Capacity expansion energy storage unit and energy storage system

Abstract

The utility model provides a capacity expansion energy storage unit and an energy storage system, and the unit comprises a charging and discharging circuit, one end of which is connected with external equipment; and the plurality of power supply circuits are connected to the other end of the charging and discharging circuit in parallel, and the control end of each power supply circuit is used for receiving a control signal for changing the on-off state of the power supply circuit.

Description

Technical Field

[0001] This application relates to the technical field of energy storage systems, and particularly to an expanded energy storage unit and an energy storage system. Background Art

[0002] In the prior art, the DC side of a modular multilevel (Modular Multilevel Converter, MMC) system is usually composed of single cells or batteries formed by connecting single cells in series. Usually, the method of increasing the battery capacity is used to improve the system capacity, or the capacity and power are improved by paralleling the battery cells. However, in the traditional capacity increase method, the batteries are rigidly connected and cannot be flexibly configured according to the system requirements.

[0003] For example, when a certain single cell fails, the energy storage unit corresponding to the single cell cannot be normally connected to the circuit, resulting in a decrease in the system capacity. Although paralleling single cells can improve the system power, the inconsistency of the batteries will cause the circulating current problem between the single cells, affecting the state estimation and normal use of the batteries. Summary of the Utility Model

[0004] In view of this, the purpose of this application is to provide an expanded energy storage unit and an energy storage system, which can set multiple power supply circuits connected in parallel on the DC side of the charge and discharge circuit, and can send control signals to the control ends of the power supply circuits to control the on and off of the power supply circuits. It solves the problem of the decrease in the system capacity caused by the failure of a certain single cell, and achieves the technical effect of improving the stability of the system capacity. At the same time, through the control of the paralleled batteries, the flexible configuration of the maximum output power of the system is realized, and the technical effect of reducing the circulating current of the paralleled single cells is achieved.

[0005] In a first aspect, an embodiment of this application provides an expanded energy storage unit, where the expanded energy storage unit includes: a charge and discharge circuit, one end of the charge and discharge circuit is connected to an external device; a plurality of power supply circuits, the plurality of power supply circuits are connected in parallel to the other end of the charge and discharge circuit, and the control end of each power supply circuit is used to receive a control signal for changing the on and off state of the power supply circuit.

[0006] Optionally, each power supply circuit includes a first control switch and a battery connected in series, and the control end of the first control switch serves as the control end of the power supply circuit.

[0007] Optionally, each power supply circuit further includes a second control switch and a diode, where a first connection end of the second control switch is connected to a first connection end of the first control switch, a second connection end of the second control switch is connected to one end of the diode, and the other end of the diode is connected to a second connection end of the first control switch.

[0008] Optionally, the capacity expansion energy storage unit further includes a filter circuit, and the filter circuit is disposed between the other end of the charge and discharge circuit and the plurality of power circuits.

[0009] Optionally, the charge and discharge circuit includes a first bridge circuit and a second bridge circuit. One end of the first bridge circuit serves as the other end of the charge and discharge circuit, the other end of the first bridge circuit is connected to one end of the second bridge circuit, and the other end of the second bridge circuit serves as one end of the charge and discharge circuit.

[0010] Optionally, the first bridge circuit includes a third control switch and a fourth control switch. One end of the third control switch is connected to one end of the filter circuit, the other end of the third control switch is connected to one end of the fourth control switch, and the other end of the fourth control switch is connected to the other end of the filter circuit.

[0011] Optionally, the second bridge circuit includes a fifth control switch, a sixth control switch, a seventh control switch, and an eighth control switch. One end of the fifth control switch is connected to one end of the sixth control switch, the other end of the fifth control switch is connected to one end of the seventh control switch, the other end of the sixth control switch is connected to one end of the eighth control switch, and the other end of the seventh control switch is connected to the other end of the eighth control switch.

[0012] Optionally, one end of the fifth control switch is connected to the other end of the third control switch, the other end of the seventh control switch is connected to the other end of the fourth control switch, and the connection between the fifth control switch and the seventh control switch and the connection between the sixth control switch and the eighth control switch serve as the other end of the second bridge circuit.

[0013] In a second aspect, an embodiment of the present application further provides an energy storage system, and the energy storage system includes a bridge arm, and the bridge arm includes a plurality of capacity expansion energy storage units connected in series as described in the first aspect or any possible implementation manner of the first aspect above.

