Online real-time monitoring system for internal resistance of power battery

Abstract

The invention relates to an on-line real-time monitoring system for internal resistance of a power battery. The on-line real-time monitoring system comprises an alternating current excitation source, an alternating current coupler, a standard resistor, a measuring end front end circuit and a digital phase-locked measuring device. And a secondary coil of the alternating current coupler and the standard resistor are connected in series in a main loop with a power battery and a main load. A main loop current measurement channel connected to the two ends of the standard resistor is scanned in a two-dimensional space constructed by two dimensions of a frequency point and a phase, a frequency point and phase combination enabling the correlation degree to be maximum is obtained, and a main loop instantaneous current signal is obtained; for a battery voltage measurement channel connected to two ends of the power battery, directly setting a frequency point of the battery voltage measurement channel as a frequency point measured by the main loop current measurement channel, and then searching a phase value enabling the correlation degree to be maximum in a one-dimensional space; and by combining the actually measured main loop instantaneous current signal and the synchronously actually measured battery instantaneous voltage signal, the actually measured data of the instantaneous battery internal resistance are obtained.

Description

Technical Field

[0001] The present invention relates to the field of power battery technology and weak signal detection technology, and in particular to an online real-time monitoring system for the internal resistance of a power battery. Background Art

[0002] With the popularity of new energy electric vehicles, power batteries (especially lithium batteries) are being used more and more widely. The performance and health of power batteries will change over time and with usage, so continuous monitoring and maintenance are essential. Real-time monitoring of battery performance indicators through power battery testing technology can extend the life of the battery and reduce possible failures and losses. The performance of power batteries is affected by multiple parameters, so multiple indicators need to be measured during testing. Common parameters include voltage, current, temperature, capacity, and internal resistance.

[0003] Among them, the internal resistance of the battery is an important characteristic indicator used to reflect the performance of the battery, which has an important impact on the working state of the battery and the output of electric energy. By measuring the internal resistance, key performance parameters such as the load capacity, capacity, self-discharge rate and cycle life of the battery can be evaluated. Further identifying the change pattern of the internal resistance of the battery can help to identify the health status of the battery in advance, extend the battery life, avoid severe accidents such as battery explosion, or issue a warning in time before the accident occurs to avoid casualties. However, compared with other common power battery parameters, the internal resistance of the battery is a physical quantity that is difficult to measure online in real time. In the prior art, the scheme for measuring the internal resistance of the power battery is often carried out offline, or detected during the charging process. For example, in the scenario where the vehicle is charged after being stationary, the internal resistance of the battery is calculated using the changes in the detected battery voltage and current values. However, the above measurement scheme makes it difficult to monitor the internal resistance of the battery while the car is driving.

[0004] New energy vehicles will face a lot of complex working conditions during driving. For example, environmental factors such as temperature, humidity, vibration, etc. may affect the performance of the power battery, thereby interfering with the internal resistance measurement results. Furthermore, during driving, the voltage and current at both ends of the battery are in a complex dynamic change process, and the asynchrony of voltage and current measurement, coupled with the complex interference caused by various working conditions, makes it extremely difficult to accurately detect the internal resistance of the battery.

[0005] Chinese patent application CN115290980A proposes an online monitoring method and system for the internal resistance of an electric vehicle power battery. This scheme is based on the voltage and current values ​​at the current moment in a set time period, and adopts a recursive method with a forgetting factor to avoid the calculation deviation caused by the asynchronous sampling of the battery voltage and current, thereby calculating the internal resistance value of the power battery in the set time period. However, in this scheme, the calculated battery internal resistance value is essentially an estimated value based on a recursive algorithm, rather than actual measured data. And the real-time performance of measuring the internal resistance of the battery needs to be further improved. Furthermore, the various interferences caused by the large number of complex working conditions faced by the car during driving will also affect the accuracy of online monitoring of the battery internal resistance.

[0006] On the other hand, the prior art also uses the AC injection method to measure the internal resistance of the battery. In one solution, an AC signal of a certain frequency is injected into the main circuit where the battery and the main load are located based on a constant current source, and then the internal resistance of the battery is obtained by measuring the response signal of the frequency. However, the excitation signal of this solution is a sinusoidal signal with a DC component, which will cause a large power consumption and is not suitable for long-term monitoring during the driving process of the car. In addition, this solution cannot solve the problem of interference to the measurement caused by a large number of complex working conditions.

[0007] In summary, the market urgently needs a solution that can perform online real-time measurement of the internal resistance of power batteries under complex working conditions. Summary of the invention

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a solution capable of performing online real-time measurement of the internal resistance of a power battery under complex working conditions.

[0009] In order to solve the above technical problems, the present invention provides an online real-time monitoring system for the internal resistance of a power battery, characterized in that it includes: an AC excitation source, an AC coupler, a standard resistor, a measuring end analog differential pre-circuit, and a digital phase-locked measurement device; wherein the AC excitation source is used to generate an AC excitation signal, and the AC excitation signal is an analog signal with a preset operating frequency, the AC coupler includes a primary coil and a secondary coil coupled based on mutual inductance effect, the primary coil is connected to the AC excitation source to form an excitation signal loop, the secondary coil and the standard resistor are both connected in series in a main loop having a power battery and a main load, the measuring end analog differential pre-circuit and the digital phase-locked measurement device constitute a measuring end circuit, and the measuring end circuit includes at least two measurement channels, which are a main loop current measurement channel connected to both ends of the standard resistor and a main loop current measurement channel connected to the power battery. The battery voltage measurement channel at both ends of the battery; the digital phase-locked measurement device includes an analog-to-digital conversion unit and an anti-noise phase-locked measurement unit. For the main loop current measurement channel, scanning is performed in a two-dimensional space constructed by the two dimensions of frequency and phase to obtain a frequency and phase combination that maximizes the correlation, thereby obtaining a function of the voltage signal at both ends of the standard resistor changing with time, and then based on the known resistance value of the standard resistor, obtaining a function of the main loop current signal changing with time; for the battery voltage measurement channel, its frequency is directly set to the frequency measured by the main loop current measurement channel, and then a phase value that maximizes the correlation is searched in a one-dimensional space to obtain a function of the battery voltage signal changing with time; the function of the battery internal resistance changing with time is obtained by combining the measured function of the main loop current signal changing with time and the synchronously measured function of the battery voltage signal changing with time.

