Abstract: A first bridge circuit includes a first leg and a second leg. The first leg includes an upper arm and a lower arm. The upper arm includes a plurality of switching devices connected in series, a plurality of freewheeling diodes connected in antiparallel with the switching devices, respectively, and a plurality of snubber capacitors connected in parallel with the switching devices, respectively. A control circuit controls the first and second bridge circuits such that a dead time period is provided between a turn-on period of an upper arm and a turn-on period of a lower arm included in each of the first and second legs, in each of the first and second bridge circuits.

Abstract: Each DC/DC converter includes a transformer, first and second switching circuits each formed of a plurality of legs having a plurality of semiconductor switching elements, and capacitors. When detecting a malfunction in semiconductor switching elements, a control circuit halts a normal operation mode and controls the first switching circuit by a protection mode for turning OFF all the semiconductor switching elements, and controls the second switching circuit by a bypass mode for bypassing the capacitor by turning ON the semiconductor switching elements in a discharge leg and causing a short circuit between the secondary side terminals, after controlling the second switching circuit by a discharge mode for discharging the capacitor by turning ON the semiconductor switching element in a discharge leg.

Abstract: Each DC/DC converter includes a transformer, first and second switching circuits each formed of a plurality of legs having a plurality of semiconductor switching elements, capacitors, a discharge circuit connected in parallel to the secondary side capacitor, and a bypass switch for bypassing the capacitor. When detecting a malfunction in semiconductor switching elements, a control circuit turns OFF all of the semiconductor switching elements, and controls the bypass switch after discharge of the capacitor through the discharge circuit, so that the capacitor is bypassed.

Abstract: A first bridge circuit includes a first leg and a second leg. The first leg includes an upper arm and a lower arm. The upper arm includes a plurality of switching devices connected in series, a plurality of freewheeling diodes connected in antiparallel with the switching devices, respectively, and a plurality of snubber capacitors connected in parallel with the switching devices, respectively. A control circuit controls the first and second bridge circuits such that a dead time period is provided between a turn-on period of an upper arm and a turn-on period of a lower arm included in each of the first and second legs, in each of the first and second bridge circuits.

Abstract: Each DC/DC converter includes a transformer, first and second switching circuits each formed of a plurality of legs having a plurality of semiconductor switching elements, capacitors, a discharge circuit connected in parallel to the secondary side capacitor, and a bypass switch for bypassing the capacitor. When detecting a malfunction in semiconductor switching elements, a control circuit turns OFF all of the semiconductor switching elements, and controls the bypass switch after discharge of the capacitor through the discharge circuit, so that the capacitor is bypassed.

Abstract: A power conversion device includes M number of DC/DC converters, first-side terminals of the DC/DC converters are connected so that common current flows between both positive and negative terminals of first DC terminals of the power conversion device, and second-side terminals thereof are connected so that common current flows between both positive and negative terminals of second DC terminals of the power conversion device. The power conversion device further includes M-1 number of auxiliary converters each connected between two DC/DC converters and performing DC/DC conversion. The DC/DC converters control voltages of the second-side terminals and input voltage of the power conversion device. Each auxiliary converter controls voltages of the first-side terminals of the two DC/DC converters so as to be equalized.

Abstract: In a control device of a power conversion device, an AC control portion generates a first voltage command value representing an AC voltage component to be output from a plurality of chopper cells of each leg circuit. A DC control portion generates a second voltage command value representing a DC voltage component to be output from the plurality of chopper cells of each leg circuit. A circulating current control portion generates a third voltage command value to be output from the plurality of chopper cells of each leg circuit in order to suppress a circulating current. The circulating current control portion performs a non-linear operation with the first, second, and third voltage command values. The plurality of chopper cells of each leg circuit operate in accordance with a result of the non-linear operation.

Abstract: A power conversion device includes a plurality of leg circuits and a control device. The plurality of leg circuits correspond to respective phases of an AC circuit and connected in parallel between common first and second DC terminals. Each leg circuit includes a plurality of chopper cells each including an energy storage and cascaded to one another and at least one inductance connected in series to the plurality of chopper cells. The control device controls an operation of only at least one chopper cell included in each leg circuit based on a circulating current which circulates through the leg circuits.

Abstract: Each of a plurality of specified chopper cells which are some of a plurality of chopper cells included in each leg circuit in a power conversion device is configured as a full bridge. A control device controls operations of first and second switching elements of each specified chopper cell based on a circulating current which circulates through each leg circuit. The control device controls operations of third and fourth switching elements of each specified chopper cell based on a voltage of a capacitor of the specified chopper cell.

Abstract: A power conversion device in which a plurality of converter cells are connected in series with one another. The converter cells each include two or more semiconductor devices, an energy storage element and a bypass element including a constituent element for setting the bypass element to be close-circuited by detecting abnormality of a converter cell, and including a constituent element for controlling, among the semiconductor devices, a semiconductor device connected in parallel with the bypass element to set in a turn-on state, at the same time when the bypass element is set close-circuited or in advance of its close circuit.

