An ultrasonic-based battery module monitoring system and method

Abstract

The application provides a battery module monitoring system and method based on ultrasonic waves, and the system comprises at least one ultrasonic signal transceiving unit, the ultrasonic signal transceiving unit is arranged correspondingly to a battery to be measured; a signal conditioning module, the signal conditioning module comprises a charge amplification unit, an instrument amplification unit, a filter unit and a detector unit; an analog-to-digital conversion module, the analog-to-digital conversion module is used for AD collection of the ultrasonic waves after envelope detection, so as to obtain a digital ultrasonic signal; and a main control unit, which is used for determining an ultrasonic characteristic parameter according to the digital ultrasonic signal and determining the health state of the battery to be measured according to the change value of the ultrasonic characteristic parameter. The application determines the health state of the battery to be measured based on the change value of the ultrasonic characteristic parameter, after the peak envelope of the ultrasonic waves is obtained by processing the ultrasonic waves, only the peak envelope of the ultrasonic waves needs to be collected, the instantaneous value of the ultrasonic waves does not need to be collected, the requirement for the conversion speed of the AD collection device is greatly reduced, and the cost of the battery module monitoring system is reduced.

Description

Technical Field

[0001] This application relates to the field of battery module monitoring technology, specifically to an ultrasonic-based battery module monitoring system and method. Background Technology

[0002] With the development of technology, new energy vehicles are becoming more and more popular. As the core power component of new energy vehicles, batteries are prone to instability in vehicle operation and accidents if damaged. Therefore, real-time monitoring of battery health is particularly important.

[0003] Current vehicle battery management systems typically estimate the battery's state of charge and health by monitoring external parameters such as voltage, current, and temperature. However, this approach lacks high monitoring accuracy. The feasibility of ultrasound-based battery module monitoring solutions has been verified. These solutions estimate battery state by analyzing the characteristic parameters of the ultrasonic signals emitted by the battery. Currently, there are two main ultrasound-based battery module monitoring solutions: one uses a dedicated ultrasonic pulse generator and receiver to excite the ultrasonic probe, connecting an oscilloscope and data acquisition card to the ultrasonic signal receiver to acquire the ultrasonic signals. However, this solution involves expensive equipment and a bulky monitoring system, limiting its use to laboratory settings and making it unsuitable for real-time monitoring in practical applications such as new energy vehicles. The other solution uses highly integrated devices like STM32 and FPGA to construct an ultrasonic data acquisition system. The STM32 control circuit excites the ultrasonic probe to emit ultrasonic signals, and the FPGA acquires and analyzes the high-frequency ultrasonic signals in real time. Based on the ultrasonic characteristic parameters, the system determines the battery's SOC and state of charge, thus assessing its health. However, this solution requires acquiring instantaneous values ​​of high-frequency ultrasonic signals, placing high demands on the conversion speed of the AD acquisition device. This necessitates the use of a high-performance FPGA, leading to a relatively high system cost and presenting cost issues in practical applications. Summary of the Invention

[0004] The main objective of this application is to propose an ultrasonic-based battery module monitoring system and method. By setting a signal conditioning module between the ultrasonic receiver and the AD acquisition device, the ultrasonic waves received by the ultrasonic receiver are converted into voltage signals, and then the ultrasonic waves are amplified, filtered, and envelope detected. The AD acquisition device acquires the peak envelope of the ultrasonic waves, and then determines the ultrasonic characteristic parameters based on the acquired digital ultrasonic signals. Based on the changes in the ultrasonic characteristic parameters, the health status of the battery under test is determined. Thus, this application only needs to acquire the ultrasonic envelope and sense the changing trend of the ultrasonic characteristic parameters, which greatly reduces the requirements for the conversion speed of the AD acquisition device and reduces the cost of the battery module monitoring system while ensuring the monitoring performance of the battery module monitoring system.

[0005] The first aspect of this application provides an ultrasonic-based battery module monitoring system for monitoring the health status of a battery module, the battery module including at least one battery to be tested, and the system comprising:

[0006] An ultrasonic module includes at least one ultrasonic signal transceiver unit, which is correspondingly configured with the battery under test. The ultrasonic signal transceiver unit includes an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic receiver is used to receive ultrasonic waves, which are formed by the ultrasonic signal emitted by the corresponding ultrasonic transmitter propagating on the surface of the battery under test.

[0007] A signal conditioning module is connected to each of the ultrasound receivers. The signal conditioning module includes a charge amplification unit, an instrument amplification unit, a filtering unit, and a detection unit connected in sequence. The charge amplification unit is used to amplify the ultrasound received by the ultrasound receiver and convert the ultrasound from a charge signal to a voltage signal. The instrument amplification unit is used to amplify the ultrasound after it has been converted to a voltage signal. The filtering unit is used to filter out the harmonic components in the ultrasound. The detection unit is used to perform envelope detection on the ultrasound after the harmonics have been filtered out to obtain the peak envelope of the ultrasound.

[0008] An analog-to-digital conversion module is used to perform AD acquisition on the peak envelope of the ultrasonic wave to obtain a digital ultrasonic signal;

[0009] The main control unit is connected to the analog-to-digital conversion module and is used to receive the digital ultrasonic signal output by the analog-to-digital conversion module. The main control unit is also used to determine ultrasonic characteristic parameters based on the digital ultrasonic signal and to determine the health status of the battery under test based on the change value of the ultrasonic characteristic parameters.

[0010] In some embodiments, the ultrasound-based battery module monitoring system further includes: a plurality of excitation units, each excitation unit being configured in a one-to-one correspondence with an ultrasonic transmitter, each excitation unit being configured to output an excitation signal to the corresponding ultrasonic transmitter, so that the ultrasonic transmitter receiving the excitation signal transmits the ultrasonic signal, each excitation unit being connected to the main control unit, and the main control unit being configured to control the excitation units to be turned on sequentially so that the plurality of ultrasonic transmitters sequentially transmit the ultrasonic signal.

[0011] In some embodiments, the ultrasound-based battery module monitoring system further includes: a multiplexer connected between the signal conditioning module and each of the ultrasound receivers, the multiplexer being used to control the on / off state of each of the ultrasound receivers, the multiplexer being connected to the main control unit, and the main control unit being used to control each channel of the multiplexer to be sequentially turned on so that the multiple ultrasound receivers sequentially transmit the received ultrasound waves to the signal conditioning module.

[0012] In some embodiments, the charge amplification unit includes a first operational amplifier unit, a first input terminal of the first operational amplifier unit connected to the ultrasonic receiver, a second input terminal of the first operational amplifier unit grounded, an output terminal of the first operational amplifier unit connected to the input terminal of the instrumentation amplification unit, a first capacitor connected between the input terminal of the first operational amplifier unit and the ultrasonic receiver, and the charge amplification unit further includes a first resistor and a second capacitor, one end of the first resistor connected to the output terminal of the first operational amplifier unit, the other end of the first resistor connected to the first input terminal of the first operational amplifier unit, and the second capacitor and the first resistor connected in parallel between the output terminal and the first input terminal of the first operational amplifier unit.

[0013] In some embodiments, the instrumentation amplification unit includes a second operational amplifier unit, the first input terminal of the second operational amplifier unit is connected to the output terminal of the charge amplification unit, the second input terminal of the second operational amplifier unit is grounded, a gain adjustment resistor is connected between the two gain adjustment pins of the second operational amplifier unit, and the first and second output terminals of the second operational amplifier unit are connected to the input terminal of the filter unit.

[0014] In some embodiments, the filtering unit includes a non-inverting amplifier, the input of which is connected to the output of the instrumentation amplifier unit. A third capacitor and a second resistor are connected sequentially between the output of the instrumentation amplifier unit and the input of the non-inverting amplifier. A fourth capacitor and a third resistor are bypassed between the second resistor and the input of the non-inverting amplifier and then grounded. The third capacitor and the third resistor constitute a first-order passive high-pass filter circuit, and the second resistor and the fourth capacitor constitute a first-order passive low-pass filter circuit. The output of the non-inverting amplifier is connected to the input of the detector unit. The output of the non-inverting amplifier is also connected to the feedback input of the non-inverting amplifier. A fourth resistor is connected between the output of the non-inverting amplifier and the feedback input.

[0015] In some embodiments, the detection unit includes: an envelope detection chip, a first rectifier diode, a second rectifier diode, a fifth capacitor, a sixth capacitor, a variable resistor unit, and a fifth resistor. The envelope detection chip is composed of a third operational amplifier unit and a fourth operational amplifier unit. The first terminal of the first rectifier diode is connected to the output terminal of the third operational amplifier unit, the second terminal of the third operational amplifier unit is connected to the inverting input terminal of the third operational amplifier unit, the second terminal of the first rectifier diode is connected to the first fixed terminal of the variable resistor unit, the first terminal of the first rectifier diode is connected to the first terminal of the second rectifier diode, the first rectifier diode is also connected in parallel with the sixth capacitor, the sliding terminal of the variable resistor unit is connected to the second terminal of the second rectifier diode, the second rectifier diode is connected to the first terminal of the fifth capacitor, the second terminal of the fifth capacitor is grounded, the fifth capacitor is also connected in parallel with the fifth resistor to form an RC circuit, the second terminal of the second rectifier diode is also connected to the non-inverting input terminal of the fourth operational amplifier unit, the inverting input terminal of the fourth operational amplifier unit is connected to the output terminal of the fourth operational amplifier unit, and the output terminal of the fourth operational amplifier unit is connected to the analog-to-digital conversion module and the sliding terminal of the variable resistor unit, respectively.

