Energy storage system, and protection device and protection method thereof

Abstract

This energy storage system comprises: a battery; a first battery terminal and a second battery terminal connected to the battery; a first inverter terminal and a second inverter terminal connected to an inverter; a switch connected between the second battery terminal and the second inverter terminal; and a protection circuit which determines whether to open the switch on the basis of a difference between a first voltage sensed by the first inverter terminal and a second voltage sensed by the second inverter terminal, and the first voltage and the second voltage.

Description

Energy storage system and its protection device and protection method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0163660, dated November 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] The disclosure relates to an energy storage system and a protection device and method thereof.

[0004] Energy storage systems (ESS), which store and then deliver stored power, are being used in a variety of fields. For example, ESS can be used to store excess power generated by power plants and provide power during temporary power shortages. Furthermore, compact ESS systems can be used in buildings, factories, and homes to prepare for power outages or reduce peak power consumption. ESS can also be used to store power generated from renewable energy sources and utilize the stored power when needed.

[0005] Inverters are used to store power in energy storage systems and supply power to loads. Recently, as power generation systems using high voltages, such as solar power generation, are increasingly connected to inverters, a failure in the inverter could result in high voltages being supplied to the energy storage system, potentially destroying the system.

[0006] Some embodiments may provide an energy storage system and a protection device and protection method thereof capable of protecting the energy storage system in the event of a failure of an inverter.

[0007] In some embodiments, the energy storage system may include a battery, a first battery terminal and a second battery terminal to which the battery is connected, a first inverter terminal and a second inverter terminal to which an inverter is connected, a switch connected between the second battery terminal and the second inverter terminal, and a protection circuit that determines whether to open the switch based on a difference between a first voltage sensed at the first inverter terminal and a second voltage sensed at the second inverter terminal, and the first voltage and the second voltage.

[0008] In some embodiments, a protection device of an energy storage system including a battery and a switch controlling a connection between the battery and an inverter may include a voltage divider circuit that divides a voltage of a first inverter terminal connected to a first terminal of the inverter to output a first voltage and divides a voltage of a second inverter terminal connected to a second terminal of the inverter to output a second voltage, an adder that calculates a difference between the first voltage and the second voltage, a first comparator that compares the difference between the first voltage and the second voltage with a first reference voltage, a second comparator that compares the first voltage with a second reference voltage, a third comparator that compares the second voltage with a third reference voltage, a logic circuit that performs a logic operation on a first output signal of the first comparator, a second output signal of the second comparator, and a third output signal of the third comparison circuit, and a switch control circuit that controls the switch based on a fourth output signal of the logic circuit.

[0009] In some embodiments, a method for protecting an energy storage system including a battery and a switch controlling a connection between the battery and an inverter may include the steps of: detecting a voltage of a first inverter terminal connected to a first terminal of the inverter and outputting a first voltage; detecting a voltage of a second inverter terminal connected to a second terminal of the inverter and outputting a second voltage; comparing a difference between the first voltage and the second voltage with a first reference voltage; comparing the first voltage with a second reference voltage; comparing the second voltage with a third reference voltage; and opening the switch when the difference between the first voltage and the second voltage is greater than the first reference voltage, the first voltage is greater than the second reference voltage, or the second voltage is greater than the third reference voltage.

[0010] FIG. 1 is a diagram showing an example of a power supply system according to some embodiments.

[0011] FIG. 2 is a diagram illustrating an example of an energy storage system according to some embodiments.

[0012] FIG. 3 is a diagram showing an example of a protection circuit of an energy storage system according to some embodiments.

[0013] FIG. 4 is a diagram showing an example of a protection circuit of an energy storage system according to another embodiment.

[0014] FIG. 5 is a flowchart illustrating an example of a method for protecting an energy storage system according to some embodiments.

[0015] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description are omitted for clarity of description, and similar parts are designated with similar reference numerals throughout the specification.

[0016] When a component is said to be "connected" to another component, it should be understood that while it may be directly connected to that other component, there may be other components intervening. Conversely, when a component is said to be "directly connected" to another component, it should be understood that there are no other components intervening.

