ENERGY STORAGE DEVICE, METHOD FOR ENERGY STORAGE DEVICE TO DETERMINE WHETHER CONVERTER DEVICE CONNECTED THERETO HAS NEUTRAL LINE, AND POWER SUPPLY SYSTEM

An energy storage device, a method for an energy storage device to determine whether a converter device connected thereto has a neutral line, and a power supply system are provided. The energy storage device includes a connection terminal, a neutral line switch, an energy storage unit and a control unit. The control unit is adapted to: obtain, when the energy storage device is in a shutdown state and the converter device is in a state of charging the energy storage device, two port voltages of the energy storage device when a preset condition is satisfied, and determine whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, the neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese patent application No. 202311090950.3 filed on Aug. 28, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

As a power supply system, in an uninterruptible power supply, an energy storage device and a converter device are connected. The energy storage device is charged through the converter device when the utility power is normal, and direct-current (DC) power of the energy storage device is converted to the utility power through the converter device when the utility power is abnormal.

The converter unit is available in two models, one with a neutral line and the other without the neutral line. In order to match different models of converter devices, the energy storage device is generally configured with a neutral line output terminal. When the converter device has the neutral line, a positive terminal, a negative terminal and a neutral line terminal of the converter device are respectively connected to a positive output terminal, a negative output terminal, and the neutral line output terminal of the energy storage device. When the converter device does not have the neutral line, the positive terminal and the negative terminal of the converter device are respectively connected to the positive output terminal and the negative output terminal of the energy storage device. Therefore, operation of the energy storage device varies when the converter device has the neutral line or does not have the neutral line. In a practical application, cables of the converter device and the energy storage device would be connected in advance, but the energy storage device can not automatically identify whether the converter device has the neutral line. An on-site user needs to manually turn on the energy storage device and control its operation after determining whether there is the neutral line, which cannot achieve the automatic operation, and is time-consuming and laborious.

SUMMARY

The disclosure relates to the field of power supply, and in particular to an energy storage device, a method for an energy storage device to determine whether a converter device connected thereto has a neutral line, and a power supply system.

The purpose of the disclosure is to overcome the above defects or problems described in the background, and to provide an energy storage device, a method for an energy storage device to determine whether a converter device connected thereto has a neutral line, and a power supply system, which may detect whether the converter device has the neutral line.

In order to achieve the above purpose, the disclosure and relevant embodiments thereof adopt the following technical solutions, but are not limited thereto.

A first technical solution and relevant embodiments thereof relate to an energy storage device including a connection terminal, a neutral line switch, an energy storage unit and a control unit. The connection terminal includes a positive output terminal, a negative output terminal and a neutral line output terminal. The energy storage unit is adapted to be connected to the positive output terminal and the negative output terminal, and is further adapted to be connected to the neutral line output terminal through the neutral line switch. The control unit is adapted to: obtain, when the energy storage device is in a shutdown state and the converter device is in a state of charging the energy storage device, two port voltages of the energy storage device when a preset condition is satisfied, and determine whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, the neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off. The port voltages are voltages between the neutral line output terminal and the positive output terminal or voltages between the neutral line output terminal and the negative output terminal.

DESCRIPTION OF REFERENCE NUMERALS

Energy storage device100; positive output terminal11; negative output terminal12; neutral line output terminal13; energy storage unit20; first DC power supply module21; first DC power supply sub-module211; second DC power supply module22; second DC power supply sub-module221; first switch S1; second switch S2; third switch S3; neutral line switch S0; voltage dividing unit30; voltage dividing resistor R; voltage dividing switch Sr; control unit40; voltage collector50; and converter device200.

DETAILED DESCRIPTION

In order to achieve the above purpose, the disclosure and relevant embodiments thereof adopt the following technical solutions, but are not limited thereto.

A first technical solution and relevant embodiments thereof relate to an energy storage device including a connection terminal, a neutral line switch, an energy storage unit and a control unit. The connection terminal includes a positive output terminal, a negative output terminal and a neutral line output terminal. The energy storage unit is adapted to be connected to the positive output terminal and the negative output terminal, and is further adapted to be connected to the neutral line output terminal through the neutral line switch. The control unit is adapted to: obtain, when the energy storage device is in a shutdown state and the converter device is in a state of charging the energy storage device, two port voltages of the energy storage device when a preset condition is satisfied, and determine whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, the neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off. The port voltages are voltages between the neutral line output terminal and the positive output terminal or voltages between the neutral line output terminal and the negative output terminal.

A second technical solution is based on the first technical solution and is a preferred embodiment of the first technical solution. In the second technical solution, the energy storage device further includes a voltage collector. Either the positive output terminal or the negative output terminal is defined as a detection output terminal. The two port voltages are respectively a maximum voltage value and a minimum voltage value between the neutral line output terminal and the detection output terminal detected by the voltage collector during a set period. If a difference between the maximum voltage value and the minimum voltage value is within the preset range, the neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off.

