Oil cooling electric drive oil pump control method, controller and vehicle

Abstract

The invention relates to the field of oil pump control, in particular to an oil cooling electric drive oil pump control method, a controller and a vehicle, and aims to solve the problems that an existing oil pump control strategy is high in energy consumption, and the overall energy efficiency of an oil cooling electric drive system cannot be optimal so as to improve the energy utilization efficiency of the whole vehicle. The method comprises the steps that the current inclination angle of the vehicle and the current working torque and the current rotating speed of the oil cooling electric drive system are obtained; based on a preset oil pump control mapping table, the base oil pump rotating speed corresponding to the current working torque and the current rotating speed is determined; based on the current inclination angle, the minimum oil pump rotating speed meeting the lubricating requirement is determined; and comparing the base oil pump rotating speed with the minimum oil pump rotating speed meeting the lubrication requirement, and selecting the larger value as the target control rotating speed of the oil pump.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, specifically to an oil-cooled electric drive oil pump control method, controller, and vehicle. Background Technology

[0002] With the rapid development and market penetration of the new energy vehicle industry, the driving range of electric vehicles has become a core concern for users. To improve range, mainstream technologies focus on increasing battery capacity and improving overall vehicle energy management efficiency. However, simply increasing battery capacity leads to a significant increase in vehicle weight and cost, with diminishing marginal returns, and may negatively impact energy consumption. Therefore, given a fixed battery capacity, deeply optimizing overall vehicle energy management efficiency and improving battery capacity utilization has become a key breakthrough direction for increasing driving range.

[0003] In the overall energy consumption of a vehicle, the oil-cooled electric drive system is the main energy-consuming unit. Due to its advantages such as high cooling efficiency and compact structure, the oil-cooled electric drive system is increasingly widely used in mid-to-high-end electric vehicles. The oil-cooling solution directly cools the heat-generating components of the motor (such as the stator and rotor) through circulating cooling oil, effectively reducing the motor's operating temperature and thus improving the motor's efficiency and power output under continuous high loads.

[0004] However, the advantages of oil-cooled systems come at a cost. Driving the oil pump requires additional electrical energy, which comes directly from the vehicle's battery. Currently, the industry generally employs a relatively conservative oil pump control strategy, typically setting a high or fixed oil pump speed to ensure the cooling and lubrication safety of the oil-cooled electric drive system under the most severe operating conditions. While this strategy ensures reliability, it fails to dynamically balance and globally optimize the cooling and lubrication requirements of the oil-cooled electric drive system with the oil pump's energy consumption based on the vehicle's actual operating conditions. This results in the oil pump being in a state of overwork for extended periods, causing unnecessary energy waste and hindering further improvements in overall vehicle energy efficiency. Summary of the Invention

[0005] This application provides an oil-cooled electric drive oil pump control method, controller, and vehicle, aiming to solve the problems of high energy consumption and failure to achieve optimal overall energy efficiency of the oil-cooled electric drive system in existing oil pump control strategies, so as to improve the energy utilization efficiency of the whole vehicle.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, this application provides an oil-cooled electric drive oil pump control method, including: acquiring the current tilt angle of the vehicle, the current operating torque of the oil-cooled electric drive system, and the current speed;

[0008] Based on a preset oil pump control mapping table, a base oil pump speed corresponding to the current operating torque and current speed is determined; wherein, the oil pump control mapping table is generated in the following way: for multiple oil-cooled electric drive system operating points, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system.

[0009] Based on the current tilt angle, determine the minimum oil pump speed that meets the lubrication requirements;

[0010] The base oil pump speed is compared with the minimum oil pump speed required to meet lubrication needs, and the larger value is selected as the target control speed of the oil pump.

[0011] Based on the principles of optimizing the overall efficiency of the oil-cooled electric drive system and the oil pump, and meeting the minimum cooling requirements of the oil-cooled electric drive system, a fixed oil pump control mapping table is generated. This table defines the base oil pump speed corresponding to different current operating torques and current speeds. During actual vehicle operation, this method simultaneously performs two query actions: first, it queries the mapping table based on the real-time current operating torque and current speed to obtain the base oil pump speed; second, it determines the minimum oil pump speed that meets lubrication requirements based on the real-time current tilt angle. Finally, the two speed values ​​are compared, and the larger value is selected as the final execution target. Its core effect is to ensure that the oil pump speed at any time is not lower than both the cooling requirement benchmark based on torque / speed and the lubrication requirement benchmark based on tilt angle, thereby striving to make the system operate in a pre-calibrated optimal overall efficiency state while ensuring the safe operation of the oil-cooled electric drive system.

[0012] In some possible embodiments, the generation of the oil pump control mapping table includes:

[0013] In bench testing, various combinations of electric drive torque and electric drive speed were tested, and the following procedures were performed:

[0014] The mechanical power of the oil-cooled electric drive system, the first electrical power input to the oil-cooled electric drive system, and the second electrical power input to the oil pump were tested at different oil pump speeds.

[0015] Calculate the overall system efficiency at different oil pump speeds based on the mechanical power, the first electrical power, and the second electrical power.

[0016] The oil pump speed that maximizes the overall efficiency of the system is selected as the optimal speed for this combined operating condition.

[0017] Under the same operating conditions, the minimum oil pump speed that enables the oil-cooled electric drive system to reach thermal equilibrium is determined as the minimum cooling oil pump speed for that operating condition.

