Control method, device and equipment of electric drive system of vehicle

Abstract

The application discloses a control method, device and equipment of an electric drive system of a vehicle, and the method comprises the following steps: acquiring the current lubricating oil temperature of the electric drive system of the vehicle; if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold, acquiring at least one operating parameter of the vehicle; and if the at least one operating parameter is within a preset parameter range, performing start-stop alternating control on the oil pump of the electric drive system. The application solves the technical problem of low efficiency of the electric drive system.

Description

Technical Field

[0001] This invention belongs to the field of vehicle control technology, and particularly relates to a control method, device and equipment for an electric drive system of a vehicle. Background Technology

[0002] With the rapid development of electric vehicles, the low-temperature range issue exposed by electric vehicles has attracted increasing attention. In addition to a significant decrease in battery power output and increased energy consumption due to other thermal management requirements in low-temperature environments, the efficiency of the electric drive system also decreases significantly. The low-temperature efficiency loss of the electric drive system mainly consists of losses in three major components: the motor, the electronic control system, and the reducer. Among these, reducer losses account for a large portion of the electric drive efficiency loss at low temperatures, especially in the early stages of low-temperature operation.

[0003] A significant reason for the efficiency loss in the speed reducer is that during the initial stages of vehicle operation, the low temperature of the lubricating oil inside the reducer leads to high viscosity and poor fluidity. This makes it difficult for the lubricating oil to form an effective oil film between the gears, increasing friction and reducing reducer efficiency. Low reducer efficiency, in turn, results in low efficiency in the electric drive system, increasing energy loss and reducing user experience. Therefore, the low efficiency of the electric drive system is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This invention provides a control method, apparatus, and device for a vehicle's electric drive system, solving the technical problem of low efficiency in electric drive systems.

[0005] In a first aspect, embodiments of the present invention provide a control method for an electric drive system of a vehicle, comprising: acquiring the current lubricating oil temperature of the electric drive system of the vehicle; if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold, acquiring at least one operating parameter of the vehicle; if the at least one operating parameter is within a preset parameter range, performing start-stop alternating control on the oil pump of the electric drive system.

[0006] In conjunction with the first aspect of the present invention, in some embodiments, obtaining the current lubricating oil temperature of the vehicle's electric drive system includes: obtaining the current motor temperature of the electric drive system; inputting the current motor temperature into a preset first correspondence relationship to obtain the current lubricating oil temperature of the electric drive system, wherein the first correspondence relationship is a correspondence between motor temperature and lubricating oil temperature.

[0007] In conjunction with the first aspect of the present invention, in some embodiments, the alternating start-stop control of the oil pump of the electric drive system includes: if the current lubricating oil temperature of the electric drive system is less than the preset temperature threshold, alternating start-stop control of the oil pump of the electric drive system based on a first start duration and a first stop duration; if the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold, maintaining the oil pump in the start state.

[0008] In conjunction with the first aspect of the present invention, in some embodiments, the first start-up duration is the lubrication duration required for the bearing of the electric drive system to switch from a severely under-lubricated state to a fully lubricated state. The severely under-lubricated state is the bearing state corresponding to the deviation between the amount of lubricating oil in the bearing of the electric drive system and a first preset oil amount being less than a preset first oil amount deviation threshold. The fully lubricated state is the bearing state corresponding to the deviation between the amount of lubricating oil in the bearing of the electric drive system and a second preset oil amount being less than a preset second oil amount deviation threshold, wherein the second preset oil amount is greater than the first preset oil amount. The first stop duration is the sum of a first sub-duration and a second sub-duration, wherein the first sub-duration is the duration during which the bearing of the electric drive system can operate smoothly in the severely under-lubricated state, and the second sub-duration is the duration during which the amount of lubricating oil in the bearing of the electric drive system decreases from the second preset oil amount to the first preset oil amount when the oil pump of the electric drive system is in a stopped state.

[0009] In conjunction with the first aspect of the present invention, in some embodiments, the alternating start-stop control of the oil pump of the electric drive system based on a first start duration and a first stop duration includes: controlling the oil pump of the electric drive system to start running for the first start duration, controlling the oil pump of the electric drive system to stop for the first stop duration, and then controlling the oil pump of the electric drive system to restart.

[0010] In conjunction with the first aspect of the present invention, in some embodiments, the alternating start-stop control of the oil pump of the electric drive system based on a first start-up duration and a first stop duration includes: obtaining the target lubricating oil temperature required by the reducer of the electric drive system during the current start-stop cycle; modifying the first start-up duration and the first stop duration based on the target lubricating oil temperature and the current lubricating oil temperature to obtain a second start-up duration and a second stop duration, wherein the second stop duration is less than or equal to the first stop duration; and performing a start-stop control on the oil pump once during the current start-stop cycle based on the second start-up duration and the second stop duration, so that the lubricating oil temperature of the electric drive system rises from the current lubricating oil temperature to the target lubricating oil temperature.

[0011] In conjunction with the first aspect of the present invention, in some embodiments, the at least one operating parameter includes the motor torque and motor speed of the electric drive system, and the method further includes: if the motor torque of the electric drive system is within a preset first torque range and the motor speed of the electric drive system is within a preset first speed range, determining that the at least one operating parameter is within the preset parameter range.

