Temperature estimation method and device, vehicle and equipment

Abstract

The invention provides a temperature estimation method and device, a vehicle and equipment, relates to the technical field of automobiles, and can realize accurate estimation and active protection of the working temperature of a bus film capacitor in a motor controller of a new energy vehicle, reduce the development cost, improve the measurement precision and prolong the service life of the capacitor on the premise of not needing additional hardware. The reliability of a vehicle power system is guaranteed. The method comprises the following steps: acquiring a ripple voltage and a ripple current of a bus thin-film capacitor, and determining an estimated temperature value of the bus thin-film capacitor based on the ripple voltage and the ripple current.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to temperature estimation methods, devices, vehicles, and equipment. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the reliability and safety of vehicle power systems have become a core focus. In the motor controller of new energy vehicles, the thin-film capacitor at the DC bus terminal is a core component for energy buffering and filtering, and its operating temperature directly determines the system's operational stability.

[0003] Existing technologies rely on implanting measuring devices near the capacitor or making judgments or predictions based on fixed boundary conditions. Therefore, temperature monitoring solutions for busbar thin-film capacitors have significant technical defects and are difficult to meet the complex operating conditions of new energy vehicles. This not only increases the cost of hardware materials but also damages the original sealing structure of the capacitor, resulting in problems such as large measurement errors and high response delays. Summary of the Invention

[0004] This application provides a temperature estimation method, apparatus, vehicle, and equipment that enables accurate estimation and active protection of the operating temperature of the bus film capacitor in the motor controller of a new energy vehicle without the need for additional hardware. This reduces development costs, improves measurement accuracy, and extends the service life of the bus film capacitor.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, this application provides a temperature estimation method, the method comprising:

[0007] The ripple voltage and ripple current of the bus thin film capacitor are obtained. Based on the ripple voltage and ripple current, the estimated temperature value of the bus thin film capacitor is determined. The ripple voltage is the instantaneous fluctuation amplitude of the DC bus voltage, and the ripple current is the AC current component flowing through the bus thin film capacitor.

[0008] The solution provided in this application obtains the ripple voltage and ripple current of the busbar film capacitor. Based on the ripple voltage and ripple current, the estimated temperature value of the busbar film capacitor is determined without the need for additional sensor implantation, thus avoiding damage to the sealed structure of the busbar film capacitor and reducing hardware costs. The temperature is derived by using ripple parameters and ESR, and the estimation accuracy is improved by combining aging compensation. This solves the problems of large errors and slow response in existing solutions, accurately captures capacitor temperature, ensures stable operation of motor controller, and is suitable for the complex operating conditions of new energy vehicles.

[0009] One possible implementation method for determining the estimated temperature value of the busbar thin film capacitor based on ripple voltage and ripple current can be specifically implemented as follows: calculate the equivalent series resistance value of the busbar thin film capacitor based on the ripple voltage and ripple current, and obtain the estimated temperature value of the busbar thin film capacitor based on the equivalent series resistance.

[0010] Based on the above technical means, by utilizing the strong correlation between the equivalent series resistance calculated using ripple parameters and capacitor temperature, the accuracy of temperature estimation is ensured, solving the problems of large errors and slow response in existing solutions, and providing a reliable temperature monitoring basis for the stable operation of motor controllers.

[0011] Another possible implementation is to obtain the estimated temperature value of the bus thin film capacitor based on the equivalent series resistance. Specifically, this can be achieved by finding the temperature value corresponding to the equivalent series resistance from the equivalent series resistance-temperature relationship curve of the bus thin film capacitor, and then obtaining the estimated temperature value.

[0012] Based on the above technical means, the temperature is obtained by directly matching the calculated equivalent series resistance value with the pre-stored equivalent series resistance-temperature relationship curve, which simplifies the temperature derivation process and improves the response speed. The curve is calibrated to ensure accurate mapping relationship, reduce intermediate calculation errors, make the estimated temperature more in line with reality, provide a reliable basis for graded protection, and ensure system stability.

[0013] Another possible implementation is to obtain the ripple voltage and ripple current of the bus thin-film capacitor. Specifically, this can be achieved by: determining the zero-vector time period corresponding to the bus thin-film capacitor, which is the period when the bus thin-film capacitor becomes the main charging and discharging path; during the zero-vector time period, collecting the bus voltage and three-phase current of the bus thin-film capacitor, where the bus voltage refers to the voltage value of the DC bus and the three-phase current refers to the current values ​​of the U / V / W phases of the motor; calculating the ripple voltage based on the bus voltage and the ripple current based on the three-phase current.

[0014] Based on the above technical means, by locking the zero vector period for data acquisition, interference from other circuits is reduced, ensuring more accurate acquisition of ripple voltage and current; the parameters calculated based on this can truly reflect the capacitor state, improve the accuracy of subsequent temperature estimation, provide a reliable basis for protection strategies, adapt to complex operating conditions, and ensure system stability.

[0015] Another possible implementation is to determine the zero vector period corresponding to the bus thin film capacitor. Specifically, when the vehicle enters the braking and power generation mode, the motor speed is greater than or equal to 500 rpm, and the pulse width modulation drive signal is a zero vector command of 000 or 111, the zero vector period corresponding to the bus thin film capacitor is determined. The zero vector command is a drive command in which all the switching transistors of the inverter are in the same on or off state, so that the output voltage vector is zero.