[0010] The analog differential preamplifier circuit at the measuring end includes an analog differential circuit, an analog filtering circuit, an analog amplifier circuit and a power supply circuit for power supply.

[0011] Among them, the measurement end circuit also includes a main load voltage measurement channel connected to both ends of the main load. In the main load voltage measurement channel, the frequency point is directly set to the frequency point measured by the main loop current measurement channel, and then the phase value that maximizes the correlation is searched in one-dimensional space, thereby obtaining a function of the main load voltage signal changing with time; combining the measured function of the main loop current signal changing with time and the synchronously measured function of the main load voltage signal changing with time, a function of the main load internal resistance changing with time is obtained.

[0012] Among them, for the main loop current measurement channel, in the two-dimensional space constructed by the two dimensions of frequency and phase, the frequency search interval is set within a narrowband spectrum range, and the narrowband spectrum is a spectrum interval of plus or minus 3% centered on the excitation signal frequency.

[0013] Wherein, the excitation signal frequency is one or more frequency points selected within the range of 150 Hz to 20000 Hz.

[0014] Among them, the online real-time monitoring system for the internal resistance of the power battery also includes a shielding shell, the AC coupler and the standard resistor are both installed in the shielding shell, the AC excitation source and the measuring end analog differential pre-circuit are electrically connected to the AC coupler and the standard resistor in the shielding shell through a cable with a shielding layer, and the cable is connected to the shielding shell through a special terminal with the function of shielding external electromagnetic interference.

[0015] The AC excitation source sets a plurality of operating frequency bands, and adaptively switches the operating frequency bands to avoid interference signals based on the recognition result of the vehicle driving characteristics-battery internal resistance abnormality recognition model; the recognition model is an AI model for describing the mapping relationship between the power battery internal resistance feature vector and the vehicle driving feature vector; the recognition model is obtained by collecting data of a large number of users' real driving processes, and performing iterative training and optimization based on a neural network algorithm; the recognition model is used to identify what kind of vehicle driving feature vector will cause abnormal changes in the battery internal resistance; the vehicle driving feature vector is set as the input vector of the recognition model, and the power battery internal resistance feature vector is set as the input vector of the recognition model. The output vector of the recognition model; the vehicle driving feature vector is a feature vector constructed by a feature combination that describes the driving state and the use state of the cabin electrical appliances based on various driving behaviors, driving modes, driving scenes, and environmental variables such as temperature and humidity; the power battery internal resistance feature vector is constructed based on multiple feature variables extracted from the abnormal waveform of the measured function of the battery internal resistance changing with time; among the abnormal waveforms of the measured function of the battery internal resistance changing with time, it is assumed that those abnormal waveforms whose battery internal resistance values ​​can be restored are caused by interference signals. When the recognition result of the recognition model is that an interference signal is currently present, the AC excitation source adaptively switches the working frequency band.

[0016] Among them, the power of the AC excitation source includes a main gear and a power enhancement gear, the main gear is configured as the default working gear and uses low power; and when the vehicle driving state is identified as having a high battery health risk or prone to interference signals, the AC excitation source adaptively switches to the power enhancement gear; wherein, according to the vehicle driving characteristics-battery internal resistance abnormality recognition model, it is identified whether the vehicle has entered a driving state with a high battery health risk or prone to interference signals.

[0017] Among them, in the vehicle driving characteristic vector, the driving behavior includes: one or more of sudden braking, sudden acceleration, frequent speed changes, high-speed driving, sudden turns, energy recovery, uphill, downhill and other driving behaviors that cause current jumps in the main circuit; the driving mode is a control mode preset by the vehicle itself to adapt to various driving styles, and the control mode includes: one or more of normal mode, comfort mode, sports mode, economy mode, snow mode, and off-road mode; the driving scene includes: one or more of normal roads, slippery roads, off-road scenes, and snow scenes; wherein the normal road and the slippery road are further divided into road types, and the road types include: highways, urban roads and mountain roads.

[0018] Compared with the prior art, the present invention has at least one of the following technical effects:

[0019] 1. The present application can realize high-precision real-time synchronous measurement of battery internal resistance, obtain instantaneous voltage and instantaneous current data with high synchronization, thereby obtaining the measured data of instantaneous battery internal resistance, and then obtain the function of battery internal resistance changing with time.

[0020] 2. In some embodiments of the present application, an AC signal is injected into the main circuit in a coupled manner based on the mutual inductance effect, and high-precision real-time synchronous measurement is achieved based on digital phase-locked measurement technology. This enables high-accuracy real-time measurement of the battery internal resistance with low power consumption while the vehicle is in motion.

[0021] 3. In some embodiments of the present application, the AC coupler and the standard resistor are integrated in the same shielding shell, which can not only prevent electromagnetic interference caused by various electrical activities of the vehicle driving and electrical appliances in the cabin, but also reduce the space occupied by the online real-time monitoring system of the power battery internal resistance.

[0022] 4. In some embodiments of the present application, based on the online real-time monitoring data of the internal resistance of the power battery, the vehicle driving characteristics that affect the battery health can be extracted and identified, thereby helping to avoid or reduce situations that have a negative impact on the battery health, thereby improving the battery life and enhancing safety.

[0023] 5. During the actual driving of electric vehicles, changes in motor power will have a direct impact on the main circuit, causing current fluctuations in the main circuit. The use of various cabin electrical appliances may also affect the main circuit through complex electrical activity mechanisms, causing a certain degree of current fluctuations in the main circuit. Sometimes the frequency of these fluctuations or some of the frequency components of these fluctuations may be close to the frequency of the injected AC signal, causing interference to the battery internal resistance monitoring. In some embodiments of the present application, the above-mentioned interference can also be suppressed based on the vehicle driving characteristic vector (i.e., various characteristic information related to the actual state of the battery, load and discharge circuit acquired synchronously during vehicle driving) and the AI ​​model, thereby improving the anti-interference ability of the battery internal resistance monitoring.

