CN107499176B

CN107499176B - Method and device for cooling an electric drive system of a vehicle

Info

Publication number: CN107499176B
Application number: CN201710313485.3A
Authority: CN
Inventors: 高宝泉
Original assignee: Borgward Automotive China Co Ltd
Current assignee: Borgward Automotive China Co Ltd
Priority date: 2017-05-05
Filing date: 2017-05-05
Publication date: 2020-09-18
Anticipated expiration: 2037-05-05
Also published as: CN107499176A

Abstract

The present disclosure relates to a method and apparatus for cooling an electric drive system of a vehicle, the method comprising: acquiring a predicted cooling demand of the cooling system according to the heating power of the electric drive system; acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system; a control parameter of the cooling system is determined based on the predicted cooling demand and the real-time cooling demand. The control strategy of the cooling system is determined by combining the predicted cooling demand and the real-time cooling demand, so that the corresponding cooling capacity can be timely distributed according to the actual cooling demand, the energy consumption of the system is reduced, and the problem of regulation hysteresis is avoided.

Description

Method and device for cooling an electric drive system of a vehicle

Technical Field

The present disclosure relates to the field of vehicle technologies, and in particular, to a cooling method and apparatus for a vehicle electric drive system.

Background

The cooling performance of the driving motor, which is a main source of traction power of a pure electric vehicle, has a great influence on the dynamic performance, the economical efficiency and the drivability of the whole vehicle. There are two main methods in the prior art for cooling an electric drive system of a pure electric vehicle: full-time maximum capacity cooling methods and real-time cooling methods that dynamically adjust cooling capacity based on monitoring drive motor temperature and calculating motor power. The mode of the former is simple and easy to implement, a full-time maximum capacity cooling method is generally adopted in a commercial pure electric vehicle, although the method has certain advantages in the aspects of complexity of a whole vehicle control strategy and manufacturing cost, the energy is greatly wasted, and the method is not suitable when the energy conservation and emission reduction are increasingly promoted. In the latter mode, the temperature change of the electric drive system has hysteresis compared with that of a heat source (heating power of the electric drive system), namely, the heat accumulated by the electric drive system does not disappear immediately after the drive current is reduced or becomes zero, and the heat dissipation needs a certain time, so that the temperature change is collected in real time by a sensor and then is dynamically adjusted, and the hysteresis of the adjustment is obvious.

Disclosure of Invention

The invention aims to provide a cooling method and a cooling device of a vehicle electric driving system, which are used for solving the problems of energy waste and hysteresis of the existing cooling method.

According to a first aspect of an embodiment of the present disclosure, there is provided a method of cooling an electric drive system of a vehicle, the method comprising:

acquiring a predicted cooling demand of a cooling system according to the heating power of the electric drive system;

acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system;

determining a control parameter for the cooling system based on the predicted cooling demand and the real-time cooling demand.

Optionally, before the obtaining the predicted cooling demand of the cooling system according to the heat generation power of the electric drive system, the method further includes:

acquiring heating power of the electric drive system, system temperature of the electric drive system and cooling liquid temperature of the cooling system;

wherein the heating power of the electric drive system comprises a driving motor heating power of the electric drive system; the system temperature of the electric drive system comprises a current ambient temperature of the electric drive system, a drive motor body temperature of the electric drive system, and a drive motor controller temperature; and the cooling liquid temperature of the cooling system comprises the inlet temperature of a cooling loop of the front driving motor and the inlet temperature of a cooling loop of the rear driving motor.

Optionally, the obtaining the predicted cooling demand of the cooling system according to the heating power of the electric drive system includes:

determining the cooling demand percentage of the cooling liquid according to the inlet temperature of the front driving motor cooling loop and the inlet temperature of the rear driving motor cooling loop;

determining a cooling demand percentage of a driving motor according to the heating power of the driving motor, the body temperature of the driving motor and the controller temperature of the driving motor, wherein the heating power of the driving motor comprises the heating power of a front driving motor and the heating power of a rear driving motor, the body temperature of the driving motor comprises the body temperature of the front driving motor and the body temperature of the rear driving motor, the controller temperature of the driving motor comprises the controller temperature of the front driving motor and the controller temperature of the rear driving motor, and the cooling demand percentage of the driving motor comprises the cooling demand percentage of the front driving motor and the cooling demand percentage of the rear driving motor;

determining the coolant cooling demand percentage and the drive motor cooling demand percentage as the predicted cooling demand.

Optionally, determining the percentage of cooling demand of the cooling liquid according to the inlet temperature of the front driving motor cooling loop and the inlet temperature of the rear driving motor cooling loop comprises:

acquiring the optimal temperature of the cooling liquid to be kept at the current ambient temperature by utilizing the corresponding relation between the preset ambient temperature and the cooling liquid temperature;

selecting a maximum of the front drive motor cooling circuit inlet temperature and the rear drive motor cooling circuit inlet temperature;

acquiring a difference value between the optimal temperature and the maximum value as a control target increment value of cooling liquid cooling requirements;

and carrying out normalization processing according to the control target increment value and a preset weighing value of the cooling tolerance of the driving system to obtain the cooling demand percentage of the cooling liquid.