[0016] An ultrasonic-based battery module monitoring method, applied to an ultrasonic-based battery module monitoring system as described in any one of the first aspect embodiments, the method comprising:

[0017] Each of the ultrasonic receivers is turned on sequentially so that it receives ultrasonic waves, wherein the ultrasonic waves are formed by the ultrasonic signal emitted by the ultrasonic transmitter corresponding to the ultrasonic receiver and then propagating on the surface of the battery under test.

[0018] Each of the ultrasonic transmitters is controlled to sequentially transmit the ultrasonic signal;

[0019] The ultrasonic wave is amplified by charge and converted from a charge signal to a voltage signal;

[0020] The ultrasonic wave, after being converted into a voltage signal, is amplified for instrumental use to obtain an instrumental ultrasonic signal.

[0021] The instrument's ultrasonic signal is bandpass filtered to obtain a filtered ultrasonic signal;

[0022] Envelope detection is performed on the filtered ultrasonic signal to obtain the peak envelope of the ultrasonic wave;

[0023] The peak envelope of the ultrasonic wave is acquired by AD acquisition to obtain the digital ultrasonic signal;

[0024] Determine the ultrasonic characteristic parameters based on the digital ultrasonic signal;

[0025] The health status of each battery under test is determined based on the ultrasonic characteristic parameters.

[0026] In some embodiments, the step of performing AD acquisition on the peak envelope of the ultrasound wave to obtain the digital ultrasound signal includes:

[0027] Data is collected on the peak envelopes of multiple ultrasonic waves received by the ultrasonic receiver within the same sampling period.

[0028] The average value of the peak envelopes of multiple ultrasound waves acquired by the same ultrasound receiver within the same sampling period is calculated to obtain the digital ultrasound signal of the ultrasound receiver within the corresponding sampling period.

[0029] In some embodiments, the ultrasonic characteristic parameters include time of flight, energy integral, and waveform index, and determining the health status of each battery under test based on the ultrasonic characteristic parameters includes:

[0030] The changes in flight time, energy integral, and waveform exponent of two consecutive digital ultrasonic signals corresponding to the same battery under test are compared with the corresponding reference intervals.

[0031] If at least one of the changes in flight time, energy integral, and waveform index is not within the corresponding reference interval, the health status of the battery under test is determined to be damaged.

[0032] This application proposes an ultrasonic-based battery module monitoring system and method. The system includes: an ultrasonic module, comprising at least one ultrasonic signal transceiver unit, wherein the ultrasonic signal transceiver unit is correspondingly configured with the battery under test, and the ultrasonic signal transceiver unit includes an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic receiver is used to receive ultrasonic waves, which are formed by the ultrasonic signal emitted by the corresponding ultrasonic transmitter propagating on the surface of the battery under test; and a signal conditioning module, connected to each ultrasonic receiver. The signal conditioning module includes a charge amplification unit, an instrumentation amplification unit, a filtering unit, and a detection unit connected in sequence. The charge amplification unit is used to amplify the ultrasonic waves received by the ultrasonic receiver and filter them. The ultrasonic wave is converted from a charge signal to a voltage signal. The instrument amplification unit amplifies the converted ultrasonic wave signal. The filtering unit filters out harmonic components from the ultrasonic wave. The detection unit performs envelope detection on the ultrasonic wave after harmonic removal. An analog-to-digital conversion module performs AD acquisition on the envelope-detected ultrasonic wave to obtain a digital ultrasonic signal. A main control unit is connected to the analog-to-digital conversion module and receives the digital ultrasonic signal output by the analog-to-digital conversion module. The main control unit also determines ultrasonic characteristic parameters based on the digital ultrasonic signal and determines the health status of the battery under test based on the changes in the ultrasonic characteristic parameters. This application incorporates a signal conditioning module between the ultrasonic receiver and the AD acquisition device. The ultrasonic waves received by the receiver are amplified by a dedicated charge amplification unit, converting the ultrasonic waves from a charge signal to a voltage signal. The amplified and voltage-converted ultrasonic waves are then amplified and filtered. Finally, envelope detection is performed on the amplified and filtered ultrasonic waves. The AD acquisition device only needs to acquire the peak envelope of the ultrasonic waves to obtain a digital ultrasonic signal. This digital ultrasonic signal is then analyzed to determine the corresponding ultrasonic characteristic parameters. The battery's health status is determined based on the changes in these ultrasonic characteristic parameters. Therefore, this embodiment judges the battery's health status by the amplitude of changes in ultrasonic characteristic parameters. To assess the health status of a battery, the ultrasonic signal acquisition only needs to ensure that the acquired signal is sufficient to reflect the changing trends of the ultrasonic characteristic parameters. Based on this, this application only requires pre-amplification, filtering, and envelope detection of the ultrasonic wave, followed by acquisition of the peak envelope of the ultrasonic wave via an AD acquisition device and conversion of the envelope into a corresponding digital ultrasonic signal. Compared to the existing technology that acquires high-frequency ultrasonic signals in real time and determines the battery's SOC and state of charge in real time based on the high-frequency ultrasonic signals to judge the battery's health status, this significantly reduces the requirements for the conversion speed of the AD acquisition device. While ensuring the function of monitoring the battery's health status, it can effectively reduce the cost of the battery module monitoring system.

[0033] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the modular structure of an ultrasonic-based battery module monitoring system provided in one embodiment of this application;

[0035] Figure 2 This is a circuit diagram of an excitation unit provided in one embodiment of this application;

[0036] Figure 3 This is a circuit diagram of a charge amplification unit provided in one embodiment of this application;

[0037] Figure 4 This is a circuit diagram of an instrumentation amplifier unit provided in one embodiment of this application;

[0038] Figure 5 This is a circuit diagram of a filtering unit provided in one embodiment of this application;

[0039] Figure 6 This is a circuit diagram of a detection unit provided in one embodiment of this application;

[0040] Figure 7 It is an application Figure 6 The waveforms of the ultrasonic wave before and after envelope detection by the detection unit are shown.

[0041] Figure 8 This is a flowchart of an ultrasonic-based battery module monitoring method provided in one embodiment of this application;

[0042] Figure 9 This is a schematic diagram illustrating the change in the energy integral coefficient when a battery exhibits gas production, provided in one embodiment of this application.

[0043] Figure 10 This is a schematic diagram illustrating the change in the energy integral coefficient when a battery leaks, according to one embodiment of this application.

[0044] Figure 11 yes Figure 7 Sub-flowchart of step S801;

[0045] Figure 12 yes Figure 7 Sub-flowchart of step S807;

[0046] Figure 13 yes Figure 7 Sub-flowchart of step S809;

[0047] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0049] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0051] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0052] Reference Figure 1 The first aspect of this application proposes an ultrasonic-based battery module monitoring system. The system is used to monitor the health status of a battery module, which includes at least one battery to be tested. The system includes:

[0053] The ultrasonic module 101 includes at least one ultrasonic signal transceiver unit. The ultrasonic signal transceiver unit and the battery under test are correspondingly arranged. The ultrasonic signal transceiver unit includes an ultrasonic transmitter 102 and an ultrasonic receiver 103. The ultrasonic receiver 103 is used to receive ultrasonic waves. The ultrasonic waves are formed after the ultrasonic signals emitted by the corresponding ultrasonic transmitter 102 propagate on the surface of the battery under test.

[0054] The signal conditioning module 104 is connected to each ultrasound receiver 103. The signal conditioning module 104 includes a charge amplification unit 105, an instrument amplification unit 106, a filtering unit 107, and a detection unit 108 connected in sequence. The charge amplification unit 105 is used to amplify the ultrasound received by the ultrasound receiver 103 and convert the ultrasound from a charge signal to a voltage signal. The instrument amplification unit 106 is used to amplify the ultrasound after it has been converted to a voltage signal. The filtering unit 107 is used to filter out the harmonic components in the ultrasound. The detection unit 108 is used to perform envelope detection on the ultrasound after the harmonics have been filtered out to obtain the peak envelope of the ultrasound.

[0055] Analog-to-digital conversion module 109 is used to perform AD acquisition on the ultrasonic waves after envelope detection to obtain digital ultrasonic signals;

[0056] The main control unit 110 is connected to the analog-to-digital converter module 109 and is used to receive the digital ultrasonic signal output by the analog-to-digital converter module 109. The main control unit 110 is also used to determine the ultrasonic characteristic parameters based on the digital ultrasonic signal and to determine the health status of the battery under test based on the change value of the ultrasonic characteristic parameters.

