Energy storage battery heating method, apparatus, and medium

Abstract

The application discloses an energy storage battery heating method, device and medium; the method comprises the following steps: constructing a current reference of a battery cluster, the current reference comprising a direct current component and an alternating current component; performing phase distribution on the alternating current component corresponding to each battery cluster, so that the vector sum of the alternating current components corresponding to all the battery clusters after the phase distribution is zero; generating a heating current instruction of the battery cluster according to the current reference after the phase distribution and inputting the heating current instruction to a corresponding bidirectional DC / DC circuit. The device and the medium are used to implement the above method. The application has the beneficial effects that the technical scheme of the application is completely implemented based on the existing current control architecture, does not need additional devices such as heating sheets, PTCs and H-bridge heating units, avoids the cost increase and reliability risks caused by hardware expansion, and is convenient for direct deployment in the existing energy storage platform.

Description

Technical Field

[0001] This application relates to the field of new energy power generation technology, and in particular to a method, equipment and medium for heating energy storage batteries. Background Technology

[0002] Existing energy storage battery heating methods are mainly divided into two categories: external heating methods and current-based active heating methods.

[0003] External heating methods typically rely on devices such as heating films, PTC heaters, air ducts, or liquid-cooled thermal management. While these methods do not require changes to the circuit structure, heating devices, piping, pumps, valves, and control modules all need to be additionally configured, significantly increasing system costs. At the same time, the heat from external heating must be transferred through the casing and structural components before entering the battery cell, resulting in lower thermal efficiency, slower heating rates, and insufficient responsiveness to the overall heating needs of large-scale energy storage systems.

[0004] Current-based active heating methods generate heat within the battery through resistive losses by increasing the charging / discharging current, injecting pulse current, or adding AC components. While these methods can directly generate heat within the cell, they generally suffer from the following engineering problems: First, the heating current directly acts on the bidirectional DC / DC circuit and the DC bus. If multiple battery clusters operate simultaneously, their power fluctuations will be superimposed on the common bus, causing significant bus voltage swings. Second, when power disturbances on the bus side increase, the DC voltage control loop and grid-connected output current control loop of the PCS (Power Conversion System) will be forced to adjust frequently, leading to increased grid-connected current distortion, affecting output current quality, and potentially triggering protection. Furthermore, existing pulse or AC heating methods are mostly based on single-cluster or local structures, lacking an overall coordination mechanism for multi-cluster parallel architectures, making it difficult to suppress bus disturbances through frequency or phase management. Summary of the Invention

[0005] One objective of this application is to provide a method for heating energy storage batteries that can solve at least one of the defects in the aforementioned background technology.

[0006] Another object of this application is to provide an electronic device capable of implementing a method for heating an energy storage battery that solves at least one of the defects in the above-mentioned background art.

[0007] Another object of this application is to provide a computer-readable storage medium capable of implementing a method for heating an energy storage battery that addresses at least one of the deficiencies in the aforementioned background technology.

[0008] To achieve at least one of the above objectives, the technical solution adopted in this application is as follows: a method for heating an energy storage battery, applied to a topology in which multiple battery clusters are connected to a common DC bus via corresponding bidirectional DC / DC circuits, comprising the following steps: constructing a current reference for the battery clusters, the current reference including a DC component and an AC component; wherein, the DC component is used to maintain the charging and discharging of the battery clusters, and the AC component is used to control the heating of the battery clusters; performing phase allocation on the AC component corresponding to each battery cluster, such that the vector sum of the AC components corresponding to all battery clusters after phase allocation is zero; generating a heating current command for the battery clusters based on the current reference after phase allocation and inputting it to the corresponding bidirectional DC / DC circuit.

[0009] Preferably, based on the different temperature states of each battery cluster, the phase allocation of the AC component corresponding to each battery cluster includes the following process: determining the amplitude of the AC component required for heating each battery cluster according to the temperature of each battery cluster; uniformly distributing the determined amplitudes of each AC component, and calculating the phase of each AC component based on the uniformly distributed amplitudes, so that the vector sum of all AC components is zero.

[0010] Preferably, the calculation process for phase shift based on the amplitude equalization distribution of each AC component is as follows: sum the amplitudes of the AC components corresponding to all the battery clusters to obtain the amplitude sum S; mark the maximum amplitude A of the AC components corresponding to all the battery clusters. max If there are two battery clusters, the amplitudes of the AC components corresponding to the two battery clusters are evenly distributed so that both take the maximum amplitude A. max Simultaneously, the phases of the AC components corresponding to the two battery clusters are out of phase; if the number of battery clusters exceeds two, according to A max with SA max The phase of the AC component corresponding to each battery cluster is determined by a grouped vector synthesis algorithm based on the relationship between the components.

