Abstract: An electrical system forming part of a solar power plant is described. The electrical system includes a plurality of photovoltaic (PV) panels, a power converter, and a controller. In response to a detected electric arc on the DC side of the power converter, the controller is configured to enable a short circuit state of the power converter by controlling semiconductor switches of the power converter (e.g., turning on some or all of the semiconductor switches) to create a short circuit between DC input terminals of the power converter. The short circuit path though the power converter will extinguish the detected electric arc in the connected DC circuit.

Abstract: A power converter system is described. The power converter system includes a power converter comprising at least one converter unit, each converter unit comprising a plurality of semiconductor devices, each semiconductor device including at least a controllable semiconductor switch. A local controller is associated with at least one converter unit and adapted to receive CD and MD from a main controller. In response to a detected fault condition of the power converter system, the local controller is adapted to use at least one of the one or more locally-stored values to determine an operating state of the power converter system, and to use the determined operating state to select a fault operating procedure to control each associated converter unit according to the selected fault operating procedure without using any CD from the main controller.

Abstract: An electrical system forming part of a solar power plant is described. The electrical system includes a plurality of photovoltaic (PV) panels, a power converter, and a controller. In response to a detected electric arc on the DC side of the power converter, the controller is configured to enable a short circuit state of the power converter by controlling semiconductor switches of the power converter (e.g., turning on some or all of the semiconductor switches) to create a short circuit between DC input terminals of the power converter. The short circuit path though the power converter will extinguish the detected electric arc in the connected DC circuit.

Abstract: A power converter system is described. The system includes a power converter with a first converter including a plurality of semiconductor devices. Each semiconductor device includes at least a controllable semiconductor switch having a threshold voltage and a gate voltage for normal on-state conduction. The first converter has first and second DC terminals connected to a DC circuit, and a plurality of AC terminals. A controller is configured to supply current to the first converter (e.g., from an AC power source) and enable a short circuit state of the first converter by controlling semiconductor switches of the first converter to create at least one short circuit path through the first converter that carries the supplied current. At least one of the semiconductor switches in at least one of the short circuit paths is operated with modified on-state conduction in order to increase conduction losses.

Abstract: A method of short-circuiting a faulty submodule for a voltage-source power converter is disclosed. The submodule is based on a full-bridge, asymmetric full-bridge or half-bridge circuit design having power semiconductor switches with anti-parallel freewheeling diodes and optionally non-controllable semiconductor valves. The method 36 includes identifying a faulty semiconductor device and determining a failure mode selected from a short-circuit failure mode and an open circuit failure mode. The method further includes selecting a minimum number of power semiconductor switches suitable to provide a bypass path through the submodule depending on the identified faulty semiconductor device and the determined failure mode and driving the selected power semiconductor switches by a modified driving voltage compared to normal operation to cause them to break down in order to provide a durable, stable, low impedance short-circuit path between the AC voltage terminals of the submodule.

Abstract: A modular multipoint power converter for converting an AC voltage to a DC voltage or vice versa, and a method of operating it are provided. The multipoint power converter has a converter branches, whereby two converter branches are connected to each other respectively to form a phase branch of the converter. Each converter branch has a plurality of similar submodules, each of which is formed from a half-bridge circuit with power semiconductor switches. The branch currents through the converter branches are controlled in operation by increasing the DC component of the DC current or the DC intermediate circular current such that a unipolar current flows through the converter branches. As a result, with the same plurality of submodules per converter branch, the transmissible power can be increased, the power semi-conductor elements can be better utilized, or the plurality of submodules can be reduced while the transmissible power remains the same.

Abstract: A dual submodule is created for a modular multilevel converter, whereby the dual submodule has two interconnected submodules, whereby each submodule has an asymmetrical half-bridge circuit with two parallel bridge branches, which are connected between a first and a second terminal connection of the submodule, whereby each bridge branch is formed from a series circuit of a power semiconductor switch, and a diode, whereby the power semiconductor switch is allocated to an antiparallel free-wheeling diode, and has a capacitor, which is connected in parallel with the asymmetrical half-bridge circuit between the first and the second terminal connections of the module. The submodules are connected to each other via their AC terminals to form the dual submodule. Further, a modular multilevel converter is created, comprising a number of such dual submodules in each of its converter branches.

