Temperature sensor fault diagnosis method and device, electric drive system and vehicle

Abstract

The invention relates to a temperature sensor fault diagnosis method and device, an electric drive system and a vehicle, and the method comprises the steps: continuously obtaining an accumulated work value of the electric drive system of the vehicle for a temperature sensor in the electric drive system in a diagnosis period when the vehicle condition of the vehicle meets a basic enabling condition, and the temperature variation of the temperature sensor in the diagnosis period; thermodynamic models corresponding to different types of temperature sensors are adopted, and a theoretical acting value associated with the temperature variation or the diagnosis period is determined according to the accumulated acting value, the temperature variation and the diagnosis period; and whether the temperature sensor breaks down or not is judged by comparing the accumulated acting value with the theoretical acting value. Through the method and the device, whether the temperature sensor breaks down or not can be judged by comparing the accumulated acting value with the theoretical acting value according to the type of the temperature sensor in a complex thermal environment of an electric drive system, and the problem that the fault of the temperature sensor is difficult to diagnose effectively is solved.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to a method, apparatus, electric drive system, and vehicle for diagnosing temperature sensor faults. Background Technology

[0002] In the electric drive system of new energy vehicles, temperature sensors are core components for thermal management, power control, and safety protection. The accuracy of their signals directly affects system performance, efficiency, and reliability. To meet the regulatory requirements of on-board diagnostic systems and improve system robustness, fault monitoring of the temperature sensors themselves is essential.

[0003] Existing fault diagnosis methods mostly rely on logical judgments based on sensor signal range, fixed thresholds, or simple rates of change. However, the thermal environment of modern electric drive systems is becoming increasingly complex. The cooling circuit integrates multiple heat sources such as motors and inverters, and is dynamically thermally managed through components such as radiators and water pumps. This makes it difficult to effectively diagnose faults in temperature sensors and increases the likelihood of false alarms.

[0004] There is currently no effective solution to the problem of difficulty in effectively diagnosing temperature sensor faults in related technologies. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, device, electric drive system, and vehicle for effectively diagnosing temperature sensor faults, addressing the aforementioned technical problems.

[0006] Firstly, this embodiment provides a method for diagnosing temperature sensor faults, including:

[0007] When the vehicle condition meets the basic enabling conditions, the cumulative work done by the electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, are continuously acquired.

[0008] Using thermodynamic models corresponding to different types of temperature sensors, the theoretical work value associated with the temperature change or the diagnostic cycle is determined based on the cumulative work value, the temperature change, and the diagnostic cycle.

[0009] By comparing the cumulative work done with the theoretical work done, it can be determined whether the temperature sensor has malfunctioned.

[0010] In some embodiments, the method further includes:

[0011] Based on the heat generation characteristics of the installation location of the temperature sensor in the electric drive system, the temperature sensor is divided into a heat-generating component temperature sensor and a heat-receiving component temperature sensor.

[0012] In some embodiments, continuously acquiring the cumulative work done by the vehicle's electric drive system on the temperature sensors in the electric drive system during a diagnostic cycle includes:

[0013] Based on the temperature change and the heat capacity parameters of the cooling circuit in the electric drive system, the first cumulative work done by the electric drive system on the temperature sensor of the heat-generating component is calculated.

[0014] Based on the diagnostic cycle, the motor power in the electric drive system, and the heat dissipation efficiency of the radiator in the cooling circuit, the second cumulative work done by the electric drive system on the temperature sensor of the heated component is calculated.

[0015] In some embodiments, the step of employing thermodynamic models corresponding to different types of temperature sensors to determine the theoretical work value associated with the temperature change or the diagnostic cycle based on the cumulative work value, the temperature change, and the diagnostic cycle includes:

[0016] Based on the first cumulative work value and the motor thermal efficiency of the electric drive system, a first thermodynamic model corresponding to the temperature sensor of the heat-generating component is constructed.

[0017] The first thermodynamic model outputs a first theoretical work value associated with the temperature change.

[0018] In some embodiments, the step of employing thermodynamic models corresponding to different types of temperature sensors to determine the theoretical work value associated with the temperature change or the diagnostic cycle based on the cumulative work value, the temperature change, and the diagnostic cycle includes:

[0019] Based on the second cumulative work value and the motor thermal efficiency of the electric drive system, a second thermodynamic model corresponding to the temperature sensor of the heated component is constructed.

[0020] The second thermodynamic model outputs a second theoretical work value associated with the diagnostic cycle.

[0021] In some embodiments, determining whether the temperature sensor has malfunctioned by comparing the cumulative work done with the theoretical work done includes:

[0022] When the cumulative work done by the temperature sensor is greater than or equal to the theoretical work done, the temperature sensor is determined to have a viscous fault.

[0023] In some embodiments, the method further includes:

[0024] After the vehicle's power system has been continuously shut down for a preset period of time, the temperature detected by the temperature sensor and the ambient temperature are acquired.

[0025] When the difference between the detected temperature and the ambient temperature exceeds a preset temperature threshold, the temperature sensor is determined to have a deviation fault.