[0012] In conjunction with the first aspect of the present invention, in some embodiments, the first torque range and the first speed range are obtained in advance through the following steps: acquiring operating data obtained from testing the vehicle, the operating data including multiple operating sub-data, each of the operating sub-data including operating information and the duration ratio corresponding to the operating information, the operating information including the motor torque range and motor speed range of the electric drive system; determining a second torque range and a second speed range based on the operating data; acquiring a first degree of damage to the bearing of the electric drive system when it is in the extreme lean oil state within the second torque range and the second speed range; and determining the first torque range and the first speed range based on the first degree of damage, a preset damage degree threshold, the second torque range, and the second speed range.

[0013] Secondly, embodiments of the present invention provide a control device for an electric drive system of a vehicle, comprising: a temperature acquisition unit for acquiring the current lubricating oil temperature of the electric drive system of the vehicle; a parameter acquisition unit for acquiring at least one operating parameter of the vehicle if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold; and a start-stop control unit for performing start-stop alternating control on the oil pump of the electric drive system if the at least one operating parameter is within a preset parameter range.

[0014] Thirdly, embodiments of the present invention provide an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method described in any of the first aspects.

[0015] The one or more technical solutions provided in the embodiments of the present invention achieve at least the following technical effects or advantages:

[0016] This invention, in its embodiments, acquires the current lubricating oil temperature of the vehicle's electric drive system. If the current lubricating oil temperature is lower than a preset temperature threshold, it acquires at least one operating parameter of the vehicle. If at least one operating parameter is within a preset parameter range, it performs alternating start-stop control on the oil pump of the electric drive system. When the oil pump is running, it pumps out some lubricating oil from inside the reducer, reducing the amount of oil churning inside the reducer. When the oil pump is stopped, the lubricating oil flows back into the reducer, increasing the amount of oil churning inside the reducer. Therefore, by alternating start-stop control of the oil pump, it prevents the pump from being continuously running, thereby increasing the amount of oil churning inside the reducer. This accelerates the temperature rise of the lubricating oil in the electric drive system, reducing the viscosity of the lubricating oil and forming an effective oil film between the gears of the reducer, reducing friction and improving the reducer efficiency. Thus, the efficiency of the electric drive system is improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the control method for the electric drive system of a vehicle in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the oil pump operation stage in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of vehicle speed changes under CLTC conditions in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the motor torque under CLTC operating conditions in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the motor speed under CLTC operating conditions in an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the discretized point diagram of motor torque under CLTC operating condition in an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of the discretized point diagram of motor speed under CLTC operating condition in an embodiment of the present invention;

[0025] Figure 8 This is a schematic diagram of a second correspondence in an embodiment of the present invention;

[0026] Figure 9 This is a functional block diagram of the control device of the electric drive system of a vehicle in an embodiment of the present invention;

[0027] Figure 10 This is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] In this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0030] This invention provides a control method for a vehicle's electric drive system, with reference to... Figure 1 As shown, the method includes the following steps S101 to S103:

[0031] S101: Obtain the current lubricating oil temperature of the vehicle's electric drive system.

[0032] It should be noted that the vehicle's electric drive system mainly includes a drive motor, a motor controller, and a transmission mechanism. The electric drive system is responsible for converting the electrical energy of the battery pack into mechanical energy to drive the vehicle.

[0033] In some implementations, obtaining the current lubricating oil temperature of the vehicle's electric drive system may include: obtaining the current motor temperature of the electric drive system; inputting the current motor temperature into a preset first correspondence relationship to obtain the current lubricating oil temperature of the electric drive system, wherein the first correspondence relationship is the correspondence between the motor temperature and the lubricating oil temperature.

[0034] In some implementations, a resistance temperature sensor is installed on the motor of the electric drive system to obtain the current motor temperature of the electric drive system. This can include obtaining the current motor temperature of the electric drive system through the resistance temperature sensor. The resistance temperature sensor can be an NTC temperature sensor.

[0035] It should be noted that the mathematical relationship between the reducer lubricating oil temperature and the motor NTC temperature can be confirmed through experiments or simulations. The motor NTC temperature can be used to match the initial and target lubricating oil temperatures of the reducer. Furthermore, by obtaining the current motor temperature using a resistance temperature sensor on the motor, and then determining the lubricating oil temperature based on this current motor temperature, the need for additional sensors to detect the lubricating oil temperature is avoided, reducing reliance on hardware.

[0036] S102: If the current lubricating oil temperature of the electric drive system is lower than the preset temperature threshold, obtain at least one operating parameter of the vehicle.

[0037] It should be noted that the preset temperature threshold can be a temperature less than 90℃, such as 30℃, 20℃, 10℃, and -10℃, etc.

[0038] S103: If at least one operating parameter is within the preset parameter range, the oil pump of the electric drive system is controlled to start and stop alternately.

[0039] It should be noted that at least one operating parameter is within a preset parameter range, which can be a characteristic that the bearing load of the electric drive system is less than a preset load threshold. At least one operating parameter may include the motor torque and / or motor speed of the electric drive system.

[0040] In some implementations, alternating start-stop control of the oil pump in the electric drive system may include: if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold, alternating start-stop control of the oil pump in the electric drive system based on a first start duration and a first stop duration; if the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold, maintaining the oil pump in the start state.

