CN113629821A

CN113629821A - Energy storage system and control method thereof

Info

Publication number: CN113629821A
Application number: CN202111026301.8A
Authority: CN
Inventors: 孙维; 陈飞; 李鹏举; 陈晓光
Original assignee: Sungrow Power Supply Co Ltd
Current assignee: Sungrow Power Supply Co Ltd
Priority date: 2021-09-02
Filing date: 2021-09-02
Publication date: 2021-11-09
Anticipated expiration: 2041-09-02
Also published as: CN113629821B

Abstract

The invention provides an energy storage system and a control method thereof.A control unit can control each battery module to switch in or switch out the battery module into or out of a corresponding battery cluster when the battery module meets corresponding preset conditions so as to adjust the currently accessed battery module in the battery cluster in real time, and further enable each battery module to meet the corresponding preset conditions one by one, namely achieve the same state, such as SOC balance; and at the same time, no energy waste is caused. In addition, the energy storage system is provided with at least one buffer circuit, which can absorb the voltage spike caused by switching in or switching out any battery module in the corresponding battery cluster, i.e. absorb the energy impact caused by the voltage sudden change, thereby avoiding the corresponding device from bearing larger voltage/current stress.

Description

Energy storage system and control method thereof

Technical Field

The invention relates to the technical field of power electronics, in particular to an energy storage system and a control method thereof.

Background

A battery cluster in an energy storage system is generally formed by connecting a plurality of battery modules in series; in the same battery cluster, the problem of imbalance of the SOC (state of charge) of each battery module in the use process is inevitable.

In order to solve the problem of the unbalance of the SOC of the battery module, the current common scheme is as follows: the battery module with high energy is passively discharged through the resistor, and further the excessive energy is dissipated in the form of heat, so that the energy of the battery module is kept consistent with that of the battery module with low energy.

But the scheme can dissipate the redundant energy, which causes the waste of energy.

Disclosure of Invention

In view of this, the present invention provides an energy storage system and a control method thereof, so as to avoid energy waste while implementing SOC balance of a battery module.

In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

a first aspect of the invention provides an energy storage system comprising: the device comprises a control unit, at least one battery cluster, at least one buffer circuit and at least one power converter; wherein:

the battery cluster comprises a plurality of battery modules which are connected in series, and two ends of each battery module after being connected in series are used for connecting the direct current bus of the corresponding power converter;

a bus capacitor is arranged between the positive electrode and the negative electrode of the direct current bus;

the control unit controls each battery module to switch in or switch out the corresponding battery cluster when the corresponding preset condition is met;

the buffer circuit is controlled by the control unit and is used for absorbing voltage spikes caused by switching in or switching out any battery module in the corresponding battery cluster.

Optionally, the buffer circuit includes: the controllable switch and the buffer device are connected in parallel;

when the battery module is switched in or out in the corresponding battery cluster, the controllable switch is in an off state;

and when the voltage difference between the voltage of the corresponding battery cluster and the bus capacitor is smaller than a preset difference value, the controllable switch is in a closed state.

Optionally, the buffer device includes: a resistor, or a resistor and an inductor connected in parallel.

Optionally, the buffer circuit is disposed on the dc bus, or the buffer circuit and the bus capacitor are connected in series between the positive electrode and the negative electrode of the dc bus.

Optionally, still include in the battery module: the battery comprises a battery body, a main loop on-off control circuit and a bypass on-off control circuit; wherein:

the battery body is connected with the anode and the cathode of the battery module through the main loop on-off control circuit;

the bypass on-off control circuit is arranged between the positive electrode and the negative electrode of the battery module.

Optionally, the main loop on-off control circuit and the bypass on-off control circuit both include: a two-way one-way switch group; the two-way one-way switch group comprises: a charge switch and a discharge switch; the control unit controls the charging switch in the main loop on-off control circuit to realize charging of the corresponding battery body, controls the discharging switch in the main loop on-off control circuit to realize discharging of the corresponding battery body, controls the charging switch in the bypass on-off control circuit to realize charging bypass of the corresponding battery body, and controls the discharging switch in the main bypass on-off control circuit to realize discharging bypass of the corresponding battery body;

alternatively, the first and second electrodes may be,

the main loop on-off control circuit and the bypass on-off control circuit both comprise: a single-pass bi-directional switch; and the control unit controls the bidirectional switch in the main loop on-off control circuit to realize charging or discharging of the corresponding battery body, and controls the bidirectional switch in the bypass on-off control circuit to realize a charging bypass or a discharging bypass of the corresponding battery body.

Optionally, the charging switch includes: the charging switch tube and the charging diode are reversely connected in series with the body diode in the charging switch tube; the discharge switch includes: the discharge switch tube and a discharge diode are reversely connected in series with a body diode in the discharge switch tube; the charging switch is connected with the discharging switch in an inverse parallel mode;

alternatively, the first and second electrodes may be,

the charging switch comprises a charging switch tube, and the discharging switch comprises a discharging switch tube; the charging switch tube and the discharging switch tube are both provided with body diodes, and the charging switch tube and the discharging switch tube are connected in series in a reverse direction.

Optionally, a switch box is further disposed between each battery cluster and the corresponding power converter, and the switch box includes: a main circuit switch.

Optionally, the control unit is a battery management system BMS, and the BMS includes: a system battery management unit SMU, a battery cluster management unit CMU of each battery cluster and a battery management unit BMU arranged in each battery module;

the SMU, the CMU and the BMU are in communication connection step by step;

the buffer circuit is controlled by the CMU of the corresponding battery cluster;

the CMU is communicatively coupled to the power converter.

Optionally, the power converter is a DCAC converter; alternatively, the first and second electrodes may be,

the power converters are DCDC converters, and each DCDC converter is connected with a power grid and/or a load through a corresponding DCAC converter.