[0014] Optionally, the bridge arm is a single-phase bridge arm or a three-phase bridge arm.

[0015] An expanded energy storage unit and an energy storage system provided by an embodiment of the present application, the expanded energy storage unit includes: a charge and discharge circuit, one end of the charge and discharge circuit is connected to an external device; a plurality of power supply circuits, the plurality of power supply circuits are connected in parallel at the other end of the charge and discharge circuit, and the control end of each power supply circuit is used to receive a control signal for changing the on / off state of the power supply circuit. By arranging a plurality of power supply circuits connected in parallel on the DC side of the charge and discharge circuit, a control signal can be sent to the control end of the power supply circuit to control the on / off of the power supply circuit. It solves the problem of system capacity decline caused by a single battery failure, and achieves the technical effect of improving the stability of the system capacity. At the same time, through the control of parallel batteries, the maximum output power of the system can be flexibly configured, and the circulating current of parallel single batteries is reduced.

[0016] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0018] Figure 1 Shows a schematic structural diagram of an expanded energy storage unit provided by an embodiment of the present application.

[0019] Figure 2 Shows a schematic structural diagram of another expanded energy storage unit provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Usually, the components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, every other embodiment obtained by those of ordinary skill in the art without creative efforts belongs to the scope of protection of the present application.

[0021] In the prior art, there is generally only one battery pack on the DC side of the energy storage unit of the energy storage system. When the bus current of the energy storage system is too large, the battery pack may be burned out, resulting in the inability of the energy storage unit to continue working; if a fault occurs in the battery pack, the energy storage system can only bypass the energy storage unit, reducing the electric energy of the energy storage system; if the electric energy of the battery pack is consumed, the energy storage unit cannot supply power to the outside, resulting in a short power supply time for one energy storage unit.

[0022] In view of the above problems, the embodiments of the present application provide an expanded energy storage unit and an energy storage system, which can set a plurality of power supply circuits connected in parallel on the DC side of the charge and discharge circuit, and can send a control signal to the control end of the power supply circuit to control the on and off of the power supply circuit. It solves the problem of system capacity reduction caused by a single battery failure, and achieves the technical effect of improving the stability of system capacity. At the same time, through the control of parallel batteries, it realizes the flexible configuration of the maximum output power of the system and reduces the circulating current of parallel single batteries. The specific details are as follows:

[0023] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an expanded energy storage unit provided by the embodiments of the present application. As Figure 1 shown, the expanded energy storage unit provided by the embodiments of the present application includes: a charge and discharge circuit 101, one end of the charge and discharge circuit is connected to an external device; a plurality of power supply circuits 102, the plurality of power supply circuits are connected in parallel at the other end of the charge and discharge circuit, and the control end of each power supply circuit is used to receive a control signal for changing the on and off state of the power supply circuit.

[0024] That is to say, the expanded energy storage unit further includes a controller, which is configured to: send a first control signal to the control end of at least one target power supply circuit among the plurality of power supply circuits, and send a second control signal to the control ends of the other power supply circuits except the target power supply circuit among the plurality of power supply circuits, wherein the first control signal is used to control the on and off state of the power supply circuit to be in the on state, and the second control signal is used to control the on and off state of the power supply circuit to be in the off state. Furthermore, only the target power supply circuit is connected to the expanded energy storage unit. Thus, when the external device is an electrical device, the electric energy of the target power supply circuit is supplied to the electrical device through the charge and discharge circuit, and when the external device is a power supply device, the power supply device supplies power to the electric energy of the target power supply circuit through the charge and discharge circuit.

[0025] By setting a plurality of power supply circuits, and each power supply circuit can be controlled to be on or off, the capacity of the energy storage system can be increased by alternately using a single power supply circuit, and the power of the system can also be increased by controlling multiple power supply circuits to be connected in parallel.

[0026] As Figure 1, each power supply circuit 102 includes a first control switch Q1 and a battery BAT connected in series, and the control terminal of the first control switch serves as the control terminal of the power supply circuit.