Optionally, determining the percentage of cooling demand of the driving motor according to the heating power of the driving motor, the body temperature of the driving motor and the controller temperature of the driving motor includes:

filtering the heating power of the driving motor, wherein the filtering comprises first-order filtering and gradient filtering;

performing integral processing within a preset time period on the heating power of the drive motor after filtering processing to obtain a heat loss evaluation accumulated value of the drive motor within the preset time period;

converting the driving motor heat loss evaluation accumulated value into a driving motor heat loss value in the preset time period by using a preset algorithm;

determining the percentage of cooling demand of the driving motor according to the heat loss value of the driving motor, the temperature of the driving motor body and the temperature of the controller of the electric driving motor;

when the temperature of the drive motor controller is the temperature of the front drive motor controller, the cooling demand percentage of the drive motor is the cooling demand percentage of the front drive motor; the driving motor current is the heating power of the rear driving motor, the body temperature of the driving motor is the body temperature of the rear driving motor, and when the temperature of the driving motor controller is the temperature of the rear driving motor controller, the cooling demand percentage of the driving motor is the cooling demand percentage of the rear driving motor.

Optionally, the obtaining a real-time cooling demand of the cooling system according to the system temperature of the electric drive system includes:

filtering the front drive motor body temperature, the rear drive motor body temperature, the front drive motor controller temperature and the rear drive motor controller temperature to obtain a current temperature;

determining a temperature interval in which the current temperature is located, wherein the temperature interval comprises a basic control area, a proportional control area or a limit control area, the temperature range of the proportional control area is higher than that of the basic control area, and the temperature range of the limit control area is higher than that of the proportional control area;

acquiring a corresponding cooling system control strategy according to the temperature interval, wherein the cooling system control strategy comprises the following steps: setting parameters of the rotating speed of a fan, the rotating speed of a water pump and the opening degree of three open valves of the cooling circuit;

determining a real-time cooling demand of the cooling system according to the cooling system control strategy.

Optionally, the determining a control parameter of the cooling system according to the predicted cooling demand and the real-time cooling demand includes:

obtaining a control parameter for the cooling system by coupling the predicted cooling demand and the real-time cooling demand;

wherein, the coupling mode includes: selecting a maximum value, a weighted average or a combination of the selected maximum value and the weighted average.

According to a second aspect of an embodiment of the present disclosure, there is provided a cooling apparatus of a vehicle electric drive system, the apparatus including:

the predicted cooling demand obtaining module is used for obtaining the predicted cooling demand of the cooling system according to the heating power of the electric drive system;

the real-time cooling demand acquisition module is used for acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system;

and the control parameter determining module is used for determining the control parameters of the cooling system according to the predicted cooling demand and the real-time cooling demand.

Optionally, the apparatus further comprises:

a parameter obtaining module, configured to obtain a heating power of the electric drive system, a system temperature of the electric drive system, and a coolant temperature of the cooling system before obtaining a predicted cooling demand of the cooling system according to the heating power of the electric drive system;

Optionally, the predicted cooling demand obtaining module includes:

the cooling liquid requirement determining submodule is used for determining the percentage of cooling liquid requirement according to the inlet temperature of the front driving motor cooling loop and the inlet temperature of the rear driving motor cooling loop;

a driving motor cooling demand determination submodule for determining a driving motor cooling demand percentage according to the driving motor heating power, the driving motor body temperature and the driving motor controller temperature, wherein the driving motor heating power includes a front driving motor heating power and a rear driving motor heating power, the driving motor body temperature includes a front driving motor body temperature and a rear driving motor body temperature, the driving motor controller temperature includes a front driving motor controller temperature and a rear driving motor controller temperature, and the driving motor cooling demand percentage includes a front driving motor cooling demand percentage and a rear driving motor cooling demand percentage;

a pre-cooling demand determination submodule for determining the percentage of cooling demand of the cooling liquid and the percentage of cooling demand of the drive motor as the predicted cooling demand.

Optionally, the cooling liquid demand determination submodule includes:

the optimal temperature acquisition submodule is used for acquiring the optimal temperature of the cooling liquid to be kept at the current ambient temperature by utilizing the corresponding relation between the preset ambient temperature and the temperature of the cooling liquid;

a temperature maximum selection submodule for selecting a maximum of the front drive motor cooling circuit inlet temperature and the rear drive motor cooling circuit inlet temperature;

a difference value obtaining submodule, configured to obtain a difference value between the optimal temperature and the maximum value, where the difference value is used as a control target incremental value of cooling demand of the cooling liquid;

and the normalization processing submodule is used for performing normalization processing according to the control target increment value and a preset weighing value of the cooling tolerance of the electric drive system to obtain the cooling demand percentage of the cooling liquid.

