DESC:SYSTEM TO QUANTIFY WELD QUALITY FOR A BATTERY PACK
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202321090114 filed on 30/12/2023, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure relates to a quality check method for a battery pack. Particularly, the present disclosure relates to a system and method for determining weld quality for a battery pack.
BACKGROUND
Recently, there has been a rapid development in electric vehicles because of their due to their ability to combat pollution and serve as a cleaner alternative for transportation. Generally, electric vehicles include a power pack, and/or combination of electric cells for storing electricity required for the propulsion of the vehicles. The electrical power stored in the power pack of the electric vehicle is supplied to the traction motor and various other electrical components for the operation of the electric vehicle.
In a power pack, a plurality of battery cells are connected in parallel or series combination via busbar(s). Generally, for connecting the plurality of battery cells busbar is welded on cell tabs via laser or spot welding, and weld strength and/or weld quality plays an important role in the overall performance and safety of the powerpack. Conventional methods available for weld quality determination involve detecting weld quality by analysing weld mark. The methods for detecting weld quality include Automated Optical Inspection (AOI), eddy current testing, and acoustic emission testing. The (AOI) method involves capturing high-resolution images of the weld area and analysing the images with computer vision and machine learning techniques to detect defects. Further, the eddy current testing method includes induction of eddy currents in the weld material, and the response is analysed to detect surface or near-surface flaws in the weld area. The acoustic emission testing monitors the high-frequency sound emitted by the weld area under stress to detect cracks or other failures.
However, there are certain underlining problems associated with the above-mentioned existing mechanism of detecting weld quality. For instance, the AOI method is light sensitive and therefore, it is challenging to capture all defect types in complex weld geometries. Further, the eddy current testing method is affected by material and surface composition and, therefore, does not provide accurate results for determining the weld quality. Furthermore, acoustic emission testing is sensitive to noise, and therefore the external vibrations or noise in the environment may interfere with the detection of the weld quality.
Therefore, there exists a need for a mechanism for determining weld quality that is accurate and overcomes one or more problems as mentioned above.
SUMMARY
An object of the present disclosure is to provide a system for determining weld quality between a busbar and at least one battery cell of a battery pack.
Another object of the present disclosure is to provide a method of determining weld quality between a busbar and at least one battery cell of a battery pack.
Yet another object of the present disclosure is to provide a system and method for determining weld quality, with improved accuracy.
In accordance with a first aspect of the present disclosure, there is provided a system for determining weld quality between a busbar and at least one battery cell of a battery pack, the system comprises:
- at least one battery cell array comprising a plurality of battery cells, connected via the busbar and;
- a fixture configured to hold the at least one battery cell array for determining weld quality, the fixture comprises:
- at least one voltage source;
- at least one sensing arrangement;
- a signal processing unit;
- at least one signal conditioning unit; and
- a data processing arrangement,
wherein the data processing arrangement, when in operation, is configured to compute impedance variation for connections between the busbar and the plurality of battery cells.
The system and method for determining weld quality between a busbar and at least one battery cell of a battery pack, as described in the present disclosure, is advantageous in accurately determining the weld quality based on the impedance variation computation. Advantageously, the impedance variation between the busbar and battery cells provides precise identification of the welding defects (inconsistency) or degradation in the connection quality over time. Further, the computation of impedance phase shift provides real-time information of the battery electrochemical state and thereby, informed operations are performed to protect the cells from damage.
In accordance with another aspect of the present disclosure, there is provided a method of determining weld quality between a busbar and at least one battery cell of a battery pack, the method comprises:
- supplying a reference voltage signal across a plurality of battery cells via at least one voltage source;
- generating a band-pass voltage digital signal and a band-pass current digital signal, via at least one analog to digital converter;
- modulating an amplitude of the band-pass voltage digital signal and band-pass current digital signal, via at least one signal conditioning unit;
- computing a magnitude of voltage and current corresponding to the modulated band-pass voltage digital signal and band-pass current digital signal, via a data processing unit; and
- computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal, via the data processing unit.

Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figures 1 and 2 illustrate block diagrams of a system for determining weld quality between a busbar and at least one battery cell of a battery pack, in accordance with different embodiments of the present disclosure.