[0018] For each operating condition combination, the larger of the optimal efficiency speed and the minimum cooling requirement oil pump speed is taken as the base oil pump speed in the oil pump control mapping table for that operating condition.

[0019] The final mapping table is generated through a structured offline calibration process.

[0020] For each fixed operating point of the oil-cooled electric drive system (specific torque and speed), this method performs a comprehensive test to identify two key values ​​from all possible oil pump speeds: one is the speed at which the overall system efficiency is maximized (optimal efficiency speed), and the other is the minimum speed sufficient to prevent the oil-cooled electric drive system temperature from rising further (minimum cooling requirement oil pump speed). The criteria for finding these two values ​​are completely different: the former is based on power measurement and efficiency formula calculations, pursuing economic efficiency; the latter is based on temperature monitoring and thermal balance assessment, concerning safety.

[0021] Then, the final step in generating the mapping table is to compare the two key speed values ​​found above at each operating point, select the one with the larger value, and write it into the final control table.

[0022] This directly leads to the inevitable effect of the mapping table generated by this method: in the final oil pump control mapping table, the base oil pump speed set for each electric drive operating point simultaneously meets two rigid preset standards—it is neither lower than the minimum speed required to maintain the thermal safety of the system, nor does it represent the optimal (or at least superior) overall system efficiency point achievable under this safe speed constraint. This means that the oil pump control based on this mapping table inherently incorporates the principles of safety priority and efficiency optimization from the source design.

[0023] In some possible embodiments, the overall system efficiency includes the overall drive efficiency under driving conditions and the overall recovery efficiency under energy recovery conditions, wherein,

[0024] When the oil-cooled electric drive system is in driving mode, the overall driving efficiency = mechanical power / (first electric power + second electric power).

[0025] When the oil-cooled electric drive system is in energy recovery mode, the comprehensive recovery efficiency = (first electric power - second electric power) / absolute value of mechanical power.

[0026] Under driving conditions (consuming battery energy to output power), the efficiency calculation formula adds the second electrical power consumed by the oil pump as part of the total system cost to the first electrical power required for driving. The numerator is the output mechanical power. This formula measures how much electrical energy the entire system (including the drive train and cooling / lubrication auxiliary systems) needs to consume to obtain a unit of mechanical drive power. This forces the efficiency optimization process to simultaneously balance drive efficiency and auxiliary energy consumption, avoiding excessive oil pump energy consumption in pursuit of high motor efficiency.

[0027] In energy recovery mode (converting vehicle kinetic energy into electrical energy to recharge the battery), the efficiency calculation formula treats the secondary electrical power consumed by the fuel pump as a deduction from the total recovered electrical energy. The numerator is the net recovered electrical power (total recovered electrical power minus the power consumed by the fuel pump to maintain system operation), and the denominator is the absolute value of the mechanical power input to the system. This formula measures how much electrical energy can be netly recovered to the battery after deducting the auxiliary energy consumption necessary to maintain the recovery process when recovering a unit of vehicle kinetic energy. This forces the efficiency optimization process to consider the recovery benefits and maintenance costs, seeking the point where the system's net benefit is maximized.

[0028] Therefore, the direct effect of optimizing the overall efficiency using this working condition definition is that the optimal speed for efficiency will vary depending on the working condition. When driving, the focus is on minimizing the total power consumption of the system, and when recovering, the focus is on maximizing the net recovery of the system. This allows for a more accurate and complete adaptation to the vehicle's global energy efficiency optimization goals under different energy flow conditions.

[0029] In some possible embodiments, under the same operating conditions, the step of determining the minimum oil pump speed required to bring the oil-cooled electric drive system to thermal equilibrium as the minimum cooling oil pump speed for that operating condition includes:

[0030] Under the same operating conditions, the speed of the oil pump is gradually increased, and the temperature of the motor in the oil-cooled electric drive system is monitored. When the temperature of the motor reaches dynamic stability, the current oil pump speed is recorded as the minimum cooling oil pump speed under the corresponding operating conditions.

[0031] Under the premise of strictly fixed torque and speed of the oil-cooled electric drive system, the oil pump speed is treated as the only variable, and its change on the motor temperature, a key safety indicator, is observed. The minimum cooling required oil pump speed found through this method is the theoretical minimum cooling intensity required to maintain the oil-cooled electric drive system's safe and continuous operation without overheating under this specific workload (torque / speed). It is the critical threshold for ensuring the system's thermal safety under these experimental conditions. Using this value in the subsequent synthesis of the control mapping table sets an inviolable safety lower limit for the oil pump speed based on thermophysical laws, thereby fundamentally preventing the risk of overheating due to insufficient cooling in the oil-cooled electric drive system.

[0032] In some specific embodiments, the minimum oil pump speed required to meet lubrication needs is determined in the following manner:

[0033] Fabricate a prototype of an oil-cooled electric drive system with a transparent housing;

[0034] The oil-cooled electric drive system sample was mounted on a tiltable test bench, and the test bench was controlled to simulate the maximum design tilt angle of the vehicle in each direction.

[0035] At the maximum design tilt angle, the minimum oil pump speed that can ensure adequate lubrication inside the oil-cooled electric drive system sample was tested and determined.

[0036] First, by fabricating a prototype of the oil-cooled electric drive system with a transparent housing, a condition was created that allowed for direct observation of the internal lubricant flow. Next, the prototype was mounted on a tiltable test bench, and its orientation was fixed at the maximum design tilt angle allowed by the vehicle design in all directions. This step simulated the most detrimental extreme static postures that the vehicle might encounter for the lubrication system (such as uphill, downhill, and side-slope parking).