[0011] Preferably, when the number of battery clusters n > 2, and A max ≥SA max At that time, the working process of the group vector synthesis algorithm is as follows: the maximum amplitude A is... max The corresponding battery clusters are designated as the first group, while the remaining battery clusters are designated as the second group; the amplitude of the battery clusters in the first group remains unchanged, and the amplitude of the AC component corresponding to each battery cluster in the second group is increased by (2A). max -S) / (n-1); Set the phase of the AC component corresponding to the battery cluster of the second group to be in phase and out of phase with the phase of the AC component corresponding to the battery cluster of the first group.

[0012] Preferably, when the number of battery clusters n > 2, and A max <SA max In this process, among the amplitudes of the AC components corresponding to all the battery clusters, several remaining amplitudes are added to the largest amplitude and then summed. If the sum of the summed amplitudes is equal to the sum of the remaining amplitudes, the working process of the group vector synthesis algorithm is as follows: the battery clusters corresponding to the summed amplitudes are taken as the first group, and the remaining battery clusters are taken as the second group; the phases of the AC components corresponding to each group of battery clusters are the same, and the phases of the AC components corresponding to the two groups of battery clusters are out of phase.

[0013] Preferably, when the number of battery clusters n > 2, and A max <SA max The working process of the grouped vector synthesis algorithm is as follows: all the battery clusters are divided into three groups, the phases of the AC components corresponding to the battery clusters in each group are the same, and the sum of the amplitudes of the AC components corresponding to the three groups satisfies the triangle relationship; taking the phase of the AC component corresponding to one group of battery clusters as a reference, the phases of the AC components corresponding to the other two groups of battery clusters are calculated by using the cosine theorem.

[0014] Preferably, the specific grouping process for all the battery clusters is as follows: take the largest amplitude value A. max The target amplitude is used as the initial value, and it is determined whether the target amplitude is greater than or equal to S / 3. If the target amplitude is greater than or equal to S / 3, the battery cluster corresponding to the target amplitude is taken as the first group; if the target amplitude is less than S / 3, the current minimum amplitude A is used as the first group. min The target amplitude is added to the target amplitude to perform the target amplitude update process. After each round of target amplitude update, it is determined whether the target amplitude is greater than or equal to S / 3. If the target amplitude is still less than S / 3, the above target amplitude update process is repeated until the target amplitude is greater than or equal to S / 3. It is then determined whether the target amplitude is less than S / 2. If the target amplitude is less than S / 2, the battery clusters corresponding to all amplitudes in the target amplitude are taken as the first group. Otherwise, the battery clusters corresponding to the remaining amplitudes after the minimum amplitude of the last accumulated target amplitude is returned are taken as the first group. The target amplitude is reselected from the AC components corresponding to the remaining battery clusters and the above process is repeated to obtain the battery clusters of the second group. After the construction of the battery clusters of the first and second groups is completed, the remaining battery clusters are taken as the third group.

[0015] Preferably, the specific control of the bidirectional DC / DC circuit includes the following process: sampling the output voltage and current of each battery cluster and the battery temperature; determining the heating current command corresponding to each battery cluster based on the collected battery temperature and inputting it; calculating the current command value based on the power command of the battery cluster and the sampled output voltage; superimposing the calculated current command value with the input heating current command and comparing it with the sampled output current; sending the difference value to the PI controller to generate a duty cycle, thereby controlling the PWM generator to generate a drive signal to control the bidirectional DC / DC circuit.

[0016] An electronic device includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the above-described energy storage battery heating method.

[0017] A computer-readable storage medium storing a computer program; when the computer program is executed by a processor, the above-described energy storage battery heating method is implemented.

[0018] Compared with the prior art, the beneficial effects of this application are as follows:

[0019] (1) The technical solution of this application is based entirely on the existing current control architecture. It does not require additional devices such as heating elements, PTC, H-bridge heating units, etc., thus avoiding the cost increase and reliability risks brought about by hardware expansion, and is easy to deploy directly in the existing energy storage platform.

[0020] (2) By uniformly planning the frequency and phase of the heating AC components of each battery cluster, the periodic power disturbances generated by heating are mutually canceled on the system side, thereby reducing the voltage swing of the DC bus from the source.

[0021] (3) The amplitude and phase of the AC component can be configured independently between each battery cluster, so that each cluster can be heated differently according to the temperature difference without affecting the overall operation of the system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of one specific architecture of a traditional energy storage system.

[0023] Figure 2 This is a schematic diagram of the overall working steps of this application.