Figure 3 illustrates a flow chart of a method of determining weld quality between a busbar and at least one battery cell of a battery pack, in accordance with another embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
As used herein, the term “busbar” refers to a conductive material for distributing electrical power between the battery cells and other electrical components of the vehicle power system. The busbar acts as a bridge to connect the battery cells in series or parallel arrangements, enabling the efficient flow of electricity from the battery to the motor. The busbar ensures low resistance, reduces energy loss, and prevents overheating in the electrical circuits of the vehicle. Further, the busbar controls high currents without causing excessive voltage to drop, ensuring the stability and reliability of the vehicle power system. Moreover, the busbar has features such as (but not limited to) insulation, heat sinks, and thermal management solutions to mitigate risks associated with electrical faults, short circuits, or thermal runaway. By ensuring a safe and effective power distribution system, the busbar acts as an integral components that contribute to the overall performance, durability, and safety of the electric vehicle energy storage and delivery system.
As used herein, the terms “battery cell”, and “cell” are used interchangeably and refer to an electrochemical unit that stores and releases electrical energy to power the electric vehicle motor and other electrical components. Each battery cell contains a positive electrode (cathode), a negative electrode (anode), and an electrolyte that allows the flow of ions between the electrodes during charging and discharging. The performance and lifespan of the electric vehicle battery are determined by the type and quality of the individual battery cells, which are combined into larger battery packs to meet the required voltage and capacity for the vehicle operational needs. Additionally, other factors such as, but not limited to, thermal management, charge/discharge cycles, and safety features are integral factors in battery cell design. The health and performance of each cell are monitored by Battery Management Systems (BMS) ensuring balanced operation and preventing overcharging or deep discharge.
As used herein, the term “battery pack” refers to a collection of individual battery cells that are arranged and connected together to provide the required voltage, capacity, and energy output to power the bike's motor and other electrical components. A battery pack consists of multiple cells linked in series and/or parallel, ensuring vehicle power to operate over the desired range. The battery pack is designed to handle high currents during acceleration, regenerative braking, and high-speed riding while maintaining an optimal balance between performance, weight, and safety. Further, the battery pack also incorporates components such as a battery management system, thermal management system, and protective casing. The battery management system monitors the health of each cell within the pack, ensuring that voltage and temperature levels stay within safe limits, preventing overcharging, deep discharge, and thermal runaway. The thermal management systems, such as, but not limited to, cooling plates or vents, dissipate heat generated during charging and discharging, ensuring that the cells remain within optimal temperature ranges for maximum performance and longevity. Additionally, the protective casing safeguards the cells from physical damage and environmental factors like moisture or dust, ensuring the pack remains durable and safe for long-term use in demanding conditions.
As used herein, the term “fixture” refers to a mechanical structure or device used to securely hold the position of various components of the battery pack, such as individual cells, busbars, battery management system, and thermal management components. The fixture ensures that all parts are properly aligned, and thereby prevents the movement or vibration of the components. Consequently, the fixture maintains the integrity and performance of the battery pack. Further, the fixtures are made from materials such as, but not limited to, metal, plastic, or composites, based on their strength, lightweight properties, and resistance to environmental factors. Moreover, the fixture includes safety features such as insulation or separation layers to protect against short circuits, impact damage, or electrical faults.
As used herein, the terms “voltage source”, and “voltage supply” are used interchangeably and refer to a power supply that provides a stable and controlled voltage to the battery, ensuring it is charged safely and efficiently. The primary function of a voltage source to apply a voltage that is higher than the battery's current charge voltage, allowing current to flow into the battery cells. In the initial stage, a constant current is applied until the battery reaches its rated voltage, at which point the voltage source switches to a constant voltage mode to maintain the battery at its peak voltage. The constant current and constant voltage ensure that the battery is charged efficiently while preventing overheating, overvoltage, or other conditions that could compromise the battery’s performance or safety. The voltage source further includes features such as current limiting, thermal monitoring, and feedback mechanisms to ensure that the charging process stays within safe operating parameters for the battery cells.