[0024] 6. In some embodiments of the present application, interference signals can be avoided by setting multiple operating frequency bands for the AC excitation source and adaptively switching the operating frequency bands based on the recognition results, thereby further improving the anti-interference capability and measurement accuracy of the battery internal resistance monitoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the circuit structure of an online real-time monitoring system for the internal resistance of a power battery in one embodiment of the present application is shown;

[0026] Figure 2 A schematic diagram of a logic diagram of an analog differential preamplifier circuit in one embodiment of the present application is shown;

[0027] Figure 3 A schematic diagram of the circuit structure of an analog differential preamplifier circuit in one embodiment of the present application is shown;

[0028] Figure 4 A schematic diagram of the circuit structure of an analog differential circuit in an embodiment of the present application is shown;

[0029] Figure 5 A schematic diagram of the circuit structure of an analog filter circuit in one embodiment of the present application is shown;

[0030] Figure 6 A schematic diagram of the circuit structure of an analog amplifier circuit in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0031] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] It should be noted that in this specification, the expressions of first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Therefore, without departing from the teaching of this application, the first subject discussed below can also be referred to as the second subject.

[0033] In the drawings, the thickness, size and shape of objects have been slightly exaggerated for ease of explanation. The drawings are only examples and are not drawn strictly to scale.

[0034] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, wholes, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0035] As used herein, the terms "substantially," "approximately," and similar terms are used as terms of approximation, not degree, and are intended to account for the inherent variations in measurements or calculations that would be recognized by those of ordinary skill in the art.

[0036] Unless otherwise defined, all terms (including technical terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having the same meaning as they have in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense, unless explicitly defined in this article.

[0037] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0039] The purpose of this application is to attempt to solve the problem of online real-time monitoring of the internal resistance of electric vehicle power batteries, and then to perform more efficient health management of the power batteries based on the real-time monitoring results of the internal resistance, so as to extend the battery life and reduce safety risks.

[0040] refer to Figure 1According to one embodiment of the present application, a power battery internal resistance online real-time monitoring system is provided, which includes: an AC excitation source, an AC coupler, a standard resistor, a measurement end analog differential pre-circuit, and a digital phase-locked measurement device. Among them, the AC excitation source is used to generate an AC excitation signal, which is an analog signal, usually a sine wave of a preset frequency. The AC coupler includes a primary coil and a secondary coil coupled based on the mutual inductance effect. The primary coil is connected to the AC excitation source to form an excitation signal loop, and the secondary coil is arranged in the main loop, and the current carrying capacity of the secondary coil is consistent with the cable of the main loop (or, the current carrying capacity of the secondary coil can reach the current carrying capacity of the cable in the main loop). The main loop is the main working loop of the car, which includes a power battery and a main load of the car. The main load can be, for example, or can include a motor winding for driving the car. The secondary coil and the standard resistor are all connected in series in the main loop. In other words, the main loop at least includes a power battery, a secondary coil, a standard resistor and a main load connected in series. Furthermore, in this embodiment, the analog differential preamplifier circuit and the digital phase-locked measurement device are used to construct a measurement circuit. The measurement circuit includes at least two measurement channels, namely, a main loop current measurement channel connected to both ends of a standard resistor and a battery voltage measurement channel connected to both ends of a power battery.

[0041] Specifically, in the main loop current measurement channel, the two ends of the standard resistor are connected as input ends to the measurement end analog differential preamplifier circuit, referring to Figure 2 and Figure 3 , the analog differential preamplifier circuit at the measuring end includes an analog differential circuit, an analog filtering circuit, and an analog amplifier circuit, and then outputs the signal to the digital phase-locked measurement device. The analog differential preamplifier circuit at the measuring end may further include a power supply circuit for supplying power to the analog differential circuit, the analog filtering circuit, and the analog amplifier circuit, respectively. The digital phase-locked measurement device includes a high-precision sampling unit (i.e., a high-precision analog-to-digital conversion unit) and an anti-noise phase-locked measurement unit. The anti-noise phase-locked measurement unit can be implemented based on the scheme recorded in Chinese patent CN201110380805.X, so as to obtain the frequency (referring to the frequency point, which can be referred to as the frequency point), phase, and amplitude of the measured signal (i.e., the main circuit current signal). Among them, the correlation refers to the correlation between the reference signal and the measured signal. Specifically, the reference signal here is a digital signal set by the digital phase-locked measurement device that is consistent with the waveform of the excitation signal (for example, the waveforms are all sinusoidal waves) and whose frequency value and phase value are within the set search space range. The measured signal is the signal obtained by sampling after being processed by the analog differential preamplifier circuit at the measuring end and drawn from both ends of the standard resistor. In this embodiment, the specific meanings of concepts such as correlation, reference signal, and measured signal are consistent with the records in CN201110380805.X. For more detailed content, please refer to CN201110380805.X, which will not be repeated here.

[0042] In the battery voltage measurement channel, the two ends of the power battery are connected to the analog differential pre-circuit of the measurement end as input ends. The analog differential pre-circuit of the measurement end includes an analog differential circuit, an analog filtering circuit, and an analog amplification circuit, and then the signal is output to the digital phase-locked measurement device. The digital phase-locked measurement device includes a high-precision sampling unit (i.e., a high-precision analog-to-digital conversion unit) and an anti-noise phase-locked measurement unit. The anti-noise phase-locked measurement unit can also be implemented based on the scheme recorded in Chinese patent CN201110380805.X. However, it should be noted that in the battery voltage measurement channel, the frequency of the battery voltage directly uses the frequency value measured in the main loop current measurement channel, and then based on the frequency value, the phase value that maximizes the correlation is searched in the phase space, thereby obtaining the phase and amplitude of the battery voltage. Among them, the correlation refers to the correlation between the reference signal and the measured signal. Here, the reference signal is a digital signal set by the digital phase-locked measurement device that is consistent with the excitation signal waveform and whose frequency value and phase value are within the set search space range. The measured signal is the signal derived from the two ends of the power battery, processed by the analog differential front-end circuit at the measuring end, and then sampled (i.e., analog-to-digital conversion) to obtain the signal.