[0027] That is to say, for each power supply circuit, the first connection terminal of the first control switch of the power supply circuit is connected to the other end of the charge and discharge circuit, the second connection terminal of the first control switch is connected to one end of the battery, the other end of the battery is connected to the other end of the charge and discharge circuit, and the control terminal of the first control switch is connected to the controller. Furthermore, by setting the first control switch, when a fault occurs in the system, the power supply circuit of the energy storage unit with the fault can be disconnected, so that other energy storage units without faults can continue to work. Moreover, the first control switch can also avoid the circulating current existing in the battery parallel structure and prevent the circulating current from affecting the battery life and the estimation accuracy of the battery state.

[0028] Furthermore, the controller is configured to: change the on / off state of the power supply circuit by sending a control signal to the control terminal of the first control switch. Thus, the controller can select the power supply circuit of the expanded energy storage unit to be connected and the bypassed power supply circuit. Furthermore, when there are faulty power supply circuits or power supply circuits whose electric energy has been consumed in multiple power supply circuits, the controller can bypass these power supply circuits to extend the usage time of the energy storage unit.

[0029] The controller can also be configured to: sequentially select one power supply circuit to be connected among multiple power supply circuits, and by sending a first control signal to the control terminal of this power supply circuit and a second control signal to the control terminals of other power supply circuits except the target power supply circuit among the multiple power supply circuits, so that the multiple power supply circuits are sequentially and cyclically connected to the expanded energy storage unit, thereby increasing the capacity and usage time of the energy storage unit.

[0030] The controller can also be configured to: control all the power supply circuits to be connected by sending a first control signal to the control terminals of all the power supply circuits, so as to increase the capacity and usage time of the energy storage unit, and can prevent damage to a single battery caused by excessive bus current. Among them, a single-phase bridge arm of the energy storage system includes multiple energy storage units connected in series, and the bus current refers to the current of the energy storage units connected in series.

[0031] Please refer to Figure 2 , Figure 2 , which is a schematic structural diagram of another expanded energy storage unit provided by the embodiment of the present application. As Figure 2 shown, each power supply circuit 102 further includes a second control switch Q2 and a diode D. Among them, the first connection terminal of the second control switch is connected to the first connection terminal of the first control switch, the second connection terminal of the second control switch is connected to one end of the diode, and the other end of the diode is connected to the second connection terminal of the first control switch.

[0032] That is, for each power supply circuit, after the first control switch and the battery of the power supply circuit are connected in series, the second control switch and the diode connected in series are then connected in parallel across the two ends of the first control switch.

[0033] Specifically, the diodes of multiple power supply circuits form an OR gate circuit. Thus, when the controller controls the first control switch of each power supply circuit to be turned off and the second control switch to be turned on, the OR gate circuit will select the power supply circuit with the highest voltage value as the target power supply circuit to be connected to the extended energy storage unit, and the other power supply circuits will not output electrical energy due to the reverse cut-off of the diodes. Thus, multiple power supply circuits can cyclically select the battery with the highest voltage value to be connected to the extended energy storage unit, realizing the uninterrupted and alternating use of multiple parallel power supply circuits to increase the capacity of the extended energy storage unit.

[0034] That is, during the discharge process of the extended energy storage unit, the target power supply circuit with the highest voltage value is connected to the extended energy storage unit and releases electrical energy. Thus, during the gradual use of the target power supply circuit, the voltage value of the battery decreases. When the voltage value of the battery of other power supply circuits is greater than the voltage value of the battery of the target power supply circuit, the other power supply circuits are used as the new target power supply circuits to be connected to the extended energy storage unit and continue to release electrical energy.

[0035] As Figure 2 shown, the extended energy storage unit further includes a filtering circuit, and the filtering circuit is arranged between the other end of the charge and discharge circuit and the multiple power supply circuits. The filtering circuit includes a filtering capacitor C, and the filtering capacitor is used for filtering the electrical energy between each power supply circuit and the charge and discharge circuit.

[0036] The charge and discharge circuit 101 includes a first bridge circuit 1011 and a second bridge circuit 1012. One end of the first bridge circuit serves as the other end of the charge and discharge circuit, the other end of the first bridge circuit is connected to one end of the second bridge circuit, and the other end of the second bridge circuit serves as one end of the charge and discharge circuit.

[0037] Among them, the first bridge circuit is a half-bridge circuit, and the second bridge circuit is a full-bridge circuit. That is, the charge and discharge form of converting between direct current and alternating current is realized through the combination of the half-bridge circuit and the full-bridge circuit. The half-bridge circuit is mainly responsible for handling the charging and discharging of direct current, and the full-bridge circuit is mainly responsible for generating alternating current and converting the alternating current into single-phase electricity.