As used herein, the term “sensing arrangement” refers to an arrangement of sensors and monitoring devices integrated within the battery pack and electrical components to continuously monitor parameters such as, but not limited to voltage, temperature, current, and state of charge of the battery cells. The sensors provide real-time data to the battery management system, which utilizes this information to optimize battery performance, protect the cells from unsafe conditions, and ensure the overall safety and reliability of the electric vehicle. The sensors may include such as, but not limited to, voltage sensors, current sensors, and temperature sensors. The voltage sensors monitor the voltage levels of individual cells or groups of cells within the pack, while temperature sensors ensure that the cells remain within safe operating temperature ranges to avoid overheating or thermal runaway. The current sensors monitor the charging and discharging rates, ensuring that the BMS manages energy flow and prevents overcurrent conditions.
As used herein, the term “signal processing unit” refers to a computation unit that processes and analyses the data collected from various sensors within the battery pack. The signal processing unit converts raw signals from sensors, such as voltage, current, and temperature readings, into digital data that are analysed and operated based on operational requirements. The signal processing unit employs Analog-to-Digital Converters (ADCs) to digitize the sensor outputs, allowing for more accurate and precise monitoring of battery conditions. The processing of the above-mentioned digital data enables real-time analysis of key parameters such as, but not limited to, state of charge, state of health, and the thermal status of the cells. The processed signals are received by a central control unit and safety operations are applied. In addition to basic data conversion, the signal processing unit filters and conditions the sensor signals to eliminate noise or errors caused by electrical interference or environmental factors and thereby ensures the data is accurate and reliable for decision-making.
As used herein, the term “signal conditioning unit” refers to a subsystem that processes and modifies the raw electrical signals generated by sensors. The signal conditioning unit ensures that the data analysis is accurate, clean, and within a usable range. Further, the signal conditioning unit performs the scaling of the input signals to match the required range for processing of the signals. For instance, a temperature sensor output signal is amplified to match the range of the subsequent units. Additionally, the conditioning of the signals ensures that the BMS is able to achieve precise decisions regarding the battery performance, such as adjusting charging rates, balancing cells, or triggering safety measures for thermal protection or overvoltage cutoff.
As used herein, the term “data processing arrangement” refers to a unit that interprets the conditioned data and performs algorithms to assess the overall health, efficiency, and status of the battery pack. The data processing unit involves microcontrollers or Digital Signal Processors (DSPs) to calculate the critical battery pack parameters such as state of health, charge cycles, and energy consumption, allowing the system to monitor battery performance in real-time and predict future requirements or potential issues. Further, the data processing arrangement executes decision-making to trigger actions such as balancing the individual cells, adjusting the charging rate, activating cooling mechanisms, or initiating protective measures like switching off the communication in case of an overvoltage, under-voltage, or over-temperature condition. Furthermore, the data processing arrangement facilitates communication with external systems, such as charging stations or user interfaces, to provide feedback on battery status, charge levels, and remaining range, enhancing the overall user experience and safety of the electric vehicle.
As used herein, the term “impedance variation” refers to the change in the resistance of the cell during the flow of electrical current under different operating conditions. The variation is influenced by the state of charge, temperature, and the age of the battery. At a higher state of charge, impedance is lower due to the fully charged state of the cell, and at a lower state of charge results in higher impedance due to a decrease in ion mobility within the battery. Additionally, at lower temperatures impedance increases due to reduced electrochemical reaction rates, and higher temperature impedance decreases. The variation in impedance affects the performance and efficiency of the electric vehicle. A higher impedance value indicates a higher internal resistance, leading to losses in power delivery, reduced range, and potential heat buildup. Therefore, monitoring impedance changes facilitates battery life prediction, charging strategies optimization, and ensuring the long-term reliability of the electric vehicle power system.
As used herein, the term “band-pass filter” refers to a signal processing circuit used to allow only certain frequencies of electrical signals to pass through while attenuating frequencies outside a specific range. Particularly, the band-pass filter enables noise filtering and improves the accuracy of measurements related to the battery performance, such as voltage, current, or impedance. The band-pass filter allows the frequency range of interest that is significant to the battery operating characteristics, such as the frequency of current ripple or electromagnetic interference generated during charging and discharging cycles. Further, the filtering of high-frequency noise and low-frequency drift ensures that only significant, stable signals are used for control unit calculations and control.