[0016] Based on the above technical means, by clarifying the combined conditions of vehicle braking and power generation, motor speed ≥500rpm and PWM command, the zero vector period of the capacitor as the main charging and discharging path is accurately locked, reducing interference from non-target periods, ensuring that the collected voltage and current data can truly reflect the capacitor state, providing a high-quality foundation for subsequent ripple parameter calculation and temperature estimation, and improving the reliability and adaptability of the solution.

[0017] Another possible implementation is that this application provides a temperature estimation method, which can be specifically implemented as follows: performing compensation calculations on the estimated temperature value to obtain the actual estimated temperature value.

[0018] Based on the above technical means, by compensating for the estimated temperature value, the temperature estimation deviation caused by capacitor aging can be corrected, making the actual estimated temperature more consistent with the true state of the capacitor; avoiding misjudgment caused by aging, ensuring the accurate triggering of subsequent graded protection strategies, improving the system's ability to control the capacitor state, and ensuring the long-term stable operation of the motor controller.

[0019] Another possible implementation is to perform compensation calculations on the estimated temperature value to obtain the actual estimated temperature value. Specifically, this can be achieved by performing compensation calculations on the estimated temperature value based on the aging compensation coefficient to obtain the actual estimated temperature value.

[0020] Based on the above technical means, by correcting the estimated temperature value through the aging compensation coefficient, the influence of the equivalent series resistance deviation caused by the aging of the bus film capacitor on the temperature estimation can be offset, making the actual estimated temperature more consistent with the actual working state of the capacitor; avoiding temperature misjudgment caused by aging, ensuring the accurate triggering of subsequent graded protection strategies, ensuring the long-term stable operation of the motor controller, and adapting to the full life cycle usage needs of the capacitor.

[0021] Another possible implementation is to calculate the estimated temperature value based on the aging compensation coefficient to obtain the actual estimated temperature value. Specifically, the estimated temperature value is corrected based on the aging compensation coefficient, which is the ratio of the current equivalent series resistance value of the bus film capacitor to the initial equivalent series resistance value, used to characterize the aging degree of the bus film capacitor. The arithmetic mean of a preset number of corrected estimated temperature values ​​is taken as the actual estimated temperature.

[0022] Based on the above technical means, the estimated temperature is corrected by the aging compensation coefficient, which accurately reflects the impact of capacitor aging on temperature; then the average value of the corrected temperature after a preset number of times is taken to reduce the fluctuation error of a single sampling, so that the actual estimated temperature is closer to the real state, providing an accurate basis for graded protection and ensuring the long-term stable operation of the motor controller.

[0023] Another possible implementation is that this application provides a temperature estimation method, which can be specifically implemented as: classifying the protection of the busbar film capacitor based on the actual estimated temperature value of the busbar film capacitor.

[0024] Based on the above technical means, a graded protection strategy is adopted, and gradient measures are taken according to the actual estimated temperature. This can ensure the safety of the capacitor in a timely manner at high temperatures, while avoiding excessive protection from affecting the function of the whole vehicle. The protection response is precisely matched with the temperature state, which improves the system safety and operational stability and adapts to the complex operating conditions of new energy vehicles.

[0025] Secondly, this application provides a temperature estimation device, the device comprising: an acquisition module for acquiring the ripple voltage and ripple current of a bus thin film capacitor, wherein the ripple voltage is the instantaneous fluctuation amplitude of the DC bus voltage and the ripple current is the AC current component flowing through the bus thin film capacitor; and an analysis module for determining the estimated temperature value of the bus thin film capacitor based on the ripple voltage and ripple current.

[0026] The acquisition module is also used to determine the zero-vector period corresponding to the bus film capacitor. The zero-vector period refers to the period when the bus film capacitor becomes the main charging and discharging path. During the zero-vector period, the bus voltage and three-phase current of the bus film capacitor are collected. The bus voltage refers to the voltage value of the DC bus. The ripple voltage is calculated based on the bus voltage, and the ripple current is calculated based on the three-phase current.

[0027] Acquisition module: It is also used to determine the zero vector period corresponding to the bus thin film capacitor when the whole vehicle enters the braking and power generation mode, the motor speed is greater than or equal to 500 rpm, and the pulse width modulation drive signal is a zero vector command of 000 or 111. The zero vector command is a drive command in which all the switching transistors of the inverter are in the same on or off state, so that the output voltage vector is zero.

[0028] Analysis module: It is also used to calculate the equivalent series resistance of the bus thin film capacitor based on the ripple voltage and ripple current, and to obtain the estimated temperature value of the bus thin film capacitor based on the equivalent series resistance.

[0029] Analysis module: It is also used to find the temperature value corresponding to the equivalent series resistance from the equivalent series resistance-temperature relationship curve corresponding to the bus film capacitor based on the equivalent series resistance, and obtain the estimated temperature value.

[0030] Analysis module: It is also used to perform compensation calculations on the estimated temperature value to obtain the actual estimated temperature value.

[0031] Analysis module: It is also used to perform compensation calculations on the estimated temperature value based on the aging compensation coefficient to obtain the actual estimated temperature value.

[0032] Analysis module: It is also used to correct the estimated temperature value based on the aging compensation coefficient. The aging compensation coefficient is the ratio of the current equivalent series resistance value of the bus film capacitor to the initial equivalent series resistance value, which is used to characterize the aging degree of the bus film capacitor. The arithmetic mean of a preset number of corrected estimated temperature values ​​is taken as the actual estimated temperature.

