US-20260128581-A1 - ELECTRICAL PROTECTION CIRCUIT FOR ENERGY STORAGE UNIT

US20260128581A1US 20260128581 A1US20260128581 A1US 20260128581A1US-20260128581-A1

Abstract

Embodiments herein provide an electrical protection circuit ( 100 ) for connecting an Energy Storage Unit, ESU ( 10 ) to a main power line ( 80 ). The electrical protection circuit ( 100 ) comprises first and second main terminals configured to be connected to a main power line, first and second ESU terminals connected to the ESU ( 10 ). The first main terminal is connected to the first ESU terminal via a first normally closed, NC, switch ( 20 ). The first main terminal is connected to the second main terminal via a normally open, NO switch ( 40 ). The first NC switch ( 20 ) is configured to be opened thereby to disconnect the ESU ( 10 ) from the main power line ( 80 ), and the NO switch ( 40 ) is configured to be closed thereby to bypass the ESU ( 10 ) from the main power line ( 80 ) in order to achieve electrical protection for the ESU ( 10 ).

Inventors

Panagiotis BAKAS
Anton SODERBLOM
Zichi Zhang
Haofeng Bai
Aleksandr Viatkin

Assignees

HITACHI ENERGY LTD

Dates

Publication Date: 20260507
Application Date: 20240322
Priority Date: 20230425

Claims (12)

1 . An electrical protection circuit for connecting an Energy Storage Unit (ESU) to a main power line, wherein the electrical protection circuit comprising: a first main terminal configured to be connected to the main power line; a second main terminal configured to be connected to the main power line, wherein the second main terminal is configured for a lower electric potential than the first main terminal; a first ESU terminal configured to be connected to a positive terminal of the ESU; a second ESU terminal configured to be connected to a negative terminal of the ESU; wherein the first main terminal is connected to the first ESU terminal via a first normally closed (NC) switch; and a first diode with an anode connected to the first main terminal, and a cathode connected to the first ESU terminal, wherein a parallel combination of the first NC switch and the first diode forms a closed path for a charging current and a discharging current flowing between the main power line and the ESU during operation, wherein a discharging circuit comprising a resistor in series with a discharging switch, wherein the discharging circuit is connected between the first ESU terminal and the second ESU terminal, wherein the discharging switch is another normally open (NO) switch; wherein the discharging switch is configured to be closed thereby to discharge the ESU through the resistor in order to achieve the electrical protection for the ESU; wherein the first main terminal is connected to the second main terminal via a normally NO switch and a second diode being connected in parallel with the NO switch with a cathode connected to the first main terminal, and an anode connected to the second main terminal; wherein the first NC switch is configured to be opened thereby to disconnect the ESU from the main power line, and the NO switch is configured to be closed thereby to bypass the ESU from the main power line in order to achieve electrical protection for the ESU; a second NC switch connected in series with the first NC switch; and a third NC switch connected in series with the ESU, wherein a combination of the second NC switch and the third NC switch is configured to disconnect the ESU and the discharging circuit from the main power line thereby achieving electrical protection for the ESU, wherein the second NC switch is configured to be opened to disconnect the ESU and the discharging circuit from the main power line; and the third NC switch is configured to be opened after opening of the second NC switch and discharging of the ESU through the resistor, thereby achieving electrical protection for the ESU.
2 . The electrical protection circuit according to claim 1 , wherein the third NC switch is configured to be opened after discharging of the ESU through the resistor; and the second NC switch is configured to be opened after opening of the third NC switch, thereby achieving electrical protection for the ESU.
3 . The electrical protection circuit according to claim 1 , further comprising: a resistor connected in parallel to the first NC switch, wherein the closing of the NO switch causes the ESU to discharge through the resistor thereby achieving electrical protection for the ESU.
4 . The electrical protection circuit according to claim 1 , wherein the first NC switch, the second NC switch, the third NC switch, the NO switch, and the discharging switch are of same or different types and connectable in series or parallel configuration.
5 . The electrical protection circuit according to claim 1 , wherein the ESU is at least one of a battery unit or a supercapacitor; and wherein the electrical protection circuit is configured to maintain uninterrupted current flow for rest of system other than the ESU during the bypassing.
6 . A method for connecting an Energy Storage Unit (ESU) to a main power line, the method comprising: opening a first normally closed (NC) switch to disconnect the ESU from the main power line, wherein a parallel combination of the first NC switch and a first diode forms a closed path for a charging current and a discharging current flowing between the main power line and the ESU during operation, wherein opening the first NC switch causes the charging current to flow from the main power line to the ESU through the first diode and wherein opening the first NC switch causes the discharging current to flow to the main power line through a second diode being connected in parallel with a normally open (NO) switch, thereby disconnecting the ESU; closing the NO switch to bypass current flowing through the ESU, wherein closing the NO switch causes the charging current and the discharging current to get diverted to least resistance path provided by the parallel combination of the closed NO switch and the second diode thereby bypassing the ESU, wherein, closing a discharging switch to discharge the ESU through a resistor to provide the electrical protection to the ESU, wherein the resistor is in series with the discharging switch, wherein the discharging switch is another NO switch; wherein the electrical protection is provided to the ESU by opening the first NC switch to disconnect the ESU from the main power line and by closing the NO switch to bypass the ESU from the main power line, providing the electrical protection to the ESU by operating a second NC switch connected in series with the first NC switch and a third NC switch connected in series with the ESU in combination; and providing the electrical protection to the ESU by opening the second NC switch to disconnect the ESU and the discharging circuit from the main power line and opening the third switch after opening of the second NC switch and discharging of the ESU through the resistor.
7 . The method according to claim 6 , further comprising: providing the electrical protection to the ESU by opening the third NC switch after discharging of the ESU through the resistor and opening the second NC switch after opening of the third NC switch.
8 . The method according to claim 6 , further comprising: opening the first NC switch connected in parallel to the resistor for causing the charging current to flow through the first diode or the second diode; closing the NO switch for discharging the ESU; and opening the second NC switch connected in between the ESU and the parallel combination of the resistor and the first NC switch for disconnecting the ESU from the main power line, when the ESU is discharged.
9 . The method according to claim wherein the first NC switch, the second NC switch, the third NC switch, the NO switch, and the discharging switch are of same or different types and connectable in series or parallel.
10 . The method according to claim 6 , further comprising: maintaining an uninterrupted current flow for rest of system other than the ESU during the bypassing, wherein the ESU is at least one of a battery unit or a supercapacitor.
11 . A module for connecting an Energy Storage Unit (ESU) to a main power line, the module comprising: a first main terminal configured to be connected to the main power line; a second main terminal configured to be connected to the main power line, wherein the second main terminal is configured for a lower electric potential than the first main terminal; a first ESU terminal configured to be connected to a positive terminal of the ESU; a second ESU terminal configured to be connected to a negative terminal of the ESU; a second NC switch connected in series with the first NC switch; and a third NC switch connected in series with the ESU, wherein a combination of the second NC switch and the third NC switch is configured to disconnect the ESU and the discharging circuit from the main power line thereby achieving electrical protection for the ESU, wherein the second NC switch is configured to be opened to disconnect the ESU and the discharging circuit from the main power line; and the third NC switch is configured to be opened after opening of the second NC switch and discharging of the ESU through the resistor, thereby achieving electrical protection for the ESU ( 10 ); and an electrical protection circuit ( 100 ) according to claim 1 .
12 - 23 . (canceled)