As used herein, the terms “analog to digital converter” and “ADC” are used interchangeably and refer to an integrated circuit used to convert a continuous analog signal to a digital signal. The ADC compares samples of the continuous analog signal to a known reference voltage and then produces a digital representation at the output in the form of a digital binary code. Further, the continuous analog signals may include (but not limited to) temperature, voltage, current, power, pressure, acceleration, and speed.
As used herein, the term “phase shift” refers to a delay or shift between the voltage and current signal during the battery charging or discharging. The phase shift arises due to the internal resistance, inductance, and capacitive characteristics of the battery. The delay is influenced by the battery state of charge, temperature, and the rate of current flow. A large phase shift indicates that the battery is not completely utilizing the available current to generate power, leading to energy losses. Additionally, the phase shift also signifies the battery health, as an increase in phase shift over time indicates the development of internal resistance or degradation of the battery's electrochemical components.
As used herein, the term “predefined threshold impedance” refers to a value of impedance that the vehicle control unit employs as a standard to assess the health and performance of the battery cells. Impedance in a battery is the resistance the battery provides to the flow of current that varies based on the state of charge, temperature, and the age of the battery. The predefined threshold impedance is computed during the battery design and testing phase and is based on the normal operating range of impedance for a healthy battery. The threshold facilitates the vehicle control unit to identify exceedance of impedance from acceptable limits indicating degradation, internal damage, or increased resistance due to aging or overheating.
In accordance with a first aspect of the present disclosure, there is provided a system for determining weld quality between a busbar and at least one battery cell of a battery pack, the system comprises:
- at least one battery cell array comprising a plurality of battery cells, connected via the busbar; and
- a fixture configured to hold the at least one battery cell array for determining weld quality, the fixture comprises:
- at least one voltage source;
- at least one sensing arrangement;
- a signal processing unit;
- at least one signal conditioning unit; and
- a data processing arrangement,
wherein the data processing arrangement, when in operation, is configured to compute impedance variation for connections between the busbar and the plurality of battery cells.
Referring to figure 1, in accordance with an embodiment, there is described a system 100 for determining weld quality between a busbar 102 and at least one battery cell 104 of a battery pack 106. The system 100 comprises at least one battery cell array 108 comprising a plurality of battery cells 104, connected via the busbar 102 and a fixture 110 configured to hold the at least one battery cell array 108 for determining weld quality. Further, the fixture 110 comprises at least one voltage source 112, at least one sensing arrangement 114, a signal processing unit 116, at least one signal conditioning unit 118, and a data processing arrangement 120. Furthermore, the data processing arrangement 120, when in operation, is configured to compute impedance variation for connections between the busbar 102 and the plurality of battery cells 104.
The battery cell array 108 comprising multiple cells connected via the busbar 102 enables a comprehensive assessment of weld integrity across all connections. Further, the inclusion of the fixture to securely hold the battery cell array 108 to determine weld quality ensures that each weld joint is precisely monitored under consistent conditions, minimizing errors due to mechanical movement or misalignment. Moreover, the system integration of the voltage source 112, sensing arrangement 114, signal processing unit 116, and signal conditioning unit 118 facilitates real-time monitoring and fine-tuned measurement of electrical characteristics, allowing for early detection of defects such as (but not limited to) non-uniform welds, resistive connections, or inconsistencies in impedance. Furthermore, the data processing arrangement 120 computes impedance variation between the busbar 102 and battery cells indicating defects such as contact resistance, welding defects (non-uniformity), or degradation in the connection quality over time. The impedance-based measurement provides a non-destructive mechanism to assess weld quality, offering significant advantages over traditional visual or mechanical inspection methods. The ability to process and analyse this data in real-time ensures continuous feedback to the manufacturing process, enabling timely adjustments of welding parameters and improving overall weld consistency.