[0026] In some embodiments, the method further includes:

[0027] The voltage signal of the electric drive coolant temperature sensor in the temperature sensor of the heated component is acquired in real time.

[0028] Based on the effective measurement range of the electric drive coolant temperature sensor, combined with the preset ambient temperature limit and aging error parameters, the fault voltage threshold range is dynamically calibrated to obtain the fault voltage threshold range.

[0029] The electrical fault of the electric drive coolant temperature sensor is determined by comparing the voltage signal with the calibrated fault voltage threshold range.

[0030] Secondly, this embodiment provides a temperature sensor fault diagnosis device, including:

[0031] The data acquisition module is used to continuously acquire the cumulative work done by the electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, when the vehicle condition meets the basic enabling conditions.

[0032] The model calculation module is used to determine the theoretical work value associated with the temperature change or the diagnostic cycle by using the thermodynamic model corresponding to different types of temperature sensors, based on the cumulative work value, the temperature change, and the diagnostic cycle.

[0033] The fault diagnosis module is used to determine whether the temperature sensor has malfunctioned by comparing the cumulative work value with the theoretical work value.

[0034] Thirdly, this embodiment provides an electric drive system, including:

[0035] Multiple temperature sensors are installed in the cooling circuit of the electric drive system to monitor the temperature at different locations in the cooling circuit.

[0036] The controller is communicatively connected to the plurality of temperature sensors and is configured to perform the temperature sensor fault diagnosis method described in the first aspect.

[0037] Fourthly, this embodiment provides a vehicle including the electric drive system described in the third aspect above.

[0038] Compared with related technologies, the temperature sensor fault diagnosis method, device, electric drive system, and vehicle provided in this embodiment continuously acquire the cumulative work done by the vehicle's electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, when the vehicle's condition meets the basic enabling conditions. Using thermodynamic models corresponding to different types of temperature sensors, a theoretical work value associated with the temperature change or the diagnostic cycle is determined based on the cumulative work value, the temperature change, and the diagnostic cycle. By comparing the cumulative work value and the theoretical work value, it is determined whether the temperature sensor has failed. This embodiment acquires the cumulative work value of the vehicle's electric drive system and the temperature change of the temperature sensor during the diagnostic cycle, and uses a corresponding thermodynamic model to determine the theoretical work value for the type of temperature sensor. This enables the determination of whether a temperature sensor has failed under the complex thermal environment of the electric drive system, solving the problem of difficulty in effectively diagnosing temperature sensor faults.

[0039] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0040] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0041] Figure 1 This is a hardware structure block diagram of the terminal of a temperature sensor fault diagnosis method in one embodiment;

[0042] Figure 2 This is a flowchart of a temperature sensor fault diagnosis method in one embodiment;

[0043] Figure 3 This is a schematic diagram of the structure of the electric drive system in one embodiment;

[0044] Figure 4 This is a schematic diagram of the electric drive system in another embodiment;

[0045] Figure 5 This is a schematic diagram of the cooling system of the electric drive system in one embodiment;

[0046] Figure 6 This is a diagnostic strategy for the temperature sensor of the heat-generating component in one embodiment;

[0047] Figure 7 This is a diagnostic strategy for the temperature sensor of the heated component in one embodiment;

[0048] Figure 8 This is a flowchart of a temperature sensor fault diagnosis method in another embodiment;

[0049] Figure 9 This is a structural block diagram of a temperature sensor fault diagnosis device in one embodiment.

[0050] In the diagram: 102, processor; 104, memory; 106, transmission device; 108, input / output device; 10, data acquisition module; 20, model calculation module; 30, fault diagnosis module. Detailed Implementation

[0051] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0052] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these” used in this application do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to these processes, methods, products, or devices. Words such as “connected,” “linked,” and “coupled” used in this application are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. Normally, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," "third," etc., used in this application are merely to distinguish similar objects and do not represent a specific order of objects.

[0053] The method embodiments provided in this example can be executed on a terminal, computer, or similar computing device. For example, it can run on a terminal. Figure 1 This is a hardware structure block diagram of the terminal for the temperature sensor fault diagnosis method in this embodiment. For example... Figure 1 As shown, a terminal may include one or more ( Figure 1Only one is shown in the diagram. A processor 102 and a memory 104 for storing data are also included. The processor 102 may be, but is not limited to, a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that… Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the terminal described above. For example, the terminal may also include components that are larger than... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown are illustrated.

[0054] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the temperature sensor fault diagnosis method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0055] The transmission device 106 is used to receive or send data via a network. This network includes a wireless network provided by the terminal's communication provider. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 can be a Radio Frequency (RF) module used for wireless communication with the Internet.

[0056] Existing fault diagnosis methods mostly rely on logical judgments based on sensor signal range, fixed thresholds, or simple rates of change. However, the thermal environment of modern electric drive systems is becoming increasingly complex. The cooling circuit integrates multiple heat sources such as motors and inverters, and is dynamically thermally managed through components such as radiators and water pumps. This makes it difficult to effectively diagnose faults in temperature sensors and increases the likelihood of false alarms.

