A conversion power supply and autonomous power compensation method of an energy storage system

Abstract

This application provides a power conversion system and an autonomous power replenishment method for an energy storage system. In the power conversion system, the input terminal of the power supply module is connected to an external power source through the power supply interface of the power conversion system; the output terminal of the power supply module is connected to the second side of a first DC / DC converter through an energy storage element, thereby enabling the energy received at its input terminal to be output to the first DC / DC converter through the energy storage element; moreover, the first side of the first DC / DC converter is connected to each battery cluster of the energy storage system through the DC interface of the power conversion system, thereby enabling the power supply controller to receive energy from the energy storage element (i.e., the energy on its second side) and transmit it to its first side when the voltage of a battery cluster is lower than a preset threshold, thereby realizing the power replenishment function for at least one battery cluster and preventing battery over-discharge failure.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a power conversion power supply and autonomous power replenishment method for an energy storage system. Background Technology

[0002] With the large-scale installation and application of energy storage systems, the problem of battery over-discharge is becoming increasingly apparent. For example, when a battery subsystem malfunctions, such as a failure of main circuit components like the PCS (Power Conversion System), and maintenance is not timely, the battery system will be unable to charge and discharge normally through the PCS for an extended period. Furthermore, the battery's self-discharge rate significantly increases the risk of over-discharge failure. Current technology only allows for recharging the battery using a separate charging tool after over-discharge failure is detected.

[0003] Therefore, there is an urgent need for a solution to prevent battery over-discharge failure in energy storage systems. Summary of the Invention

[0004] In view of this, this application provides a power conversion method and an autonomous power replenishment method for an energy storage system to prevent battery over-discharge failure.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] The first aspect of this application provides a power conversion system for an energy storage system, comprising: a power conversion controller, an energy storage element, a first DC / DC converter, and a power supply module; wherein,

[0007] On the first side of the first DC / DC converter, each battery cluster in the energy storage system is connected through the DC interface of the conversion power supply;

[0008] The second side of the first DC / DC converter and the output terminal of the power supply module are both connected to the energy storage element;

[0009] The input terminal of the power supply module is connected to an external power source through the power supply interface of the conversion power source;

[0010] The power conversion controller is used to control the power supply module to output electrical energy to the energy storage element when the voltage of the battery cluster is lower than a preset threshold, and to control the first DC / DC converter to transmit the electrical energy received on its second side to its first side, so as to replenish the power of at least one of the battery clusters.

[0011] Optionally, it may also include: a first switching unit;

[0012] Each port on the first side of the first switching unit is connected to a corresponding interface in the DC interface.

[0013] The second side of the first switching unit is connected to the first side of the first DC / DC converter;

[0014] The first switching unit is controlled by the conversion power controller to enable the selection between any port on its first side and its second side.

[0015] Optionally, the power conversion controller is further configured to: control the first DC / DC converter to transmit the electrical energy received on its second side to its first side, and transmit it to the corresponding interface in the DC interface through the first switching unit, with the goal of achieving balance among the battery clusters.

[0016] Optionally, one of the DC interfaces is used to connect to the DC bus of the energy storage system for external connection.

[0017] Optionally, the power conversion controller is further configured to: with the goal of establishing a soft-start voltage on the DC bus, control the first DC / DC converter to transmit the electrical energy received on its second side to its first side, and transmit it through the first switching unit to the interface in the DC interface connected to the DC bus.

[0018] Optionally, it may also include: a second DC / DC converter;

[0019] The first side of the second DC / DC converter is connected to the energy storage element;

[0020] On the second side of the second DC / DC converter, each DC load in the energy storage system is connected through the load interface of the conversion power supply;

[0021] The power conversion controller is also used to: control the power supply module to output electrical energy to the energy storage element, and control the second DC / DC converter to supply power to each of the DC loads.

[0022] Optionally, the first DC / DC converter is a bidirectional DC / DC converter;

[0023] The power conversion controller is further configured to: control the first DC / DC converter to transmit the electrical energy received on its first side to its second side, and replace the power supply module to output electrical energy to the energy storage element, so that the second DC / DC converter supplies power to each of the DC loads.

[0024] Optionally, the topology in the first DC / DC converter is any one of the following: bidirectional BUCK-BOOST topology, bidirectional BOOST-BUCK topology, bidirectional Cuk topology, and bidirectional Sepic-Zeta topology.

[0025] Alternatively, the topology in the first DC / DC converter is a phase-shifted full-bridge topology;

[0026] Alternatively, the topology in the first DC / DC converter may be any of the following: a full-bridge isolated voltage source topology, an isolated voltage source topology with a primary-side half-bridge circuit and a secondary-side push-pull circuit, a full-bridge isolated current source topology, and an isolated current source topology with a primary-side push-pull circuit and a secondary-side hybrid bridge circuit.