[0017] In the description below, expressions written in the singular may be interpreted as singular or plural, unless explicit expressions such as “one” or “single” are used.

[0018] In the flowchart described with reference to the drawing, the order of operations may be changed, several operations may be merged, some operations may be split, and certain operations may not be performed.

[0019] FIG. 1 is a diagram showing an example of a power supply system according to some embodiments.

[0020] Referring to FIG. 1, the power supply system may include a power generation device (110), an energy storage system (or energy storage device) (120), an inverter (130), a system (140), and a load (150).

[0021] The power generation device (110) can produce electrical energy. The power generation device (110) can be, for example, a solar power generation system, a wind power generation system, a tidal power generation system, or a geothermal power generation system, but is not limited thereto. For example, when a solar power generation system is used, the power generation device (110) can include a solar cell array that converts solar energy into electrical energy. The solar cell array includes a plurality of solar cell modules, and the solar cell modules can convert solar energy into electrical energy by connecting a plurality of solar cell cells in series or parallel to generate a predetermined voltage and current.

[0022] The energy storage system (120) can charge electric energy supplied from the power generation device (110), discharge the charged electric energy, and supply it to the grid (140) or the load (150). For example, when the grid (140) or the load (150) is under light load, the energy storage system (120) can be charged by receiving idle power from the power generation device (110). When the grid (140) or the load (150) is overloaded, the energy storage system (120) can discharge the charged power and supply power to the grid (140) or the load (150).

[0023] The inverter (130) can convert direct current power into alternating current power. The inverter (130) can convert direct current power supplied by the power generation device (110) or direct current power supplied by the energy storage system (120) into alternating current power. In some embodiments, the inverter (130) may be a three-phase inverter. In some embodiments, when the power generation device (110) uses a high voltage, the inverter (130) may include an inverter (131) that converts direct current power into alternating current power and a DC / DC converter (132) that converts direct current power supplied by the power generation device (110) into direct current power. The energy storage system (120) can charge the direct current power supplied from the DC / DC converter (132). The inverter (131) can convert the DC power supplied from the energy storage system (120) or the DC power supplied from the DC / DC converter (132) into AC power and supply it to the grid (140) or load (150).

[0024] The system (140) may be a power network connected to power plants, substations, transmission and distribution systems, etc. The load (150) may be a device that consumes power.

[0025] The energy storage system (120) may include a protection circuit (or protection device) (121) that detects a failure of the inverter (130) and protects the energy storage system (120) in the event of a failure of the inverter (130). In some embodiments, the protection circuit (121) may cut off the electrical connection between the energy storage system (120) and the inverter (130).

[0026] FIG. 2 is a diagram illustrating an example of an energy storage system according to some embodiments.

[0027] Referring to FIG. 2, the energy storage system (200) may include a battery (210), a switch (220), and a protection circuit (230). In some embodiments, the protection circuit (230) may be a battery management system of the energy storage system (200) or may be included in the battery management system.

[0028] The battery (210) may be a secondary battery. The battery (210) may be, for example, a lithium battery, such as a lithium ion battery or a lithium ion polymer battery, or a nickel battery, such as a nickel-cadmium (NiCd) battery or a nickel-metal hydride (NiMH) battery. In some embodiments, the battery (210) may include an assembly of multiple battery cells, a battery module in which multiple assemblies are connected in series or parallel, a battery pack (or battery rack) in which multiple battery modules are connected in series or parallel, or multiple battery packs in series or parallel.

