Uninterruptible power supply system and method for monitoring internal resistance of battery of uninterruptible power supply system

Abstract

The invention discloses an uninterruptible power supply system and a method for monitoring the internal resistance of a battery of the uninterruptible power supply system. The method comprises the following steps: when the voltage of a target monitoring device is reduced to a preset voltage value, acquiring a first voltage of the target monitoring device; the target monitoring device is a battery or a single battery; controlling the target monitoring device to charge, and acquiring a first current and a second voltage of the target monitoring device at a first preset moment in the charging process; calculating the charging internal resistance of the target monitoring device according to the first voltage, the first current and the second voltage; and determining the health state of the target monitoring device according to the charging internal resistance of the target monitoring device. Most working conditions of the uninterruptible power supply system are charging working conditions, and the discharging working conditions do not exist for a long time, so that the internal resistance of the battery is calculated by starting the charging process after the battery in the system is powered down, and real-time online monitoring of the battery is realized so as to determine the health state of the battery in the uninterruptible power supply system in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of online monitoring of uninterruptible power supply, and particularly relates to an uninterruptible power supply system and a method for monitoring battery internal resistance of the uninterruptible power supply system. BACKGROUND

[0002] The DC internal resistance (DCIR) of a lithium battery is a key performance parameter, which comprehensively reflects the total resistance under real working conditions such as internal ohmic resistance, electrochemical polarization impedance and concentration polarization impedance, and is a key evaluation index for evaluating the service life and aging state of the battery.

[0003] In the related technologies of energy storage and backup power supply, there is an urgent need for a solution that can accurately realize online monitoring of the battery internal resistance of an uninterruptible power supply system. SUMMARY

[0004] The present application provides an uninterruptible power supply system and a method for monitoring battery internal resistance of the uninterruptible power supply system, so as to realize online monitoring of the battery internal resistance of the uninterruptible power supply system.

[0005] According to an aspect of the present application, a method for monitoring battery internal resistance of an uninterruptible power supply system is provided, the uninterruptible power supply system comprising a battery, the battery comprising a plurality of battery monomers in series and / or parallel; the online monitoring method of the battery internal resistance of the uninterruptible power supply comprises:

[0006] When the voltage of the target monitoring device decreases to a preset voltage value, the first voltage of the target monitoring device is obtained; the target monitoring device is the battery or the battery monomer;

[0007] The target monitoring device is charged, and the first current and the second voltage of the target monitoring device are obtained at a first preset time during the charging process;

[0008] The charging internal resistance of the target monitoring device is calculated according to the first voltage, the first current and the second voltage;

[0009] The health state of the target monitoring device is determined according to the charging internal resistance of the target monitoring device.

[0010] Optionally, the uninterruptible power supply system comprises a battery, a main charging circuit and a pre-charging circuit, the main charging circuit is connected between the battery and an energy end, the pre-charging circuit is connected between the battery and the energy end, and the resistance of the pre-charging circuit is greater than that of the main charging circuit;

[0011] The target monitoring device is charged, and the first current and the second voltage of the target monitoring device are obtained at a first preset time during the charging process;

[0012] The main charging circuit is controlled to be closed to charge the target monitoring device through the main charging circuit.

[0013] Optionally, the first preset time length is less than a first preset threshold.

[0014] Optionally, the controlling the charging of the target monitoring device comprises:

[0015] controlling the charging of the target monitoring device to stop charging when the charging time length is set;

[0016] The method further comprises, after the calculating the charging internal resistance of the target monitoring device according to the first voltage, the first current and the second voltage:

[0017] when it is determined that the target monitoring device is not charged to the full charge state, returning to the step of acquiring the first voltage of the target monitoring device to charge the target monitoring device to the full charge state through intermittent charging;

[0018] The determining the health state of the target monitoring device according to the charging internal resistance of the target monitoring device comprises:

[0019] The determining the health state of the target monitoring device according to the charging internal resistance of the target monitoring device according to the charging internal resistance of the target monitoring device and the discharging internal resistance of the target monitoring device.

[0020] Optionally, after the controlling the charging of the target monitoring device to stop charging when the charging time length is set, the method further comprises, after a preset resting time length, returning to the step of acquiring the first voltage of the target monitoring device.

