the basis of the comparison, and a second operating mode is provided, in which the switch element is switched when, during the comparison, a difference between the supply-network current and the reference current is greater than a first predefined relative switching value and/or is smaller than a second predefined relative switching value, wherein the first and second operating modes are alternated during the operation.

Electrically coupling a first electrical supply network to a second electrical supply network

A converter feeds phase currents into phase lines by applying alternately a high and a low potential via phase units. The phase currents are supplied via a filter device arranged downstream of the converter, with a portion of the filter currents supplied to filter capacitors connected to the phase lines, and feeds the remaining parts of the phase currents supplied to an electric load. The control device accepts the phase currents. A regulating device determines control signals for the phase units by direct-current control, such that a voltage profile downstream of the filter device has a predetermined amplitude when and as long as the supplied phase currents have minimum spacing from a predetermined maximum value. Otherwise, the control device intervenes in the control of the phase units by limiting the phase currents to the maximum value, until the voltage profile downstream of the filter device regains the predetermined amplitude.

Short-circuit-proof inverter having a direct current control

Disclosed is a method for controlling phase currents of a plurality of three-phase inverters connected in parallel. The phase currents of each inverter are controlled by direct hysteresis current control wherein an actual current space vector for actual values of the phase currents of each inverter is maintained about a target current space vector within a hysteresis window. The measured current space vector of a first inverter is formed by all three phase currents of the first inverter. The actual current space vector of each additional inverter is formed from exactly two phase currents of the respective additional inverter under the proviso that all three phase currents of the additional inverters add up to zero. The selection of the two phase currents from which the actual current space vector is formed, is varied.

Control of phase currents of inverters that are connected in parallel

A method for regulating an AC output current of a converter having a DC voltage intermediate circuit and a semiconductor switch in a bridge circuit for converting a DC voltage of the DC voltage intermediate circuit into an AC output current. The AC output current is regulated by way of a direct hysteresis current regulation, in which an actual value of the AC output current is maintained within a hysteresis window around a set point value. Furthermore, a hysteresis width of the hysteresis window is modulated in order to adjust a frequency spectrum of the AC output current.

Regulation of an output current of a converter

The invention relates to a method for controlling phase currents (iU_WR, iv_WR, iw_WR) of a three-phase inverter (WR), the phase currents (iU_WR, iv_WR, iw_WR) of the inverter (WR) being controlled by way of a direct hysteresis current control and a selected phase of the inverter (WR) being additionally switched depending on a zero system current (i_WR) of the inverter (WR).

Control of phase currents of an inverter

For operating multi-axis drive assemblies more reliably even in a field weakening range, a current conversion device is proposed which includes a voltage-source DC link, a plurality of inverters having each a DC input side connected to the voltage-source DC link and AC output-side terminals for connection to an electric motor, and a control device configured to short-circuit each of the inverters. A measurement device measures an electrical variable at each of the inverters. The control device determines based on the measured electrical variables independently for each of the inverters directly or indirectly whether a particular inverter is feeding energy into the voltage-source DC link, and short-circuits, when this is the case, the particular inverter independently of the other inverters. A corresponding operating method is also disclosed.

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Erlangen, Germany

Harald Wiessmann