[0024] Figure 3 This is a schematic diagram illustrating the specific workflow of this application based on amplitude and phase allocation.

[0025] Figure 4 This is a schematic diagram of the control loop for the bidirectional DC / DC circuit based on amplitude and phase allocation in this application. Detailed Implementation

[0026] The present application will now be further described in conjunction with specific embodiments. It should be noted that, in the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0027] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0028] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0029] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0032] To facilitate understanding of the technical solution of this application, the basic architecture of a traditional energy storage system can be described below.

[0033] like Figure 1 As shown, traditional energy storage systems employ a topology where multiple battery clusters are connected to a common DC bus via corresponding bidirectional DC / DC circuits. For simplicity, the energy storage system is described as including two battery clusters, Bat#1 and Bat#2, two bidirectional DC / DC circuits (Bidirectional DC / DC#1 and Bidirectional DC / DC#), a DC / DC circuit, and a DC / AC circuit. The two battery clusters, Bat#1 and Bat#2, are connected in parallel to the DC bus via their respective bidirectional DC / DC circuits, enabling each battery cluster to independently receive current commands and perform charge / discharge control.

[0034] It is important to know that if any bidirectional DC / DC circuit injects a periodic alternating current into the battery side, its alternating current component will inevitably be reflected on the DC bus, forming a periodic power disturbance, and directly affecting the grid-connected current and current loop stability of the DC / AC circuit.

[0035] To address the aforementioned technical problems, one aspect of this application provides a method for heating an energy storage battery, applicable to a topology where multiple battery clusters are connected via a common DC bus through corresponding bidirectional DC / DC circuits. The basic principle is that the heating currents of different battery clusters satisfy a vector sum of zero. For example... Figure 2As shown, one preferred embodiment includes the following steps: constructing a current reference for the battery cluster, the current reference including a DC component and an AC component; wherein, the DC component is used to maintain the charging and discharging of the battery cluster, and the AC component is used to control the heating of the battery cluster; performing phase allocation on the AC component corresponding to each battery cluster, such that the vector sum of the AC components corresponding to all battery clusters after phase allocation is zero; generating a heating current command for the battery cluster based on the current reference after phase allocation and inputting it to the corresponding bidirectional DC / DC circuit.

[0036] It is understood that the technical solution of this application can enable battery clusters to obtain effective heating capabilities without adding any additional heating hardware or changing the existing power structure, while avoiding the system disturbances inherent in current-type heating. Specifically, the technical solution of this application centrally plans the various heating AC components and artificially sets their phase relationships, causing these heating AC components to cancel each other out on the system side, thus suppressing bus power fluctuations at the source. Because bus voltage fluctuations are significantly reduced, the DC voltage regulation pressure on the PCS is lowered, and the inverter output current is no longer additionally affected by heating behavior, thereby maintaining good grid-connected current quality and avoiding instability phenomena such as harmonic rise or frequent inverter power adjustments. In this way, the technical solution of this application achieves the goal of "local heat generation and system stability," providing a novel temperature rise control scheme for energy storage batteries that combines efficiency, cost, and grid-connected quality.

[0037] Specifically, for a single battery cluster k among the n battery clusters in an energy storage system, its current reference i k (t) can be represented as: i k (t)= i dc,k +A k ·sin(ω·t+ ).

[0038] In the formula, i dc,k A represents the DC component used to maintain the basic charge and discharge of battery cluster k. k ·sin(ω·t+ ) represents the AC component used to heat battery cluster k; where, A k ω represents the amplitude of the AC component, and ω represents the frequency of the AC component. Indicates the phase of the alternating component.

[0039] It is important to know that in order to ensure that the heating current of all battery clusters is canceled out on the bus, the following must be satisfied:

[0040] .

[0041] It is understandable that the heating temperature of a battery cluster is affected by the amplitude of the AC component. There are two scenarios regarding the temperature states of multiple battery clusters in an energy storage system: First, if the temperature states of all battery clusters are the same, then the heating temperature of all battery clusters is also the same, meaning the amplitude of the AC component corresponding to all battery clusters is the same. Second, if the temperature states of the multiple battery clusters are different, meaning at least two battery clusters have inconsistent temperature states, then the heating temperature of all battery clusters is also completely the same, meaning the amplitude of the AC component corresponding to all battery clusters differs. For ease of understanding, the phase allocation process of the AC component in these two scenarios will be described in detail below.

[0042] I. For the case where all battery clusters have the same temperature state.

