Disclosed is a DC-DC converter of a power conversion system. comprising first to fourth switches; fifth to eighth switches; a first capacitor connected to the first and second switches; a second capacitor connected to the fifth and sixth switches; a third capacitor connected to the third and fourth switches; a fourth capacitor connected to the seventh and eighth switches; a first inductor connected to a first node between the first and second switches, and a second node between the fifth and sixth switches; and a second inductor connected to a third node between the third and fourth switches, and a fourth node between the seventh and eighth switches, wherein the first and second inductors are coupled inductors, and a fifth node between the second and third switches, and a sixth node between the sixth and seventh switches are electrically equivalent.

An electrical power distribution system includes a first high side sub-module including a high side converter and a high side energy storage device. The first high side sub-module is electrically coupled to a high side load that requires a high voltage or medium voltage DC, the high voltage DC being higher than the medium voltage DC. The system also includes a first low side sub-module including a low side converter and a low side energy storage device. The first high side sub-module and the first low side sub-module are configured to be inductively coupled. The first high side sub-module and the first low side sub-module form a first module.

Disclosed is an optimized energy interconnection system for an urban railway train in the technical field of urban railway transportation power supply, for addressing the technical problem that distribution of regenerative braking energy flows cannot be accurately determined. The system includes a DC intermediate bus and a multi-port flow controllable energy router. The multi-port flow controllable energy router can comprehensively control a source and a load connected in parallel on the DC intermediate bus and thus can accurately determine the distribution of regenerative braking energy flows, thereby forming a well-developed system for evaluating usage of the braking energy.

Aspects of the invention overcome a monolithic approach to conventional low-frequency LPTs by using a high-frequency solid-state alternating current ac/ac modular power-conversion approach. Embodiments of the invention enable the ability to incorporate new technologies without in all cases redoing a LPT design from scratch. Furthermore, given that LPTs are for the long term, aspects of the invention ensure that they are durable, efficient, and fault tolerant with overloading capability.

A conversion device includes: an inductor electrically connected to the AC power grid; a first-stage converter configured to output a bus voltage according to the AC power grid, wherein the first-stage converter includes an N-level alternating current-direct current (AC-DC) converter, and the N-level AC-DC converter includes a plurality of switch bridge arms, wherein both an upper bridge arm and a lower bridge arm of each of the plurality of switch bridge arms of the N-level AC-DC converter include a plurality of semiconductor devices connected in series, and a rated withstand voltage Vsemi of each of the semiconductor devices is greater than or equal to (Vbus*δ)/((N−1)*Nseries*λ); and a second-stage converter configured to convert the bus voltage into an output voltage to supply energy to the load.

In one embodiment, an apparatus includes a surge voltage blocker circuit to couple between a distribution grid network and a grid-side power converter of a power conversion system. The surge voltage blocker circuit may include a plurality of series-coupled AC switch circuits, each including: a bidirectional switch formed of a first power transistor and a second power transistor; and a transient voltage suppression device coupled in parallel with the bidirectional switch.

Provided is a power conversion system that can suppress a fault in a short-circuiting switch that bypasses a fault unit and enhance the reliability and redundancy of the system. The power conversion system is provided with a plurality of power converter units that are formed by using semiconductor switch elements and are connected in series, and comprises: switch elements that are provided to input terminals and/or output terminals of the power converter units and bypass the power converter units; and overvoltage suppressing elements which are connected in parallel with the switch elements and in which conducting states are changed by an application of a prescribed voltage.

A power converter circuit is disclosed. In one aspect, the power converter circuit includes a first top buck converter circuit coupled in parallel to a second top buck converter circuit at a first connection node and at a second connection node, and a bottom buck converter circuit coupled in series to each of the first and second top buck converter circuits at the second connection node, a power input terminal coupled to the first and second top buck converter circuits, and a power output terminal coupled to the bottom buck converter circuit and to the first connection node.

A power module includes N inverter units outputting N AC voltages and being coupled to N high-frequency AC terminals, wherein the N high-frequency AC terminals are cascaded and connected to a post-stage rectifier circuit. A phase-shift control method for the power module includes: setting at least two phase-shift sequences, wherein phase sequence numbers of the N AC voltages of the N inverter units are different in the at least two phase-shift sequences; in one switching period, controlling the N AC voltages of the N inverter units to shift a first angle according to a first phase-shift sequence of the at least two phase-shift sequences; and in another switching period, controlling the N AC voltages of the N inverter units to shift the first angle according to a second phase-shift sequence of the at least two phase-shift sequences.

A method for controlling a power module includes: configuring N cells in cascade connection, where N is a positive integer equal to or greater than 2, each cell comprising a bidirectional switching unit and a non-controlled rectifier bridge, the bidirectional switching unit being connected to central points of two bridge arms of the non-controlled rectifier bridge; controlling each cell to operate in one of three operating modes of a modulation mode, a bypass mode and a non-controlled rectifying mode, wherein in the N cells, m1 cells operate in the bypass mode, where 0≤m1≤M1, m2 cells operate in the non-controlled rectifying mode, where 0≤m2≤M2, m3 cells operate in the modulation mode and can realize power factor correction, where 0<m3; wherein m1+m2+m3=N, M1 is the allowable number of cells for bypass in the system, and M2 is the allowable number of cells for non-controlled rectification in the system.