[0027] Optionally, the second DC / DC converter is either a unidirectional buck converter or an isolated buck converter.

[0028] Optionally, each of the DC loads includes at least one of the following: the power conversion controller, the security controller in the energy storage system, the temperature control unit controller, the battery system controller, the cluster management unit controller, and the battery over-discharge alarm buzzer.

[0029] Optionally, the power supply module is an AC / DC converter;

[0030] The external power source includes: mains power and at least one AC generator.

[0031] Optionally, the AC / DC converter is an uncontrolled rectifier converter.

[0032] Optionally, it may also include: a second switching unit;

[0033] Each port on the first side of the second switching unit is connected to a corresponding interface in the power supply interface;

[0034] The second side of the second switching unit is connected to the input terminal of the power supply module;

[0035] The second switching unit is controlled by the conversion power controller to enable the selection between any port on its first side and its second side.

[0036] Optionally, the energy storage element is any one of the following: an electrolytic capacitor, a metal film capacitor, a lithium capacitor, and a lead-acid battery.

[0037] A second aspect of this application provides an autonomous power replenishment method for an energy storage system, applied to a power conversion controller in the power conversion power supply of an energy storage system as described in any of the first aspects above; the autonomous power replenishment method includes:

[0038] Determine whether there are battery clusters in the energy storage system whose voltage is lower than a preset threshold;

[0039] If the voltage of any of the battery clusters is lower than the preset threshold, the power supply module in the conversion power supply is controlled to operate, and the first DC / DC converter transmits the electrical energy received on its second side to its first side, and transmits it to at least one of the battery clusters through the DC interface.

[0040] Optionally, when the power supply includes a first switching unit, after the first DC / DC converter transfers the electrical energy received on its second side to its first side, it further includes:

[0041] The first switching unit is controlled to operate so as to transfer the corresponding electrical energy to the battery cluster whose voltage is lower than the preset threshold.

[0042] Optional, also includes:

[0043] Determine whether the battery clusters are balanced;

[0044] If there are unbalanced battery clusters, the power supply module is controlled to operate, and the first DC / DC converter transmits the electrical energy received on its second side to its first side, and then transmits it to the corresponding battery cluster through the first switching unit.

[0045] Optional, also includes:

[0046] Determine whether a soft-start voltage needs to be established for the DC bus that enables external connection to the energy storage system;

[0047] If necessary, the power supply module is controlled to operate, and the first DC / DC converter transmits the electrical energy received on its second side to its first side, and then transmits it to the DC bus through the first switching unit.

[0048] Optionally, when the external power source connected to the conversion power supply includes mains power and at least one AC generator, and the conversion power supply includes a second switching unit, controlling the power supply module in the conversion power supply to operate includes:

[0049] Determine if the mains power supply is normal;

[0050] If the mains power supply is normal, the power supply module is controlled to receive the mains power supply through the second switching unit and output electrical energy to the energy storage element in the conversion power supply.

[0051] If the mains power supply is abnormal, determine whether at least one of the aforementioned AC generators is supplying power normally;

[0052] If at least one of the AC generators is supplying power normally, the power supply module is controlled to receive the power supply from the corresponding AC generator through the second switching unit and output it to the energy storage element.

[0053] If the AC generator is not functioning properly and is supplying power, an alarm buzzer will be triggered.

[0054] Optionally, when the external power source connected to the conversion power supply includes mains power and at least one AC generator, and the conversion power supply includes a first switching unit, a second switching unit, and a second DC / DC converter, after determining whether there is a battery cluster in the energy storage system with a voltage lower than a preset threshold, the following steps are also included:

[0055] If no battery cluster has a voltage lower than a preset threshold, then determine whether the mains power supply is normal.

[0056] If the mains power supply is normal, the power supply module is controlled to receive the mains power supply through the second switching unit, convert and output electrical energy to the energy storage element in the conversion power supply, and the second DC / DC converter is controlled to transmit the electrical energy received on its first side to its second side.

[0057] If the mains power supply is abnormal, the first DC / DC converter is controlled to receive power from any of the battery clusters in turn through the first switching unit or to receive power from the DC bus that connects the energy storage system to the outside, and output the converted power to the energy storage element. The second DC / DC converter is then controlled to transmit the power received on its first side to its second side.