A second aspect of the present invention further provides a control method for an energy storage system, which is applied to a control unit in the energy storage system as described in any of the paragraphs above for the first aspect; the control method comprises the following steps:

s101, judging whether each battery module in the corresponding battery cluster of the energy storage system meets a corresponding preset condition or not;

if any battery module meets the corresponding preset condition, executing the step S102;

s102, controlling the corresponding battery module to switch in or switch out the battery cluster; meanwhile, controlling a corresponding buffer circuit in the energy storage system to absorb a voltage spike caused when the corresponding battery module is switched in or switched out;

s103, judging whether the voltage difference between the battery cluster and the corresponding bus capacitor is within a preset voltage range;

if the voltage difference is within the preset voltage range, executing step S104;

and S104, controlling the buffer circuit to stop absorbing the voltage spike.

Optionally, the preset condition is a cut-out preset condition or a cut-in preset condition; the buffer circuit includes: the controllable switch and the buffer device are connected in parallel; and in main loop on-off control circuit and the bypass on-off control circuit in the battery module, all include: a single-pass bi-directional switch; then:

when the preset condition is the preset condition for switching, step S102 includes: controlling a bidirectional switch in the corresponding main loop on-off control circuit to be turned off, and simultaneously controlling the controllable switch to be turned off; then controlling the conduction of a bidirectional switch in the corresponding bypass on-off control circuit;

when the preset condition is the cut-in preset condition, step S102 includes: controlling a bidirectional switch in the corresponding bypass on-off control circuit to be turned off, and simultaneously controlling the controllable switch to be turned off; and then the bidirectional switch in the corresponding main loop on-off control circuit is controlled to be conducted.

Optionally, the preset condition is a cut-out preset condition or a cut-in preset condition; the buffer circuit includes: the controllable switch and the buffer device are connected in parallel; the main loop on-off control circuit and the bypass on-off control circuit in the battery module respectively comprise two unidirectional switch sets; then:

when the preset condition is the preset condition for switching, step S102 includes: controlling the corresponding bypass on-off control circuit to be switched on and simultaneously controlling the controllable switch to be switched off;

when the preset condition is the cut-in preset condition, step S102 includes: controlling the on-off control circuit of the corresponding main loop to be conducted; and then controlling the corresponding bypass on-off control circuit to be switched off, and simultaneously controlling the controllable switch to be switched off.

Optionally, when the preset condition is the preset switching-out condition, in step S102, after controlling the corresponding bypass on-off control circuit to be turned on and the controllable switch to be turned off at the same time, the method further includes: and controlling the corresponding main loop on-off control circuit to be switched off.

Optionally, the preset cutting condition is any one of the following conditions:

when the battery cluster is charged, the operation parameter of the corresponding battery module reaches a first cut-out preset condition of a preset upper limit value;

when the battery clusters are discharged, the operation parameters of the corresponding battery modules reach a second switching-out preset condition of a preset lower limit value;

when the battery cluster is charged, a third switching-out preset condition corresponding to the battery module when the battery module is abnormal or fails is set;

when the battery clusters are discharged, a fourth switching-out preset condition corresponding to the battery module when the battery module is abnormal or has a fault is adopted;

the preset cut-in condition is any one of the following conditions:

a first cut-in preset condition that the charging bypass state needs to be recovered to the charging state;

a second cut-in preset condition for restoring from the discharge bypass state to the discharge state is required.

Optionally, the main loop on-off control circuit and the bypass on-off control circuit in the battery module all include: the charging switch tube and the discharging switch tube, then:

when the preset condition is the first cut-out preset condition or the third cut-out preset condition, in step S102, controlling the corresponding bypass on-off control circuit to be turned on, and simultaneously controlling the controllable switch to be turned off, includes: controlling the charging switch tube in the corresponding bypass on-off control circuit to be connected and simultaneously controlling the controllable switch to be disconnected;

when the preset condition is the second cut-out preset condition or the fourth cut-out preset condition, in step S102, controlling the corresponding bypass on-off control circuit to be turned on, and simultaneously controlling the controllable switch to be turned off includes: controlling the discharge switch tube in the corresponding bypass on-off control circuit to be connected and simultaneously controlling the controllable switch to be disconnected;

when the preset condition is the first cut-in preset condition, step S102 includes: controlling the conduction of a charging switch tube in the corresponding main loop on-off control circuit; then controlling a charging switch tube in the corresponding bypass on-off control circuit to be turned off, and simultaneously controlling the controllable switch to be turned off;

when the preset condition is the second cut-in preset condition, step S102 includes: controlling the conduction of a discharge switch tube in the corresponding main loop on-off control circuit; and then the discharge switch tube in the corresponding bypass on-off control circuit is controlled to be turned off, and the controllable switch is controlled to be turned off at the same time.

Optionally, when the preset condition is the first cut-out preset condition or the third cut-out preset condition, in step S102, after controlling the charging switch tube in the corresponding bypass on-off control circuit to be turned on and controlling the controllable switch to be turned off at the same time, the method further includes: controlling a charging switch tube in the corresponding main loop on-off control circuit to be turned off;

when the preset condition is the second cut-out preset condition or the fourth cut-out preset condition, in step S102, after controlling the discharge switch tube in the corresponding bypass on-off control circuit to be turned on and simultaneously controlling the controllable switch to be turned off, the method further includes: and controlling the discharge switch tube in the corresponding main loop on-off control circuit to be switched off.

Optionally, the operating parameters include: voltage, SOC, SOH, or average temperature.

Optionally, step S104 includes: controlling the controllable switch to close.

Optionally, after step S104, the method further includes:

s105, updating parameters of the corresponding battery clusters, and controlling the corresponding power converters to normally operate;

and repeatedly executing S101 to S105 until the battery modules in each battery cluster meet the corresponding preset condition.

Optionally, when there is no inductor in the buffer device, before step S102, the method further includes:

s201, limiting the current on the direct current bus of the corresponding power converter within a preset current range.

Optionally, step S201 includes:

controlling the current on the direct current bus of the corresponding power converter to be reduced to the preset current range;

and controlling the corresponding power converter to carry out wave sealing operation.

Optionally, a switch box is further disposed between each battery cluster and the corresponding power converter, and when a main circuit switch is included in the switch box, step S201 includes:

and controlling the corresponding main loop switch to be switched off.