A third technical solution is based on the first technical solution and is a preferred embodiment of the first technical solution. In the third technical solution, the energy storage device further includes a voltage collector and a voltage dividing unit. Either the positive output terminal or the negative output terminal is defined as the detection output terminal, and either the positive output terminal or the negative output terminal is defined as a connection output terminal. The voltage dividing unit is connected in series between the neutral line output terminal and the connection output terminal, and is adapted to establish a path between the neutral line output terminal and the connection output terminal. The two port voltages are respectively a first voltage between the neutral line output terminal and the detection output terminal, which is detected by the voltage collector when the path between the neutral line output terminal and the connection output terminal exists, and a second voltage between the neutral line output terminal and the detection output terminal, which is detected by the voltage collector when the path between the neutral line output terminal and the connection output terminal does not exist. If a difference between the first voltage and the second voltage is within the preset range, the neutral line switch is switched on; otherwise, the neutral line switch is switched off.

A fourth technical solution is based on the third technical solution and is a preferred embodiment of the third technical solution. In the fourth technical solution, the voltage dividing unit includes a voltage dividing resistor and a voltage dividing switch connected in series. The voltage dividing switch establishes the path between the neutral line output terminal and the connection output terminal when the voltage dividing switch is switched on, and the path between the neutral line output terminal and the connection output terminal does not exist when the voltage dividing switch is switched off.

A fifth technical solution is based on the fourth technical solution and is a preferred embodiment of the fourth technical solution. In the fifth technical solution, when the detection output terminal is the positive output terminal, if the connection output terminal is the positive output terminal, the first voltage is less than the second voltage, and the difference between the first voltage and the second voltage is not within the preset range, the control unit controls the neutral line switch to be switched off; otherwise, the control unit controls the neutral line switch to be switched on. If the connection output terminal is the negative output terminal, the first voltage is greater than the second voltage, and the difference between the first voltage and the second voltage is greater than a first threshold, the control unit controls the neutral line switch to be switched off; otherwise, the control unit controls the neutral line switch to be switched on. When the detection output terminal is the negative output terminal, if the connection output terminal is the positive output terminal, the first voltage is greater than the second voltage, and the difference between the first voltage and the second voltage is greater than the first threshold, the control unit controls the neutral line switch to be switched off; otherwise, the control unit controls the neutral line switch to be switched on. If the connection output terminal is the negative output terminal, the first voltage is less than the second voltage, and the difference between the first voltage and the second voltage is greater than the first threshold, the control unit controls the neutral line switch to be switched off; otherwise, the control unit controls the neutral line switch to be switched on.

A sixth technical solution is based on any one of the second to fifth technical solutions, and is a preferred embodiment of the second to fifth technical solutions. In the sixth technical solution, the energy storage unit includes a first DC power supply module and a second DC power supply module with equal voltages. The first DC power supply module and the second DC power supply module are adapted to be connected in series or in parallel. The neutral line switch is connected in series between a negative terminal of the first DC power supply module and the neutral line output terminal, or between a positive terminal of the second DC power supply module and the neutral line output terminal. The control unit is further adapted to switch on the neutral line switch when the first DC power supply module and the second DC power supply module are connected in series and it is determined that the converter device has a neutral line.

A seventh technical solution is based on the sixth technical solution and is a preferred embodiment of the sixth technical solution. In the seventh technical solution, the energy storage unit further includes a series-parallel switch module. The series-parallel switch module includes a first switch for connecting the first DC power supply module and the second DC power supply module in series, a second switch for connecting a positive terminal of the first DC power supply module and the positive terminal of the second DC power supply module in parallel, and a third switch for connecting the negative terminal of the first DC power supply module and a negative terminal of the second DC power supply module in parallel. The control unit is adapted to obtain an operating voltage and an operating current of the converter device, and control, when the operating voltage is greater than a first set value and the energy storage device is in a discharge state, the first switch to be switched on to connect the first DC power supply module and the second DC power supply module in series. The control unit further controls, when the operating current is greater than a second set value and the energy storage device is in the discharge state, the second switch and the third switch to be switched on to connect the first DC power supply module and the second DC power supply module in parallel.

An eighth technical solution is based on the seventh technical solution and is a preferred embodiment of the seventh technical solution. In the eighth technical solution, the first DC power supply module includes N first DC power supply sub-modules, the second DC power supply module includes M second DC power supply sub-modules, and N and M are positive integers. The series-parallel switch module includes, when N is greater than 1, a fourth switch unit for achieving series connection of the first DC power supply sub-modules and a fifth switch unit for achieving parallel connection of the first DC power supply sub-modules. The series-parallel switch module includes, when M is greater than 1, a seventh switch unit for achieving series connection of the second DC power supply sub-modules and an eighth switch unit for achieving parallel connection of the second DC power supply sub-modules. When the operating voltage is greater than the second set value, the energy storage device is in the discharge state and N is greater than 1, the control unit controls the number of the first DC power supply sub-modules and the second DC power supply sub-modules to be connected according to the operating voltage. When the operating current is greater than the first set value, the energy storage device is in the discharge state and M is greater than 1, the control unit controls the number of the first DC power supply sub-modules and the second DC power supply sub-modules to be connected according to the operating current. The control unit is adapted to shut down the energy storage unit when an operation requirement of the converter device changes, and switch, after a set period according to obtained information, a connection manner of the first DC power supply module and the second DC power supply module, a connection manner of the first DC power supply sub-modules, a connection manner of the second DC power supply sub-modules, and switching-on and switching-off of the neutral line switch.