[0037] Under this most stringent fixed orientation, the minimum oil pump speed required to ensure adequate lubrication inside the oil-cooled electric drive system sample was determined through testing. Essentially, this step aimed to find a critical value: at this maximum tilt angle, if the oil pump speed is below this value, at least one critical friction pair (such as bearings or gear meshing points) will show poor lubrication (e.g., insufficient oil supply, inadequate splashing) visible through the transparent housing; while when the oil pump speed reaches or exceeds this value, all parts requiring lubrication will be observed to be fully covered by oil.

[0038] Therefore, the minimum oil pump speed calibrated using this method to meet lubrication requirements provides a safe and reliable lower limit benchmark based on direct observation and verification, ensuring that the internal mechanical components of the oil-cooled electric drive system do not experience dry friction or insufficient lubrication when the vehicle is in an extremely tilted position. Using this benchmark value in actual vehicle control can effectively prevent the risk of mechanical wear or damage caused by uneven lubrication distribution due to vehicle tilt.

[0039] In some possible embodiments, the method further includes:

[0040] During vehicle operation, the motor temperature in the oil-cooled electric drive system is monitored in real time.

[0041] When the temperature of the motor exceeds the corresponding first preset reference temperature threshold, a preset speed value is added to the target control speed as the final oil pump speed; when the temperature of the motor exceeds the corresponding second preset reference temperature threshold, the oil pump is controlled to stop and a fault is reported.

[0042] The first preset reference temperature threshold is less than the second preset reference temperature threshold.

[0043] When the real-time monitored motor temperature first exceeds the first, lower threshold value (the first preset reference temperature threshold), the protection mechanism is triggered. At this point, instead of immediately taking extreme measures, a fixed preset speed value is added to the currently calculated target control speed to improve the oil pump's cooling capacity. The direct effect of this step is that when the system first shows signs of abnormal temperature rise, it immediately intervenes by increasing the cooling intensity, attempting to suppress the temperature rise and bring it back to the normal range, thus providing the system with an opportunity for self-recovery.

[0044] If the above interventions fail and the motor temperature continues to rise and exceeds the second, higher threshold (the second preset reference temperature threshold), it indicates that the abnormal situation has worsened or that there is a more serious system fault. At this point, the protection mechanism will perform a higher-level action: controlling the oil pump to stop operating and reporting the fault. The direct effect of this step is: when the risk of system overheating exceeds the range that can be controlled by enhanced cooling, the energy consumption of the oil pump is immediately cut off, and a clear fault signal is issued. Its primary purpose is to prevent permanent hardware damage (such as demagnetization of permanent magnets, insulation layer damage) or safety accidents that may be caused by continuous overheating, while simultaneously notifying the driver or maintenance system for handling.

[0045] In summary, by introducing a graded protection mechanism, a dynamic safety redundancy layer is added to the oil pump control. This not only attempts automatic correction when the temperature slightly exceeds the limit to avoid unnecessary downtime, but also decisively executes protection measures when the temperature is severely abnormal. Thus, under abnormal operating conditions, a graded and reasonable balance is achieved between system availability (attempting to maintain operation) and system safety (decisive shutdown protection), improving the fault tolerance and operational robustness of the entire oil-cooled electric drive system against sudden thermal risks.

[0046] In some specific embodiments, the first preset reference temperature threshold and the second preset reference temperature threshold are determined based on the current operating torque and current speed of the oil-cooled electric drive system.

[0047] In some possible embodiments, the method further includes:

[0048] Monitor the actual motor temperature rise rate of the oil-cooled electric drive system;

[0049] The actual motor temperature rise rate is compared with the calibrated temperature rise rate to determine the oil quantity status of the oil-cooled electric drive system.

[0050] The calibrated temperature rise rate characteristics include: the motor temperature rise rate characteristics of the oil-cooled electric drive system when operating under standard oil quantity and various abnormal oil quantity conditions.

[0051] Firstly, a calibration temperature rise rate characteristic is required during the calibration phase. This set of characteristic data records the normal temperature rise rate of the motor when the oil-cooled electric drive system is in a standard oil quantity state under specific operating conditions. It also records the different temperature rise rates exhibited by the motor when the system is in various abnormal oil quantity states, such as insufficient or excessive oil quantity, under the same specific operating conditions. This constructs a database mapping the relationship from oil quantity state to temperature rise rate characteristics.

[0052] During actual vehicle operation, the actual motor temperature rise rate of the oil-cooled electric drive system is monitored, and this actual motor temperature rise rate is compared with the calibrated temperature rise rate characteristics. Through this comparison process, the real-time observed thermal response (temperature rise rate) is matched and searched against the thermal response-oil quantity relationship database established during the calibration phase.

[0053] This allows for the non-invasive inference and identification of potential oil level anomalies within the system (such as insufficient oil due to leakage or excessive oil due to accidental filling) by analyzing the rate of temperature rise of the motor during operation, utilizing the inherent thermal characteristics of the oil-cooled electric drive system. It enables effective monitoring and early warning of the oil cooling circuit's health status without the need for additional oil level sensors.

[0054] Secondly, this application also provides a controller, including:

[0055] The parameter acquisition module is used to acquire the vehicle's current tilt angle, the current operating torque of the oil-cooled electric drive system, and the current speed.

[0056] The base oil pump speed determination module is used to determine the base oil pump speed corresponding to the current operating torque and the current speed based on a preset oil pump control mapping table. The oil pump control mapping table is generated in the following way: for multiple oil-cooled electric drive system operating points, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system.