[0043] Furthermore, the anti-noise phase-locked measurement unit calculates the impedance of the battery based on the measured main circuit current signal and battery voltage signal. It should be noted that in this embodiment, the main circuit current signal and battery voltage signal measured by the anti-noise phase-locked measurement unit are both complex numbers including real and imaginary parts, and the measured results are functions that change over time. Therefore, the measured internal resistance of the battery is also an impedance function including an imaginary part. At any time point, the amplitude of the impedance function is extracted to obtain the measured value of the internal resistance of the battery at that time point.

[0044] The above-mentioned embodiment measures the internal resistance of the battery based on the AC injection method. In contrast, in the prior art, the AC injection method usually connects an AC excitation source to the main circuit to inject an excitation signal when the car is stationary. This is because the instantaneous voltage of the battery is easily submerged by noise during the driving of the car. In other words, the existing measurement scheme based on the AC injection method is difficult to achieve real-time measurement of the internal resistance of the battery while the car is driving. Moreover, even when the car is stationary, in order to improve the noise resistance, the AC excitation source often generates a sinusoidal signal with a DC component, which causes the excitation signal to generate additional energy consumption, which is not conducive to long-term real-time monitoring of the internal resistance of the battery.

[0045] In the above-mentioned embodiment of the present application, based on the mutual inductance effect, the AC excitation voltage signal is injected from the excitation circuit into the main circuit through the AC coupler, and the excitation signal can have no DC component (or greatly reduce the DC component), so that the additional energy consumption brought by measuring the internal resistance of the battery can be reduced. On the other hand, at the measurement end, the present application uses a digital phase-locked measurement device to perform high-precision digital scanning of the actual frequency and phase of the measurement channel, and determines the actual frequency and phase based on the principle of maximizing the correlation. Here, the actual frequency and phase of the measurement channel are the frequency and phase of the actual AC signal injected into the main circuit for measuring the internal resistance of the battery. Since the frequency of the excitation source (i.e., the excitation signal frequency) is known in the excitation circuit. Therefore, at the measurement end, the digital phase-locked measurement device can directly use the frequency of the excitation source as the center, set a narrowband spectrum as the search interval, and the search step size can be appropriately reduced, so that the density of the searched frequency points is increased, thereby obtaining a more accurate measurement result. In some embodiments, the search of frequency and phase can be realized based on the scheme recorded in Chinese patent CN201110380805.X. In the Chinese patent CN201110380805.X, the anti-noise frequency measurement within the broadband range can be performed on both ends of the standard resistor based on the same method in this embodiment. The only difference is that the search range can be narrowed from broadband to narrowband based on the excitation source frequency, while increasing the density of the searched frequency points. Furthermore, in this embodiment, when measuring the voltage signal at both ends of the battery, the frequency point is no longer searched, but the frequency point measured by the main loop current measurement channel is directly used. That is to say, in the digital phase-locked measurement algorithm of this embodiment, the frequency points of the main loop current measurement channel and the battery voltage measurement channel are locked. The search for phase in the battery voltage measurement channel is consistent with the scheme of Chinese patent CN201110380805.X. In this embodiment, the narrowband spectrum set by the digital phase-locked measurement device can be a narrowband spectrum within the range of plus or minus 1% of the excitation signal frequency. The excitation signal frequency can be 150Hz, for example. In some other embodiments, considering the possible impact of more complex electrical activities during the driving and use of electric vehicles, the narrowband spectrum can be appropriately relaxed. For example, the narrowband spectrum can be set to a spectrum range of plus or minus 3% of the excitation signal frequency.

[0046] In the above embodiment, for the main loop current measurement channel, that is, the measurement channel connected to the two ends of the standard resistor, it is actually scanned in the two-dimensional space constructed by the two dimensions of frequency and phase to obtain the frequency and phase combination that maximizes the correlation, thereby determining the actual frequency, and then deriving the function of the voltage signal at both ends of the standard resistor changing with time. Since the resistance value of the standard resistor is known, the function of the current signal passing through the standard resistor changing with time can be further calculated, that is, the function of the main loop current signal changing with time. For the battery voltage measurement channel, the frequency is directly locked to the frequency measured by the main loop current measurement channel, and then the phase value that maximizes the correlation is searched in the one-dimensional space, and then the function of the battery voltage signal changing with time is obtained. In this embodiment, the high-precision multi-channel joint measurement based on the anti-noise phase-locked measurement unit can well compensate for the frequency drift caused by the signal injection method based on the mutual inductance effect, and can suppress the interference caused by the injected signal and other electrical activities inside the battery and the noise signals caused by various working conditions during the vehicle driving process. The weak signal that can reflect the internal resistance of the battery is extracted and measured from both ends of the standard resistor and the power battery in real time with extremely high accuracy, thereby obtaining a function of the change of the battery internal resistance over time. In other words, this embodiment can measure the instantaneous voltage signal and instantaneous current signal of the power battery, and then analyze the internal resistance of the battery at each specific moment, with extremely high real-time performance.

[0047] In this application, since the real-time measurement of the power battery internal resistance is significantly enhanced, it is possible (or potential) to associate the dynamic change of the battery internal resistance with the specific working conditions during the driving process of the electric vehicle, and then analyze the relationship between the driving mode, driving scene, working condition type, driver's operating habits and other factors and the change of the battery internal resistance (for example, real-time monitoring of the battery internal resistance, identification of its abnormal changes and real-time diagnosis and analysis of the abnormal changes), and then integrate the analysis results into technologies such as intelligent driving and intelligent cockpits, and directly or indirectly intervene in various driving behaviors and / or various power consumption behaviors in the intelligent cockpit, which will help to improve the battery life and improve the safety of the battery. A more detailed description will be given below in conjunction with specific embodiments.