[0057] This embodiment provides a method for diagnosing temperature sensor faults. Figure 2 This is a flowchart of the temperature sensor fault diagnosis method in this embodiment, as follows: Figure 2As shown, the method includes the following steps:

[0058] Step S201: When the vehicle condition meets the basic enabling conditions, continuously acquire the cumulative work done by the vehicle's electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle.

[0059] Specifically, Figure 3 This is a schematic diagram of the electric drive system in this embodiment, as shown below. Figure 3 As shown, the electric drive system has six sensors, including: a motor temperature sensor, an inverter temperature sensor, a DC-DC converter (DC-DC converter) temperature sensor, a CIDD (Combine of inverter and DC-DC controller) temperature sensor, an electric drive coolant temperature sensor, and an electric drive water pump temperature sensor. In addition, the electric drive system also includes a fan, water pump, radiator, on-board charger, air separator, motor, and the CIDD (inverter and DC-DC controller) combination module. The placement of the temperature sensors and other components in the electric drive system's cooling circuit is as follows: Figure 3 As shown, the arrows in the cooling circuit indicate the flow direction of the coolant. The electric drive coolant temperature sensor is directly connected to the ECU (Electronic Control Unit). The signals from the four temperature sensors—motor temperature sensor, inverter temperature sensor, DC-DC temperature sensor, and CIDD temperature sensor—are output by the IGM (Inverter and Generator Module) through the power CAN (Controller Area Network). The electric drive water pump temperature sensor is output by the LIN (Local Interconnect Network).

[0060] In this embodiment, the temperature sensor fault diagnosis mainly focuses on the rationality diagnosis of the temperature sensor in the aforementioned electric drive system. The purpose of rationality diagnosis is to promptly and accurately reflect the sensor's fault status when a temperature sensor malfunctions, while simultaneously taking measures to minimize the impact of the faulty sensor on the vehicle. Rationality diagnosis includes viscous fault diagnosis, which detects whether the temperature sensor's output signal can promptly follow actual temperature changes.

[0061] When the vehicle meets the basic enabling conditions (such as the electric drive system being powered on, the vehicle's powertrain having been shut down for a sufficiently long time, a significant change in coolant temperature, and no other system faults), the diagnostic program is initiated and performed at certain diagnostic intervals, ensuring that the temperatures of all components of the electric drive system are fully balanced with the environment. The power of the drive system is collected in real time by the motor controller, and the power is integrated within the diagnostic cycle to obtain the cumulative work done by the electric drive system on the temperature sensors during the diagnostic cycle. Simultaneously, the temperature sensor values ​​are read during the diagnostic cycle, and the actual temperature change measured by the temperature sensors during the diagnostic cycle is calculated.

[0062] For example, the basic enabling conditions include: powertrain downtime greater than a threshold of 36,000 seconds; driving cycle activation; minimum energy causing a significant change in coolant temperature greater than a threshold of 4,000 kJ; and minimum electric drive system energy entering diagnostics greater than a threshold of 2,600 kJ when the ambient temperature during monitoring is 3 degrees lower than the temperature at which the driving cycle is activated (the purpose is to prevent the temperature rise from being insignificant due to increased heat dissipation after a sudden drop in ambient temperature).

[0063] Step S202: Using the thermodynamic models corresponding to different types of temperature sensors, determine the theoretical work value associated with the temperature change or the diagnostic cycle based on the cumulative work value, temperature change, and diagnostic cycle.

[0064] Specifically, based on the type of temperature sensor (which is determined in advance or in real time), the corresponding thermodynamic model is invoked. This model takes the temperature change or diagnostic time as input and calculates, in reverse, the minimum amount of energy theoretically required to produce such a temperature change, i.e., the theoretical work value associated with the temperature change or diagnostic time, based on the law of conservation of energy.

[0065] Temperature sensors in electric drive systems are divided into heat-generating component temperature sensors and heat-receiving component temperature sensors. Heat-generating component temperature sensors are configured to monitor the temperature of electrical components that can generate heat themselves, such as inverter temperature sensors, motor temperature sensors, and DC-DC temperature sensors. Heat-receiving component temperature sensors are configured to monitor the temperature of cooling circuit components that do not generate heat themselves or whose heat generation is negligible, such as CIDD temperature sensors, electric drive coolant temperature sensors, and electric drive water pump temperature sensors.

[0066] The heat generated by the electric drive system directly determines the fluctuation of the temperature sensor of the heat-generating component. For the temperature sensor of the heat-receiving component, the temperature rise mainly depends on the heat generated by the electric drive system flowing into the electric drive coolant. However, since there is a heat sink in the electric drive coolant circuit, the heat generated by the electric drive system will be partially lost before it can act on the temperature sensor of the heat-receiving component. Therefore, different thermodynamic models are required for the temperature sensors of the heat-generating component and the temperature sensors of the heat-receiving component.

[0067] Step S203: By comparing the cumulative work value with the theoretical work value, it is determined whether the temperature sensor has malfunctioned.