[0057] In some embodiments, the ultrasonic transmitter 102 can be an ultrasonic transducer. Specifically, the ultrasonic transducer can be composed of a piezoelectric ceramic wafer. After applying an electric field excitation to the piezoelectric ceramic wafer, the piezoelectric ceramic wafer will generate mechanical vibration in response to the electric field excitation, thereby generating ultrasonic waves that are emitted outward. Specifically, in this embodiment, referring to the prior art, a specific electric field excitation can be applied to multiple piezoelectric ceramic wafers in a set order through a dedicated STM32 circuit, so that multiple piezoelectric ceramic wafers emit ultrasonic signals in sequence. In some preferred embodiments, the main control unit 110 can also control the excitation unit to output excitation signals to the ultrasonic transmitter 102 in sequence, so that multiple ultrasonic transmitters 102 emit ultrasonic signals in response to the excitation signals in sequence.

[0058] In some embodiments, the ultrasonic receiver 103 is also an ultrasonic transducer, namely a piezoelectric ceramic wafer. When subjected to the mechanical stress of ultrasonic waves, the piezoelectric ceramic wafer undergoes slight deformation, resulting in a change in the crystal structure of the piezoelectric ceramic wafer and causing a change in the charge distribution. This converts the received ultrasonic waves into corresponding charge signals, thus obtaining ultrasonic waves. Specifically, the ultrasonic transmitter 102 and ultrasonic receiver 103 corresponding to the same battery under test can be located on opposite sides of the battery under test, or installed on the same side of the battery under test. Understandably, to avoid interference caused by the overlapping operation of ultrasonic transceiver units corresponding to different batteries under test, in this embodiment, the main control unit 110 can control multiple ultrasonic transceiver units to operate sequentially. That is, the main control unit 110 can output an excitation signal to only one transmitter at a time, causing the ultrasonic transmitter 102 that receives the excitation signal to emit an ultrasonic signal. At the same time, only the ultrasonic receiver 103 corresponding to the ultrasonic transmitter 102 that emits the ultrasonic signal can transmit the received ultrasonic wave to the signal conditioning module 104 for conditioning, while the connection between the other ultrasonic receivers 103 and the signal conditioning module 104 is disconnected. Based on this, interference between multiple ultrasonic transceiver units is avoided. It should be noted that in this embodiment, the ultrasonic wave can be the ultrasonic signal emitted by the ultrasonic transmitter 102 that propagates along the battery under test to the corresponding ultrasonic receiver 103, and the charge signal formed by the ultrasonic receiver 103 in response to the ultrasonic signal after receiving the ultrasonic signal.

[0059] In some embodiments, the signal conditioning module 104 includes a charge amplification unit 105, an instrumentation amplification unit 106, a filtering unit 107, and a detection unit 108 connected in sequence. Specifically, the output terminal of the ultrasound receiver 103 is connected to the input terminal of the charge amplification unit, the output terminal of the charge amplification unit 105 is connected to the input terminal of the instrumentation amplification unit 106, the input terminal of the instrumentation amplification unit 106 is connected to the input terminal of the filtering unit 107, and the output terminal of the filtering unit 107 is connected to the input terminal of the detection unit 108. In this embodiment, the ultrasonic receiver 103 is a piezoelectric ceramic wafer. It undergoes slight deformation by sensing the mechanical vibration caused by the ultrasonic waves emitted by the ultrasonic transmitter 102, generating a charge signal using the piezoelectric effect. However, the charge signal generated by the piezoelectric effect is generally very weak and cannot be directly amplified by conventional instrumentation amplifiers. Therefore, a charge amplification unit 105 is first connected to the output of the ultrasonic receiver 103 to initially amplify the ultrasonic waves. Simultaneously, utilizing the integration effect of the capacitor, the charge signal can be converted into a voltage signal. After the initial amplification and integration of the ultrasonic waves by the charge amplification unit 105, a voltage signal with an amplitude reaching tens of millivolts can be obtained. This voltage signal is then input to the instrumentation amplification unit 106 for secondary amplification, further increasing its amplitude and reducing the influence of background noise on the signal. It is also easier for the AD acquisition device to acquire. Furthermore, as the ultrasonic waves are amplified, the difference between two adjacent ultrasonic waves from the same battery under test is also amplified, which is more helpful in subsequently judging the health status of the battery under test based on the changes in ultrasonic characteristic parameters. After the ultrasonic wave is amplified a second time by the instrumentation amplification unit 106, it is then bandpass filtered by the filtering unit 107 to remove low-frequency and high-frequency noise, retaining only the effective frequency band. Following filtering, the ultrasonic wave is envelope-detected to obtain its peak envelope, which reflects the amplitude variation. The AD acquisition device acquires this peak envelope to obtain a set of digital ultrasonic signals reflecting the amplitude variation, eliminating the need to acquire the instantaneous value of the ultrasonic wave. This significantly reduces the conversion speed requirement of the AD acquisition device. In this case, a conventional analog-to-digital converter can meet the requirements, eliminating the need for high-performance AD ​​acquisition devices such as FPGAs, effectively reducing the cost of the battery module monitoring system.

[0060] Understandably, the analog-to-digital conversion module 109 is used to perform AD acquisition on the peak envelope of the ultrasound wave to obtain multiple sampling points. The data of these sampling points constitute the digital ultrasound signal corresponding to the ultrasound wave. The analog-to-digital conversion module 109 is also connected to the main control unit 110 to transmit the digital ultrasound signal to the main control unit 110.

[0061] After receiving the digital ultrasonic signal, the main control unit 110 can determine the corresponding ultrasonic characteristic parameters based on the signal. Specifically, the ultrasonic characteristic parameters may include the time of flight of the ultrasonic wave, the energy integral of the ultrasonic wave, and the waveform index of the ultrasonic wave. The main control unit 110 will determine whether the battery under test is damaged based on the change values ​​of the ultrasonic characteristic parameters of two adjacent sets of digital ultrasonic signals corresponding to the same battery under test. Specifically, when the change value between the ultrasonic characteristic parameters of two adjacent sets of digital ultrasonic signals of the same battery under test is greater than a given reference range, the battery under test can be considered damaged. In this embodiment, the main control unit 110 can use a 51 series microcontroller. It is understood that the 51 series microcontroller has a lower cost, and using a 51 series microcontroller as the main control unit 110 can effectively reduce the cost of the battery module monitoring system.

[0062] Understandably, the main control unit 110 can also communicate with a host computer via a CAN bus. The host computer can be the control module of the battery module installation equipment. For example, if the battery module is the power source of a new energy vehicle, the host computer can be the vehicle's infotainment system. The main control unit 110 can report the health status of the battery module to the host computer via the CAN bus so that the host computer can output prompt information based on the health status of the battery module.

[0063] In some embodiments, the ultrasonic-based battery module monitoring system further includes: multiple excitation units, each corresponding to an ultrasonic transmitter 102. Each excitation unit outputs an excitation signal to its corresponding ultrasonic transmitter 102, causing the ultrasonic transmitter 102 receiving the excitation signal to transmit an ultrasonic signal. Each excitation unit is connected to a main control unit 110, which controls the excitation units to sequentially activate, causing the multiple ultrasonic transmitters 102 to sequentially transmit ultrasonic signals. Specifically, refer to... Figure 2Each excitation unit includes a switching transistor Q1 and multiple resistors. The ultrasonic transmitter 102 corresponding to the excitation unit and the multiple resistors are connected in parallel between the power supply and the emitter of the switching transistor Q1. It can be understood that the parallel resistors limit the current passing through the ultrasonic transmitter 102 to prevent excessive current from damaging the ultrasonic transmitter 102. The base of the switching transistor Q1 is connected to the main control unit 110, and the collector of the switching transistor Q1 is grounded. When the main control unit 110 outputs a high level to the base of the switching transistor Q1, the switching transistor Q1 is turned on, and the potential difference across the ceramic wafer becomes a high voltage. When the main control unit 110 outputs a low level to the base of the switching transistor Q1, the switching transistor Q1 is turned off, and the potential difference across the ceramic wafer becomes 0 volts. Based on this, by outputting a periodic control signal by the main control unit 110, the potential difference across the piezoelectric ceramic wafer can be switched between high voltage and 0 volts to form a square wave excitation. In this embodiment, the pulse width of the square wave excitation can also be adjusted by adjusting the duty cycle of the control signal output by the main control unit 110. In this embodiment, the excitation units and ultrasonic transmitters 102 are configured in a one-to-one correspondence. That is, each excitation unit only sends an excitation signal to its corresponding ultrasonic transmitter 102. Multiple excitation units are connected to the main control unit 110. The main control unit 110 controls the ultrasonic transmitters 102 to send ultrasonic signals sequentially by outputting control signals to each excitation unit in sequence. For example, the battery module may include 16 batteries under test. The ultrasonic module 101 is provided with 16 ultrasonic transmitters 102. An excitation unit is provided between each ultrasonic transmitter 102 and the power supply. The main control unit 110 is provided with 16 output pins, which are respectively connected to the base of the switching transistor Q1 of the 16 excitation units. The main control unit 110 outputs control signals sequentially from the first output pin to the sixteenth output pin and cycles through this process, so that the 16 excitation units sequentially output excitation signals to their corresponding ultrasonic transmitters 102, so that the 16 ultrasonic transmitters 102 send ultrasonic signals sequentially. In this way, the simultaneous operation of multiple ultrasonic transmitters 102 can avoid mutual interference. In this embodiment, the excitation unit consists of a hardware circuit composed of resistors and transistors. The main control unit 110 only needs to output a periodic signal to each transistor in sequence to control the transistor's conduction and cutoff, thereby generating a square wave excitation, which in turn excites the corresponding ultrasonic transmitter 102 to emit an ultrasonic signal. Based on this, the main control unit 110 only needs to control each output pin to output a periodic signal in sequence. Compared with the prior art that uses a dedicated STM32 excitation circuit, the performance requirements of the main control unit 110 are lower, thereby reducing the cost of the battery module monitoring system.