[0041] In some embodiments, the first start-up duration is the lubrication time required for the bearing of the electric drive system to switch from a severely lean state to a fully lubricated state. The severely lean state is the bearing state corresponding to the deviation between the amount of lubricating oil in the bearing of the electric drive system and a first preset oil amount is less than a preset first oil amount deviation threshold. The fully lubricated state is the bearing state corresponding to the deviation between the amount of lubricating oil in the bearing of the electric drive system and a second preset oil amount is less than a preset second oil amount deviation threshold. The second preset oil amount is greater than the first preset oil amount. The first stop duration is the sum of the first sub-duration and the second sub-duration. The first sub-duration is the duration during which the bearing of the electric drive system can operate smoothly in the severely lean state. The second sub-duration is the duration during which the amount of lubricating oil in the bearing of the electric drive system decreases from the second preset oil amount to the first preset oil amount when the oil pump of the electric drive system is stopped.

[0042] It should be noted that while increasing the stop time during start-up and shutdown can increase the amount of oil churning in the reducer and thus rapidly raise the oil temperature, the stop time cannot be increased indefinitely. This is because when the oil pump is stopped, lubricating oil flows back to the reducer, reducing the amount of lubricating oil in the bearings of the electric drive system and increasing the risk of bearing damage. If the lubricating oil level drops below a certain threshold, the safe operation of the bearings may be compromised. Therefore, this embodiment of the invention determines the start-up and stop times based on the bearing's extreme lean-oil state and fully lubricated state, avoiding excessive oil pump stop time that could damage the bearings. This achieves a balance between accelerating the lubricating oil temperature rise and ensuring the safety of the electric drive system.

[0043] refer to Figure 2 As shown, Figure 2 This is a schematic diagram of the oil pump operation stage in an embodiment of the present invention. l0 can be a first preset oil quantity, l1 can be a second preset oil quantity, t0 is a first sub-duration, t1 is a first start-up duration, and t2 is a second sub-duration. The above times and lubricating oil quantities can be confirmed by simulation calculations or individual tests by the bearing supplier.

[0044] In some implementations, the alternating start-stop control of the oil pump of the electric drive system based on a first start duration and a first stop duration may include: controlling the oil pump of the electric drive system to start running for a first start duration, then controlling the oil pump of the electric drive system to stop for a first stop duration, and then controlling the oil pump of the electric drive system to restart.

[0045] In other embodiments, the start-stop alternating control of the oil pump of the electric drive system based on the first start-up duration and the first stop duration may include the following steps S1031 to S1033:

[0046] S1031: Obtain the target lubricating oil temperature required by the reducer of the electric drive system during the current start-stop cycle.

[0047] In some implementations, step S1031 may be: obtaining the target efficiency increment of the reducer in the current start-stop cycle; determining the target lubricating oil temperature based on a preset second correspondence, the target efficiency increment and the current lubricating oil temperature of the electric drive system, wherein the second correspondence is the correspondence between the efficiency of the reducer and the lubricating oil temperature.

[0048] In some implementations, determining the target lubricating oil temperature based on a preset second correspondence, the target efficiency increment, and the current lubricating oil temperature of the electric drive system may include: inputting the current lubricating oil temperature of the electric drive system into the second correspondence to obtain the current efficiency of the reducer; determining the target efficiency of the reducer based on the current efficiency of the reducer and the target efficiency increment; and inputting the target efficiency of the reducer into the second correspondence to obtain the target lubricating oil temperature.

[0049] S1032: Based on the target lubricating oil temperature and the current lubricating oil temperature, the first start-up duration and the first stop duration are corrected to obtain the second start-up duration and the second stop duration, wherein the second stop duration is less than or equal to the first stop duration.

[0050] Specifically, referring to the following formulas (1) to (4), the correction process can refer to the following steps 1 to 3: Step 1, obtain relevant parameters in advance. Specifically, under the working condition where at least one operating parameter is within the preset parameter range, assume that l2 is the amount of oil churning in the reducer when the oil pump is started at this working condition, l3 is the amount of oil churning in the reducer when the oil pump is not started at this working condition, and P0 is the power of the reducer under this working condition. Through simulation or experiment, determine the reducer efficiency η1 and η2 corresponding to the amount of oil churning in l2 and l3 respectively; obtain the increase in efficiency loss caused by starting and stopping the oil pump as η2-η1. This increase in efficiency loss heats the lubricating oil in the form of heat, making the lubricating oil heat up faster, and the increased heating power can be obtained as: P0×(η2-η1). Step 2, the third start time can be greater than or equal to the first start time. Each time, select a different third start time and input it into formula (1) to obtain the corresponding third stop time. Based on the third start time and the third stop time corresponding to the third start time, a set of start and stop times can be obtained. By repeatedly selecting different third start-up durations and inputting them into equation (1), multiple sets of start-up and stop durations can be obtained. Step 3: According to equation (4), for each set of start-up and stop durations in the multiple sets of start-up and stop durations, substituting it into equation (4) will yield a ratio value. The set of start-up and stop durations corresponding to the largest ratio value is taken as the target set of start-up and stop durations. The third start-up duration of the target set of start-up and stop durations is taken as the second start-up duration. The minimum value between the third stop duration of the target set of start-up and stop durations and the first stop duration is taken as the second stop duration.