A ninth technical solution relates to a method for an energy storage device to determine whether a converter device connected thereto has a neutral line. The energy storage device is provided with a positive output terminal, a negative output terminal and a neutral line output terminal. The method includes the following operations. A wiring between the energy storage device and the converter device is completed. When the energy storage device is in a shutdown state and the converter device is in a state of charging the energy storage device, two port voltages of the energy storage device when a preset condition is satisfied are obtained, and it is determined whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, the neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off. The port voltages are voltages between the neutral line output terminal and the positive output terminal or voltages between the neutral line output terminal and the negative output terminal.

A tenth technical solution and relevant embodiments thereof relates to a power supply system including a converter device and an energy storage device of any one of the first to eighth technical solutions. The converter device is a first converter device or a second converter device electrically coupled to the energy storage device. The first converter device includes a neutral potential point, and the second converter device does not include the neutral potential point.

As can be seen from the above description of the disclosure and specific embodiments thereof, compared to some implementations, the technical solutions of the disclosure and relevant embodiments thereof have the following beneficial effects by adopting the following technical means.

From continuous observation, experimentation and research, the applicant knows that in the existing technical solutions, the reason for the technical problem that the energy storage device cannot operate automatically is that the energy storage device cannot determine whether the converter device has the neutral line and thus manual intervention in the energy storage device is required after it is determined whether the converter device has the neutral line.

In the first technical solution and the relevant embodiments thereof, the wiring of the energy storage device and the converter device is firstly completed. At this time, since the energy storage device does not know whether the converter device has the neutral line, the energy storage device is in the shutdown state to ensure output safety of the energy storage device. The energy storage device is charged through the converter device, and the output terminal of the energy storage device is also electrified. The two port voltages of the energy storage device are obtained when the preset condition is satisfied, and it is determined whether the change of the voltage difference between the two port voltages is within the preset range when the preset condition is satisfied. If the result is yes, it is determined that the converter device has the neutral line and the neutral line switch is controlled to be switched on; otherwise, the converter device does not have the neutral line and the neutral line switch is controlled to be switched off. The port voltages are the voltages between the neutral line output terminal and the positive output terminal, or the voltages between the neutral line output terminal and the negative output terminal. The reason is as follows. When the converter device has the neutral line, the positive and negative voltages of the converter device are controlled separately, and the port voltages are basically unchanged. When the converter device does not have the neutral line, the difference between the positive and negative voltages of the converter device is stable, and thus the port voltages would change to different degrees under different detection conditions. Therefore, it may be determined whether the converter device has the neutral line by detecting the change of the port voltages under different conditions. The neutral line switch would be switched on after the neutral line has been detected, and thus the neutral line output terminal of the energy storage device is conductive; otherwise, the neutral line output terminal is not conductive. In this way, the energy storage device may match the converter device with the neutral line and the converter device without the neutral line, so that the energy storage device may be automatically adapted to different types of converter devices after operation. It is to be understood by those skilled in the art that when the neutral line switch is switched on, the voltage between the positive output terminal and the neutral line output terminal is equal to the voltage between the neutral line output terminal and the negative output terminal.

In the second technical solution and the relevant embodiments thereof, when the converter device has the neutral line, the port voltage between the neutral line output terminal and the detection output terminal is basically unchanged, that is, the maximum voltage value and the minimum voltage value are basically equal within the set period. When the converter device does not have the neutral line, the voltage between the neutral line output terminal and the detection output terminal fluctuates, that is, there exist a maximum voltage value and a minimum voltage value within the set period, and the difference between the two would exceed the preset range. In this way, it may be determined that the converter device does not have the neutral line and thus the neutral line switch is switched off. Such determination method is simple and easy to implement.

In the third technical solution and the relevant embodiments thereof, the first voltage between the neutral line output terminal and the detection output terminal of the energy storage device when the path between the neutral line output terminal and the connection output terminal exists, and the second voltage between the neutral line output terminal and the detection output terminal of the energy storage device when the path between the neutral line output terminal and the connection output terminal does not exist, are detected. If the difference between the first voltage and the second voltage exceeds the preset range, it is determined that the converter device connected thereto does not have the neutral line; otherwise, the converter device has the neutral line. The reason is as follows. When the converter device has the neutral line, the positive and negative voltages of the converter device are controlled separately, and thus the detected voltage between the neutral line output terminal and the detection output terminal does not change whether or not the path between the neutral line output terminal and the connection output terminal exists. When the converter device does not have the neutral line, the difference between the positive and negative voltages of the converter device is stable, a leakage current would be formed after the path between the neutral line output terminal and the connection output terminal is formed, so that the voltage corresponding to the detection output terminal changes. Therefore, the energy storage device may determine whether the converter device connected thereto has the neutral line by comparing the change of the difference between the first voltage and the second voltage, and thus control the neutral line switch to be switched on or off. Such determination method is simple to operate and easy to implement. When the difference between the first voltage and the second voltage is compared, both the first voltage and the second voltage correspond to the detection output terminal. However, the connection output terminal and the detection output terminal may be the same or different. The reason is as follows. When the converter device does not have the neutral line, the change of the voltage of the positive output terminal is necessarily accompanied by the change of the voltage of the negative output terminal. Therefore, even if the detection output terminal and the connection output terminal are different, it is still possible to determine whether there is a change before and after the existence of the path corresponding to the connection output terminal. The voltage dividing unit is disposed to establish the path between the neutral line output terminal and the connection output terminal, which is inexpensive, easy to operate and safe to use.

In the fourth technical solution and the relevant embodiments thereof, the path is formed by switching on the voltage dividing switch, and the path is disconnected by switching off the voltage dividing switch, which are easy to control.