[0057] The lubricating oil pump speed determination module is used to determine the minimum oil pump speed that meets the lubrication requirements based on the current tilt angle.

[0058] The oil pump target speed determination module is used to compare the base oil pump speed with the minimum oil pump speed that meets the lubrication requirements, and select the larger value as the target control speed of the oil pump.

[0059] Thirdly, this application also provides a vehicle including the aforementioned controller. Attached Figure Description

[0060] Figure 1 This is a structural block diagram of the vehicle in the embodiments of this application;

[0061] Figure 2 This is a flowchart illustrating the oil-cooled electric drive oil pump control method in the embodiments of this application;

[0062] Figure 3 This is a schematic diagram of the test bench in the embodiments of this application;

[0063] Figure 4 This is a flowchart illustrating the calibration method for an oil-cooled electrically driven oil pump in an embodiment of this application. Detailed Implementation

[0064] Reference Figure 1 This application provides a vehicle 100, which includes a power battery 11, a low-voltage storage battery 12, an oil-cooled electric drive system 13, an oil pump 14, and a reducer 15. The oil pump and oil-cooled electric drive system 13 includes an electronic control unit 131 and a motor 132.

[0065] The vehicle 10 can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), a new energy vehicle, or a fuel vehicle.

[0066] The power battery 11 is electrically connected to the high-voltage control unit 131 to provide high-voltage drive power for the control unit 131 and the motor 132. The low-voltage battery 12 is electrically connected to the oil pump 14 and the low-voltage control section of the control unit 131 to power the operation of the oil pump 14 and the control logic of the control unit 131. The control unit 131 is electrically connected to the motor 132 to receive control commands and drive the motor 132 to operate, or to process the electrical energy generated by the motor 132 during energy recovery. The output shaft of the motor 132 is mechanically connected to the reducer 15 to transmit the torque and speed output by the motor 132 to the vehicle wheels after adjustment by the reducer 15. The oil pump 14 is connected to the cooling and lubrication circuit of the oil-cooled electric drive system 13 through an oil circuit to pump oil to the motor 132 and the reducer 15 under the control of the control unit 131, thereby cooling the motor 132 (stator and rotor) and lubricating the bearings of the motor 132 and the gears of the reducer 15.

[0067] The vehicle 100 also includes a controller (not shown in the figure), which is connected to the electronic control unit 131, the oil pump 14, and vehicle attitude sensors (such as gyroscopes). The controller includes: a parameter acquisition module for acquiring the vehicle's current tilt angle, the current operating torque of the oil-cooled electric drive system, and the current speed; a base oil pump speed determination module for determining the base oil pump speed corresponding to the current operating torque and current speed based on a preset oil pump control mapping table; wherein, the oil pump control mapping table is generated in the following manner: for multiple operating points of the oil-cooled electric drive system, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system; a lubricating oil pump speed determination module for determining the minimum oil pump speed that meets the lubrication requirements based on the current tilt angle; and an oil pump target speed determination module for comparing the base oil pump speed with the minimum oil pump speed that meets the lubrication requirements and selecting the larger value as the target control speed of the oil pump.

[0068] The controller obtains the current tilt angle in real time by reading angle signals from vehicle attitude sensors (such as gyroscopes) via the CAN bus. Simultaneously, the controller acquires the real-time rotational speed signal of the motor rotor from the motor controller and calculates or directly receives the actual output torque value reported by the motor controller based on the motor phase current and magnetic field model. Here, the current operating torque and current rotational speed of the oil-cooled electric drive system specifically refer to the real-time mechanical output state at the motor shaft end.

[0069] The controller internally stores a three-dimensional lookup table (oil pump control mapping table), where the horizontal and vertical axes represent torque and speed, respectively. The table values ​​are the optimized and calibrated base oil pump speeds. The controller uses real-time acquired current operating torque and current speed to interpolate and retrieve the corresponding base oil pump speed from this table.

[0070] The controller stores a table showing the relationship between the vehicle's tilt angle and the minimum lubrication speed (usually a simple linear or piecewise function verified on a bench). Based on the real-time tilt angle, the minimum oil pump speed required to ensure adequate lubrication to all lubrication points at that tilt angle is obtained by looking up the table or by calculation.

[0071] The controller performs a numerical comparison calculation within each control cycle, selecting the larger value from the obtained base oil pump speed and the obtained minimum oil pump speed that meets lubrication requirements. This larger value is then used as the target oil pump speed corresponding to the PWM duty cycle command ultimately sent to the oil pump driver. This "larger value" logic is essentially an optimal arbitration mechanism under multiple constraints, ensuring that the final target control speed always simultaneously meets three core requirements: system-level energy efficiency optimization, motor thermal safety, and mechanical lubrication safety. Through this design, the most suitable cooling and lubrication intensity can be automatically selected under various operating conditions, achieving global energy consumption minimization under safety constraints.

[0072] In this embodiment of the application, the controller further includes:

[0073] The motor temperature detection module is used to monitor the motor temperature in the oil-cooled electric drive system in real time during vehicle operation.

[0074] The speed compensation module is used to add a preset speed value to the target control speed as the final oil pump speed when the temperature of the motor exceeds the corresponding first preset reference temperature threshold; and to control the oil pump to stop and report the fault when the temperature of the motor exceeds the corresponding second preset reference temperature threshold.