[0064] In some embodiments, a multiplexer is also provided between the multiple ultrasound receivers 103 and the signal conditioning module 104. Specifically, the multiplexer is connected between the ultrasound receivers 103 and the signal conditioning module 104. This multiplexer is used to control the on / off state of the communication link between each ultrasound receiver 103 and the signal conditioning module 104. Specifically, the channels of the multiplexer are configured in a one-to-one correspondence with the ultrasound receivers 103, that is, each ultrasound receiver 103 and the signal conditioning module 104 is provided with one channel of the multiplexer. It can be understood that the multiplexer is also connected to the main control unit 110. The main control unit 110 can control each channel of the multiplexer to be turned on sequentially, so that the multiple ultrasound receivers 103 sequentially transmit the received ultrasound waves to the signal conditioning module 104. Specifically, the multiplexer can be composed of a multiplexer chip, which includes multiple input terminals, a control terminal, and at least one output terminal. The multiple input terminals are respectively connected to the ultrasound receivers 103. The control terminal is connected to the main control unit 110, and the output terminal is connected to the input terminal of the signal conditioning module 104. The main control unit 110 inputs a signal to the control terminal to select the channel to be turned on. Specifically, the main control unit 110 outputs a periodic signal to the control terminal of the multiplexer to control each channel to be turned on sequentially. The ultrasonic receiver 103 connected to the input terminal corresponding to the channel being turned on can transmit the received ultrasonic waves to the signal conditioning module 104. For example, if the battery module includes 16 batteries to be tested, the ultrasonic module 101 is equipped with 16 ultrasonic receivers 103, and the multiplexer includes 16 channels, each channel corresponding to one ultrasonic receiver 103. The main control unit 110 outputs a periodic signal to the control terminal of the multiplexer so that the first to the sixteenth channels of the multiplexer are turned on sequentially. In this way, multiple ultrasonic receivers 103 can be prevented from transmitting the received ultrasonic waves to the signal conditioning module 104 at the same time, thus avoiding interference. It should be noted that the main control unit 110 should control that the ultrasonic receiver 103 corresponding to the channel that is turned on at the same time and the ultrasonic transmitter 102 that receives the excitation signal belong to the same ultrasonic transceiver unit. That is, at the same time, the ultrasonic receiver 103 that is turned on and the ultrasonic transmitter 102 that receives the excitation signal are corresponding to the same battery under test. For example, at a certain time, if the main control unit 110 outputs an excitation signal to the ultrasonic transmitter 102 corresponding to the 10th battery under test, then it should control the multiplexer to turn on the channel between the ultrasonic receiver 103 corresponding to the 10th battery under test and the signal conditioning module 104.

[0065] In some embodiments, refer to Figure 3The charge amplification unit 105 includes: a first operational amplifier unit U1, the first input terminal of the first operational amplifier unit U1 is connected to the ultrasonic receiver 103, the second input terminal of the first operational amplifier unit U1 is grounded, the output terminal of the first operational amplifier unit U1 is connected to the input terminal of the instrumentation amplification unit 106, and a first capacitor C1 is connected between the input terminal of the first operational amplifier unit U1 and the ultrasonic receiver 103. The charge amplification unit 105 also includes a first resistor R1 and a second capacitor C2. One end of the first resistor R1 is connected to the output terminal of the first operational amplifier unit U1, and the other end of the first resistor R1 is connected to the first input terminal of the first operational amplifier unit U1. The second capacitor C2 and the first resistor R1 are connected in parallel between the output terminal and the first input terminal of the first operational amplifier unit U1. In this embodiment, a first capacitor C1 is first connected between the ultrasonic receiver 103 and the first input terminal of the first operational amplifier unit U1. The AC coupling effect of the first capacitor C1 filters out DC noise in the ultrasonic waves output from the ultrasonic output terminal. Then, the ultrasonic waves are input to the first input terminal of the first operational amplifier unit U1. The second input terminal of the first operational amplifier unit U1 is grounded, providing a 0-volt reference voltage to the first operational amplifier unit U1. A first resistor R1 is connected between the output terminal and the first input terminal of the first operational amplifier unit U1 as a feedback resistor. The first resistor R1 is connected in parallel with a second capacitor C2 to form a feedback network. Based on the integral effect of the second capacitor C2, the DC noise in the ultrasonic waves output from the ultrasonic output terminal is filtered out. Ultrasonic waves are converted from charge signals to voltage signals. Simultaneously, an integral negative feedback operational amplifier can be constructed based on this feedback network and the first operational amplifier unit U1. For the charge amplification unit 105, the first resistor R1 and the second capacitor C2 determine the gain of the charge amplification unit 105. The output voltage signal depends on the gain value and the input charge value, i.e., the magnitude of the charge signal generated by the ultrasonic receiver 103 in response to the received ultrasonic signal. Since the resistance value of the first resistor R1 and the capacitance value of the second capacitor C2 are fixed, the voltage signal output by the charge amplification unit 105 is actually proportional to the magnitude of the charge signal input to the ultrasonic receiver 103. In this embodiment, the charge amplification unit 105, composed of the first operational amplifier unit U1, the first resistor R1, the first capacitor C1, and the second capacitor C2, amplifies the ultrasonic waves input to the ultrasonic receiver 103 and converts them into corresponding voltage signals. These signals can then be further conditioned by the signal conditioning module 104 to obtain the corresponding digital ultrasonic signal, thereby analyzing the health status of the battery under test. Specifically, the first operational amplifier unit U1 can be a 3140 chip or other charge amplifier chip; this is not limited in this embodiment. It is understood that, referring to… Figure 3The first operational amplifier unit U1 may also be provided with a bias pin for zeroing, a positive power supply pin and a negative power supply pin for supplying power to the first operational amplifier unit U1, etc. In this embodiment, the first operational amplifier unit U1 with low cost and components such as resistors and capacitors are used to form an instrumentation amplifier to initially amplify the ultrasonic waves and convert the ultrasonic waves from charge signals to voltage signals. This facilitates subsequent signal conditioning of the ultrasonic waves and reduces the performance requirements of the subsequent instrumentation amplification unit 106, filtering unit 107 and detection unit 108, thereby reducing the cost of the ultrasonic-based battery module monitoring system.

[0066] In some embodiments, refer to Figure 4 The instrumentation amplifier unit 106 includes: a second operational amplifier unit U2, the first input terminal of the second operational amplifier unit U2 is connected to the output terminal of the charge amplifier unit 105, the second input terminal of the second operational amplifier unit U2 is grounded, a gain adjustment resistor is connected between the two gain adjustment pins of the second operational amplifier unit U2, and the first and second output terminals of the second operational amplifier unit U2 are connected to the input terminal of the filter unit 107. It is understood that the first input terminal of the second operational amplifier unit U2 is connected to the output terminal of the charge amplification unit 105 to receive the ultrasonic waves after they have been initially amplified and converted into voltage signals by the charge amplification unit 105. The second input terminal of the second operational amplifier unit U2 is grounded, thereby providing a 0-volt reference voltage to the second operational amplifier unit U2. A gain adjustment resistor is connected between the two gain adjustment pins of the second operational amplifier unit U2. This gain adjustment resistor is a variable resistor, such as a sliding rheostat. By adjusting the resistance value of the variable resistor, the gain of the second operational amplifier unit U2 can be adjusted. The second operational amplifier unit U2 includes two output pins, namely a positive voltage output and a negative voltage output. It is understood that the square wave pulse excitation generated by the excitation unit will have a significant impact on the power supply circuit, which will cause a large amplitude pulse noise in the input ultrasonic waves. Therefore, in this embodiment, the large amplitude pulse noise caused by the square wave pulse excitation is filtered out in the ultrasonic waves by bridging two diodes D1 and D2 with opposite directions between the two output pins of the second operational amplifier unit. Specifically, the second operational amplifier unit U2 can use amplifier chips such as AD620 or AD8221, which is not limited in this embodiment. It is understood that the second operational amplifier unit U2 can also be provided with a VDD pin for powering the second operational amplifier unit U2 and a grounded VSS pin. At least one resistor and capacitor can also be connected in series between the input terminal of the second operational amplifier unit U2 and the output terminal of the charge amplification unit 105. The two ends of the capacitor are grounded through a bypass resistor and a bypass capacitor, respectively. The resistor and capacitor between the input terminal of the second operational amplifier unit U2 and the output terminal of the charge amplification unit 105 can form a bandpass filter circuit to perform preliminary bandpass filtering on the output signal of the charge amplification unit 105, filtering out harmonics in the output signal of the charge amplification unit 105.

