Search

CN-121997443-A - Method, device, system and medium for estimating oil temperature of electric drive system

CN121997443ACN 121997443 ACN121997443 ACN 121997443ACN-121997443-A

Abstract

The application provides an oil temperature estimation method, device, system and medium of an electric drive system, wherein the method comprises the following steps: and calculating to obtain the current moment oil temperature according to one of the oil density, the oil specific heat capacity, the time from the starting of the vehicle to the current moment of operation of the vehicle, the moment oil temperature on the vehicle electric drive system, the second heat productivity and the third heat dissipation capacity, and the fourth heat dissipation capacity or the fifth heat dissipation capacity. According to the application, a mode of acquiring the oil temperature by using the oil temperature sensor, the oil pump and a corresponding power circuit and detection circuit in the prior art is omitted, the structure of the oil temperature detection system is simplified, the application requirements of water cooling and oil cooling electric drive are met, the oil temperature can be accurately acquired by using an oil temperature estimation method, the cost and the failure rate of hardware are reduced, and the robustness is improved.

Inventors

  • ZHUANG ZHENYA
  • LI RUI
  • WANG JIAN

Assignees

  • 上海汽车集团股份有限公司

Dates

Publication Date
20260508
Application Date
20241101

Claims (10)

  1. 1. An electric drive system oil temperature estimation method is characterized by comprising the following steps: Acquiring the oil temperature at the last moment of a vehicle electric drive system; according to the first preset dimensionless coefficient, the current moment motor torque and the current moment motor rotating speed, calculating to obtain the first heating value of the reduction gearbox at the current moment and the second heating value of the motor; according to a second preset dimensionless coefficient, the motor rotating speed at the current moment, the oil temperature at the last moment of the vehicle electric drive system and the air temperature outside the vehicle at the current moment, calculating to obtain a third heat dissipation capacity of the oil passing through the electric drive shell and the air at the current moment; If the vehicle is a water-cooling electric drive, calculating to obtain fourth heat dissipation quantity of oil liquid at the current moment through heat exchange of an electric drive shell and cooling liquid according to a third preset dimensionless coefficient, the oil temperature at the last moment of the vehicle electric drive system, the temperature of the cooling liquid flowing through the water-cooling electric drive at the current moment and the flow of the cooling liquid flowing through the water-cooling electric drive at the current moment; if the vehicle is an oil-cooled electric drive, calculating to obtain a fifth heat dissipating capacity of the oil liquid at the current moment through heat exchange of the oil cooler and the cooling liquid according to a fourth preset dimensionless coefficient, the oil temperature at the last moment of the vehicle electric drive system, the temperature of the cooling liquid flowing through the water-cooled electric drive at the current moment, the flow rate of the cooling liquid flowing through the water-cooled electric drive at the current moment and the rotation speed of the oil pump at the current moment; And calculating to obtain the current moment oil temperature according to one of the oil density, the oil specific heat capacity, the time from the starting of the vehicle to the running of the vehicle at the current moment, the last moment oil temperature of the vehicle electric drive system, the second heating value and the third heat dissipation value, and the fourth heat dissipation value or the fifth heat dissipation value.
  2. 2. The method of claim 1, further comprising calculating an initial oil temperature at the start of the present vehicle based on an initial preset dimensionless coefficient, a motor temperature at the end of the last driving flameout, a motor temperature at the start of the present vehicle, an outside air temperature at the present time, and an oil temperature at the end of the last driving flameout, specifically by the following formula: Wherein, T oil@t＝0 is the initial oil temperature, k 0 is the initial preset dimensionless coefficient, T #otor@t＝0 is the motor temperature when the vehicle is started, T $otor@t＝N is the motor temperature when the last driving is finished and flameout, T alr is the air temperature outside the vehicle at the current moment, and T oil@t＝N is the oil temperature when the last driving is finished and flameout.
  3. 3. The method according to claim 2, wherein the third heat dissipation amount of the oil passing through the electric driving housing and the air at the current time is calculated according to the second preset dimensionless coefficient, the motor rotation speed at the current time, the oil temperature at the last time of the electric driving system of the vehicle and the air temperature outside the vehicle at the current time, specifically by the following formula: Q 3 ＝-k 2 N speed c (T oil@t＝n-1 -T air ) d ; Wherein T oil@t＝n-1 is the oil temperature at the previous time of the vehicle electric drive system, Q 3 is the third heat dissipation capacity, and k 2 , c and d are the second preset dimensionless coefficients.