[0043] In this embodiment, the AC component corresponding to each battery cluster can be considered as a current vector; where the amplitude of the AC component is the magnitude of the current vector, and the phase of the AC component is the direction angle of the current vector. Therefore, when all battery clusters are at the same temperature, the magnitudes of the current vectors applied to heating are equal for all battery clusters. To ensure that the vector sum of the AC components corresponding to all battery clusters is zero, after phase allocation, the corresponding current vectors of all AC components can be connected end-to-end to form a regular polygon.

[0044] Understandably, based on the regular polygon constructed from the current vectors corresponding to the aforementioned n battery clusters, this regular polygon can be uniformly distributed on the circumcircle. Taking the line connecting one point on the circumcircle to the center as the baseline, the angles between the lines connecting all points on the circumcircle to the center and the baseline are: 0, 2π / n, 4π / n, ..., 2π(n-1) / n. Therefore, the general term 2π(k-1) / n of the angle corresponding to any point k on the circumcircle is the phase assigned to the AC component corresponding to battery cluster k. The value of .

[0045] Second, regarding the situation where there are inconsistent temperature states among all battery clusters.

[0046] In this embodiment, based on the different temperature states of each battery cluster, an amplitude matching algorithm can be further constructed on the basis of phase planning to achieve a power cancellation method of "phase misalignment + amplitude reconstruction". The phase allocation of the AC components corresponding to each battery cluster includes the following process: determining the amplitude of the AC component required for heating each battery cluster according to the temperature of each battery cluster; equalizing the amplitude of each determined AC component, and calculating the phase of each AC component according to the equalized amplitude, so that the vector sum of all AC components is zero.

[0047] It is understood that the core of the technical solution in this application is: by flexibly configuring the phase difference and different amplitudes of the heating currents of multiple battery clusters, the heating currents of all battery clusters are made to satisfy the vector sum of zero; thus, while still achieving system-level power stability and constant bus voltage, the different heating power requirements of different battery clusters at different temperatures are met. In other words, by independently configuring the amplitude and phase of the AC components among each battery cluster, each battery cluster can be heated differently according to temperature differences without affecting the overall system operation.

[0048] To facilitate understanding, a simple example can be used. Assume there are three battery clusters, one of which has a significantly lower temperature than the other two. This lower cluster requires a higher heating power. Therefore, the amplitude of the AC component corresponding to the lowest-temperature battery cluster can be set as A0, and its phase can be defined as... Then the amplitude of the AC component corresponding to the other two battery clusters can be set to A0 / 2, and the phase of the AC component corresponding to these two battery clusters can be assigned as follows: +180°, thus the combined waveform of the heating current of the three battery clusters can be equivalently canceled out. As can be seen from the above, the amplitude of the AC component is determined by the heating demand of the battery cluster, while the phase of the AC component is determined by the vector sum of the AC components of all battery clusters being zero; the calculation process of phase shift of the AC component based on amplitude equalization distribution will be described in detail below.

[0049] In this embodiment, as Figure 3 As shown, the calculation process for phase shift based on the equalization distribution of the amplitudes of each AC component is as follows: The amplitudes of the AC components corresponding to all battery clusters are summed to obtain the amplitude sum S; the maximum amplitude A of the AC components corresponding to all battery clusters is marked. max If there are two battery clusters, the amplitude of the AC components corresponding to the two battery clusters is evenly distributed so that both take the maximum amplitude A. max Simultaneously, the AC components corresponding to the two battery clusters are out of phase, i.e., the phase difference is 180°; therefore, the current vectors constructed by the AC components corresponding to the two battery clusters have the same magnitude and opposite directions. Consequently, the two current vectors can cancel each other out during synthesis, achieving battery cluster heating while avoiding system power disturbances. If the number of battery clusters exceeds two, according to A... max with SA max The relationship between the components is determined by using a grouped vector synthesis algorithm to determine the phase of the AC component corresponding to each battery cluster.

[0050] It is understandable that for the maximum amplitude A max with SA max The main relationship between them is: A max ≥SA max , or Amax <SA max For A max ≥SA max From the perspective of current vector, the maximum amplitude A max The magnitude of the corresponding current vector is greater than or equal to the sum of the magnitudes of the current vectors corresponding to the other magnitudes. For A max <SA max From the perspective of current vector, the maximum amplitude A max The magnitude of the corresponding current vector is less than the sum of the magnitudes of the current vectors corresponding to the other magnitudes. Based on the above analysis, the following will focus on the maximum magnitude A. max with SA max The specific relationships between them are described in detail, and the specific working process of the group vector synthesis algorithm is described in detail.