Optionally, before step S101, the method further includes:

s301, performing power-on self-test, and controlling a path between the battery cluster and the corresponding power converter and controlling the buffer circuit to be in a state of not absorbing a voltage spike when a self-test result is normal;

s302, detecting parameters of the battery cluster, and setting a reference range of operation parameters; all switches in each battery module are controlled to be switched off;

and S303, controlling each battery module to be put into the battery cluster according to an operation mode, and controlling the corresponding power converter to normally operate.

Optionally, the operation mode is: a charging mode or a discharging mode;

all include in main loop on-off control circuit in the battery module and the bypass on-off control circuit: the charging switch tube and the discharging switch tube, then:

when the operation mode is the charging mode, controlling each battery module to be put into the battery cluster according to the operation mode, including: controlling the conduction of a charging switch tube in each main loop on-off control circuit;

when the operation mode is the discharge mode, controlling each battery module to be put into the battery cluster according to the operation mode, including: and controlling the conduction of the discharge switch tube in each main loop on-off control circuit.

According to the energy storage system provided by the invention, the control unit can control each battery module to switch in or switch out the corresponding battery cluster when the corresponding preset condition is met, so that the currently accessed battery module in the battery cluster can be adjusted in real time, and further, each battery module can meet the corresponding preset condition one by one, namely, the same state is achieved, for example, SOC balance is realized; and at the same time, no energy waste is caused. In addition, the energy storage system is provided with at least one buffer circuit, which can absorb the voltage spike caused by switching in or switching out any battery module in the corresponding battery cluster, i.e. absorb the energy impact caused by the voltage sudden change, thereby avoiding the corresponding device from bearing larger voltage/current stress.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 and fig. 2 are two schematic structural diagrams of an energy storage system according to an embodiment of the present invention;

fig. 3 and fig. 4 are schematic structural diagrams of two other structures of a battery module according to an embodiment of the invention;

fig. 5 to fig. 8 are four flowcharts of a control method of an energy storage system according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

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

The invention provides an energy storage system, which is used for realizing SOC balance of a battery module and avoiding energy waste.

Referring to fig. 1, the energy storage system includes: a control unit (not shown), at least one battery cluster, at least one snubber circuit 101 and at least one power converter 102; wherein:

the battery cluster comprises a plurality of battery modules (such as PACK1, PACK2 and PACK3 … PACKn shown in fig. 1) connected in series, and two ends of each battery module after being connected in series are used for connecting with a direct current bus of a corresponding power converter 102; and a bus capacitor C1 is arranged between the positive electrode and the negative electrode of the direct current bus.

In practical applications, a switch box 103 may be disposed between each battery cluster and the corresponding power converter 102, and the bus capacitor C1 and the main circuit switches S1 and S2 are disposed inside the switch box 103, so as to control on/off between the battery cluster and the power converter 102.

It is noted that the energy storage system may include a plurality of configurations as shown in fig. 1, wherein each power converter 102 may be a DCAC converter, an ac side of which is connected to a grid and/or a load; each power converter 102 may also be a DCDC converter, and each DCDC converter may be merged to the dc side of the inverter unit of the photovoltaic power generation system, or may be connected to the grid and/or the load through a DCAC converter equipped in the energy storage system.

No matter what structure is adopted, the control unit in the energy storage system can control each battery module to switch in or switch out the corresponding battery cluster when the corresponding preset conditions are met; specifically, in a certain battery cluster, if a battery module meets a cut-out preset condition, such as full charge, empty or abnormal or fault light occurrence, the control unit controls the battery module to cut out the battery cluster; if the battery modules meet the cut-in preset condition, for example, all the battery modules are fully charged or emptied, the previously cut-out battery modules need to be cut into the battery cluster again to realize subsequent unified operation, or when the set parameters of full charge or emptying are changed, or a fault battery module is repaired, or a new battery module needs to be put into operation, the control unit controls the battery modules to be cut into the battery cluster. That is, the control unit can adjust the battery modules accessed to the battery cluster in real time, and only the battery modules which do not meet the corresponding preset conditions are left to continue to be put into the current operation mode, such as the charging mode or the discharging mode, so that each battery module can meet the corresponding preset conditions one by one until all the battery modules in the battery cluster reach the same state, such as the SOC balance is realized, and then the adjustment of the access of the battery modules to the battery cluster can be stopped. In addition, the scheme does not need to dissipate the energy of the battery module with a large SOC in the form of heat, so that the energy is not wasted. In addition, in the traditional energy storage system, no matter the battery module adopts active equalization or passive equalization, the equalization current of the battery module is milliampere, the equalization speed is relatively slow, and the equalization time is relatively constant. However, the energy storage system in this embodiment can increase the equalizing speed by 10 times or more through the above process.

In practical application, when any battery module in the battery cluster is switched in or switched out, the voltage on the bus capacitor C1 on the dc side of the power converter 102 cannot change suddenly, so that a voltage difference of one battery module exists between the voltage of the battery cluster and the voltage on the bus capacitor C1; if the current path of the battery cluster is directly switched in or out, voltage spikes can occur on the current path of the battery cluster, so that partial devices on the current path bear large voltage/current stress, and the safety is affected. Therefore, when a battery module in any battery cluster is switched in or switched out, the control unit controls the corresponding buffer circuit 101 to absorb the voltage spike, so that each device on a current path in the battery cluster is ensured not to bear large voltage/current stress, and the safety is improved.

Specifically, referring to fig. 1, the buffer circuit 101 includes: a controllable switch S3 and a snubber device connected in parallel. When a battery module exists in a corresponding battery cluster and is switched in or out, the controllable switch S3 is in an off state, so that the buffer device is applied and absorbs voltage spikes; when the voltage difference between the voltage of the corresponding battery cluster and the bus capacitor C1 is smaller than a preset difference value, the controllable switch S3 is in a closed state, so that the buffer device is bypassed, and the voltage spike is stopped being absorbed.