[0033] Thirdly, this application provides a vehicle that includes the temperature estimation device described in the second aspect.

[0034] Fourthly, an electronic device is provided, comprising: a processor and a memory storing at least one computer program, wherein the at least one computer program is loaded and executed by the processor to implement the temperature estimation method of the first aspect described above.

[0035] The solutions provided in the second to fourth aspects above are used to implement the method provided in the first aspect above, and their specific implementations will not be described in detail here. The technical effects corresponding to any implementation method of the solutions provided in the second to fourth aspects above can be found in the technical effects corresponding to any implementation method in the first aspect above, and will not be described in detail here.

[0036] It should be noted that any of the possible implementations of any of the above aspects can be combined, provided that the solutions do not contradict each other. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of a vehicle motor controller provided in an embodiment of this application;

[0039] Figure 2 A schematic flowchart illustrating a temperature estimation method provided in an embodiment of this application;

[0040] Figure 3 A schematic flowchart illustrating another temperature estimation method provided in an embodiment of this application;

[0041] Figure 4 This is a schematic diagram of a thin-film capacitor temperature estimation and trigger protection strategy provided in an embodiment of this application;

[0042] Figure 5 This is a schematic diagram of the structure of a temperature estimation device provided in an embodiment of this application;

[0043] Figure 6 This is a block diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0044] In the embodiments of this application, in order to clearly describe the technical solutions of the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different. The technical features described by "first" and "second" have no sequential or size order.

[0045] In the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0046] In the embodiments of this application, at least one can also be described as one or more, and multiple can be two, three, four or more, and this application does not impose any restrictions.

[0047] Furthermore, the network architecture and scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0048] To facilitate understanding, the terms used in the embodiments of this application will be explained first.

[0049] Bus film capacitors are core energy storage and filtering components used in the DC bus of motor controllers for new energy vehicles. They use thin film as the dielectric material and their main functions are to buffer the energy exchange between the DC bus and the motor, filter out high-frequency interference in the bus voltage, and stabilize the bus voltage. Their operating temperature is strongly correlated with their equivalent series resistance.

[0050] Analog-to-Digital Converter (AD Converter): A key signal conversion component in the motor controller, used to convert analog signals output from the bus voltage acquisition circuit and three-phase current sensor into digital signals so that the microcontroller unit can perform data processing such as ripple parameter calculation and equivalent series resistance derivation.

[0051] Ripple voltage: refers to the instantaneous fluctuation amplitude of the DC bus voltage on the basis of the stable DC component, mainly caused by the charging and discharging of the bus thin film capacitor and the switching of the inverter switching transistor.

[0052] Ripple current: refers to the AC current component flowing through the busbar thin film capacitor, which originates from the instantaneous changes in the motor winding current and high-frequency interference under braking and generating conditions.

[0053] Microcontroller Unit (MCU): refers to the core computing and control center of the motor controller of a new energy vehicle. It pre-stores the temperature estimation algorithm logic of this application and coordinates the work of the AD converter, memory and external interface.

[0054] Equivalent Series Resistance (ESR): refers to the parasitic resistance that exists in the actual operation of busbar film capacitors. Its resistance increases monotonically with the increase of capacitor temperature and increases with the degree of capacitor aging.

[0055] Pulse Width Modulation (PWM) commands are key control signals output by the motor controller to the inverter. By adjusting the width of the pulse signal, i.e., the ratio of the duration of the high-level to the low-level pulse, the PWM command controls the on / off state of the power switching transistors in the inverter, thereby adjusting the effective value of the output voltage and achieving precise control of operating parameters such as motor speed and torque. Specific types of PWM commands include zero-vector commands.

[0056] In existing technologies, there are four main typical solutions for monitoring the temperature of busbar thin-film capacitors: First, the thermocouple method, which requires the additional implantation of thermocouple sensors and matching signal acquisition circuits inside or on the surface of the capacitor to measure the capacitor temperature through direct contact; however, this solution not only increases the cost of hardware materials and assembly, but also damages the original sealing structure of the capacitor, leading to a decrease in the capacitor's resistance to environmental interference and thus reducing its reliability; Second, the operating condition method, which involves temperature calibration under fixed boundary conditions in a laboratory environment; however, actual vehicle use involves complex scenarios such as frequent acceleration and deceleration, braking and power generation, and high-temperature exposure, which far exceed the preset calibration range and are prone to the risk of missed over-temperature detection. Third, the thermal network model method requires constructing a heat conduction model of the capacitor and surrounding components such as the motor controller housing and coolant. It also requires conducting hundreds of experiments across the entire temperature range to calibrate key parameters such as thermal resistance, thermal capacity, and heat exchange coefficient. The development cycle is extremely long and the workload is enormous. Furthermore, the accuracy of the model is easily affected by airflow, vibration, and other interferences in the actual environment, leading to increased deviations in temperature estimation. Fourth, the temperature difference method indirectly estimates the capacitor temperature based on the temperature of the motor controller cavity or the circulating temperature of the coolant through a preset temperature difference coefficient. However, the capacitor generates significant self-heating during high-frequency charging and discharging, and its temperature has a transient difference from the cavity / coolant temperature, making it impossible to capture the capacitor over-temperature state in a timely manner.