[0058] The energy storage system provided in this application has a power supply module whose input terminal is connected to an external power source through the power supply interface of the power supply module. The output terminal of the power supply module is connected to the second side of a first DC / DC converter through an energy storage element, thereby enabling the power received at the input terminal of the power supply module to be output to the first DC / DC converter through the energy storage element. Furthermore, the first side of the first DC / DC converter is connected to each battery cluster of the energy storage system through the DC interface of the power supply module. Thus, under the control of the power supply controller, when the voltage of a battery cluster is lower than a preset threshold, the power supply module receives the power from the energy storage element, i.e., the power from the second side of the first DC / DC converter, and transmits it to the first side of the first DC / DC converter to achieve the function of replenishing power for at least one battery cluster and preventing battery over-discharge failure. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0060] Figure 1 This is a schematic diagram of the energy storage system provided in the embodiments of this application;

[0061] Figure 2a A schematic diagram of the conversion power supply of the energy storage system provided in the embodiments of this application;

[0062] Figure 2b Another schematic diagram of the conversion power supply of the energy storage system provided in the embodiments of this application;

[0063] Figure 3a , Figure 3b , Figure 3c , Figure 3d , Figure 4 , Figure 5 , Figure 6a , Figure 6b , Figure 6c , Figure 6d These are schematic diagrams illustrating eight specific structures of the first DC / DC converter provided in the embodiments of this application.

[0064] Figure 7 A flowchart illustrating the autonomous power replenishment method for an energy storage system provided in this application embodiment;

[0065] Figure 8 A partial flowchart of the autonomous power replenishment method for an energy storage system provided in an embodiment of this application;

[0066] Figure 9 Another flowchart of the autonomous power replenishment method for the energy storage system provided in the embodiments of this application. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0069] This application provides a power conversion system for an energy storage system to prevent battery over-discharge failure.

[0070] This energy storage system, such as Figure 1 As shown, it includes: BSC (Battery system controller), at least one battery cluster (such as...) Figure 1 The battery clusters 1 to n shown herein and their cluster-level management units (such as...) Figure 1 The diagram shows cluster-level management units 1 to 2 (n), and a power conversion unit 10; each battery cluster is connected in parallel to the DC bus DC_BUS through its corresponding cluster-level management unit, and is connected to the external network through the DC bus DC_BUS, for example, to the PCS (i.e., PCS). Figure 1 The inverter in the circuit is connected to the DC bus and downstream equipment such as the power grid or AC loads via the PCS. Each cluster-level management unit is controlled by the BSC, which is communicatively connected to the conversion power supply 10.

[0071] See Figure 2a The energy storage system's conversion power supply 10 includes: a conversion power supply controller 100, an energy storage element 102, a first DC / DC converter 101, and a power supply module 103; wherein:

[0072] On the first side of the first DC / DC converter 101, the battery clusters in the energy storage system are connected through the DC interface of the power supply. In practical applications, the DC interface may include multiple interfaces, each of which is connected to at least one corresponding battery cluster. There may also be an interface for connecting to the aforementioned DC bus. The voltage of each interface may be 1500V.

[0073] In practical applications, a connection can also be provided between the first side of the first DC / DC converter 101 and the DC interface. Figure 2b As shown: a first switching unit 104; each port on the first side of the first switching unit 104 is connected to a corresponding interface in the DC interface; the second side of the first switching unit 104 is connected to the first side of the first DC / DC converter 101; the first switching unit 104 is controlled by the conversion power controller 100 to enable selection between any port on its first side and its second side, thereby enabling selection of multiple DC inputs and constructing an exclusive interlock, that is, ensuring that two DC inputs will not be connected at the same time.

[0074] The second side of the first DC / DC converter 101 and the output terminal of the power supply module 103 are both connected to the energy storage element 102. In practical applications, the energy storage element 102 can be any single device among electrolytic capacitor, metal film capacitor, lithium capacitor and lead-acid battery, or it can be a capacitor battery implemented by any type of capacitor, but it is not limited to these. It depends on the specific application environment and is within the protection scope of this application.

[0075] The input terminal of the power supply module 103 is connected to an external power source through the power supply interface of the conversion power supply. The power supply module 103 can be a DC / DC converter or an AC / DC converter. When it is an AC / DC converter, the external power source can include at least one of mains power and at least one AC generator. The AC generator can be a diesel engine, but is not limited to this, depending on the specific application environment, and is within the protection scope of this application. Specifically, the external power source can provide 220V AC power. Considering structural cost and control complexity, the AC / DC converter is preferably an uncontrolled rectifier converter, but is not limited to this. It can also be a rectifier implemented by a controllable semiconductor, depending on the specific application environment, and is within the protection scope of this application.