Abstract: A method (36) of short-circuiting a faulty submodule (12, 12?, 12?) for a voltage-source power converter (8) is disclosed. The submodule (12, 12?, 12?) is based on a full-bridge, asymmetric full-bridge or half-bridge circuit design having power semiconductor switches (T1-T4) with anti-parallel freewheeling diodes (D1-D4) and optionally non-controllable semiconductor valves (D1?-D4?). The method 36 includes identifying a faulty semiconductor device and determining a failure mode selected from a short-circuit failure mode and an open circuit failure mode.

Abstract: An inverter system is described. The inverter system includes a DC power source such as a plurality of photovoltaic (PV) panels, an inverter and a controller. The inverter includes a plurality of semiconductor devices (e.g., controllable semiconductor switches such as IGBTs and anti-parallel connected diodes) arranged in a suitable inverter topology. The inverter includes DC input terminals connected to the PV panels by means of a DC link and at least one AC output terminal. When starting the inverter, the controller is configured to enable a short circuit state of the inverter by controlling the semiconductor switches to create a short circuit between the DC input terminals such that the inverter carries a current substantially equal to the short circuit current of the PV panels.

Abstract: A double submodule for a modular multilevel converter comprising a first and second submodule coupled to the first. Each submodule comprises an asymmetric H bridge circuit with two parallel bridges branches, connected between a first and a second direct voltage node of the submodule. Each bridge branch is formed by a series connection from a controllable power semiconductor switch and a diode. A storage capacitor is connected in parallel to the asymmetric H bridge circuit between the first and the second direct voltage node of the submodule. The first and the second submodule are interconnected in such a way that a power semiconductor switch or a diode is part of a bridge branch of the first submodule as well as part of a bridge branch of the second submodule. A modular multilevel converter, comprises a series connection of such double submodules in each of its converter branches, is also disclosed.

Abstract: A modular multipoint power converter (8) for converting an AC voltage to a DC voltage or vice versa, and a method of operating such a modular multipoint power converter are provided. The multipoint power converter has a plurality of converter branches (9a-f), whereby two converter branches (9a-b, 9c-d, 9e-f) are connected to each other respectively to form a phase branch 11a-c of the converter (8). Each converter branch has a number of similar submodules (14, 14?), each of which is formed from a half-bridge circuit (18) with power semiconductor switches (T1-T4). The branch currents iq(t) through the converter branches (9a-f) are controlled in operation by increasing the DC component (Ig) of the DC current or the DC intermediate circular current (Idc) such that a unipolar current, preferably a continuous unipolar sinusoidal current, flows through the converter branches (9a-f).

Abstract: An inverter system (1) is described. The inverter system (1) includes a DC power source such as a plurality of photovoltaic (PV) panels (8), an inverter (2) and a controller (32). The inverter (2) includes a plurality of semiconductor devices (e.g., controllable semiconductor switches such as IGBTs and anti-parallel connected diodes) arranged in a suitable inverter topology. The inverter (2) includes DC input terminals (4) connected to the PV panels (8) by means of a DC link (10) and at least one AC output terminal (6). When starting the inverter (2), the controller (32) is configured to enable a short circuit state of the inverter (2) by controlling the semiconductor switches to create a short circuit between the DC input terminals (4) such that the inverter (2) carries a current substantially equal to the short circuit current of the PV panels (8).

Abstract: A method and a device for controlling a commutation process of a load current between two switching modules are disclosed that each have a MOSFET that can be controlled by a gate-source voltage, and an intrinsic-body inverse diode. To reduce oscillations in the down-commutation of the inverse diodes caused by parasitic circuit parameters, after switching off one of the switching modules, the gate-source control voltage applied to this switching module is temporarily switched off until being increased again the vicinity of the threshold voltage for switching on the MOSFET, before and while the other switching module is switched on, in order to commutate the current from the inverse diode of the one switching module to the MOSFET of the other switching module.

Abstract: A switch module and a converter developed with the help of a switch module. The switch module presents two series connections comprising a power semi-conductor switch and a diode and. Parallel to the first series connection a first capacitor is connected. Between the first capacitor and the second series connection at least one intermediate connection is connected. This is designed as quadripole, whereby between both the output connections a second capacitor is connected. The first output connection is connected through a third power semi-conductor switch with the first input connection. The second output connection is connected with the cathode of a third diode, whose anode is connected with the second input connection of the intermediate circuit. With this switch module at least five voltage levels can be set up for an output voltage. For each additionally present intermediate circuit the number of the possible voltage levels increases by two.