[0057] Based on this, this application provides a temperature estimation method, apparatus, vehicle, and equipment to obtain the ripple voltage and ripple current of the busbar thin-film capacitor. The ripple voltage is the instantaneous fluctuation amplitude of the DC busbar voltage, and the ripple current is the AC current component flowing through the busbar thin-film capacitor. Based on the ripple voltage and ripple current, the estimated temperature value of the busbar thin-film capacitor is determined. This method eliminates the need for additional sensor implantation, avoiding damage to the sealed structure of the busbar thin-film capacitor and reducing hardware costs. Temperature is derived through ripple parameters and ESR, and aging compensation is used to improve estimation accuracy, solving the problems of large errors and slow response in existing solutions. This method can accurately capture capacitor temperature, ensuring stable operation of the motor controller and adapting to the complex operating conditions of new energy vehicles.

[0058] The solutions provided by the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0059] The solution provided in this application can be applied to a vehicle motor controller as shown in the vehicle motor controller schematic diagram provided in the embodiments of this application, such as... Figure 1 The diagram shown is a schematic of a vehicle motor controller provided in an embodiment of this application.

[0060] For example, Figure 1 The vehicle motor controller 101 shown can be an integrated control unit of the electric drive system of a new energy vehicle, or it can be a separate control unit that is only responsible for motor drive and power generation control. The vehicle motor controller 101 can receive power commands issued by the vehicle controller, such as acceleration, braking and power generation commands, and output control signals to drive the motor to run, while monitoring the working status of the motor and core components in real time.

[0061] Optionally, the vehicle motor controller 101 integrates the bus thin-film capacitor, three-phase current sensor, and bus voltage acquisition circuit required by the present application. The bus thin-film capacitor is used to buffer and filter the energy at the DC bus end, the three-phase current sensor is used to acquire the real-time current of the motor winding, and the bus voltage acquisition circuit is used to capture the voltage fluctuation of the DC bus. The three together provide basic data for the temperature estimation of the bus thin-film capacitor. The ripple current is obtained based on the real-time current of the motor winding, the ripple voltage is obtained based on the voltage fluctuation of the DC bus, and the actual estimated temperature is obtained by calculation based on the ripple current and ripple voltage.

[0062] Optionally, the vehicle motor controller 101 also integrates a high-speed AD converter and a microcontroller unit. The high-speed AD converter can quickly complete the sampling of bus voltage and three-phase current during the zero vector period, while the microcontroller unit is used to execute core algorithm logic such as zero vector period identification, ripple parameter calculation, equivalent series resistance derivation, and hierarchical protection strategy triggering.

[0063] The vehicle motor controller 101 establishes signal and electrical connections with the vehicle controller, drive motor, power battery, and cooling system via wiring harnesses. Specifically, it exchanges power commands and status feedback with the vehicle controller; it connects to the drive motor to output three-phase AC power, and the drive motor operates or receives three-phase current when generating electricity; it connects to the power battery to realize the charging and discharging of DC power; and it connects to the cooling system to control the cooling water circulation flow rate and realize the temperature regulation of the bus thin film capacitor.

[0064] like Figure 2 As shown in the embodiments of this application, a temperature estimation method may include:

[0065] S201: Obtain the ripple voltage and ripple current of the bus thin film capacitor.

[0066] Among them, ripple voltage is the instantaneous fluctuation amplitude of DC bus voltage, and ripple current is the AC current component flowing through the bus thin film capacitor.

[0067] In some embodiments, a zero-vector time period corresponding to the bus thin film capacitor is determined. During the zero-vector time period, the bus voltage and three-phase current of the bus thin film capacitor are collected. The bus voltage refers to the voltage value of the DC bus, and the three-phase current is the current value of the U / V / W phase of the motor. The ripple voltage is calculated based on the bus voltage, and the ripple current is calculated based on the three-phase current.

[0068] The current values ​​of the U / V / W phases of a motor refer to the current values ​​flowing through the U-phase winding, V-phase winding, and W-phase winding of the motor.

[0069] The U-phase winding, V-phase winding, and W-phase winding of a motor refer to three sets of conductive coils symmetrically distributed on the stator of the drive motor with a spatial difference of 120 degrees electrical angle. They are the core components for realizing the conversion of electrical energy into mechanical energy.

[0070] The U-phase winding, V-phase winding, and W-phase winding are connected to the output terminals of the three-phase bridge arm of the motor controller inverter, respectively, and their ends are usually connected in a star configuration to form a neutral point.

[0071] Specifically, in the driving mode, three-phase alternating current is applied to the three sets of windings to generate a rotating magnetic field, which drives the motor to run. In the braking and generating mode, the stator windings of the generator cut the magnetic field lines to generate three-phase induced current, which is processed by the controller to charge the bus capacitor. At this time, the current flowing in the windings is negative.

[0072] Specifically, the three-phase current sensor integrated in the motor controller collects the current values ​​of the motor's U-phase, V-phase, and W-phase windings in real time under braking and generating conditions. At this time, the currents are all negative. At the same time, the DC bus voltage is sampled at high frequency during the predetermined zero vector period by the bus voltage acquisition circuit in the controller, ensuring that the acquired voltage data can completely capture the fluctuation characteristics of the capacitor during transient charging and discharging.

[0073] For example, the ripple voltage of the bus capacitor is calculated based on the bus voltage by selecting the highest and lowest values ​​of the bus voltage and taking the difference between the highest and lowest values ​​as the ripple voltage of the bus capacitor.

[0074] For example, within 5μs after the zero vector command takes effect, 10 bus voltage samples are collected, and then the data is calculated to select the highest value V1 and the lowest value V2. The ripple voltage ΔV = V1 - V2.