[0051] In this embodiment, as Figure 3 As shown, when the number of battery clusters n > 2, and A max ≥SA max At that time, the working process of the group vector synthesis algorithm is as follows: the maximum amplitude A is... max The corresponding battery clusters are designated as the first group, while the remaining battery clusters are designated as the second group; keeping the amplitude of the battery clusters in the first group unchanged, the amplitude of the AC component corresponding to each battery cluster in the second group is increased by (2A). max -S) / (n-1); At the same time, the phase of the AC component corresponding to the second group of battery clusters is set to be in phase and out of phase with the phase of the AC component corresponding to the first group of battery clusters.

[0052] It is understandable that when A max =SA max When, it indicates the maximum amplitude A max The magnitude of the corresponding current vector is exactly equal to the sum of the magnitudes of the current vectors corresponding to the other magnitudes; at this time (2A) max The value of -S) / (n-1) is 0, meaning the amplitude of the AC component corresponding to each battery cluster in the second group remains unchanged. Therefore, it is only necessary to adjust the phase of the AC component corresponding to the battery cluster in the second group relative to the largest amplitude A in the first group. max If the phases of the corresponding AC components are reversed, then the current vectors corresponding to all AC components can cancel each other out by vector composition. When A max >SA maxAs the previous analysis showed, due to the mismatch in magnitude of the current vectors corresponding to the first and second battery clusters, no matter how the phase of the AC component corresponding to the second battery cluster was adjusted, the vector sum could not be zero; that is, the prerequisite for achieving a zero vector sum is that the total magnitude of the current vectors corresponding to the two battery clusters must be equal. Therefore, it is necessary to increase the amplitude of the AC component corresponding to the second battery cluster, and the amount of amplitude increase... =(2A max -S) / (n-1). For ease of understanding, the following will explain the increase in amplitude. The derivation process will be described briefly.

[0053] Specifically, before the increase was made, the sum of the amplitudes of the AC components corresponding to the second group of battery clusters was SA. max After the amplitude was increased, the amplitude of the AC component corresponding to each battery cluster in the second group increased. Then, at this time, the sum of the amplitudes of the AC components corresponding to the second group of battery clusters is (SA). max )+(n-1) To ensure that the current vectors corresponding to the two battery clusters can cancel each other out, it is necessary to ensure that the sum of the amplitudes of the AC components corresponding to the two battery clusters are equal, that is: (SA max )+(n-1) = A max Solving this expression yields... =(2A max -S) / (n-1).

[0054] In this embodiment, when the number of battery clusters n > 2, and A max <SA max In this case, the battery cluster with the largest amplitude can be combined with several other battery clusters to form the first group, and then the remaining battery clusters can be combined to form the second group. When constructing these two groups of battery clusters, it is only necessary to ensure that the sum of the amplitudes of the AC components corresponding to the two groups of battery clusters are equal. In this way, vector cancellation can be achieved by simply inverting the phases of the AC components corresponding to the two groups of battery clusters, thus completing the working process of the grouped vector synthesis algorithm.

[0055] It's important to know that, typically, it's rare for the sum of the amplitudes of the AC components corresponding to the two battery clusters to be exactly equal. Therefore, to ensure that the two battery clusters can achieve vector cancellation, refer to A. max ≥SA maxIn this case, the amplitude of the AC component corresponding to one of the battery clusters is adjusted, i.e., increased or decreased by a given amplitude increment. However, those skilled in the art should know that adjusting the amplitude of the AC component corresponding to the battery cluster will cause the final heating temperature of the battery cluster to deviate slightly from the theoretical optimal temperature, which may have a certain impact on the actual operation of the battery cluster.

[0056] According to the triangle inequality, for any three sides, as long as the longest side is less than the sum of the other two sides, these three sides will always form a triangle; therefore, in triangle A... max <SA max In this case, the current vector corresponding to the battery cluster with the largest amplitude and the current vectors corresponding to the other battery clusters can definitely be used to construct a vector triangle that can achieve vector cancellation through phase adjustment. Therefore, in this embodiment, for A max <SA max In this case, the vector sum of all AC components can be made zero simply by adjusting the phase of the AC components corresponding to the battery cluster, without adjusting the amplitude of the AC components corresponding to the battery cluster.

[0057] Specifically, such as Figure 3 As shown, when the number of battery clusters n > 2, and A max <SA max The working process of the grouped vector synthesis algorithm is as follows: all battery clusters are divided into three groups, the phases of the AC components corresponding to the battery clusters in each group are the same, and the sum of the amplitudes of the AC components corresponding to the three groups satisfies the triangle relationship; taking the phase of the AC component corresponding to one group of battery clusters as the reference, the phases of the AC components corresponding to the other two groups of battery clusters are calculated by using the cosine theorem.