[0021] Optionally, the method for monitoring the internal resistance of the battery of the uninterruptible power supply system further comprises:

[0022] when the target monitoring device is in a discharging working condition, acquiring a third voltage of the target monitoring device before discharging;

[0023] controlling the discharging of the target monitoring device;

[0024] at a second preset time during the discharging, acquiring a second current and a fourth voltage of the target monitoring device;

[0025] calculating a discharging internal resistance of the target monitoring device according to the third voltage, the second current and the fourth voltage;

[0026] The determining the health state of the battery of the uninterruptible power supply system according to the charging internal resistance of the target monitoring device comprises:

[0027] The determining the health state of the target monitoring device according to the charging internal resistance of the target monitoring device and the discharging internal resistance of the target monitoring device.

[0028] Optionally, the second preset time is a second preset time length away from a starting time of the discharge of the target monitoring device, and the second preset time length is less than a second set threshold.

[0029] Optionally, when it is determined that the target monitoring device meets a condition that a time length in a resting state before the discharge is greater than a third preset time length, the second current and the fourth voltage of the target monitoring device are acquired at the second preset time.

[0030] Optionally, after the calculation of the charging internal resistance of the target monitoring device according to the first voltage, the first current and the second voltage, the method further comprises:

[0031] training a sample set of the target monitoring device acquired under different working conditions to obtain a health state prediction model to determine the health state of the target monitoring device according to the health state prediction model; input features of the sample set include temperature, first voltage, first current and second voltage, and labels of the sample set include excellent, good and poor; the labels are calibrated based on the charging internal resistance calculated under the corresponding input features.

[0032] According to another aspect of the present application, an uninterrupted power supply system is provided, which comprises a battery including a plurality of battery monomers connected in series and / or in parallel; the uninterrupted power supply system adopts the method for monitoring the internal resistance of the battery of the uninterrupted power supply system of the above aspect to monitor the internal resistance.

[0033] The technical solution of the embodiment of the present application respectively acquires the voltage and the current before and during the discharge of the target monitoring device, calculates the charging internal resistance of the target monitoring device according to the voltage change and the current change, and then determines the health state of the battery in the uninterrupted power supply system according to the size of the charging internal resistance. Since most working conditions of the uninterrupted power supply system are charging conditions, and there is no discharge condition for a long time, the internal resistance of the battery is calculated by means of the starting charging process after the battery in the system is powered off, the real-time online monitoring of the battery is realized, and the health state of the battery in the uninterrupted power supply system is determined in real time.

[0034] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A flowchart illustrating a method for monitoring the internal resistance of a battery in an uninterruptible power supply system, provided as an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the structure of an uninterruptible power supply system provided in an embodiment of the present invention;

[0038] Figure 3 A flowchart illustrating another method for monitoring the internal resistance of a battery in an uninterruptible power supply system, provided as an embodiment of the present invention. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0041] Figure 1 A flowchart illustrating a method for monitoring the internal resistance of a battery in an uninterruptible power supply system, as provided in an embodiment of the present invention, is shown below. Figure 1 The method includes:

[0042] S110: When the voltage of the target monitoring device drops to a preset voltage value, the first voltage of the target monitoring device is acquired; the target monitoring device is a battery or a battery cell of an uninterruptible power supply system.

[0043] An uninterruptible power supply (UPS) system includes a battery, which comprises multiple battery cells connected in series and / or parallel. The health status of the battery can be determined by monitoring the internal resistance of the battery cells, or by monitoring the internal resistance of a single battery cell. The overall health status of the battery is then determined based on the health status of the individual battery cells. In this embodiment, "battery" can also refer to a battery pack, battery stack, or battery cluster.