[0075] Specifically, the ripple current calculated based on the three-phase current refers to obtaining the composite current by synthesizing the three-phase current, and then performing high-pass filtering on the composite current to obtain the ripple current of the bus capacitor.

[0076] In the power generation operation, the three-phase currents Iu, Iv and Iw are all negative, so the three-phase currents are combined to obtain the composite current Isum.

[0077] Specifically, Isum = -(Iu + Iv + Iw).

[0078] Among them, the filtering process refers to performing a 10kHz high-pass filter on Isum, that is, a cutoff frequency of 10kHz, to filter out the DC component and low-frequency interference, and extract the AC ripple current Irms.

[0079] The zero-vector period refers to the period during which the bus thin-film capacitor becomes the main charging and discharging path.

[0080] Specifically, when the vehicle enters the braking and power generation mode, the motor speed is greater than or equal to 500 rpm, and the pulse width modulation drive signal is a zero vector command of 000 or 111, the zero vector time period corresponding to the bus thin film capacitor is determined.

[0081] Among them, the zero-vector instruction inverter is a drive command that makes all the switching transistors in the same on or off state, so that the output voltage vector is zero.

[0082] The zero vector command of 000 or 111 refers to the following: For the three-phase bridge arm of the inverter in the motor controller, corresponding to the U, V, and W phase windings of the motor, "000" means that the upper and lower bridge arm switches of the three-phase bridge arm are all turned off, and "111" means that the upper and lower bridge arm switches of the three-phase bridge arm are all turned on. Under both commands, the inverter output voltage vector is zero, and the motor will not generate electromagnetic torque. At this time, the bus film capacitor becomes the main path for energy exchange between the DC bus and the motor windings, and can stably collect the ripple voltage and ripple current during its charging and discharging process, providing accurate parameters for subsequent temperature estimation.

[0083] Optionally, to further ensure the validity of the sampled data during the zero-vector period, a preliminary verification can be performed on the data after collecting the bus voltage and three-phase current: if the difference between the highest and lowest values ​​of the 10 bus voltage samples is less than a preset threshold, or if the effective value of the synthesized current Isum after being filtered by a 10kHz high-pass filter is less than 5A, it is determined that the current zero-vector period is unstable, and the data calculation is abandoned. The next zero-vector period is then waited for before sampling is performed again, so as to avoid the impact of invalid data on the accuracy of subsequent temperature estimation.

[0084] S202: Determine the estimated temperature value of the bus thin film capacitor based on ripple voltage and ripple current.

[0085] Specifically, based on Ohm's law, we first substitute the ripple voltage ΔV and the effective value of the ripple current Irms into the formula:

[0086]

[0087] The equivalent series resistance (ESR) of the busbar film capacitor is calculated. Then, the ESR-temperature relationship curve of the busbar film capacitor, which is pre-stored in the motor controller, is called up. The calculated ESR value is matched and searched on the curve, and the corresponding temperature value is the estimated temperature value of the busbar film capacitor.

[0088] The ESR-temperature relationship curve refers to the curve showing the corresponding change between the equivalent series resistance of the busbar film capacitor and its operating temperature.

[0089] Optionally, the ESR-temperature relationship curve can be the factory technical parameter curve provided by the capacitor manufacturer, or it can be generated by measuring the ESR value corresponding to different temperature points and fitting the curve after testing the capacitor in a laboratory environment with a full temperature range of -40℃ to 125℃.

[0090] Optionally, the curve features a monotonically increasing ESR value as the temperature rises, which is pre-stored in the motor controller's memory as the core basis for inferring the capacitor temperature based on the real-time calculated ESR value.

[0091] For example, if the ripple voltage ΔV = 0.8V and the effective value of the ripple current Irms = 40A, substituting into the formula yields ESR = 0.02Ω; assuming that in the pre-stored ESR-temperature curve, the temperature corresponding to ESR = 0.02Ω is 65℃, then the estimated temperature value of the bus film capacitor at this time is 65℃.

[0092] Figure 3 This is a schematic flowchart illustrating another temperature estimation method provided in an embodiment of this application. This method can be executed by a vehicle infotainment controller, which can be... Figure 1 The vehicle motor controller 101 in the middle.

[0093] S301: Obtain the ripple voltage and ripple current of the bus thin film capacitor.

[0094] For a description of this step, please refer to S201. It will not be elaborated further here.

[0095] S302: Determine the estimated temperature value of the bus thin film capacitor based on ripple voltage and ripple current.

[0096] For a description of this step, please refer to S202; it will not be elaborated upon here.

[0097] S303: Perform compensation calculations on the estimated temperature value to obtain the actual estimated temperature value.

[0098] In some embodiments, the estimated temperature value is compensated based on the aging compensation coefficient to obtain the actual estimated temperature value.

[0099] Specifically, the estimated temperature value is corrected based on the aging compensation coefficient.

[0100] The aging compensation coefficient is the ratio of the current equivalent series resistance value of the busbar film capacitor to the initial equivalent series resistance value, and is used to characterize the aging degree of the busbar film capacitor.

[0101] Specifically, the aging compensation factor K is calculated as follows: the initial aging factor K1 is determined based on the initial equivalent series resistance value of the capacitor at the time of manufacture and the real-time equivalent series resistance value.

