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

Abstract

The invention discloses a control method, device and equipment for an electric drive system of a vehicle. The method comprises the steps that the current lubricating oil temperature of the electric drive system of the vehicle is obtained; if the current lubricating oil temperature of the electric drive system is smaller than the preset temperature threshold value, at least one operation parameter of the vehicle is obtained; and if at least one operation parameter is within the preset parameter range, starting and stopping alternating control is conducted on an oil pump of the electric drive system. The technical problem that an electric drive system is low in efficiency is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control, and in particular relates to a control method, device and equipment for an electric drive system of a vehicle. Background Art

[0002] With the rapid development of electric vehicles, the low-temperature endurance problem exposed by electric vehicles has attracted more and more attention from all walks of life. In low-temperature environments, in addition to the obvious decrease in battery power output and the increase in power consumption due to other thermal management requirements, the efficiency of the electric drive system has also dropped significantly. The low-temperature efficiency loss of the electric drive system mainly includes the losses of the three major components: the motor, electronic control, and reducer. The reducer loss at low temperatures accounts for a large part of the electric drive efficiency loss, especially in the early stage of low-temperature operation.

[0003] The main reason for the loss of reducer efficiency is that in the initial stage of vehicle driving, the lubricating oil temperature in the reducer is low, resulting in high viscosity of the lubricating oil, so the lubricating oil has poor fluidity and it is difficult to form an effective oil film between the gears, which increases friction and reduces the efficiency of the reducer. The low efficiency of the reducer leads to low efficiency of the electric drive system, increases energy loss, and reduces user experience. Therefore, the low efficiency of the electric drive system is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The embodiments of the present invention provide a control method, device and equipment for an electric drive system of a vehicle, which solve the technical problem of low efficiency of the electric drive system.

[0005] In a first aspect, an embodiment of the present invention provides a method for controlling an electric drive system of a vehicle, comprising: obtaining a 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, 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 the oil pump of the electric drive system.

[0006] In combination 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 corresponding relationship to obtain the current lubricating oil temperature of the electric drive system, the first corresponding relationship being the corresponding relationship between the motor temperature and the lubricating oil temperature.

[0007] In combination with the first aspect of the present invention, in some embodiments, the start-stop alternating control of the oil pump of the electric drive system includes: if the current lubricating oil temperature of the electric drive system is lower than the preset temperature threshold, the start-stop alternating control of the oil pump of the electric drive system is performed 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, the oil pump is maintained in a started state.

[0008] In combination with the first aspect of the present invention, in some embodiments, the first startup duration is the lubrication duration required for the bearing of the electric drive system to switch from an extreme oil-poor state to a fully lubricated state, the extreme oil-poor state is a bearing state corresponding to when the deviation between the lubricating oil amount of the bearing of the electric drive system and the first preset oil amount is less than the preset first oil amount deviation threshold, the fully lubricated state is a bearing state corresponding to when the deviation between the lubricating oil amount of the bearing of the electric drive system and the second preset oil amount is less than the preset second oil amount deviation threshold, and 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, wherein the first sub-duration is the duration during which the bearing of the electric drive system can operate smoothly in the extreme oil-poor state, and the second sub-duration is the duration during which the lubricating oil amount of the bearing of the electric drive system is reduced 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 combination with the first aspect of the present invention, in some embodiments, the start-stop alternating control of the oil pump of the electric drive system based on the first start duration and the first stop duration includes: controlling the oil pump of the electric drive system to start and run for the first start duration, controlling the oil pump of the electric drive system to stop for the first stop time, and re-controlling the oil pump of the electric drive system to restart.

[0010] In combination 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 the first start duration and the first stop duration includes: obtaining the target lubricating oil temperature required for the reducer of the electric drive system in the current start-stop cycle; based on the target lubricating oil temperature and the current lubricating oil temperature, correcting the first start duration and the first stop duration to obtain a second start duration and a second stop duration, the second stop duration being less than or equal to the first stop duration; in the current start-stop cycle, starting and stopping the oil pump once based on the second start duration and the second stop duration to increase the lubricating oil temperature of the electric drive system from the current lubricating oil temperature to the target lubricating oil temperature.