  4. 4. The method according to claim 3, wherein if the vehicle is an oil-cooled electric drive, a fifth heat dissipation capacity of heat exchange between the oil liquid at the current time through the oil cooler and the cooling liquid is calculated according to a fourth preset dimensionless coefficient, an oil temperature at the last time of the vehicle electric drive system, a temperature of the cooling liquid flowing through the water-cooled electric drive at the current time, a flow rate of the cooling liquid flowing through the water-cooled electric drive at the current time and an oil pump rotation speed at the current time, specifically by the following formula: Q 5 ＝-k 4 (T oil@t＝n-1 -T clnt )fn g q clnt h ; Wherein Q 5 is the fifth heat dissipation capacity, k 4 , f, g and h are the fourth preset dimensionless coefficients, T clnt is the temperature of the cooling liquid flowing through the water-cooled electric drive at the current moment, n is the rotational speed of the oil pump at the current moment, and qcl n T is the flow rate of the cooling liquid flowing through the water-cooled electric drive at the current moment.
  5. 5. An electric drive system oil temperature estimation device, characterized by comprising: The acquisition unit is used for acquiring the oil temperature at the last moment of the vehicle electric drive system; The second calculation unit is used for calculating and obtaining the first heating value of the reduction gearbox at the current moment and the second heating value of the motor according to the first preset dimensionless coefficient, the motor torque at the current moment and the motor rotating speed at the current moment; The third calculation unit is used for calculating and obtaining third heat dissipation capacity of the oil liquid passing through the electric drive shell and the air at the current moment according to a second preset dimensionless coefficient, the motor rotating speed at the current moment, the oil temperature at the last moment of the vehicle electric drive system and the air temperature outside the vehicle at the current moment; The fourth calculation unit is used for calculating to obtain fourth heat dissipation quantity of the oil liquid at the current moment through heat exchange of the electric drive shell and the cooling liquid according to a third preset dimensionless coefficient, the oil temperature at the last moment of the electric drive system of the vehicle, the temperature of the cooling liquid flowing through the water-cooled electric drive at the current moment and the flow of the cooling liquid flowing through the water-cooled electric drive at the current moment if the vehicle is a water-cooled electric drive; A fifth calculation unit, configured to calculate, if the vehicle is an oil-cooled electric drive, a fifth heat dissipation capacity of the oil liquid at the current moment through the oil cooler and the coolant according to a fourth preset dimensionless coefficient, an oil temperature at a previous moment of the vehicle electric drive system, a coolant temperature flowing through the water-cooled electric drive at the current moment, a coolant flow flowing through the water-cooled electric drive at the current moment, and an oil pump rotation speed at the current moment; And the sixth calculation unit is used for calculating the current moment oil temperature according to one of the oil density, the oil specific heat capacity, the time from the start of the vehicle to the current moment of operation of the vehicle, the last moment oil temperature of the vehicle electric drive system, the second heating value and the third heat dissipation value, and the fourth heat dissipation value or the fifth heat dissipation value.
  6. 6. The apparatus of claim 5, further comprising a first calculation unit configured to calculate an initial oil temperature at a start of the vehicle according to the following formula: Wherein, T oil@t＝0 is the initial oil temperature, k 0 is an initial preset dimensionless coefficient, T motor@t＝0 is the motor temperature when the vehicle is started, T motor@t＝N is the motor temperature when the last driving is finished and flameout, T air is the air temperature outside the vehicle at the current moment, and T oil@t＝N is the oil temperature when the last driving is finished and flameout.
  7. 7. The apparatus of claim 6, wherein the third calculation unit is specifically configured to calculate the third heat dissipation capacity by the following formula: Q 3 ＝-k 2 N speed c (T oil@t＝n-1 -T air ) d ; Wherein T oil@t＝n-1 is the oil temperature at the previous time of the vehicle electric drive system, Q 3 is the third heat dissipation capacity, and k 2 , c and d are the second preset dimensionless coefficients.
  8. 8. The apparatus of claim 7, wherein the fifth calculation unit is specifically configured to calculate the fifth heat dissipation capacity by the following formula: Q 5 ＝-k 4 (T oil@t＝n-1 -T clnt ) f n g q clnt h ; Wherein Q 5 is the fifth heat dissipation capacity, k 4 , f, g and h are the fourth preset dimensionless coefficients, T clnt is the temperature of the cooling liquid flowing through the water-cooled electric drive at the current moment, n is the rotational speed of the oil pump at the current moment, and Q clnt is the flow rate of the cooling liquid flowing through the water-cooled electric drive at the current moment.
  9. 9. An electric drive system oil temperature estimation system, comprising: A memory for storing a computer program; A processor for implementing the steps of the method for estimating the oil temperature of an electric drive system according to any one of claims 1 to 4 when executing said computer program.
  10. 10. A computer readable medium, characterized in that the computer readable medium has stored thereon a computer program which, when processed and executed, implements the steps of the method for estimating the oil temperature of an electric drive system according to any one of claims 1-4.