[0029] The positive electrode of the battery (210) may be connected to the positive battery terminal (B+) of the energy storage system (200), and the negative electrode of the battery (210) may be connected to the negative battery terminal (B-) of the energy storage system (200). Either the positive battery terminal (B+) or the negative battery terminal (B-) may be referred to as a first battery terminal, and the other may be referred to as a second battery terminal. In some embodiments, the positive battery terminal (B+) and the negative battery terminal (B-) may be referred to as a positive battery socket (B+) and a negative battery socket (B-), respectively. The positive inverter terminal (INV+) of the energy storage system (200) may be connected to the positive terminal of an inverter (e.g., 130 of FIG. 1), and the negative inverter terminal (INV-) of the energy storage system (200) may be connected to the negative terminal of the inverter (130). Either the positive inverter terminal (INV+) or the negative inverter terminal (INV-) may be referred to as the first inverter terminal, and the other as the second inverter terminal. Furthermore, either the positive terminal or the negative terminal of the inverter may be referred to as the first terminal, and the other as the second terminal. The positive inverter terminal (INV+) and the negative inverter terminal (INV-) may be referred to as the positive inverter socket (INV+) and the negative inverter socket (INV-), respectively.

[0030] In some embodiments, the positive terminal and the negative terminal of the inverter (130) may be the positive output and the negative output, respectively, of the DC / DC converter (132) of the inverter (130). In some embodiments, the positive terminal and the negative terminal of the inverter (130) may be the positive input and the negative input, respectively, of the inverter (131).

[0031] A switch (220) may be connected between a battery terminal of the energy storage system (200) and an inverter terminal of the energy storage system (200). In some embodiments, as illustrated in FIG. 2, the switch (220) may be connected between a negative battery terminal (B-) and a negative inverter terminal (INV-). In some embodiments, the switch (220) may be connected between a positive battery terminal (B+) and a positive inverter terminal (INV+). In some embodiments, the switch (220) may include a switch connected between a positive battery terminal (B+) and a positive inverter terminal (INV+) and a switch connected between a negative battery terminal (B-) and a negative inverter terminal (INV-). In some embodiments, the switch (220) may be a conductor formed as a relay.

[0032] The ground of the energy storage system (200) may be connected to a ground terminal (GND). The ground terminal (GND) may be referred to as a ground socket (GND). In some embodiments, the ground terminal (GND) may be connected to the chassis ground of the energy storage system (200).

[0033] The protection circuit (230) receives the voltage of the positive inverter terminal (INV+) and the voltage of the negative inverter terminal (INV-), diagnoses whether the inverter (130) is faulty based on the voltage of the positive inverter terminal (INV+) and the voltage of the negative inverter terminal (INV-), and can open the switch (220) if the inverter (130) is faulty. For example, if a higher voltage than the voltage to be actually provided from the inverter (130) (e.g., the DC / DC converter (132) of FIG. 1) is supplied, the protection circuit (230) can diagnose the inverter (130) as faulty based on the voltage of the positive inverter terminal (INV+) and the voltage of the negative inverter terminal (INV-), and can open the switch (220). Or, if a short circuit occurs in the line connecting the inverter (130) and the system (140), the protection circuit (230) can diagnose a failure (short circuit) of the inverter (130) based on the voltage of the positive inverter terminal (INV+) and the voltage of the negative inverter terminal (INV-) and open the switch (220).

[0034] In some embodiments, a fuse (240) may be connected between the positive battery terminal (B+) and the positive inverter terminal (INV+). In some embodiments, a fuse (250) may be connected between the negative battery terminal (B-) and the negative inverter terminal (INV-).

[0035] FIG. 3 is a diagram showing an example of a protection circuit of an energy storage system according to some embodiments.

[0036] Referring to FIG. 3, a protection circuit (300) may be connected to a positive inverter terminal (INV+) and a negative inverter terminal (INV-) of an energy storage system, and may include an adder (310), a comparator (320, 330, 340), a logic circuit (350), and a switch control circuit (360).

[0037] The adder (310) can calculate the difference (Vip-Vin) between the voltage detected at the positive inverter terminal (INV+) (referred to as “positive inverter voltage”) (Vip) and the voltage detected at the negative inverter terminal (INV-) (referred to as “negative inverter voltage”) (Vin). The adder (310) may be called a subtracter.