[0076] In practical applications, a connection can also be provided between the input terminal of the power supply module 103 and the power supply interface. Figure 2b As shown: a second switching unit 105; each port on the first side of the second switching unit 105 is connected to a corresponding interface in the power supply interface; the second side of the second switching unit 105 is connected to the input terminal of the power supply module 103; the second switching unit 105 is controlled by the conversion power controller 100, realizing the selection between any port on its first side and its second side, thereby realizing the selection of multiple AC access, and can construct an exclusive interlock, that is, ensuring that two AC accesses will not be connected at the same time.

[0077] The specific working principle is as follows:

[0078] When the voltage of a battery cluster falls below a preset threshold, the power conversion controller 100 controls the power supply module 103 to convert the AC power received at its input and output it to the energy storage element 102. The first DC / DC converter 101 will also receive the electrical energy from the energy storage element 102 (i.e., the electrical energy on its second side) according to the control of the power conversion controller 100 and transmit it to its first side to achieve the function of replenishing power for at least one battery cluster and prevent battery over-discharge failure.

[0079] It is worth noting that when the first side of the first DC / DC converter 101 is directly connected to the DC interface of the power supply 10 (e.g., Figure 2a As shown), the power supply 10 will simultaneously charge each battery cluster; when the first side of the first DC / DC converter 101 is connected to the DC interface of the power supply 10 through the first switching unit 105 (as shown) Figure 2b As shown, the power conversion power supply 10 can accurately replenish any depleted battery cluster under the control of the power conversion power supply controller 100, or it can replenish multiple depleted battery clusters in turn; depending on the specific application environment, all of which are within the protection scope of this application.

[0080] In practical applications, the preset threshold can be the voltage value that triggers the over-discharge warning, or it can be higher than that voltage value, depending on the specific application environment, and all of them are within the protection scope of this application.

[0081] The energy storage system conversion power supply 10 provided in this embodiment, when the battery system is undervoltage and the main circuit cannot charge or discharge due to a partial fault, constructs the aforementioned charging circuit. Power is supplied by an external power source such as station mains power or a diesel generator, and the battery clusters are charged via the conversion power supply 10 to prevent battery failure due to over-discharge. Furthermore, based on the above principle, the conversion power supply 10 can actively replenish the battery clusters and maintain a self-replenishing channel that prevents the battery clusters from over-discharging.

[0082] Based on the previous embodiment, when the conversion power supply 10 includes a first switching unit 104, preferably:

[0083] The power conversion controller 100 in the energy storage system can also be further used to: control the first DC / DC converter 101 to transmit the electrical energy received on its second side to its first side with the goal of achieving balance between the battery clusters, and transmit it to the corresponding interface in the DC interface through the first switching unit 104.

[0084] At this point, the power conversion 10 can further achieve the equalization function for each battery cluster.

[0085] And / or, when there is one interface in the DC interface of the power conversion power supply 10 for connecting to the DC bus, the power conversion power supply controller 100 can be further used to: with the goal of establishing a slow-start voltage on the DC bus, control the first DC / DC converter 101 to transmit the electrical energy received on its second side to its first side, and transmit it to the interface in the DC interface connected to the DC bus through the first switching unit 104.

[0086] At this point, the converter power supply 10 can further realize the function of slow-start voltage establishment on the DC bus.

[0087] In practical applications, the power conversion power supply 10 can simultaneously possess the above-mentioned power replenishment function, equalization function, and slow-start voltage establishment function, or it can be selected according to actual needs and its specific application environment, all of which are within the protection scope of this application.

[0088] Based on the above embodiments, see Figure 2b The power supply 10 may further include a second DC / DC converter 106, in which case:

[0089] The first side of the second DC / DC converter 106 is connected to the energy storage element 102.

[0090] On the second side of the second DC / DC converter 106, various DC loads within the energy storage system are connected via the load interface of the power supply 10. In practical applications, this load interface may also include multiple interfaces, each connected to a corresponding DC load. These DC loads can be various controllers within the energy storage system, specifically including at least one of the following: the power supply controller 100, a security controller, a temperature control unit controller, a BSC, cluster-level management unit controllers, and a battery over-discharge alarm buzzer, with a power supply voltage primarily of 24VDC.

[0091] The power conversion controller 100 can control the power supply module 103 to output electrical energy to the energy storage element 102, and control the second DC / DC converter 106 to receive the DC power from the energy storage element 102, convert it, and then supply power to each DC load, thereby realizing the power supply to each DC load. At this time, the power conversion controller 10 can have the function of auxiliary power supply.

[0092] In practical applications, the second DC / DC converter 106 can be a unidirectional buck converter or an isolated buck converter, but it is not limited to these. It depends on the specific application environment and is within the protection scope of this application.