[0011] In combination with the first aspect of the present invention, in some embodiments, the at least one operating parameter includes the motor torque and the 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 combination with the first aspect of the present invention, in some embodiments, the first torque range and the first speed range are pre-acquired through the following steps: obtaining operating data obtained by testing the vehicle, the operating data including multiple operating sub-data, each of the operating sub-data including operating information and a time ratio corresponding to the operating information, the operating information including the motor torque range and motor speed range of the electric drive system; based on the operating data, determining a second torque range and a second speed range; within the second torque range and the second speed range, obtaining a first damage degree of the bearing of the electric drive system when it is in the extreme oil-poor state; based on the first damage degree, a preset damage degree threshold, the second torque range and the second speed range, determining the first torque range and the first speed range.

[0013] In a second aspect, an embodiment of the present invention provides a control device for an electric drive system of a vehicle, comprising: a temperature acquisition unit, for acquiring a 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 alternating start-stop control on an oil pump of the electric drive system if the at least one operating parameter is within a preset parameter range.

[0014] In a third aspect, an embodiment of the present invention provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any one of the methods described in the first aspect when executing the computer program.

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

[0016] The embodiment of the present invention obtains 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, obtains at least one operating parameter of the vehicle; if at least one operating parameter is within the preset parameter range, the oil pump of the electric drive system is started and stopped alternately. When the oil pump is in the starting state, the oil pump will pump out part of the lubricating oil inside the reducer, reducing the amount of oil stirring inside the reducer. When the oil pump is in the stopping state, the lubricating oil flows back into the reducer, increasing the amount of oil stirring inside the reducer. Therefore, by starting and stopping the oil pump alternately, the oil pump will not always be in the starting state, thereby increasing the amount of oil stirring inside the reducer, accelerating the heating rate of the lubricating oil in the electric drive system, and further reducing the viscosity of the lubricating oil, forming an effective oil film between the gears of the reducer, reducing friction, and improving the efficiency of the reducer. Therefore, the efficiency of the electric drive system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a flow chart of a method for controlling an electric drive system of a vehicle in an embodiment of the present invention;

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

[0020] Figure 3 Schematic diagram of vehicle speed change under CLTC working condition in an embodiment of the present invention;

[0021] Figure 4 Schematic diagram of motor torque under CLTC working condition in an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of the motor speed under CLTC working condition in an embodiment of the present invention;

[0023] Figure 6 Schematic diagram of a discretization point diagram of motor torque under CLTC working condition in an embodiment of the present invention;

[0024] Figure 7 Schematic diagram of a motor speed discretization point diagram under CLTC working conditions in an embodiment of the present invention;

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

[0026] Fig. 9 is a functional module diagram of a control device for an electric drive system of a vehicle in an embodiment of the present invention;

[0027] Fig.10 Schematic diagram of the structure of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] The embodiment of the present invention provides a control method for an electric drive system of a vehicle, referring to Figure 1 As shown, the method includes the following steps S101 to S103:

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

[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 embodiments, 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 corresponding relationship to obtain the current lubricating oil temperature of the electric drive system, the first corresponding relationship being the corresponding relationship between the motor temperature and the lubricating oil temperature.

[0034] In some embodiments, a resistance temperature sensor is provided on the motor of the electric drive system, and obtaining the current motor temperature of the electric drive system may include: obtaining the current motor temperature of the electric drive system through the resistance temperature sensor. The resistance temperature sensor may 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, and the motor NTC temperature corresponding to the initial oil temperature of the reducer lubricating oil can be matched with the target oil temperature through the NTC temperature in the motor. In addition, the current motor temperature is obtained through the resistance temperature sensor on the motor, and the lubricating oil temperature is determined based on the current motor temperature, avoiding the need to add additional sensors to detect the lubricating oil temperature and reducing the dependence on hardware.

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

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

[0038] S103: If at least one operating parameter is within a preset parameter range, the oil pump of the electric drive system is started and stopped alternately.

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

[0040] In some embodiments, the start-stop alternating control of the oil pump of the electric drive system may include: if the current lubricating oil temperature of the electric drive system is less than a preset temperature threshold, the start-stop alternating control of the oil pump of the electric drive system is performed 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 started state.