[0067] In some embodiments, refer to Figure 5 The filtering unit 107 includes a first-order passive low-pass filter circuit, a first-order passive high-pass filter circuit, and a non-inverting proportional amplifier. Specifically, the input terminal of the non-inverting proportional amplifier is connected to the output terminal of the instrumentation amplifier unit 106. A third capacitor C3 and a second resistor R2 are connected sequentially between the output terminal of the instrumentation amplifier unit 106 and the input terminal of the non-inverting proportional amplifier. A fourth capacitor C4 and a third resistor R3 are connected in a bypass manner between the second resistor R2 and the input terminal of the non-inverting proportional amplifier and then grounded. The third capacitor C3 and the third resistor R3 constitute a first-order passive high-pass filter circuit, and the second resistor R2 and the fourth capacitor C4 constitute a first-order passive low-pass filter circuit. The output terminal of the non-inverting proportional amplifier is connected to the input terminal of the detector unit 108. The output terminal of the non-inverting proportional amplifier is also connected to the feedback input terminal of the non-inverting proportional amplifier. A fourth resistor R4 is connected between the output terminal of the non-inverting proportional amplifier and the feedback input terminal. Specifically, the in-phase amplifier can be a TLE2142 series chip. In this embodiment, a first-order passive low-pass filter circuit and a first-order passive high-pass filter circuit are set before the in-phase amplifier unit to filter out high-frequency noise and low-frequency noise in the ultrasonic waves, respectively, retaining only the effective signal in a specific frequency band. The filtered ultrasonic waves are then input into the in-phase amplifier for amplification. In addition, in this embodiment, the filter unit 107 is composed of an in-phase amplifier and a filter circuit consisting of resistors and capacitors, resulting in a lower overall cost. This reduces the cost of the ultrasonic-based battery module monitoring system while maintaining its performance.

[0068] The detection unit 108 can also be implemented using an envelope detection circuit. Specifically, the detection unit 108 can be composed of an envelope detection chip and corresponding peripheral circuits. For example, the envelope detection chip can be a dual operational amplifier chip. In this embodiment, refer to... Figure 6 , Figure 6A hardware circuit diagram of a detection unit 108 is provided. The envelope detection chip consists of a third operational amplifier unit and a fourth operational amplifier unit. It is understood that in this embodiment, the fourth operational amplifier unit is a voltage follower with equal input and output voltages, used to provide current support. The non-inverting input terminal of the third operational amplifier unit is connected to the output terminal of the filter unit 107. A resistor and a grounded bypass capacitor are connected between the non-inverting input terminal of the first operational amplifier unit and the output terminal of the filter unit 107 to form a first-order passive low-pass filter circuit to further filter out high-frequency noise in the output signal of the filter unit. The VDD and VSS pins of the envelope detection chip are... The power supply is connected to the positive and negative terminals to power the third and fourth operational amplifier units. Grounding capacitors can be installed between the VDD and VSS pins and the positive and negative terminals of the power supply to filter out noise in the power input. The peripheral circuit of the envelope detector chip also includes a first rectifier diode D3, a second rectifier diode D4, a first bidirectional transient suppression diode D5, several resistors and capacitors, and a variable resistor unit. Specifically, the first terminal of the first rectifier diode D3 is connected to the output terminal of the third operational amplifier unit, and the second terminal is connected to the inverting input terminal of the third operational amplifier unit. The first rectifier diode D3 is also connected in parallel with the sixth capacitor C6 to form an RC coupling circuit. Transistor D3 is also connected to the first fixed terminal of the variable resistor unit. The second terminal of the first rectifier diode D3 is connected to the first terminal of the second rectifier diode D4. The sliding terminal of the variable resistor unit is connected to the second terminal of the second rectifier diode D4. An eighth resistor R8 can also be connected between the sliding terminal of the variable resistor unit and the second rectifier diode D4 for current limiting protection. The second terminal of the second rectifier diode D4 is also connected to the first terminal of the fifth capacitor C5. The second terminal of the fifth capacitor C5 is grounded. The second terminal of the second rectifier diode D4 is also connected to the non-inverting input terminal of the fourth operational amplifier unit. A connection is also made between the second terminal of the second rectifier diode D4 and the non-inverting input terminal of the fourth operational amplifier unit. A sixth resistor R6 can be connected, and the inverting input and output terminals of the fourth operational amplifier unit are connected. The output terminal of the fourth operational amplifier unit is connected to the sliding terminal of the analog-to-digital converter module and the variable resistor unit, respectively. A seventh resistor R7 is connected between the module conversion module 109 and the output terminal of the fourth operational amplifier unit. A seventh capacitor C7 and a first bidirectional transient suppression diode D5 are connected in parallel to ground and then bypassed to the seventh resistor R7 and the analog-to-digital converter module 109 to prevent transient voltages caused by surges or electrostatic discharge from damaging the analog-to-digital converter module, thereby improving the reliability and stability of the circuit. The fifth capacitor C5 is also connected in parallel with the fifth resistor R5 to form an RC circuit. (Refer to...) Figure 6The envelope detection circuit shown receives filtered ultrasonic waves from the non-inverting input of the third operational amplifier unit. Due to the virtual short circuit of the operational amplifier, pins 2 and 3 of the envelope detection chip, i.e., the non-inverting and inverting inputs of the third operational amplifier unit, have the same waveform. When the value of the ultrasonic wave input from the non-inverting input of the third operational amplifier unit is greater than the voltage of the fifth capacitor C5, i.e., the output voltage of the third operational amplifier unit is greater than the voltage of the fifth capacitor C5, the second rectifier diode D4 conducts while the first rectifier diode D3 is cut off. The ultrasonic wave is then output from the output of the third operational amplifier unit to the non-inverting input of the fourth operational amplifier unit. The analog-to-digital converter module 109 is then output from the non-inverting input of the fourth operational amplifier unit. Meanwhile, since the voltage at the inverting output of the third operational amplifier unit is greater than the voltage at the fifth capacitor C5, there is a voltage drop across the circuit of the variable resistor unit and the eighth resistor R8. Current should flow from the inverting input of the third operational amplifier unit to the fifth capacitor C5. However, due to the virtual open circuit effect of the operational amplifier, the inverting output of the third operational amplifier unit cannot provide current, and the first rectifier diode D3 is also cut off and cannot provide current. At this time, in order to maintain the balance across the circuit of the variable resistor unit and the eighth resistor R8, the third operational amplifier unit charges the fifth capacitor C5. When the ultrasonic wave value begins to decrease, the potential at the inverting input terminal of the third operational amplifier unit is higher than the potential at the non-inverting input terminal, which is higher than the potential at the output terminal of the third operational amplifier unit. At this time, the first rectifier diode D3 is turned on, and the voltage at the output terminal of the third operational amplifier unit is less than the voltage of the fifth capacitor C5. The second rectifier diode D4 is turned off, and the fifth capacitor C5 cannot discharge through the second rectifier diode D4. Meanwhile, in order to maintain the balance across the circuit of the variable resistor unit and the eighth resistor R8, the third operational amplifier unit continuously charges the fifth capacitor C5. When the ultrasonic wave begins to decrease and the third operational amplifier unit stops charging the fifth capacitor C5, the voltage of the fifth capacitor C5 will be at the peak value of the ultrasonic wave. The RC circuit formed by the fifth capacitor C5 and the fifth resistor R5 can control the time required to switch from charging to discharging, thereby keeping the output signal near the peak value for a period of time, achieving peak envelope detection.

[0069] Reference Figure 7 , Figure 7 This is an example of the application of this application. Figure 6 The diagram shows waveforms of the ultrasonic wave before and after envelope detection by the detection unit. Waveform 2 is the ultrasonic wave with a larger amplitude and less noise obtained after charge amplification, instrumentation amplification, and bandpass filtering. Waveform 1 is the waveform obtained after... Figure 6 The waveform diagram shows the peak envelope of waveform 2 obtained after the detection unit performs envelope detection on waveform 2.

[0070] The ultrasonic-based battery module monitoring system proposed in this application embodiment sets up a signal conditioning circuit between the ultrasonic receiver 103 and the analog-to-digital converter module 109. The ultrasonic waves received by the ultrasonic receiver 103 are amplified by charge, amplified by instrumentation, filtered by bandpass, and detected by envelope before signal acquisition. The change value of ultrasonic characteristic parameters is determined based on the peak envelope of the ultrasonic waves, thereby assessing the health status of the battery. Compared with the existing technology that uses high-performance devices such as FPGAs to acquire the instantaneous state of ultrasonic waves to analyze the battery health, this significantly reduces the requirements for the analog-to-digital conversion speed of the AD acquisition device. Thus, digital ultrasonic signals can be acquired by conventional analog-to-digital converters. At the same time, the charge amplification unit 105, instrumentation amplification unit 106, filtering unit 107, and detection unit 108 in this application can all be implemented by simple hardware circuits, and the overall cost is relatively low. Based on this, this application embodiment significantly reduces the cost of the battery module monitoring system while ensuring its functionality.