[0048] Further, in one embodiment of the present application, the online real-time monitoring system for the internal resistance of the power battery may also include a shielding shell, which can shield the electromagnetic signal outside the shell. The AC coupler and the standard resistor are both installed in the shielding shell, and the AC excitation source and the measurement end analog differential pre-circuit can be electrically connected to the AC coupler and the standard resistor in the shielding shell through a cable with a shielding layer. Among them, the cable can be connected to the shielding shell through a dedicated terminal with a function of shielding external electromagnetic interference. In this embodiment, the AC coupler and the standard resistor are integrated in the same shielding shell, which can not only prevent the electromagnetic interference caused by various electrical activities of the electrical appliances in the car and the cabin, but also reduce the space occupied by the online real-time monitoring system for the internal resistance of the power battery. Further, a radiator can be arranged inside and / or outside the shielding shell. Since the secondary coils of the standard resistor and the AC coupler are both located in the main circuit, the current passing through may be large, and the installation of a radiator helps to prevent the temperature in the shielding shell from being too high, and avoids the secondary coils of the standard resistor and the AC coupler from causing measurement deviations due to excessive temperature. In particular, it avoids deviations caused by excessive temperature of the standard resistor.

[0049] Further, in one embodiment of the present application, in the online real-time monitoring system of the internal resistance of the power battery, the measuring end circuit may also include a third measurement channel, namely, a main load voltage measurement channel connected to both ends of the main load. That is to say, in this embodiment, the measuring end circuit includes three measurement channels: a main loop current measurement channel connected to both ends of the standard resistor, a battery voltage measurement channel connected to both ends of the power battery, and a main load voltage measurement channel connected to both ends of the main load. In the main load voltage measurement channel, both ends of the main load are connected as input ends to the measuring end analog differential pre-circuit, which includes an analog differential circuit, an analog filtering circuit, and an analog amplification circuit, and then outputs the signal to the digital phase-locked measurement device. The digital phase-locked measurement device includes a high-precision sampling unit (i.e., a high-precision analog-to-digital conversion unit) and an anti-noise phase-locked measurement unit. The anti-noise phase-locked measurement unit can also be implemented based on the solution recorded in Chinese patent CN201110380805.X. It should be noted that in the main load voltage measurement channel, the frequency of the main load voltage directly uses the frequency value measured in the main loop current measurement channel described above, and then based on the frequency value, the phase value that maximizes the correlation is searched in the phase space, thereby obtaining the phase and amplitude of the battery voltage. In this way, the function of the main load voltage signal changing with time can be obtained, and combined with the function of the main loop current signal changing with time measured in the previous text, the function of the main load impedance changing with time can be further obtained. In other words, based on this embodiment, not only the instantaneous impedance value of the battery internal resistance can be measured, but also the instantaneous impedance value of the main load can be measured. Based on the measured instantaneous impedance value of the main load, combined with intelligent driving and intelligent cockpit technology, the influence of the main load on the battery internal resistance measurement during the driving of the car can be better analyzed, and then the measurement of the battery internal resistance can be optimized to improve its accuracy. Based on the measurement results of the main load voltage measurement channel, some interference factors that affect the battery internal resistance measurement can be identified, so as to facilitate the adoption of measures to avoid interference. For example, the use of digital phase-locked measurement devices can obtain the signal-to-noise ratio of the main circuit current, the voltage across the battery and the voltage across the main load in real time, and then measure the original interference information. The power battery and the main load are monitored synchronously, and the information of the resistance and signal-to-noise ratio of the two over time is independently obtained. External interference is judged and identified based on common mode characteristics. Based on the difference information of one increase and the other decrease and the trend of stable evolution over time, it can assist in more accurate positioning of the source of internal interference or fault, that is, whether the source of interference or fault comes from inside the battery, inside the main load, or from the main discharge circuit.

[0050] Below, based on a series of embodiments, it is further described how to combine intelligent driving and intelligent cockpit technologies to optimize the online real-time monitoring system for the internal resistance of the power battery of the present application.

[0051] Existing studies have shown that an increase in the internal resistance of a battery is often associated with battery aging or degradation. Therefore, in real-time monitoring of the internal resistance of a battery, an increase in the internal resistance of the battery can be used as a basis for determining whether it is abnormal. Specifically, in this embodiment, a function of how the internal resistance of the battery changes over time can be obtained based on real-time monitoring during vehicle driving. If an abnormal waveform appears in the function of how the internal resistance of the battery changes over time, and the battery internal resistance cannot be restored after the increase, it is determined that the battery health state has declined. If an abnormal waveform appears, but the battery internal resistance increases and then returns to its original value within a certain period of time, then it can be determined that the abnormal waveform is caused by interference in the measurement, and the battery health state can still be considered normal.

[0052] Further, in one embodiment of the present application, a set of feature combinations describing the driving state and the use state of the cabin electrical appliances can be constructed based on various driving behaviors, driving modes, driving scenes, and environmental variables such as temperature and humidity. For the convenience of description, this set of feature combinations can be referred to as vehicle driving feature vectors. Among them, driving behaviors may include, for example, sudden braking, sudden acceleration, frequent speed changes, high-speed driving, sharp turns, energy recovery, uphill and downhill, etc. These driving behaviors may cause a more drastic current jump in the main circuit, thereby affecting the internal resistance of the battery. It should be noted that driving behaviors are not limited to the above types, and the vehicle driving feature vector may also include any other driving behaviors that may cause current jumps. Driving mode refers to the control mode (such as the control mode of brakes, throttles and other electronic control devices) preset by the vehicle itself to adapt to various driving styles. Driving modes may include, for example: normal mode, comfort mode, sports mode, economic mode, snow mode, off-road mode, etc. Driving scenes may include normal roads, slippery roads, off-road scenes, snow scenes, etc. Under road scenes, they can be further divided into: highways, urban roads, mountain roads, etc. On the other hand, the vehicle driving feature vector may also include one or more features for describing the use of high-power electrical appliances, such as the use of high-power electrical appliances such as vehicle air conditioners, vehicle refrigerators, high-power audio equipment, and vehicle projectors.