In practical application, when the voltage of the battery cluster changes, the voltage on the direct current bus connected with the battery cluster changes rapidly, and the voltage on the bus capacitor C1 cannot change suddenly, so that the buffer circuit 101 only needs to buffer the voltage difference between the direct current bus and the bus capacitor C1; therefore, the snubber circuit 101 may be disposed at any position on the dc bus, for example, on the dc bus between the battery cluster and the switch box 103 shown in fig. 1, on the dc bus between the switch box 103 and the power converter 102, or on the dc bus (positive and negative transmission branches) in the switch box 103. Alternatively, the buffer circuit 101 may be connected in series with the bus capacitor C1 between the positive and negative poles of the dc bus, that is, one end of the bus capacitor C1 may be disposed between the positive and negative pole transmission branches in the switch box 103. Depending on the specific application environment, are all within the scope of the present application.

As shown in fig. 1, the buffer device specifically includes: a resistor R and an inductor L which are connected in parallel; due to the existence of the inductor L, when the voltages at two ends of the inductor L are suddenly changed, the corresponding voltage peak can be absorbed; therefore, when the battery module is switched in or switched out, the corresponding operation can not cause electric arcs; the corresponding battery cluster can be switched in or switched out on load, namely, the current on the direct current bus is kept to be the magnitude in the normal running state, and the corresponding battery module is switched in or switched out. And, when the controllable switch S3 is closed, the resistor R can discharge energy to the inductor L.

In practical application, the buffer device can only comprise a resistor R, and the resistor R can still absorb voltage spikes when the battery module is switched in or switched out; however, if any battery module needs to be switched in or out, the voltages at the two ends of the corresponding switch will suddenly change before and after the operation, and an arc is easy to occur; therefore, preferably, the current on the dc bus is limited to a predetermined range, such as zero, and then the corresponding battery module is switched in or out to avoid the generation of the arc.

In practical applications, the control unit of the energy storage system may be in any form, such as a BMS (battery management system) shown in fig. 2, and the BMS specifically includes: a SMU (system Battery Management Unit), a CMU (Cell monitor Unit) of each Battery cluster, and a BMU (Battery Management Unit) disposed inside each Battery module;

the SMU, the CMU and the BMU are in communication connection step by step; as shown in fig. 2, in each battery cluster, each BMU is connected to a CMU in a hand-held communication manner, but in practical application, each BMU is not limited to this, as long as each BMU can communicate with a corresponding CMU, and each CMU can communicate with an SMU.

The buffer circuit 101 is controlled by the CMU of the corresponding cell cluster. In practice, the main circuit switches S1 and S2 in the switch box 103 are also controlled by the CMU of the corresponding battery cluster. Additionally, the respective power converters 102 may also be communicatively connected to CMUs of the same battery cluster. Furthermore, parameter monitoring, battery module switching-in and switching-out control, buffer control, whether to put into operation control, charge and discharge mode control and the like can be realized by the CMU of one battery cluster. Furthermore, both the CMU and the bus capacitor C1 may be disposed in the switch box 103 (as shown in fig. 2), although the CMU may be independently disposed outside the switch box 103, and in practical applications, the bus capacitor C1 may be implemented by a support capacitor on the battery side of the power converter 102, and does not necessarily need to be additionally disposed; depending on the specific application environment, are all within the scope of the present application.

In practical application, referring to fig. 1 or fig. 2, each battery module mainly includes: the battery comprises a battery body, a main loop on-off control circuit 201 and a bypass on-off control circuit 202 (the battery modules are identical in structure and are only displayed in the nth battery module PACKn); wherein:

the battery body is connected with the positive electrode and the negative electrode of the battery module through the main loop on-off control circuit 201, and the bypass on-off control circuit 202 is arranged between the positive electrode and the negative electrode of the battery module; furthermore, the main circuit on-off control circuit 201 and the bypass on-off control circuit 202 may be controlled by a control unit or a BMU.

Under the normal operation condition, the main loop on-off control circuit 201 is a closed circuit, the bypass on-off control circuit 202 is an open circuit, and the corresponding battery body is connected to the corresponding battery cluster. When a certain battery module needs to be cut out, the control unit or the CMU controls the bypass on-off control circuit 202 to be on and the main loop on-off control circuit 201 to be off directly through the BMU, and simultaneously the control unit or the CMU controls the controllable switch S3 in the buffer circuit 101 to be in an off state. When a certain battery module needs to be switched in, the control unit or the CMU controls the bypass on-off control circuit 202 to be open and the main loop on-off control circuit 201 to be closed again through the BMU, and the control unit or the CMU controls the controllable switch S3 in the buffer circuit 101 to be in an open state.

It should be noted that, the main circuit on-off control circuit 201 and the bypass on-off control circuit 202 may both include: a single-path bidirectional switch, as shown in fig. 1 and 3 (only the nth battery module PACKn is shown as an example in fig. 3, and the structures in the other battery modules are the same), such as a relay; at this time, the control unit or BMU can realize charging or discharging of the corresponding battery body by controlling the bidirectional switch in the main loop on-off control circuit 201, and can realize a charging bypass or a discharging bypass of the corresponding battery body by controlling the bidirectional switch in the bypass on-off control circuit 202. However, when any one of the main loop on-off control circuit 201 and the bypass on-off control circuit 202 is controlled to be switched from a closed circuit to an open circuit, since the control signal is inevitably delayed, in practical application, both the main loop and the bypass on-off control circuit are closed circuits, and thus, the corresponding battery body is short-circuited, and the safety of the battery body is threatened; therefore, when both of them are controlled to be on and off, it is necessary to perform control with a dead zone, that is, control one of them to be off and then control the other to be on, which causes the battery cluster to be off and have no current.

Preferably, in practical application, the main circuit on-off control circuit 201 and the bypass on-off control circuit 202 may be respectively configured to include two unidirectional switch sets, that is, the main circuit on-off control circuit 201 and the bypass on-off control circuit 202 are both configured to include: the charging switch and the discharging switch are provided with corresponding switch arrays in each battery module. At this time, the control unit or the BMU controls the charging switch in the main loop on-off control circuit 201 to realize charging of the corresponding battery body, controls the discharging switch in the main loop on-off control circuit 201 to realize discharging of the corresponding battery body, controls the charging switch in the bypass on-off control circuit 202 to realize a charging bypass of the corresponding battery body, and controls the discharging switch in the main bypass on-off control circuit 202 to realize a discharging bypass of the corresponding battery body.