[0093] More preferably, the first DC / DC converter 101 is a bidirectional DC / DC converter that can realize bidirectional buck-boost conversion. Under the control of the power conversion controller 100, it can not only realize the function of replenishing the corresponding battery cluster to prevent battery over-discharge failure, but also convert the electrical energy of the corresponding battery cluster received by its first side through the DC interface and output it to the energy storage element 102.

[0094] That is, the conversion power supply 10 can draw power from an external power source connected to its power supply interface, or it can draw power from the power transmission branches of each battery cluster (such as...). Figure 1 The DC_BUS 1 to DC_BUS n shown or the DC bus DC_BUS, for example, take power from the power transmission branches of each battery cluster in turn, and then supply power to each DC load inside the energy storage system.

[0095] In practical applications, when the mains power supply is normal, the power conversion controller 100 can control the second DC / DC converter 106 to receive power from the mains power supply through the power supply module 103; when the mains power supply is abnormal, the second DC / DC converter 106 can receive power from the DC interface through the first DC / DC converter 101, and then replace the power supply module 106 to output power to the energy storage element 102, so that the second DC / DC converter 106 can continue to supply power to each DC load, that is, it can replace the UPS (Uninterruptible Power Supply) to achieve uninterrupted self-power supply to each DC load.

[0096] The energy storage system conversion power supply 10 provided in this embodiment designs the first DC / DC converter 101 connected to the battery cluster or PCS DC bus as a bidirectional buck-boost converter. During normal operation, it draws power from the mains or battery side, and after power conversion, outputs a 24VDC power supply for use by each core controller; it can realize AC and DC dual input power supply for the energy storage system auxiliary power supply. Moreover, through the above-mentioned bidirectional DC / DC conversion design, combined with corresponding software control, the conversion power supply 10 can simultaneously realize the auxiliary power supply function of battery DC self-powered supply and the function of effectively preventing battery over-discharge failure, resulting in low system cost.

[0097] In practical applications, the internal program of the power conversion controller 100 can be configured so that the first DC / DC converter 101 can either draw power from the battery cluster or the PCS DC bus, step down the voltage to charge the energy storage element 102, or have the energy storage element 102 charge the battery cluster, thereby achieving at least one of the following functions: power replenishment, active balancing between battery clusters, auxiliary power supply, and replacing the conventional soft-start resistor as a means of establishing the soft-start voltage at the PCS output terminal; the specific application environment can be determined as needed, and all of these are within the scope of protection of this application.

[0098] Furthermore, the DC power output by the power supply module 103 can be transmitted to any one DC / DC converter or simultaneously to two DC / DC converters through the energy storage element 102, depending on the specific actual needs, all of which are within the protection scope of this application. In this way, for over-discharge caused by equipment maintenance, local power grid failure, or providing auxiliary power for a long time during standby, the above principle can also realize the corresponding battery cluster's recharging function to prevent battery over-discharge failure. That is, the conversion power supply of the energy storage system provided in this embodiment can be applied to situations where the battery cluster triggers an over-discharge warning due to various reasons.

[0099] In practical applications, the first DC / DC converter 101 can have a variety of selectable topologies. The simplest is any of the following: bidirectional BUCK-BOOST topology (e.g., Figure 3aAs shown), bidirectional BOOST-BUCK topology (such as...) Figure 3b As shown), bidirectional Cuk topology (such as...) Figure 3c (as shown) and bidirectional Sepic-Zeta topology (such as Figure 3d (as shown in the image).

[0100] In practical applications, considering power requirements, such as a large number of DC loads, the topology in the first DC / DC converter 101 can also be any of the above-mentioned topologies, for example... Figure 4 The three-phase interleaved parallel DC-DC converter topology shown is a triple Figure 3a The bidirectional BUCK-BOOST topology shown is illustrated; the dual forms of this bidirectional BUCK-BOOST topology, as well as the dual and multiple forms of several other topologies, are not shown one by one, but are all within the protection scope of this application.

[0101] Alternatively, in a slightly more complex scenario, the topology in the first DC / DC converter 101 could also be... Figure 5 The phase-shifted full-bridge topology shown; or, for safety considerations, the topology in the first DC / DC converter 101 can also be an isolated conversion structure, specifically any of the following: a full-bridge isolated voltage source topology (such as... Figure 6a As shown in the diagram), the isolated voltage source topology of the primary-side half-bridge circuit and the secondary-side push-pull circuit (such as...) Figure 6b As shown), full-bridge isolated current source topology (such as...) Figure 6c As shown in the figure), and the isolated current source topology of the primary-side push-pull circuit and the secondary-side hybrid bridge circuit (as ...). Figure 6d (as shown in the image).