[0053] Furthermore, based on the above-mentioned vehicle driving characteristic vector, an AI model is constructed to describe the mapping relationship between the internal resistance of the power battery and the vehicle driving characteristic vector. Data of a large number of users' real driving processes are collected, and the AI ​​model is iteratively trained and optimized based on the neural network algorithm to obtain an optimized AI model. In this embodiment, the AI ​​model is mainly used to identify what kind of vehicle driving characteristic vector will cause abnormal changes in the internal resistance of the battery, so the AI ​​model can be called a vehicle driving characteristic-battery internal resistance abnormality recognition model. When the battery health state decreases, the user can be reminded through the smart cockpit, and prompted which driving behaviors are associated with the current battery health state decrease, prompting the user to change the driving behavior or the use of high-power electrical appliances, so that the vehicle driving feature combination that causes the battery health state to decrease (that is, the combination of those features of the various elements of the vehicle driving feature vector) is decoupled, thereby avoiding the battery life reduction or damage caused by the user's driving behavior or the use of high-power electrical appliances.

[0054] On the other hand, during the actual driving of electric vehicles, changes in motor power will have a direct impact on the main circuit, causing current fluctuations in the main circuit. The use of various cabin electrical appliances may also affect the main circuit through complex electrical activity mechanisms, causing a certain degree of current fluctuations in the main circuit. Sometimes the frequency of these fluctuations or some of the frequency components of these fluctuations may be close to the frequency of the injected AC signal, causing interference to the battery internal resistance monitoring. Based on the above analysis, in some embodiments of the present application, the above interference can also be suppressed based on the vehicle driving characteristic vector and the AI ​​model, thereby improving the anti-interference ability of the battery internal resistance monitoring.

[0055] Specifically, in one embodiment, a vehicle driving feature vector, an AI model based on a neural network, and an output vector for describing the change in battery internal resistance are constructed. The vehicle driving feature vector may be composed of all or part of the feature variables of the various driving behaviors, driving modes, driving scenes, and environmental variables such as temperature and humidity mentioned above. The output vector may be composed of a series of feature variables describing the abnormal waveforms of the measured battery internal resistance function. In one example, it can be assumed that those abnormal waveforms whose internal resistance values ​​can be restored are caused by interference signals. In this way, the correlation between the vehicle driving feature vector and the interference signal can be established. Based on the actual driving data of a large number of users, the AI ​​model that reflects the correlation between the vehicle driving feature vector and the interference signal can be continuously trained and optimized. Based on the optimized AI model, the appearance of vehicle driving feature vectors that may cause interference signals can be avoided or reduced as much as possible (for example, in an intelligent driving state), thereby improving the anti-interference ability of battery internal resistance monitoring. In this embodiment, in the measured curve of the battery internal resistance changing with time (i.e., the curve corresponding to the battery internal resistance function, which is sometimes referred to as the battery internal resistance curve below for ease of description), when the internal resistance value increases irreversibly, it can be inferred that the battery health has deteriorated; and when the internal resistance value of the battery internal resistance changing with time increases and then decreases to a value that is basically the same as the original value, the event that causes the abnormal waveform can be regarded as an event in which the internal resistance value can be restored, and it can be further inferred that the event is caused by an interference signal. In this embodiment, the method for identifying and extracting abnormal waveforms in the battery internal resistance curve can refer to the method for identifying and extracting abnormal waveforms in bioelectronic signals in the medical field. For example, the graphic features of the electrocardiogram include: P wave, QRS complex, ST segment and T wave, etc. In the medical field, the changes in these graphic features can reflect the health status of different parts of the heart. In this embodiment, based on the AI ​​model and neural network algorithm, a certain mapping relationship can be established with the health status of the battery internal resistance by analyzing a series of graphic features of the abnormal waveform in the battery internal resistance curve, so as to more accurately analyze the specific type of events that cause the battery health to deteriorate and the vehicle driving characteristics associated with this type of event (i.e., the various driving behaviors, driving modes, driving scenes, and environmental variables such as temperature and humidity described above). In the basic implementation scheme, only the irreversible rise of the battery internal resistance can be used as the basis for identifying the deterioration of the battery health, thereby identifying the specific type of events that cause the battery health to deteriorate and the vehicle driving characteristics associated with this type of event.Furthermore, in another scheme, some waveform features associated with abnormal battery internal resistance (i.e., graphic features similar to abnormal waveforms of electrocardiograms) can be extracted based on big data analysis, and then the deterioration of battery health can be identified based on these waveform features, thereby identifying specific types of events that cause the deterioration of battery health and those vehicle driving characteristics associated with such types of events.

[0056] In another embodiment, the anti-interference ability of the battery internal resistance monitoring can also be improved by setting a backup frequency. Specifically, in the online real-time monitoring system of the power battery internal resistance, the AC excitation source can prepare multiple (at least two) working frequencies, one of which is the main frequency, and the main frequency has a high matching degree with the analog differential front-end circuit of the receiving end. For example, for the main frequency, the analog differential front-end circuit can have a higher signal-to-noise ratio, so as to better improve the performance of weak signal detection. The other is a backup frequency, which is also within the working frequency band of the analog differential front-end circuit, but the signal-to-noise ratio may be slightly lower than the main frequency. When the battery internal resistance monitoring interference is identified, the frequency of the AC excitation source is switched from the main frequency to the backup frequency. When the corresponding feature combination (i.e., the vehicle driving feature vector that causes the interference signal) disappears, the frequency of the AC excitation source is switched from the backup frequency back to the main frequency. There can be more than one backup frequency, as long as it is within the working frequency band of the analog differential front-end circuit and has a sufficient distance from the main frequency to avoid the interference signal. This solution can not only ensure that the battery internal resistance monitoring system has better weak signal detection performance in most situations at most times through the main frequency, but also avoid interference with the battery internal resistance monitoring in special situations at a few times (the interference here mainly refers to the interference signal close to the operating frequency of the monitoring system caused by driving behavior or the use of high-power electrical appliances acting on the main circuit through complex electrical mechanisms, resulting in main circuit current fluctuations), thereby comprehensively improving the accuracy of battery internal resistance monitoring.

[0057] Furthermore, in one embodiment of the present application, the power of the AC excitation source can be adjusted according to actual conditions. For example, the power of the AC excitation source can be divided into several gears, and the main gear uses a lower power to save energy when monitoring the battery internal resistance for a long time; and in vehicle driving and use scenarios where the battery health risk is high or interference signals are prone to appear, an enhanced gear with higher power can be used to help improve the signal-to-noise ratio, so as to more accurately measure the instantaneous battery internal resistance or improve the anti-interference ability of the battery internal resistance measurement. The identification of whether there is a battery health risk and whether an interference signal appears can be achieved based on an AI model. The construction, training and optimization of the AI ​​model can refer to the previous embodiments and will not be repeated here.