Abstract: A device (2) for the on-demand commutation of an electrical current from a first line branch (14, 3; 36) to another, second line branch (4; 41; 71) is created, which has a number of power semiconductor switching elements (7; 47; 53), which are arranged in series and/or parallel to one another in the second line branch (4; 41; 71), and a control unit (18; 51) for controlling the number of power semiconductor switching elements (7; 47; 53). The control unit (18; 51) is adapted to apply to each of the number of power semiconductor switching elements (7; 47; 53) an increased control voltage (VGE) whose level is above the maximum permissible control voltage specified for continuous operation, in order to switch on or maintain the conduction of the number of power semiconductor switching elements and to cause an increased current flow through it, whose current rating is at least double the nominal operating current.

Abstract: A method and a device for controlling a voltage-controlled power semiconductor switch that can be switched off again, which has a first and a second connection and a control connection and which is conductive in the switched on state between the first and the second connection is provided. Firstly, a first control voltage comprising a first value is applied to the control connection to switch on the power semiconductor switch. Subsequently, conditions are detected, which indicate the progress of the switch-on procedure of the power semiconductor switch. As soon as conditions are detected, which are indicative of the fact that the switch-on procedure is deemed to be complete, a second control voltage comprising a second value higher than the first value is applied to the control connection to operate the power semiconductor switch in the conductive state with a higher control voltage to reduce its conduction losses.

Abstract: A method and a device for controlling a commutation process of a load current between two switching modules are disclosed that each have a MOSFET that can be controlled by a gate-source voltage, and an intrinsic-body inverse diode. To reduce oscillations in the down-commutation of the inverse diodes caused by parasitic circuit parameters, after switching off one of the switching modules, the gate-source control voltage applied to this switching module is temporarily switched off until being increased again the vicinity of the threshold voltage for switching on the MOSFET, before and while the other switching module is switched on, in order to commutate the current from the inverse diode of the one switching module to the MOSFET of the other switching module.

Abstract: A dual submodule is created for a modular multilevel converter, whereby the dual submodule has two interconnected submodules, whereby each submodule has an asymmetrical half-bridge circuit with two parallel bridge branches, which are connected between a first and a second terminal connection of the submodule, whereby each bridge branch is formed from a series circuit of a power semiconductor switch, and a diode, whereby the power semiconductor switch is allocated to an antiparallel free-wheeling diode, and has a capacitor, which is connected in parallel with the asymmetrical half-bridge circuit between the first and the second terminal connections of the module. The submodules are connected to each other via their AC terminals to form the dual submodule. Further, a modular multilevel converter is created, comprising a number of such dual submodules in each of its converter branches.

Abstract: A method and a device for controlling a voltage-controlled power semiconductor switch that can be switched off again, which has a first and a second connection and a control connection and which is conductive in the switched on state between the first and the second connection is provided. Firstly, a first control voltage comprising a first value is applied to the control connection to switch on the power semiconductor switch. Subsequently, conditions are detected, which indicate the progress of the switch-on procedure of the power semiconductor switch. As soon as conditions are detected, which are indicative of the fact that the switch-on procedure is deemed to be complete, a second control voltage comprising a second value higher than the first value is applied to the control connection to operate the power semiconductor switch in the conductive state with a higher control voltage to reduce its conduction losses.

Abstract: A double submodule for a modular multilevel converter comprising a first and second submodule coupled to the first. Each submodule comprises an asymmetric H bridge circuit with two parallel bridges branches, connected between a first and a second direct voltage node of the submodule. Each bridge branch is formed by a series connection from a controllable power semiconductor switch and a diode. A storage capacitor is connected in parallel to the asymmetric H bridge circuit between the first and the second direct voltage node of the submodule. The first and the second submodule are interconnected in such a way that a power semiconductor switch or a diode is part of a bridge branch of the first submodule as well as part of a bridge branch of the second submodule. A modular multilevel converter, comprises a series connection of such double submodules in each of its converter branches, is also disclosed.