[0041] In some embodiments, the first startup duration is the lubrication duration required for the bearing of the electric drive system to switch from an extremely oil-poor state to a fully lubricated state, the extremely oil-poor state is a bearing state corresponding to when the deviation between the lubricating oil quantity of the bearing of 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 a bearing state corresponding to when the deviation between the lubricating oil quantity of the bearing of the electric drive system and the second preset oil quantity is less than the preset second oil quantity deviation threshold, and the second preset oil quantity is greater than the first preset oil quantity; the first stop duration is the sum of the first sub-duration and the 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 extremely oil-poor state, and the second sub-duration is the duration during which the lubricating oil quantity of the bearing of the electric drive system is reduced from the second preset oil quantity to the first preset oil quantity when the oil pump of the electric drive system is in a stopped state.

[0042] It should be noted that during the start-stop process, increasing the stop time can increase the amount of oil stirred by the reducer, thereby quickly raising the oil temperature, but the stop time cannot be increased indefinitely. Because when the oil pump is in a stopped state, the lubricating oil flows back to the reducer, the amount of lubricating oil in the bearings of the electric drive system is reduced, and the degree of bearing damage increases. If it is reduced to a certain threshold, the safe operation of the bearings may not be guaranteed. Therefore, the embodiment of the present invention determines the start-up time and stop time according to the extreme oil-poor state and sufficient lubrication state of the bearing, avoiding damage to the bearing due to excessive stop time of the oil pump, and achieving the beneficial effect of both accelerating the heating rate of the lubricating oil and ensuring the safety of the electric drive system.

[0043] refer to Figure 2 As shown, Figure 2 FIG. 1 is a schematic diagram of the oil pump operation stage in an embodiment of the present invention, 0 It can be the first preset oil volume, l 1 It can be the second preset oil quantity, t 0 is the first sub-period, t 1 is the first startup duration, t 2 The second sub-duration, the above time and lubricating oil quantity can be confirmed by simulation calculation or single body test of the bearing supplier.

[0044] In some embodiments, the start-stop alternating control of the oil pump of the electric drive system based on the first start duration and the first stop duration may include: controlling the oil pump of the electric drive system to start and run for a first start duration, controlling the oil pump of the electric drive system to stop for a first stop duration, and re-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 duration and the first stop duration may include the following steps S1031 to S1033:

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

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

[0048] In some embodiments, determining the target lubricating oil temperature based on a preset second correspondence, a target efficiency increment, and a 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 a current efficiency of the reducer; determining a 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 a target lubricating oil temperature.

[0049] S1032: Based on the target lubricating oil temperature and the current lubricating oil temperature, the first start duration and the first stop duration are corrected 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.

[0050] Specifically, referring to the following equations (1) to (4), the correction process can refer to the following steps 1 to 3: Step 1, pre-acquire relevant parameters. Specifically, when at least one operating parameter is within the corresponding working condition of the preset parameter range, assuming l 2 The amount of oil stirred by the reducer when the oil pump is started at this working point, l 3 P is the oil stirring amount of the reducer when the oil pump is not started at this working point. 0 is the reducer power under this condition, and the reducer oil stirring amount is determined by simulation or experiment. 2 and l 3 The following correspond to the reducer efficiency η 1 and η 2 ; The increase in efficiency loss caused by starting and shutting down the oil pump is η 2 -η 1 This increased efficiency loss heats the lubricating oil in the form of heat, causing the lubricating oil to heat up faster, and can increase the heating power: P 0 ×(η 2 -η 1 ). Step 2, the third start duration can be a duration greater than or equal to the first start duration. Each time a different third start duration is selected and input into formula (1), a corresponding third stop duration can be obtained. According to the third start duration and the third stop duration corresponding to the third start duration, a set of start and stop durations can be obtained. Repeatedly select different third start durations and input them into formula (1) to obtain multiple sets of start and stop durations. Step 3, according to formula (4), for each set of start and stop durations in the multiple sets of start and stop durations, substitute into formula (4) to obtain a proportional value. The set of start and stop durations corresponding to the largest proportional value is used as the target set start and stop duration, the third start duration of the target set start and stop duration is used as the second start duration, and the third stop duration of the target set start and stop duration is equal to the minimum value of the first stop duration as the second stop duration.