[0058] Furthermore, in one embodiment of the present application, a specific implementation scheme of the analog differential preamplifier circuit at the measuring end is also provided. As mentioned above, the analog differential preamplifier circuit at the measuring end includes an analog differential circuit, an analog filtering circuit and an analog amplifying circuit. Figure 4 In this embodiment, the analog differential circuit includes a pre-conditioning unit and a differential amplifier unit. The signal input terminal A and the signal input terminal B are respectively used to receive the voltage signals at both ends of the monitored element (for example, at both ends of a standard resistor or at both ends of a power battery). After passing through the pre-conditioning unit, the two voltage signals are respectively input into the negative input terminal and the positive input terminal of the differential amplifier unit, and the differential amplifier unit outputs an analog differential signal V diff . The pre-conditioning unit includes two sub-modules with circuit symmetry, and the two sub-modules are respectively arranged at the signal input terminal A and the signal input terminal B. The circuit symmetry determines the amplitude of the residual common-mode interference of the amplified signal. The worse the circuit symmetry, the smaller its common-mode rejection ratio, and the worse the ability to suppress common-mode signals. In this embodiment, each sub-module of the pre-conditioning unit includes an operational amplifier U1 or U3, a feedback resistor R3 or R4, a grounding resistor R1 or R2 connected to the negative input terminal of the operational amplifier, and an output resistor R7 or R8 connected between the output terminal and the differential amplifier unit. The differential amplifier unit includes an operational amplifier U4 and a feedback resistor R5. In this embodiment, the two sub-modules of the pre-conditioning unit have exactly the same circuit structure and electrical components. After the pre-conditioning unit, differential amplification is performed. The common-mode part of the voltage signal at both ends of the monitored element can be greatly suppressed, and the differential-mode signal is greatly amplified.

[0059] In this embodiment, the analog filtering circuit is implemented by a state variable filter. The state variable filter is also called a KHN filter, which uses two integrators and an adder to generate a second-order low-pass, band-pass and high-pass response. Figure 5 In this embodiment, the adder is composed of an operational amplifier U2, a feedback resistor R10 connected to the negative input terminal of the operational amplifier, and a resistor connected to the positive input terminal of the operational amplifier and the differential signal V diffThe first integrator is composed of an operational amplifier U6 and a feedback capacitor C9, and the positive input of the operational amplifier is grounded; the second integrator is also composed of an operational amplifier U7 and a feedback capacitor C10, and the positive input of the operational amplifier is grounded. The output of the first integrator is connected to the negative input of the op amp of the adder through the first connection resistor R12, the output of the adder is connected to the negative input of the op amp of the second integrator through the second connection resistor R15, the output of the second integrator is connected to the negative input of the op amp of the first integrator through the third connection resistor R16, and the output of the second integrator is connected to the positive input of the op amp of the adder through the fourth connection resistor R14. In this embodiment, the positive input of the op amp of the adder serves as the input of the entire analog filter circuit (the differential signal of the previous stage is input to the positive input of the op amp of the adder via the input resistor R13). The output of the second integrator serves as the output of the entire analog filter circuit V filter , used to output the filtered analog signal to the next-stage analog amplifier circuit. In one embodiment, the operating frequency of the AC excitation source can be set to 150 Hz, and accordingly, the state variable filter can be a band-stop filter with a second-order band-stop frequency response curve, which can have a 33 Hz to 100 Hz band-stop frequency response curve to filter out 33 Hz to 100 Hz interference signals that are easily generated by vehicle motors and various types of vehicle-mounted electrical appliances.

[0060] Furthermore, in one embodiment, in the state variable filter, by adjusting the values ​​of each resistor and capacitor, various frequency response curves can be designed. And changing the position of the input and output terminals can flexibly obtain a second-order low-pass, band-pass, band-stop or high-pass frequency response curve. Therefore, by setting the values ​​of each resistor and capacitor and changing the position of its input and output terminals, the state variable filter can be set to have multiple optional operating modes. Figure 2In this embodiment, for example, the state variable filter can be configured to have a variety of optional frequency response curves, including: a low-pass frequency response curve with a cutoff frequency of 33Hz, a band-stop frequency response curve of 33Hz to 100Hz, a band-pass frequency response curve of 100Hz to 3kHz, a band-pass frequency response curve of 3k to 15kHz, and a high-pass frequency response curve with a cutoff frequency of 15kHz, which respectively correspond to a low-pass filter working mode with a cutoff frequency of 33Hz, a band-stop filter working mode of 33Hz to 100Hz, a band-pass filter working mode of 100Hz to 3kHz, a band-pass filter working mode of 3k to 15kHz, and a high-pass filter working mode with a cutoff frequency of 15kHz. Accordingly, the AC excitation source can set multiple operating frequencies in different frequency bands. For example, the main operating frequency can be set in the 100Hz to 3kHz frequency band, and an alternative operating frequency can be set in the 3k to 15kHz frequency band and the 15kHz to 20kHz frequency band (the operating frequency is generally between 150Hz and 20kHz). In actual operation, after the operating frequency is selected, the state variable filter adaptively matches the operating mode with the corresponding frequency response curve.

[0061] refer to Figure 6 In this embodiment, the analog amplifier circuit includes an operational amplifier, a feedback resistor, and a grounding resistor connected to the positive input terminal of the operational amplifier. The negative input terminal of the operational amplifier receives the output signal of the analog filter circuit, and the output terminal V out Connect the digital lock-in measurement device.

[0062] In this article, the main circuit current signal, the battery voltage signal and the main load voltage signal all refer to the response signals generated by the injection of the AC signal.

[0063] In the aforementioned embodiments, the online real-time monitoring of the internal resistance of the power battery of an electric vehicle is described as an example, but it should be noted that the online real-time monitoring solution of the internal resistance of the power battery of the present application can also be applied to other high-power and complex working conditions equipment that requires the use of power batteries (such as mining electric machinery equipment that requires the use of power batteries).