[0051] ρ×l3×c×(T1-T0)=(P0×η1×t3)+(P0×η2×t4) (1);

[0052] Q = m × c × (T1 - T0) (2);

[0053] m=ρ×v (3);

[0054]

[0055] Where m is the weight of lubricating oil, Q is the heat of lubricating oil heating, c is the specific heat capacity of lubricating oil, ρ is the density of lubricating oil, v is the volume of lubricating oil, T0 is the current lubricating oil temperature, T1 is the target lubricating oil temperature, l3 is the amount of oil churning in the reducer when the oil pump is not running at this operating point, η1 is the reducer efficiency when the reducer oil churning amount is l2, η2 is the reducer efficiency when the reducer oil churning amount is l3, l2 is the amount of oil churning in the reducer when the oil pump is running at this operating point, t3 is the third start-up time, t4 is the third stop time, and P0 is the reducer power under this operating condition.

[0056] S1033: During the current start-stop cycle, the oil pump is controlled to start and stop once based on the second start duration and the second stop duration, so that the lubricating oil temperature of the electric drive system rises from the current lubricating oil temperature to the target lubricating oil temperature.

[0057] In some implementations, controlling the oil pump to start and stop based on the second start duration and the second stop duration can be: controlling the oil pump of the electric drive system to start running for the second start duration, and then controlling the oil pump of the electric drive system to stop for the second stop duration.

[0058] It should be noted that while a longer oil pump stop time leads to a faster lubricating oil temperature rise and a greater increase in reducer efficiency, it also increases the damage to the bearings of the electric drive system. Therefore, a longer oil pump stop time is not always better. This embodiment of the invention determines the target lubricating oil temperature based on the target efficiency increment of the reducer, thereby adjusting the oil pump stop time. This not only improves reducer efficiency and achieves the beneficial effect of accurate reducer efficiency control, but also reduces the degree of bearing damage in the electric drive system. Therefore, it achieves the beneficial effect of balancing improved reducer efficiency with reduced bearing damage in the electric drive system.

[0059] In some implementations, at least one operating parameter includes the motor torque and motor speed of the electric drive system. In this case, the control method of the electric drive system of the vehicle may further include: if the motor torque of the electric drive system is within a preset first torque range and the motor speed of the electric drive system is within a preset first speed range, determining that at least one operating parameter is within a preset parameter range.

[0060] In some implementations, the first torque range and the first speed range are obtained in advance through the following steps, including steps A through D:

[0061] Step A: Obtain the operational data obtained from testing the vehicle. The operational data includes multiple operational sub-data points. Each operational sub-data point includes operational information and the corresponding duration ratio. The operational information includes the motor torque range and motor speed range of the electric drive system.

[0062] Step B: Based on the operating data, determine the second torque range and the second speed range.

[0063] In some implementations, step B may include: selecting a portion of the running sub-data from multiple running sub-data, wherein the deviation of the sum of the duration proportions of each running sub-data in the portion of the running sub-data from a preset duration proportion is less than a preset proportion deviation threshold; performing a union operation on the motor torque ranges of each running sub-data in the portion of the running sub-data to obtain a second torque range, wherein the deviation of the lower limit of the second torque range from zero is less than a preset torque deviation threshold, and the torque values ​​of the second torque range are continuous; and performing a union operation on the motor speed ranges of each running sub-data in the portion of the running sub-data to obtain a second speed range, wherein the deviation of the lower limit of the second speed range from zero is less than a preset speed deviation threshold, and the speed values ​​of the second speed range are continuous.

[0064] It should be noted that the lower limit of the second torque range can be zero, and the lower limit of the second speed range can also be zero. The following explains the continuous characteristic. For example, torque range a includes values ​​of (10, 20) ∪ (30, 40], torque range b includes values ​​of (10, 30), speed range c includes values ​​of (1000, 2000) ∪ (3000, 4000], and speed range d includes values ​​of (1000, 3000). Then, the torque values ​​of torque range a are discrete, the torque values ​​of torque range b are continuous, the speed values ​​of speed range c are discrete, and the speed values ​​of speed range d are continuous.

[0065] Step C: Within the second torque range and the second speed range, obtain the first degree of damage when the bearing of the electric drive system is in an extreme lean-oil state.

[0066] It should be noted that the first degree of damage can be obtained from a preset correspondence, which can be a correspondence between torque range, speed range and degree of damage.

[0067] Step D: Based on the first degree of damage, the preset damage degree threshold, the second torque range, and the second speed range, determine the first torque range and the first speed range.

[0068] In some implementations, step D may include: if the first degree of damage is greater than a preset damage degree threshold, reducing the upper limit of the second torque range to obtain the first torque range, and reducing the upper limit of the second speed range to obtain the first speed range; wherein, under the first torque range and the first speed range, the second degree of damage of the bearing of the electric drive system in the extreme lean oil state is less than or equal to the preset damage degree threshold; if the first degree of damage is less than or equal to the preset damage degree threshold, the second torque range is used as the first torque range, and the second speed range is used as the first speed range.

