Energy storage system current detection method, device and storage medium

Abstract

The application relates to a current detection method and device of an energy storage system and a storage medium, and belongs to the technical field of energy storage. The method comprises the following steps: acquiring a current no-load mode and a sampling current of a target battery to be detected in an energy storage system; acquiring a current correction coefficient corresponding to the current no-load mode; in the case that the sampling current belongs to a first data range, correcting the sampling current based on the current correction coefficient to obtain a corrected current; the method can solve the problem that a traditional current detection method uses a fixed compensation method for current compensation, and the result of the compensated current is inaccurate. Since different no-load modes correspond to different current correction coefficients, the sampling current is corrected using the current correction coefficient corresponding to the current no-load mode, so that the current correction coefficient can adapt to different no-load scenes of the energy storage system, and the accuracy of current correction is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to a current detection method and device of an energy storage system and a storage medium, and belongs to the technical field of energy storage. BACKGROUND

[0002] In an energy storage system, a battery management system (BMS) can determine the battery state in real time. In the process of determining the battery state, the current of the battery often needs to be detected by a sensor. For example, when estimating the state of charge (SOC) of the battery during discharging, the output current of the battery needs to be detected for integration to determine the SOC. However, when the current of the battery is very small, due to the limitations of sensor accuracy and the influence of system power consumption, there will be measurement errors in current detection, which will lead to inaccurate battery state determination.

[0003] In order to improve the accuracy of detecting the current of the battery in the energy storage system, the current detection method currently includes dividing the current data into multiple data ranges. For the sampled current in the data range with low confidence, the energy storage system no longer trusts the readings of the current sensing component, but relies on a high-precision voltage sensor to perform voltage sampling, and estimates the battery state by querying the relationship curve between the open circuit voltage (OCV) of the battery and the battery state (such as the state of charge (SOC) of the battery).

[0004] The relationship curve between the OCV and the battery state is usually nonlinear. In order to simplify the calculation, the energy storage system usually approximates the curve as a straight line in a small range around a certain battery state point. Then, according to the real-time measured voltage value, interpolation is performed on the "local straight line" to calculate the corresponding battery state. Further, in order to improve the estimation smoothness in the blind area, a fixed "compensation coefficient" is introduced to fine-tune the result of the ampere-hour integration method, so that it approaches the result estimated by the OCV method, and prevents error accumulation.

[0005] However, the compensated current obtained by the fixed compensation method may still have a large error. SUMMARY

[0006] The present application provides a current detection method and device of an energy storage system and a storage medium, which can solve the problem that the compensated current obtained by the fixed compensation method of the traditional current detection method is inaccurate. The present application provides the following technical solutions:

[0007] In a first aspect, a current detection method for an energy storage system is provided, the method comprising:

[0008] The current no-load mode and sampling current of the target battery to be tested in the energy storage system are obtained; the target battery includes at least two no-load modes.

[0009] Obtain the current correction coefficient corresponding to the current no-load mode; wherein, the current correction coefficient is used to correct the deviation between the theoretical no-load current and the actual no-load current corresponding to the current no-load mode;

[0010] If the sampled current falls within the first data range, the sampled current is corrected based on the current correction coefficient to obtain the corrected current.

[0011] Optionally, after correcting the sampled current based on the current correction coefficient to obtain the corrected current, the method further includes:

[0012] If the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode, the load current is determined based on the difference between the corrected current and the theoretical no-load current, so as to determine the battery state of the target battery based on the load current; wherein, the current correction coefficient is used to correct the deviation between the theoretical no-load current and the actual no-load current.

[0013] Optionally, obtaining the current correction coefficient corresponding to the current no-load mode includes:

[0014] The current correction coefficient is obtained by determining the ratio of the theoretical no-load current corresponding to the current no-load mode to the actual no-load current value under no-load conditions.

[0015] Optionally, obtaining the current correction coefficient corresponding to the current no-load mode includes:

[0016] In at least one of the at least two no-load modes other than the current no-load mode, obtain the no-load power of m other no-load modes in the no-load state; m is a positive integer.

[0017] Based on the similarity between the idle power corresponding to each of the m other idle modes and the idle power corresponding to the current idle mode, the coefficient adjustment weight of each other idle mode relative to the current idle mode is determined.

[0018] Determine the ratio of the theoretical no-load current to the actual no-load current value under no-load conditions for each other no-load mode.

[0019] Determine a weighted sum value of the coefficient adjustment weight corresponding to each of the m other idle modes and the current ratio of the current, to obtain the current correction coefficient.

[0020] Optionally, the coefficient adjustment weight of each of the m other idle modes relative to the current idle mode is determined based on a similarity between the idle power corresponding to each of the m other idle modes and the idle power corresponding to the current idle mode, including:

[0021] For each of the m other idle modes, determine an absolute value of a difference between the idle power corresponding to the other idle mode and the idle power corresponding to the current idle mode;

[0022] Determine the coefficient adjustment weight based on an inverse of a sum of the absolute value of the difference and a preset value.

[0023] Optionally, the coefficient adjustment weight is determined based on the inverse of the sum of the absolute value of the difference and the preset value, including:

[0024] Based on a sum of inverses corresponding to the m other idle modes, normalize the inverse corresponding to each of the other idle modes to obtain the coefficient adjustment weight corresponding to each of the other idle modes.

[0025] Optionally, the method further includes:

[0026] In a case where the sampling current belongs to a second data range, determine the corrected current as the theoretical idle current;

[0027] In a case where the sampling current belongs to a third data range, determine the corrected current as the sampling current;

[0028] Each value in the second data range is less than a minimum value of the first data range, and each value in the third data range is greater than a maximum value of the first data range.

