Abstract: A power converter system includes auxiliary resonant commutated pole converter legs, particularly ARCP half-bridge legs, connected in parallel between a common dc system and a common ac system or between two common dc systems. Commutations of the parallel-connected converter legs are initiated by simultaneous commutation commands. A control arrangement is provided to balance a current sharing between the parallel-connected ARCP converter legs by means of having an individual autonomous leg-specific boost current adjustment for each of the parallel-connected ARCP converter legs for adjusting boost currents in a direction that a differential output current is reduced. Each individual boost current adjustment is dependent on the magnitude of the leg current of the respective ARCP converter leg only.

Abstract: Current sharing between the plurality of parallel-connected ARCP or hard-switching converter legs is balanced by a control arrangement. The control arrangement senses a leg output current in each of the parallel-connected converter legs and have an individual autonomous leg-specific switching instant adjustment for the main switches of each of the parallel-connected converter legs to shift the first mode A commutation of the respective converter leg later in time and to shift the second mode B commutation of the respective converter leg earlier in time by a variable timestep proportional to the value of the sensed leg current of the respective converter leg. In other words, if the value of the sensed leg output current in one converter leg is larger than in the other converter leg, then in mode A, the higher-current leg will commutate later than the leg with less current, and in mode B, the higher-current leg will commutate earlier than the leg with less current.

Abstract: A power converter system including an auxiliary resonant commutated pole converter leg, particularly an ARCP half-bridge, and a resonant swing time controller for the ARCP converter leg. The resonant swing time controller is configured to control a resonant swing time duration of ARCP commutations to a reference value of the resonant swing time by means of a closed loop feedback of an actual resonant swing time duration. In an embodiment, the resonant swing time controller is configured to provide, based on an error between the actual resonant swing time duration and the reference value, control values to adjust a turn-on instant of at least one auxiliary switching device of the ARCP converter leg earlier or later in time so that resonant swing time duration of ARCP commutations is controlled towards the reference value.

Abstract: A power converter system includes an auxiliary resonant commutated pole converter leg, particularly an ARCP half-bridge, having a series connection of a saturable-core inductor and at least one bi-directional auxiliary switch connected to a dc-link neutral point. An ARCP controller is provided to control turn-on of the at least one bi-directional auxiliary switch to provide an auxiliary current flowing through the saturable-core inductor, and a saturation instant detector is provided to detect a saturation instant of the saturable-core inductor due to the auxiliary current exceeding a saturation current after turn-on of the at least one bidirectional auxiliary switch. The ARCP controller is responsive the detector to continue providing the auxiliary current and thereby a boost current for a predetermined boost period after the detected saturation instant of the saturable-core inductor to achieve a desired total boost current.

Abstract: A power inverter system includes switching mode inverter legs connected in parallel between a common DC input and, via leg output inductors, a common phase output to feed a phase output current to a common load. The commutations of the parallel-connected inverter legs are initiated by essentially simultaneous commutation commands. The leg output current is sensed before and after a commutation in each of the parallel-connected inverter legs to obtain a pre-commutation current value and a post-commutation current value. Alternatively, a voltage pulse over the leg output inductor is sensed in each of the parallel-connected inverter legs during the commutation.

Abstract: A method for controlling a three-level brake chopper and a three-level brake chopper including, a first controllable semiconductor switch connected between a positive direct current pole and a first connection point, a second controllable semiconductor switch connected between the first connection point and a neutral direct current pole, a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point, a fourth controllable semiconductor switch connected between the second connection point and a negative direct current pole, resistance means connected between the first connection point and the second connection point, and control means configured to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the resistance means.

Abstract: A method for controlling a three-level brake chopper and a three-level brake chopper including, a first controllable semiconductor switch connected between a positive direct current pole and a first connection point, a second controllable semiconductor switch connected between the first connection point and a neutral direct current pole, a third controllable semiconductor switch connected between the neutral direct current pole and a second connection point, a fourth controllable semiconductor switch connected between the second connection point and a negative direct current pole, resistance means connected between the first connection point and the second connection point, and control means configured to control the second controllable semiconductor switch and the third controllable semiconductor switch into a conducting state in response to detecting a fault in the resistance means.