In the fifth technical solution and the relevant embodiments thereof, several determination cases are described where the connection output terminal and the detection output terminal are the same and different, and the change of the voltage may be detected for each case. When the detection output terminal is the positive output terminal, if the connection output terminal is the positive output terminal, the positive voltage decreases due to the leakage current after the path is formed, so that the first voltage is less than the second voltage; if the connection output terminal is the negative output terminal, the negative voltage decreases due to the leakage current after the path is formed, so that the voltage between the neutral line output terminal and the negative output terminal decreases. Since the difference between the positive voltage and the negative voltage is unchanged, the positive voltage increases, so that the first voltage is greater than the second voltage. When the detection output terminal is the negative output terminal, if the connection output terminal is the positive output terminal, the positive voltage decreases due to the leakage current after the path is formed. Since the difference between the positive voltage and the negative voltage does not change, the voltage between the neutral line output terminal and the negative output terminal increases, so that the first voltage is greater than the second voltage; if the connection output terminal is the negative output terminal, the negative voltage decreases due to the leakage current after the path is formed, so that the voltage between the neutral line output terminal and the negative output terminal decreases, and the first voltage is less than the second voltage.

In the sixth technical solution and the relevant embodiments thereof, the control unit is further adapted to switch on the neutral line switch when the first DC power supply module and the second DC power supply module are connected in series and it is determined that the converter device has the neutral line, which ensures the automatic operation of the energy storage device.

In the seventh technical solution and the relevant embodiments thereof, the control unit controls series-parallel switching of the first DC power supply module and the second DC power supply module according to the operating voltage and operating current of the converter device, so that the energy storage device may further be adapted to the operation requirement of the converter device. Compared to manually adjusting series-parallel connection of the first DC power supply module and the second DC power supply module, the energy storage device may switch in real time, and operation is more flexible. When the converter device requires a large voltage, the first DC power supply module and the second DC power supply module are connected in series by controlling the first switch to be switched on, which enables the energy storage device to output a large output voltage. When the converter device not only requires the large voltage but also has the neutral line, the first DC power supply module and the second DC power supply module are connected in series by controlling the first switch to be switched on, and the neutral line switch is switched on, so that the energy storage device is enabled to output a large output voltage and to have the neutral line. When the converter device requires a large current, the first DC power supply module and the second DC power supply module are connected in parallel by controlling the second switch and the third switch to be switched on, which enables the energy storage device to output the large output current.

In the eighth technical solution and the relevant embodiments thereof, for different operation requirements of the converter device (e.g. the converter device requires a large voltage but the value of the large voltage is not the same, and the converter device requires a large current but the value of the large current is not the same), as long as it is ensured that voltages of the first DC power supply module and the second DC power supply module are equal, the first DC power supply module may be enabled to have different output currents and output voltages by combining series-parallel connection of the first DC power supply sub-modules in the first DC power supply module, and the second DC power supply module may also be enabled to have different output currents and output voltages by combining series-parallel connection of the second DC power supply sub-modules in the second DC power supply module. For example, when the first DC power supply module includes four first DC power supply sub-modules, the four first DC power supply sub-modules may be connected in series by the fourth switch unit to output a first voltage value. Alternatively, two of the four first DC power supply sub-modules may be connected in series as a group by the cooperation of the fourth switch unit and the fifth switch unit, and then the two groups may be connected in parallel to form the first DC power supply module having a second voltage value. Alternatively, only one or two first DC power supply sub-modules are connected according to the requirement of the converter device. Therefore, the eighth technical solution may further satisfy a variety of operation requirements of the converter device. When the converter device is replaced, the requirement of the converter device would change. In such case, firstly, the energy storage unit is shut down, and after determining the configuration and requirement of the converter device, the control unit performs control to switch the connection manner of the first DC power supply module and the second DC power supply module, the connection manner of the first DC power supply sub-modules, the connection manner of the second DC power supply sub-modules, and the switching-on and switching-off of the neutral line switch, which avoids confusion between the previous operating mode and the next operating mode of the energy storage unit, so that the switching of the connection manner of the first DC power supply module and the second DC power supply module is safe and reliable.

The technical effect of the ninth technical solution is basically equivalent to that of the first technical solution, with the difference that the ninth technical solution only relates to how to determine whether the converter device unit has the neutral line.

The technical effect of the tenth technical solution is equivalent to that of any of the first to eighth technical solutions.

The technical solutions in the embodiments of the disclosure would be clearly and completely described below in combination with the drawings in the embodiments of the disclosure. It is apparent that the described embodiments are preferred embodiments of the disclosure and should not be regarded as an exclusion of other embodiments. Based on the embodiments of the disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the disclosure.

In the claims, specification and aforementioned drawings of the disclosure, unless otherwise explicitly limited, the terms “first”, “second”, “third”, or the like, are used to distinguish different objects, and are not used to describe a particular order.

In the claims, specification and aforementioned drawings of the disclosure, unless otherwise explicitly limited, orientation terms, for example, the terms “center”, “transverse”, “longitudinal”, “horizontal”, “vertical”, “top”, “bottom”, “inside”, “outside”, “above”, “below”, “front”, “back”, “left”, “right”, “clockwise”, “anti-clockwise”, or the like, are used to indicate orientation or positional relationships which are based on the orientation and positional relationships shown in the drawings, and are only for the convenience of recounting the disclosure and simplifying the description, instead of indicating or implying that the device or element referred to necessarily has a specific orientation or is constructed and operated with a specific orientation, and therefore should not be understood as a restriction on the specific scope of protection of the disclosure.