[0029] Optionally, the at least two idle modes include at least one of the following:

[0030] The first idle mode refers to a state in which a DC circuit in the energy storage system is turned on, an AC circuit in the energy storage system is turned off, and the energy storage system is not connected to a load;

[0031] The second idle mode refers to a state in which the AC circuit in the energy storage system is turned on, the DC circuit in the energy storage system is turned off, and the energy storage system is not connected to the load;

[0032] The third idle mode refers to a state in which the AC circuit in the energy storage system is turned on, the DC circuit in the energy storage system is turned on, and the energy storage system is not connected to the load;

[0033] The fourth no-load mode refers to a state that the AC circuit and the DC circuit in the energy storage system are closed, and the energy storage system is not connected to a load.

[0034] In a second aspect, a current detection device of an energy storage system is provided, and the device includes a processor and a memory. The memory stores a program, which is loaded and executed by the processor to implement the current detection method of the energy storage system in the first aspect.

[0035] In a third aspect, a computer-readable storage medium is provided, and the storage medium stores a program, which is loaded and executed by the processor to implement the current detection method of the energy storage system in the first aspect.

[0036] The application has the beneficial effect that: the current no-load mode and the sampling current of the target battery to be detected in the energy storage system are obtained; the current correction coefficient corresponding to the current no-load mode is obtained; in the case that the sampling current belongs to the first data range, the sampling current is corrected based on the current correction coefficient to obtain the corrected current; the problem that the traditional current detection method uses a fixed compensation method for current compensation, and the result of the compensated current is inaccurate can be solved. Since different current correction coefficients correspond to different no-load modes, the sampling current is corrected using the current correction coefficient corresponding to the current no-load mode, which can ensure that the current correction coefficient can adapt to different no-load scenarios of the energy storage system and ensure the accuracy of current correction.

[0037] The above description is only a summary of the technical solutions of the application. In order to more clearly understand the technical means of the application, and to implement the content of the description, the following will be described in detail with the preferred embodiments of the application and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 FIG. 1 is a schematic diagram of a current detection device of an energy storage system according to an embodiment of the application;

[0039] Figure 2 FIG. 2 is a flowchart of a current detection method of an energy storage system according to an embodiment of the application;

[0040] Figure 3 FIG. 3 is a flowchart of a current detection method of an energy storage system according to another embodiment of the application;

[0041] Figure 4 FIG. 4 is a block diagram of a current detection device of an energy storage system according to an embodiment of the application;

[0042] Figure 5 FIG. 5 is a block diagram of a current detection device of an energy storage system according to an embodiment of the application. DETAILED DESCRIPTION

[0043] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0044] Figure 1 is a schematic diagram of a current detection device of an energy storage system provided by an embodiment of the present application. The energy storage system comprises: a battery module, a direct current (DC) circuit connected to the battery module, an inverter circuit connected to the DC circuit, and an alternating current (AC) circuit connected to the inverter circuit, the AC circuit being used to connect to a power grid or a load. The battery module comprises at least one battery, and in the case where the battery module comprises a plurality of batteries, the plurality of batteries can form at least one battery cluster, and the number of batteries in the battery module and the form of energy storage are not limited by the embodiment. The DC circuit is used to provide a stable DC bus voltage for the inverter circuit, the inverter circuit is used to perform AC / DC conversion between the DC circuit and the AC circuit, and the AC circuit is used to convert the output of the inverter circuit into the required power of the power grid or the load.

[0045] As shown in Figure 1 , the current detection device of the energy storage system comprises: a sensor assembly 110 and a processing assembly 120 connected in communication with the sensor assembly.

[0046] The sensor assembly 110 is at least used to collect an electrical parameter of each target battery to be detected in the energy storage system, and the electrical parameter includes but is not limited to: a battery voltage of the target battery (i.e., an end voltage of the target battery), and a sampling current of the target battery (i.e., an output current of the target battery); accordingly, the sensor assembly 110 comprises a voltage sensing assembly 111 for collecting the battery voltage, and a current sensing assembly 112 for collecting the sampling current.

[0047] Optionally, the sensor assembly 110 can further comprise a temperature sensor for collecting a battery temperature of the target battery.

[0048] Optionally, the target battery can be each battery in the energy storage system, or can also be part of the batteries in the energy storage system, and the implementation manner of the target battery is not limited by the embodiment.

[0049] The processing assembly 120 can be a battery management system (BMS) in the energy storage system, or can also be a device with processing capability independent of the BMS, and the implementation manner of the processing assembly 120 is not limited by the embodiment.

[0050] In this embodiment, the processing component 120 can obtain the sampling current collected by the current sensing component 112 and the battery voltage collected by the voltage sensing component 111. Accordingly, the processing component 120 is configured to perform the following steps of the current detection method of the energy storage system:

[0051] obtain a current no-load mode and a sampling current of a target battery to be detected in the energy storage system, obtain a current correction coefficient corresponding to the current no-load mode, and correct the sampling current based on the current correction coefficient to obtain a corrected current in a case where the sampling current belongs to a first data range.

[0052] The target battery includes at least two no-load modes, and the current correction coefficient is used to correct the deviation between the theoretical no-load current and the actual no-load current.

[0053] In the following, the current detection method of the energy storage system is described in detail.

[0054] Figure 2 is a flowchart of the current detection method of the energy storage system provided by an embodiment of the present application. This embodiment takes the processing component 120 in the current detection shown in FIG. 1 as an example to illustrate the method. The method includes at least the following steps: Figure 1

[0055] Step 201: Obtain a current no-load mode and a sampling current of a target battery to be detected in the energy storage system.

[0056] The target battery includes at least two no-load modes. The no-load mode (or standby state) refers to the state of the energy storage system when it is not connected to a load and not charging. Different no-load modes refer to different physical states of the energy storage system when it is not connected to a load and not charging.