[0102]

[0103] Among them, ESR current ESR is the equivalent series resistance of the bus thin-film capacitor calculated in real time. initial This is the initial equivalent series resistance value of the capacitor at the factory, which is usually the calibration value under standard conditions at 25℃ and is pre-stored in the motor controller;

[0104] By combining the cumulative operating time t of the capacitor with the duration of high temperature t1, the initial aging coefficient K1 is corrected to obtain the final compensation coefficient:

[0105]

[0106] Where t0 is the capacitor's design life, usually taken as 8000 hours, a pre-stored parameter; α1 is the cumulative working time influence weighting coefficient, which is calibrated by the capacitor manufacturer through accelerated aging tests, usually in the range of 0.05-0.1, reflecting the linear correlation strength of the capacitor's aging degree as the working time of the capacitor increases under normal operating conditions; α2 is the high temperature duration influence weighting coefficient, which is also calibrated by the manufacturer through accelerated aging tests. Because high temperature significantly accelerates the aging of the capacitor dielectric, it has a stronger influence than the normal time factor, so its value is greater than 0.08.

[0107] The above correction, by superimposing the aging effects of time and high temperature, enables the subsequently calculated aging compensation coefficient K to accurately match the actual aging state of the capacitor under different usage durations and temperature environments.

[0108] After quantifying the degree of capacitor aging using the K value, the estimated temperature value is corrected using the following formula:

[0109] Actual estimated temperature value = estimated temperature value × K;

[0110] For example, the arithmetic mean of a preset number of corrected estimated temperature values ​​is taken as the actual estimated temperature.

[0111] Specifically, the preset number can be set to 5 times, or dynamically adjusted according to the stability of the operating conditions. Steps S201-S202 and aging compensation calculations are performed in 5 consecutive zero-vector time periods to obtain 5 corrected estimated temperature values ​​T1, T2, T3, T4, and T5. Then, the arithmetic mean is calculated, for example:

[0112]

[0113] Use Tactual as the final estimated temperature value.

[0114] S304: Based on the actual estimated temperature value of the busbar film capacitor, classify the protection of the busbar film capacitor.

[0115] In some embodiments, the busbar thin-film capacitors are subjected to graded protection based on a graded protection strategy.

[0116] The graded protection strategy is based on the actual estimated temperature value of the busbar film capacitor, combined with the capacitor's tolerance limit, cooling system capacity, and vehicle power requirements. It presets multiple temperature thresholds and implements cooling control and power adjustment measures of different intensities accordingly. This is a systematic protection scheme that ensures capacitor safety while maintaining the basic driving functions of the vehicle to the greatest extent. It includes Level 1 protection, Level 2 protection, and Level 3 protection.

[0117] For example, Tc represents the actual estimated temperature. Level 1 protection means that when the temperature is 90℃≤Tc<100℃, the circulation flow rate and heat dissipation intensity of the cooling water are increased to reduce the temperature of the thin film capacitor, and the protection is released when the temperature of the thin film capacitor Tc<80℃.

[0118] Level 2 protection means that when the temperature is 100℃≤Tc<105℃, the circulation flow rate and heat dissipation intensity of the coolant are turned up to the maximum, the power of the whole vehicle is limited to 70%, and the power system temperature is too high. When the film capacitor temperature Tc<90℃, it will return to Level 1 protection.

[0119] Level 3 protection: When the temperature Tc≥105℃, the cooling water circulation flow rate and heat dissipation intensity are continuously turned up to the maximum, the vehicle power is limited to 30%, indicating that the power system temperature has reached the critical value and needs to be cooled down immediately, and it will return to Level 2 protection when the film capacitor temperature Tc<95℃.

[0120] The temperature thresholds of 80℃, 90℃, 100℃, and 105℃ in the above-mentioned technical means are determined by comprehensively considering the characteristics of the busbar thin film capacitor, the cooling system capacity, and the vehicle's safety redundancy requirements.

[0121] Specifically, 105℃ is based on the maximum temperature resistance of 125℃ for commonly used film capacitors, with a safety margin of ≥20℃. 105℃ is close to the long-term tolerance temperature limit of the capacitor, requiring the activation of the most stringent power limit; 80℃ is the upper limit of the capacitor's normal safe operating temperature, serving as a primary protection release point to avoid frequent triggering; 90℃ is the critical value for effective temperature control through enhanced heat dissipation of the cooling system; and 100℃ is the trigger point for the cooling system to operate at full load.

[0122] Figure 4 This is a schematic diagram illustrating a thin-film capacitor temperature estimation and trigger protection strategy provided in an embodiment of this application. This method can be executed by a vehicle motor controller, which can be... Figure 1 The specific steps for the vehicle motor controller 101 are as follows:

[0123] S401: Real-time monitoring of motor status: torque, speed, PWM commands.

[0124] Among them, motor status refers to the set of parameters related to the current operating condition of the motor, specifically including: the real-time output torque of the motor, the actual speed of the motor rotor, and the PWM commands output by the motor controller to the inverter.

[0125] Real-time output torque of the motor: positive torque corresponds to driving conditions, and negative torque corresponds to braking and power generation conditions.

[0126] S402: Determine if the following conditions are met simultaneously: negative torque, speed not less than 500 rpm, and zero vector command.

[0127] The system determines whether the following conditions are met simultaneously based on the motor status: negative torque, speed not less than 500 rpm, and zero vector command. If so, S401 is executed.