Description

Method, device, system and medium for estimating oil temperature of electric drive system Technical Field The application relates to the technical field of vehicles, in particular to an oil temperature estimation method, device, system and medium of an electric drive system. Background Transmission systems such as motors and reducers inevitably have certain abrasion in the processes of gear engagement and bearing inner rotation, and lubricating oil is generally adopted to lubricate the surfaces of the transmission components in order to reduce friction loss and protect the transmission components. In addition to reducing wear during the flow of lubricant over the surface of the component, the lubricant also removes heat. Too high or too low an oil temperature can have a major impact on the lubrication cooling effect, even if the oil itself is subject to deterioration at extremely high temperatures, thereby affecting the life of the overall lubrication system. Therefore, in the currently mainstream lubrication and cooling oil system, an oil temperature sensor is generally adopted, and an oil temperature signal is monitored in real time and fed back to an oil pump control unit or a main control unit. When the oil temperature is too high or too low, the opening degree of the oil pump or the water pump is adjusted, so that the oil temperature is adjusted to be within a temperature range suitable for the system to work. Three patents CN116502444A, CN112416030B and CN113833841a disclose oil temperature estimation models for electric drive systems. These patents are primarily directed to oil-cooled electric drive systems in which the oil temperature is estimated by the operating state of an oil pump in the oil-cooled system. The basic idea of the oil temperature estimation model in CN116502444A is that the oil pump rotating speed is obtained in real time, when the oil pump rotating speed is less than a preset threshold value, the oil temperature at the current moment is obtained through the motor temperature and the oil temperature estimation at the last moment, and when the oil pump rotating speed is more than or equal to the preset threshold value, the oil temperature at the current moment is obtained through the rotating speed, the current, the voltage and the flow resistance characteristics of an oil way of the oil pump. CN112416030B discloses an oil temperature estimation method based on the electrical characteristics of the present motor, and the oil temperature at the present moment is calculated by the rotation speed and current of the oil pump and the mapping relation between these variables and the oil temperature. CN113833841a describes an oil temperature estimation model, which measures the current value of the oil temperature at a reference rotational speed, and queries a correspondence table of the current-rotational speed-oil temperature, thereby calculating the oil temperature of the transmission. The above patent is mainly applied to an oil-cooled electric drive system, and the oil temperature of the electric drive system is estimated according to the electric characteristics of a motor of an oil pump. There are two problems: 1. And 2, under the condition of oil pump failure, the oil temperature of the electric drive system cannot be estimated, so that the parts cannot be protected. Therefore, how to reduce the cost and the failure rate of hardware and improve the robustness while meeting the oil temperature estimation of water cooling and oil cooling electric drive is a technical problem to be solved in the field. Disclosure of Invention In view of the above, this summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The application aims to provide an oil temperature estimation method, device, system and medium for an electric drive system, which can reduce cost and hardware failure rate and improve robustness while meeting the oil temperature estimation of water cooling and oil cooling electric drive. In order to achieve the above purpose, the application has the following technical scheme: in a first aspect, an embodiment of the present application provides a method for estimating an oil temperature of an electric drive system, including: Acquiring the oil temperature at the last moment of a vehicle electric drive system; according to the first preset dimensionless coefficient, the current moment motor torque and the current moment motor rotating speed, calculating to obtain the first heating value of the reduction gearbox at the current moment and the second heating value of the motor; according to a second preset dimensionless coefficient, the motor rotating speed at the current moment, the oil temperature at the last moment