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. An online real-time monitoring system for internal resistance of a power battery, characterized in that: include: AC excitation source, AC coupler, standard resistor, analog differential preamplifier circuit at the measurement end, and digital phase-locked measurement device; Wherein, the AC excitation source is used to generate an AC excitation signal, and the AC excitation signal is an analog signal with a preset working frequency. The AC coupler includes a primary coil and a secondary coil coupled based on mutual inductance effect. The primary coil is connected to the AC excitation source to form an excitation signal loop. The secondary coil and the standard resistor are connected in series in a main loop having a power battery and a main load. The measuring end analog differential preamplifier circuit and the digital phase-locked measurement device constitute a measuring end circuit. The measuring end circuit includes at least two measurement channels, which are a main loop current measurement channel connected to both ends of the standard resistor and a battery voltage measurement channel connected to both ends of the power battery. The digital phase-locked measurement device includes an analog-to-digital conversion unit and an anti-noise phase-locked measurement unit. For the main loop current measurement channel, a two-dimensional space constructed by the two dimensions of frequency and phase is scanned to obtain a frequency and phase combination that maximizes the correlation, thereby obtaining a function of the voltage signal across the standard resistor over time, and then obtaining a function of the main loop current signal over time based on the known resistance value of the standard resistor; For the battery voltage measurement channel, its frequency point is directly set to the frequency point measured by the main loop current measurement channel, and then the phase value that maximizes the correlation is searched in the one-dimensional space, thereby obtaining the function of the battery voltage signal changing with time; combining the measured function of the main loop current signal changing with time and the synchronously measured function of the battery voltage signal changing with time, the function of the battery internal resistance changing with time is obtained.

2. The online real-time monitoring system for internal resistance of a power battery according to claim 1, characterized in that: The measuring end analog differential preamplifier circuit comprises an analog differential circuit, an analog filtering circuit, an analog amplifying circuit and a power supply circuit for power supply.

3. The online real-time monitoring system for internal resistance of a power battery according to claim 1, characterized in that: The measurement end circuit also includes a main load voltage measurement channel connected to both ends of the main load. In the main load voltage measurement channel, the frequency point is directly set to the frequency point measured by the main loop current measurement channel, and then a phase value that maximizes the correlation is searched in one-dimensional space to obtain a function of the main load voltage signal changing with time; the function of the main loop current signal changing with time measured and the function of the main load voltage signal changing with time obtained by synchronous measurement are combined to obtain a function of the main load internal resistance changing with time.

4. The online real-time monitoring system for internal resistance of a power battery according to claim 1, characterized in that: For the main loop current measurement channel, in the two-dimensional space constructed by the frequency and phase dimensions, the frequency search interval is set within a narrowband spectrum range, and the narrowband spectrum is a spectrum interval of plus or minus 3% centered on the excitation signal frequency.

5. The online real-time monitoring system for internal resistance of a power battery according to claim 4, characterized in that: The excitation signal frequency is one or more frequency points selected within the range of 150 Hz to 20,000 Hz.

6. The online real-time monitoring system for internal resistance of a power battery according to claim 1, characterized in that: The online real-time monitoring system for the internal resistance of a power battery also includes a shielding shell, the AC coupler and the standard resistor are both installed in the shielding shell, the AC excitation source and the measuring end analog differential pre-circuit are electrically connected to the AC coupler and the standard resistor in the shielding shell through a cable with a shielding layer, and the cable is connected to the shielding shell through a special terminal with the function of shielding external electromagnetic interference.

7. The online real-time monitoring system for internal resistance of a power battery according to claim 1, characterized in that: The AC excitation source is provided with a plurality of operating frequency bands, and adaptively switches the operating frequency bands based on the recognition result of the vehicle driving characteristic-battery internal resistance abnormality recognition model to avoid interference signals; The recognition model is an AI model used to describe the mapping relationship between the power battery internal resistance feature vector and the vehicle driving feature vector; the recognition model is obtained by collecting data from a large number of users' real driving processes and performing iterative training and optimization based on a neural network algorithm; the recognition model is used to identify what kind of vehicle driving feature vector will cause abnormal changes in the battery internal resistance; The vehicle driving feature vector is set as the input vector of the recognition model, and the power battery internal resistance feature vector is set as the output vector of the recognition model; the vehicle driving feature vector is a feature vector constructed by a set of feature combinations describing the driving state and the use state of the cabin electrical appliances based on various driving behaviors, driving modes, driving scenes, and environmental variables such as temperature and humidity; the power battery internal resistance feature vector is constructed based on multiple feature variables extracted from the abnormal waveform of the measured function of the battery internal resistance changing with time; Among the abnormal waveforms of the measured function of the battery internal resistance changing with time, it is assumed that those abnormal waveforms whose battery internal resistance values ​​can be restored are caused by interference signals. When the recognition result of the recognition model is that an interference signal currently exists, the AC excitation source adaptively switches the working frequency band.

8. The online real-time monitoring system for internal resistance of a power battery according to claim 7, characterized in that: The power of the AC excitation source includes a main gear and a power enhancement gear, the main gear is configured as a default working gear and uses low power; when it is identified that the vehicle is in a driving state with a high battery health risk or prone to interference signals, the AC excitation source adaptively switches to the power enhancement gear; wherein, according to the vehicle driving characteristics-battery internal resistance abnormality recognition model, it is identified whether the vehicle has entered a driving state with a high battery health risk or prone to interference signals.

9. The online real-time monitoring system for internal resistance of a power battery according to claim 7 or 8, characterized in that: In the vehicle driving feature vector, the driving behavior includes: one or more of sudden braking, sudden acceleration, frequent speed changes, high-speed driving, sudden turns, energy recovery, uphill, downhill and other driving behaviors that cause current jumps in the main circuit; the driving mode is a control mode preset by the vehicle itself to adapt to various driving styles, and the control mode includes: one or more of normal mode, comfort mode, sports mode, economy mode, snow mode, and off-road mode; the driving scene includes: one or more of normal roads, slippery roads, off-road scenes, and snow scenes; wherein the normal road and the slippery road are further divided into road types, and the road types include: highways, urban roads and mountain roads.

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