In the claims, specification and aforementioned drawings of the disclosure, unless otherwise explicitly limited, the term “fixed connection” should be understood in a broad sense, i.e., any connection manner that does not involve a displacement relationship or a relative rotation relationship between the two, which includes non-detachable fixed connection, detachable fixed connection, integrated connection, and fixed connection through other devices or elements.

In the claims, specification and aforementioned drawings of the disclosure, the terms “include”, “have” and variations thereof are intended to denote “including but not limited to”.

First Embodiment

Referring toFIGS.1-2,FIGS.1-2illustrate a power supply system including an energy storage device100and a converter device200. The energy storage device100is provided with a positive output terminal11, a negative output terminal12and a neutral line output terminal13. The converter device200is a first converter device200or a second converter device200electrically coupled to the energy storage device100. Referring toFIG.1, the first converter device200includes a neutral potential point and is used to be connected to the positive output terminal11, the negative output terminal12and the neutral line output terminal13. Referring toFIG.2, the second converter device200does not include the neutral potential point and is used to be connected to only the positive output terminal11and the negative output terminal12.

Referring toFIGS.1-2, the energy storage device100includes a connection terminal, an energy storage unit20, a neutral line switch S0, a voltage collector50and a control unit40. The units and modules described in the present disclosure may be implemented by circuits.

The connection terminal includes the positive output terminal11, the negative output terminal12and the neutral line output terminal13. Either the positive output terminal11or the negative output terminal12is defined as a connection output terminal. Either the positive output terminal11or the negative output terminal12is defined as a detection output terminal. The connection terminal is an external electrical connection port of the entire energy storage device100.

The energy storage unit20is adapted to be connected to the positive output terminal11and the negative output terminal12, and is further adapted to be connected to the neutral line output terminal13through the neutral line switch S0. Specifically, the energy storage unit20includes a first DC power supply module21and a second DC power supply module22with equal voltages. The first DC power supply module21and the second DC power supply module22are adapted to be connected in series or in parallel. The neutral line switch S0is connected in series between a negative terminal of the first DC power supply module21and the neutral line output terminal13, or between a positive terminal of the second DC power supply module22and the neutral line output terminal13.

The energy storage unit20further includes a series-parallel switch module. The series-parallel switch module includes a first switch S1for connecting the first DC power supply module21and the second DC power supply module22in series, a second switch S2for connecting a positive terminal of the first DC power supply module21and the positive terminal of the second DC power supply module22in parallel, and a third switch S3for connecting the negative terminal of the first DC power supply module21and a negative terminal of the second DC power supply module22in parallel.

The first DC power supply module21includes N first DC power supply sub-modules211, and the second DC power supply module22includes M second DC power supply sub-modules221. N and M are positive integers.

The energy storage unit20may be in the form of an energy storage box including a battery pack, a first DC/DC transformation unit and a second DC/DC transformation unit. Each energy storage unit20is provided with a positive terminal, a negative terminal and a neutral line terminal, which are used to be connected to the positive output terminal11, the negative output terminal12and the neutral line output terminal13, respectively. Low voltage sides of the first DC/DC transformation unit and the second DC/DC transformation unit are connected to the battery pack, and high voltage sides of the first DC/DC transformation unit and the second DC/DC transformation unit are provided with positive terminals and negative terminals to form the first DC power supply module21and the second DC power supply module22, respectively. In such case, a converter device200may correspond to multiple energy storage units20, and the multiple energy storage units20are connected in parallel. Both the series-parallel switch modules and the neutral line switches S0are located in the energy storage box, and the number of neutral line switches S0corresponds to the number of energy storage units20.

Of course, in another implementation, the energy storage unit20may be in the form of an energy storage cabinet including multiple energy storage modules connected in parallel. Each energy storage module is in the form of an energy storage box including a battery pack, the first DC/DC transformation unit and the second DC/DC transformation unit. The low voltage sides of the first DC/DC transformation unit and the second DC/DC transformation unit are connected to the battery pack. Positive terminals of the corresponding first DC/DC transformation unit and the second DC/DC transformation unit in each energy storage module are respectively connected in parallel to form the positive terminals of the first DC power supply module21and the second DC power supply module22. Negative terminals of the corresponding first DC/DC transformation unit and the second DC/DC transformation unit in each energy storage module are respectively connected in parallel to form the negative terminals of the first DC power supply module21and the second DC power supply module22. In such case, the number of energy storage units20corresponds to the number of converter devices200. Both the series-parallel switch module and the neutral line switch S0are located outside the energy storage box, and only one group of series-parallel switch modules and one group of neutral line switches S0are needed to be disposed. The energy storage unit20inFIGS.1-2is in the form of the energy storage cabinet.

In the practical application, the first DC/DC transformation unit includes N first DC/DC converters, and the second DC/DC transformation unit includes M second DC/DC converters. Input terminals of the first DC/DC converters and the second DC/DC converters are connected to the battery pack. Each of high voltage sides of the first DC/DC converters and the second DC/DC converters is provided with a respective positive terminal and a respective negative terminal. Each of the first DC/DC converter and the second DC/DC converter forms a respective one of the first DC power supply sub-module211and the second DC power supply sub-module221.

