US-12620830-B2 - Backfeed protection circuit

US12620830B2US 12620830 B2US12620830 B2US 12620830B2US-12620830-B2

Abstract

Examples of the disclosure include a power system including an input power connection, a return connection, a power converter having a converter input, a backfeed switch coupled between the input power connection and the converter input, at least one safety switch coupled between the converter input and the return connection, and at least one control circuit configured to control the at least one safety switch to be closed when the backfeed switch opens.

Inventors

Jonas Sonsby Mouridsen

Assignees

SCHNEIDER ELECTRIC IT CORPORATION

Dates

Publication Date: 20260505
Application Date: 20221229

Claims (20)

1 . A power system comprising: an input power connection; a return connection; a power converter having a converter input; a backfeed switch coupled between the input power connection and the converter input; at least one safety switch coupled between the converter input and the return connection; and at least one control circuit configured to: control opening of the backfeed switch to disconnect the converter input from the input power connection; and control closing of the at least one safety switch to connect the converter input to the return connection, wherein connecting the converter input to the return connection maintains the converter input at a neutral voltage responsive to opening the backfeed switch.
2 . The power system of claim 1 , wherein the at least one safety switch includes a relay having a first connection coupled between the converter input and the backfeed switch, and a second connection coupled to the return connection.
3 . The power system of claim 1 , wherein the at least one safety switch includes at least one power-factor-correction (PFC) boost switch.
4 . The power system of claim 3 , wherein the PFC boost switch is configured to provide power-factor correction to input power received at the input power connection.
5 . The power system of claim 1 , wherein closing the at least one safety switch couples the converter input to a voltage of the return connection while the backfeed switch is open, and wherein the voltage of the return connection is the neutral voltage.
6 . The power system of claim 1 , further comprising: an inverter coupled to the power converter; an output connection; and at least one inverter switch coupled between the inverter and the output connection.
7 . The power system of claim 6 , wherein the at least one control circuit is further configured to: determine, while the at least one safety switch is closed, a voltage at the converter input; and open the at least one inverter switch responsive to determining that the voltage exceeds a voltage threshold.
8 . The power system of claim 6 , further comprising: a second input power connection; and a bypass switch having a first connection coupled to the second input power connection and a second connection coupled between the at least one inverter switch and the output connection.
9 . The power system of claim 1 , wherein the at least one safety switch is configured to open when the backfeed switch closes.
10 . The power system of claim 1 , wherein the at least one control circuit is further configured to: determine, while the at least one safety switch is closed, a voltage at the converter input; and shut down the power system responsive to determining that the voltage exceeds a voltage threshold.
11 . The power system of claim 1 , wherein the backfeed switch includes at least one backfeed relay.
12 . A method of operating a power system having an input power connection, a return connection, a power converter having a converter input, a backfeed switch coupled between the input power connection and the converter input, and at least one safety switch coupled between the converter input and the return connection, the method comprising: opening the backfeed switch to disconnect the converter input from the input power connection; and closing the at least one safety switch to connect the converter input to the return connection, wherein connecting the converter input to the return connection maintains the converter input at a neutral voltage responsive to opening the backfeed switch.
13 . The method of claim 12 , wherein the at least one safety switch includes at least one power-factor-correction (PFC) boost switch, and wherein the method further comprises providing, by the PFC boost switch, power-factor correction to input power received at the input power connection.
14 . The method of claim 13 , wherein closing the at least one safety switch couples the converter input to a voltage of the return connection while the backfeed switch is open, and wherein the voltage of the return connection is the neutral voltage.
15 . The method of claim 12 , wherein the power system includes an inverter coupled to the power converter, an output connection, and at least one inverter switch coupled between the inverter and the output connection, the method further comprising: determining, while the at least one safety switch is closed, a voltage at the converter input; and opening the at least one inverter switch responsive to determining that the voltage exceeds a voltage threshold.
16 . The method of claim 12 , further comprising opening the at least one safety switch when the backfeed switch closes.
17 . The method of claim 12 , further comprising: determining, while the at least one safety switch is closed, a voltage at the converter input; and shutting down the power system responsive to determining that the voltage exceeds a voltage threshold.
18 . A non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power system having an input power connection, a return connection, a power converter having a converter input, a backfeed switch coupled between the input power connection and the converter input, and at least one safety switch coupled between the converter input and the return connection, the sequences of computer-executable instructions including instructions that instruct at least one processor to: open the backfeed switch to disconnect the converter input from the input power connection; and close the at least one safety switch to connect the converter input to the return connection, wherein connecting the converter input to the return connection maintains the converter input at a neutral voltage responsive to opening the backfeed switch.
19 . The non-transitory computer-readable medium of claim 18 , wherein the power system includes an inverter coupled to the power converter, an output connection, and at least one inverter switch coupled between the inverter and the output connection, and wherein the instructions further instruct the at least one processor to: determine, while the at least one safety switch is closed, a voltage at the converter input; and open the at least one inverter switch responsive to determining that the voltage exceeds a voltage threshold.
20 . The non-transitory computer-readable medium of claim 18 , wherein the instructions further instruct the at least one processor to: determine, while the at least one safety switch is closed, a voltage at the converter input; and shut down the power system responsive to determining that the voltage exceeds a voltage threshold.