[0051] ρ×l 3 ×c×(T 1 -T0 )=(P 0 ×η 1 ×t 3 )+(P 0 ×η 2 ×t 4 ) (1);

[0052] Q = m × c × (T 1 -T 0 ) (2);

[0053] m = ρ × v (3);

[0054]

[0055] Where m is the weight of the lubricating oil, Q is the heat of heating of the lubricating oil, c is the specific heat capacity of the lubricating oil, ρ is the density of the lubricating oil, v is the volume of the lubricating oil, T 0 is the current lubricating oil temperature, T 1 is the target lubricating oil temperature, l 3 The oil stirring amount of the reducer when the oil pump is not started at this working point, η 1 The oil stirring amount in the reducer is l 2 The reducer efficiency at 2 The oil stirring amount in the reducer is l 3 The reducer efficiency at 2 The oil stirring amount of the reducer when the oil pump is started at this working point, t 3 is the third start-up duration, t 4 is the third stop time, P 0 is the reducer power under this condition.

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

[0057] In some embodiments, the oil pump is started and stopped based on the second start time and the second stop time, which may be: after controlling the oil pump of the electric drive system to start running for the second start time, the oil pump of the electric drive system is controlled to stop for the second stop time.

[0058] It should be noted that the longer the oil pump is stopped, the faster the lubricating oil will heat up, the greater the efficiency of the reducer will be, but the damage to the bearings of the electric drive system will also be greater. Therefore, the longer the oil pump is stopped, the better. The embodiment of the present invention limits the determination of the target lubricating oil temperature according to the target efficiency increment of the reducer, and then corrects the stop time of the oil pump. This not only improves the efficiency of the reducer and achieves the beneficial effect of accurately controlling the efficiency of the reducer, but also reduces the degree of damage to the bearings of the electric drive system. Therefore, the beneficial effects of both improving the efficiency of the reducer and reducing the degree of damage to the bearings of the electric drive system are achieved.

[0059] In some embodiments, at least one operating parameter includes the motor torque and motor speed of the electric drive system. Then, 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 embodiments, the first torque range and the first speed range are pre-acquired by the following steps, including the following steps A to D:

[0061] Step A: Acquire operating data obtained by testing the vehicle, the operating data including multiple operating sub-data, each operating sub-data including operating information and a duration ratio corresponding to the operating information, and the operating information includes a motor torque range and a motor speed range of the electric drive system.

[0062] Step B: Determine a second torque range and a second speed range based on the operating data.

[0063] In some embodiments, step B may include: selecting part of the operating sub-data from multiple operating sub-data of the operating data, the deviation between the sum of the time ratios of each operating sub-data in the part of the operating sub-data and the preset time ratio is less than a preset ratio deviation threshold; performing a union operation on the motor torque range of each operating sub-data in the part of the operating sub-data to obtain a second torque range, the deviation between the lower limit value of the second torque range and zero is less than the preset torque deviation threshold, and the torque value of the second torque range is continuous; performing a union operation on the motor speed range of each operating sub-data in the part of the operating sub-data to obtain a second speed range, the deviation between the lower limit value of the second speed range and zero is less than the preset speed deviation threshold, and the speed value of the second speed range is continuous.

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

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

[0066] It should be noted that the first damage degree may be obtained from a preset corresponding relationship, and the preset corresponding relationship may be a corresponding relationship between a torque range, a speed range, and a damage degree.

[0067] Step D: Determine a first torque range and a first speed range based on the first damage degree, a preset damage degree threshold, a second torque range and a second speed range.

[0068] In some embodiments, step D may include: if the first damage degree is greater than a preset damage degree threshold, reducing the upper limit value of the second torque range to obtain the first torque range, and reducing the upper limit value of the second speed range to obtain the first speed range; wherein, under the first torque range and the first speed range, the second damage degree of the bearing of the electric drive system in the extreme oil-poor state is less than or equal to the preset damage degree threshold; if the first damage degree 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 according to the degree of damage, the total operating time of the operating point in the optimization area can be determined according to the customer operating conditions of the vehicle throughout its life cycle, and the bearing damage c% in the optimization area under the original lubrication condition is calculated. The bearing damage d% is calculated under the extreme oil-poor condition. The damage e% of each bearing in the entire life cycle under the durability load spectrum is calculated. If the bearing damage (e-c+d)% under the extreme oil-poor condition in the optimization area exceeds the design life of the bearing, the optimization interval is narrowed, and the final optimization interval is obtained by combining the intersection of the optimization areas confirmed previously.