[0102] The switching transistors in the above-mentioned topologies are controlled by the power conversion controller 100, and the corresponding control signals can be PWM (pulse width modulation) signals. The control process will not be described in detail.

[0103] The above are some topological examples of the first DC / DC converter 101, and are not limited to them; as long as the first DC / DC converter 101 can realize bidirectional buck-boost conversion, it is within the protection scope of this application.

[0104] Another embodiment of this application provides an autonomous power replenishment method for an energy storage system, which is applied to the power conversion controller in the power conversion power supply of the energy storage system as described in any of the above embodiments; the specific structure and working principle of the energy storage system and its power conversion power supply can be found in the above embodiments, and will not be repeated here.

[0105] See Figure 7 The autonomous power replenishment method includes:

[0106] S101. Determine whether there are battery clusters in the energy storage system whose voltage is lower than a preset threshold.

[0107] In practical applications, the preset threshold can be the voltage value that triggers the over-discharge warning, or it can be higher than that voltage value, depending on the specific application environment, and all of them are within the protection scope of this application.

[0108] If the voltage of a battery cluster is lower than a preset threshold, then step S102 is executed.

[0109] S102, Control the operation of the power supply module in the conversion power supply, the first DC / DC converter transmits the electrical energy received on its second side to its first side, and transmits it to at least one battery cluster through the DC interface.

[0110] When the power conversion power supply includes a first switching unit, after the first DC / DC converter transmits the electrical energy received on its second side to its first side, it may further include: controlling the first switching unit to operate so as to transmit the corresponding electrical energy to the battery cluster with a voltage lower than a preset threshold; at this time, through the coordinated work of the power supply module, the first DC / DC converter and the first switching unit, it is possible to accurately replenish or alternately replenish the over-discharged battery cluster.

[0111] Specifically, when the external power source connected to the power conversion power supply includes mains power and at least one AC generator, and the power conversion power supply includes a second switching unit, step S102, controlling the operation of the power supply module in the power conversion power supply, may include... Figure 8 As shown:

[0112] S201. Determine if the mains power supply is normal.

[0113] If the mains power supply is normal, proceed to step S202. If the mains power supply is abnormal, proceed to step S203.

[0114] S202, The control power supply module receives mains power through the second switching unit and outputs electrical energy to the energy storage element in the conversion power supply.

[0115] At this time, the power converter can use the mains power supply to reverse charge the battery cluster.

[0116] S203. Determine if at least one AC generator is supplying power normally.

[0117] If at least one AC generator is supplying power normally, proceed to step S204. If no AC generator is supplying power normally, proceed to step S205.

[0118] S204. The control power supply module receives the electrical energy supply from the corresponding AC generator through the second switching unit and outputs it to the energy storage element.

[0119] At this point, the power source can use the electrical energy supplied by the alternator to reverse charge the battery cluster.

[0120] S205, Trigger alarm buzzer.

[0121] In other words, in practical applications, it is preferable to use mains power to replenish over-discharged battery clusters. When the mains power is abnormal, an AC generator can be used as a substitute for replenishment. When both the mains power and the AC generator are abnormal, the alarm buzzer can be triggered to notify the operator in time for maintenance, which can also avoid damage to the corresponding equipment of the inverter.

[0122] Furthermore, when the external power source connected to the power conversion power supply includes mains power and at least one AC generator, and the power conversion power supply includes a first switching unit, a second switching unit, and a second DC / DC converter, after step S101, the autonomous power replenishment method may further include... Figure 9 (in) Figure 7 As shown in the example (based on which):

[0123] If no battery cluster has a voltage lower than the preset threshold, then proceed to step S103.

[0124] S103. Determine if the mains power supply is normal.

[0125] If the mains power supply is normal, proceed to step S104. If the mains power supply is abnormal, proceed to step S105.

[0126] S104. The control power supply module receives the mains power supply through the second switching unit, converts it, and outputs electrical energy to the energy storage element in the conversion power supply. It also controls the second DC / DC converter to transmit the electrical energy received on its first side to its second side.

[0127] S105. Control the first DC / DC converter to receive electrical energy from any battery cluster or the DC bus in turn through the first switching unit, convert it and output it to the energy storage element, and control the second DC / DC converter to transmit the electrical energy received on its first side to its second side.

[0128] In other words, in practical applications, it is preferable to use mains power to supply power to each DC load. In the event of a mains power failure, the battery pack self-powered power supply can be used as a substitute to achieve this auxiliary power supply function.

