Overcharge and discharge protection device for energy storage battery

Abstract

The invention provides an over-charge and over-discharge protection device for an energy storage battery. The over-charge and over-discharge protection device comprises a signal collector; the differentiator is electrically connected with the signal collector and is configured to perform differential operation on the received battery voltage and output a slope signal; the delayer comprises a controllable switch, a third capacitor, a third operational amplifier, a second resistor and a third resistor, the first end of the controllable switch is electrically connected with the output end of the differentiator, the second end of the controllable switch is grounded through the third capacitor, and the second end of the controllable switch is further electrically connected with the in-phase input end of the third operational amplifier; the output end of the third operational amplifier serves as the positive electrode output end of the delayer, and the inverted input end of the third operational amplifier is grounded through a second resistor and connected to the output end of the third operational amplifier through a third resistor. The positive pole input end and the negative pole input end of the comparator are electrically connected with the positive pole output end and the negative pole output end of the delayer respectively, and the comparator is configured to output an early warning signal when the battery to be tested is in an overcharge or overdischarge stage.

Description

Technical Field

[0001] The present invention relates to the field of battery safety early warning, and in particular to an overcharge and discharge protection device for an energy storage battery, in particular to an overcharge and discharge protection device for a lithium-ion energy storage battery based on a battery voltage slope. Background Art

[0002] In order to cope with climate change and achieve low-carbon transformation of energy systems, countries around the world are actively promoting the construction of renewable energy, and battery energy storage systems are being promoted. Lithium-ion batteries have received extensive attention in battery energy storage systems due to their high energy density, long cycle life, low self-discharge rate, and low environmental pollution, and are one of the main energy carriers.

[0003] During the long-term charge and discharge cycle of lithium-ion energy storage batteries, the lithium inside the battery will lose its activity, resulting in battery capacity decay. If the battery is overcharged or over-discharged during the cycle, the capacity decay rate will greatly increase, resulting in battery performance loss. Therefore, it is extremely important to limit the battery from entering the overcharge or over-discharge state during operation. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide an overcharge and overdischarge protection device for an energy storage battery.

[0005] In order to achieve the above object, an embodiment of the present invention provides an overcharge and discharge protection device for an energy storage battery, comprising:

[0006] A signal collector is configured to collect the battery voltage of the battery to be tested and filter the battery voltage;

[0007] a differentiator, electrically connected to the signal collector, configured to receive the battery voltage, perform differential operation, and output a slope signal reflecting the rate of change of the battery voltage;

[0008] A delay device, comprising a controllable switch, a third capacitor, a third operational amplifier, a second resistor and a third resistor, wherein the first end of the controllable switch is electrically connected to the output end of the differentiator and serves as a positive input end of the delay device, the second end of the controllable switch is grounded through the third capacitor, the second end of the controllable switch is also electrically connected to the non-inverting input end of the third operational amplifier, the output end of the third operational amplifier serves as a positive output end of the delay device, and the inverting input end of the third operational amplifier is grounded through the second resistor and connected to the output end of the third operational amplifier through the third resistor;

[0009] A comparator, wherein the positive input terminal and the negative input terminal of the comparator are electrically connected to the positive output terminal and the negative output terminal of the delay device respectively, and the comparator is configured to output a warning signal when the battery to be tested is in an overcharge or overdischarge stage.

[0010] In the embodiment of the present application, the overcharge and discharge protection device further includes:

[0011] The PWM signal generator is used to output a PWM signal to the controllable switch.

[0012] In the embodiment of the present application, the capacitance value of the third capacitor is positively correlated with the period of the PWM signal, and the duty cycle of the PWM signal is positively correlated with the capacitance value of the third capacitor.

[0013] In the embodiment of the present application, the resistance value of the second resistor and the resistance value of the third resistor satisfy the following relationship:

[0014]

[0015] Wherein, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor.

[0016] In an embodiment of the present application, the signal collector includes:

[0017] A first operational amplifier and a first capacitor, wherein the non-inverting input terminal of the first operational amplifier is electrically connected to the positive electrode of the battery to be tested, the inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the first operational amplifier, the output terminal of the operational amplifier is grounded through the first capacitor, and the first capacitor is used as a low-pass filter.