[0044] Uninterruptible power supply (UPS) systems can be applied to data center backup power applications. The main function of an UPS is to provide backup power to server rooms and start generators via float charging. The system operates primarily in float charging or supplemental charging modes. As standby time increases, the UPS consumes more power, causing the voltage of the target monitoring device to drop. Therefore, the voltage of the target monitoring device in the UPS system must be maintained above a certain level, such as 80%. When the voltage of the target monitoring device drops to a preset voltage value, the battery needs to be charged. The preset voltage value can be set according to requirements; this embodiment does not impose a specific limitation. Before charging the target monitoring device, its voltage is measured when it drops to the preset voltage value and recorded as the first voltage. The battery includes positive and negative terminals, with multiple battery cells connected between them. When the target monitoring device is a battery, the voltage difference between the positive and negative terminals of the target monitoring device before charging is used as the first voltage. When the target monitoring device is a battery cell, the voltage difference between the two ends of the battery cell before charging is used as the first voltage. The voltage of the target monitoring device can be obtained through devices such as resistive voltage dividers and Hall effect voltage sensors. Any device that can detect voltage is acceptable, and there are no specific limitations.

[0045] S120: Control the target monitoring device to charge, and acquire the first current and second voltage of the target monitoring device at the first preset moment during the charging process.

[0046] By closing the charging circuit, the electrical energy provided by the charger is supplied to the target monitoring device via the energy storage converter, thereby charging the target monitoring device. Furthermore, the charging circuit may include a charging switch, which is closed to activate the charging circuit. At a certain moment during the charging process, the voltage of the target monitoring device is acquired by a voltage sensor and recorded as the second voltage, and the current of the target monitoring device is acquired by a current sensor, such as a Hall effect current sensor, and recorded as the first current. When the target monitoring device is a battery, the first current can be the current flowing into the positive terminal or out of the negative terminal of the battery at a first preset moment; when the target monitoring device is a single battery cell, the first current is the current flowing through that single battery cell at the first preset moment.

[0047] S130: Calculate the charging internal resistance of the target monitoring device based on the first voltage, the first current, and the second voltage.

[0048] The charging internal resistance of the target monitoring device is equal to the ratio of the voltage difference before and after charging to the current difference before and after charging. Since the current of the target monitoring device is 0 before charging, the charging internal resistance of the target monitoring device is R1 = (V2 - V1) / I1, where V1 is the first voltage, V2 is the second voltage, and I1 is the first current.

[0049] S140: Determine the health status of the target monitoring device based on its internal charging resistance.

[0050] The internal resistance of the target monitoring device, measured during charging, characterizes its internal resistance. As the battery ages, the internal resistance gradually increases; therefore, the health status of the target monitoring device can be determined based on the internal resistance. The internal resistance is divided into different ranges, each corresponding to a different health status. For example, when the internal resistance is between the first and second internal resistance thresholds, the target monitoring device's health status is excellent; between the second and third internal resistance thresholds, it is good; and between the third and fourth internal resistance thresholds, it is poor. The first, second, third, and fourth internal resistance thresholds increase sequentially. The four internal resistance thresholds differ when the target monitoring device is a single battery cell compared to when it is a battery. When the target monitoring device is a single battery cell, the health status of the battery cell also characterizes the battery's health status. A higher internal resistance in a single battery cell indicates a poorer health status, reflecting severe battery aging and a generally poor health condition. Furthermore, when the target monitoring device is a single battery cell, if the health status of more than a preset percentage of the battery cells does not meet the requirements, then the health status of the uninterruptible power supply system's battery is determined to be unacceptable. For example, if the health status of more than 40% of the battery cells is poor, then the health status of the uninterruptible power supply system's battery is determined to be unacceptable.

[0051] The technical solution of this invention acquires the voltage and current of the target monitoring device before and during discharge. Based on the voltage and current changes, the charging internal resistance of the target monitoring device is calculated, and then the health status of the battery in the uninterruptible power supply (UPS) system is determined based on the magnitude of the charging internal resistance. Since the UPS system operates primarily in charging mode and discharge mode is absent for extended periods, the internal resistance of the battery is calculated by utilizing the charging process initiated after the battery loses power, enabling real-time online monitoring of the battery and determining its health status in the UPS system. Furthermore, this embodiment eliminates the need to create additional charging conditions; it directly utilizes the current and voltage changes collected during the battery recharging process in the UPS system to calculate the internal resistance, resulting in higher efficiency.