[0038] The comparator (320) can compare the difference (Vip-Vin) between the positive inverter voltage (Vip) and the negative inverter voltage (Vin) calculated by the adder (310) with the reference voltage (or first reference voltage) (Vref1). When the difference (Vip-Vin) between the positive inverter voltage (Vip) and the negative inverter voltage (Vin) is greater than the reference voltage (Vref1), the comparator (320) can output an output signal (or first output signal) (S1) having a first predetermined level (or first level). When the difference (Vip-Vin) between the positive inverter voltage (Vip) and the negative inverter voltage (Vin) is not greater than the reference voltage (Vref1), the comparator (320) can output an output signal (S1) having a second level different from the first predetermined level. Depending on the setting of the reference voltage (Vref1), if the difference (Vip-Vin) between the positive inverter voltage (Vip) and the negative inverter voltage (Vin) is greater than the reference voltage (Vref1), it can be interpreted that the difference (Vip-Vin) between the positive inverter voltage (Vip) and the negative inverter voltage (Vin) is greater than the reference voltage (Vref1).

[0039] The comparator (330) can compare the positive inverter voltage (Vip) with the reference voltage (or second reference voltage) (Vref2). In some embodiments, since a three-phase inverter can be used, the positive inverter voltage (Vip) compared by the comparator (330) can be the positive inverter voltage (Vip) relative to the ground terminal (e.g., GND in FIG. 2). That is, the comparator (330) can compare the voltage obtained by subtracting the voltage of the ground terminal (GND) from the positive inverter voltage (Vip) with the reference voltage (Vref2). The comparator (330) can output an output signal (or second output signal) (S2) having a first predetermined level when the positive inverter voltage (Vip) (e.g., the voltage obtained by subtracting the voltage of the ground terminal (GND) from the positive inverter voltage (Vip)) is greater than the reference voltage (Vref2). The comparator (330) can output an output signal (S2) having a second level different from the first predetermined level when the positive inverter voltage (Vip) is not greater than the reference voltage (Vref2). Depending on the setting of the reference voltage (Vref2), when the positive inverter voltage (Vip) is greater than the reference voltage (Vref2), it can be interpreted that the positive inverter voltage (Vip) is equal to or greater than the reference voltage (Vref2).

[0040] The comparator (340) can compare the negative inverter voltage (Vin) with the reference voltage (or third reference voltage) (Vref3). In some embodiments, since a three-phase inverter can be used, the negative inverter voltage (Vip) compared by the comparator (340) can be the negative inverter voltage (Vin) relative to the ground terminal (GND). That is, the comparator (340) can compare the voltage obtained by subtracting the voltage of the ground terminal (GND) from the negative inverter voltage (Vin) with the reference voltage (Vref3). The comparator (340) can output an output signal (or third output signal) (S3) having a first predetermined level when the negative inverter voltage (Vip) (e.g., the voltage obtained by subtracting the voltage of the ground terminal (GND) from the negative inverter voltage (Vin)) is greater than the reference voltage (Vref3). In this case, the magnitudes of the negative inverter voltage (Vip) and the reference voltage (Vref3) may be the absolute values ​​of the negative inverter voltage (Vip) and the reference voltage (Vref3), respectively. The comparator (340) may output an output signal (S3) having a second level different from the first predetermined level when the negative inverter voltage (Vin) is not greater than the reference voltage (Vref3). Depending on the setting of the reference voltage (Vref2), when the positive inverter voltage (Vip) is greater than the reference voltage (Vref2), it may be interpreted that the positive inverter voltage (Vip) is greater than or equal to the reference voltage (Vref2).

[0041] The logic circuit (350) can output an output signal (S4) based on the output signals (S1, S2, S3) output from the comparators (320, 330, 340). The logic circuit (350) can output an output signal (S4) by performing a logic operation on the output signals (S1, S2, S3) output from the comparators (320, 330, 340). The logic circuit (350) can output a control signal having a second predetermined level (or a third level) when at least one output signal among the output signals (S1, S2, S3) output from the comparators (320, 330, 340) has a first predetermined level. The logic circuit (350) can output a control signal having a fourth level different from the second predetermined level when the output signal (S1, S2, S3) output from the comparator (320, 330, 340) has a second level.