[0057] In one example, the physical state includes the open and closed states of the AC circuit and the open and closed states of the DC circuit. Accordingly, the at least two no-load modes include at least one of the following:

[0058] The first no-load mode refers to the state of the energy storage system when the DC circuit is open, the AC circuit is closed, and the energy storage system is not connected to a load.

[0059] The second no-load mode refers to the state of the energy storage system when the AC circuit is open, the DC circuit is closed, and the energy storage system is not connected to a load.

[0060] The third no-load mode refers to the state of the energy storage system when the AC circuit is open, the DC circuit is open, and the energy storage system is not connected to a load.

[0061] The fourth no-load mode refers to the state of the energy storage system when the AC circuit is closed, the DC circuit is closed, and the energy storage system is not connected to a load.​

[0062] In other embodiments, the physical state includes: battery temperature, open and closed state of AC circuit, and open and closed state of DC circuit. Accordingly, at least two idle modes can also be divided in combination with battery temperature, open and closed state of AC circuit, and open and closed state of DC circuit. For example, a fifth idle mode refers to a state that the energy storage system is in the first temperature range, the DC circuit is open, the AC circuit is closed, and the energy storage system is not connected to the load; a sixth idle mode refers to a state that the energy storage system is in the second temperature range, the DC circuit is open, the AC circuit is closed, and the energy storage system is not connected to the load, and so on. The number of temperature ranges and the division method of idle modes are not limited in the embodiment.

[0063] The processing component obtains the physical state of the target battery in real time, and determines the current idle mode corresponding to the physical state. Taking at least two idle modes including a first idle mode, a second idle mode, a third idle mode, and a fourth idle mode as an example, the processing component can obtain the switch state of the switch in the AC circuit and the DC circuit, determine whether the AC circuit and the DC circuit are open based on the switch state, and determine the current idle mode corresponding to the switch state based on the switch state of the AC circuit and the DC circuit.

[0064] If the physical state further includes the battery temperature, the processing component can obtain the battery temperature collected by the temperature sensor, the switch state of the switch in the AC circuit and the DC circuit, determine whether the AC circuit and the DC circuit are open based on the switch state, and determine the current idle mode corresponding to the switch state based on the switch state of the AC circuit and the DC circuit and the battery temperature.

[0065] Optionally, the processing component obtains the sampling current, including: obtaining the current data collected by the current sensing component at the current collection time, to obtain the sampling current.

[0066] Alternatively, the processing component obtains the sampling current, including: obtaining the current data collected by the current sensing component at the current collection time and at N-1 continuous collection times between the current collection time, determining the average value of the current data at the N collection times, to obtain the sampling current. Accordingly, the sampling current can be represented by the following formula:

[0067] ;

[0068] In the formula, SamplingCurr(t) represents the current data at each of the continuous N collection times; SamplingCurr represents the sampling current determined based on the current data at the continuous N collection times.

[0069] Optionally, the processing component can synchronously acquire the current no-load mode and the sampling current, or asynchronously acquire the current no-load mode and the sampling current. The present embodiment does not limit the timing of the processing component acquiring the current no-load mode and the sampling current.

[0070] At step 202, the current no-load mode corresponding current correction coefficient is acquired.

[0071] The current correction coefficient is used to correct the deviation between the theoretical no-load current corresponding to the current no-load mode and the actual no-load current. The theoretical no-load current is determined based on the no-load power corresponding to the current no-load mode and the battery voltage in the no-load state. Specifically, the processing component acquires the no-load power, the battery voltage and the actual no-load current in the no-load state when the energy storage system is in the no-load state in the current no-load mode, determines the ratio of the no-load power to the battery voltage, and obtains the theoretical no-load current.

[0072] The no-load power of each control mode in the no-load state is obtained in the design stage of the target battery, and the no-load power is pre-stored in the storage medium of the electronic device. Accordingly, the no-load power in the no-load state is acquired by reading the no-load power of the current no-load mode in the no-load state stored in the storage medium. The battery voltage and the actual no-load current are acquired by acquiring the battery voltage collected by the battery sensing component and the actual no-load current collected by the current sensing component.

[0073] For example, at least two no-load modes include a first no-load mode, a second no-load mode, a third no-load mode and a fourth no-load mode. If the battery voltage is 48V when the energy storage system is in the no-load state in each no-load mode, the no-load power P1=5W corresponding to the first no-load mode and the actual no-load current I1=0.08A; the no-load power P2=8W corresponding to the second no-load mode and the actual no-load current I2=0.129A; the no-load power P3=13W corresponding to the third no-load mode and the actual no-load current I3=0.209A; the no-load power P4=1W corresponding to the fourth no-load mode and the actual no-load current I4, at this time, the actual no-load current is less than the minimum value of the current value that can be collected by the current sensing component, therefore, the processing component collects invalid actual no-load current or the actual no-load current is 0; the theoretical no-load current corresponding to each no-load mode can be represented by the following formula:

[0074] ;

[0075] wherein, represents the theoretical no-load current corresponding to the i-th no-load mode, represents the no-load power corresponding to the i-th no-load mode, represents the battery voltage corresponding to the i-th no-load mode.

[0076] According to the above calculation formula of the theoretical no-load current, the theoretical no-load current corresponding to the first no-load mode is =5 / 48≈0.104A; the theoretical no-load current corresponding to the second no-load mode is =8 / 48≈0.167A; the theoretical no-load current corresponding to the third no-load mode is =13 / 48≈0.271A; and the theoretical no-load current corresponding to the fourth no-load mode is =1 / 48≈0.021A.

[0077] In this embodiment, the current correction coefficient is determined based on at least the no-load power corresponding to the current no-load mode.