In an embodiment, the at least one voltage source 112 is configured to supply a reference voltage signal across the plurality of battery cells 104. Advantageously, a stable and consistent reference voltage ensures that the data processing arrangement 120 accurately monitors and compares the voltage of each cell in the pack. Subsequently, the comparison enables the data processing arrangement 120 to assess the state of charge of each cell and perform the cell balancing efficiently. Further, the reference voltage acts as a reference that allows the data processing arrangement 120 to detect any deviations from the expected voltage behaviour, such as overcharging or undercharging, and trigger protective actions to prevent damage to the cells. Consequently, the overall safety and reliability of the vehicle battery system is improved and the risk of thermal runaway, voltage imbalance, and reduced capacity due to improper charge cycles is minimized.
In an embodiment, the at least one sensing arrangement 114 is configured to sense a voltage and current signal across the at least one battery cell 104. The continuous sensing of the voltage and current enables the data processing arrangement 120 to precisely monitor power flow in and out of each cell. Consequently, state of charge, state of health, and energy efficiency are calculated accurately via the data processing arrangement 120, enabling optimized charging, discharging, and balancing algorithms. By continuously monitoring voltage and current, the data processing arrangement 120 detects abnormal behaviour such as overcurrent conditions, voltage imbalances, or excessive heat generation. Early detection of the issues allows the system to take protective actions, such as adjusting the charge/discharge rates, activating thermal management, or isolating faulty cells, thereby preventing damage to the overall pack.
Referring to figure 2, in accordance with an embodiment, there is described a system 100 for determining weld quality between a busbar 102 and at least one battery cell 104 of a battery pack 106. The system 100 comprises at least one battery cell array 108 comprising a plurality of battery cells 104, connected via the busbar 102 and a fixture 110 configured to hold the at least one battery cell array 108 for determining weld quality. Further, the fixture 110 comprises at least one voltage source 112, at least one sensing arrangement 114, a signal processing unit 116, at least one signal conditioning unit 118, and a data processing arrangement 120. Furthermore, the data processing arrangement 120, when in operation, is configured to compute impedance variation for connections between the busbar 102 and the plurality of battery cells 104. Furthermore, the signal processing unit 116 comprises at least one band-pass filter 122 and at least one analog-to-digital converter 124. The band-pass filter is designed to isolate a specific frequency range of interest and attenuate redundant high-frequency noise. The band-pass filter 122 ensures that only the relevant frequency signals, such as those related to current ripple or battery impedance variations, are passed to the subsequent stages of processing. This helps to enhance the signal-to-noise ratio (SNR), ensuring more precise voltage and current measurements, which is critical for accurate battery monitoring, diagnostics, and management. Additionally, the analog-to-digital converter 124 converts the filtered analog signals into digital form for further processing by the data processing arrangement 120. Further, the ADCs 124 ensures that the analog voltage and current signals are converted into digital data with minimal quantization errors and high resolution. The minimal quantization error allows the data processing arrangement 120 to perform an accurate state of charge, state of health, and power efficiency.
In an embodiment, the at least one band-pass filter 122 is configured to receive the voltage and current signal across the at least one battery cell 104.
In an embodiment, the at least one band-pass filter 122 is configured to pass a range of frequencies of the voltage and current signal based on a frequency of the reference voltage signal. The band-pass filter 122 allows only a specific range of frequencies to pass based on the operation of the required signal. Particularly, the band-pass filter removes high-frequency noise and low-frequency drift, such as current ripple or impedance variations. Consequently, passing the desired frequency range ensures that the voltage and current signals have the least noise distortion leading to more reliable state of charge calculations, efficient power delivery, and optimized charging and discharging cycles. Additionally, the band-pass filters 122 out irrelevant frequencies such as frequency patterns indicating fluctuations in internal resistance and/or degradation within individual cells. Consequently, the data processing arrangement 120 accurately detects the potential issues and thereby, preventing failures and ensuring that the battery operates within optimal parameters.
