EP-4735296-A1 - CONTROL OF INNER POWER FLOWS OF AN ELECTRICAL SYSTEM

EP4735296A1EP 4735296 A1EP4735296 A1EP 4735296A1EP-4735296-A1

Abstract

The present disclosure relates to a method for controlling inner power flows of an AC electrical system comprising an AC power source, an electrical component, and a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the AC power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, wherein each of the plurality of cells comprises an AC- to-DC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells or an AC-to-AC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells, the method comprising: obtaining at least one electrical parameter of the AC electrical system; generating a control signal for each of the plurality of cells based on the obtained at least one electrical parameter; and controlling the inner power flows of the AC electrical system by adjusting voltages of the primary side of the plurality of cells based on the generated control signal, such that a voltage difference between a voltage of the AC power source and a sum of the voltages of the primary side of the plurality of cells causes a controlled current flow through the electrical component, wherein adjusting the voltages of the primary side of the plurality of cells comprises adjusting a magnitude and a phase of the voltages of the primary side of the plurality of cells by controlling the first AC portion of the AC-to-DC converter based on the generated control signal or by controlling the first AC portion of the AC-to-AC converter based on the generated control signal, and wherein a sum of the magnitudes of the voltages of the primary side of the plurality of cells is greater than a magnitude value of the voltage of the AC power source.

Inventors

MOGOROVIC, Marko
SIEMASZKO, Daniel
YUAN, Chunming

Assignees

Hitachi Energy Ltd

Dates

Publication Date: 20260506
Application Date: 20240913

Claims (12)

1. A method for controlling inner power flows of an AC electrical system comprising an AC power source, an electrical component, and a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the AC power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, wherein each of the plurality of cells comprises an AC-to-DC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells or an AC-to-AC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells, the method comprising: obtaining at least one electrical parameter of the AC electrical system; generating a control signal for each of the plurality of cells based on the obtained at least one electrical parameter; and controlling the inner power flows of the AC electrical system by adjusting voltages of the primary side of the plurality of cells based on the generated control signal, such that a voltage difference between a voltage of the AC power source and a sum of the voltages of the primary side of the plurality of cells causes a controlled current flow through the electrical component, wherein adjusting the voltages of the primary side of the plurality of cells comprises adjusting a magnitude and a phase of the voltages of the primary side of the plurality of cells by controlling the first AC portion of the AC-to-DC converter based on the generated control signal or by controlling the first AC portion of the AC-to-AC converter based on the generated control signal, and wherein a sum of the magnitudes of the voltages of the primary side of the plurality of cells is greater than a magnitude value of the voltage of the AC power source.
2. The method of claim 1, wherein the sum of the magnitudes of the voltages of the primary side of the plurality of cells is greater than the magnitude value of the voltage of the AC power source by at least 10 percent, preferably 25 percent, of the magnitude value of the voltage of the AC power source, and/or the sum of the magnitudes of the voltages of the primary side of the plurality of cells is greater than the magnitude value of the voltage of the AC power source by at most 33 percent, preferably 30 percent, and more preferably 25 percent, of the magnitude value of the voltage of the AC power source.
3. The method of claim 1 or 2, wherein the plurality of cells comprises a secondary side, different from the primary side of the plurality of cells, and wherein the plurality of cells are galvanically isolated from one another at the secondary side of the plurality of cells.
4. The method of any one of claims 1 to 3, wherein a voltage of the power grid, the voltages of the primary side of the plurality of cells, the controlled current, and the voltage drop over the electrical component are vectors comprising a magnitude and phase information, and the sum of the voltages of the primary side of the plurality of cells is a vector sum.
5. The method of any one of claims 1 to 4, wherein the AC electrical system further comprises a first switch and a second switch, the first switch electrically couples the power grid to the electrical component in series, the second switch being electrically coupled to a node between the first switch and the electrical component, and the second switch electrically couples the power grid to the electrical component in parallel.
6. The method of claim 5, further comprising: closing one of the first switch and the second switch; and opening the other one of the first switch and the second switch.
7. The method of any one of claims 1 to 6, wherein the electrical component is resistive, or the electrical component is inductive and/or capacitive, and optionally resistive.
8. The method of any one of claims 1 to 7, wherein the obtained at least one electrical parameter is a voltage and/or a current of the AC power source, the electrical component, the primary side of the power converter, or the primary side of the plurality of cells.
9. The method of any one of claims 1 to 8, wherein the power of at least one of the plurality of cells flows bidirectionally based on the generated control signal.
10. A device for controlling inner power flows of an AC electrical system comprising an AC power source, an electrical component, and a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the AC power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, wherein each of the plurality of cells comprises an AC-to-DC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells or an AC-to-AC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells, wherein the device comprises a processor being configured to: obtain at least one electrical parameter of the AC electrical system; generate a control signal for each of the plurality of cells based on the obtained at least one electrical parameter; and control the inner power flows of the AC electrical system by adjusting voltages of the primary side of the plurality of cells based on the generated control signal, such that a voltage difference between a voltage of the AC power source and a sum of the voltages of the primary side of the plurality of cells causes a controlled current flow through the electrical component, wherein adjusting the voltages of the primary side of the plurality of cells comprises adjusting a magnitude and a phase of the voltages of the primary side of the plurality of cells by controlling the first AC portion of the AC-to-DC converter based on the generated control signal or by controlling the first AC portion of the AC-to-AC converter based on the generated control signal, and wherein a sum of the magnitudes of the voltages of the primary side of the plurality of cells is greater than a magnitude value of the voltage of the AC power source.
11. The device of claim 10, wherein the processor is further configured to perform the method according to any one of claims 2 to 9.
12. A system for controlling inner power flows of an AC electrical system, wherein the system comprises the device according to claim 10 or 11, and the AC electrical system comprising an AC power source, an electrical component, a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the AC power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, wherein each of the plurality of cells comprises an AC-to-DC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells or an AC-to-AC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells.