Referring toFIG.3, when N is greater than 1, the series-parallel switch module includes a fourth switch unit (switch S4inFIG.3) for achieving series connection of the first DC power supply sub-modules211and a fifth switch unit (switches S5and S6inFIG.3) for achieving parallel connection of the first DC power supply sub-modules211. When M is greater than 1, the series-parallel switch module includes a seventh switch unit (switch S7inFIG.3) for achieving series connection of the second DC power supply sub-modules221and an eighth switch unit (switches S8and S9inFIG.3) for achieving parallel connection of the second DC power supply sub-modules221. It is to be understood that in another implementation, the first DC power supply module21may include N (N>1) first DC power supply sub-modules211, and the second DC power supply module22may include one second DC power supply sub-module221. Alternatively, the first DC power supply module21may include one first DC power supply sub-module, and the second DC power supply module22may include M (M>1) second DC power supply sub-modules.

The control unit40is adapted to: obtain, when the energy storage device100is in a shutdown state and the converter device200is in a state of charging the energy storage device100, two port voltages of the energy storage device100when a preset condition is satisfied, and determine whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, the neutral line switch S0is controlled to be switched on; otherwise, the neutral line switch S0is controlled to be switched off. The port voltages are voltages between the neutral line output terminal13and the positive output terminal11or voltages between the neutral line output terminal13and the negative output terminal12.

In the embodiment, the two port voltages are respectively a maximum voltage value and a minimum voltage value between the neutral line output terminal13and the detection output terminal detected by the voltage collector50during a set period. If a difference between the maximum voltage value and the minimum voltage value is within the preset range, the neutral line switch S0is controlled to be switched on; otherwise, the neutral line switch S0is controlled to be switched off.

Regarding the converter device200, in addition to the difference in the existence of the neutral line, there is further a difference in the operation requirement. Some converter devices200require high currents and some converter devices200require high voltages. Therefore, the energy storage device100of the embodiment may further be optimally self-adaptive to the operation requirement of the converter device200.

The control unit40is adapted to obtain an operating voltage and an operating current of the converter device200, and control, when the operating voltage is greater than a first set value and the energy storage device100is in a discharge state, the first switch S1to be switched on to connect the first DC power supply module21and the second DC power supply module22in series. The control unit40further controls, when the operating current is greater than a second set value and the energy storage device100is in the discharge state, the second switch S2and the third switch S3to be switched on to connect the first DC power supply module21and the second DC power supply module22in parallel.

When both N and M are greater than 1, when the operating voltage is greater than the first set value, the energy storage device100is in the discharge state and N is greater than 1, the control unit40controls the number of the first DC power supply sub-modules211and the second DC power supply sub-modules221to be connected according to the operating voltage. When the operating current is greater than the first set value, the energy storage device100is in the discharge state and M is greater than 1, the control unit40controls the number of the first DC power supply sub-modules211and the second DC power supply sub-modules221to be connected according to the operating current. For example, the converter device200requires large voltages but the values of the large voltages are not the same, or the converter device200requires large currents but the values of the large currents are not the same, as long as voltages of the first DC power supply module21and the second DC power supply module22are ensured to be equal, the first DC power supply module21may be enabled to have different output currents and output voltages by combining series-parallel connection of the first DC power supply sub-modules211in the first DC power supply module21, and the second DC power supply module22may also be enabled to have different output currents and output voltages by combining series-parallel connection of the second DC power supply sub-modules221in the second DC power supply module22.

For example, both the first converter device200and the second converter device200require a large voltage, but the required large voltage value at this time is less than the voltage value when the first DC power supply sub-modules211are connected in series, when the second DC power supply sub-modules221are connected in series, and when the first DC power supply module21and the second DC power supply module22are connected in series. In such case, two of four first DC power supply sub-modules211may be connected in series as a group by cooperation of the fourth switch unit and the fifth switch unit, and then the two groups may be connected in parallel to form the first DC power supply module21having a second voltage value. Similarly, the second DC power supply module22is enabled to output the second voltage value.

The control unit40is adapted to shut down the energy storage unit20when the operation requirement of the converter device200changes, and switch a connection manner of the first DC power supply module21and the second DC power supply module22, a connection manner of the first DC power supply sub-modules211, a connection manner of the second DC power supply sub-modules221, and switching-on and switching-off of the neutral line switch S0after the set period according to obtained information (whether the converter device has the neutral line, and the operating voltage and operating current of the converter device).

In the embodiment, a method for an energy storage device100to determine whether a converter device200connected thereto has a neutral line specifically includes the following operations.

In operation S1, a wiring between the energy storage device100and the converter device200is completed. The energy storage device100is enabled to be in a shutdown state and the converter device200is enabled to be in a state of charging the energy storage device100.

In the operation, the wiring of the energy storage device100and the converter device200is firstly completed. At this time, the energy storage device100does not know whether the converter device200has the neutral line, and thus the energy storage device100is in the shutdown state to ensure output safety of the energy storage device100. The energy storage device100is charged through the converter device200, and an output terminal of the energy storage device100is also electrified.

In operation S2, two port voltages of the energy storage device100when a preset condition is satisfied are obtained, and it is determined whether a change of a voltage difference between the two port voltages is within a preset range when the preset condition is satisfied. If the result is yes, a neutral line switch is controlled to be switched on; otherwise, the neutral line switch is controlled to be switched off.