[0018] In an embodiment of the present application, the differentiator includes:

[0019] A second capacitor, a second operational amplifier and a first resistor, wherein the first end of the second capacitor is electrically connected to the output end of the first operational amplifier, the second end of the second capacitor is electrically connected to the inverting input end of the second operational amplifier, the non-inverting input end of the second operational amplifier is electrically connected to the output end of the second operational amplifier through the first resistor, and the output end of the second operational amplifier is electrically connected to the first end of the controllable switch as the output end of the differentiator.

[0020] In the embodiment of the present application, the resistance value of the first resistor ranges from 1000 to 10000 ohms, and the capacitance value of the second capacitor ranges from 100 nF to 1000 nF.

[0021] In the embodiment of the present application, the differentiator further includes a low-pass filter, and the output end of the differentiator is grounded through the low-pass filter.

[0022] In the embodiment of the present application, the controllable switch is an NMOS tube, the drain of the NMOS tube is the first end of the controllable switch, and the source is the second end of the controllable switch.

[0023] In an embodiment of the present application, the overcharge and discharge protection device is integrated on a circuit board.

[0024] The above scheme provided by the embodiment of the present application collects the battery voltage in real time through a collector, and the collected battery voltage is connected to a differentiator through a filter to obtain the battery voltage change slope, and the past historical battery voltage slope is retained through a delay device, and then the two slope values ​​are compared. When the real-time voltage slope is greater than the past historical slope, the comparator outputs a high-level signal to form an early warning. The scheme is simple to implement and can accurately realize early warning based on the voltage change characteristics of lithium-ion energy storage batteries in the overcharge and overdischarge stages.

[0025] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0027] Figure 1 is a circuit diagram of an overcharge and discharge protection device for an energy storage battery provided in accordance with an embodiment of the present application;

[0028] Figure 2 It is a logic flow chart of an overcharge and discharge protection device for an energy storage battery performing an overcharge and discharge warning according to an embodiment of the present application.

[0029] Description of Reference Numerals

[0030] A1 1st operational amplifier A2 2nd operational amplifier

[0031] A3 Third operational amplifier A4 Comparator

[0032] C1 First capacitor C2 Second capacitor

[0033] C3 Third capacitor R1 First resistor

[0034] R2 Second resistor R3 Third resistor

[0035] SW1 controllable switch DETAILED DESCRIPTION

[0036] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0037] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations. In the embodiments of this application, some existing solutions in the industry such as certain software, components, and models may be mentioned, which should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use the solution.

[0038] At the end of charge and discharge, the voltage change rate of lithium-ion energy storage batteries will increase significantly. Based on this feature, the embodiment of the present application proposes an inventive concept of extracting the battery voltage slope to detect the charge and discharge status of the lithium battery and send a signal when it is about to enter the overcharge or overdischarge state.

[0039] Figure 1 It is a circuit diagram of an overcharge and discharge protection device for an energy storage battery provided according to an embodiment of the present application. Figure 2 This is a logic flow chart of an overcharge and discharge protection device for an energy storage battery according to an embodiment of the present application for performing an overcharge and discharge warning. Figure 1 and Figure 2 In the embodiment of the present application, the overcharge and discharge protection device may include:

[0040] A signal collector is configured to collect the battery voltage of the battery to be tested and filter the battery voltage;

[0041] a differentiator, electrically connected to the signal collector, configured to receive the battery voltage, perform differential operation, and output a slope signal reflecting the rate of change of the battery voltage;

[0042] A delayer, comprising a controllable switch SW1, a third capacitor C3, a third operational amplifier A3, a second resistor R2 and a third resistor R3, wherein a first end of the controllable switch SW1 is electrically connected to an output end of the differentiator and serves as a positive input end of the delayer, a second end of the controllable switch SW1 is grounded through the third capacitor C3, a second end of the controllable switch SW1 is also electrically connected to a non-inverting input end of the third operational amplifier A3, an output end of the third operational amplifier A3 serves as a positive output end of the delayer, and an inverting input end of the third operational amplifier A3 is grounded through the second resistor R2 and connected to an output end of the third operational amplifier A3 through the third resistor R3;

[0043] Comparator A4, the positive input terminal and the negative input terminal of comparator A4 are electrically connected to the positive output terminal and the negative output terminal of the delay device respectively, and comparator A4 is configured to output a warning signal when the battery to be tested is in an overcharge or overdischarge stage.