[0075] The first preset reference temperature threshold is less than the second preset reference temperature threshold.

[0076] The controller obtains the motor's current operating temperature by receiving real-time signals from temperature sensors (such as PT100 or thermistors) embedded in the motor stator windings, with a fixed sampling period (e.g., 10 milliseconds). Here, the motor temperature specifically refers to the temperature of the stator windings, which are most sensitive to overheating. By directly and continuously measuring the temperature of the motor's core heat-generating components, a crucial monitoring channel for the thermal state of the oil-cooled electric drive system is established.

[0077] The controller compares the real-time monitored motor temperature with a pre-calibrated first preset reference temperature threshold (T_warn), which is typically set slightly higher than the steady-state equilibrium temperature calibrated on the test bench under the corresponding operating conditions. Once the monitored temperature exceeds the first preset reference temperature threshold T_warn, the controller immediately adds a fixed preset speed increment (ΔN) to the target control speed calculated by the main control logic (as described in steps S1-S4 above), and sends this added speed as the final oil pump speed to the oil pump. For example, if the target control speed is 2000 rpm and ΔN is 500 rpm, then the final oil pump speed is 2500 rpm.

[0078] The second preset reference temperature threshold (T_fault) is close to the limit tolerance temperature of the motor insulation material or the critical temperature that may cause demagnetization of the permanent magnet. If the first-level protection fails to suppress the temperature rise, causing the temperature to continue to rise and exceed T_fault, the controller will immediately issue a stop command to the oil pump driver, forcing the oil pump to stop operating, and at the same time report the abnormal over-temperature fault code (DTC) of the motor to the instrument panel or remote monitoring platform through the vehicle diagnostic system (such as UDS protocol).

[0079] This two-tiered protection mechanism achieves an optimal balance between safety redundancy and system availability. The first-tier protection proactively enhances cooling when temperatures slightly exceed limits, attempting to autonomously correct abnormal states without interrupting power. This avoids unnecessary performance limitations or fault alarms caused by brief thermal load fluctuations, improving driving smoothness. The second-tier protection decisively shuts down the system when thermal anomalies worsen and hardware damage risks occur, providing a final protective barrier for critical components. This prevents permanent damage caused by overheating (such as winding insulation breakdown or magnet demagnetization) and clearly informs users or maintenance systems of the fault information, ensuring safety and maintainability. The setting of a first preset reference temperature threshold T_warn < a second preset reference temperature threshold T_fault establishes a clear buffer between warnings and fatal faults.

[0080] In this embodiment, the first preset reference temperature threshold (T_warn) and the second preset reference temperature threshold (T_fault) are not fixed values, but are dynamically determined based on the current operating torque and current speed of the oil-cooled electric drive system. The controller internally stores a two-dimensional lookup table similar to the oil pump control mapping table. The horizontal and vertical axes of this table are also torque and speed, and each cell stores a calibrated pair of (T_warn, T_fault) thresholds corresponding to that operating condition.

[0081] Because the thermal equilibrium temperature, heat capacity, and heat dissipation requirements of an electric motor differ under different loads (torque) and speeds. For example, at high torque and low speed (such as when climbing a hill), the motor current is high and the heat generation is high, but the heat dissipation capacity provided by the fan (if air-cooled) or oil pump flow rate may be insufficient, resulting in a higher steady-state temperature. Conversely, at high speed and low torque (such as during high-speed cruising), air cooling may be enhanced or oil circuit circulation may be faster, leading to better heat dissipation. Therefore, during the bench calibration phase, at each test operating point (specific torque and speed), not only are the optimal efficiency speed and the speed requiring cooling recorded, but also the reasonable warning temperature T_warn (such as slightly higher than the steady-state equilibrium temperature of that operating condition) and the extreme safety temperature T_fault are determined experimentally for that operating condition. During actual vehicle operation, after obtaining the current operating torque and speed, the controller synchronously queries this threshold mapping table to obtain the applicable, personalized temperature protection threshold for the current operating condition.

[0082] In this embodiment of the application, the controller further includes:

[0083] Temperature rise rate detection module is used to monitor the actual motor temperature rise rate of the oil-cooled electric drive system;

[0084] The oil level status judgment module is used to compare the actual motor temperature rise rate with the calibrated temperature rise rate characteristics to determine the oil level status of the oil-cooled electric drive system.

[0085] The calibrated temperature rise rate characteristics include: the motor temperature rise rate characteristics of the oil-cooled electric drive system when operating under standard oil quantity and various abnormal oil quantity conditions.

[0086] The controller calculates the rate of temperature rise per unit time, or temperature rise rate (unit: °C / s or °C / min), by collecting the motor temperature signal in real time. Specifically, the controller obtains the difference between the current temperature and the temperature of the previous cycle at a fixed calculation period (e.g., every 10 seconds), and then divides it by the time interval to obtain the average temperature rise rate. To improve accuracy, monitoring is usually performed under selected typical steady-state or quasi-steady-state operating conditions. For example, after the oil-cooled electric drive system 13 has been running at a certain constant torque and speed for a period of time, the heat generation and heat dissipation are mainly affected by the system's own characteristics, excluding the interference of drastic transient changes.

[0087] The controller has a pre-stored database of calibrated temperature rise rate characteristics under different standard operating conditions. This database is established through prior bench calibration: on the bench, the electric drive system is controlled to run a series of typical operating conditions under various known oil quantity states, such as standard oil quantity, insufficient oil quantity, and excessive oil quantity, and the stable motor temperature rise rate under each state and each operating condition is accurately recorded, thereby forming characteristic curves or characteristic value mappings.