[0069] It should be noted that, in the process of determining the first torque range and the first speed range based on the degree of damage, the total running time of the optimized area operating point can be determined based on the customer operating conditions throughout the entire life cycle of the vehicle. The bearing damage c% in the optimized area under the original lubrication condition is calculated, the bearing damage d% under the extreme lean oil condition is calculated, and the bearing damage e% under the durability load spectrum throughout the entire life cycle is calculated. If the bearing damage (e-c+d)% under the extreme lean oil condition in the optimized area exceeds the bearing design life, then the optimization range is narrowed, and the final optimization range is obtained by combining the intersection of the previously confirmed optimization areas.

[0070] It should be noted that the oil pump of the electric drive system is controlled to alternately start and stop only within the first torque range and the first speed range. However, this alternating start and stop control can damage the bearings of the electric drive system. If the damage is too severe, it will reduce the operational safety of the electric drive system. Therefore, this embodiment of the invention limits the determination of the first torque range and the first speed range based on a first damage level, a preset damage level threshold, a second torque range, and a second speed range. This avoids the damage level exceeding the preset damage level threshold, ensuring the safe operation of the bearings and thus guaranteeing the operational safety of the electric drive system.

[0071] It should be noted that the specific application scenario of this invention embodiment can be the initial driving stage of a vehicle. In this stage, the current lubricating oil temperature of the electric drive system is lower than a preset temperature threshold, the vehicle speed is lower than a preset speed threshold, and the throttle opening is lower than a preset opening threshold; that is, a low-temperature, low-speed, and low-load scenario. The initial driving stage can refer to the period from the start of driving to half an hour thereafter. In this low-temperature, low-speed, and low-load scenario, the bearing load of the electric drive system is small, resulting in less damage. Therefore, the lubricating oil requirement for the bearings is low. At this time, the oil pump can be started and stopped, increasing the pump's stop time. Even if the bearing lubricating oil level is low, it will not cause excessive damage. Therefore, to accurately identify the low-temperature, low-speed, and low-load scenario, this invention embodiment can determine this through lubricating oil temperature and operating parameters. In particular, combining motor torque and motor speed for operating parameters allows for better judgment of vehicle status and accurate identification of scenarios. For example, when a vehicle is heavily loaded, with high throttle but low speed, although the motor speed is low, the torque is high, which does not fall under the low-temperature, low-speed, low-load scenario. In this case, the bearing load is high, and controlling the start-stop of the oil pump may cause significant bearing damage. Therefore, relying solely on a single operating parameter may lead to misjudgment. To improve the accuracy of vehicle status judgment, this embodiment of the invention limits the judgment to combining motor torque and motor speed, achieving the beneficial effect of improving the accuracy of vehicle status judgment. Furthermore, because the vehicle status is accurately judged, the situation of significant bearing damage caused by controlling the start-stop of the oil pump is avoided, thus ensuring the safe operation of the bearing.

[0072] It should be noted that the embodiments of the present invention can be used to optimize the low-temperature loss of oil-cooled electric drive reducers. Through optimization of the electronic oil pump control strategy, the oil pump is shut down under certain operating conditions, increasing oil agitation and simultaneously raising the motor body temperature. Intermittent oil pumping ensures basic lubrication of the motor and removes the heat generated by the motor, allowing the lubricating oil temperature to rise rapidly at low temperatures, thereby improving the efficiency of the electric drive at low temperatures. Under low-temperature, low-speed, and low-load conditions, controlling the start-stop of the oil pump allows the reducer to agitate the oil for more time while ensuring basic lubrication of the bearings and gears, thus raising the reducer lubricating oil temperature more quickly and reducing the lubricating oil viscosity. Simultaneously, due to the start-stop of the oil pump under low-temperature, low-speed, and low-load conditions, the cooling effect of the lubricating oil on the motor stator and rotor is significantly reduced, leading to an increase in the motor stator and rotor temperature and improving motor efficiency. Therefore, the low-temperature efficiency of the electric drive can be further improved. This solves the problems of low reducer efficiency and high energy consumption, greatly improving the problem of low low-temperature range in electric vehicles.