[0052] Figure 2 This is a schematic diagram of an uninterruptible power supply system provided in an embodiment of the present invention, with reference to... Figure 2 The system includes a battery, a main charging circuit 10, and a pre-charging circuit 11. The main charging circuit 10 is connected between the battery and the power terminal, and the pre-charging circuit 11 is connected between the battery and the power terminal. The resistance of the pre-charging circuit 11 is greater than the resistance of the main charging circuit 10.

[0053] The power terminal includes a positive terminal PCS+ and a negative terminal PCS-. The positive terminal PCS+ is connected to the positive terminal BAT+ of the battery through the main charging circuit 10 or the pre-charge circuit 11, and the negative terminal PCS- is connected to the negative terminal BAT- of the battery through the main charging circuit 10 or the pre-charge circuit 11. The main charging circuit 10 and the pre-charge circuit 11 are connected in parallel between the battery and the power terminal. Figure 2 As shown, the main charging circuit 10 includes a first switch KM1 and a second switch KM2 connected in series. The pre-charge circuit 11 includes a third switch KM3 and a pre-charge resistor R0. The first switch KM1, the second switch KM2, and the third switch KM3 can all be relays. This embodiment only exemplifies the inclusion of three switches; it may also include protective devices such as fuses connected between the battery and the power source, but this is not specifically limited. The uninterruptible power supply system is in float charging or supplementary charging mode most of the time. Once the battery level drops to a preset level, such as 80%, the pre-charge circuit 11 will be closed to charge the battery. The pre-charge resistor in the pre-charge circuit 11 ensures a small charging current, charging the battery to full capacity with a small current. Only when the battery is completely depleted will the main charging circuit 10 be closed to charge the battery to full capacity as quickly as possible with a large current.

[0054] Referring to the Hybrid Pulse Power Characterization (HPPC) method, a series of predetermined large pulse currents are used to stimulate the battery or individual battery cells. The internal resistance calculated under these conditions is the internal resistance of the battery or individual battery cells. In related technologies, uninterruptible power supply systems are mostly in float charging or supplementary charging mode to bring the battery close to full charge. Supplementary charging through the pre-charge circuit 11 results in a very small current, less than 1A, which cannot obtain a large pulse current, leading to a large error in the calculated internal resistance. Therefore, in this embodiment, the battery is also charged through the main charging circuit 10 during supplementary charging to obtain a larger pulse current. Specifically, controlling the charging of the target monitoring device includes: controlling the main charging circuit 10 to close, and further controlling the first switch KM1 and the second switch KM2 to close so that the target monitoring device can be charged through the main charging circuit 10, so that a large pulse current exists during the charging process, and the maximum pulse current value is greater than the current threshold.

[0055] Optionally, the first preset time is a first preset duration from the start of charging of the target monitoring device, and this first preset duration is less than a first set threshold. Because the current in the target monitoring device increases and then decreases after charging begins, long after charging starts, the current in the target monitoring device has dropped back to a smaller current value and is no longer in the large pulse current stage. Therefore, the resistance value calculated based on this small current cannot accurately represent the internal resistance of the target monitoring device. Thus, by collecting the current of the target monitoring device shortly after the start of charging, such as at the second second after charging begins, the current collected is ensured to be in the pulse stage. The resistance value calculated based on this collected current can better represent the internal resistance of the target monitoring device. Optionally, the first set threshold can be any value between 2 and 5 seconds, or it can be set according to the specific conditions of the battery.

[0056] The above embodiments determine the health status of the target monitoring device based on a single measured charging internal resistance, which may result in false alarms. Therefore, the health status of the target monitoring device can be characterized by the average value of multiple measured charging internal resistances, thereby improving the accuracy of internal resistance monitoring. Figure 3 A flowchart illustrating another method for monitoring the internal resistance of a battery in an uninterruptible power supply system provided by an embodiment of the present invention is shown below. Figure 3 The method includes:

[0057] S111: Obtain the first voltage of the target monitoring device.

[0058] When the voltage of the target monitoring device drops to a preset voltage value, the first voltage of the target monitoring device is acquired.

[0059] S121: Control the target monitoring device to stop charging when the charging time is set, and acquire the first current and second voltage of the target monitoring device at the first preset moment during the charging process.

[0060] Optionally, the first preset time is a first preset duration from the start time of charging of the target monitoring device.