[0078] In one example, the current correction coefficient is determined based on the ratio of the theoretical no-load current and the actual no-load current corresponding to the current no-load mode. Accordingly, the current correction coefficient corresponding to the current no-load mode is obtained, including:

[0079] determining the ratio of the theoretical no-load current corresponding to the current no-load mode divided by the actual no-load current value in the no-load state, to obtain the current correction coefficient. At this time, the current correction coefficient can be expressed as:

[0080] ;

[0081] wherein, represents the current correction coefficient corresponding to the i-th no-load mode, represents the theoretical no-load current corresponding to the i-th no-load mode, represents the actual no-load current corresponding to the i-th no-load mode, and i is a positive integer.

[0082] According to the above calculation formula of the current correction coefficient , the current correction coefficient corresponding to the first no-load mode is =0.104 / 0.08=1.3; the current correction coefficient corresponding to the second no-load mode is =0.167 / 0.129≈1.295; the current correction coefficient corresponding to the third no-load mode is =0.271 / 0.209≈1.297; and the current correction coefficient corresponding to the fourth no-load mode is invalid. At this time, the corresponding relationship between the no-load power, the theoretical no-load current, the actual no-load current, and the current correction coefficient corresponding to each no-load mode is shown in Table 1. Table 1:

[0083]

[0084] ​

[0085] In another example, the current no-load mode corresponds to a current correction coefficient determined based on a similarity between the no-load power of the current no-load mode and the no-load power of other no-load modes. The other no-load modes refer to m other no-load modes among at least one other no-load mode except the current no-load mode among at least two no-load modes; m is a positive integer. Optionally, the m other no-load modes can be all no-load modes among the at least one other no-load mode, or be other no-load modes among the at least one other no-load mode whose actual no-load current does not belong to a second data range, for example: assuming that the first no-load mode among the four no-load modes shown in Table 1 is the current no-load mode, the second no-load mode and the third no-load mode except the fourth no-load mode can be the m no-load modes. Each value in the second data range is less than the minimum value of the current value that can be collected by the current sensing component.

[0086] Correspondingly, obtaining the current correction coefficient corresponding to the current no-load mode comprises:

[0087] Among the at least one other no-load mode except the current no-load mode among the at least two no-load modes, obtaining the no-load power of m other no-load modes in the at least one other no-load mode in the no-load state; determining a coefficient adjustment weight of each other no-load mode relative to the current no-load mode based on a similarity between the no-load power corresponding to each other no-load mode among the m other no-load modes and the no-load power corresponding to the current no-load mode; determining a current ratio value of a theoretical no-load current corresponding to each other no-load mode divided by an actual no-load current value in the no-load state; and determining a weighted sum value of the coefficient adjustment weight and the current ratio value corresponding to the m other no-load modes to obtain the current correction coefficient.

[0088] In one example, determining the coefficient adjustment weight of each other no-load mode relative to the current no-load mode based on the similarity between the no-load power corresponding to each other no-load mode among the m other no-load modes and the no-load power corresponding to the current no-load mode comprises:

[0089] For each other no-load mode among the m other no-load modes, determining an absolute value of a difference between the no-load power corresponding to the other no-load mode and the no-load power corresponding to the current no-load mode; and determining the coefficient adjustment weight based on an inverse of a sum of the absolute value and a preset value.

[0090] Optionally, the processing component can directly take the inverse of the sum of the absolute value and the preset value as the coefficient adjustment weight, or can normalize the inverse and take the normalized value as the coefficient adjustment weight. If the inverse is normalized, determining the coefficient adjustment weight based on the inverse of the sum of the absolute value and the preset value comprises:

[0091] Based on the sum of the reciprocals corresponding to the m other no-load modes respectively, the reciprocal corresponding to each other no-load mode is normalized to obtain a coefficient adjustment weight corresponding to each other no-load mode.

[0092] Correspondingly, the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to each other no-load mode and the preset value can be expressed by the following formula:

[0093] ;

[0094] Wherein, represents the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the jth other no-load mode in the m other no-load modes and the preset value ε. represents the no-load power of the current no-load mode, represents the no-load power of the jth other no-load mode. The preset value ε is used to avoid the denominator being 0, and the value of ε can be a small number, such as 0.1. The embodiment does not limit the value of ε.

[0095] The coefficient adjustment weight can be expressed by the following formula:

[0096] ;

[0097] Wherein, represents the coefficient adjustment weight corresponding to the jth other no-load mode in the m other no-load modes, wherein, represents the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the jth other no-load mode in the m other no-load modes and the preset value.

[0098] At this time, the current correction coefficient can be expressed by the following formula:

[0099] ;

[0100] Wherein, represents the coefficient adjustment weight corresponding to the jth other no-load mode in the m other no-load modes; represents the current ratio of the theoretical no-load current corresponding to the jth other no-load mode divided by the actual no-load current value in the no-load state.

[0101] Still taking the example that the no-load modes include the first no-load mode, the second no-load mode, the third no-load mode and the fourth no-load mode, the no-load power, the theoretical no-load current, the actual no-load current and the current ratio (i.e. the current calibration coefficient in Table 1) corresponding to each no-load mode are shown in Table 1:

[0102] ​If the current no-load mode is the first no-load mode, the m other no-load modes are the second no-load mode and the third no-load mode, and correspondingly, the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the second no-load mode and the preset value and the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the third no-load mode and the preset value are:

[0103] ;

[0104] ;

[0105] After normalizing the above reciprocals, the coefficient adjustment weight corresponding to the second no-load mode and the coefficient adjustment weight corresponding to the third no-load mode are:

[0106] ;

[0107] Correspondingly, the current no-load mode corresponds to the current no-load mode is:

[0108] .

