Abstract: The present disclosure is directed at an AC drive for driving an electric motor. The AC drive has a 3-phase diode bridge, an inverter and a snubber board with multilayer printed circuit board elements, wherein the power lane in every layer of every element is connected to only one potential DC- or DC+, each element includes two capacitors of inverted polarity, wherein each element includes two C-shaped bus bars and wherein the C-shaped bus bars of two neighbouring elements are placed in close proximity to each other.

Abstract: The invention is directed at an electric power converter, such as an electric motor drive for driving an electric motor. The converter includes a cooling system with a heat sink for dissipating thermal energy generated by the converter and with coolant flow means for cooling the heat sink, first measuring means for measuring the coolant inlet temperature, second measuring means for measuring the heat sink temperature, estimating means for estimating the thermal energy transferred to the heat sink, wherein the converter is provided for estimating the thermal resistance of the heat sink based on the measured temperatures and the estimated thermal energy transferred to the heat sink, for comparing the estimated thermal resistance to reference values and for outputting a signal, if the difference between the estimated thermal resistance and the reference values exceeds a threshold value. The invention is also directed at a method for operating the electric power converter.

Abstract: A controller (203) comprises a processing system (205) for controlling a power electronic converter during a short circuit taking place in a direct voltage side of the power electronic converter. The processing system recognizes a direction of current in a phase (126-128) of an alternating voltage side of the power electronic converter, sets a high-leg controllable switch (108-110) of the phase to a conductive state while keeping a low-leg controllable switch (111-113) of the phase in a non-conductive state when the recognized direction of the current is outwards from the power electronic converter, and otherwise sets the low-leg controllable switch to the conductive state while keeping the high-leg controllable switch in the non-conductive state. Thermal loadings of freewheeling diodes (114-119) of the power electronic converter are reduced since currents needed to burn input fuses (122) of the power electronic converter are shared between the controllable switches and the freewheeling diodes.

Abstract: An electronic circuit includes: a first series-connection of DC link capacitors (CA1, . . . , CAm) and a second series-connection of DC link capacitors (CB1, . . . , CBn) connected in parallel between DC bus bars (DC+, DC?), wherein the first series has a first node (A) between the DC link capacitors thereof and the second series has a second node (B) between the DC link capacitors thereof; and a short-circuit module (301; 401, 407) configured to receive a voltage difference (UM) between the first node and the second node and to cause the DC bus bars short circuited in response to the received voltage difference being greater than a predetermined threshold.

Abstract: A controller (203) comprises a processing system (205) for controlling a power electronic converter during a short circuit taking place in a direct voltage side of the power electronic converter. The processing system recognizes a direction of current in a phase (126-128) of an alternating voltage side of the power electronic converter, sets a high-leg controllable switch (108-110) of the phase to a conductive state while keeping a low-leg controllable switch (111-113) of the phase in a non-conductive state when the recognized direction of the current is outwards from the power electronic converter, and otherwise sets the low-leg controllable switch to the conductive state while keeping the high-leg controllable switch in the non-conductive state. Thermal loadings of freewheeling diodes (114-119) of the power electronic converter are reduced since currents needed to burn input fuses (122) of the power electronic converter are shared between the controllable switches and the freewheeling diodes.

Abstract: An electronic circuit includes: a first series-connection of DC link capacitors (CA1, . . . , CAm) and a second series-connection of DC link capacitors (CB1, . . . , CBn) connected in parallel between DC bus bars (DC+, DC?), wherein the first series has a first node (A) between the DC link capacitors thereof and the second series has a second node (B) between the DC link capacitors thereof; and a short-circuit module (301; 401, 407) configured to receive a voltage difference (UM) between the first node and the second node and to cause the DC bus bars short circuited in response to the received voltage difference being greater than a predetermined threshold.