[0061] S131: Calculate the charging internal resistance of the target monitoring device based on the first voltage, the first current, and the second voltage.

[0062] S141: Determine whether the target monitoring device is fully charged. If yes, execute S151; otherwise, return to execute S111.

[0063] If it is determined that the target monitoring device is not fully charged, the process returns to the step of obtaining the first voltage of the target monitoring device to charge it to full charge through intermittent charging. An internal resistance is calculated during each charging process. When it is determined that the target monitoring device is fully charged, step S151 is executed.

[0064] Optionally, after stopping charging when the target monitoring device is charged for a set charging time, the process can be paused for a preset time before returning to the step of obtaining the first voltage of the target monitoring device.

[0065] Because the charge within a single battery cell is unstable immediately after charging stops, charge migration can affect the internal resistance. After charging is complete and the device is left to stand for a period of time, such as 10 minutes, the charge stabilizes and the resulting internal resistance changes recover. Therefore, after charging stops, the target monitoring device is left to stand for a period of time before measuring its first voltage. This avoids including errors caused by recoverable charge migration in the final calculated internal resistance. When the target monitoring device is in a static state, it neither charges nor discharges. Optionally, the preset static time can be any value between 10 and 30 minutes, or it can be set according to actual conditions.

[0066] S151: Determine the health status of the target monitoring device based on the average value of the charging internal resistance of the target monitoring device calculated multiple times during the process of charging the target monitoring device to full charge.

[0067] When the voltage of the target monitoring device drops to a preset voltage value, the target monitoring device needs to be charged to a fully charged state. In this embodiment, the charging process is controlled as an intermittent charging process, that is, the target monitoring device is charged for a set time and then stopped, and then charged for a set time and stopped again, and the operation is repeated until the target monitoring device is fully charged. During each charging process, the voltage before charging, the voltage during charging, and the current are acquired to calculate the internal resistance of one charging cycle. The average value of the internal resistance calculated in multiple charging cycles is calculated, and the health status of the target monitoring device is determined based on the average value of the internal resistance. This avoids misjudgment caused by determining the health status of the target monitoring device based on the internal resistance calculated in a single cycle, and improves the accuracy of determining the health status of the target monitoring device. In other embodiments, the internal resistance can also be calculated once during the process of charging the target monitoring device from the preset voltage value to a fully charged state, and then the internal resistance can be calculated again during the next process of charging the target monitoring device from the preset voltage value to a fully charged state. The average value of the internal resistance obtained from multiple calculations can be calculated to eliminate false alarms. Compared to the average charging resistance calculated by continuously charging the target monitoring device, this embodiment breaks down the process of charging the target monitoring device to full charge into multiple intermittent charging processes to shorten the time for calculating the average charging resistance, thereby enabling timely monitoring of the health status of the target monitoring device.

[0068] In an uninterruptible power supply (UPS) system, the internal resistance of a battery or its individual cells can be calculated not only through voltage and current changes during charging but also through voltage and current changes during discharging. Therefore, if a target monitoring device is in a discharging state, its discharging internal resistance can also be calculated through voltage and current changes during discharging. Specifically, when the target monitoring device is in a discharging state, the third voltage of the target monitoring device before discharging is acquired; the target monitoring device is controlled to discharge; at a second preset time during the discharging process, the second current and fourth voltage of the target monitoring device are acquired; the second preset time can be any time during the discharging process; the discharging internal resistance of the target monitoring device is calculated based on the third voltage, second current, and fourth voltage. The health status of the target monitoring device is determined based on its charging and discharging internal resistances.