In an embodiment, the at least one analog to digital converter 124 is configured to receive the band-pass voltage and current signal, and generate a band-pass voltage digital signal and a band-pass current digital signal, corresponding to the received band-pass voltage and current signal. The band-pass filter 122 isolates the desired frequency range from the voltage and current signals and subsequently, converts the band-pass voltage and current signal into precise digital representations for processing by the data processing arrangement 120. Further, the ADC 124 ensures that the conversion process only converts the relevant portions of the band-pass voltage and current signal that are minimized in noise or interference. Additionally, the digital conversion of the band-pass voltage and current signals enables the data processing arrangement 120 to perform advanced computations and diagnostics with greater efficiency and precision. The digital signals are simpler to modulate, analyse, and store, allowing the data processing arrangement 120 to implement algorithms for optimal charging, discharging, balancing, and thermal management. With accurate digital data representing the band-pass voltage and current signals, the system can detect small variations or trends that might indicate underlying issues such as rising internal resistance or early cell degradation. This leads to more proactive maintenance, better energy efficiency, and improved battery lifespan.
In an embodiment, the at least one signal conditioning unit 118 is configured to modulate an amplitude of the generated band-pass voltage digital signal and band-pass current digital signal received from the at least one analog to digital converter 124. The signal conditioning involves modulating the amplitude of the digital signals to a level that is optimal for subsequent processing stages, ensuring that the signals are within the operating range of the data processing arrangement 120. The modulation of the amplitude ensures that the voltage and current digital signals are not overly weak (resulting in reduced resolution) or excessively strong (resulting in saturation or distortion). Consequently, the modulated digital signals are robust and less susceptible to noise, thereby enhancing the precision of battery monitoring and control algorithms, such as (but not limited to) state of charge estimation, battery balancing, and thermal management. Additionally, the efficient modulation of the band-pass voltage digital signal and band-pass current digital signal enables the powertrain to operate with lower energy loss and reduced computational overhead, improving the overall energy efficiency of the vehicle and contributing to a longer battery lifespan.
In an embodiment, the data processing arrangement 120 is configured to compute a magnitude of voltage and current corresponding to the band-pass voltage digital signal and band-pass current digital signal received from the at least one signal conditioning unit 118. The computation of the magnitude of voltage and current enables the data processing arrangement 120 to analyse the resistance, power, energy consumption, and internal resistance of each battery cell which are essential for accurately assessing the battery’s state of charge, state of health, and overall efficiency. The magnitude calculations enable the data processing arrangement 120 to analyse the real power being drawn or delivered by the battery. Further, the continuous monitoring of the magnitude of these signals, allows the data processing arrangement 120 to detect potential issues such as increased internal resistance, power losses, or inefficiencies that lead to thermal stress or accelerated wear on the cells.
In an embodiment, the data processing arrangement 120 is configured to compute an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal based on the computed magnitude of the voltage and current. The computation of the impedance provides the internal resistance of each battery cell 104 which further reflects the efficiency of the battery in delivering or absorbing power. Further, the impedance enables the data processing unit 120 to provide a precise measure of the battery health, indicating the loss of energy due to internal resistance. Additionally, the phase shift calculation between the voltage and current signals provides an additional layer of diagnostic capability, allowing the data processing unit 120 to monitor the dynamic behaviour of the battery during charging and discharging cycles. The phase shift is a delay between the voltage and current waveforms that indicates rising internal resistance or electrochemical degradation in the battery cells. Therefore, computing the phase shift along with impedance, the data processing unit 120 provides real-time information of the battery electrochemical state and thereby, performs informed operations to protect the cells from damage.
In an embodiment, the data processing arrangement 120 is configured to compare the computed impedance with a predefined threshold impedance and determine the weld quality between the busbar 102 and at least one battery cell 104 based on the comparison. The impedance is a sensitive indicator of internal resistance at various points within the battery pack, including the connections between the busbar 102 and the battery cells 104. A high impedance value at the connection points indicates poor or degraded electrical contact, such as weak or inconsistent welding. Further, the comparison of the computed impedance with a predefined threshold enables the data processing arrangement 120 to efficiently detect welding issues with the busbar-to-cell connection, and therefore, perform corrective actions before the occurrence of significant performance degradation or safety hazards occur.
In accordance with a second aspect, there is described a method 200 of determining weld quality between a busbar 102 and at least one battery cell 104 of a battery pack, the method 200 comprises:
- supplying a reference voltage signal across a plurality of battery cells via at least one voltage source 112;
- generating a band-pass voltage digital signal and a band-pass current digital signal, via at least one analog to digital converter 124;
- modulating an amplitude of the band-pass voltage digital signal and band-pass current digital signal, via at least one signal conditioning unit 118;
- computing a magnitude of voltage and current corresponding to the modulated band-pass voltage digital signal and band-pass current digital signal, via a data processing unit 120; and
- computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal, via the data processing unit 120.