[0109] If the current no-load mode is the second no-load mode, the m other no-load modes are the first no-load mode and the third no-load mode, and correspondingly, the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the first no-load mode and the preset value and the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the third no-load mode and the preset value are: ;

[0110] After normalizing the above reciprocals, the coefficient adjustment weight corresponding to the first no-load mode and the coefficient adjustment weight corresponding to the third no-load mode are:

[0111] ;

[0112] Correspondingly, the current no-load mode corresponds to the current no-load mode is: .

[0113] If the current no-load mode is the third no-load mode, the m other no-load modes are the first no-load mode and the second no-load mode, and correspondingly, the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the first no-load mode and the preset value and the reciprocal of the sum of the absolute value of the difference of the no-load power corresponding to the second no-load mode and the preset value are:

[0114] ;

[0115] After normalizing the above inverses, the coefficient adjustment weight corresponding to the first no-load mode is obtained and the coefficient adjustment weight corresponding to the second no-load mode is obtained

[0116] ;

[0117] Correspondingly, the current correction coefficient corresponding to the current no-load mode is

[0118] .

[0119] According to the above embodiment, since the sampling current corresponding to the fourth no-load mode is invalid, the current correction coefficient corresponding to the fourth no-load mode is invalid, and the current correction coefficient is not calculated in the embodiment.

[0120] According to the above example, the current correction coefficients corresponding to the first no-load mode, the second no-load mode and the third no-load mode calculated by the two methods can be shown in Table 2. Among them, the original is the current correction coefficient determined based on the ratio of the theoretical no-load current to the actual no-load current of the current no-load mode shown in Table 1, and the weighted is the current correction coefficient determined based on the similarity between the no-load power of the current no-load mode and the no-load power of other no-load modes.

[0121] Table 2:

[0122]

[0123] Among them, the change amplitude is: the weighted minus the original divided by the original value.

[0124] According to Table 2, on the one hand, for the first no-load mode, the current correction coefficient decreases from 1.3 to 1.296, and the weighted smooths the possible positive deviation; for the second no-load mode, the current correction coefficient increases from 1.285 to 1.299, and the weighted compensates for the possible negative deviation; for the third no-load mode, the current correction coefficient basically remains stable, and the weighted verifies the reliability of the current correction coefficient. On the other hand, since the other no-load modes close to the no-load power of the current no-load mode correspond to the weighted ​​Larger, thus, can ensure the weighted more in line with the physical characteristics of the energy storage system, to ensure the weighted calculation accuracy. In another aspect, since the m other no-load modes are not actual no-load current belonging to the second data range, thus, can ensure that the actual no-load current belonging to the second data range does not participate in the weighted calculation, so that the weighted calculation is based on valid data, which can further ensure the calculation accuracy of the weighted In another aspect, since the original based on a single measurement of no-load power, the actual no-load current is determined, the value is greatly affected by random error, and the weighted can be calculated by combining the related data of multiple no-load modes, which can reduce the influence of random error and further ensure the calculation accuracy of the weighted .

[0125] It should be noted that the theoretical no-load current corresponding to the current correction coefficient is determined when the battery voltage is 48V in Table 1 and Table 2. In actual implementation, different battery voltages can correspond to a set of current correction coefficients as the battery voltage changes. The calculation principle of the current correction coefficient is referred to the above example, which is not described herein. Correspondingly, if each no-load mode corresponds to different current correction coefficients at different battery voltages, the processing assembly acquires the battery voltage of the target battery when collecting the sampling current, and acquires the current correction coefficient corresponding to the battery voltage and the current correction coefficient corresponding to the current correction coefficient.

[0126] Optionally, the control assembly stores the correspondence between the no-load mode and the current correction coefficient after calculating the current correction coefficient corresponding to each no-load mode, and then determines the current correction coefficient corresponding to the current no-load mode from the correspondence after acquiring the current no-load mode each time.

[0127] Step 203, in the case that the sampling current belongs to the first data range, correcting the sampling current based on the current correction coefficient to obtain the corrected current.

[0128] Wherein, correcting the sampling current based on the current correction coefficient to obtain the corrected current includes: multiplying the sampling current by the current correction coefficient to obtain the corrected current. Illustratively, the corrected current is expressed by the following formula:

[0129] ;

[0130] Wherein, represents the current correction coefficient of the i-th no-load mode (i.e. the current no-load mode), represents the sampling current.

[0131] Optionally, if the sampled current falls within the second data range, the corrected current is determined to be the theoretical no-load current, i.e. ,in, This indicates the corrected current. This represents the theoretical no-load current corresponding to the i-th no-load mode (i.e., the current no-load mode).

[0132] If the sampled current falls within the third data range, the corrected current is determined to be the sampled current, i.e., .

[0133] The data range is defined as follows: the first data range is the area where the current sensing component can collect current, but the collected current is not accurate enough (or the error range); the second data range is the area where the current sensing component cannot collect current (or the dead zone); and the third data range is the area where the current sensing component can collect current accurately (or the high confidence range). All values ​​in the second data range are less than the minimum value of the first data range; all values ​​in the third data range are greater than the maximum value of the first data range. For example, all values ​​in the second data range are less than the minimum current value that the current sensing component can collect, and all values ​​in the first data range are greater than or equal to that minimum value.

[0134] For example, the minimum current value that the current sensing component can collect is 0.05A. Correspondingly, the second data range is [0, 0.05)A; the first data range is [0.05, 1)A; and the third data range is [1, 1)A. max )A. Among them, I max The value is determined based on the maximum current that the current sensing component can measure; specifically, I max The current value is less than or equal to the maximum current value that the current sensing component can measure. In other embodiments, the first, second, and third data ranges can also be implemented in other ways. The specific division method is designed based on the current measurement capability of the current sensor. Within the measurement range consisting of the minimum to the maximum current value that the current sensor can measure, the sampling data with high confidence can be used directly, and the data range consisting of these high-confidence sampling data is the third data range; the sampling data with low confidence needs to be calibrated, and the data range consisting of these low-confidence sampling data is the first data range; for current values ​​less than the minimum value, the current sensor has no data, and these data constitute the second data range. In this case, the theoretical no-load current is used as the sampling data. This embodiment does not limit the division method of the first, second, and third data ranges.