[0129] In addition, in order to achieve the autonomous balancing control described in the above embodiments, the autonomous power replenishment method may further include, at any time: determining whether the battery clusters are balanced; if there are unbalanced battery clusters, controlling the power supply module to work, the first DC / DC converter to transmit the electrical energy received on its second side to its first side, and then to the corresponding battery cluster through the first switching unit.

[0130] To implement the aforementioned slow-start function, the autonomous power replenishment method may, at any given time, further include: determining whether a slow-start voltage needs to be established for the DC bus that provides external connection to the energy storage system; if so, controlling the power supply module to operate, with the first DC / DC converter transmitting the electrical energy received on its second side to its first side, and then transmitting it to the DC bus through the first switching unit.

[0131] The autonomous power replenishment method provided in this embodiment can not only charge the battery clusters from the energy storage elements through the first DC / DC converter with bidirectional buck-boost conversion to achieve the corresponding power replenishment function, but also draw power from the battery clusters or the PCS DC bus, step down the voltage and charge the energy storage elements to achieve uninterrupted self-power supply for each DC load; in addition, it can maintain active balance control between each battery cluster and establish a soft-start voltage at the PCS output terminal; that is, it can achieve multiple functions, and has low cost and simple control logic.

[0132] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0133] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0134] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A conversion power source of an energy storage system, characterized by, The energy storage system includes at least one battery cluster and a cluster-level management unit corresponding to the at least one battery cluster. Each battery cluster is connected in parallel to a DC bus through its corresponding cluster-level management unit. The DC bus is used to connect to a first side of an energy storage converter outside the energy storage system, and the second side of the energy storage converter is connected to the power grid or an AC load. The conversion power supply includes: a first switching unit, a conversion power supply controller, an energy storage element, a first DC / DC converter, a second DC / DC converter, and a power supply module. The first DC / DC converter is a bidirectional DC / DC converter. Each port on the first side of the first switching unit is connected to each battery cluster in the energy storage system through the DC interface of the conversion power supply, and the second side of the first switching unit is connected to the first side of the first DC / DC converter. The second side of the first DC / DC converter and the output terminal of the power supply module are both connected to the energy storage element; The first side of the second DC / DC converter is connected to the energy storage element, and the second side of the second DC / DC converter is connected to each DC load in the energy storage system through the load interface of the conversion power supply. The input terminal of the power supply module is connected to an external power source through the power supply interface of the conversion power source; The power conversion controller is configured to, when the voltage of at least one battery cluster in the energy storage system is lower than a preset threshold, control the power supply module to output electrical energy to the energy storage element, control the first DC / DC converter to transmit the electrical energy received from the energy storage element on the second side of the first DC / DC converter to the first side of the first DC / DC converter, and control the corresponding port on the first side of the first switching unit to connect with the second side of the first switching unit to replenish the power of at least one battery cluster whose voltage is lower than the preset threshold, wherein the battery cluster whose voltage is lower than the preset threshold is at risk of over-discharge failure; The conversion power controller is also used to control the power supply module to receive the external power supply, convert and output electrical energy to the energy storage element in the conversion power supply if there is no battery cluster with voltage lower than a preset threshold in the energy storage system and the external power supply is normal, and to control the second DC / DC converter to convert the electrical energy of the energy storage element and transmit it to each DC load in the energy storage system. The power conversion controller is further configured to, if there are no battery clusters in the energy storage system with voltages lower than a preset threshold and the external power supply is abnormal, control the first DC / DC converter to receive power from any of the battery clusters in turn through the first switching unit or to receive power from the DC bus connected to the external energy storage system, convert the power and output it to the energy storage element, and control the second DC / DC converter to convert the power received from the energy storage element on the first side to supply power to each DC load.

2. The conversion power source of an energy storage system according to claim 1, characterized by, The DC interface also includes an interface for connecting to the DC bus in the energy storage system for connecting to external systems.

3. The conversion power source of an energy storage system according to claim 2, characterized by, The power conversion controller is further configured to: control the first DC / DC converter to transmit the electrical energy received on the second side of the first DC / DC converter to the first side of the first DC / DC converter, and transmit it to the interface in the DC interface connected to the DC bus through the first switching unit.

4. The energy storage system conversion power supply of any of claims 1-3, wherein, The topology in the first DC / DC converter is any one of the following: bidirectional BUCK-BOOST topology, bidirectional BOOST-BUCK topology, bidirectional Cuk topology, and bidirectional Sepic-Zeta topology; Alternatively, the topology in the first DC / DC converter is a phase-shifted full-bridge topology; Alternatively, the topology in the first DC / DC converter may be any of the following: a full-bridge isolated voltage source topology, an isolated voltage source topology with a primary-side half-bridge circuit and a secondary-side push-pull circuit, a full-bridge isolated current source topology, and an isolated current source topology with a primary-side push-pull circuit and a secondary-side hybrid bridge circuit.