Figure 3 describes a method of determining weld quality between a busbar 102 and at least one battery cell 104 of a battery pack. The method 200 starts at a step 202. At the step 202, the method 200 comprises supplying a reference voltage signal across a plurality of battery cells via at least one voltage source 112. At a step 204, the method 200 comprises generating a band-pass voltage digital signal and a band-pass current digital signal, via at least one analog to digital converter 124. At a step 206, the method 200 comprises modulating an amplitude of the band-pass voltage digital signal and band-pass current digital signal, via at least one signal conditioning unit 118. At a step 208, the method 200 comprises computing a magnitude of voltage and current corresponding to the modulated band-pass voltage digital signal and band-pass current digital signal, via a data processing unit 120. At a step 210, the method 200 comprises computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal, via the data processing unit 120.
In an embodiment, the method 200 comprises supplying a reference voltage signal across the plurality of battery cells 104, via the at least one voltage source 112.
In an embodiment, the method 200 comprises sensing a voltage and current signal across the at least one battery cell 104, via the at least one sensing arrangement 114.
In an embodiment, the method 200 comprises receiving the voltage and current signal across the at least one battery cell 104 to the at least one band-pass filter 122.
In an embodiment, the method 200 comprises passing a range of frequencies of the voltage and current signal based on a frequency of the reference voltage signal, via the at least one band-pass filter 122.
In an embodiment, the method 200 comprises receiving the band-pass voltage and current signal, and generating a band-pass voltage digital signal and a band-pass current digital signal, corresponding to the received band-pass voltage and current signal to the at least one analog to digital converter 124.
In an embodiment, the method 200 comprises modulating an amplitude of the generated band-pass voltage digital signal and band-pass current digital signal received from the at least one analog to digital converter 124, via the at least one signal conditioning unit 118.
In an embodiment, the method 200 comprises computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal based on the computed magnitude of the voltage and current, via the data processing arrangement 120.
In an embodiment, the method 200 comprises comparing the computed impedance with a predefined threshold impedance and determining the weld quality between the busbar and at least one battery cell 104 based on the comparison, via the data processing arrangement 120.
In an embodiment, the method 200 comprises supplying a reference voltage signal across the plurality of battery cells 104, via the at least one voltage source 112. Further, the method 200 comprises sensing a voltage and current signal across the at least one battery cell 104, via the at least one sensing arrangement 114. Furthermore, the method 200 comprises computing a torque demand based on the received inputs, via the processing unit 122. Furthermore, the method 200 comprises receiving the voltage and current signal across the at least one battery cell 104 to the at least one band-pass filter 122. Furthermore, the method 200 comprises passing a range of frequencies of the voltage and current signal based on a frequency of the reference voltage signal, via the at least one band-pass filter 122. Furthermore, the method 200 comprises receiving the band-pass voltage and current signal, and generating a band-pass voltage digital signal and a band-pass current digital signal, corresponding to the received band-pass voltage and current signal to the at least one analog to digital converter 124. Furthermore, the method 200 comprises modulating an amplitude of the generated band-pass voltage digital signal and band-pass current digital signal received from the at least one analog to digital converter 124, via the at least one signal conditioning unit 118. Furthermore, the method 200 comprises computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal based on the computed magnitude of the voltage and current, via the data processing arrangement 120. Furthermore, the method 200 comprises comparing the computed impedance with a predefined threshold impedance and determine the weld quality between the busbar and at least one battery cell 104 based on the comparison, via the data processing arrangement 120.
In an embodiment, the method 200 comprises supplying a reference voltage signal across a plurality of battery cells via at least one voltage source 112. Furthermore, the method 200 comprises generating a band-pass voltage digital signal and a band-pass current digital signal, via at least one analog to digital converter 124. Furthermore, the method 200 comprises modulating an amplitude of the band-pass voltage digital signal and band-pass current digital signal, via at least one signal conditioning unit 118. Furthermore, computing a magnitude of voltage and current corresponding to the modulated band-pass voltage digital signal and band-pass current digital signal, via a data processing unit 120. Furthermore, the method 200 comprises computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal, via the data processing unit 120.