[0135] In the embodiment, by setting different current correction coefficients for different no-load modes, the current correction coefficient corresponding to the current no-load mode is used to correct the sampling current, which can ensure that the current correction coefficient can adapt to different no-load scenarios of the energy storage system and ensure the accuracy of current correction.

[0136] In addition, in the case that the sampling current belongs to the first data range, it indicates that there is an error in the current collected by the current sensing component, which is similar to the error between the theoretical no-load current and the actual no-load current. Therefore, in the embodiment, the sampling current in the first data range is corrected by using the current correction coefficient, so that the corrected current basically conforms to the expected value. Based on the corrected current, the load current can be extracted, which can improve the accuracy of the load current.

[0137] In summary, the current detection method of the energy storage system provided in the embodiment can obtain the current no-load mode and the sampling current of the target battery to be detected in the energy storage system, obtain the current correction coefficient corresponding to the current no-load mode, and correct the sampling current based on the current correction coefficient in the case that the sampling current belongs to the first data range, to obtain the corrected current. The traditional current detection method uses a fixed compensation method for current compensation, and the result of the compensated current is inaccurate. Since different no-load modes correspond to different current correction coefficients, the current correction coefficient corresponding to the current no-load mode is used to correct the sampling current, which can ensure that the current correction coefficient can adapt to different no-load scenarios of the energy storage system and ensure the accuracy of current correction.

[0138] In addition, by combining the no-load power of other no-load modes to determine the current correction coefficient of the current no-load mode, the influence of random error can be reduced, the calculation accuracy of the current correction coefficient can be improved, and the detection accuracy of the load current and the estimation accuracy of the battery state can be further improved.

[0139] In addition, since the current that cannot be sampled by the current sensing component in the second data range can use the theoretical no-load current corresponding to the current no-load mode as the corrected current to estimate the battery state, the problem that the battery state estimation in the second data range is interrupted due to the inability of the current sensing component to sample the current can be avoided, and the continuity of the battery state estimation is ensured.

[0140] In the traditional current detection method, a small power load with a known resistance can be connected in parallel in the battery loop through a switch, and the current of the battery can be collected by a current sensor. When the collected current is less than a preset value (which can be the minimum value that can be detected by the current sensor), the switch is closed, and the loop where the small load is located is turned on. At this time, after the battery loop is connected to the small load, a stable small current loop is formed, and the current sensor can relatively accurately measure the known and stable current value.

[0141] However, the current value collected by the current sensor includes the system power consumption current and the load current, and only the load current is needed when determining the load power. If the two currents cannot be effectively separated, the estimation error of the load power will be large.

[0142] Optionally, based on the above problem, after step 203, further comprising: in a case where the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode, determining the load current based on a difference between the corrected current and the theoretical no-load current.

[0143] In a case where the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode, it indicates that the energy storage system accesses the load. At this time, the load current can be extracted by subtracting the theoretical no-load current from the corrected current. Exemplarily, the load current can be represented as:

[0144] ;

[0145] wherein, represents the load current, represents the corrected current, represents the theoretical no-load current corresponding to the i-th no-load mode (i.e., the current no-load mode).

[0146] Optionally, the electronic device can further determine the battery state of the target battery, specifically comprising: determining the load power based on the product of the load current, the battery voltage and the conversion efficiency; and / or integrating the corrected current in ampere-hours, and determining the SOC based on the integration result. In other embodiments, the electronic device can also determine other types of battery states, and the present embodiment does not limit the content included in the battery state.

[0147] Optionally, the processing component can also output the battery state, which at least includes the battery state determined based on the load current or the corrected current. In other embodiments, the processing component can also obtain other types of battery states, such as the duration of the current no-load mode, and the present embodiment does not limit the type of battery state output by the processing component.

[0148] In this embodiment, the load current is determined based on the difference between the corrected current and the theoretical no-load current in the case that the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode, so as to determine the battery state of the target battery based on the load current; the problem that the system power consumption current and the load current cannot be separated by the traditional current detection method, resulting in a large error between the load power determined by using the sum of the system power consumption current and the load current and the actual load power, can be solved; since the current correction coefficient can correct the sampling current to a more accurate current value, the load current can be extracted by using the corrected current minus the theoretical no-load current, so the accuracy of the estimated load power can be ensured.

[0149] In addition, the current detection method provided by the embodiment can realize more accurate load current detection without the need of additional high-precision current collection hardware, so as to improve the current detection efficiency and reduce the cost of the energy storage system.

[0150] In order to more clearly understand the current detection method of the energy storage system provided by the present application, the following will illustrate an example of the method, and the present embodiment takes at least two no-load modes including a first no-load mode, a second no-load mode, a third no-load mode and a fourth no-load mode as an example for illustration, and the method is described with reference to Figure 3 The method comprises the following steps.

[0151] In step 31, the switching states of the AC circuit and the DC circuit in the energy storage system are obtained.

[0152] In step 32, the current no-load mode is determined based on the switching states, and the current no-load mode corresponding current correction coefficient is obtained; if the current no-load mode is the first no-load mode, the current no-load mode is marked as the first mark, and the first mark indicates that the current no-load mode is the first no-load mode; if the current no-load mode is the second no-load mode, the current no-load mode is marked as the second mark, and the second mark indicates that the current no-load mode is the second no-load mode; if the current no-load mode is the third no-load mode, the current no-load mode is marked as the third mark, and the third mark indicates that the current no-load mode is the third no-load mode; if the current no-load mode is the fourth no-load mode, the current no-load mode is marked as the fourth mark, and the fourth mark indicates that the current no-load mode is the fourth no-load mode.