[0070] It should be noted that the oil pump of the electric drive system will be started and stopped alternately only in the first torque range and the first speed range. However, the start-stop alternating control will cause damage to the bearings of the electric drive system. If the degree of damage is too large, the operational safety of the electric drive system will be reduced. Therefore, the embodiment of the present invention limits the determination of the first torque range and the first speed range based on the first damage degree, the preset damage degree threshold, the second torque range and the second speed range, thereby avoiding the damage degree being greater than the preset damage degree threshold, ensuring the safe operation of the bearing, and further ensuring the operational safety of the electric drive system.

[0071] It should be noted that the specific application scenario of the embodiment of the present invention may be the initial stage of vehicle driving. In this stage, the current lubricating oil temperature of the electric drive system is less than the preset temperature threshold, the vehicle speed is less than the preset speed threshold, and the throttle opening of the vehicle is less than the preset opening threshold, that is, the low temperature, low speed and low load scenario. The initial stage of driving may refer to the corresponding stage from the start time of the vehicle to half an hour after the start time of driving. In the low temperature, low speed and low load scenario, the bearing load of the electric drive system is small and the damage is small, so the lubricating oil demand of the bearing is low. At this time, the oil pump can be started and stopped to increase the stop time of the oil pump. Even if the lubricating oil amount of the bearing is low, it will not cause excessive damage. Therefore, in order to accurately identify the low temperature, low speed and low load scenario, the embodiment of the present invention can be judged by the lubricating oil temperature and operating parameters. In particular, for operating parameters, combining motor torque and motor speed can better judge the vehicle status and accurately identify scenarios. For example, when the vehicle is heavily loaded, the throttle is large but the speed is low, although the motor speed is low, the torque is large, and it does not belong to the low temperature, low speed and low load scenario. At this time, the bearing load is large, and if the oil pump is started and stopped, it may cause serious damage to the bearing. Therefore, relying solely on a certain operating parameter may lead to misjudgment. In order to improve the accuracy of vehicle status judgment, the embodiment of the present invention limits the judgment to a combination of motor torque and motor speed, thereby achieving the beneficial effect of improving the accuracy of vehicle status judgment. Furthermore, since the vehicle status is accurately judged, the situation of causing serious damage to the bearing due to the start and stop control of the oil pump is avoided, so the safe operation of the bearing is guaranteed.

[0072] It should be noted that the embodiments of the present invention can be aimed at optimizing the low-temperature loss of oil-cooled electric drive reducers. By optimizing the electronic oil pump control strategy, the oil pump is turned off under certain working conditions to increase the oil stirring, and at the same time the temperature of the motor body is increased. Intermittent oil pumping is used to ensure the basic lubrication of the motor and take away the heat generated by the motor, so that the lubricating oil rises rapidly under low temperature conditions, thereby achieving an improvement in the efficiency of the electric drive under low temperature conditions. Under low temperature, low speed and low load conditions, the oil pump start and stop control is controlled, so that while ensuring the basic lubrication of bearings and gears, the reducer stirs the oil more time, and the reducer lubricating oil temperature is increased faster, thereby reducing the viscosity of the lubricating oil; at the same time, due to the start and 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 will be significantly reduced, thereby causing the temperature of the motor stator and rotor to rise, improving the motor efficiency, so that the low-temperature efficiency of the electric drive can be further improved. The problem of low efficiency and high energy consumption of the reducer is solved, and the problem of low low-temperature endurance of electric vehicles is greatly improved.