[0069] Before discharging, the voltage of the target monitoring device is obtained by a voltage sensor and recorded as the third voltage. Figure 2 The main charging circuit 10 can also serve as a discharging circuit. Closing the first switch KM1 and the second switch KM2 controls the flow of electrical energy from the target monitoring device to the power terminal, thus discharging the target monitoring device. At a second preset moment during the discharge process, the current of the target monitoring device is collected by a current sensor and recorded as the second current, and the voltage of the target monitoring device is collected by a voltage sensor and recorded as the fourth voltage. The discharge internal resistance of the target monitoring device is equal to the ratio of the voltage difference before and after discharge to the current difference before and after discharge. Since the current of the target monitoring device is 0 before discharge, the discharge internal resistance R2 = (V3 - V4) / I1, where V3 is the third voltage, V4 is the fourth voltage, and I2 is the second current. For certain types of batteries, when the charging internal resistance calculated during charging and the discharging internal resistance calculated during discharging can both be directly represented as the internal resistance of the target monitoring device, and the difference between the two is within a certain range, the average value of the charging internal resistance and the discharging internal resistance of the target monitoring device can be calculated. This average value is then used as the internal resistance of the target monitoring device to further determine its health status. For other types of batteries, where the charging internal resistance and discharging internal resistance differ significantly, the health status of the target monitoring device can be determined based on either the charging or discharging internal resistance. Alternatively, if the health status determined by the charging and discharging internal resistances are the same, then the corresponding health status is the health status of the target monitoring device. Since discharging conditions are extremely rare in uninterruptible power supply systems, the health status can be determined solely based on the discharging internal resistance obtained from a single operation.

[0070] Optionally, the second preset time is a second preset duration from the start of discharge of the target monitoring device, and the second preset duration is less than a second set threshold. The second set threshold can be 5 seconds. Similar to obtaining a large pulse current during charging, it is also necessary to acquire the current within a short period of time before discharge so that the acquired current is in the pulse phase. Therefore, the current of the target monitoring device needs to be acquired within a short period of time after the discharge starts. Optionally, the second set threshold can be any value between 2 seconds and 5 seconds.

[0071] Optionally, when it is determined that the target monitoring device satisfies the condition that the duration of its resting state before discharge is greater than a third preset duration, the second current and fourth voltage of the target monitoring device are acquired at a second preset time. Similar to the charging process, if the voltage before discharge is acquired again immediately after charging or discharging, the internal resistance of the target monitoring device will fluctuate due to charge migration caused by the unstable charge within the device during the recent charging or discharging process, resulting in inaccurate calculations. Therefore, when acquiring the voltage of the target monitoring device before discharge, it is necessary to ensure that the target monitoring device remains resting for a sufficient duration to avoid fluctuations in internal resistance caused by charge migration. Optionally, the third preset duration can be any value between 20 and 40 minutes, or it can be set according to the specific characteristics of the target monitoring device.

[0072] Optionally, after calculating the charging internal resistance of the target monitoring device based on the first voltage, the first current, and the second voltage, the method further includes:

[0073] A health status prediction model is trained on a sample set of target monitoring devices acquired under different operating conditions to determine the health status of the target monitoring devices. The input features of the sample set include temperature, first voltage, first current and second voltage, and the labels of the sample set include excellent, good and poor. The labels are calibrated based on the charging internal resistance calculated under the corresponding input features.

[0074] The charging internal resistance of the target monitoring device under different operating conditions can be obtained through the steps in any of the above embodiments. After obtaining the charging internal resistance, the specific health status of the target monitoring device can be determined according to the correspondence between the charging internal resistance and the health status. By collecting input features under different operating conditions using the above method, and then calculating the charging internal resistance based on the first voltage, first current, and second voltage in the input features, the specific health status of the target monitoring device can be determined based on the charging internal resistance and manually calibrated. This yields multiple sample sets, each consisting of input features and labels. A health status prediction model is generated by training multiple sample sets using methods such as decision trees or random forests. After the model training is complete, it can be applied online. By inputting the online collected first voltage, first current, and second voltage into the health status prediction model, the corresponding health status will be output, thus improving the monitoring accuracy.

[0075] This invention also provides an uninterruptible power supply (UPS) system, which includes a battery. The battery includes multiple battery cells connected in series and / or in parallel. The UPS system uses the battery internal resistance monitoring method of any of the above embodiments to monitor the internal resistance, and has the same technical effect as the method, which will not be described again here.

[0076] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0077] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method of monitoring the internal resistance of a battery of an uninterruptible power supply system, characterized by, The uninterrupted power supply system comprises a battery, the battery comprising a plurality of battery cells connected in series and / or in parallel; The uninterrupted power supply battery internal resistance online monitoring method comprises: When the voltage of the target monitoring device decreases to a preset voltage value, a first voltage of the target monitoring device is acquired; the target monitoring device is the battery or the battery cell; The target monitoring device is controlled to be charged, and a first current and a second voltage of the target monitoring device are acquired at a first preset time during the charging process; The charging internal resistance of the target monitoring device is calculated according to the first voltage, the first current and the second voltage; The health state of the target monitoring device is determined according to the charging internal resistance of the target monitoring device.