[0042] In some embodiments, when the first predetermined level is a high level as a logic level, the logic circuit (350) may include an OR gate, and the second predetermined level may be a high level. In some embodiments, when the first predetermined level is a high level as a logic level, the logic circuit (350) may include a NOR gate, and the second predetermined level may be a low level. In some embodiments, when the first predetermined level is a low level as a logic level, the logic circuit (350) may include an AND gate, and the second predetermined level may be a low level. In some embodiments, when the first predetermined level is a low level as a logic level, the logic circuit (350) may include a NAND gate, and the second predetermined level may be a high level.

[0043] The switch control circuit (360) can open a switch (30) connecting a battery terminal of the energy storage system and an inverter terminal of the energy storage system in response to an output signal (S4) of a second predetermined level.

[0044] In this way, when an abnormality occurs in the voltage supplied from the inverter, the protection circuit (300) detects a failure of the inverter and opens a switch (30) that controls the connection between the battery of the energy storage system and the inverter, thereby preventing the failure of the inverter from affecting the energy storage system. In addition, the protection circuit determines whether there is an abnormality in the difference between the positive inverter voltage and the negative inverter voltage, and in the positive inverter voltage and the negative inverter voltage, respectively, so that the energy storage system can be protected even when a three-phase inverter is connected to the energy storage system.

[0045] In some embodiments, since the inverter can output a high voltage, the protection circuit (300) may further include a voltage divider circuit (370) so that a low voltage can be used in the protection circuit (300). The voltage divider circuit (370) may include a first voltage divider circuit that divides the voltage of the positive inverter terminal (INV+) to output a positive inverter voltage (Vip) and a second voltage divider circuit that divides the voltage of the negative inverter terminal (INV-) to output a negative inverter voltage (Vin). The voltage divider circuit (370) may include, for example, a first voltage divider circuit including a plurality of resistors connected in series between the positive inverter terminal (INV+) and a ground terminal (GND), and a second voltage divider circuit including a plurality of resistors connected in series between the negative inverter terminal (INV-) and a ground terminal (GND).

[0046] In some embodiments, the protection circuit (300) may include a high voltage buffer (or first buffer) (381) and a low voltage buffer (or second buffer) (382). The high voltage buffer (381) may store the positive inverter voltage (Vip) detected by the voltage divider circuit (370), and the low voltage buffer (382) may store the negative inverter voltage (Vin) detected by the voltage divider circuit (370).

[0047] In some embodiments, the protection circuit (300) may further include a power management device (391) and / or a power management device (392). The power management device (391) may be connected to the positive battery terminal (B+) and the negative battery terminal (B-) to generate voltages used by the components of the protection circuit (300) based on the voltage of the battery. The power management device (391) may be connected to the positive inverter terminal (INV+) and the negative inverter terminal (INV-) to generate voltages used by the components of the protection circuit (300) based on the voltage supplied by the inverter. In some embodiments, the power management devices (391, 392) may include a DC / DC converter.

[0048] FIG. 4 is a diagram showing an example of a protection circuit of an energy storage system according to some embodiments.

[0049] Referring to FIG. 4, the protection circuit (400) may include an adder (410), a comparator (420, 430, 440), a logic circuit (450), and a switch control circuit (460). In some embodiments, the protection circuit (400) may further include a voltage divider circuit (470), a high voltage buffer (481), and a low voltage buffer (482). In some embodiments, the protection circuit (400) may further include a power management device (491 and / or 492). The adder (410), comparator (420, 430, 440), logic circuit (450), voltage divider circuit (470), high voltage buffer (481), low voltage buffer (482), and power management device (491, 492) operate identically or similarly to the adder (310), comparator (320, 330, 330), logic circuit (350), voltage divider circuit (370), high voltage buffer (381), low voltage buffer (382), and power management device (391, 392) described with reference to FIG. 3, and therefore, the description thereof is omitted.