[0073] The following is a further explanation of the process of obtaining operating data: In the following examples, the speed unit is rpm, and the torque unit is Nm. According to the working condition that needs to be optimized, the torque, speed, and time point signal information under the optimized working condition are clearly output through dynamic simulation software or real vehicle collection; the speed and torque signal obtained at this time is a continuous signal, and the data is effectively discretized in a certain step through data discretization to facilitate statistical confirmation of the number of working condition points under each speed and torque (operating time under each speed and torque) and then confirm the operating time ratio under each working condition. Based on the original working condition efficiency and the working condition efficiency optimization target, the target to be improved is determined; low speed and small torque are used as the optimization target of this solution, and the efficiency of the low speed and small torque area is improved by optimizing and improving the efficiency; for the working condition in the non-optimized area, the oil pump strategy is not used, and the original oil pump strategy continues to be used. Expand outward from the minimum origin as the starting point, mainly changing the speed (that is, giving priority to expanding the speed range and maintaining small torque); the embodiment of the present invention assumes that the efficiency of the oil pump strategy area remains unchanged. By initially locking in a certain percentage of the efficiency area (accounting for a%), the area range under the minimum area can be quickly locked (avoiding too many changes in operating points, which increases the difficulty of implementation); the average optimization percentage b% of each point in the optimization area is confirmed by calculation. For example: Taking CLTC (China Light Vehicle Test Cycle) as an example, through dynamic simulation, the operating conditions (CLTC) and vehicle resistance curve, tire radius, reducer ratio and other parameters are input to obtain the electric drive output speed, torque, and time point information of the specified model under CLTC conditions. Reference Figure 3 to Figure 7 As shown, Figure 3 Schematic diagram of vehicle speed change under CLTC working condition in an embodiment of the present invention, Figure 4 Schematic diagram of motor torque under CLTC working condition in an embodiment of the present invention, Figure 5 Schematic diagram of the motor speed under CLTC working condition in an embodiment of the present invention, Figure 6 Schematic diagram of a motor torque discretization point diagram under CLTC working conditions in an embodiment of the present invention, Figure 7 It is a schematic diagram of the discretization point diagram of the motor speed under the CLTC working condition in the embodiment of the present invention. Through discretization data processing, the torque and speed are discretized, and the torque and speed are discretized into individual point diagrams. The number of landing points in each area is counted with a certain tolerance to determine the proportion of landing points in each area under the specified working condition. Refer to Table 1 and Table 2 below. Table 1 shows the number of landing points in each area under the specified working condition, where different areas represent different motor torque ranges and motor speed ranges. The first line in Table 1 is the speed range, the first column is the torque range, and the middle is the number of points. Table 2 shows the proportion of landing points in each area under the specified working condition. The first line in Table 2 is the speed range, the first column is the torque range, and the middle is the proportion. For example, the CLTC efficiency needs to be increased from 90% to 91%, which requires an increase of 1% (a%). With the goal of optimizing the landing point of the 50% working condition, the following area of ​​the optimized working condition is initially locked. From the landing point ratio in this area, it can be determined that the efficiency of the points in the optimized area needs to be increased by an average of 2% (b%). The 50% working condition can be approximated to 24.8%, 15% and 12% in Table 2, and the corresponding speed range includes 0-2000rpm, and the torque range includes 0-20Nm. It should be noted that the data in Table 2 is the operating data, and the operating data includes multiple operating sub-data. For example, one of the operating sub-data is: the motor speed range is 0-500rpm, the motor torque range is 0-20Nm, and the duration ratio corresponding to the operating information is 24.8%.

[0074] Table 1:

[0075]

[0076] Table 2:

[0077]

[0078] It should be noted that in the process of obtaining the target lubricating oil temperature required by the reducer of the electric drive system in the current start-stop cycle, reference Figure 8 As shown, Figure 8 It is a schematic diagram of the second corresponding relationship in the embodiment of the present invention. According to the reducer efficiency at different oil temperatures of the reducer, it can be confirmed whether there is potential for improvement in the reducer efficiency in the initial optimization area. If the reducer efficiency at a specified temperature is lower than the efficiency at a higher oil temperature, and the average efficiency difference exceeds the optimization target b%, the target oil temperature of each point in the area is locked. If the difference between the target oil temperature and the initial oil temperature is large (for example, more than 20°C), it is necessary to redefine the first torque range and the first speed range. If no relevant area meets the requirements through iteration, it is necessary to redefine the optimization target.