Description

TECHNICAL FIELD The present disclosure generally relates to energy storage units. More particularly, it relates to providing an electrical protection circuit for an energy storage unit, ESU. BACKGROUND In general, an energy storage sector consists of several different branches of mediums/energy storage units, ESUs, to store energy. The ESUs include batteries, supercapacitors, or the like. In an event of a fault condition (for example, current overloading, rapid discharge, under voltage, or the like), the ESUs have to be protected. An electrical protection circuit can be used to protect an ESU. The protection circuit can implement a method of electrical protection for protecting the ESU. However, while protecting the energy storage unit electrically, the ESU behaves differently depending on an implemented method of electrical protection. Also, while protecting the ESU, consequences such as thermal runaway, arcing, venting, fire, or the like, can cause short-circuit. Further, in the prior art, for protecting different types of ESUs, different types of electrical protection circuits can be used, as the electrical protection circuit may not implement a single method of electrical protection for the different types of ESUs. For example, if a bypass protection method is implemented, then there may be possibility for protecting the supercapacitor depending on impedance of the bypass protection method. On the contrary, the battery may not be protected by implementing the bypass protection method due to thermal runaway. In addition, while protecting the ESU, if an electrical system uses opening/breaking devices, the electrical system may have an open circuit, which can cause very high over-voltage. SUMMARY Consequently, there is a need for a universal electrical protection circuit for protecting different types of ESUs by considering functionalities/features, which can be applicable for all the types of ESUs. It is therefore an object of the present disclosure to provide an electrical protection circuit for an energy storage unit, ESU, to mitigate, alleviate, or eliminate all or at least some of the above-discussed drawbacks of presently known solutions. This and other objects are achieved by means of an electrical protection circuit, as defined in the appended claims. The term exemplary is in the present context to be understood as serving as an instance, example or illustration. According to a first aspect of the present disclosure, an electrical protection circuit for connecting an energy storage unit, ESU, to a main power line is provided. The electrical protection circuit comprises a first main terminal configured to be connected to the main power line, a second main terminal configured to be connected to the main power line, wherein the second main terminal is configured for a lower electric potential than the first main terminal. The first ESU terminal configured to be connected to a positive terminal of the ESU and a second ESU terminal configured to be connected to a negative terminal of the ESU. The first main terminal is connected to the first ESU terminal via a first normally closed, NC, switch. The electrical protection circuit comprises a first diode with an anode connected to the first main terminal and a cathode connected to the first ESU terminal. A parallel combination of the first NC switch and the first diode forms a closed path for a charging current and a discharging current flowing between the main power line and the ESU during operation. The first main terminal is connected to the second main terminal via a normally open, NO, switch, and a second diode being connected in parallel with the NO switch with a cathode connected to the first main terminal, and an anode connected to the second main terminal. The first NC switch is configured to be opened thereby to disconnect the ESU from the main power line. The NO switch is configured to be closed thereby to bypass the ESU from the main power line in order to achieve electrical protection for the ESU. Thus, with the proposed topology, controllable and safe electrical protection circuit is provided, which combines disconnection and bypassing functionalities for providing electrical protection to the ESU. In some embodiments, the electrical protection circuit comprises a discharging circuit. The discharging circuit comprises a resistor in series with a discharging switch. The discharging circuit is connected between the first ESU terminal and the second ESU terminal. The discharging switch is a NO switch. The discharging switch is configured to be closed thereby to discharge the ESU through the resistor in order to achieve the electrical protection for the ESU. Advantageously, the proposed electrical protection circuit utilizes discharging functionality along with the disconnection and bypassing functionalities for providing electrical protection to the ESU. Further, the electrical protection circuit disclosed herein may act as universal protection