[0050] The switch control circuit (460) may include a latch (461) and a driver (462). The latch (461) may output a control signal (S5) having a second predetermined level in response to an output signal (S4) having a second predetermined level from the logic circuit (450).

[0051] A switch (40) connecting a battery terminal of the energy storage system and an inverter terminal of the energy storage system may include a relay switch (41) and a relay coil (42).

[0052] A relay switch (41) may be connected between a battery terminal and an inverter terminal. A relay coil (42) may be provided to drive the relay switch (41). A driver (462) may be connected between a power source that supplies a supply voltage (Vs) and a first terminal of the relay coil (42), and a second terminal of the relay coil (42) may be connected to a terminal having a lower potential than the supply voltage (Vs) (e.g., a ground terminal (GND)). For convenience of explanation, the terminal having a lower potential than the supply voltage (Vs) will be described as a ground terminal (GND) hereinafter. The power source that supplies the supply voltage (Vs) may be, for example, a power management device (491 and / or 492).

[0053] The driver (462) controls the electrical connection between the power supplying the supply voltage (Vs) and the first terminal of the relay coil (42), and may be provided as a switch such as a transistor, for example. Such a driver (462) may be referred to as a high-side driver (HSD). When the power supplying the supply voltage (Vs) and the first terminal of the relay coil (42) are connected by the driver (462), a current flows through the relay coil (42), a magnetic field is generated by the current, and the contacts of the relay switch (41) are connected by the magnetic field, so that the switch (40) can be closed. The driver (462) can electrically cut off the power supplying the supply voltage (Vs) and the first terminal of the relay coil (42) in response to a control signal (S5) having a second predetermined level from the latch (461). Accordingly, the current flowing through the relay coil (42) is cut off, the contact of the relay switch (41) is broken, and the switch (40) can be opened.

[0054] In some embodiments, a first terminal of the relay coil (42) may be connected to a power source that supplies a supply voltage (Vs), and a driver (462) may be connected between a second terminal of the relay coil (42) and ground. This driver (462) may be referred to as a low-side driver (LSD). In some embodiments, the driver (462) may include a driver connected between the first terminal of the relay coil (42) and a power source that supplies the supply voltage (Vs) and a driver connected between the second terminal of the relay coil (42) and ground.

[0055] In this way, when an abnormality occurs in the voltage supplied from the inverter, the protection circuit (300) detects a failure of the inverter and opens a switch (30) that controls the connection between the battery of the energy storage system and the inverter, thereby preventing the failure of the inverter from affecting the energy storage system. In addition, the protection circuit determines whether there is an abnormality in the difference between the positive inverter voltage and the negative inverter voltage, and in the positive inverter voltage and the negative inverter voltage, respectively, so that the energy storage system can be protected even when a three-phase inverter is connected to the energy storage system.

[0056] FIG. 5 is a flowchart illustrating an example of a method for protecting an energy storage system according to some embodiments.

[0057] Referring to FIG. 5, when the energy storage system or inverter is powered on (S510), the protection circuit may be powered on (S520), and a switch controlling the connection between the battery of the energy storage system and the inverter may be closed (S530). In some embodiments, when the energy storage system is powered on, the power management device may provide power to the protection circuit using the voltage of the battery of the energy storage system. In some embodiments, when the inverter is powered on, the power management device may provide power to the protection circuit using the voltage of the inverter.

[0058] The protection circuit can determine whether the voltage of the inverter (i.e., the positive inverter voltage and the negative inverter voltage) satisfies a diagnostic condition (S540). In some embodiments, the diagnostic condition may include a first diagnostic condition in which a difference between the positive inverter voltage and the negative inverter voltage is greater than a first reference voltage, a second diagnostic condition in which the positive inverter voltage is greater than a second reference voltage, and / or a third diagnostic condition in which the negative inverter voltage is greater than a third reference voltage. In some embodiments, the positive inverter voltage compared to the second reference voltage may be the positive inverter voltage relative to a ground (e.g., chassis ground) of the energy storage system. In some embodiments, the negative inverter voltage compared to the third reference voltage may be the negative inverter voltage relative to a ground (e.g., chassis ground) of the energy storage system.