[0079] The following examples illustrate the second start time and the second stop time: if the NTC temperature is not greater than 20°C and greater than 0°C, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 1Kw, the second stop time can be 30s, and the second start time can be 10s; if the NTC temperature is not greater than 20°C and greater than 0°C, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 3Kw, the second stop time can be 15s, and the second start time can be 10s; if the NTC temperature is not greater than 20°C and greater than 0°C, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 5Kw, the second stop time The second start-up time can be 10s, and the second start-up time can be 10s; if the NTC temperature is not greater than 0℃, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 1Kw, the second stop time can be 30s, and the second start-up time can be 30s; if the NTC temperature is not greater than 0℃, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 3Kw, the second stop time can be 15s, and the second start-up time can be 30s; if the NTC temperature is not greater than 0℃, the motor speed is not greater than 4000rpm, the motor torque is not greater than 30Nm, and the reducer power is not greater than 5Kw, the second stop time can be 10s, and the second start-up time can be 30s.

[0080] The embodiment of the present invention obtains 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, obtains at least one operating parameter of the vehicle; if at least one operating parameter is within the preset parameter range, the oil pump of the electric drive system is started and stopped alternately. When the oil pump is in the starting state, the oil pump will pump out part of the lubricating oil inside the reducer, reducing the amount of oil stirring inside the reducer. When the oil pump is in the stopping state, the lubricating oil flows back into the reducer, increasing the amount of oil stirring inside the reducer. Therefore, by starting and stopping the oil pump alternately, the oil pump will not always be in the starting state, thereby increasing the amount of oil stirring inside the reducer, accelerating the heating rate of the lubricating oil in the electric drive system, and further reducing the viscosity of the lubricating oil, forming an effective oil film between the gears of the reducer, reducing friction, and improving the efficiency of the reducer. Therefore, the efficiency of the electric drive system is improved.

[0081] Based on the same inventive concept, Fig. 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 a 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; a start-stop control unit 130, for performing start-stop alternating control on an oil pump of the electric drive system if at least one operating parameter is within a preset parameter range.

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

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

[0084] Among them, it should be noted that the first startup duration is the lubrication duration required for the bearing of the electric drive system to switch from an extreme oil-poor state to a fully lubricated state, the extreme oil-poor state is a bearing state corresponding to when the deviation between the lubricating oil amount of the bearing of the electric drive system and the first preset oil amount is less than a preset first oil amount deviation threshold, the fully lubricated state is a bearing state corresponding to when the deviation between the lubricating oil amount of the bearing of the electric drive system and the second preset oil amount is less than a preset second oil amount deviation threshold, and the second preset oil amount is greater than the first preset oil amount;

[0085] Among them, the first stop time is the sum of the first sub-time and the second sub-time, wherein the first sub-time is the time during which the bearings of the electric drive system can operate smoothly under the extremely lean oil state, and the second sub-time is the time during which the amount of lubricating oil in the bearings 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.

[0086] In some embodiments, 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 time, control the oil pump of the electric drive system to stop for a first stop time, and re-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 for 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, and the second stop duration is less than or equal to the first stop duration; in 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 increase the lubricating oil temperature of the electric drive system from the current lubricating oil temperature to the target lubricating oil temperature.

[0088] It can be understood that at least one operating parameter includes the motor torque and motor speed of the electric drive system. Then, the control device 10 of the electric drive system of the vehicle also includes: a range determination unit, which is 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 can be understood that the control device 10 of the vehicle's electric drive system also includes: a range acquisition unit, which is 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 by testing the vehicle, the operating data including multiple operating sub-data, each operating sub-data including operating information and a time ratio 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, acquire a first damage degree when the bearing of the electric drive system is in an extreme oil-poor 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.

[0090] It should be understood that more implementation details of the control device 10 of the electric drive system of the vehicle in the embodiment of the present invention are described in the control method of the electric drive system of the vehicle described above, and for the sake of brevity of the specification, they are not repeated here.

[0091] Based on the same inventive concept, an embodiment of the present invention further provides an electronic device, such as Fig.10 As shown, it 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 implementation of the control method for the electric drive system of the vehicle.