[0071] Reference Figure 8 This application also proposes an ultrasonic-based battery module monitoring method, including but not limited to steps S801 to S809:

[0072] Step S801: Sequentially control each ultrasonic receiver to turn on so that the ultrasonic receiver receives ultrasonic waves, wherein the ultrasonic waves are formed by the ultrasonic signal emitted by the ultrasonic transmitter corresponding to the ultrasonic receiver after propagating on the surface of the battery under test.

[0073] Step S802: Control each ultrasonic transmitter to transmit ultrasonic signals sequentially;

[0074] Step S803: Amplify the ultrasonic wave by charge and convert the ultrasonic wave from a charge signal to a voltage signal;

[0075] Step S804: The ultrasonic wave, after being converted into a voltage signal, is amplified for instrument use to obtain an instrument ultrasonic signal;

[0076] Step S805: Bandpass filter is applied to the instrument's ultrasonic signal to obtain a filtered ultrasonic signal;

[0077] Step S806: Envelope detection is performed on the filtered ultrasonic signal to obtain the peak envelope of the ultrasonic wave;

[0078] Step S807: The peak envelope of the ultrasound wave is acquired by AD acquisition to obtain a digital ultrasound signal;

[0079] Step S808: Determine the ultrasonic characteristic parameters based on the digital ultrasonic signal;

[0080] Step S809: Determine the health status of each battery under test based on the ultrasonic characteristic parameters.

[0081] Understandably, the main control unit sequentially activates each ultrasonic receiver, enabling it to receive the ultrasonic waves generated by the corresponding ultrasonic transmitter propagating along the surface of the battery under test. Specifically, a multiplexer is installed between the ultrasonic receiver and the signal conditioning module. This multiplexer has multiple input terminals, and each ultrasonic receiver is connected to one of these inputs. The main control unit selects the active channel by outputting a control signal to the multiplexer, allowing the ultrasonic receiver corresponding to the active channel to transmit the received ultrasonic waves to the signal conditioning module. Specifically, the main control unit outputs a periodic control signal to the multiplexer, sequentially activating each channel within each cycle. For example, with 16 ultrasonic receivers, the multiplexer has at least sixteen channels. The main control unit outputs a control signal to the multiplexer, causing channels 1 through 16 to be activated sequentially. It is understandable that by adjusting the duty cycle of the control signal, the duration of conduction of each channel can also be controlled, and the duration of conduction of each channel should match the duration of each ultrasonic signal emitted by the corresponding ultrasonic transmitter.

[0082] In some embodiments, the main control unit can output excitation signals to the ultrasonic transmitter. Specifically, the main control unit can be equipped with multiple excitation output interfaces, each connected to an ultrasonic transmitter in a one-to-one correspondence. The main control unit sequentially outputs excitation signals to the corresponding ultrasonic transmitter through each excitation output interface. Alternatively, referring to the ultrasonic-based battery module monitoring system proposed in the above embodiments, an excitation unit consisting of a switching transistor and a resistor is connected between the main control unit and each ultrasonic transmitter. The main control unit sequentially outputs control signals to the base of each switching transistor through multiple excitation output interfaces, causing the corresponding switching transistor to switch between on and off, forming a square wave excitation, thereby stimulating the ultrasonic transmitter connected to the emitter of the switching transistor to emit ultrasonic signals. It should be noted that at any given time, the main control unit will only output excitation signals to the ultrasonic transmitter corresponding to the ultrasonic receiver that is turned on, thus avoiding multiple ultrasonic transmitters working simultaneously, which could cause the ultrasonic receiver to receive ultrasonic signals emitted from other ultrasonic transmitters and create interference.

[0083] In some embodiments, the signal conditioning module receives ultrasonic waves transmitted by the activated ultrasonic receiver. It is understood that the ultrasonic receiver can be a piezoelectric ceramic wafer, which outputs an extremely weak charge signal. Therefore, it is necessary to first amplify the ultrasonic wave and convert it from a charge signal into a voltage signal. After passing through the charge amplification unit, the ultrasonic wave is converted into a voltage signal with an amplitude of tens of millivolts, which can facilitate subsequent processing of the ultrasonic wave.

[0084] Understandably, after the initial amplification by the charge amplifier, the ultrasonic wave is amplified and converted into a voltage signal with an amplitude of tens of millivolts. However, the signal amplitude is still relatively low, requiring further amplification before envelope detection to accurately reflect the changes in the ultrasonic characteristic parameters. Therefore, after charge amplification and conversion into a voltage signal, a secondary amplification by an instrumentation amplifier circuit is necessary to obtain a higher-amplitude instrumentation ultrasonic signal. It should be noted that the instrumentation ultrasonic signal refers to the ultrasonic wave after instrumentation amplification.

[0085] After instrumental amplification of the ultrasonic signal, a bandpass filter can be used to remove high-frequency and low-frequency noise, retaining the effective signal in specific frequency bands and preventing noise from affecting the battery module monitoring results. It should be noted that the filtered ultrasonic signal refers to the ultrasonic signal after bandpass filtering.

[0086] After performing charge amplification, instrumentation amplification, and bandpass filtering on the ultrasonic wave to obtain a filtered ultrasonic signal, envelope detection is performed on the filtered ultrasonic signal to extract the peak envelope of the filtered ultrasonic signal, i.e., the envelope ultrasonic signal. The envelope ultrasonic signal reflects the amplitude change of the received ultrasonic wave. The AD acquisition device acquires the signal from this envelope ultrasonic signal and converts the acquired signal into a digital signal. Since this embodiment samples the peak envelope of the ultrasonic wave instead of the instantaneous value of the ultrasonic wave, the conversion speed requirement of the AD acquisition device is low. Therefore, there is no need to use high-performance devices such as FPGAs as AD acquisition devices, which significantly reduces the cost of the battery module monitoring system.

[0087] After acquiring digital ultrasound signals from ultrasound, corresponding ultrasound characteristic parameters can be calculated based on these signals. Specifically, ultrasound characteristic parameters can include the time of flight of the ultrasound wave, the energy integral of the ultrasound wave, and the waveform index of the ultrasound wave. The time of flight, energy integral, and waveform index can be calculated using the following formulas:

[0088]

[0089]

[0090]

[0091] Where TOF is the time of flight, E is the energy integral, W is the waveform exponent, N represents the number of digital ultrasound signals acquired, and S... t The time-domain signal representing a digital ultrasound signal, i.e., time-domain data, S i t represents the amplitude of the i-th digital ultrasound signal acquired. a and t bThese are the start time of monitoring the battery under test and the last time monitoring the battery under test, respectively. The root mean square (RMS) characterizes the amplitude of the acquired digital ultrasound signal. The arithmetic mean of the amplitude of the acquired digital ultrasound signal is represented by the arithmetic mean of the amplitude. The quotient of the two values ​​can reflect the dispersion of the acquired digital ultrasound signal. The larger the value, the higher the dispersion of the acquired digital ultrasound signal.

[0092] After obtaining the corresponding ultrasonic characteristic parameters based on the digital ultrasonic signal, the health status of the battery under test can be determined according to the changes in the ultrasonic characteristic parameters. Specifically, in this embodiment, the health status of the battery under test refers to the degree of leakage and gas production. It is understood that when the battery under test leaks or produces gas, gas-liquid, gas-solid, and liquid-solid interface changes occur inside the battery. Since ultrasonic waves propagate at different speeds in different media, the flight time of the ultrasonic waves will also change significantly when leakage or gas production occurs inside the battery under test. Furthermore, referring to… Figure 9 When gas is generated inside the battery under test, bubbles will form. The ultrasonic waves will attenuate significantly as they propagate along the battery, and the energy integral coefficient of the ultrasonic waves will also decrease significantly. (Refer to...) Figure 10 When the battery under test leaks, the amplitude of the ultrasonic wave increases significantly after passing through the battery. Therefore, in this embodiment, the energy integration of the ultrasonic wave can be used to determine whether the battery under test is leaking or producing gas, thus determining the battery's health status. Furthermore, referring to the above-mentioned waveform index calculation formula, where... The root mean square (RMS) characterizes the amplitude of the acquired digital ultrasound signal. Characterizes the arithmetic mean of the amplitudes of the collected ultrasonic digital signals. The quotient of the two can reflect the degree of dispersion of the collected ultrasonic digital signals. The larger this value is, the higher the degree of dispersion of the collected digital ultrasonic signals. It can be understood that when gas production or liquid leakage occurs inside the battery under test, the amplitude of the ultrasonic wave will change significantly, which will cause a significant increase in the degree of dispersion of the amplitudes of the collected ultrasonic waves. Based on this, in this embodiment, the waveform index can be used to determine whether the battery under test has liquid leakage or gas production. Specifically, in this embodiment, each ultrasonic characteristic parameter can be compared with the corresponding reference interval respectively. When the value of the ultrasonic characteristic parameter is within the corresponding reference interval, it indicates that the battery state is normal and not damaged. Correspondingly, when the value of a certain ultrasonic characteristic parameter is not within the corresponding reference interval, it indicates that the battery under test is abnormal and the battery is damaged. In addition, when calculating the ultrasonic characteristic parameter, the ultrasonic characteristic parameter can also be added to the ultrasonic characteristic parameters corresponding to the same battery under test in several adjacent sampling periods and then averaged to perform an average filtering process on the ultrasonic characteristic parameter. In this way, the influence of periodic noise on the ultrasonic characteristic parameter can be better filtered out, and at the same time, the abnormal signals in the ultrasonic characteristic parameter can be retained, improving the accuracy of the battery monitoring system.