[0128] Specifically, the signal acquisition module within the motor controller acquires and determines the following: 1. The torque signal is obtained from the torque sensor or by parsing commands issued by the vehicle controller. If the value is ≤0, the torque is considered negative. 2. The speed signal is acquired by the speed sensor and converted into a digital quantity. This digital quantity is compared with a preset 500rpm threshold. If the speed is ≥500rpm, the condition is met. 3. The PWM command signal output by the MCU is parsed to determine if it is of type 000 or 111. If so, it is considered a zero-vector command. All three conditions must be met simultaneously.

[0129] If both conditions are met, execute S403.

[0130] S403: Start the AD converter to synchronously acquire the bus voltage and three-phase current.

[0131] Optionally, when starting the AD converter, high-frequency synchronous sampling is performed according to preset parameters: the bus voltage sampling frequency is set to 2MHz, and it is continuously sampled 10 times in the zero vector period, with a sampling duration of less than or equal to 5μs; the three-phase current is synchronously collected through the three-phase current sensor, and the number of samplings is consistent with the bus voltage, ensuring that the timestamps of the voltage and current data are aligned, providing a synchronous data basis for subsequent calculations.

[0132] S404: Calculate ripple voltage and ripple current.

[0133] S405: Calculate the equivalent series resistance.

[0134] S406: Find the temperature value corresponding to the equivalent series resistance from the equivalent series resistance-temperature relationship curve to obtain the estimated temperature value.

[0135] S407: The estimated temperature value is compensated based on the aging compensation coefficient to obtain the actual estimated temperature value Tc.

[0136] S408: Determine if Tc is less than 95℃.

[0137] If Tc is less than 95℃, execute S401; if Tc is greater than or equal to 95℃, execute S409.

[0138] S409: Determine whether Tc is greater than or equal to 90℃ and less than 100℃.

[0139] If Tc is greater than or equal to 90℃ and less than 100℃, then execute S410; if Tc is not greater than or equal to 90℃ and less than 100℃, then execute S411.

[0140] S410: Activate Level 1 protection until Tc is less than 80℃, then deactivate protection.

[0141] For example, the specific measures for Level 1 protection are as follows: The motor controller sends a command to the electronic water pump of the cooling system to increase the water pump speed from the base speed to 70% of the rated speed, and at the same time, the cooling fan is turned on to run at medium speed to enhance heat dissipation; Tc is refreshed every 100ms. If Tc < 80℃ is detected for 3 consecutive times, a reset signal is sent to the cooling system to restore the water pump and fan to the basic working state and deactivate Level 1 protection.

[0142] S411: Determine whether Tc is greater than or equal to 100℃ and less than 105℃.

[0143] If Tc is greater than or equal to 100℃ and less than 105℃, then execute S412; if Tc is not greater than or equal to 100℃ and less than 105℃, then execute S413.

[0144] S412: Activate Level 2 protection until Tc is less than 90℃, then revert to Level 1 protection.

[0145] For example, the specific measures for Level 2 protection are as follows: the cooling system operates at full load, the water pump speed is increased to 100% of the rated speed, and the cooling fan starts running at high speed; the motor controller sends a torque limit request to the vehicle controller to limit the maximum output torque of the motor to 70% of the rated torque; a command is sent to the instrument panel via the bus to illuminate the yellow temperature alarm light and display a text message indicating that the power system temperature is too high and to slow down; 4. Real-time monitoring of Tc; if Tc < 90℃ is detected 5 times consecutively, the system switches to Level 1 protection.

[0146] S413: Determine whether Tc is greater than or equal to 105℃.

[0147] If Tc is greater than or equal to 105℃, then execute S414.

[0148] S414: Activate Level 3 protection until Tc is less than 95℃, then revert to Level 2 protection.

[0149] For example, Level 3 protection means that the cooling system maintains full-load operation; the motor controller limits the maximum output torque of the motor to 30% of the rated torque; the instrument panel triggers a red warning light to flash and a buzzer to indicate that the power system temperature is critical, requiring immediate shutdown to cool down and reporting a fault code; if Tc is still not <95℃ within 10 minutes after triggering, the vehicle speed is limited to ≤20km / h; when Tc <95℃ is detected 8 times consecutively, the system switches to Level 2 protection.

[0150] This application provides a schematic diagram of the structure of a temperature estimation device, as shown in the embodiment. Figure 5 As shown, the temperature estimation device may include: an acquisition module 501 and an analysis module 502.

[0151] The acquisition module 501 is used to execute Figure 2 The operation of S201 in the illustrated method and Figure 3 The illustrated method involves the operation of S301; the analysis module 502 is used to execute... Figure 2 Operation of S202 and Figure 3 Operation of S302.

[0152] In some embodiments, the temperature estimation device includes hardware structures and / or software modules corresponding to the execution of each function in order to achieve the above-described functions. Those skilled in the art will readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0153] This application embodiment can divide the temperature estimation device into functional modules according to the above method embodiment. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0154] Figure 6 This is a block diagram of an electronic device provided in an embodiment of this application. (For example...) Figure 6 As shown, the electronic device includes, but is not limited to, a processor 601 and a memory 602.

[0155] The memory 602 described above is used to store the executable instructions of the processor 601. It is understood that the processor 601 is configured to execute instructions to implement the testing method in the above embodiments.

[0156] It should be noted that those skilled in the art will understand that Figure 6 The electronic device structure shown does not constitute a limitation on the electronic device; the electronic device may include, but is not limited to, other electronic devices. Figure 6 This may indicate more or fewer components, or combinations of certain components, or different component arrangements.