[0058] It should be noted that for A max <SA max In cases where the working process of the grouped vector synthesis algorithm can be completed by grouping two battery clusters, the grouping of two battery clusters should be preferred. Compared with the grouping of three battery clusters, the grouping of two battery clusters can simplify the subsequent phase allocation process of the AC components.

[0059] Those skilled in the art should know that when grouping battery clusters, the sum of the amplitudes of the AC components corresponding to the three battery clusters can theoretically form triangles of any shape, provided that the triangle's sides are satisfied. Although the vector sum of the AC components corresponding to the three battery clusters can be zero at this point, extreme phase angles may lead to a decrease in the phase allocation accuracy of the AC components, such as extreme scenarios with phase angles of 179° or 1°. Therefore, in this embodiment, when grouping battery clusters, it should be ensured that the sum of the amplitudes of the AC components corresponding to the three battery clusters tends to be consistent, i.e., the constructed triangle tends to be an equilateral triangle. This ensures that the amplitudes of the three total current vectors obtained by iterating through the corresponding current vectors of the three battery clusters tend to be consistent, and the phase difference tends to be 120°, achieving zero vector synthesis while ensuring pure harmonic content. For ease of understanding, the specific grouping process of the battery clusters will be described in detail below.

[0060] In this embodiment, as Figure 3 As shown, when the number of battery clusters n > 2, and A max <SA max The specific process of grouping all battery clusters into three groups is as follows: First, the amplitudes A1~A1 of the AC components corresponding to each of the n battery clusters can be determined. n Sort the values ​​from smallest to largest, and the resulting amplitudes are B1 to B. n Take the maximum amplitude A. max =B n As the target amplitude K=B n It then determines whether the target amplitude K is greater than or equal to S / 3; if the target amplitude K is greater than or equal to S / 3, the battery cluster corresponding to the target amplitude K is designated as the first group; if the target amplitude K is less than S / 3, the current minimum amplitude A is removed. min =B1 is added to the target amplitude K to perform the target amplitude update process, that is, adding the smallest amplitude that has not been added among all amplitudes to obtain the updated target amplitude K=B n +B1. After each update of the target amplitude K, determine whether the target amplitude K is greater than or equal to S / 3; if the target amplitude K is still less than S / 3, repeat the above target amplitude K update process until the target amplitude K is greater than or equal to S / 3. At this time, the target amplitude K can be expressed as K=B n +B1+……+B i Let i = {2, 3, ...}. Determine if the target amplitude K is less than S / 2. If it is, take all battery clusters corresponding to the amplitudes in target amplitude K as the first group; otherwise, take the minimum amplitude B accumulated at the end of target amplitude K. i The battery clusters corresponding to the remaining amplitude after return are designated as the first group.

[0061] From the remaining AC components corresponding to the battery clusters, a new target amplitude is selected and the above process is repeated to obtain the second group of battery clusters; that is, the current maximum amplitude A is selected. max =B n-1 As the target amplitude K=B n-1 It then determines whether the target amplitude K is greater than or equal to S / 3; if the target amplitude K is greater than or equal to S / 3, the battery cluster corresponding to the target amplitude K is designated as the second group; if the target amplitude K is less than S / 3, the current minimum amplitude A is removed. min =B j Add the target amplitude K to perform the target amplitude update process, which involves adding the smallest amplitude that has not been added among all amplitudes, to obtain the updated target amplitude K=B. n-1 +B j After each update of the target amplitude K, it is determined whether the target amplitude K is greater than or equal to S / 3. If the target amplitude K is still less than S / 3, the above target amplitude K update process is repeated until the target amplitude K is greater than or equal to S / 3. Then, it is determined whether the target amplitude K is less than S / 2. If the target amplitude K is less than S / 2, all battery clusters corresponding to the amplitudes of the target amplitude K are designated as the second group; otherwise, the battery clusters corresponding to the remaining amplitudes after the minimum amplitude of the last accumulated target amplitude K is returned are designated as the second group. After constructing the battery clusters of the first and second groups, the remaining battery clusters are designated as the third group.

[0062] In this embodiment, the entire control loop of the energy storage system includes a PV control loop, a battery control loop, and a DC / AC control loop. The PV control loop controls the DC / DC circuit on the PV side to perform MPPT tracking, and the DC / AC control loop controls the DC / AC circuit on the AC side to control the grid-connected current while achieving bus voltage balance. The battery control loop controls the bidirectional DC / DC circuit based on the heating current command of the battery cluster generated by the current reference after phase allocation.

[0063] It should be noted that the specific working methods of the PV control loop and DC / AC control loop are the same as those of the traditional method, so they will not be elaborated here. The specific process of the battery control loop controlling the bidirectional DC / DC circuit will be described below.