In the operation, in the embodiment, a voltage value between a neutral line output terminal13and a positive output terminal11of the energy storage device100during a set period is detected by a voltage collector50and sent to a control unit40. The voltage collector50always collects the voltage between the neutral line output terminal13and the positive output terminal11. The largest voltage value is a maximum voltage value and the smallest voltage value is a minimum voltage value. The control unit40receives the voltage value, compares the difference between the maximum voltage value and the minimum voltage value, and determines whether the difference is within the preset range. If so, it is determined that the converter device200connected thereto does not have the neutral line, and the neutral line switch S0is switched off; otherwise, the converter device200has the neutral line, and the neutral line switch S0is switched on.

In the embodiment, when the converter device200has the neutral line, positive and negative voltages of the converter device200are controlled separately, and a port voltage between the neutral line output terminal13and a detection output terminal is basically unchanged, that is, the maximum voltage value and the minimum voltage value within the set period are basically equal. When the converter device200does not have the neutral line, the difference between the positive and negative voltages of the converter device200is stable, and the voltage between the neutral line output terminal13and the detection output terminal fluctuates. Therefore, there would be the maximum voltage value and the minimum voltage value within the set period, and the difference between the two would exceed the preset range. In this way, it may be determined that the converter device200does not have the neutral line and thus the neutral line switch S0is switched off. Such determination method is simple and easy to implement. The neutral line switch S0would be switched on after the neutral line has been detected, and thus the neutral line output terminal13of the energy storage device100is conductive; otherwise, the neutral line output terminal13is not conductive. In this way, the energy storage device100can be matched with the converter device200with the neutral line and the converter device200without the neutral line, so that the energy storage device100may be automatically adapted to different types of converter devices200after operation.

In the embodiment, the control unit40controls series-parallel switching of a first DC power supply module21and a second DC power supply module22according to an operating voltage and an operating current of the converter device200, so that the energy storage device100may further be adapted to an operation requirement of the converter device200. Compared to manually adjusting the series-parallel connection of the first DC power supply module21and the second DC power supply module22, the energy storage device100may switch in real time, and the operation is more flexible.

When the converter device200is replaced, the requirement of the converter device200will change. In such case, the energy storage unit20is shut down firstly, and after determining the configuration and requirement of the converter device, the control unit40controls to switch a connection manner of the first DC power supply module21and the second DC power supply module22, a connection manner of first DC power supply sub-modules211, a connection manner of second DC power supply sub-modules221, and switching-on and switching-off of the neutral line switch S0, which avoids confusion between the previous operating mode and the next operating mode of the energy storage unit20, so that the switching of the connection manner of each DC power supply module21is safe and reliable.

Second Embodiment

The second embodiment is basically the same as the first embodiment. The difference is that, referring toFIG.4, a voltage dividing unit30and a voltage collector50are further included.

The voltage dividing unit30is connected in series between the neutral line output terminal13and the connection output terminal, and is adapted to establish a path between the neutral line output terminal13and the connection output terminal. In the embodiment, both the connection output terminal and the detection output terminal are the positive output terminal11. The voltage dividing unit30includes a voltage dividing resistor R and a voltage dividing switch Sr connected in series. The voltage dividing switch Sr establishes the path between the neutral line output terminal13and the connection output terminal when the voltage dividing switch Sr is switched on, and the path between the neutral line output terminal13and the connection output terminal does not exist when the voltage dividing switch Sr is switched off.

The voltage collector50collects the voltage between the neutral line output terminal13and the positive output terminal11and transmits the voltage to the control unit40. The control unit40communicates with the series-parallel switch module, the neutral line switch S0, the voltage dividing switch Sr, the voltage collector50and the converter device200.

The control unit40is adapted to, when the wiring between the energy storage unit20and the converter device200is completed, the energy storage unit20is in the shutdown state and the converter device200is in the state of charging the energy storage unit20, detect the first voltage between the neutral line output terminal13and the positive output terminal11of the energy storage unit20when the path between the neutral line output terminal13and the positive output terminal11exists, and the second voltage between the neutral line output terminal13and the positive output terminal11of the energy storage unit20when the path between the neutral line output terminal13and the positive output terminal11does not exist. If the difference between the first voltage and the second voltage exceeds the first threshold, it is determined that the converter device200connected thereto does not have the neutral line (i.e., it is determined that the converter device200is the second converter device200), and the neutral line switch S0is controlled to be switched off. Otherwise, the converter device200has the neutral line (it is determined that the converter device200is the first converter device200), and the neutral line switch S0is controlled to be switched on.

The method for the energy storage device100to determine whether the converter device200connected thereto has the neutral line specifically includes the following operations.

In operation S1, the wiring between the energy storage device100and the converter device200is completed. The energy storage device100is enabled to be in the shutdown state and the converter device200is enabled to be in the state of charging the energy storage device100.

In the operation, the wiring of the energy storage device100and the converter device200is firstly completed. At this time, the energy storage device100does not know whether the converter device200has the neutral line, and the energy storage device100is in the shutdown state to ensure the output safety of the energy storage device100. The energy storage device100is charged through the converter device200, and the output terminal of the energy storage device100is also electrified.