Abstract: An arrangement for cooling a closed, sealed cabinet (1), comprising a thermosiphon heat exchanger (2) disposed inside the cabinet (1) and having an evaporator (3) and a condenser (4) for circulating a working fluid between the evaporator (3) and the condenser (4) in a closed loop, wherein the working fluid evaporated in the evaporator (3) by heat flows to the condenser (4) for cooling and the condensed working fluid flows back to the evaporator (3). The evaporator (3) is exposed to hot air flow generated inside the cabinet (1), and a heat transfer element (5) is attached to the condenser (3) in a sealed manner through a cabinet wall (6) for transferring heat to the outside of the cabinet (1).

Abstract: A method for monitoring a change in a capacitance in an electric system, and an electric system comprising a multilevel inverter and at least two capacitances connected in series between a negative DC pole and a positive DC pole of the inverter, wherein the connection point between the capacitances is connected to one of the at least one middle DC pole of the inverter, and a controller configured to provide by the inverter an AC current component to one of the at least one middle DC pole of the inverter, which AC current component is distributed between the two capacitances connected to the middle DC pole, and monitor resulting AC voltage components in the two capacitances, and determine on the basis of a difference between the monitored AC voltage components a change in at least one of the two capacitances.

Abstract: A three-level converter and a method for controlling a three-level converter, wherein the third (S31, S32, S33), the fourth (S41, S42, S43) and the fifth (S51, S52, S53) controllable semiconductor switch of a switching branch having, out of all the switching branches, the most positive voltage in its alternating current pole (AC1, AC2, AC3) is controlled to be non-conductive for the whole period of time when the switching branch in question has the most positive voltage in its alternating current pole, and the first (S11, S12, S13), the second (S21, S22, S23) and the sixth (S61, S62, S63) controllable semiconductor switch of a switching branch having, out of all the switching branches, the most negative voltage in its alternating current pole is controlled to be non-conductive for the whole period of time when the switching branch in question has the most negative voltage in its alternating current pole.

Abstract: The present disclosure describes a modulation method for controlling at least two parallel-connected, multi-phase power converters. The method comprises generating synchronized switching sequences for the power converters on the basis of a common modulation reference, wherein each synchronized switching sequence comprises a first half sequence followed by a second half sequence, and wherein, for at least one of the power converters, the first half sequence is a rising-edge half sequence rising-edge half sequence and the second half sequence is a falling-edge half sequence, and, for at least one other of the power converters, the first half sequence is a falling-edge half sequence and the second half sequence is a rising-edge half sequence.

Abstract: An arrangement for cooling a closed, sealed cabinet (1), comprising a thermosiphon heat exchanger (2) disposed inside the cabinet (1) and having an evaporator (3) and a condenser (4) for circulating a working fluid between the evaporator (3) and the condenser (4) in a closed loop, wherein the working fluid evaporated in the evaporator (3) by heat flows to the condenser (4) for cooling and the condensed working fluid flows back to the evaporator (3). The evaporator (3) is exposed to hot air flow generated inside the cabinet (1), and a heat transfer element (5) is attached to the condenser (3) in a sealed manner through a cabinet wall (6) for transferring heat to the outside of the cabinet (1).

Abstract: A switching branch for a three-level inverter, comprising a first and second switch (S1, S2) in series between a positive DC pole (P) and an AC pole (AC), a first and second diode (D1, D2) parallel to the first and second switches, a third and fourth switch (S3, S4) in series between a negative DC pole (N) and the AC pole, a third and fourth diode (D3, D4) parallel to the third and fourth switches, a fifth diode (D5) between a neutral DC pole (M) and a point between the first and second switches, a sixth diode (D6) between the neutral DC pole and a point between the third and fourth switches, a fifth switch (S5) and a seventh diode (D7) in series between the neutral DC and AC poles, and a sixth switch (S6) and an eighth diode (D8) in series between the neutral DC and AC poles.