[0153] In step 33, the sampling current is obtained.

[0154] In step 34, the data range to which the sampling current belongs is determined; if the sampling current belongs to the first data range, step 35 is performed; if the sampling current belongs to the second data range, step 36 is performed; if the sampling current belongs to the third data range, step 37 is performed.

[0155] In step 35, the sampling current is corrected by using the current correction coefficient corresponding to the current no-load mode, so as to obtain the corrected current, and step 38 is performed.

[0156] Step 36, determining the corrected current as the theoretical no-load current, and performing step 38;

[0157] Step 37, determining the corrected current as the sampling current;

[0158] Step 38, determining whether the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode; if yes, performing step 39; if no, performing step 391;

[0159] Step 39, subtracting the difference between the corrected current and the theoretical no-load current to obtain the load current; determining the battery state based on the load current, and performing step 392;

[0160] Step 391, determining the battery state based on the corrected current;

[0161] Step 392, outputting the battery state.

[0162] In the embodiment, by using the corrected current minus the theoretical no-load current, the load current can be extracted, and the accuracy of the battery state estimation is ensured.

[0163] In order to more clearly understand the precision improvement effect brought by the current detection method provided in the present application, the method is exemplified as follows. Assuming that the first array composed of the no-load power and the theoretical no-load current (as shown in Table 1) of each no-load mode in the first no-load mode, the second no-load mode, the third no-load mode and the fourth no-load mode is respectively (5, 0.104), (8, 0.167), (13, 0.271) and (1, 0.021), and the current curve of the theoretical no-load current can be determined based on the first array. The second array composed of the no-load power and the actual no-load current (as shown in Table 1) of each no-load mode is respectively (5, 0.08), (8, 0.129), (13, 0.209) and (1, 0.021), and the current curve of the actual no-load current can be determined based on the second array. The third array composed of the actual no-load current corresponding to the corrected current corresponding to the no-load power of each no-load mode is respectively (5, 0.104), (8, 0.167), (13, 0.271) and (1, 0.021), and the current curve of the corrected current can be determined based on the third array.

[0164] According to the above array, the current change M corresponding to the unit power change can be represented as:

[0165] ;

[0166] wherein, and represent the no-load power in any two groups of the first array or the second array, and represents the theoretical no-load current or the actual no-load current or the corrected current corresponding to the no-load power in any two groups of arrays.

[0167] Correspondingly, the relative deviation between the actual current curve and the corrected current curve and the theoretical current curve may be expressed as:

[0168] ;

[0169] wherein, in and , when the actual no-load current is represents the change of the actual no-load current corresponding to the unit power change (hereinafter referred to as the slope of the actual no-load current); in and , when the corrected current is represents the change of the corrected current corresponding to the unit power change (hereinafter referred to as the slope of the corrected current). represents the change of the theoretical no-load current corresponding to the unit power change (hereinafter referred to as the slope of the theoretical no-load current).

[0170] According to the values of the above arrays, it can be known that:

[0171] Theoretical no-load current slope: ;

[0172] Actual no-load current slope: ;

[0173] Corrected current slope: .

[0174] According to the above slope values, the corresponding relationship between the current type and the relative deviation shown in Table Three is obtained.

[0175] Table Three:

[0176]

[0177] Wherein, the smaller the relative deviation, the closer the current to the theoretical value, and the higher the accuracy. According to Table Three, after the sampling current in the first data range is corrected by the current detection method of the present application, the relative deviation is reduced from 23% to 0%, and the current detection accuracy is obviously improved.

[0178] Based on the above data, an exemplary technical parameter of the current detection of the energy storage system is shown in Table Four.

[0179] Table Four:

[0180]

[0181] Figure 4 is a block diagram of a current detection device of an energy storage system provided by an embodiment of the present application. The embodiment takes the device applied to the energy storage system as shown in the figure. Figure 1 The processing component in the current detection device of the energy storage system is taken as an example for description. The device at least includes the following modules: a data acquisition module 410, a coefficient acquisition module 420 and a current correction module 430.

[0182] The data acquisition module 410 is configured to acquire a current no-load mode and a sampling current of a target battery to be detected in the energy storage system; the target battery includes at least two no-load modes.

[0183] The coefficient acquisition module 420 is configured to acquire a current correction coefficient corresponding to the current no-load mode.

[0184] The current correction module 430 is configured to correct the sampling current based on the current correction coefficient to obtain a corrected current in a case where the sampling current belongs to a first data range; wherein the current correction coefficient is used to correct a deviation between a theoretical no-load current and an actual no-load current corresponding to the current no-load mode.

[0185] Optionally, the device further includes a current detection module configured to determine a load current based on a difference between the corrected current and the theoretical no-load current in a case where the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode.

[0186] For related details, refer to the above method embodiments.

[0187] It should be noted that the current detection device of the energy storage system provided in the above embodiments is only taken as an example for description of the division of the functional modules, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the current detection device of the energy storage system is divided into different functional modules to complete all or part of the functions described above. In addition, the current detection device of the energy storage system and the current detection method of the energy storage system provided in the above embodiments belong to the same concept, and the specific implementation process is described in the method embodiments, which will not be repeated here.

[0188] Figure 5 is a block diagram of a current detection device of an energy storage system provided by an embodiment of the present application. The device can be a device including Figure 1The device shown in the current detection device of the energy storage system can be a device such as a smartphone, a tablet computer, a notebook computer, a desktop computer, or a server. The current detection device of the energy storage system can also be referred to as a user equipment, a portable terminal, a laptop terminal, a desktop terminal, a control terminal, and the like, and the embodiments are not limited thereto. The device at least includes a processor 501 and a memory 502.