[0093] In the embodiment of the present application, an ultrasonic signal is sent to the battery under test through the ultrasonic transmitting end, and the ultrasonic wave formed after the ultrasonic signal propagates along the battery under test is received through the ultrasonic receiving end. After processing such as charge amplification, instrumentation amplification, band-pass filtering, and envelope detection of the ultrasonic wave, AD signal acquisition is performed on the envelope of the ultrasonic wave to obtain a digital ultrasonic signal. Based on the digital ultrasonic signal, the corresponding ultrasonic characteristic parameter is calculated, and then according to the change value of the ultrasonic characteristic parameter, it can be determined whether the battery under test has liquid leakage, gas production, etc., so as to determine the health state of the battery under test. In this embodiment, since it is the envelope of the ultrasonic signal that is collected, rather than the instantaneous value of the ultrasonic signal, the requirement for the conversion speed of the AD acquisition device is greatly reduced. Therefore, an analog-to-digital converter with a lower cost can be used as the AD acquisition device, reducing the cost of the battery module monitoring system while ensuring the function of the battery module monitoring system.

[0094] Refer to Figure 11 , step S801 includes but is not limited to steps S1101 to S1104.

[0095] Step S1101, control the i-th ultrasonic receiving end to be turned on, where i is a positive integer, 0 < i < N, and N is the number of ultrasonic signal transceiver units;

[0096] Step S1102, when the number of ultrasonic waves received by the i-th ultrasonic receiving end within the sampling period is not less than the first preset threshold, control the i-th ultrasonic receiving end to be turned off;

[0097] Step S1103: If i+1≤N, control the (i+1)th ultrasound receiver to turn on;

[0098] Step S1104: When i+1>N, control the first ultrasound receiver to turn on.

[0099] It is understood that a multiplexer is provided between the ultrasonic receiver and the signal conditioning module. The main control unit controls the channel of the multiplexer to enable the ultrasonic receiver corresponding to the channel to transmit ultrasonic waves to the signal conditioning module. In this embodiment, the main control unit controls the i-th channel of the multiplexer to be turned on, so that the i-th ultrasonic receiver is turned on. The i-th ultrasonic receiver will receive multiple sets of ultrasonic waves within the sampling period. It is understood that the sampling period here refers to the duration of each time the i-th ultrasonic receiver is turned on. For example, the i-th ultrasonic receiver can receive 12 sets of ultrasonic waves each time it is turned on. It is understood that for the peak envelope of each set of ultrasonic waves, the number of sampling points and the sampling frequency of the analog-to-digital converter are the same. For example, the analog-to-digital converter can collect 75 points for the peak envelope of each ultrasonic wave. Correspondingly, within the sampling period, the main control unit will output multiple control signals to the i-th ultrasonic transmitter so that the i-th ultrasonic transmitter will emit multiple ultrasonic signals within the sampling period. For example, the main control unit will output 12 excitation signals to the i-th ultrasonic transmitter within the sampling period so that the i-th ultrasonic transmitter will emit 12 ultrasonic signals within the sampling period.

[0100] In some embodiments, when the number of ultrasonic waves received by the i-th ultrasonic receiver within the sampling period is not less than a first preset threshold, the main control unit shuts off the connection corresponding to the i-th ultrasonic receiver and switches to the next ultrasonic receiver. Specifically, when i+1≤N, the channel in the multiplexer corresponding to the (i+1)-th ultrasonic receiver is turned on, and the main control unit outputs an excitation signal to the (i+1)-th ultrasonic transmitter to start detecting the (i+1)-th battery module under test. When i+1>N, it indicates that one cycle of detecting the battery under test has been completed, and the detection should start again from the first battery under test. At this time, the main control unit should control the channel between the first ultrasonic receiver and the signal conditioning module to be turned on, and the main control unit should also output an excitation signal to the first ultrasonic transmitter.

[0101] In some embodiments, refer to Figure 12 Step S807 includes, but is not limited to, steps S1201 to S1202.

[0102] Step S1201: Data acquisition is performed on the peak envelopes of multiple ultrasonic waves received by the ultrasonic receiver within the same sampling period;

[0103] Step S1202: Calculate the average amplitude of multiple ultrasonic waves acquired by the same ultrasonic receiver within the same sampling period to obtain the digital ultrasonic signal of the ultrasonic receiver within the corresponding sampling period.

[0104] It is understandable that within a sampling period, the main control unit will send multiple excitation signals to the same ultrasonic transmitter before controlling the next ultrasonic transmitter to send an excitation signal. The ultrasonic transmitter will emit multiple ultrasonic signals within this sampling period. Correspondingly, the ultrasonic receiver will also receive multiple ultrasonic waves within the same sampling period. The signal conditioning module will perform charge amplification, instrument amplification, bandpass filtering, and envelope detection on each ultrasonic wave, while the AD acquisition device will also acquire the peak envelope of each ultrasonic wave. Specifically, in one embodiment, the main control unit will output 12 excitation signals to the same ultrasonic transmitter within one sampling period. In response to the excitation signals, the ultrasonic transmitter will emit 12 ultrasonic signals within one sampling period.

[0105] In some embodiments, the average amplitude of multiple ultrasound waves acquired by the same ultrasound receiver within the same sampling period is calculated as the digital ultrasound signal generated by the ultrasound receiver within that sampling period. Specifically, the analog-to-digital conversion module acquires data of the peak envelope of each ultrasound wave received by the ultrasound receiver within that sampling period. The sampling frequency and the number of sampling points are the same each time. Based on this, the analog-to-digital conversion module samples multiple sets of ultrasound wave amplitudes. Each set of ultrasound wave amplitudes can include the values ​​of multiple sampling points. For example, the ultrasound receiver can receive 12 ultrasound waves in each sampling period, and the analog-to-digital conversion module acquires 75 data points for the envelope of each ultrasound wave. This generates a total of 12 sets of ultrasound envelope amplitude data, each with 75 sampling points. The average value of each sampling point in the 12 sets of ultrasound envelope amplitudes is calculated, thus obtaining the digital ultrasound signal of the ultrasound receiver within that sampling period. It is understandable that, in this embodiment, when the main control module calculates the average value of multiple ultrasonic waves received by the same ultrasonic receiver within the same sampling period, it can directly use the binary value output by the analog-to-digital converter module for calculation, without first converting it into a specific voltage value. After calculating the average value of multiple ultrasonic waves collected by the ultrasonic receiver within the same sampling period based on the binary value output by the analog-to-digital converter module, the binary value is then converted into a specific voltage value for output. In this way, the amount of calculation in the averaging process can be reduced, the calculation efficiency can be improved, and the requirements on the clock frequency of the main control module can be reduced.

[0106] In this embodiment, by calculating the average value of the peak envelope amplitude of multiple ultrasonic waves received by the ultrasonic receiver within the sampling period as the corresponding digital ultrasonic signal, the influence of periodic noise on the acquired digital ultrasonic signal can be effectively eliminated, thereby improving the accuracy of the battery module monitoring system.

[0107] In some embodiments, refer to Figure 13 Step S809 includes, but is not limited to, steps S1301 to S1302.

[0108] Step S1301: Compare the flight time, energy integral, and waveform index of two consecutive digital ultrasonic signals corresponding to the same battery under test with the corresponding reference intervals.

[0109] Step S1302: If at least one of the changes in flight time, energy integral, and waveform index is not within the corresponding reference range, the health status of the battery under test is determined to be damaged.

[0110] Specifically, in this embodiment, ultrasonic signals are cyclically transmitted to each battery under test and the corresponding ultrasonic waves are received to generate digital ultrasonic signals. The main control unit records the ultrasonic characteristic parameters of each digital ultrasonic signal of each battery under test and compares the change values ​​between the ultrasonic characteristic parameters of two adjacent digital ultrasonic signals of the same battery under test with a reference interval. It can be understood that the reference interval can be given in advance based on empirical values. The ultrasonic characteristic parameters may include the flight time of the ultrasonic wave, the energy integral of the ultrasonic wave, and the waveform index of the ultrasonic wave. Specifically, the calculation methods of the flight time of the ultrasonic wave, the energy integral of the ultrasonic wave, and the waveform index of the ultrasonic wave are the same as those in the above embodiment and will not be repeated here. Understandably, when the battery under test is undamaged, the ultrasonic characteristic parameters of two adjacent digital ultrasonic signals should be relatively close. However, if the change value between the ultrasonic characteristic parameters of two adjacent digital ultrasonic signals is not within the given reference range, it indicates that the change value of these two ultrasonic characteristic parameters is too large. At this time, it can be determined that the battery under test has leaked or produced gas. The gas-liquid, gas-solid, and liquid-solid interface changes inside the battery cause a significant change in the flight time of the ultrasonic waves, or the presence of internal gas causes a significant attenuation of the ultrasonic signal during transmission, or the leakage causes the ultrasonic waves to be enhanced during propagation.