[0068] Specifically, the cumulative work value is compared with the theoretical work value. If the cumulative work value reaches or exceeds the theoretical work value, it indicates that theoretically, the minimum theoretical work value is required for the temperature sensor to generate the current temperature change. However, if the actual cumulative work value of the electric drive system during the diagnostic cycle exceeds the theoretical work value, the temperature sensor is determined to be faulty.

[0069] Through the above steps, the cumulative work done by the vehicle's electric drive system and the temperature change of the temperature sensor during the diagnostic cycle are obtained. Furthermore, the theoretical work done is determined using a corresponding thermodynamic model based on the type of temperature sensor. This allows for the determination of whether the temperature sensor has malfunctioned based on its type. Compared to existing technologies that rely on sensor signal range, fixed thresholds, or simple rates of change for logical judgment, this embodiment does not depend on a fixed temperature change rate threshold. Instead, it verifies the consistency between the cumulative work done by the electric drive system and the energy demand (theoretical work done) implied by the temperature sensor signal in real time. This fundamentally avoids misjudgments caused by fluctuations in operating conditions. Especially in the complex thermal environment of the electric drive system, it can effectively diagnose temperature sensor faults and reduce false alarms.

[0070] In some embodiments, the method further includes the following steps:

[0071] Based on the heat generation characteristics of the installation location of temperature sensors in electric drive systems, temperature sensors are divided into heat-generating component temperature sensors and heat-receiving component temperature sensors.

[0072] Specifically, during the system design or initialization phase, all temperature sensors are pre-classified based on the physical characteristics of whether the carrier at each temperature sensor's installation location is a primary heat source.

[0073] Temperature sensors for heat-generating components refer to temperature sensors directly mounted on electrical components that consume electrical energy and generate a large amount of Joule heat. Examples include motor temperature sensors (embedded in the motor stator coil, which generates heat when current flows through the coil), inverter temperature sensors (mounted on the inverter's heat sink, where internal power devices generate heat during inverter operation), and DC-DC temperature sensors (mounted in the DC-DC converter housing, where power losses generate heat during converter operation). The temperature of these components is primarily determined by their own operating current.

[0074] Temperature sensors for heated components refer to sensors installed on parts that do not generate heat themselves or whose heat generation is negligible, and whose temperature changes mainly depend on heat transfer from the coolant. Examples include electric drive coolant temperature sensors (usually installed on the coolant manifold, with the temperature determined by the coolant heat exchange process), CIDD temperature sensors, and electric drive water pump temperature sensors (installed on the water pump housing, with the temperature mainly caused by heat transfer from the coolant). Their readings reflect the result of the coolant absorbing and transferring heat.

[0075] This embodiment uses the differences in heat generation characteristics based on the installation location of the temperature sensor in the electric drive system to provide a basis for the application of a differentiated thermodynamic model, making the diagnostic strategy more consistent with the actual working scenario of the temperature sensor.

[0076] In some embodiments, the step S201 described above, which continuously acquires the cumulative work done by the vehicle's electric drive system on the temperature sensor within the diagnostic cycle, includes the following steps:

[0077] Based on the temperature change and the heat capacity parameters of the cooling circuit in the electric drive system, the first cumulative work value of the temperature sensor of the heat-generating component is calculated; based on the diagnostic cycle, the motor power in the electric drive system and the heat dissipation efficiency of the radiator in the cooling circuit, the second cumulative work value of the temperature sensor of the heat-receiving component is calculated.

[0078] Specifically, Figure 4 This is a schematic diagram of the electric drive system in this embodiment, as shown below. Figure 4 As shown, for temperature sensors of heat-generating components (DC-CDC temperature sensors, inverter temperature sensors, and motor temperature sensors), the carrier itself can generate heat. After the heat is generated, it acts directly on the body, causing the temperature to rise. Then the heat flows into the coolant. The worst-case scenario is that the heat generated by the hardware flows completely into the coolant, that is, the heat is completely and evenly distributed in the system shown in the electric drive system (including coolant and electrical components). Therefore, the heat generated by the electric drive system directly determines the fluctuation of the temperature sensor of the heat-generating component.

[0079] Using the measured temperature change ΔT and the heat capacity parameters of the cooling system of the electric drive system, calculate the first cumulative work required for the entire cooling system to produce the temperature change ΔT. The calculation formula can be obtained based on the specific heat capacity formula:

[0080] = c×ρ×V×ΔT;

[0081] Where c is the specific heat capacity of the coolant, ρ is the density of the coolant, and V is the volume of the coolant in the cooling system.

[0082] Figure 5 This is a schematic diagram of the cooling system of the electric drive system in this embodiment, as shown below. Figure 5As shown, this includes a heat sink, a temperature sensor for the heated component, and heat-generating elements (motor, inverter, and DC-DC converter, etc.). For the temperature sensor for the heated component, the carrier itself does not generate heat or generates very little heat; the temperature rise of the sensor mainly relies on the heat generated by the electric drive system flowing into the electric drive coolant. However, because a heat sink is installed in the electric drive coolant circuit, some of the heat generated by the electric drive system is lost before it reaches the temperature sensor for the heated component. Therefore, the heat loss caused by the heat sink's heat dissipation capacity must be considered additionally during fault diagnosis.