[0092] Among them, Fig.10In the embodiment of the present invention, a bus architecture (represented by bus 1000) is shown, bus 1000 may include any number of interconnected buses and bridges, bus 1000 links 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 peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described 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, namely 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 when performing operations.

[0093] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium or transmitted via a computer-readable medium. Other examples and implementations are within the scope and spirit of the present invention and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. In addition, each functional unit may be integrated into a processing unit, each unit may exist physically separately, or two or more units may be integrated into one 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. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0095] The units described as separate components may or may not be physically separated, and the components of the control device may or may not be physical units, that is, they may be located in one place or distributed in multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0096] If the integrated unit is implemented in the form of 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, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0097] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A control method for an electric drive system of a vehicle, characterized in that: include: Get the current lubricating oil temperature of the vehicle's electric drive system; 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, the oil pump of the electric drive system is started and stopped alternately.

2. The control method of the electric drive system of a vehicle according to claim 1, characterized in that: The obtaining of the current lubricating oil temperature of the electric drive system of the vehicle includes: Obtaining a current motor temperature of the electric drive system; The current motor temperature is input into a preset first corresponding relationship to obtain the current lubricating oil temperature of the electric drive system, where the first corresponding relationship is a corresponding relationship between the motor temperature and the lubricating oil temperature.

3. The control method of the electric drive system of a vehicle according to claim 1, characterized in that: The start-stop alternating control of the oil pump of the electric drive system includes: If the current lubricating oil temperature of the electric drive system is lower than the preset temperature threshold, the oil pump of the electric drive system is started and stopped alternately based on the first start duration and the first stop duration; If the current lubricating oil temperature of the electric drive system is greater than or equal to the preset temperature threshold, the oil pump is maintained in a started state.

4. The control method of the electric drive system of a vehicle according to claim 3, characterized in that: The first startup duration is the lubrication duration required for the bearing of the electric drive system to switch from an extreme oil-poor state to a fully lubricated state, the extreme oil-poor state is a bearing state corresponding to when a 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 a bearing state corresponding to when a 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, and 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, wherein the first sub-duration is the duration during which the bearings of the electric drive system can operate smoothly under the extreme oil-poor state, and the second sub-duration is the duration during which the amount of lubricating oil in the bearings 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.

5. The control method of the electric drive system of a vehicle according to claim 4, characterized in that: The method of performing start-stop alternating control on the oil pump of the electric drive system based on the first start duration and the first stop duration includes: After controlling the oil pump of the electric drive system to start and run for the first start time, controlling the oil pump of the electric drive system to stop for the first stop time, and re-controlling the oil pump of the electric drive system to restart.

6. The control method of the electric drive system of a vehicle according to claim 4, characterized in that: The method of performing start-stop alternating control on the oil pump of the electric drive system based on the first start duration and the first stop duration includes: Obtaining a target lubricating oil temperature required by the 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, the first start duration and the first stop duration are corrected 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; In the current start-stop cycle, the oil pump is start-stop controlled 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.

7. The control method of the electric drive system of a vehicle according to any one of claims 4 to 6, characterized in that: 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 within a preset first torque range, and the motor speed of the electric drive system is within a preset first speed range, it is determined that the at least one operating parameter is within the preset parameter range.

8. The control method of the electric drive system of a vehicle according to claim 7, characterized in that: The first torque range and the first speed range are pre-acquired by the following steps: Acquire operation data obtained by testing the vehicle, the operation data including a plurality of operation sub-data, each of the operation sub-data including operation information and a time ratio corresponding to the operation information, the operation information including a motor torque range and a motor speed range of the electric drive system; determining a second torque range and a second speed range based on the operating data; In the second torque range and the second speed range, obtaining a first damage degree of the bearing of the electric drive system when the bearing is in the extreme oil-poor state; The first torque range and the first speed range are determined based on the first damage level, a preset damage level threshold, the second torque range, and the second speed range.

9. A control device for an electric drive system of a vehicle, characterized in that: include: A temperature acquisition unit, used 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 a current lubricating oil temperature of the electric drive system is less than a preset temperature threshold; A start-stop control unit is used to perform 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.

10. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 8 when executing the computer program.

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