[0189] The processor 501 can include one or more processing cores, such as a 4-core processor, an 8-core processor, and the like. The processor 501 can be implemented in at least one of a hardware form of a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), and a PLA (Programmable Logic Array). The processor 501 can also include a main processor and a coprocessor. The main processor is a processor for processing data in an awake state, also referred to as a CPU (Central Processing Unit). The coprocessor is a low-power processor for processing data in a standby state. In some embodiments, the processor 501 can be integrated with a GPU (Graphics Processing Unit) that is responsible for rendering and drawing the content required to be displayed on the display screen. In some embodiments, the processor 501 can further include an AI (Artificial Intelligence) processor for processing machine learning-related computing operations.

[0190] The memory 502 can include one or more computer-readable storage media, which can be non-transitory. The memory 502 can also include a high-speed random access memory and a non-volatile memory such as one or more disk storage devices, flash storage devices. In some embodiments, the non-transitory computer-readable storage medium in the memory 502 is used to store at least one instruction for being executed by the processor 501 to implement the current detection method of the energy storage system provided by the method embodiments in the present application.

[0191] In some embodiments, the current detection device of the energy storage system can further include a peripheral device interface and at least one peripheral device. The processor 501, the memory 502, and the peripheral device interface can be connected through a bus or a signal line. Each peripheral device can be connected to the peripheral device interface through a bus, a signal line, or a circuit board. Illustratively, the peripheral device includes, but is not limited to, a radio frequency circuit, a touch display screen, an audio circuit, and a power supply, and the like.

[0192] Of course, the current detection device of the energy storage system can also include fewer or more components, and the present embodiment is not limited thereto.

[0193] Optionally, the present application also provides a computer readable storage medium, the computer readable storage medium stores a program, the program is loaded and executed by a processor to realize the current detection method of the energy storage system of the above-mentioned method embodiment.

[0194] Optionally, the present application also provides a computer product, which includes a computer readable storage medium, the computer readable storage medium stores a program, the program is loaded and executed by a processor to realize the current detection method of the energy storage system of the above-mentioned method embodiment.

[0195] The technical features of the above-mentioned embodiments can be combined arbitrarily, in order to make the description simple, all possible combinations of the technical features in the above-mentioned embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0196] The above-mentioned embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method of current detection for an energy storage system, the method comprising: The method comprises: obtaining a current no-load mode and a sampling current of a target battery to be detected in the energy storage system; the target battery comprises at least two no-load modes; obtaining a current correction coefficient corresponding to the current no-load mode; wherein the current correction coefficient is used to correct the deviation between the theoretical no-load current corresponding to the current no-load mode and the actual no-load current; in the case that the sampling current belongs to a first data range, correcting the sampling current based on the current correction coefficient to obtain a corrected current.

2. The method of claim 1, wherein, After the current correction coefficient corresponding to the current no-load mode is obtained, the method further comprises: in the case that the corrected current is greater than the theoretical no-load current corresponding to the current no-load mode, determining a load current based on the difference between the corrected current and the theoretical no-load current.

3. The method of claim 1, wherein, The method further comprises: determining the ratio of the theoretical no-load current corresponding to the current no-load mode to the actual no-load current value in the no-load state to obtain the current correction coefficient.

4. The method of claim 1, wherein, The method further comprises: in at least one other no-load mode except the current no-load mode in the at least two no-load modes, obtaining the no-load power of m other no-load modes in the at least one other no-load mode in the no-load state; m is a positive integer; determining the coefficient adjustment weight of each other no-load mode relative to the current no-load mode based on the similarity between the no-load power corresponding to each other no-load mode and the no-load power corresponding to the current no-load mode; determining the current ratio of the theoretical no-load current corresponding to each other no-load mode to the actual no-load current value in the no-load state; determining the weighted sum value of the coefficient adjustment weight and the current ratio corresponding to m other no-load modes to obtain the current correction coefficient.

5. The method of claim 4, wherein, The method further comprises: for each other no-load mode in the m other no-load modes, determining the absolute value of the difference between the no-load power corresponding to the other no-load mode and the no-load power corresponding to the current no-load mode; determining the coefficient adjustment weight based on the reciprocal of the sum of the absolute value and a preset value.

6. The method of claim 5, wherein, The method further comprises: based on the sum of the reciprocals corresponding to the m other no-load modes, normalizing the reciprocal corresponding to each other no-load mode to obtain the coefficient adjustment weight corresponding to each other no-load mode.

7. The method according to any one of claims 1 to 6, characterized in that, The method further comprises: in the case that the sampling current belongs to a second data range, determining that the corrected current is the theoretical no-load current; in the case that the sampling current belongs to a third data range, determining that the corrected current is the sampling current. Each value in the second data range is less than the minimum value of the first data range, and each value in the third data range is greater than the maximum value of the first data range.

8. The method according to any one of claims 1 to 6, characterized in that, The at least two kinds of no-load modes include at least one of the following: The first no-load mode refers to a state that a DC circuit in the energy storage system is turned on, an AC circuit is turned off, and the energy storage system is not connected to a load. The second no-load mode refers to a state that the AC circuit in the energy storage system is turned on, the DC circuit is turned off, and the energy storage system is not connected to the load. The third no-load mode refers to a state that the AC circuit and the DC circuit in the energy storage system are turned on, and the energy storage system is not connected to the load. The fourth no-load mode refers to a state that the AC circuit and the DC circuit in the energy storage system are turned off, and the energy storage system is not connected to the load.

9. A current detection device for an energy storage system, characterized by The device includes a processor and a memory; the memory stores a program, and the program is loaded and executed by the processor to implement the current detection method of the energy storage system according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The storage medium stores a program, and the program is executed by the processor to implement the current detection method of the energy storage system according to any one of claims 1 to 8.

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