[0111] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual order of execution may change depending on the specific circumstances.

[0112] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0113] The terms “comprising” and “having”, and any variations thereof, in the specification and accompanying drawings of this application are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are expressly listed, but may include other steps or units that are not expressly listed or that are inherent to such process, method, product, or apparatus.

[0114] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0115] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0116] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. An ultrasonic-based battery module monitoring system, the system being used to monitor the health status of a battery module, the battery module comprising at least one battery to be tested, characterized in that, The system includes: An ultrasonic module includes at least one ultrasonic signal transceiver unit, which is correspondingly configured with the battery under test. The ultrasonic signal transceiver unit includes an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic receiver is used to receive ultrasonic waves, which are formed by the ultrasonic signal emitted by the corresponding ultrasonic transmitter propagating on the surface of the battery under test. A signal conditioning module is connected to each of the ultrasound receivers. The signal conditioning module includes a charge amplification unit, an instrument amplification unit, a filtering unit, and a detection unit connected in sequence. The charge amplification unit is used to amplify the ultrasound received by the ultrasound receiver and convert the ultrasound from a charge signal to a voltage signal. The instrument amplification unit is used to amplify the ultrasound after it has been converted to a voltage signal. The filtering unit is used to filter out the harmonic components in the ultrasound. The detection unit is used to perform envelope detection on the ultrasound after the harmonics have been filtered out to obtain the peak envelope of the ultrasound. An analog-to-digital conversion module is used to perform AD acquisition on the peak envelope of the ultrasonic wave to obtain a digital ultrasonic signal; The main control unit is connected to the analog-to-digital conversion module and is used to receive the digital ultrasonic signal output by the analog-to-digital conversion module. The main control unit is also used to determine ultrasonic characteristic parameters based on the digital ultrasonic signal and to determine the health status of the battery under test based on the change value of the ultrasonic characteristic parameters. The detection unit includes an envelope detector chip, a first rectifier diode, a second rectifier diode, a fifth capacitor, a sixth capacitor, a variable resistor unit, and a fifth resistor. The envelope detector chip is composed of a third operational amplifier unit and a fourth operational amplifier unit. The first terminal of the first rectifier diode is connected to the output terminal of the third operational amplifier unit, and the second terminal of the third operational amplifier unit is connected to the inverting input terminal of the third operational amplifier unit. The second terminal of the first rectifier diode is connected to the first fixed terminal of the variable resistor unit. The first terminal of the first rectifier diode is connected to the first terminal of the second rectifier diode. The first rectifier diode is also connected in parallel with the sixth capacitor. The sliding terminal of the variable resistor unit is connected to the second terminal of the second rectifier diode. The second rectifier diode is connected to the first terminal of the fifth capacitor, and the second terminal of the fifth capacitor is grounded. The fifth capacitor is also connected in parallel with the fifth resistor to form an RC circuit. The second terminal of the second rectifier diode is also connected to the non-inverting input terminal of the fourth operational amplifier unit. The inverting input terminal of the fourth operational amplifier unit is connected to the output terminal of the fourth operational amplifier unit. The output terminal of the fourth operational amplifier unit is connected to the analog-to-digital conversion module and the sliding terminal of the variable resistor unit, respectively.

2. The ultrasonic-based battery module monitoring system according to claim 1, characterized in that, The ultrasound-based battery module monitoring system further includes: multiple excitation units, each excitation unit being configured in a one-to-one correspondence with an ultrasonic transmitter. Each excitation unit is used to output an excitation signal to the corresponding ultrasonic transmitter, so that the ultrasonic transmitter receiving the excitation signal transmits the ultrasonic signal. Each excitation unit is connected to the main control unit, and the main control unit is used to control the excitation units to be turned on sequentially so that the multiple ultrasonic transmitters transmit the ultrasonic signal sequentially.

3. The ultrasonic-based battery module monitoring system according to claim 1, characterized in that, The ultrasound-based battery module monitoring system further includes a multiplexer connected between the signal conditioning module and each ultrasound receiver. The multiplexer is used to control the on / off state of each ultrasound receiver. The multiplexer is connected to the main control unit, which is also used to control each channel of the multiplexer to be sequentially turned on so that the multiple ultrasound receivers sequentially transmit the received ultrasound waves to the signal conditioning module.

4. The ultrasonic-based battery module monitoring system according to claim 1, characterized in that, The charge amplification unit includes a first operational amplifier unit. The first input terminal of the first operational amplifier unit is connected to the ultrasonic receiver. The second input terminal of the first operational amplifier unit is grounded. The output terminal of the first operational amplifier unit is connected to the input terminal of the instrument amplification unit. A first capacitor is connected between the input terminal of the first operational amplifier unit and the ultrasonic receiver. The charge amplification unit also includes a first resistor and a second capacitor. One end of the first resistor is connected to the output terminal of the first operational amplifier unit, and the other end of the first resistor is connected to the first input terminal of the first operational amplifier unit. The second capacitor and the first resistor are connected in parallel between the output terminal and the first input terminal of the first operational amplifier unit.

5. The ultrasonic-based battery module monitoring system according to claim 1, characterized in that, The instrumentation amplification unit includes a second operational amplifier unit. The first input terminal of the second operational amplifier unit is connected to the output terminal of the charge amplification unit. The second input terminal of the second operational amplifier unit is grounded. A gain adjustment resistor is connected between the two gain adjustment pins of the second operational amplifier unit. The first and second output terminals of the second operational amplifier unit are connected to the input terminal of the filter unit.

6. The ultrasonic-based battery module monitoring system according to claim 1, characterized in that, The filtering unit includes a non-inverting amplifier. The input terminal of the non-inverting amplifier is connected to the output terminal of the instrumentation amplifier unit. A third capacitor and a second resistor are connected sequentially between the output terminal of the instrumentation amplifier unit and the input terminal of the non-inverting amplifier. A fourth capacitor and a third resistor are bypassed between the second resistor and the input terminal of the non-inverting amplifier and then grounded. The third capacitor and the third resistor form a first-order passive high-pass filter circuit, and the second resistor and the fourth capacitor form a first-order passive low-pass filter circuit. The output terminal of the non-inverting amplifier is connected to the input terminal of the detector unit. The output terminal of the non-inverting amplifier is also connected to the feedback input terminal of the non-inverting amplifier. A fourth resistor is connected between the output terminal of the non-inverting amplifier and the feedback input terminal.

7. A battery module monitoring method based on ultrasound, applied to the ultrasonic-based battery module monitoring system as described in any one of claims 1 to 6, characterized in that, The method includes: Each of the ultrasonic receivers is turned on sequentially so that it receives ultrasonic waves, wherein the ultrasonic waves are formed by the ultrasonic signal emitted by the ultrasonic transmitter corresponding to the ultrasonic receiver and then propagating on the surface of the battery under test. Each of the ultrasonic transmitters is controlled to sequentially transmit the ultrasonic signal; The ultrasonic wave is amplified by charge and converted from a charge signal to a voltage signal; The ultrasonic wave, after being converted into a voltage signal, is amplified for instrumental use to obtain an instrumental ultrasonic signal. The instrument's ultrasonic signal is bandpass filtered to obtain a filtered ultrasonic signal; Envelope detection is performed on the filtered ultrasonic signal to obtain the peak envelope of the ultrasonic wave; The peak envelope of the ultrasonic wave is acquired by AD acquisition to obtain the digital ultrasonic signal; Determine the ultrasonic characteristic parameters based on the digital ultrasonic signal; The health status of each battery under test is determined based on the ultrasonic characteristic parameters.

8. The method according to claim 7, characterized in that, The step of performing AD acquisition on the peak envelope of the ultrasonic wave to obtain the digital ultrasonic signal includes: Data is collected on the peak envelopes of multiple ultrasonic waves received by the ultrasonic receiver within the same sampling period. The average value of the peak envelopes of multiple ultrasound waves acquired by the same ultrasound receiver within the same sampling period is calculated to obtain the digital ultrasound signal of the ultrasound receiver within the corresponding sampling period.

9. The method according to claim 7, wherein the ultrasonic characteristic parameters include time of flight, energy integral, and waveform index, characterized in that, Determining the health status of each battery under test based on the ultrasonic characteristic parameters includes: The changes in flight time, energy integral, and waveform exponent of two consecutive digital ultrasonic signals corresponding to the same battery under test are compared with the corresponding reference intervals. If at least one of the changes in flight time, energy integral, and waveform index is not within the corresponding reference interval, the health status of the battery under test is determined to be damaged.

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