[0044] Specifically, in the embodiment of the present application, the overcharge and discharge protection device can be implemented in the form of a circuit board structure, that is, each component or electrical element of the overcharge and discharge protection device can be integrated on the circuit board. The circuit board can be provided with a zero potential terminal.

[0045] The signal collector (referred to as the collector) may include a first operational amplifier A1 and a filter (e.g., a first capacitor C1). The positive input terminal of the collector may be the in-phase input terminal of the first operational amplifier A1, which may be electrically connected to the positive electrode of the battery to be tested when in use. The negative input terminal of the collector may be the zero potential point of the first operational amplifier A1 (not shown in the figure), which may be electrically connected to the negative electrode of the battery to be tested when in use. In the selection of the first operational amplifier A1, its input impedance may be large enough, and the input current may be small, so as not to affect the normal operation of the battery. The output terminal of the first operational amplifier A1 is short-circuited with its inverting input terminal, and constitutes the positive output terminal of the collector. In this case, the ratio of the collected output voltage to the input voltage is 1. The negative output terminal of the collector is electrically connected to the zero potential terminal of the overcharge and discharge protection device (e.g., a circuit board). The output terminal of the first operational amplifier A1 is grounded through the first capacitor C1, and the first capacitor C1 constitutes a low-pass filter, which may be used to filter out the voltage signal output by the output terminal of the first operational amplifier A1 (the positive output terminal of the collector). The capacitance value of the first capacitor C1 may be selected according to actual needs. Since the voltage of the battery changes little during the charging and discharging process, the capacitance value of the first capacitor C1 can be small enough to avoid eliminating the change rate of the collected battery voltage.

[0046] In an embodiment of the present application, the differentiator may include a second capacitor C2, a second operational amplifier and a first resistor R1. The positive and negative output terminals of the collector are electrically connected to the positive and negative input terminals of the differentiator, respectively. Specifically, the first end of the second capacitor C2 is electrically connected to the output terminal of the first operational amplifier A1, and the second end is electrically connected to the inverting input terminal of the second operational amplifier A2. The first end of the second capacitor C2 can be used as the positive input terminal of the differentiator. The negative input terminal of the differentiator is electrically connected to the zero potential terminal. The first resistor R1 is connected in series to the feedback loop between the output terminal of the second operational amplifier A2 and the in-phase input terminal, and the output terminal of the second operational amplifier A2 can be used as the positive output terminal of the differentiator, and the negative output terminal of the differentiator can be electrically connected to the negative power supply (not shown in the figure) and the zero potential terminal of the second operational amplifier A2. The ratio of the output voltage of the differentiator to the input voltage is:

[0047]

[0048] Among them, V o1 is the output voltage of the differentiator, V i1is the input voltage of the differentiator, R1 is the resistance value of the first resistor R1, and C2 is the capacitance value of the second capacitor C2.

[0049] Since the differentiator input voltage V i1 That is, the battery voltage value collected by the collector, and its change speed is extremely small before entering the overcharge or overdischarge stage, so the gain of the differentiator (-R1C2) needs to be high to reflect the battery voltage change. Since the input current of the differentiator can be calculated by the following formula:

[0050]

[0051] Among them I i1 is the differentiator input current, j is a complex unit, and ω is the angular frequency.

[0052] Therefore, when the gain value of the differentiator is determined, it is preferred to take a high resistance value R1 and a low capacitance value C2 to reduce the input current of the differentiator and reduce the overall power consumption of the device. However, there is leakage current at the input end of the second operational amplifier A2, which will cause an error in the amplification factor. Therefore, the values ​​of R1 and C2 should also make the input current much larger than the leakage current of the second operational amplifier A2. In the embodiment of the present application, the resistance value of the first resistor R1 ranges from 1000 to 10000 ohms, and the capacitance value of the second capacitor C2 ranges from 100nF to 1000nF.

[0053] Although in Figure 1 In the embodiment shown, no filter is provided at the output end of the differentiator, but in actual application scenarios, a filter can be added according to the specific debugging results, and the positive output end of the differentiator can be grounded (zero potential end) through the filter. The filter can be a low-pass filter for filtering out the noise generated by the differentiator.