2. The method of claim 1, wherein the battery resistance is monitored by: The uninterrupted power supply system comprises a battery, a main charging circuit and a pre-charging circuit, the main charging circuit being connected between the battery and a power terminal, the pre-charging circuit being connected between the battery and the power terminal, the resistance of the pre-charging circuit being greater than that of the main charging circuit; The target monitoring device is controlled to be charged, and a first current and a second voltage of the target monitoring device are acquired at a first preset time during the charging process; The main charging circuit is controlled to be closed to charge the target monitoring device through the main charging circuit.

3. The method of claim 1, wherein the battery resistance is monitored by: The first preset time is a first preset time length from the starting time of the charging of the target monitoring device, and the first preset time length is less than a first set threshold.

4. The method of claim 1, wherein the battery resistance is monitored by: The target monitoring device is controlled to be charged, and a first current and a second voltage of the target monitoring device are acquired at a first preset time during the charging process; The target monitoring device is controlled to be charged, and a first current and a second voltage of the target monitoring device are acquired at a first preset time during the charging process; After the charging internal resistance of the target monitoring device is calculated according to the first voltage, the first current and the second voltage, the method further comprises: When it is determined that the target monitoring device is not charged to a full charge state, the step of acquiring the first voltage of the target monitoring device is executed again to charge the target monitoring device to the full charge state through intermittent charging; The health state of the target monitoring device is determined according to the charging internal resistance of the target monitoring device. The health state of the target monitoring device is determined according to the average value of the charging internal resistance of the target monitoring device calculated multiple times during the process of charging the target monitoring device to the full charge state.

5. The method for monitoring the internal resistance of a battery in an uninterruptible power supply system according to claim 4, characterized in that, After the target monitoring device is controlled to be charged for a set charging time length, the step of acquiring the first voltage of the target monitoring device is executed again after a preset resting time length.

6. The method of claim 1, wherein the battery resistance is monitored by: Further comprising: When the target monitoring device exists a discharging working condition, a third voltage of the target monitoring device before discharging is acquired; The target monitoring device is controlled to be discharged; At a second preset time during the discharging process, a second current and a fourth voltage of the target monitoring device are acquired; The discharging internal resistance of the target monitoring device is calculated according to the third voltage, the second current and the fourth voltage; The health state of the target monitoring device is determined according to the charging internal resistance and the discharging internal resistance of the target monitoring device. The health state of the target monitoring device is determined according to the charging internal resistance and the discharging internal resistance of the target monitoring device.

7. The method of claim 6, wherein the step of determining the battery resistance comprises the step of: determining the battery resistance by measuring the voltage across the battery and the current through the battery. The second preset time is a second preset time length from the starting time of the discharging of the target monitoring device, and the second preset time length is less than a second set threshold.

8. The method of claim 6, wherein the battery resistance is monitored by: In a case where it is determined that the target monitoring device meets a condition that a length of time in a resting state before discharging is greater than a third preset length of time, a second current and a fourth voltage of the target monitoring device are acquired at the second preset time.

9. The method of claim 1, wherein, The method further comprises, after calculating the charging internal resistance of the target monitoring device according to the first voltage, the first current and the second voltage: The sample set of the target monitoring device acquired under different working conditions is trained to obtain a health state prediction model, so as to determine the health state of the target monitoring device according to the health state prediction model; input features of the sample set include temperature, first voltage, first current and second voltage, and labels of the sample set include excellent, good and poor; the labels are calibrated based on the charging internal resistance calculated under the corresponding input features.

10. An uninterruptible power supply system characterized by comprising: The uninterruptible power supply system comprises a battery, and the battery comprises a plurality of battery monomers connected in series and / or in parallel; the uninterruptible power supply system adopts the method for monitoring the internal resistance of the battery of the uninterruptible power supply system according to any one of claims 1-9 to monitor the internal resistance.

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