[0073] The following further explains the process of acquiring operating data: In the examples below, the unit of speed is rpm and the unit of torque is Nm. For the operating conditions requiring optimized efficiency, the torque, speed, and time point signals under the optimized operating conditions are clearly output through dynamic simulation software or actual vehicle data collection. The resulting speed and torque signals are continuous signals. Data discretization effectively reduces the data by a certain step, facilitating statistical confirmation of the number of operating point landings (running time at each speed and torque) under each speed and torque, thereby confirming the proportion of running time under each operating condition. Based on the original operating condition efficiency and the efficiency optimization target, the target to be improved is determined. Low speed and low torque are used as the optimization target of this scheme. The efficiency is improved by optimizing the efficiency in the low speed and low torque region. For non-optimized operating conditions, no oil pump strategy is implemented; the original oil pump strategy continues to be used. The process expands outward from the minimum origin point, primarily by changing the speed (i.e., prioritizing the expansion of the speed range while maintaining low torque). This embodiment of the invention assumes that the efficiency in the region where the oil pump strategy is not changed remains unchanged. By initially identifying a certain percentage of the efficiency region (percentage a%), the area range within the minimum area can be quickly determined (avoiding excessive changes in operating conditions, which would increase the difficulty of implementation); the average optimization percentage b% at each point in the optimization region is then confirmed through calculation. For example, taking CLTC (China Light Vehicle Test Cycle) as an example, through dynamic simulation, inputting the operating condition (CLTC) and parameters such as the vehicle resistance curve, tire radius, and reducer ratio, the electric drive output speed, torque, and time point information of a specified vehicle model under the CLTC condition can be obtained. (Reference) Figures 3-7 As shown, Figure 3 This is a schematic diagram of vehicle speed changes under CLTC conditions in an embodiment of the present invention. Figure 4 This is a schematic diagram of the motor torque under CLTC operating conditions in an embodiment of the present invention. Figure 5 This is a schematic diagram of the motor speed under CLTC operating conditions in an embodiment of the present invention. Figure 6 This is a schematic diagram of the discretized point plot of motor torque under CLTC operating condition in an embodiment of the present invention. Figure 7 This is a schematic diagram of the discretized point plot of motor speed under the CLTC operating condition in an embodiment of the present invention. Through discretization data processing, torque and speed are discretized into point plots. With a certain tolerance, the number of points in each region is statistically analyzed to determine the proportion of points in each region under the specified operating condition, as shown in Tables 1 and 2 below. Table 1 shows the number of points in each region under the specified operating condition, where different regions represent different motor torque and speed ranges. In Table 1, the first row represents the speed range, the first column represents the torque range, and the middle column shows the number of points. Table 2 shows the proportion of points in each region under the specified operating condition. In Table 2, the first row represents the speed range, the first column represents the torque range, and the middle column shows the proportion. For example, if the CLTC efficiency needs to be improved from 90% to 91%, an improvement of 1% (a%) is required. With the goal of optimizing 50% of the operating conditions, the following area of ​​operating conditions is initially identified for optimization. Based on the percentage of points in this area, it can be determined that the average efficiency of points in the optimization area needs to be improved by 2% (b%). The 50% operating conditions can be approximated as 24.8%, 15%, and 12% in Table 2, corresponding to speed ranges of 0–2000 rpm and torque ranges of 0–20 Nm. It should be noted that the data in Table 2 is the operating data, which includes multiple sub-data points. For example, one sub-data point might be: motor speed range 0–500 rpm, motor torque range 0–20 Nm, and the corresponding duration percentage is 24.8%.

[0074] Table 1:

[0075]

[0076] Table 2:

[0077]

[0078] It should be noted that in obtaining the target lubricating oil temperature required by the reducer of the electric drive system during the current start-stop cycle, reference is made to... Figure 8 As shown, Figure 8 This is a schematic diagram of the second correspondence in an embodiment of the present invention. Based on the reducer efficiency at different oil temperatures, it can be determined whether there is potential for improving the reducer efficiency in the initial optimization region. If the reducer efficiency at a specified temperature is lower than that at higher oil temperatures, and the average efficiency difference exceeds the optimization target b%, the target oil temperature for each point within the region is locked. If the difference between the target oil temperature and the initial oil temperature is large (e.g., exceeding 20°C), the first torque range and the first speed range need to be redefined. If no relevant region meets the requirements through iteration, the optimization target needs to be redefined.

[0079] The following examples illustrate the second start-up and second stop durations: If the NTC temperature is no greater than 20℃ and greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 1kW, then the second stop duration can be 30s, and the second start-up duration can be 10s; if the NTC temperature is no greater than 20℃ and greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 3kW, then the second stop duration can be 15s, and the second start-up duration can be 10s; if the NTC temperature is no greater than 20℃ and greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 5kW, then the second stop duration can be 10s. The second start-up time can be 10 seconds; if the NTC temperature is no greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 1kW, then the second stop time can be 30 seconds, and the second start-up time can be 30 seconds; if the NTC temperature is no greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 3kW, then the second stop time can be 15 seconds, and the second start-up time can be 30 seconds; if the NTC temperature is no greater than 0℃, the motor speed is no greater than 4000rpm, the motor torque is no greater than 30Nm, and the reducer power is no greater than 5kW, then the second stop time can be 10 seconds, and the second start-up time can be 30 seconds.

[0080] This invention, in its embodiments, acquires the current lubricating oil temperature of the vehicle's electric drive system. If the current lubricating oil temperature is lower than a preset temperature threshold, it acquires at least one operating parameter of the vehicle. If at least one operating parameter is within a preset parameter range, it performs alternating start-stop control on the oil pump of the electric drive system. When the oil pump is running, it pumps out some lubricating oil from inside the reducer, reducing the amount of oil churning inside the reducer. When the oil pump is stopped, the lubricating oil flows back into the reducer, increasing the amount of oil churning inside the reducer. Therefore, by alternating start-stop control of the oil pump, it prevents the pump from being continuously running, thereby increasing the amount of oil churning inside the reducer. This accelerates the temperature rise of the lubricating oil in the electric drive system, reducing the viscosity of the lubricating oil and forming an effective oil film between the gears of the reducer, reducing friction and improving the reducer efficiency. Thus, the efficiency of the electric drive system is improved.