[0054] In an embodiment of the present application, the delay function of the delayer can be realized by the controllable switch SW1 and the third capacitor C3. Examples of the controllable switch SW1 may include MOS tubes, triodes (BJTs), etc. Since the differentiator gain is a negative number, the connection of the controllable switch SW1 needs to pay attention to the unidirectional blocking capability of the device. For example, the controllable switch SW1 can be an NMOS tube, then its drain is the first end of the controllable switch SW1 (i.e., the positive input end of the delayer), and the source is the second end of the controllable switch SW1, which can be grounded (zero potential end) through the third capacitor C3. The negative input end and the negative output end (not shown in the figure) of the delayer can be connected to the zero potential end.

[0055] The on and off of the controllable switch SW1 can be controlled by a PWM signal. The overcharge and discharge protection device can include a PWM signal generator. In one example, the overcharge and discharge protection device can include a processor, such as a single chip microcomputer, a microcontroller, a programmable logic device (such as an FPGA), etc., which can be used as a PWM signal generator to generate a PWM signal.

[0056] When the controllable switch SW1 is turned on, the voltage signal at the second end is updated to the voltage signal at the first end (the positive input end of the delayer). When the controllable switch SW1 is turned off, the third capacitor C3 retains the voltage value updated most recently (the last time the controllable switch SW1 was turned on), and continues until the next time the controllable switch SW1 is turned on. Therefore, the value of the capacitance of the third capacitor C3 should take into account the cycle of the control signal (PWM signal) of the controllable switch SW1. If the cycle of the PWM signal is relatively long, the third capacitor C3 should select a large capacitance value to reduce the attenuation that may occur when the voltage is stored. The controllable switch SW1 should be selected so that the source-drain parasitic capacitance is much smaller than the capacitance value of the third capacitor C3 to reduce the impact of the voltage change at the input end of the delayer on the stored voltage. According to the actual application, the cycle of the PWM signal can be set to seconds or minutes (for example, 10 seconds to 1 minute), but the duty cycle of the PWM signal can be adjusted according to the capacitance value of the third capacitor C3. If the capacitance of the third capacitor C3 is larger, the duty cycle increases accordingly, so that there is sufficient time to update the voltage stored in the third capacitor C3. In other words, the capacitance of the third capacitor C3 is positively correlated with the period of the PWM signal, and the duty cycle of the PWM signal is positively correlated with the capacitance of the third capacitor C3.

[0057] The voltage stored in the third capacitor C3 also needs to be amplified by a certain multiple. This is because the battery voltage change rate (slope) does not change much over time under normal operating conditions. Taking into account the measurement error, the past historical battery voltage slope needs to be amplified by a certain multiple to ensure that the current battery voltage slope changes significantly compared to the past historical battery voltage slope. In this embodiment, the amplification of the historical battery voltage slope can be achieved by a non-inverting amplifier composed of a third operational amplifier A3. A second resistor R2 is connected in series between the inverting input terminal and the output terminal of the third operational amplifier A3, and the inverting input terminal is connected to the zero potential terminal through the third resistor R3, so the amplification factor can be calculated by the following formula:

[0058]

[0059] Where V o2 is the output voltage of the non-inverting amplifier (third operational amplifier A3), V i2 is the input voltage of the non-inverting amplifier (ie, the storage voltage of the third capacitor C3). The value of is the magnification. In one example, the magnification may be greater than 2.

[0060] The signal output from the positive output terminal of the differentiator is electrically connected to the non-inverting input terminal of the comparator A4, representing the opposite number of the current battery voltage change (slope) value; the signal output from the positive output terminal of the differentiator is also electrically connected to the positive input terminal of the delay device (the first end of the controllable switch SW1).

[0061] The output terminal of the third operational amplifier A3 is connected to the inverting input terminal of the comparator A4, and represents the opposite number of the battery voltage change (slope) value in the past history.

[0062] When the battery enters the overcharge or overdischarge stage, the battery voltage changes rapidly. At this time, the current battery voltage change (slope) will rapidly exceed the past historical battery voltage change (slope). At the input port of comparator A4, the inverse of the current battery voltage change rate (slope) will be much lower than the inverse of the past historical battery voltage change (slope). At this time, comparator A4 outputs a high-level signal, which is an early warning signal. The early warning signal can be output to the processor, and the processor can perform an alarm action when receiving the early warning signal, such as controlling a buzzer to sound, or controlling a light alarm to emit light, etc.