[0088] During actual vehicle operation, when the vehicle enters a typical operating condition that matches the calibration data, the controller compares the currently calculated actual motor temperature rise rate with the nominal temperature rise rate characteristic corresponding to the standard oil quantity under that operating condition in the database. If the actual rate is significantly higher than the nominal value (e.g., exceeding the preset deviation range), it may be inferred that there is insufficient oil quantity leading to inadequate cooling / lubrication and reduced heat dissipation capacity; if the actual rate is abnormally low (under specific operating conditions), it may indicate abnormal conditions such as excessive oil quantity leading to abnormally increased oil churning loss and excessively rapid oil temperature rise, indirectly affecting heat dissipation efficiency.

[0089] In this embodiment of the application, the generation of the oil pump control mapping table includes:

[0090] In bench testing, various combinations of electric drive torque and electric drive speed were tested, and the following procedures were performed:

[0091] The mechanical power of the oil-cooled electric drive system, the first electrical power input to the oil-cooled electric drive system, and the second electrical power input to the oil pump were tested at different oil pump speeds.

[0092] Calculate the overall system efficiency at different oil pump speeds based on the mechanical power, the first electrical power, and the second electrical power.

[0093] The oil pump speed that maximizes the overall efficiency of the system is selected as the optimal speed for this combined operating condition.

[0094] Under the same operating conditions, the minimum oil pump speed that enables the oil-cooled electric drive system to reach thermal equilibrium is determined as the minimum cooling oil pump speed for that operating condition.

[0095] For each operating condition combination, the larger of the optimal efficiency speed and the minimum cooling requirement oil pump speed is taken as the base oil pump speed in the oil pump control mapping table for that operating condition.

[0096] The overall system efficiency includes the overall drive efficiency under driving conditions and the overall recovery efficiency under energy recovery conditions.

[0097] When the oil-cooled electric drive system is in driving mode, the overall driving efficiency = mechanical power / (first electric power + second electric power).

[0098] When the oil-cooled electric drive system is in energy recovery mode, the comprehensive recovery efficiency = (first electric power - second electric power) / absolute value of mechanical power.

[0099] Under the same operating conditions, the steps for determining the minimum oil pump speed required to achieve thermal equilibrium in the oil-cooled electric drive system as the minimum cooling oil pump speed for that operating condition include:

[0100] Under the same operating conditions, the speed of the oil pump is gradually increased, and the temperature of the motor in the oil-cooled electric drive system is monitored. When the temperature of the motor reaches dynamic stability, the current oil pump speed is recorded as the minimum cooling oil pump speed under the corresponding operating conditions.

[0101] The minimum oil pump speed required to meet lubrication needs is determined by the following method:

[0102] Fabricate a prototype of an oil-cooled electric drive system with a transparent housing;

[0103] The oil-cooled electric drive system sample was mounted on a tiltable test bench, and the test bench was controlled to simulate the maximum design tilt angle of the vehicle in each direction.

[0104] At the maximum design tilt angle, the minimum oil pump speed that can ensure adequate lubrication inside the oil-cooled electric drive system sample was tested and determined.

[0105] In this embodiment, the above-mentioned oil pump control mapping table is obtained by the following oil-cooled electric drive oil pump calibration method that takes into account the oil pump energy consumption. This oil pump electric drive oil pump calibration method comprehensively considers the energy consumption of oil pump 14 and oil-cooled electric drive system 13, while also taking into account the cooling and lubrication requirements of oil-cooled electric drive system 13, so that the overall matching efficiency of oil pump 14 and oil-cooled electric drive system 13 reaches the optimal level, thereby reducing the energy consumption of the whole vehicle and improving the economy of the whole vehicle.

[0106] Reference Figure 4 The calibration method for this oil-cooled electric drive oil pump is as follows:

[0107] S100: Construct a test bench, such as Figure 3 The modules or components involved in the test bench system include: dynamometer, high-voltage power supply cabinet, oil-cooled electric drive system (including electronic control and motor), oil pump, low-voltage power supply, simulated vehicle computer, first power analyzer, second power analyzer, and dynamometer.

[0108] The first power analyzer collects the bus voltage and current of the input oil-cooled electric drive system; the second power analyzer collects the voltage and current of the oil pump; the low-voltage power supply connects to the oil pump and the electronic control unit to supply power to both; the output end of the electric drive is connected to the dynamometer through the reducer, so that the dynamometer can measure the output torque of the electric drive; the high-voltage power supply cabinet provides high-voltage power to the electronic control unit.

[0109] It should be further noted that the names of the components on this test bench are for illustrative purposes only. Any other component with the same or similar functions can be used as a substitute, and the relevant signals monitored by the component itself with similar functions can also be substituted.

[0110] S101: Simulates the vehicle's computer, controlling the torque of the oil-cooled electric drive system from 0, ±5N, ±10N, ±15N, ... ±maximum torque, increasing sequentially. The speed of the oil-cooled electric drive system increases sequentially from 0 rpm, 500 rpm, 1000 rpm, 1500 rpm, ... maximum speed. At the same torque and speed, the oil pump speed increases sequentially from 500 rpm, 1000 rpm, 1500 rpm, ... maximum speed. A dynamometer measures the mechanical power, a first power analyzer measures the first electrical power input to the oil-cooled electric drive system, and a second power analyzer measures the second electrical power input to the oil pump.