In practical applications, the charging switch and the discharging switch may be arranged in inverse parallel, as shown in fig. 2, in the main loop on-off control circuit 201, the charging switch includes: a charging switch tube (such as K1-1, K1-2, K1-3 … K1-n shown in FIG. 2) and a charging diode, and a discharging switch comprises: discharge switch tubes (such as K4-1, K4-2, K4-3 … K4-n shown in FIG. 2) and discharge diodes; in the bypass on-off control circuit 202, the charging switch includes: a charging switch tube (such as K2-1, K2-2, K2-3 … K2-n shown in FIG. 2) and a charging diode, and a discharging switch comprises: discharge switch tubes (such as K3-1, K3-2, K3-3 … K3-n shown in FIG. 2) and discharge diodes; each diode is connected in series with the body diode in the corresponding switch tube in the reverse direction.

Alternatively, the charging switch and the discharging switch may be arranged in reverse series, as shown in fig. 4 (only the nth battery module PACKn is taken as an example in fig. 4, and the structures of the other battery modules are the same), at this time, the charging switch includes the charging switch tube, the discharging switch includes the discharging switch tube, and the charging switch tube and the discharging switch tube both have body diodes and are connected in reverse series; and then the body diode in the discharge switch tube and the charge switch tube form a branch in the charging direction of the battery cluster, and the body diode in the charge switch tube and the discharge switch tube form a branch in the discharging direction of the battery cluster.

No matter which way is adopted as shown in fig. 2 and fig. 4, when one switching tube in any one of the main loop on-off control circuit 201 and the bypass on-off control circuit 202 is closed, the diode in the same switching tube in series as shown in fig. 2 or the body diode of the other switching tube in fig. 4 in the other control circuit automatically realize reverse cut-off, thereby avoiding short circuit of the corresponding battery body; therefore, it is not necessary to control another control circuit to switch to the open circuit first, and dead-zone-free switching can be realized.

Another embodiment of the present invention further provides a control method of an energy storage system, which is applied to the control unit in the energy storage system according to any of the above embodiments; the specific structure and principle of the energy storage system can be referred to the above embodiments, and are not described in detail.

As shown in fig. 5, the control method includes:

s101, judging whether each battery module in the corresponding battery cluster of the energy storage system meets corresponding preset conditions.

The preset condition may be a cut-out preset condition or a cut-in preset condition; for example, when a certain battery module in the same battery cluster is full, or is empty, or has a fault, or needs to be replaced with a new battery module, etc., the preset conditions for switching out are met; when the set parameters of full charge or emptying are changed, or the fault battery module is repaired, or a new battery module needs to be put into operation, the cut-in preset condition is met; or when the operation mode of the battery cluster needs to be adjusted, for example, from the charging mode to the discharging mode, or from the discharging mode to the charging mode, all the battery modules may be adjusted to the same state, or may be considered to satisfy the cut-in preset condition; depending on the specific application environment, are all within the scope of the present application.

If any battery module meets the corresponding preset condition, step S102 is executed.

S102, controlling the corresponding battery modules to cut in or cut out a battery cluster; meanwhile, the corresponding buffer circuit in the energy storage system is controlled to absorb the voltage spike caused by switching in or switching out the corresponding battery module.

For the condition of a single-path bidirectional switch, when a certain battery module is cut out, the bidirectional switch in the main loop on-off control circuit needs to be controlled to be turned off, and meanwhile, the controllable switch in the buffer circuit is controlled to be turned off to absorb a voltage spike; and then the bidirectional switch in the bypass on-off control circuit is controlled to be conducted. When a certain battery module is switched in, the bidirectional switch in the bypass on-off control circuit needs to be controlled to be switched off, and the controllable switch is controlled to be switched off to absorb a voltage spike; and then the bidirectional switch in the main loop on-off control circuit is controlled to be conducted. That is, on-off control with a dead zone is required to avoid short-circuiting to the battery body.

For the condition of a two-way one-way switch group, when a certain battery module is cut out, the bypass on-off control circuit can be controlled to be switched on, and meanwhile, the controllable switch is controlled to be switched off to absorb a voltage spike; and then the main loop on-off control circuit can be controlled to be turned off. When a certain battery module is switched in, the on-off control circuit of the main loop can be controlled to be conducted; and then the bypass on-off control circuit is controlled to be turned off, and the controllable switch is controlled to be turned off to absorb the voltage spike. That is, a short circuit to the battery body is prevented by the reverse blocking function of the charge switch and the discharge switch thereof, and thus, a dead zone-free control can be realized without any cut-in or cut-out operation causing a current interruption of the battery pack.

S103, judging whether the voltage difference between the battery cluster and the corresponding bus capacitor is within a preset voltage range.

If the voltage difference is not within the preset voltage range, the buffer circuit continuously absorbs the voltage spike. If the voltage difference is within the preset voltage range, step S104 is executed.

And S104, controlling the buffer circuit to stop absorbing the voltage spike.

When the voltage difference between the two ends of the buffer device in the buffer circuit, for example, the voltage difference between the two ends of the inductor L in fig. 2, is within the preset voltage range, the controllable switch may be controlled to be closed, so as to bypass the buffer device, avoid the inductor L in fig. 2 from consuming energy continuously, and release the energy in the inductor L through the resistor R.

In a specific embodiment, the preset condition may be any one of the following conditions: when the battery cluster is charged, the operation parameter of the corresponding battery module reaches a first cut-out preset condition of a preset upper limit value; when the battery clusters are discharged, the operation parameters of the corresponding battery modules reach a second switching-out preset condition of a preset lower limit value; when the battery clusters are charged, a third switching-out preset condition is adopted when the corresponding battery module is abnormal or fails; when the battery clusters are discharged, the corresponding battery modules are switched out to preset conditions in case of abnormity or fault; a first cut-in preset condition that the charging bypass state needs to be recovered to the charging state; a second cut-in preset condition for restoring from the discharge bypass state to the discharge state is required. Wherein the operating parameter may be: voltage, SOC, SOH (state of health), average temperature, etc., which are not specifically limited herein, may be determined according to the application environment, and are within the scope of the present application.