[0157] Processor 601 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in memory 602, and by calling data stored in memory 602, it performs various functions and processes data, thereby providing overall monitoring of the electronic device. Processor 601 may include one or more processing units. Optionally, processor 601 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into processor 601.

[0158] The memory 602 can be used to store software programs and various data. The memory 602 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as a determination unit, processing unit, etc.), etc. Furthermore, the memory 602 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0159] Through the above description of the implementation methods, those skilled in the art will clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the module can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, modules, and units described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0160] The method steps in this embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary embodiment couples a storage medium to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Additionally, the ASIC can reside in a network device. Alternatively, the processor and storage medium can exist as discrete components in the network device. In the above embodiments, implementation can be entirely or partially achieved through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented entirely or partially as a computer program product. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded and executed on a computer, all or part of the processes or functions of the embodiments of this application are performed. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable module. The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, a computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; or an optical medium, such as a digital video disc (DVD); or a semiconductor medium, such as a solid-state drive (SSD). The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0161] Since the temperature estimation device in the embodiments of the present invention can be applied to the above-described method, the technical effects it can achieve can also be referred to the above-described method embodiments, and the embodiments of the present invention will not be repeated here. The above are only specific embodiments of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims. The method steps in this embodiment can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, thereby enabling the processor to read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a network device. Of course, the processor and storage medium can also exist as discrete components in the network device. In the above embodiments, implementation can be entirely or partially achieved through software, hardware, firmware, or any combination thereof. When implemented in software, it can be entirely or partially implemented in the form of a computer program product. A computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, all or part of the processes or functions of the embodiments of this application are performed. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable modules. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, a computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media.The usable medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); or it can be a semiconductor medium, such as a solid-state drive (SSD). The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A temperature estimation method, characterized by, The method comprises: obtaining the ripple voltage and the ripple current of the bus film capacitor, the ripple voltage being the instantaneous fluctuation amplitude of the DC bus voltage, and the ripple current being the AC current component flowing through the bus film capacitor; determining the estimated temperature value of the bus film capacitor based on the ripple voltage and the ripple current.

2. The method of claim 1, wherein, The determination of the estimated temperature value of the bus film capacitor based on the ripple voltage and the ripple current comprises: calculating the equivalent series resistance value of the bus film capacitor according to the ripple voltage and the ripple current; obtaining the estimated temperature value of the bus film capacitor based on the equivalent series resistance.

3. The method of claim 2, wherein, The obtaining of the estimated temperature value of the bus film capacitor based on the equivalent series resistance comprises: based on the equivalent series resistance, searching for the temperature value corresponding to the equivalent series resistance from the equivalent series resistance-temperature relationship curve corresponding to the bus film capacitor to obtain the estimated temperature value.

4. The method of claim 1, wherein, The obtaining of the ripple voltage and the ripple current of the bus film capacitor comprises: determining the zero vector period corresponding to the bus film capacitor, the zero vector period being a period in which the bus film capacitor becomes a main charging and discharging path; in the zero vector period, collecting the bus voltage and the three-phase current of the bus film capacitor, the bus voltage being the voltage value of the DC bus, and the three-phase current being the current value of the motor U / V / W phase; calculating the ripple voltage based on the bus voltage; calculating the ripple current based on the three-phase current.

5. The method of claim 4, wherein, The determination of the zero vector period corresponding to the bus film capacitor comprises: in the case that the whole vehicle enters the braking and power generation working condition, the motor speed is greater than or equal to 500 rpm, and the zero vector instruction of the pulse width modulation driving signal is 000 or 111, determining the zero vector period corresponding to the bus film capacitor, the zero vector instruction being a driving instruction in which all the switching tubes of the inverter are in the same conduction or off state, so that the output voltage vector is zero.

6. The method according to any one of claims 1 to 5, characterized in that, The method further comprises: performing compensation calculation on the estimated temperature value to obtain an actual estimated temperature value.

7. The method of claim 6, wherein, The compensation calculation on the estimated temperature value to obtain the actual estimated temperature value comprises: performing compensation calculation on the estimated temperature value based on an aging compensation coefficient to obtain the actual estimated temperature value.

8. The method of claim 7, wherein, The compensation calculation on the estimated temperature value based on the aging compensation coefficient to obtain the actual estimated temperature value comprises: modifying the estimated temperature value based on an aging compensation coefficient, the aging compensation coefficient being the ratio of the current equivalent series resistance value of the bus film capacitor to the initial equivalent series resistance value, and being used to represent the aging degree of the bus film capacitor; taking the arithmetic mean of a preset number of the modified estimated temperature values as the actual estimated temperature.

9. The method of claim 1, wherein, The method further comprises: based on the actual estimated temperature value of the bus film capacitor, performing graded protection on the bus film capacitor.

10. A temperature estimation device, characterized by comprising: The device comprises: an obtaining module: configured to obtain the ripple voltage and the ripple current of the bus film capacitor, the ripple voltage being the instantaneous fluctuation amplitude of the DC bus voltage, and the ripple current being the AC current component flowing through the bus film capacitor; an analysis module configured to determine an estimated temperature value of the busbar film capacitor based on the ripple voltage and the ripple current.

11. A vehicle characterized by comprising: The temperature estimation of the busbar film capacitor in the vehicle is applied by the method according to any one of claims 1-9.

12. An electronic device, comprising: comprising: a processor; a memory storing a computer program; when the computer program is executed by the processor, the method according to any one of claims 1-9 is implemented.

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