[0083] Using the diagnostic cycle, the motor power in the electric drive system, and the heat dissipation efficiency of the radiator in the cooling circuit, calculate the second cumulative work required for the entire cooling system to produce the temperature change ΔT. The calculation formula is as follows:

[0084] ;

[0085] in, t represents the motor power, and t represents time (diagnostic cycle). For motor efficiency, The coefficient for the flow of heat generated by the motor into the coolant. This refers to the heat dissipation efficiency of the radiator.

[0086] By taking into account the difference in temperature changes generated by the temperature sensors of the heat-generating component and the heat-receiving component in this embodiment, the cumulative work done by the temperature sensors during the diagnostic cycle is calculated to provide a basis for the subsequent construction of a differentiated thermodynamic model.

[0087] In some embodiments, step S202 above employs thermodynamic models corresponding to different types of temperature sensors to determine the theoretical work value associated with the temperature change or diagnostic cycle based on the cumulative work value, temperature change, and diagnostic cycle, including the following steps:

[0088] Based on the first cumulative work value and the motor thermal efficiency of the electric drive system, a first thermodynamic model corresponding to the temperature sensor of the heat-generating component is constructed; through the first thermodynamic model, the first theoretical work value associated with the temperature change is output.

[0089] Specifically, the thermal efficiency of the motor based on the electric drive system To generate the first cumulative work value, we need to work backwards. The minimum work required by the motor is calculated by referring to the aforementioned first cumulative work value to construct the first thermodynamic model and then calculating the first theoretical work value. The calculation formula is as follows:

[0090] ;

[0091] Among them, motor efficiency (thermal efficiency) The efficiency can be found based on the current operating conditions using the motor efficiency MAP chart.

[0092] For example, ΔT is considered a significant temperature change; V is 3.5 L; c = 3.47 J / (gK) is the specific heat capacity at 50 degrees Celsius (the water temperature approaches 50 degrees Celsius after prolonged immersion under extreme summer conditions); ρ = 1120 g / L is the density at 50 degrees Celsius; and the motor efficiency... At least 95%. Combining the above calculation formulas, as shown in Table 1, the first cumulative work required for different temperature changes ΔT (°C) can be estimated. (kJ) and the first theoretical work value (KJ), for example, the first cumulative work value corresponding to a temperature change of 1℃. The work done is 13.6 kJ, the first theoretical work value. It is 272 kJ.

[0093] Table 1

[0094]

[0095] By constructing a quantitative first thermodynamic model in this embodiment, the first theoretical work value associated with the temperature change is output, making the theoretical work calculation of the heat-generating sensor more accurate, improving the scientific nature of fault diagnosis, and reducing the risk of misjudgment.

[0096] In some embodiments, step S202 above employs thermodynamic models corresponding to different types of temperature sensors to determine the theoretical work value associated with the temperature change or diagnostic cycle based on the cumulative work value, temperature change, and diagnostic cycle, including the following steps:

[0097] Based on the second cumulative work value and the motor thermal efficiency of the electric drive system, a second thermodynamic model corresponding to the temperature sensor of the heated component is constructed; through the second thermodynamic model, a second theoretical work value associated with the diagnostic cycle is output.

[0098] Specifically, the thermal efficiency of the motor based on the electric drive system To generate a second cumulative work value, we need to work backwards. The minimum work required by the motor is calculated by referring to the second cumulative work value mentioned above to construct a second thermodynamic model and then calculating the second theoretical work value. The calculation formula is as follows:

[0099] ;

[0100] Among them, motor efficiency (thermal efficiency) The efficiency can be found based on the current operating conditions using the motor efficiency MAP chart.

[0101] By constructing a quantified second thermodynamic model in this embodiment, a second theoretical work value associated with the diagnostic cycle is output, making the theoretical work calculation of the heated component sensor more accurate, improving the scientific nature of fault judgment, and reducing the risk of misjudgment.

[0102] In some embodiments, step S203 above, which compares the cumulative work done with the theoretical work done to determine whether the temperature sensor has malfunctioned, includes the following steps:

[0103] When the cumulative work done by the temperature sensor is greater than or equal to the theoretical work done, the temperature sensor is determined to have a viscous fault.

[0104] Specifically, the system compares the cumulative work done by each temperature sensor with its theoretical work done. If the cumulative work done by the temperature sensor is greater than or equal to the theoretical work done, it means that at least the theoretical work done is required for the temperature sensor to produce the current temperature change. However, if the actual cumulative work done by the electric drive system during the diagnostic cycle exceeds the theoretical work done, and the temperature sensor is expected to produce a larger temperature change, then the temperature sensor is determined to have a viscous fault. Furthermore, a tolerance range can be preset; if the difference between the cumulative work done by the temperature sensor and the theoretical work done exceeds this tolerance range, the temperature sensor is determined to have a viscous fault.