Use main loop on-off control circuit and bypass on-off control circuit in the battery module all to include double-circuit unidirectional switch group as an example, this moment: if the preset condition is the first cut-out preset condition or the third cut-out preset condition, step S102 includes: the charging switch tube in the corresponding bypass on-off control circuit is controlled to be switched on, and the controllable switch is controlled to be switched off; and then, the charging switch tube in the corresponding main loop on-off control circuit can be controlled to be turned off. If the preset condition is the second cut-out preset condition or the fourth cut-out preset condition, step S102 includes: the discharge switch tube in the corresponding bypass on-off control circuit is controlled to be conducted, and meanwhile, the controllable switch is controlled to be disconnected; and then, the discharge switch tube in the corresponding main loop on-off control circuit can be controlled to be turned off. If the preset condition is the first entry preset condition, step S102 includes: controlling the conduction of a charging switch tube in the corresponding main loop on-off control circuit; and then the charging switch tube in the corresponding bypass on-off control circuit is controlled to be turned off, and the controllable switch is controlled to be turned off at the same time. If the preset condition is the second cut-in preset condition, step S102 includes: controlling the conduction of a discharge switch tube in the corresponding main loop on-off control circuit; and then the discharge switch tube in the corresponding bypass on-off control circuit is controlled to be turned off, and the controllable switch is controlled to be turned off at the same time.

By adopting the control method provided by the embodiment, when the battery module is switched out or switched in, the switching of the switch array in the corresponding battery module and the input of the buffer circuit are reasonably controlled, so that the possible switch voltage/current peak on the main switch device can be effectively inhibited, and the energy impact caused by voltage sudden change can be absorbed.

When a certain battery module is full, discharged, failed or supplemented, the switch-out/switch-in operation of the switch array is combined with the input of the buffer circuit, so that the switch-out/switch-in of the module with current without dead zones can be realized. In addition, when the energy storage system is charged/discharged, the action of cutting off the battery module which possibly occurs does not need to break a main loop switch in a switch box, and dead-zone-free switching is realized.

Preferably, as shown in fig. 6, after step S104, the control method further includes:

and S105, updating the parameters of the corresponding battery cluster, and controlling the corresponding power converter to normally operate.

And repeatedly executing S101 to S105 until the battery modules in each battery cluster meet corresponding preset conditions.

For example, in a charging and discharging scene, each time a battery module is cut out, the access number of the battery modules in the battery cluster, the voltage of the battery modules, the system voltage and the like can be updated, so that charging and discharging can be continued, and other battery modules can be cut out one by one. After the SOC of each battery module is consistent, if a shutdown instruction is received, the battery system may be shut down and stopped. Other cases are similar and will not be described in detail.

As shown in fig. 7, the control method may further include, before step S101:

and S301, performing power-on self-test, and controlling a passage between the battery cluster and the corresponding power converter and controlling the buffer circuit to be in a state of not absorbing voltage spikes when the self-test result is normal.

S302, detecting parameters of the battery cluster, and setting a reference range of the operation parameters; and all switches in each battery module are controlled to be switched off.

And S303, controlling each battery module to be put into the battery cluster according to the operation mode, and controlling the corresponding power converter to normally operate.

The operation mode is as follows: a charging mode or a discharging mode. If the operation mode is the charging mode, controlling each battery module to be put into the battery cluster according to the operation mode, specifically: and controlling the conduction of the charging switch tube in each main loop on-off control circuit. And if the operation mode is a discharge mode, controlling each battery module to be put into the battery cluster according to the operation mode, specifically: and controlling the conduction of the discharge switch tube in each main loop on-off control circuit.

It should be noted that, when the control unit is specifically a BMS, the control method may be specifically implemented by any one of the management units, and the following specifically describes, by taking a CMU as an example, the control method in conjunction with the structure shown in fig. 2:

the system is started and carries out system self-test through the CMU and the BMU: detecting the access number n, the battery module voltage (such as Vmod _1, Vmod _2, Vmod _3 … Vmod _ n and system voltage Vsys shown in the figure), and disconnecting all the switching tubes (such as K1-n, K2-n, K3-n and K4-n in PACKn); the SOC state of the battery module can be known from the battery module voltage Vmod _ n. When the states of the respective battery modules are normal, the CMU closes the main circuit switches S1, S2 and the controllable switch S3.

If the operation mode is the charging mode, the CMU issues a power-on instruction to control each BMU to close the charging switch tube (for example, K1-n in PACKn) in the main loop on-off control circuit 201, and turn off other switch tubes. If the operation mode is the discharging mode, the CMU issues a power-on instruction to control each BMU to close a discharging switch tube (for example, K4-n in PACKn) in the main loop on-off control circuit 201, and turn off other switch tubes.

Then, the CMU acquires SOC information of each battery module according to OCV _ SOC calibration, which is a relationship between the voltage and the SOC, and issues a charging or discharging limit current Icn to the power converter 102.

(1) In the normal charging process, along with the increase of the voltage of the battery modules, when the mth battery module PACKm first reaches the preset upper limit value Vmodmax or the set high SOC threshold value, since the voltages of the other battery modules are all smaller than the preset upper limit value Vmodmax, the mth battery module PACKm needs to be bypassed, that is, the operation of switching out the main power loop is performed, and the remaining modules which are not fully charged are continuously charged.

In the charging process, the switching-out control logic of the mth battery module PACKm is as follows: k2 is closed and S3 is open → after RL absorption → S3 is closed.

Specifically, the charging switch tube K2-m in the bypass on-off control circuit 202 is controlled to be closed through the BMU of the mth battery module PACKm, the CMU controls the controllable switch S3 in the buffer circuit 101 to be opened at the same time, the buffer device is connected to the main loop, and the energy impact generated when the K2-m is closed is absorbed by the inductor L, so that the current impact cannot be generated after the voltage mutation. At this time, the charging switch tube K1-m in the main loop on-off control circuit 201 can be opened or not, if the control K1-m is opened, the control K1-m needs to be opened after the control K2-m is closed, so as to avoid the open circuit of the battery cluster. After the buffer circuit acts, when the voltage difference between the front and the back of the inductor L, namely the voltage difference between the voltage Ub of the battery cluster and the voltage Uc of the bus capacitor C1, is smaller than a certain threshold value, the controllable switch S3 is closed, the buffer device is bypassed, and the switching of the main power loop of the battery module is completed.