[0064] Specifically, such as Figure 4 As shown, the specific control of the bidirectional DC / DC circuit includes the following process: Selecting the heating current frequency within the bandwidth of the current loop PI controller to ensure that the current loop PI controller can track the given target value with almost zero error; sampling the current, voltage, and battery temperature output by the battery cluster, respectively I... bat U bat , T.

[0065] Based on the collected battery temperature T, the amplitude A and phase of the AC component corresponding to each battery cluster can be calculated using an amplitude / phase allocation algorithm. After determining the amplitude A and phase of the AC component... Then, substituting this into the expression for the current reference, we can obtain the corresponding heating current command I=Asin(ω·t+ Then input the information.

[0066] According to the power command P of the battery cluster ref With the sampled output voltage U bat The current command value I is calculated. ref The calculated current command value I ref After being superimposed with the input heating current command I, and then with the sampled output current I... bat Perform a difference comparison; send the difference to the PI controller to generate the duty cycle, and then control the PWM generator to generate the drive signal to control the bidirectional DC / DC circuit.

[0067] To facilitate understanding, the following will take an energy storage system consisting of three battery clusters as an example to describe in detail the specific working process of the battery control loop.

[0068] like Figure 4 As shown, the three battery clusters of the energy storage system are labeled Bat#1 to Bat#3, and the collected data for each of the three battery clusters are as follows: (I bat-1 U bat-1 ,T1) 、(I bat-2 U bat-2 , T2) and (I bat-3 U bat-3 Based on the temperatures T1 to T3 corresponding to the three battery clusters, the amplitude A and phase of the AC component corresponding to each of the three battery clusters can be calculated using an amplitude / phase allocation algorithm. They are respectively labeled as (A1, (A2, ) and (A2, Based on the obtained amplitude A and phase It can generate heating current commands corresponding to three battery clusters, each labeled as I. h-1 I h-2 and I h-3 .

[0069] For the bidirectional DC / DC circuit corresponding to battery cluster Bat#1, the power command P of battery cluster Bat#1 can be used. ref-1 With the sampled output voltage U bat-1 The current command value I is calculated. ref-1 The calculated current command value Iref-1 With input heating current command I h-1 After superposition, it is compared with the sampled output current I. bat-1 Perform a difference comparison; send the difference to the PI controller to generate the duty cycle, and then control the PWM generator to generate the drive signal to control the bidirectional DC / DC#1.

[0070] For the bidirectional DC / DC circuit corresponding to battery cluster Bat#2, the power command P of battery cluster Bat#2 can be used. ref-2 With the sampled output voltage U bat-2 The current command value I is calculated. ref-2 The calculated current command value I ref-2 With input heating current command I h-2 After superposition, it is compared with the sampled output current I. bat-2 Perform a difference comparison; send the difference value to the PI controller to generate the duty cycle, which in turn controls the PWM generator to generate the drive signal to control the bidirectional DC / DC#2.

[0071] For the bidirectional DC / DC circuit corresponding to battery cluster Bat#3, the power command P of battery cluster Bat#3 can be used. ref-3 With the sampled output voltage U bat-3 The current command value I is calculated. ref-3 The calculated current command value I ref-3 With input heating current command I h-3 After superposition, it is compared with the sampled output current I. bat-3 Perform a difference comparison; send the difference to the PI controller to generate the duty cycle, and then control the PWM generator to generate the drive signal to control the bidirectional DC / DC#3.

[0072] It should be noted that the battery control loop is not limited to the above embodiments. It can also modulate the corresponding AC component based on the temperature of the battery cluster to obtain a first duty cycle for heating the battery cluster. Then, this first duty cycle is superimposed with the duty cycle generated by the normal current loop to control the corresponding bidirectional DC / DC circuit. That is, the battery control loop includes two current loops: one for controlling battery cluster heating and the other for controlling normal charging and discharging of the battery cluster. The two current loops generate different duty cycles based on different inputs, and finally, the duty cycles output by the two current loops are superimposed for the final control of the bidirectional DC / DC circuit.

[0073] Another aspect of this application provides an electronic device, in one preferred embodiment of which includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the above-described energy storage battery heating method.

[0074] Another aspect of this application provides a computer-readable storage medium, in a preferred embodiment of which a computer program is stored on the storage medium; when the computer program is executed by a processor, the above-described energy storage battery heating method is implemented.