[0059] If at least one of the first diagnostic condition, the second diagnostic condition, and the third diagnostic condition is satisfied (S540: Yes), the protection circuit may open the switch (S550). In some embodiments, if the difference between the positive inverter voltage and the negative inverter voltage is greater than the first reference voltage, the positive inverter voltage is greater than the second reference voltage, or the negative inverter voltage is greater than the third reference voltage, the protection circuit may open the switch (S550). If the diagnostic condition is not satisfied (S540: No), the protection circuit may monitor the inverter voltage to determine whether the diagnostic condition is satisfied.

[0060] In some embodiments, the protection circuit may determine whether the inverter voltage satisfies a diagnostic release condition after opening the switch (S560). In some embodiments, the diagnostic release condition may include a condition in which a difference between the positive inverter voltage and the negative inverter voltage is not greater than a first reference voltage, a condition in which the positive inverter voltage is not greater than a second reference voltage, and a condition in which the negative inverter voltage is not greater than a third reference voltage. That is, when the difference between the positive inverter voltage and the negative inverter voltage is not greater than the first reference voltage, the positive inverter voltage is not greater than the second reference voltage, and the negative inverter voltage is not greater than the third reference voltage, the protection circuit may determine that the diagnostic release condition is satisfied (S560: Yes).

[0061] If the diagnostic release condition is met (S560: Yes), the protection circuit may turn off the power of the energy storage system to close the switch (S570) and then turn on the power of the energy storage system again (S510). In some embodiments, if the diagnostic release condition is met (S560: Yes), the protection circuit may turn off the power of the inverter (S570) and then turn on the power of the inverter again (S510).

[0062] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. Battery, The first battery terminal and the second battery terminal to which the above battery is connected, The first inverter terminal and the second inverter terminal to which the inverter is connected, a switch connected between the second battery terminal and the second inverter terminal, and A protection circuit that determines whether to open the switch based on the difference between the first voltage detected at the first inverter terminal and the second voltage detected at the second inverter terminal, and the first voltage and the second voltage An energy storage system comprising:

2. In paragraph 1, An energy storage system, wherein the protection circuit determines a first diagnostic condition in which a difference between the first voltage and the second voltage is greater than a first reference voltage, a second diagnostic condition in which the first voltage is greater than a second reference voltage, and a third diagnostic condition in which the second voltage is greater than a third reference voltage, and opens the switch when at least one of the first diagnostic condition, the second diagnostic condition, and the third diagnostic condition is satisfied.

3. In paragraph 2, An energy storage system, wherein the protection circuit turns off power to the energy storage system and then turns it back on if, after opening the switch, the difference between the first voltage and the second voltage is not greater than the first reference voltage, the first voltage is not greater than the second reference voltage, and the second voltage is not greater than the third reference voltage.

4. In paragraph 1, The above inverter is a three-phase inverter, The first voltage is a voltage relative to the ground of the energy storage system, and the second voltage is a voltage relative to the ground of the energy storage system. Energy storage system.

5. In paragraph 1, The above protection circuit An adder for calculating the difference between the first voltage and the second voltage, A first comparator for comparing the difference between the first voltage and the second voltage with a first reference voltage; A second comparator for comparing the first voltage and the second reference voltage, A third comparator for comparing the second voltage with the third reference voltage, A logic circuit that performs a logic operation on the first output signal of the first comparator, the second output signal of the second comparator, and the third output signal of the third comparison circuit, and A switch control circuit that controls the switch based on the fourth output signal of the above logic circuit. An energy storage system comprising:

6. In paragraph 5, The above switch A relay switch connected between the second battery terminal and the second inverter terminal, and It includes a relay coil that drives the above relay switch, The above switch control circuit A latch that outputs a control signal in response to the fourth output signal, and A driver connected to the terminal of the above relay coil and disconnecting the connection between the relay coil and the power source in response to a predetermined level of the above control signal. An energy storage system comprising:

7. In paragraph 5, The first comparator outputs the first output signal having a first predetermined level when the difference between the first voltage and the second voltage is greater than the first reference voltage, The second comparator outputs the second output signal having the first predetermined level when the first voltage is greater than the second reference voltage, The third comparator outputs the third output signal having the first predetermined level when the second voltage is greater than the third reference voltage, The logic circuit outputs the fourth output signal having the second predetermined level when at least one of the first output signal, the second output signal and the third output signal has the first predetermined level. The above switch control circuit opens the switch in response to the second predetermined level of the fourth output signal. Energy storage system.

8. In paragraph 5, An energy storage system wherein the protection circuit further includes a voltage dividing circuit that divides the voltage of the first inverter terminal to output the first voltage and that divides the voltage of the second inverter terminal to output the second voltage.

9. A protection device for an energy storage system including a battery and a switch controlling the connection between the battery and an inverter, A voltage dividing circuit that divides the voltage of a first inverter terminal connected to a first terminal of the inverter to output a first voltage, and divides the voltage of a second inverter terminal connected to a second terminal of the inverter to output a second voltage. An adder for calculating the difference between the first voltage and the second voltage, A first comparator for comparing the difference between the first voltage and the second voltage with a first reference voltage; A second comparator for comparing the first voltage and the second reference voltage, A third comparator for comparing the second voltage with the third reference voltage; A logic circuit that performs a logic operation on the first output signal of the first comparator, the second output signal of the second comparator, and the third output signal of the third comparison circuit, and A switch control circuit that controls the switch based on the fourth output signal of the above logic circuit. A protective device including:

10. In Article 9, The first comparator outputs the first output signal having a first predetermined level when the difference between the first voltage and the second voltage is greater than the first reference voltage, The second comparator outputs the second output signal having the first predetermined level when the first voltage is greater than the second reference voltage, The third comparator outputs the third output signal having the first predetermined level when the second voltage is greater than the third reference voltage, The logic circuit outputs the fourth output signal having the second predetermined level when at least one of the first output signal, the second output signal and the third output signal has the first predetermined level. The above switch control circuit opens the switch in response to the second predetermined level of the fourth output signal. Protective device.

11. In paragraph 9, The logic circuit outputs the fourth output signal having a predetermined level when the first output signal indicates that the difference between the first voltage and the second voltage is greater than the first reference voltage, when the second output signal indicates that the first voltage is greater than the second reference voltage, or when the third output signal indicates that the second voltage is greater than the third reference voltage. The above switch control circuit opens the switch in response to the predetermined level of the fourth output signal. Protective device.

12. In paragraph 9, a first buffer storing the first voltage, and A second buffer storing the second voltage A protective device including:

13. In paragraph 9, The above inverter is a three-phase inverter, The first voltage is a voltage relative to the ground of the energy storage system, and the second voltage is a voltage relative to the ground of the energy storage system. Protective device.

14. A method for protecting an energy storage system including a battery and a switch controlling the connection between the battery and an inverter, A step of detecting the voltage of a first inverter terminal connected to the first terminal of the inverter and outputting a first voltage; A step of detecting the voltage of a second inverter terminal connected to the second terminal of the inverter and outputting a second voltage; A step of comparing the difference between the first voltage and the second voltage with the first reference voltage, A step of comparing the first voltage and the second reference voltage, a step of comparing the second voltage and the third reference voltage, and A step of opening the switch when the difference between the first voltage and the second voltage is greater than the first reference voltage, the first voltage is greater than the second reference voltage, or the second voltage is greater than the third reference voltage. A method of protection comprising:

15. In paragraph 14, A protection method further comprising the step of turning off power of the energy storage system and then turning it on again after opening the switch, if the difference between the first voltage and the second voltage is not greater than the first reference voltage, the first voltage is not greater than the second reference voltage, and the second voltage is not greater than the third reference voltage.

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