After the removal is complete, the power converter 102 continues to charge the remaining n-1 battery modules. The CMU updates parameters such as the number n of accesses to the modules, the voltage of the battery modules, and the like, and the remaining battery modules are continuously charged through the power converter 102, and the same logic is controlled until all the battery modules reach a preset upper limit value Vmodmax or a set SOC high threshold value.

(2) In the normal charging process, some battery module have been surely the back by the bypass, in the follow-up work engineering, when need cutting into the system with battery module, then can know by the battery module PACKm of bypass in, its inside switch array's state is: k2-m is closed, while K1-m, K3-m and K4-m are all open. Assuming that the battery module PACKm needs to be switched into the system, the switching-in control logic of the battery module is as follows in the charging process: k1 closed → K2 open and S3 open → after RL absorption → S3 closed.

Specifically, the BMU of the battery module PACKm controls K1-m to be closed firstly and then controls K2-m to be opened, and the CMU controls the controllable switch S3 to be opened simultaneously and connects the buffer device into the main loop, so that energy impact generated when the K2-m is opened is absorbed by the inductor L, and current impact cannot be generated after voltage mutation. After the buffer circuit acts, when the voltage difference between the front and the back of the inductor L, namely the voltage difference between Ub and Uc, is smaller than a certain threshold value, the controllable switch S3 and the bypass buffer device are closed, and the battery module is switched into the main power loop to complete the operation.

After the cut-in is completed, the CMU updates parameters such as the access number n of the modules, the voltage of the battery modules and the like, all the battery modules are continuously charged through the power converter 102, and all the bypassed battery modules in the system can be recovered through the same control logic.

(3) In the normal discharge process, along with the reduction of the voltage of the battery modules, when the mth battery module PACKm first reaches the preset lower limit value Vmodmin or the set SOC low threshold value, since the voltages of the other battery modules are all greater than the preset lower limit value Vmodmin, the mth battery module PACKm needs to be bypassed at this time, that is, the operation of cutting out the main power loop is performed, and the rest of the modules which are not emptied continue to be discharged.

In the discharging process, the module switching control logic of the mth battery module PACKm is as follows: k3 is closed and S3 is open → K4 is open → after RL absorption → S3 is closed.

Specifically, K3-m is controlled to be closed through a BMU of the battery module PACKm, a CMU controls a controllable switch S3 to be opened at the same time, a buffer device is connected into a main loop, and then K4-m is opened, and energy impact generated when K3-m is closed is absorbed by an inductor L, so that current impact cannot be generated after voltage mutation. After the buffer circuit acts, when the voltage difference between the front and the back of the inductor L, namely the voltage difference between Ub and Uc, is smaller than a certain threshold value, the controllable switch S3 and the bypass buffer device are closed, and the switching-out of the main power loop of the battery module is completed.

After the removal is complete, the power converter 102 continues to discharge the remaining n-1 battery modules. The CMU updates parameters such as the access number n of the modules, the voltage of the battery modules and the like, continues to discharge the rest of the batteries through the power converter 102, and has the same control logic until all the battery modules reach a preset lower limit value Vmodmin or a set SOC low threshold value.

(4) In the normal discharge process, some modules have been cut out the back by the bypass, in the follow-up work engineering, when need cutting into the system with battery module, then can know by the battery module PACKm of bypass in, its switch array state is: k3-m is closed, and K1-m, K2-m and K4-m are all in open state. Assuming that the battery module PACKm needs to be switched into the system, the switching control logic of the battery module is as follows in the discharging process: k4 closed → K3 open and S3 open → after RL absorption → S3 closed.

Specifically, the BMU of the battery module PACKm controls K4-m to be closed firstly and then controls K3-m to be opened, and the CMU controls the controllable switch S3 to be opened and connects the buffer device into the main loop at the same time, so that energy impact generated when the K3-m is opened is absorbed by the inductor L, and current impact cannot be generated after voltage mutation. After the buffer circuit acts, when the voltage difference between the front and the back of the inductor L, namely the voltage difference between Ub and Uc, is smaller than a certain threshold value, the controllable switch S3 and the bypass buffer device are closed, and the battery module is switched into the main power loop to complete the operation.

After the cut-in is completed, the CMU updates parameters such as the access number n of the modules, the voltage of the battery modules and the like, all the battery modules are continuously discharged through the power converter 102, and all the bypassed battery modules in the system can be recovered through the same control logic.

(5) The fault module switching-out control logic: when the system judges that one battery module is abnormal or has a fault and needs to be switched out, the system executes the switching-out operation of the battery module.

The switching-out control logic of the m-th battery module PACKm is the same as the switching-out logic during charging and discharging, namely, when the module is abnormal or has a fault, whether the main power loop is in a charging or discharging state is judged at the same time, and then the corresponding execution module switches out the control logic.

As can be seen from the above, under the configuration shown in fig. 2, the main circuit switch in the switch box does not need to be turned off, when a certain battery module is full, empty, or failed, or the module is supplemented, the main power circuit of the battery cluster can be switched on/off through the switch array, and the buffer circuit is combined, so that the battery module can be switched on/off quickly in the main power circuit, and the battery module can be switched on/off without dead zone in the charging and discharging process of the system.

Moreover, in the application of the energy storage system, the SOC calculation of the battery module is the basis of system control; in the embodiment, a centralized or distributed SOC state evaluation scheme is adopted to individually calculate the SOC of each battery module. Each battery module can carry out independent control according to the SOC state of self, has solved among the traditional algorithm after a certain module SOC is full of or empties, all modules all proofread and correct the problem that SOC is unanimous by force.

In addition, because the manufacture factory is different, the reasons such as production batch, electric core uniformity problem, when carrying out system's dilatation or module and changing, need carry out complicated benefit electricity operation to make the SOC of waiting to change the battery module keep unanimous with system SOC, then change, the fortune dimension process complex operation is complicated, and can't solve the vat effect problem of new and old battery module. The control method provided by the embodiment controls each battery module independently, solves the operation problem of capacity expansion or power supplement replacement, and can realize the purpose of replacing and using the battery modules immediately.