[0081] Based on the same inventive concept, and referring to Figure 9As shown, an embodiment of the present invention provides a control device 10 for an electric drive system of a vehicle, comprising: a temperature acquisition unit 110 for acquiring the current lubricating oil temperature of the electric drive system of the vehicle; a parameter acquisition unit 120 for acquiring at least one operating parameter of the vehicle if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold; and a start-stop control unit 130 for performing start-stop alternating control of the oil pump of the electric drive system if at least one operating parameter is within a preset parameter range.

[0082] It is understood that the temperature acquisition unit 110 is specifically used to: acquire the current motor temperature of the electric drive system; input the current motor temperature into a preset first correspondence relationship to obtain the current lubricating oil temperature of the electric drive system, wherein the first correspondence relationship is the correspondence between the motor temperature and the lubricating oil temperature.

[0083] It is understood that the start-stop control unit 130 includes: an alternating control subunit, used to perform alternating start-stop control on the oil pump of the electric drive system based on a first start duration and a first stop duration if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold; and a maintenance control subunit, used to maintain the oil pump in the start state if the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold.

[0084] It should be noted that the first start-up time is the lubrication time required for the bearing of the electric drive system to switch from the extreme lean oil state to the fully lubricated state. The extreme lean oil state is the bearing state corresponding to the deviation between the lubricating oil quantity of the bearing in the electric drive system and the first preset oil quantity is less than the preset first oil quantity deviation threshold. The fully lubricated state is the bearing state corresponding to the deviation between the lubricating oil quantity of the bearing in the electric drive system and the second preset oil quantity is less than the preset second oil quantity deviation threshold. The second preset oil quantity is greater than the first preset oil quantity.

[0085] The first stop duration is the sum of the first sub-duration and the second sub-duration. The first sub-duration is the duration during which the bearing of the electric drive system can operate smoothly under extreme lean oil conditions. The second sub-duration is the duration during which the lubricating oil quantity of the bearing of the electric drive system decreases from the second preset oil quantity to the first preset oil quantity when the oil pump of the electric drive system is stopped.

[0086] In some implementations, the alternating control subunit is specifically used to: control the oil pump of the electric drive system to start running for a first start-up duration, control the oil pump of the electric drive system to stop for a first stop duration, and then control the oil pump of the electric drive system to restart.

[0087] In other embodiments, the alternating control subunit is specifically used to: obtain the target lubricating oil temperature required by the reducer of the electric drive system during the current start-stop cycle; based on the target lubricating oil temperature and the current lubricating oil temperature, correct the first start duration and the first stop duration to obtain a second start duration and a second stop duration, wherein the second stop duration is less than or equal to the first stop duration; and during the current start-stop cycle, perform a start-stop control on the oil pump based on the second start duration and the second stop duration to raise the lubricating oil temperature of the electric drive system from the current lubricating oil temperature to the target lubricating oil temperature.

[0088] It is understood that at least one operating parameter includes the motor torque and motor speed of the electric drive system. Therefore, the control device 10 of the electric drive system of the vehicle further includes: a range determination unit, used to determine that at least one operating parameter is within a preset parameter range if the motor torque of the electric drive system is within a preset first torque range and the motor speed of the electric drive system is within a preset first speed range.

[0089] It is understood that the control device 10 of the vehicle's electric drive system also includes: a range acquisition unit, used to pre-acquire a first torque range and a first speed range; the range acquisition unit is specifically used to: acquire operating data obtained from testing the vehicle, the operating data including multiple operating sub-data, each operating sub-data including operating information and the corresponding duration ratio of the operating information, the operating information including the motor torque range and motor speed range of the electric drive system; determine a second torque range and a second speed range based on the operating data; within the second torque range and the second speed range, acquire a first degree of damage when the bearing of the electric drive system is in an extreme lean state; and determine the first torque range and the first speed range based on the first degree of damage, a preset damage degree threshold, the second torque range, and the second speed range.

[0090] It should be understood that further implementation details of the control device 10 of the electric drive system of the vehicle in the embodiments of the present invention are described in the foregoing control method of the electric drive system of the vehicle, and will not be repeated here for the sake of brevity.

[0091] Based on the same inventive concept, embodiments of the present invention also provide an electronic device, such as... Figure 10 As shown, the system includes a memory 1004, a processor 1002, and a computer program stored in the memory 1004 and executable on the processor 1002. The processor 1002 executes the program to implement the steps described in any embodiment of the control method for the electric drive system of the vehicle.

[0092] Among them, Figure 10In this document, a bus architecture (represented by bus 1000) is used. Bus 1000 may include any number of interconnected buses and bridges, linking various circuits including one or more processors represented by processor 1002 and memory represented by memory 1004. Bus 1000 may also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. Bus interface 1005 provides an interface between bus 1000 and receiver 1001 and transmitter 1003. Receiver 1001 and transmitter 1003 may be the same element, i.e., a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 1002 is responsible for managing bus 1000 and general processing, while memory 1004 may be used to store data used by processor 1002 during operation.

[0093] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored as one or more instructions or codes on or transmitted via a computer-readable medium. Other examples and embodiments are within the scope and spirit of this invention and the appended claims. For example, due to the nature of software, the functions described above can be implemented using software executed by a processor, hardware, firmware, hardwired, or any combination thereof. Furthermore, the functional units can be integrated into a single processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit.