Abstract: The present disclosure discloses a method and an apparatus implementing the method for minimizing a circulating current of parallel-connected inverters. The method can include, for at least one parallel-connected inverter, measuring a common-mode voltage of the inverter, and controlling a cycle length of the switching cycle on the basis of the common-mode voltage.

Abstract: A three-level converter and a method for controlling a three-level converter, wherein the third (S31, S32, S33), the fourth (S41, S42, S43) and the fifth (S51, S52, S53) controllable semiconductor switch of a switching branch having, out of all the switching branches, the most positive voltage in its alternating current pole (AC1, AC2, AC3) is controlled to be non-conductive for the whole period of time when the switching branch in question has the most positive voltage in its alternating current pole, and the first (S11, S12, S13), the second (S21, S22, S23) and the sixth (S61, S62, S63) controllable semiconductor switch of a switching branch having, out of all the switching branches, the most negative voltage in its alternating current pole is controlled to be non-conductive for the whole period of time when the switching branch in question has the most negative voltage in its alternating current pole. (FIG.

Abstract: Exemplary embodiments are directed to a method for controlling a switching branch of a three-level converter to enter a stop state. The switching branch including a first semiconductor switch and a second semiconductor switch, a first diode and a second diode, a third semiconductor switch and a fourth semiconductor switch, a third diode, and a fourth diode, a fifth semiconductor switch and a sixth semiconductor switch, a fifth diode, and a sixth diode, and a manner of controlling the semiconductor switches. When the switching branch is set to enter a stop state, current flowing in a main circuit of the switching branch is transferred in a controlled manner to diodes that conduct the current, when all the semiconductor switches of the main circuit of the converter are turned OFF.

Abstract: A switching branch for a three-level inverter, comprising a first and second switch (S1, S2) in series between a positive DC pole (P) and an AC pole (AC), a first and second diode (D1, D2) parallel to the first and second switches, a third and fourth switch (S3, S4) in series between a negative DC pole (N) and the AC pole, a third and fourth diode (D3, D4) parallel to the third and fourth switches, a fifth diode (D5) between a neutral DC pole (M) and a point between the first and second switches, a sixth diode (D6) between the neutral DC pole and a point between the third and fourth switches, a fifth switch (S5) and a seventh diode (D7) in series between the neutral DC and AC poles, and a sixth switch (S6) and an eighth diode (D8) in series between the neutral DC and AC poles.

Abstract: A method and an arrangement of producing a safe torque off procedure of an electrical drive including a control unit and one or more power units having controllable semiconductor switches. The method includes detecting a signal in a control unit indicating a requirement to stop the drive, generating, based on the detected signal, at least one safety-approved signal which when received in a power unit initiates shutting-down of the power unit, feeding the generated at least one safety-approved signal to one or more power units, and initiating the shutting down of the one or more power units upon the receipt of the at least one safety-approved signal, the at least one safety-approved signal initiating at least two different shut-down procedures of the one or more power units at different time instants.

Abstract: Exemplary embodiments for controlling a switching branch for a three-level converter, and a switching branch are disclosed. A first semiconductor switch and a second semiconductor switch, a first diode and a second diode, a third semiconductor switch and a fourth semiconductor switch, a third diode, and a fourth diode, a fifth semiconductor switch and a sixth semiconductor switch, a fifth diode, and a sixth diode, and a control arrangement for controlling the semiconductor switches are provided. The first semiconductor switch, the first diode, the fifth semiconductor switch and the fifth diode reside in a first switching branch-specific semiconductor module, and the fourth semiconductor switch, the fourth diode, the sixth semiconductor switch and the sixth diode reside in a second switching branch-specific semiconductor module.