It should be noted that, as described in the above embodiment, when the inductor L exists in the buffer device, the battery module may be switched in or out with load; however, when there is no inductor L in the buffer device, if the battery module is still loaded to perform the corresponding operation, the corresponding switch may generate an arc during the operation, and there is an arc discharge risk, so at this time, the control method may be further as shown in fig. 8 (which is illustrated on the basis of fig. 5) on the basis of the above embodiment, that is, before step S102, the method further includes:

s201, limiting the current on the direct current bus of the corresponding power converter within a preset current range by the CMU.

The step S201 specifically includes:

(1) and the CMU controls the current on the direct current bus of the corresponding power converter to be reduced to a preset current range.

(2) The CMU controls the corresponding power converter to carry out wave-sealing operation; alternatively, the CMU may directly control the corresponding main circuit switch to be turned off. Depending on the specific application environment, are all within the scope of the present application.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended 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. An energy storage system, comprising: the device comprises a control unit, at least one battery cluster, at least one buffer circuit and at least one power converter; wherein:

2. The energy storage system of claim 1, wherein the snubber circuit comprises: the controllable switch and the buffer device are connected in parallel;

3. The energy storage system of claim 2, wherein the buffer device comprises: a resistor, or a resistor and an inductor connected in parallel.

4. The energy storage system of claim 1, wherein the snubber circuit is disposed on the dc bus, or the snubber circuit and the bus capacitor are connected in series between a positive pole and a negative pole of the dc bus.

5. The energy storage system of any one of claims 1-4, wherein the battery module comprises: the battery comprises a battery body, a main loop on-off control circuit and a bypass on-off control circuit; wherein:

6. The energy storage system of claim 5, wherein the main loop on-off control circuit and the bypass on-off control circuit each comprise: a two-way one-way switch group; the two-way one-way switch group comprises: a charge switch and a discharge switch; the control unit controls the charging switch in the main loop on-off control circuit to realize charging of the corresponding battery body, controls the discharging switch in the main loop on-off control circuit to realize discharging of the corresponding battery body, controls the charging switch in the bypass on-off control circuit to realize charging bypass of the corresponding battery body, and controls the discharging switch in the main bypass on-off control circuit to realize discharging bypass of the corresponding battery body;

alternatively, the first and second electrodes may be,

7. The energy storage system of claim 6, wherein the charge switch comprises: the charging switch tube and the charging diode are reversely connected in series with the body diode in the charging switch tube; the discharge switch includes: the discharge switch tube and a discharge diode are reversely connected in series with a body diode in the discharge switch tube; the charging switch is connected with the discharging switch in an inverse parallel mode;

alternatively, the first and second electrodes may be,

8. The energy storage system of claim 5, wherein a switch box is further disposed between each of the battery clusters and the corresponding power converter, and the switch box comprises: a main circuit switch.

9. The energy storage system according to any one of claims 1-4, wherein the control unit is a Battery Management System (BMS), and the BMS comprises: a system battery management unit SMU, a battery cluster management unit CMU of each battery cluster and a battery management unit BMU arranged in each battery module;

the SMU, the CMU and the BMU are in communication connection step by step;

the CMU is communicatively coupled to the power converter.

10. The energy storage system of any of claims 1-4, wherein the power converter is a DCAC converter; alternatively, the first and second electrodes may be,

11. A control method of an energy storage system, characterized by being applied to a control unit in the energy storage system according to any one of claims 1-10; the control method comprises the following steps:

and S104, controlling the buffer circuit to stop absorbing the voltage spike.

12. The control method of the energy storage system according to claim 11, wherein the preset condition is a cut-out preset condition or a cut-in preset condition; the buffer circuit includes: the controllable switch and the buffer device are connected in parallel; and in main loop on-off control circuit and the bypass on-off control circuit in the battery module, all include: a single-pass bi-directional switch; then:

13. The control method of the energy storage system according to claim 11, wherein the preset condition is a cut-out preset condition or a cut-in preset condition; the buffer circuit includes: the controllable switch and the buffer device are connected in parallel; the main loop on-off control circuit and the bypass on-off control circuit in the battery module respectively comprise two unidirectional switch sets; then:

14. The method according to claim 13, wherein when the preset condition is the cut-out preset condition, in step S102, after controlling the corresponding bypass on-off control circuit to be turned on and the controllable switch to be turned off, the method further comprises: and controlling the corresponding main loop on-off control circuit to be switched off.

15. The control method of the energy storage system according to claim 13, wherein the cut-out preset condition is any one of:

the preset cut-in condition is any one of the following conditions:

16. The method for controlling the energy storage system according to claim 15, wherein the main loop on-off control circuit and the bypass on-off control circuit in the battery module each comprise: the charging switch tube and the discharging switch tube, then:

17. The method according to claim 16, wherein when the preset condition is the first cut-out preset condition or the third cut-out preset condition, in step S102, after controlling the charging switch tube in the corresponding bypass on-off control circuit to be turned on and the controllable switch to be turned off, the method further comprises: controlling a charging switch tube in the corresponding main loop on-off control circuit to be turned off;

18. The energy storage system control method according to any one of claims 15 to 17, wherein the operation parameters include: voltage, remaining charge SOC, battery health SOH, or average temperature.

19. The control method of the energy storage system according to any one of claims 13 to 14 and 16 to 17, wherein the step S104 includes: controlling the controllable switch to close.

20. The control method of the energy storage system according to any one of claims 11 to 17, further comprising, after step S104:

21. The method according to any one of claims 11 to 17, wherein when there is no inductance in the snubber device, before step S102, the method further includes:

22. The control method of the energy storage system according to claim 21, wherein step S201 includes:

23. The method of claim 21, wherein a switch box is further disposed between each battery cluster and the corresponding power converter, and when a main circuit switch is included in the switch box, step S201 includes:

and controlling the corresponding main loop switch to be switched off.

24. The method according to any one of claims 11 to 17, characterized by further comprising, before step S101:

25. The control method of the energy storage system according to claim 24, wherein the operation mode is: a charging mode or a discharging mode;