[0094] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0095] The units described as separate components may or may not be physically separate. Similarly, the components of the control device may or may not be physical units; they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0096] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0097] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A control method of an electric drive system of a vehicle, characterized by, The method comprises: obtaining a current lubricating oil temperature of an electric drive system of a vehicle; if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold, obtaining at least one operating parameter of the vehicle; if the at least one operating parameter is within a preset parameter range, performing start-stop alternating control on an oil pump of the electric drive system, including: if the current lubricating oil temperature of the electric drive system is less than the preset temperature threshold, performing start-stop alternating control on the oil pump of the electric drive system based on a first start time length and a first stop time length; and if the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold, maintaining the oil pump in a start state; wherein the at least one operating parameter being within the preset parameter range indicates that a bearing load of the electric drive system is less than a preset load threshold, and the at least one operating parameter includes a motor torque and / or a motor speed of the electric drive system.

2. The control method of an electric drive system of a vehicle according to claim 1, characterized by, The method comprises: obtaining a current motor temperature of the electric drive system; inputting the current motor temperature into a preset first correspondence relationship to obtain the current lubricating oil temperature of the electric drive system, the first correspondence relationship being a correspondence relationship between a motor temperature and a lubricating oil temperature.

3. The control method of the electric drive system of the vehicle according to claim 1, wherein the first start time length is a lubricating time length required for a bearing of the electric drive system to switch from a limit lean oil state to a sufficient lubrication state, the limit lean oil state being a bearing state corresponding to a situation where a deviation between a lubricating oil amount of the bearing of the electric drive system and a first preset oil amount is less than a preset first oil amount deviation threshold, and the sufficient lubrication state being a bearing state corresponding to a situation where a deviation between the lubricating oil amount of the bearing of the electric drive system and a second preset oil amount is less than a preset second oil amount deviation threshold, the second preset oil amount being greater than the first preset oil amount; the first stop time length is a sum of a first sub time length and a second sub time length, wherein the first sub time length is a time length during which the bearing of the electric drive system can operate smoothly in the limit lean oil state, and the second sub time length is a time length during which the lubricating oil amount of the bearing of the electric drive system decreases from the second preset oil amount to the first preset oil amount when the oil pump of the electric drive system is in a stop state.

4. The control method of an electric drive system of a vehicle according to claim 3, characterized by, The start-stop alternating control on the oil pump of the electric drive system based on the first start time length and the first stop time length comprises: controlling the oil pump of the electric drive system to start operating for the first start time length, then controlling the oil pump of the electric drive system to stop for the first stop time length, and then controlling the oil pump of the electric drive system to restart.

5. The control method of an electric drive system of a vehicle according to claim 3, characterized by, The start-stop alternating control on the oil pump of the electric drive system based on the first start time length and the first stop time length comprises: obtaining a target lubricating oil temperature required for a reducer of the electric drive system in a current start-stop cycle; based on the target lubricating oil temperature and the current lubricating oil temperature, correcting the first start time length and the first stop time length to obtain a second start time length and a second stop time length, the second stop time length being less than or equal to the first stop time length; In the current start-stop cycle, the oil pump is controlled to start and stop once based on the second start duration and the second stop duration, so that the lubricating oil temperature of the electric drive system rises from the current lubricating oil temperature to the target lubricating oil temperature.

6. The control method of an electric drive system of a vehicle according to any one of claims 3 to 5, characterized by, The at least one operating parameter includes a motor torque and a motor speed of the electric drive system, and the method further includes: If the motor torque of the electric drive system is in a preset first torque range and the motor speed of the electric drive system is in a preset first speed range, it is determined that the at least one operating parameter is in the preset parameter range.

7. The control method of an electric drive system of a vehicle according to claim 6, characterized by, The first torque range and the first speed range are obtained in advance by the following steps: Obtain operating data obtained by testing the vehicle, the operating data including a plurality of operating sub-data, each operating sub-data including operating information and a time proportion corresponding to the operating information, the operating information including a motor torque range and a motor speed range of the electric drive system; Based on the operating data, determine a second torque range and a second speed range; Within the second torque range and the second speed range, obtain a first damage degree when the bearing of the electric drive system is in the extreme lean oil state; Based on the first damage degree, a preset damage degree threshold, the second torque range and the second speed range, determine the first torque range and the first speed range.

8. A control device of an electric drive system of a vehicle, characterized by, Comprise: A temperature acquisition unit configured to acquire a current lubricating oil temperature of an electric drive system of a vehicle; A parameter acquisition unit configured to acquire at least one operating parameter of the vehicle if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold; A start-stop control unit configured to control an oil pump of the electric drive system to start and stop alternately if the at least one operating parameter is in a preset parameter range, including: if the current lubricating oil temperature of the electric drive system is less than the preset temperature threshold, controlling the oil pump of the electric drive system to start and stop alternately based on a first start duration and a first stop duration; if the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold, maintaining the oil pump in a start state; wherein the at least one operating parameter being in the preset parameter range indicates that a bearing load of the electric drive system is less than a preset load threshold, and the at least one operating parameter includes a motor torque and / or a motor speed of the electric drive system.

9. An electronic device, comprising: Comprise: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor implementing the method of any one of claims 1-7 when executing the computer program.

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