Abstract: In an electric power conversion device which performs power conversion between multiphase AC and DC, a first converter cell of a first arm for each phase of a power converter includes: a capacitor; a Leg A having upper and lower arms having switching elements; and a Leg B having upper and lower arms one of which has a switching element and the other of which has only a diode, and a second converter cell of a second arm includes: a capacitor; and a Leg Aa having upper and lower arms having switching elements. A control device has a steady mode and a protection mode. When short-circuit between DC terminals of the power converter is detected, the control device switches from the steady mode to the protection mode, turns off all the switching elements of the first converter cell of the first arm, and controls the second converter cell of the second arm so as to perform reactive power compensation operation.

Abstract: An electric power conversion device includes a first arm and a second arm each including converter cells. The converter cell of the first arm is a first converter cell having a full-bridge configuration including an energy storing element and semiconductor switching elements. The converter cell of the second arm is a second converter cell having a half-bridge configuration including an energy storing element and semiconductor switching elements. Thus, short-circuit current between DC terminals is suppressed.

Abstract: When switching operations of converter cells are stopped due to temporary voltage reduction in an AC system, a voltage determination unit performs determination regarding a voltage of each DC capacitor after a predetermined period has passed, and a charge control unit transmits a charging gate signal, via a gate control unit, to select a converter cell at a voltage level at which a self-feeding circuit of the converter cell is operable. Thus, a DC capacitor of a converter cell whose voltage is lower than the voltage level at which a self-feeding circuit is operable is charged, thereby enabling switching operations of all the converter cells.

Abstract: In a control device of a power conversion device, an AC control portion generates a first voltage command value representing an AC voltage component to be output from a plurality of chopper cells of each leg circuit. A DC control portion generates a second voltage command value representing a DC voltage component to be output from the plurality of chopper cells of each leg circuit. A circulating current control portion generates a third voltage command value to be output from the plurality of chopper cells of each leg circuit in order to suppress a circulating current. The circulating current control portion performs a non-linear operation with the first, second, and third voltage command values. The plurality of chopper cells of each leg circuit operate in accordance with a result of the non-linear operation.

Abstract: Using two converters placed in a primary-side and a secondary-side and each configured as a single-phase full-bridge, and one single-phase transformer TR, a power conversion device converts DC power of a primary-side capacitor to which a primary-side DC voltage is applied, to DC power of a secondary-side capacitor to which a secondary-side DC voltage is applied, through a transformer. A control device sets a dead time Td1 for the converter serving as a power-transferring side converter, to be equal to or less than a current-polarity reversal time Tcmtt, to thereby surely achieve zero-voltage switching.

Abstract: An electric power conversion device includes a first arm and a second arm each including converter cells. The converter cell of the first arm is a first converter cell having a full-bridge configuration including an energy storing element and semiconductor switching elements. The converter cell of the second arm is a second converter cell having a half-bridge configuration including an energy storing element and semiconductor switching elements. Thus, short-circuit current between DC terminals is suppressed.

Abstract: In an electric power conversion device which performs power conversion between multiphase AC and DC, a first converter cell of a first arm for each phase of a power converter includes: a capacitor; a Leg A having upper and lower arms having switching elements; and a Leg B having upper and lower arms one of which has a switching element and the other of which has only a diode, and a second converter cell of a second arm includes: a capacitor; and a Leg Aa having upper and lower arms having switching elements. A control device has a steady mode and a protection mode. When short-circuit between DC terminals of the power converter is detected, the control device switches from the steady mode to the protection mode, turns off all the switching elements of the first converter cell of the first arm, and controls the second converter cell of the second arm so as to perform reactive power compensation operation.

Abstract: When switching operations of converter cells are stopped due to temporary voltage reduction in an AC system, a voltage determination unit performs determination regarding a voltage of each DC capacitor after a predetermined period has passed, and a charge control unit transmits a charging gate signal, via a gate control unit, to select a converter cell at a voltage level at which a self-feeding circuit of the converter cell is operable. Thus, a DC capacitor of a converter cell whose voltage is lower than the voltage level at which a self-feeding circuit is operable is charged, thereby enabling switching operations of all the converter cells.

Abstract: Using two converters placed in a primary-side and a secondary-side and each configured as a single-phase full-bridge, and one single-phase transformer TR, a power conversion device converts DC power of a primary-side capacitor to which a primary-side DC voltage is applied, to DC power of a secondary-side capacitor to which a secondary-side DC voltage is applied, through a transformer. A control device sets a dead time Td1 for the converter serving as a power-transferring side converter, to be equal to or less than a current-polarity reversal time Tcmtt, to thereby surely achieve zero-voltage switching.

Abstract: A power conversion device including: an energy storage unit which receives and stores voltage of a self-power-feeding device; and a bypass unit drive device which, when voltage of the self-power-feeding device becomes smaller than a predetermined lower limit value, causes a bypass unit to perform short-circuiting operation by power stored in the energy storage unit. Thus, by appropriately setting the above voltage lower limit value as a threshold value for the short-circuiting operation, it becomes possible to swiftly and reliably perform short-circuiting protection operation even if a cell converter has failed, thus it is possible to always safely continue the operation of the power conversion device.