Description

BACKGROUND 1. Field of the Disclosure At least one example in accordance with the present disclosure relates generally to backfeed protection. 2. Discussion of Related Art Power devices, such as uninterruptible power supplies (UPSs), may be used to provide regulated, uninterrupted power for sensitive and/or critical loads, such as computer systems and other data-processing systems. Existing UPSs include online UPSs, offline UPSs, line-interactive UPSs, as well as others. UPSs may provide output power to a load. The output power may be derived from a primary source of power, such as a utility-mains source, and/or derived from a back-up source of power, such as an energy-storage device. SUMMARY According to at least one aspect of the present disclosure, a power system is provided comprising an input power connection, a return connection, a power converter having a converter input, a backfeed switch coupled between the input power connection and the converter input, at least one safety switch coupled between the converter input and the return connection, and at least one control circuit configured to control the at least one safety switch to be closed when the backfeed switch opens. In various examples, the at least one safety switch includes a relay having a first connection coupled between the converter input and the backfeed switch, and a second connection coupled to the return connection. In some examples, the at least one safety switch includes at least one power-factor-correction (PFC) boost switch. In one example, the PFC boost switch is configured to provide power-factor correction to input power received at the input power connection. In various examples, closing the at least one safety switch couples the converter input to neutral. In some examples, the power system includes an inverter coupled to the power converter, an output connection, and at least one inverter switch coupled between the inverter and the output connection. In one example, the at least one control circuit is further configured to determine, while the at least one safety switch is closed, a voltage at the converter input, and open the at least one inverter switch responsive to determining that the voltage exceeds a voltage threshold. In various examples, the power system includes a second input power connection, and a bypass switch having a first connection coupled to the second input power connection and a second connection coupled between the at least one inverter switch and the output connection. In some examples, the at least one safety switch is configured to open when the backfeed switch closes. In one example, the at least one control circuit is further configured to determine, while the at least one safety switch is closed, a voltage at the converter input, and shut down the power system responsive to determining that the voltage exceeds a voltage threshold. In various examples, the backfeed switch includes at least one backfeed relay. According to at least one aspect of the disclosure, a method of operating a power system having an input power connection, a return connection, a power converter having a converter input, a backfeed switch coupled between the input power connection and the converter input, and at least one safety switch coupled between the converter input and the return connection is provided, the method comprising, opening the backfeed switch to disconnect the converter input from the input power connection, and closing the at least one safety switch responsive to opening the backfeed switch to connect the converter input to the return connection. In various examples, the at least one safety switch includes at least one power-factor-correction (PFC) boost switch and the method further comprises providing, by the PFC boost switch, power-factor correction to input power received at the input power connection. In some examples, closing the at least one safety switch couples the converter input to neutral. In one example, the power system includes an inverter coupled to the power converter, an output connection, and at least one inverter switch coupled between the inverter and the output connection, and the method includes determining, while the at least one safety switch is closed, a voltage at the converter input, and opening the at least one inverter switch responsive to determining that the voltage exceeds a voltage threshold. In various examples, the method includes opening the at least one safety switch when the backfeed switch closes. In some examples, the method includes determining, while the at least one safety switch is closed, a voltage at the converter input, and shutting down the power system responsive to determining that the voltage exceeds a voltage threshold. According to at least one aspect of the disclosure, a non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power system having an input power connection, a return connection,