[0111] S102: Calculate the overall system efficiency at different oil pump speeds when the oil-cooled electric drive system is working. Based on the data measured in S101, the calculation method is as follows: select the oil pump speed with the best overall system efficiency as the numerical sequence 1.

[0112] Overall drive efficiency = Mechanical power / (Electric drive power + Oil pump power)

[0113] Overall recovery efficiency = (electric drive power - oil pump power) / mechanical power.

[0114] Specifically, simulating the vehicle's computer, the torque of the oil-cooled electric drive system is controlled to increase sequentially from 0, ±5N, ±10N, ±15N, ... ±maximum torque. The speed of the oil-cooled electric drive system is controlled to increase sequentially from 0 rpm, 500 rpm, 1000 rpm, 1500 rpm, ... to the maximum speed. Under the same torque and speed conditions, the oil pump speed is controlled to increase sequentially from 500 rpm, 1000 rpm, 1500 rpm, ... to the maximum speed. A dynamometer measures the mechanical power, a first power analyzer measures the first electrical power input to the oil-cooled electric drive system, and a second power analyzer measures the second electrical power input to the oil pump. It should be noted that the torque-speed interval of the oil-cooled electric drive system and the oil pump speed interval are not unique; this is only an example. In practice, a smaller interval results in more accurate data and more precise control.

[0115] S103: Based on the data points of S102, the data points can be densified to form data network 1 through interpolation, fitting and other methods, so that the data density of the relationship between oil pump speed and electric drive power and torque meets the response requirements of the whole vehicle.

[0116] S104: By observing the stator and rotor temperatures of the motor monitored by the motor controller, the oil pump speed is gradually increased at the same torque and speed until the stator and rotor temperatures of the motor are constant. This yields the oil pump speed with the lowest cooling requirement at the motor torque and speed, forming numerical sequence 2. Similarly, data network 2 is formed in the same way as in S103.

[0117] S105: Based on the tilt angle requirements of various companies' vehicles (front, rear, left, and right), fabricate transparent reducer and motor housing electric drive samples for observation of the lubrication inside the electric drive. Figure 3 A test bench was built, and an overall tilting device was added to the test bench. The minimum speed n1 of the electric drive lubrication oil pump was tested at the maximum tilt angle in each direction.

[0118] S106: Compare the oil pump speed data of data network 2 and data network 1, replace the value in data network 1 with the oil pump speed in data network 2 which is greater than the oil pump speed in data network 1, form a new data network 3 as shown in Table 1, and write data network 3 into the vehicle's oil pump control system.

[0119]

[0120] Table 1

[0121] S107: Based on the vehicle tilt angle identified by the vehicle gyroscope and the vehicle speed and torque requirements, compare the oil pump speed n1 corresponding to the minimum lubrication requirement at the vehicle tilt angle with the corresponding oil pump speed in data network 3. If n1 is larger, take n1; if n1 is smaller, take the oil pump speed in data network 3. This can be used as the basic control of the oil pump based on the optimization of vehicle energy consumption.

[0122] S108: Based on the above control, for a more secure consideration, a motor redundancy protection calibration can be added. When the motor stator temperature is balanced with the oil pump speed during bench testing, the motor stator temperature t is recorded. When the vehicle is running, the motor stator temperature is monitored. At the corresponding speed and torque, if the motor stator temperature exceeds the bench-recorded temperature t1℃, the oil pump speed is appropriately increased by N revolutions for compensation. If the motor stator temperature continues to increase and exceeds t2℃, the oil pump is controlled to stop and an abnormal over-temperature fault of the motor is reported.

[0123] S109: Going a step further, based on the issues of insufficient or excessive oiling in factories and after-sales service, typical working conditions can be selected, and the temperature rise gradient of the motor stator under various oiling conditions can be calibrated on the test bench. Based on different temperature gradients, the oiling situation can be judged to protect the oil-cooled electric drive system.

[0124] Reference Figure 2 This application also provides a method for controlling an oil-cooled electrically driven oil pump, including:

[0125] S1, obtain the vehicle's current tilt angle, the current operating torque of the oil-cooled electric drive system, and the current speed;

[0126] S2, based on a preset oil pump control mapping table, determine the base oil pump speed corresponding to the current working torque and the current speed; wherein, the oil pump control mapping table is generated in the following way: for multiple oil-cooled electric drive system operating points, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system;

[0127] S3, Based on the current tilt angle, determine the minimum oil pump speed that meets the lubrication requirements;

[0128] S4. The base oil pump speed is compared with the minimum oil pump speed that meets the lubrication requirements, and the larger value is selected as the target control speed of the oil pump.

[0129] In some embodiments, the method further includes:

[0130] S5, During vehicle operation, monitor the motor temperature in the oil-cooled electric drive system in real time;

[0131] S6, when the temperature of the motor exceeds the corresponding first preset reference temperature threshold, a preset speed value is added to the target control speed as the final oil pump speed; when the temperature of the motor exceeds the corresponding second preset reference temperature threshold, the oil pump is controlled to stop and a fault is reported.

[0132] The first preset reference temperature threshold is less than the second preset reference temperature threshold.

[0133] In some embodiments, the method further includes:

[0134] S7 monitors the actual motor temperature rise rate of the oil-cooled electric drive system;

[0135] S8, compare the actual motor temperature rise rate with the calibrated temperature rise rate characteristic to determine the oil quantity status of the oil-cooled electric drive system;

[0136] The calibrated temperature rise rate characteristics include: the motor temperature rise rate characteristics of the oil-cooled electric drive system when operating under standard oil quantity and various abnormal oil quantity conditions.