[0038] During the discharging process, the half-bridge circuit converts the direct current of the battery into a mantou voltage waveform, and the full-bridge circuit inverts the mantou voltage waveform to generate an alternating current waveform for alternating current discharging. During the charging process, the full-bridge circuit inverts the received alternating current to generate a mantou voltage waveform with a positive level, and then the half-bridge circuit converts the mantou voltage waveform into an equivalent regulated voltage with a duty cycle to charge the battery.

[0039] The first bridge circuit includes a third control switch Q3 and a fourth control switch Q4. One end of the third control switch is connected to one end of the filter circuit, the other end of the third control switch is connected to one end of the fourth control switch, and the other end of the fourth control switch is connected to the other end of the filter circuit.

[0040] When the third control switch Q3 is closed and the fourth control switch Q4 is open, the voltage value at the other end of the first bridge circuit is the same as the voltage value of the battery BAT. When the third control switch Q3 is open and the fourth control switch Q4 is closed, the voltage value at the other end of the first bridge circuit is 0. Furthermore, the controller controls the third control switch Q3 and the fourth control switch Q4 to alternately close by outputting different control signals to the control terminals of the third control switch Q3 and the fourth control switch Q4, thereby changing the voltage value at the other end of the first bridge circuit.

[0041] The second bridge circuit includes a fifth control switch Q5, a sixth control switch Q6, a seventh control switch Q7, and an eighth control switch Q8. One end of the fifth control switch is connected to one end of the sixth control switch, the other end of the fifth control switch is connected to one end of the seventh control switch, the other end of the sixth control switch is connected to one end of the eighth control switch, and the other end of the seventh control switch is connected to the other end of the eighth control switch.

[0042] One end of the fifth control switch is connected to the other end of the third control switch, the other end of the seventh control switch is connected to the other end of the fourth control switch, and the connection between the fifth control switch and the seventh control switch and the connection between the sixth control switch and the eighth control switch serve as the other end of the second bridge circuit.

[0043] Among them, the voltage value at the other end of the second bridge circuit includes the following 4 results, namely forward connection, forward bypass, reverse bypass, and reverse connection. When the fifth control switch and the eighth control switch are closed and the sixth control switch and the seventh control switch are open, the second bridge circuit is in the forward connection state, that is, the voltage value at the other end of the second bridge circuit is equal to the voltage value at one end at this time; when the fifth control switch and the sixth control switch are closed and the seventh control switch and the eighth control switch are open, the second bridge circuit is in the forward bypass state, that is, the voltage value at the other end of the second bridge circuit is 0 at this time; when the sixth control switch and the seventh control switch are closed and the fifth control switch and the eighth control switch are open, the second bridge circuit is in the reverse connection state, that is, the voltage value at the other end of the second bridge circuit is equal to the negative value of the voltage value at one end at this time; when the fifth control switch and the sixth control switch are open and the seventh control switch and the eighth control switch are closed, the second bridge circuit is in the reverse bypass state, that is, the voltage value at the other end of the second bridge circuit is 0 at this time.

[0044] Furthermore, by correspondingly sending control signals to the control terminals of each control switch in the second bridge circuit, the controller can control the voltage value at the other end of the second bridge circuit, so as to generate a required voltage change waveform at one end of the charge and discharge circuit of the capacitive energy storage unit.

[0045] Exemplarily, if a target power supply circuit is selected to be connected to the capacitive energy storage unit, when the third control switch Q3 is closed and the fourth control switch Q4 is open, the voltage value at the other end of the first bridge circuit is the voltage value of the battery of the target power supply circuit. When the second bridge circuit is controlled to be in the forward connection state, the voltage value at one end of the charge and discharge circuit is the voltage value of the battery.

[0046] That is to say, in this application, by setting multiple power supply circuits, the function of improving the electric energy capacity of the energy storage system is achieved. And when a battery of any power supply circuit fails, the power supply circuit can be controlled to be bypassed, and other power supply circuits can be controlled to be normally applied. At the same time, the problem of insufficient system power caused by too many faulty batteries in the system will not occur, and the normal use of the energy storage unit will not be affected. Because multiple power supply circuits are set, the battery of a certain power supply circuit can also be kept in a standby state all the time to centrally calibrate the SOC of the battery.