Based on the above-mentioned embodiments, the present disclosure provides significant advantages of improved accuracy for determining weld quality between a busbar and at least one battery cell of a battery pack, and thereby, precisely provides precise identification of the welding defects (inconsistency) or degradation in the connection quality over time.
It would be appreciated that all the explanations and embodiments of the system 100 also apply mutatis-mutandis to the method 200.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:WE CLAIM:
1. A system (100) for determining weld quality between a busbar (102) and at least one battery cell (104) of a battery pack (106), the system (100) comprises:
- at least one battery cell array (108) comprising a plurality of battery cells (104), connected via the busbar (102); and
- a fixture (110) configured to hold the at least one battery cell array (108) for determining weld quality, the fixture (110) comprises:
- at least one voltage source (112);
- at least one sensing arrangement (114);
- a signal processing unit (116);
- at least one signal conditioning unit (118); and
- a data processing arrangement (120),
wherein the data processing arrangement (120), when in operation, is configured to compute impedance variation for connections between the busbar (102) and the plurality of battery cells (104).
2. The system (100) as claimed in claim 1, wherein the at least one voltage source (112) is configured to supply a reference voltage signal across the plurality of battery cells (104).

3. The system (100) as claimed in claim 1, wherein the at least one sensing arrangement (114) is configured to sense a voltage and current signal across the at least one battery cell (104).

4. The system (100) as claimed in claim 1, wherein the signal processing unit (116) comprises at least one band-pass filter (122) and at least one analog-to-digital converter (124).

5. The system (100) as claimed in claim 4, wherein the at least one band-pass filter (122) is configured to receive the voltage and current signal across the at least one battery cell (104).

6. The system (100) as claimed in claim 4, wherein the at least one band-pass filter (122) is configured to pass a range of frequencies of the voltage and current signal based on a frequency of the reference voltage signal.

7. The system (100) as claimed in claim 4, wherein the at least one analog to digital converter (124) is configured to receive the band-pass voltage and current signal, and generate a band-pass voltage digital signal and a band-pass current digital signal, corresponding to the received band-pass voltage and current signal.

8. The system (100) as claimed in claim 1, wherein the at least one signal conditioning unit (118) is configured to modulate an amplitude of the generated band-pass voltage digital signal and band-pass current digital signal received from the at least one analog to digital converter (124).

9. The system (100) as claimed in claim 1, wherein the data processing arrangement (120) is configured to compute a magnitude of voltage and current corresponding to the band-pass voltage digital signal and band-pass current digital signal received from the at least one signal conditioning unit (118).

10. The system (100) as claimed in claim 1, wherein the data processing arrangement (120) is configured to compute an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal based on the computed magnitude of the voltage and current.

11. The system (100) as claimed in claim 1, wherein the data processing arrangement (120) is configured to compare the computed impedance with a predefined threshold impedance and determine the weld quality between the busbar and at least one battery cell (104) based on the comparison.

12. A method (200) of determining weld quality between a busbar (102) and at least one battery cell (104) of a battery pack, the method (200) comprises:
- supplying a reference voltage signal across a plurality of battery cells via at least one voltage source (112);
- generating a band-pass voltage digital signal and a band-pass current digital signal, via at least one analog to digital converter (124);
- modulating an amplitude of the band-pass voltage digital signal and band-pass current digital signal, via at least one signal conditioning unit (118);
- computing a magnitude of voltage and current corresponding to the modulated band-pass voltage digital signal and band-pass current digital signal, via a data processing unit (120); and
- computing an impedance and phase shift between the modulated band-pass voltage digital signal and band-pass current digital signal, via the data processing unit (120).

13. The method (200) as claimed in claim 12, the method (200) comprises comparing the computed impedance with a predefined threshold impedance and determining the weld quality between the busbar (102) and at least one battery cell (104) based on the comparison, via the data processing unit (120).