[0075] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method for heating an energy storage battery, applied to a topology in which multiple battery clusters are connected via a common DC bus through corresponding bidirectional DC / DC circuits, characterized in that, Includes the following steps: A current reference for the battery cluster is constructed, the current reference including a DC component and an AC component; wherein, the DC component is used to maintain the charging and discharging of the battery cluster, and the AC component is used to control the heating of the battery cluster; Based on the different temperature states of each battery cluster, the phase allocation of the AC component corresponding to each battery cluster includes the following process: determining the amplitude of the AC component required for heating each battery cluster according to the temperature of each battery cluster; uniformly distributing the determined amplitude of each AC component, and calculating the phase of each AC component according to the uniformly distributed amplitude, so that the vector sum of all AC components is zero. Based on the current reference after phase allocation, a heating current command for the battery cluster is generated and input to the corresponding bidirectional DC / DC circuit; The calculation process for phase shift based on the amplitude equalization distribution of each AC component is as follows: The amplitudes of the AC components corresponding to all the battery clusters are summed to obtain the amplitude sum S; Mark the maximum amplitude A of the AC component corresponding to all the battery clusters. max ; The number of battery clusters, n > 2, according to A max with SA max The relationship between the battery clusters is determined by using a grouped vector synthesis algorithm to determine the phase of the AC component corresponding to each battery cluster. In A max ≥SA max The working process of the group vector synthesis algorithm is as follows: The maximum amplitude A max The corresponding battery clusters are designated as the first group, while the remaining battery clusters are designated as the second group; Keeping the amplitude of the battery clusters in the first group unchanged, the amplitude of the AC component corresponding to each battery cluster in the second group is increased by (2A). max -S) / (n-1); The phase of the AC component corresponding to the battery cluster in the second group is set to be in phase and out of phase with the phase of the AC component corresponding to the battery cluster in the first group; In A max <SA max The working process of the group vector synthesis algorithm is as follows: among the amplitudes of the AC components corresponding to all the battery clusters, several remaining amplitudes are added to the largest amplitude and then summed. If the sum of the summed amplitudes is equal to the sum of the remaining amplitudes, the battery clusters corresponding to the summed amplitudes are taken as the first group, and the remaining battery clusters are taken as the second group. The phases of the AC components corresponding to each group of battery clusters are the same, and the phases of the AC components corresponding to the two groups of battery clusters are out of phase. Alternatively, all the battery clusters can be divided into three groups, with the AC components corresponding to the battery clusters in each group having the same phase, and the sum of the amplitudes of the AC components corresponding to the three groups satisfying the triangle relationship; using the phase of the AC component corresponding to one group of battery clusters as a reference, the phases of the AC components corresponding to the other two groups of battery clusters can be calculated using the cosine theorem.

2. The energy storage battery heating method as described in claim 1, characterized in that, For the scenario where all battery clusters are divided into three groups, the specific grouping process for all battery clusters is as follows: Take the maximum amplitude A max The target amplitude is used as the target amplitude, and it is determined whether the target amplitude is greater than or equal to S / 3; if the target amplitude is greater than or equal to S / 3, the battery cluster corresponding to the target amplitude is taken as the first group; If the target amplitude is less than S / 3, the current minimum amplitude A will be... min Add it to the target amplitude to perform the target amplitude update process; After each update of the target amplitude, determine whether the target amplitude is greater than or equal to S / 3; If the target amplitude is still less than S / 3, repeat the target amplitude update process above until the target amplitude is greater than or equal to S / 3. Determine whether the target amplitude is less than S / 2. If the target amplitude is less than S / 2, take the battery clusters corresponding to all amplitudes in the target amplitude as the first group; otherwise, take the battery clusters corresponding to the remaining amplitudes after returning the minimum amplitude of the last accumulated target amplitude as the first group. From the remaining AC components corresponding to the battery clusters, a target amplitude is reselected and the above process is repeated to obtain the second group of battery clusters; After the construction of the first and second groups of battery clusters is completed, the remaining battery clusters are designated as the third group.

3. The energy storage battery heating method as described in claim 1 or 2, characterized in that, The specific control of the bidirectional DC / DC circuit includes the following process: The output voltage and current of each battery cluster, as well as the battery temperature, are sampled. The heating current command corresponding to each battery cluster is determined based on the collected battery temperature and then input. The current command value is calculated based on the power command of the battery cluster and the sampled output voltage; The calculated current command value is superimposed with the input heating current command, and then compared with the sampled output current. The difference is fed into the PI controller to generate the duty cycle, which in turn controls the PWM generator to generate the drive signal for controlling the bidirectional DC / DC circuit.

4. An electronic device, characterized in that, It includes a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program to implement the energy storage battery heating method as described in any one of claims 1-3.

5. A computer-readable storage medium, characterized in that, The storage medium stores a computer program; when the computer program is executed by a processor, it implements the energy storage battery heating method as described in any one of claims 1-3.

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