[0105] Figure 6 This is the diagnostic strategy for the temperature sensor of the heat-generating component in this embodiment, such as... Figure 6 As shown, when the vehicle condition meets the basic enabling conditions, the motor power of the electric drive system is collected during the diagnostic cycle, and the power is integrated to obtain the first cumulative work value. The first cumulative work value is compared with the first theoretical work value. When the basic enabling conditions are met and the first cumulative work value is greater than or equal to the first theoretical work value, it is determined that the temperature sensor of the heat-generating component has a viscous fault, and a diagnostic enabling signal and related fault information are issued.

[0106] Figure 7 This is the diagnostic strategy for the temperature sensor of the heated component in this embodiment, such as... Figure 7 As shown, when the vehicle's condition meets the basic enabling conditions, the motor power and radiator power of the electric drive system are collected during the diagnostic cycle. The difference between the motor power and radiator power is integrated to obtain a second cumulative work value. This second cumulative work value is compared with a second theoretical work value. When the basic enabling conditions are met and the second cumulative work value is greater than or equal to the second theoretical work value, a viscous fault is determined in the temperature sensor of the heated component, and a diagnostic enabling signal and related fault information are issued. (Reference) Figure 5Since the sensors for the heated components are all located after the radiator in the cooling circuit, under extreme operating conditions (high vehicle speed), the heat generated by the heat-generating components is absorbed by the coolant and dissipated directly through the radiator. As a result, the temperature sensors cannot produce large fluctuations. Therefore, a small tolerance range can be set for fault diagnosis of the temperature sensors for the heated components.

[0107] Furthermore, under high temperature and high vehicle speed conditions, the diagnostic characteristic value is extremely small due to the influence of high heat dissipation and high coolant specific heat capacity, which may cause false alarms. Therefore, under high temperature and high vehicle speed conditions, it is necessary to increase the threshold calibration of the minimum electric drive system energy required to enter the diagnosis in the basic enabling conditions.

[0108] This embodiment clarifies the diagnostic strategy for determining temperature sensor faults, avoiding false triggers caused by minor fluctuations and ensuring the reliability of diagnostic results.

[0109] In some embodiments, the above also includes the following deviation fault diagnosis steps:

[0110] After the vehicle's power system has been continuously shut down for a preset period of time, the temperature sensor detects the temperature and the ambient temperature. When the difference between the detected temperature and the ambient temperature exceeds a preset temperature threshold, it is determined that the temperature sensor has a deviation fault.

[0111] Specifically, this embodiment further diagnoses deviation faults in the rationality diagnosis. Deviation fault diagnosis mainly aims to detect whether the temperature sensor can accurately reflect the ambient temperature at the current location. After the power system has been shut down for a calibration period (e.g., 6-8 hours), the detected temperatures displayed by all temperature sensors are close to or even reach the ambient temperature. If the temperature displayed by the temperature sensor is not near the ambient temperature, and the difference between the detected temperature and the ambient temperature exceeds a preset temperature threshold, it can be considered that the detected temperature of that temperature sensor cannot reflect the ambient temperature at the current sensor location, and a suspicious signal related to the fault information is output.

[0112] This embodiment utilizes the thermal equilibrium state after a long period of parking to provide a simple, effective, and computationally inexpensive method for verifying the static accuracy of sensors. This method complements dynamic viscous diagnosis, forming a more complete sensor health status monitoring system.

[0113] In some embodiments, for the electric drive coolant temperature sensor connected to the ECU, in addition to the rationality diagnosis described in the above embodiments, further electrical diagnosis is required. The specific steps are as follows:

[0114] The voltage signal of the electric drive coolant temperature sensor in the heated component temperature sensor is acquired in real time; based on the effective measurement range of the electric drive coolant temperature sensor, combined with the preset ambient temperature limit and aging error parameters, the fault voltage threshold range is dynamically calibrated; by comparing the voltage signal with the calibrated fault voltage threshold range, it is determined whether the electric drive coolant temperature sensor has experienced an electrical fault.

[0115] Specifically, the controller's analog-to-digital conversion channel samples the output voltage signal of the temperature sensor in real time. Based on the effective measurement range of the temperature sensor, the preset ambient temperature limit, and the aging error, a reasonable voltage signal range is dynamically calculated and calibrated. Specifically, based on the preset ambient temperature limit (lowest possible ambient temperature -50℃), the upper fault limit is calibrated; based on the effective measurement range of the temperature sensor (a known temperature-voltage characteristic curve, e.g., -40℃ to 130℃) and the aging error (e.g., ±2%), the lower fault limit of the fault voltage threshold range is calibrated. Furthermore, based on the upper and lower fault limits, the slope of the temperature-voltage characteristic curve endpoints of the temperature sensor is extended to form a dynamic fault voltage threshold range.

[0116] The acquired voltage signal is continuously compared with the corresponding fault voltage threshold range at this moment. If the voltage signal continues to exceed this range, it is determined that there is an electrical fault (short circuit or open circuit) in the electric drive coolant temperature sensor circuit or in the sensor itself.

[0117] Through real-time and accurate monitoring of the original circuit of the electric drive coolant temperature sensor in this embodiment, the dynamic fault voltage threshold range calibration can better match the nonlinear characteristics of the temperature sensor, accurately identify electrical faults in a wider temperature range, and effectively avoid false alarms caused by normal temperature changes.