In operation S2, the first voltage when the path between the neutral line output terminal13and the positive output terminal11of the energy storage device100exists, and the second voltage when the path does not exist, are detected by the voltage collector50, and are sent to the control unit40.

In the operation, the voltage collector50always collects the voltage between the neutral line output terminal13and the positive terminal output terminal11. When the control unit40controls the dividing switch Sr to be switched on, the path between the neutral line output terminal13and the positive output terminal11is established. When the control unit40controls the dividing switch Sr to be switched off, the path between the neutral line output terminal13and the positive output terminal11is disconnected.

In operation S3, the control unit40receives the first voltage and the second voltage, and compares the difference between the first voltage and the second voltage. If the first voltage is less than the second voltage and the difference between the first voltage and the second voltage exceeds the first threshold, it is determined that the converter device200connected thereto does not have the neutral line; otherwise, the converter device200has the neutral line.

The reason is as follows. When the converter device200has the neutral line, the positive and negative voltages of the converter device200are controlled separately, and the detected voltage between the neutral line output terminal13and the positive output terminal11does not change when the path between the neutral line output terminal13and the connection output terminal exists or does not exist. When the converter device200does not have the neutral line, the difference between the positive and negative voltages of the converter device200is stable, and a leakage current would be formed after the path between the neutral line output terminal13and the connection output terminal is formed, so that the voltage corresponding to the connection output terminal changes. In the embodiment, correspondingly, the connection output terminal is the positive output terminal11. After the path between the positive output terminal11and the neutral output terminal13is formed, the positive voltage decreases due to the leakage current, and the first voltage is less than the second voltage. Therefore, the energy storage device100may determine whether the converter device200connected thereto has the neutral line by comparing the change of the difference between the first voltage and the second voltage. As can be seen, such determination method is simple to operate and easy to implement.

On the basis of the aforementioned method, the energy storage device100switches on the neutral line switch S0when it is determined that the converter device200has the neutral line, and switches off the neutral line switch S0when it is determined that the converter device200does not have the neutral line. Therefore, the energy storage device100is enabled to be adaptive, in a series state, to the converter device200configured with the neutral line and the converter device200that is not configured with the neutral line.

Third Embodiment

The power supply system of the third embodiment is basically the same as that of the second embodiment. The difference is that, referring toFIG.5, the connection output terminal is the negative output terminal12, and the voltage dividing unit30of the energy storage device100is connected in series between the neutral line output terminal13and the negative output terminal12. When the first voltage is greater than the second voltage and the difference between the first voltage and the second voltage is greater than the first threshold, the control unit40determines that the converter device200connected thereto does not have the neutral line and controls the neutral line switch S0to be switched off; otherwise, the converter device200has the neutral line and the neutral line switch S0is controlled to be switched on.

In the embodiment, after the voltage dividing unit30forms the path between the neutral line output terminal13and the negative output terminal12, the negative voltage decreases due to the leakage current, and the voltage between the neutral line output terminal13and the negative output terminal12decreases. Since the difference between the positive voltage and the negative voltage does not change, the positive voltage increases, and the first voltage is greater than the second voltage.

Fourth Embodiment

The power supply system of the fourth embodiment is basically the same as that of the second embodiment. Referring toFIG.6, the difference is that the detection output terminal is the negative terminal output12, that is, the voltage collector50of the energy storage device100collects the first voltage when the path between the neutral line output terminal13and the negative output terminal12exists, and collects the second voltage when the path does not exist. When the first voltage is greater than the second voltage and the difference between the first voltage and the second voltage is greater than the first threshold, the control unit40determines that the converter device200connected thereto does not have the neutral line and controls the neutral line switch S0to be switched off; otherwise, the converter device200has the neutral line and the neutral line switch S0is controlled to be switched on.

In the embodiment, after the voltage dividing unit30forms the path between the neutral line output terminal13and the positive output terminal11, the positive voltage decreases due to the leakage current. Since the difference between the positive voltage and the negative voltage does not change, the voltage between the neutral line output terminal13and the negative output terminal12increases, and the first voltage is greater than the second voltage.

Fifth Embodiment

The power supply system of the fifth embodiment is basically the same as that of the fourth embodiment. The difference is that, referring toFIG.7, the connection output terminal is the negative output terminal, and the voltage dividing unit30of the energy storage device100is connected in series between the neutral line output terminal13and the negative output terminal12. When the first voltage is less than the second voltage and the difference between the first voltage and the second voltage is greater than the first threshold, the control unit40determines that the converter device200connected thereto does not have the neutral line and controls the neutral line switch S0to be switched off; otherwise, the converter device200has the neutral line and the neutral line switch S0is controlled to be switched on.

In the embodiment, after the voltage dividing unit30forms the path between the neutral line output terminal13and the negative output terminal12, the negative voltage decreases due to the leakage current. Therefore, the voltage between the neutral line output terminal13and the negative output terminal12decreases, and the first voltage is less than the second voltage.

The aforementioned description of the specification and the embodiments is used to explain the scope of protection of the disclosure, but does not constitute a limitation of the scope of protection of the disclosure. Through the enlightenment of the disclosure or the aforementioned embodiments, all the modifications, equivalent substitutions or other improvements to the embodiments of the disclosure or some of the technical features thereof that can be obtained by those of ordinary skill in the art by combining common knowledge, ordinary technical knowledge in the art and/or some implementations through logical analysis, inference or limited experiments shall be included in the scope of protection of the disclosure.