5. The energy storage system of any one of claims 1-3, wherein the energy storage system is a power conversion system. The second DC / DC converter is either a unidirectional buck converter or an isolated buck converter.

6. The energy conversion system of any of claims 1-3, wherein, Each DC load includes at least one of the following: the power conversion controller, the security controller in the energy storage system, the temperature control unit controller, the battery system controller, the cluster-level management unit controller, and the battery over-discharge alarm buzzer.

7. The energy conversion system of any one of claims 1 to 3, wherein the energy storage system comprises a plurality of energy storage units, each energy storage unit comprising a plurality of energy storage cells, and wherein the energy storage units are connected in series. The power supply module is an AC / DC converter; The external power source includes: mains power and at least one AC generator.

8. The power conversion system of the energy storage system according to claim 7, characterized in that, The AC / DC converter is an uncontrolled rectifier converter.

9. The power conversion system of the energy storage system according to any one of claims 1 to 3, characterized in that, Also includes: Second switching unit; Each port on the first side of the second switching unit is connected to a corresponding interface in the power supply interface; The second side of the second switching unit is connected to the input terminal of the power supply module; The second switching unit is controlled by the conversion power controller, which controls the selection between any port on the first side of the second switching unit and the second side of the second switching unit.

10. The power conversion system of the energy storage system according to any one of claims 1 to 3, characterized in that, The energy storage element is any one of the following: electrolytic capacitor, metal film capacitor, lithium capacitor, and lead-acid battery.

11. A method for autonomous power replenishment of an energy storage system, characterized in that, A power conversion controller applied in the power conversion power supply of an energy storage system as described in any one of claims 1 to 10; the autonomous power replenishment method includes: Determine whether there are battery clusters in the energy storage system whose voltage is lower than a preset threshold; If the voltage of the battery cluster is lower than the preset threshold, the power supply module in the conversion power supply is controlled to work. The first DC / DC converter transmits the electrical energy received on the second side of the first DC / DC converter to the first side of the first DC / DC converter, and controls the corresponding port on the first side of the first switching unit to connect with the second side of the first switching unit, so as to transmit the electrical energy on the first side of the first DC / DC converter to the battery cluster whose voltage is lower than the preset threshold. If there are no battery clusters with voltages below the preset threshold, then determine whether the external power supply is normal. If the external power supply is normal, the power supply module is controlled to receive the external power supply, convert it and output electrical energy to the energy storage element in the conversion power supply, and the second DC / DC converter is controlled to transmit the electrical energy of the energy storage element to each DC load in the energy storage system. If the external power supply is abnormal, the first DC / DC converter is controlled to receive electrical energy from any of the battery clusters or from the DC bus connected to the external energy storage system through the first switching unit, and output the converted energy to the energy storage element. The second DC / DC converter is also controlled to transmit the electrical energy received on the first side of the second DC / DC converter to the second side of the second DC / DC converter.

12. The autonomous power replenishment method for an energy storage system according to claim 11, characterized in that, Also includes: Determine whether the battery clusters are balanced; If there are unbalanced battery clusters, the power supply module is controlled to operate, and the first DC / DC converter transmits the electrical energy received on the second side of the first DC / DC converter to the first side of the first DC / DC converter, and transmits it to the corresponding battery cluster through the first switching unit.

13. The autonomous power replenishment method for an energy storage system according to claim 11, characterized in that, Also includes: Determine whether a soft-start voltage needs to be established for the DC bus that enables external connection to the energy storage system; If necessary, the power supply module is controlled to operate, and the first DC / DC converter transmits the electrical energy received on the second side of the first DC / DC converter to the first side of the first DC / DC converter, and transmits it to the DC bus through the first switching unit.

14. The autonomous power replenishment method for an energy storage system according to any one of claims 11 to 13, characterized in that, When the external power source connected to the conversion power supply includes mains power and at least one AC generator, and the conversion power supply includes a second switching unit, controlling the power supply module in the conversion power supply to operate includes: Determine if the mains power supply is normal; If the mains power supply is normal, the power supply module is controlled to receive the mains power supply through the second switching unit and output electrical energy to the energy storage element in the conversion power supply. If the mains power supply is abnormal, determine whether at least one of the aforementioned AC generators is supplying power normally; If at least one of the AC generators is supplying power normally, the power supply module is controlled to receive the power supply from the corresponding AC generator through the second switching unit and output it to the energy storage element. If the AC generator is not functioning properly and is supplying power, an alarm buzzer will be triggered.

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