[0118] The present embodiment will now be described and illustrated through preferred embodiments.

[0119] Figure 8 This is a flowchart of the temperature sensor fault diagnosis method in this embodiment, as follows: Figure 8 As shown, the method includes the following steps:

[0120] Step S801: Based on the heat generation characteristics of the installation location of the temperature sensor in the vehicle's electric drive system, the temperature sensor is divided into heat-generating component temperature sensor and heat-receiving component temperature sensor.

[0121] Step S802: When the vehicle condition meets the basic enabling conditions, continuously acquire the first cumulative work done by the electric drive system on the temperature sensors of the heat-generating components, the second cumulative work done on the temperature sensors of the heat-receiving components, and the temperature change of each temperature sensor during the diagnostic cycle.

[0122] Step S803: Based on the temperature change and the heat capacity parameters of the cooling circuit in the electric drive system, calculate the first cumulative work value; based on the first cumulative work value and the motor thermal efficiency of the electric drive system, construct the first thermodynamic model corresponding to the temperature sensor of the heat-generating component; through the first thermodynamic model, output the first theoretical work value associated with the temperature change.

[0123] Step S804: Based on the diagnostic cycle, the motor power in the electric drive system, and the heat dissipation efficiency of the radiator in the cooling circuit, calculate the second cumulative work value; based on the second cumulative work value and the motor thermal efficiency of the electric drive system, construct a second thermodynamic model corresponding to the temperature sensor of the heated component; through the second thermodynamic model, output the second theoretical work value associated with the diagnostic cycle.

[0124] Step S805: When the first cumulative work value of the heat-generating component temperature sensor is greater than or equal to the first theoretical work value, it is determined that the heat-generating component temperature sensor has a viscous fault; when the second cumulative work value of the heat-receiving component temperature sensor is greater than or equal to the second theoretical work value, it is determined that the heat-receiving component temperature sensor has a viscous fault.

[0125] Step S806: After the vehicle's power system has been continuously shut down for a preset time, the detected temperature of the temperature sensor and the ambient temperature are acquired; when the difference between the detected temperature and the ambient temperature exceeds a preset temperature threshold, it is determined that the temperature sensor has a deviation fault.

[0126] Step S807: Based on the effective measurement range of the electric drive coolant temperature sensor, combined with the preset ambient temperature limit and aging error parameters, the fault voltage threshold range is dynamically calibrated; by comparing the voltage signal of the electric drive coolant temperature sensor with the calibrated fault voltage threshold range, it is determined whether the electric drive coolant temperature sensor has experienced an electrical fault.

[0127] It should be noted that the steps shown in the above flowchart or the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here. For example, step S807 performs electrical fault diagnosis for the electric drive coolant temperature sensor; this step is not necessary for other temperature sensors.

[0128] This embodiment also provides a temperature sensor fault diagnosis device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. The terms "module," "unit," "subunit," etc., used below refer to combinations of software and / or hardware that implement a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0129] Figure 9 This is a structural block diagram of the temperature sensor fault diagnosis device in this embodiment, as shown below. Figure 9 As shown, the device includes:

[0130] The data acquisition module 10 is used to continuously acquire the cumulative work done by the electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, when the vehicle condition meets the basic enabling conditions.

[0131] The model calculation module 20 is used to determine the theoretical work value associated with the temperature change or the diagnostic cycle by using the thermodynamic model corresponding to different types of temperature sensors, based on the cumulative work value, temperature change, and diagnostic cycle.

[0132] The fault diagnosis module 30 is used to determine whether the temperature sensor has malfunctioned by comparing the cumulative work value with the theoretical work value.

[0133] The device provided in this embodiment acquires the cumulative work done by the vehicle's electric drive system and the temperature change of the temperature sensor during the diagnostic cycle. Furthermore, it uses a corresponding thermodynamic model to determine the theoretical work done based on the type of temperature sensor. This allows the device to determine whether the temperature sensor has malfunctioned based on its type. Compared to existing technologies that rely on sensor signal range, fixed thresholds, or simple rates of change for logical judgment, this embodiment does not depend on a fixed temperature change rate threshold. Instead, it verifies the consistency between the cumulative work done by the electric drive system and the energy demand (theoretical work done) implied by the temperature sensor signal in real time. This fundamentally avoids misjudgments caused by fluctuations in operating conditions. Especially in the complex thermal environment of the electric drive system, it can effectively diagnose temperature sensor malfunctions and reduce false alarms.

[0134] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0135] refer to Figure 3This embodiment provides an electric drive system, including: a fan, a water pump, a radiator, an on-board charger, an air separator, a motor, an inverter, and a DC-DC controller assembly module. Multiple temperature sensors are installed at key locations in the cooling circuit (such as the motor stator, inverter IGBTs, coolant inlet and outlet, and water pump), namely, a motor temperature sensor, an inverter temperature sensor, a DC-DC temperature sensor, a CIDD temperature sensor, an electric drive coolant temperature sensor, and an electric drive water pump temperature sensor. These sensors are connected to a central controller (such as a motor controller) via a CAN bus, LIN bus, or analog lines. This controller is programmed to internally store and run the software for the temperature sensor fault diagnosis method described in the above embodiment.