[0063] The above scheme provided by the embodiment of the present application collects the battery voltage in real time through the collector, and the collected battery voltage is connected to the differentiator through the filter to obtain the battery voltage change slope, and the past historical battery voltage slope is retained through the delay device, and then the two slope values ​​are compared. When the real-time voltage slope is greater than the past historical slope, the comparator A4 outputs a high-level signal to form an early warning. The scheme is simple to implement and can accurately realize early warning based on the voltage change characteristics of lithium-ion energy storage batteries in the overcharging and over-discharging stages.

[0064] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0065] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. An overcharge and discharge protection device for an energy storage battery, characterized in that: include: A signal collector is configured to collect a battery voltage of a battery to be tested and filter the battery voltage; a differentiator, electrically connected to the signal collector, configured to receive the battery voltage, perform a differential operation on the battery voltage, and output a slope signal reflecting a rate of change of the battery voltage; A delayer, comprising a controllable switch, a third capacitor, a third operational amplifier, a second resistor and a third resistor, wherein the first end of the controllable switch is electrically connected to the output end of the differentiator and serves as the positive input end of the delayer, the second end of the controllable switch is grounded through the third capacitor, the second end of the controllable switch is also electrically connected to the non-inverting input end of the third operational amplifier, the output end of the third operational amplifier serves as the positive output end of the delayer, and the inverting input end of the third operational amplifier is grounded through the second resistor and connected to the output end of the third operational amplifier through the third resistor; A comparator, wherein the positive input terminal and the negative input terminal of the comparator are electrically connected to the positive output terminal and the negative output terminal of the delayer respectively, and the comparator is configured to output a warning signal when the battery to be tested is in an overcharge or overdischarge stage.

2. The overcharge and discharge protection device according to claim 1, characterized in that: Also includes: A PWM signal generator is used to output a PWM signal to the controllable switch.

3. The overcharge and discharge protection device according to claim 2, characterized in that: The capacitance value of the third capacitor is positively correlated with the period of the PWM signal, and the duty cycle of the PWM signal is positively correlated with the capacitance value of the third capacitor.

4. The overcharge and discharge protection device according to claim 1, characterized in that: The resistance value of the second resistor and the resistance value of the third resistor satisfy the following relationship: Wherein, R2 is the resistance value of the second resistor, and R3 is the resistance value of the third resistor.

5. The overcharge and discharge protection device according to claim 1, characterized in that: The signal collector comprises: A first operational amplifier and a first capacitor, wherein the non-inverting input terminal of the first operational amplifier is electrically connected to the positive electrode of the battery to be tested, the inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the first operational amplifier, the output terminal of the operational amplifier is grounded through the first capacitor, and the first capacitor is used as a low-pass filter.

6. The overcharge and discharge protection device according to claim 5, characterized in that: The differentiator comprises: a second capacitor, a second operational amplifier and a first resistor, wherein the first end of the second capacitor is electrically connected to the output end of the first operational amplifier, the second end of the second capacitor is electrically connected to the inverting input end of the second operational amplifier, the non-inverting input end of the second operational amplifier is electrically connected to the output end of the second operational amplifier through the first resistor, and the output end of the second operational amplifier is electrically connected to the first end of the controllable switch as the output end of the differentiator.

7. The overcharge and discharge protection device according to claim 6, characterized in that: The resistance value of the first resistor ranges from 1000 to 10000 ohms, and the capacitance value of the second capacitor ranges from 100 nF to 1000 nF.

8. The overcharge and discharge protection device according to claim 6, characterized in that: The differentiator further comprises a low-pass filter, and the output end of the differentiator is grounded through the low-pass filter.

9. The overcharge and discharge protection device according to claim 1, characterized in that: The controllable switch is an NMOS tube, the drain of the NMOS tube is the first end of the controllable switch, and the source is the second end of the controllable switch.

10. The overcharge and discharge protection device according to claim 1, characterized in that: The overcharge and discharge protection device is integrated on a circuit board.

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