[0047] Moreover, multiple power supply circuits can also be controlled to be put into use together, increasing the service time of the energy storage module, and can play a role in shunting to prevent irreversible damage to a single battery caused by excessive bus current; or, multiple power supply circuits can be controlled to be used alternately to prevent problems such as overheating and accelerated attenuation of a certain battery caused by long-term use.

[0048] Based on the same application concept, an energy storage system corresponding to the above-described expanded energy storage unit is further provided in the embodiments of the present application. Since the principle of solving problems by the energy storage system in the embodiments of the present application is similar to that of the expanded energy storage unit in the above embodiments of the present application, the implementation of the device can refer to the implementation, and the repeated parts will not be described again.

[0049] The energy storage system includes a bridge arm, and the bridge arm includes a plurality of expanded energy storage units connected in series as described in the above embodiments. The bridge arm is a single-phase bridge arm or a three-phase bridge arm.

[0050] That is to say, the energy storage system includes a single-phase bridge arm, and the single-phase bridge arm includes a plurality of expanded energy storage units connected in series. Thus, the single-phase bridge arm can output single-phase electricity or receive single-phase electrical energy; or, the energy storage system includes a three-phase bridge arm, and each single-phase bridge arm includes a plurality of expanded energy storage units connected in series. Thus, the three-phase bridge arm can output three-phase electricity or receive three-phase electrical energy.

[0051] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0052] It should also be noted that unless otherwise clearly specified and limited, the terms "set", "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0053] The above are only the embodiments of the present application and are not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An expanded energy storage unit, characterized in that: The capacity expansion energy storage unit comprises: A charge and discharge circuit, one end of which is connected to an external device; A plurality of power supply circuits, the plurality of power supply circuits are connected in parallel to the other end of the charging and discharging circuit, and the control end of each power supply circuit is used to receive a control signal for changing the on-off state of the power supply circuit; Wherein, each power supply circuit comprises a first control switch and a battery connected in series, and a control end of the first control switch serves as a control end of the power supply circuit; Each power supply circuit also includes a second control switch and a diode, wherein a first connection end of the second control switch is connected to a first connection end of the first control switch, a second connection end of the second control switch is connected to one end of the diode, and the other end of the diode is connected to the second connection end of the first control switch.

2. The capacity expansion energy storage unit according to claim 1, characterized in that: The capacity expansion energy storage unit further includes a filter circuit, which is arranged between the other end of the charge and discharge circuit and the plurality of power supply circuits.

3. The capacity expansion energy storage unit according to claim 2, characterized in that: The charging and discharging circuit includes a first bridge circuit and a second bridge circuit. One end of the first bridge circuit serves as the other end of the charge and discharge circuit, the other end of the first bridge circuit is connected to one end of the second bridge circuit, and the other end of the second bridge circuit serves as one end of the charge and discharge circuit.

4. The capacity expansion energy storage unit according to claim 3, characterized in that: The first bridge circuit includes a third control switch and a fourth control switch, One end of the third control switch is connected to one end of the filter circuit, the other end of the third control switch is connected to one end of the fourth control switch, and the other end of the fourth control switch is connected to the other end of the filter circuit.

5. The capacity expansion energy storage unit according to claim 4, characterized in that: The second bridge circuit includes a fifth control switch, a sixth control switch, a seventh control switch and an eighth control switch, One end of the fifth control switch is connected to one end of the sixth control switch, the other end of the fifth control switch is connected to one end of the seventh control switch, the other end of the sixth control switch is connected to one end of the eighth control switch, and the other end of the seventh control switch is connected to the other end of the eighth control switch.

6. The capacity expansion energy storage unit according to claim 5, characterized in that: One end of the fifth control switch is connected to the other end of the third control switch, the other end of the seventh control switch is connected to the other end of the fourth control switch, and the connection between the fifth control switch and the seventh control switch and the connection between the sixth control switch and the eighth control switch serve as the other end of the second bridge circuit.

7. An energy storage system, characterized in that: The energy storage system comprises a bridge arm, and the bridge arm comprises a plurality of capacity expansion energy storage units as described in any one of claims 1 to 6 connected in series.

8. The energy storage system according to claim 7, characterized in that: The bridge arm is a single-phase bridge arm or a three-phase bridge arm.

Images