[0137] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. A control method for an oil-cooled electrically driven oil pump, characterized in that, include: Obtain the vehicle's current tilt angle, the current operating torque of the oil-cooled electric drive system, and the current speed; Based on a preset oil pump control mapping table, a base oil pump speed corresponding to the current operating torque and current speed is determined; wherein, the oil pump control mapping table is generated in the following way: for multiple oil-cooled electric drive system operating points, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system. Based on the current tilt angle, determine the minimum oil pump speed that meets the lubrication requirements; The base oil pump speed is compared with the minimum oil pump speed required to meet lubrication needs, and the larger value is selected as the target control speed of the oil pump.

2. The oil-cooled electric drive oil pump control method according to claim 1, characterized in that, The generation of the oil pump control mapping table includes: In bench testing, various combinations of electric drive torque and electric drive speed were tested, and the following procedures were performed: The mechanical power of the oil-cooled electric drive system, the first electrical power input to the oil-cooled electric drive system, and the second electrical power input to the oil pump were tested at different oil pump speeds. Calculate the overall system efficiency at different oil pump speeds based on the mechanical power, the first electrical power, and the second electrical power. The oil pump speed that maximizes the overall efficiency of the system is selected as the optimal speed for this combined operating condition. Under the same operating conditions, the minimum oil pump speed that enables the oil-cooled electric drive system to reach thermal equilibrium is determined as the minimum cooling oil pump speed for that operating condition. For each operating condition combination, the larger of the optimal efficiency speed and the minimum cooling requirement oil pump speed is taken as the base oil pump speed in the oil pump control mapping table for that operating condition.

3. The oil-cooled electric drive oil pump control method according to claim 2, characterized in that, The overall system efficiency includes the overall drive efficiency under driving conditions and the overall recovery efficiency under energy recovery conditions, wherein... When the oil-cooled electric drive system is in driving mode, the overall driving efficiency = mechanical power / (first electric power + second electric power). When the oil-cooled electric drive system is in energy recovery mode, the comprehensive recovery efficiency = (first electric power - second electric power) / absolute value of mechanical power.

4. The oil-cooled electric drive oil pump control method according to claim 2, characterized in that, Under the same operating conditions, the steps for determining the minimum oil pump speed required to achieve thermal equilibrium in the oil-cooled electric drive system as the minimum cooling oil pump speed for that operating condition include: Under the same operating conditions, the speed of the oil pump is gradually increased, and the temperature of the motor in the oil-cooled electric drive system is monitored. When the temperature of the motor reaches dynamic stability, the current oil pump speed is recorded as the minimum cooling oil pump speed under the corresponding operating conditions.

5. The oil-cooled electric drive oil pump control method according to claim 1, characterized in that, The minimum oil pump speed required to meet lubrication needs is determined by the following method: Fabricate a prototype of an oil-cooled electric drive system with a transparent housing; The oil-cooled electric drive system sample was mounted on a tiltable test bench, and the test bench was controlled to simulate the maximum design tilt angle of the vehicle in each direction. At the maximum design tilt angle, the minimum oil pump speed that can ensure adequate lubrication inside the oil-cooled electric drive system sample was tested and determined.

6. The oil-cooled electric drive oil pump control method according to claim 1, characterized in that, The method further includes: During vehicle operation, the motor temperature in the oil-cooled electric drive system is monitored in real time. When the temperature of the motor exceeds the corresponding first preset reference temperature threshold, a preset speed value is added to the target control speed as the final oil pump speed; when the temperature of the motor exceeds the corresponding second preset reference temperature threshold, the oil pump is controlled to stop and a fault is reported. The first preset reference temperature threshold is less than the second preset reference temperature threshold.

7. The oil-cooled electric drive oil pump control method according to claim 1, characterized in that, The first preset reference temperature threshold and the second preset reference temperature threshold are determined based on the current operating torque and current speed of the oil-cooled electric drive system.

8. The oil-cooled electric drive oil pump control method according to claim 1, characterized in that, The method further includes: Monitor the actual motor temperature rise rate of the oil-cooled electric drive system; The actual motor temperature rise rate is compared with the calibrated temperature rise rate to determine the oil quantity status of the oil-cooled electric drive system. The calibrated temperature rise rate characteristics include: the motor temperature rise rate characteristics of the oil-cooled electric drive system when operating under standard oil quantity and various abnormal oil quantity conditions.

9. A controller, characterized in that, include: The parameter acquisition module is used to acquire the vehicle's current tilt angle, the current operating torque of the oil-cooled electric drive system, and the current speed. The base oil pump speed determination module is used to determine the base oil pump speed corresponding to the current operating torque and the current speed based on a preset oil pump control mapping table. The oil pump control mapping table is generated in the following way: for multiple oil-cooled electric drive system operating points, the oil pump speed that optimizes the overall working efficiency of the oil-cooled electric drive system and the oil pump is used as the initial reference, and the initial reference is corrected by a higher oil pump speed that meets the minimum cooling requirements of the oil-cooled electric drive system. The lubricating oil pump speed determination module is used to determine the minimum oil pump speed that meets the lubrication requirements based on the current tilt angle. The oil pump target speed determination module is used to compare the base oil pump speed with the minimum oil pump speed that meets the lubrication requirements, and select the larger value as the target control speed of the oil pump.

10. A vehicle, characterized in that, Includes the controller as described in claim 9.

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