[0136] This embodiment provides a vehicle, specifically a hybrid electric vehicle or a pure electric vehicle including the electric drive system described in the above embodiment, and thus has the ability to perform intelligent, accurate, and full-condition fault self-diagnosis of its electric drive system temperature sensor.

[0137] Among them, the electric motors of hybrid vehicles support pure electric mode, series mode, and parallel mode.

[0138] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0139] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0140] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or alternative to other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0141] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for diagnosing faults in a temperature sensor, characterized in that, include: When the vehicle condition meets the basic enabling conditions, the cumulative work done by the vehicle's electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, are continuously acquired. Using thermodynamic models corresponding to different types of temperature sensors, the theoretical work value associated with the temperature change or the diagnostic cycle is determined based on the cumulative work value, the temperature change, and the diagnostic cycle. By comparing the cumulative work done with the theoretical work done, it can be determined whether the temperature sensor has malfunctioned.

2. The temperature sensor fault diagnosis method according to claim 1, characterized in that, The method further includes: Based on the heat generation characteristics of the installation location of the temperature sensor in the electric drive system, the temperature sensor is divided into a heat-generating component temperature sensor and a heat-receiving component temperature sensor.

3. The temperature sensor fault diagnosis method according to claim 2, characterized in that, The continuous acquisition of the cumulative work done by the vehicle's electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle includes: Based on the temperature change and the heat capacity parameters of the cooling circuit in the electric drive system, the first cumulative work done by the electric drive system on the temperature sensor of the heat-generating component is calculated. Based on the diagnostic cycle, the motor power in the electric drive system, and the heat dissipation efficiency of the radiator in the cooling circuit, the second cumulative work done by the electric drive system on the temperature sensor of the heated component is calculated.

4. The temperature sensor fault diagnosis method according to claim 3, characterized in that, The thermodynamic model employing different types of temperature sensors determines the theoretical work value associated with the temperature change or the diagnostic cycle based on the cumulative work value, the temperature change, and the diagnostic cycle, including: Based on the first cumulative work value and the motor thermal efficiency of the electric drive system, a first thermodynamic model corresponding to the temperature sensor of the heat-generating component is constructed. The first thermodynamic model outputs a first theoretical work value associated with the temperature change.

5. The temperature sensor fault diagnosis method according to claim 3, characterized in that, The thermodynamic model employing different types of temperature sensors determines the theoretical work value associated with the temperature change or the diagnostic cycle based on the cumulative work value, the temperature change, and the diagnostic cycle, including: Based on the second cumulative work value and the motor thermal efficiency of the electric drive system, a second thermodynamic model corresponding to the temperature sensor of the heated component is constructed. The second thermodynamic model outputs a second theoretical work value associated with the diagnostic cycle.

6. The temperature sensor fault diagnosis method according to any one of claims 1 to 5, characterized in that, The step of determining whether the temperature sensor has malfunctioned by comparing the cumulative work value with the theoretical work value includes: When the cumulative work done by the temperature sensor is greater than or equal to the theoretical work done, the temperature sensor is determined to have a viscous fault.

7. The temperature sensor fault diagnosis method according to claim 1, characterized in that, The method further includes: After the vehicle's power system has been continuously shut down for a preset period of time, the temperature detected by the temperature sensor and the ambient temperature are acquired. When the difference between the detected temperature and the ambient temperature exceeds a preset temperature threshold, the temperature sensor is determined to have a deviation fault.

8. The temperature sensor fault diagnosis method according to claim 2, characterized in that, The method further includes: The voltage signal of the electric drive coolant temperature sensor in the temperature sensor of the heated component is acquired in real time. Based on the effective measurement range of the electric drive coolant temperature sensor, combined with the preset ambient temperature limit and aging error parameters, the fault voltage threshold range is dynamically calibrated to obtain the fault voltage threshold range. The electrical fault of the electric drive coolant temperature sensor is determined by comparing the voltage signal with the calibrated fault voltage threshold range.

9. A temperature sensor fault diagnosis device, characterized in that, include: The data acquisition module is used to continuously acquire the cumulative work done by the electric drive system on the temperature sensor in the electric drive system during the diagnostic cycle, as well as the temperature change of the temperature sensor during the diagnostic cycle, when the vehicle condition meets the basic enabling conditions. The model calculation module is used to determine the theoretical work value associated with the temperature change or the diagnostic cycle by using the thermodynamic model corresponding to different types of temperature sensors, based on the cumulative work value, the temperature change, and the diagnostic cycle. The fault diagnosis module is used to determine whether the temperature sensor has malfunctioned by comparing the cumulative work value with the theoretical work value.

10. An electric drive system, characterized in that, include: Multiple temperature sensors are installed in the cooling circuit of the electric drive system to monitor the temperature at different locations in the cooling circuit. The controller is communicatively connected to the plurality of temperature sensors and is configured to perform the temperature sensor fault diagnosis method as described in any one of claims 1 to 8.

11. A vehicle, characterized in that, Including the electric drive system as described in claim 10.

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