Description

CONTROL OF INNER POWER FLOWS OF AN ELECTRICAL SYSTEM The present disclosure relates to a method, device, and system for controlling inner power flows of an electrical system. As the technology evolves, electrical vehicles (EVs) are equipped with an increasing battery capacity and faster charging speed (e.g., DC fast charging power is also required to reach 350kW~600kW). Accordingly, the new EVs' voltage platform is shifting from 400V to 800V- lkV. This indicates that, in the upcoming years, different charging infrastructures are likely to be required with different battery voltage platforms and/or charging power levels. However, it is impractical to install different separate chargers to meet the changing requirements due to the limited available footprint, e.g., highway rest stops, service stations, and petrol stations. Thus, it is desirable to develop a modular and reconfigurable power converter that is capable of delivering power to the EVs at different voltage and power levels, preferably for different charging ports, but only within one power conversion. Such power converter may be referred to as a multiplexing power converter. Moreover, in an EV charging infrastructure (EVCI), it is further desirable to flexibly connect car batteries with bidirectional flow capability, together with other loads and sources. Such desirable modularity and reconfigurability of a power converter may be achieved by stacking multiple cells in a power converter. However, this does not sufficiently meet the aforementioned requirements without a proper control, in particular the power control of the active power flow in each of the stacked multiple cells that takes care of the voltage balance, that flexibly routes powers involved, and that responds fast to any new re-configuration requests from the situation of the EVs present. To this end, a solid-state transformer (SST) may be used owing to, among others, the controllability thereof. In particular, an AC/DC based (or DC/DC with one bulky AC/DC) modular cell comprising an SST may be used. On the AC side, it is often required to control both active and reactive powers which may come as a challenge when full flexibility is requested on the individual cells. Thus, there is a need to improve a method, device, and system for controlling inner power flows of an electrical system, in particular so as to enable a flexibility of following P,Qset points in various ways, while keeping the voltage balance on the individual output ports of the cells comprised in the power converter, and further while re-routing powers as requested by the EV batteries, which can be charged or discharged for a possible support when the situation requires it. The present disclosure relates to a method for controlling inner power flows of an electrical system comprising a power source, an electrical component, and a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, the method comprising: obtaining at least one electrical parameter of the electrical system; generating a control signal for each of the plurality of cells based on the obtained at least one electrical parameter; and controlling the inner power flows of the electrical system by adjusting voltages of the primary side of the plurality of cells based on the generated control signal, such that a voltage difference between a voltage of the power source and a sum of the voltages of the primary side of the plurality of cells causes a controlled current flow through the electrical component. The present disclosure relates to a method for controlling inner power flows of an AC electrical system comprising an AC power source, an electrical component, and a power converter having a primary side, wherein the primary side of the power converter is electrically coupled to the AC power source via the electrical component, wherein the power converter comprises a plurality of cells being electrically coupled in series to one another at a primary side of the plurality of cells, wherein each of the plurality of cells comprises an AC- to-DC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells or an AC-to-AC converter having a first AC portion being electrically coupled to the primary side of the plurality of cells, the method comprising: obtaining at least one electrical parameter of the AC electrical system; generating a control signal for each of the plurality of cells based on the obtained at least one electrical parameter; and controlling the inner power flows of the AC electrical system by adjusting voltages of the primary side of the plurality of cells based on the generated control signal, such that a voltage difference between a voltage of