Optionally, the drive motor cooling demand determination submodule includes:

the heating power calculation and filtering processing submodule is used for carrying out filtering processing on the heating power of the driving motor, and the filtering processing comprises first-order filtering and gradient filtering;

the integral processing submodule is used for carrying out integral processing within a preset time period on the heating power of the drive motor after filtering processing, and obtaining a heat loss evaluation accumulated value of the drive motor within the preset time period;

the heat loss value calculation operator module is used for converting the heat loss evaluation accumulated value of the driving motor into a heat loss value of the driving motor in the preset time period by using a preset algorithm;

the cooling demand determining submodule is used for determining the percentage of the cooling demand of the driving motor according to the heat loss value of the driving motor, the temperature of the driving motor body and the temperature of the driving motor controller;

Optionally, the real-time cooling demand obtaining module includes:

the current temperature acquisition submodule is used for carrying out filtering processing on the temperature of the front drive motor body, the temperature of the rear drive motor body, the temperature of the front drive motor controller and the temperature of the rear drive motor controller to obtain the current temperature;

the temperature interval determining submodule is used for determining a temperature interval in which the current temperature is positioned, and the temperature interval comprises a basic control area, a proportional control area or a limit control area, wherein the temperature range of the proportional control area is higher than that of the basic control area, and the temperature range of the limit control area is higher than that of the proportional control area;

a control strategy obtaining sub-module, configured to obtain a corresponding cooling system control strategy according to the temperature interval, where the cooling system control strategy includes: setting parameters of the rotating speed of a fan, the rotating speed of a water pump and the opening degree of three open valves of the cooling circuit;

and the real-time cooling demand determining submodule is used for determining the real-time cooling demand of the cooling system according to the cooling system control strategy.

Optionally, the control parameter determining module is configured to:

The present disclosure provides a cooling method and apparatus for a vehicle electric drive system by obtaining a predicted cooling demand of a cooling system based on a heating power of the electric drive system; acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system; determining a control parameter for the cooling system based on the predicted cooling demand and the real-time cooling demand. The cooling demand of the cooling system is predicted through the heating power of the electric drive system, the real-time cooling demand of the cooling system is obtained by monitoring the system temperature of the electric drive system in real time, the control strategy of the cooling system is determined through combination of the heating power and the system temperature, the corresponding cooling capacity can be distributed according to the actual cooling demand, the energy consumption of the system is reduced, and the problem of adjustment hysteresis is avoided.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a flow chart illustrating a method of cooling an electric drive system of a vehicle in accordance with an exemplary embodiment;

FIG. 2 is a flow chart illustrating another method of cooling an electric drive system of a vehicle in accordance with an exemplary embodiment;

FIG. 3 is a schematic configuration diagram of a cooling system of an electric vehicle;

FIG. 4 is a flow chart illustrating a method of cooling an electric drive system of a vehicle in accordance with an exemplary embodiment;

FIG. 5 is a flow chart illustrating a method of cooling an electric drive system of a vehicle in accordance with an exemplary embodiment;

FIG. 6 is a flow chart illustrating a method of cooling an electric drive system of a vehicle in accordance with an exemplary embodiment;

FIG. 7 is a block diagram illustrating a cooling arrangement of a vehicle electric drive system in accordance with an exemplary embodiment;

FIG. 8 is a block diagram illustrating a cooling arrangement of another vehicle electric drive system in accordance with an exemplary embodiment;

FIG. 9 is a block diagram illustrating a predicted cooling demand acquisition module in accordance with an exemplary embodiment;

FIG. 10 is a block diagram illustrating a coolant demand determination submodule, according to an exemplary embodiment;

FIG. 11 is a block diagram illustrating a drive motor cooling demand determination submodule in accordance with an exemplary embodiment;

FIG. 12 is a block diagram illustrating a real-time cooling demand acquisition module in accordance with an exemplary embodiment.

Description of the reference numerals

301: three-way valve

302: front drive motor system

3021: front driving motor

3022: front drive motor controller

303: rear drive motor system

3031: rear drive motor

3032: rear drive motor controller

304: water pump

305: cooling liquid radiator

306: fan with cooling device

307: cooling loop expansion pot

3081: ambient temperature sensor

3082: inlet temperature sensor of cooling loop of front driving motor

3083: inlet temperature sensor of cooling loop of rear driving motor

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

Before the present disclosure is introduced to provide a cooling method and device for a vehicle electric drive system, an application scenario related to the present disclosure is first introduced, where the vehicle electric drive system generally includes a drive motor and a cooling system, the drive motor includes a drive motor body and a controller thereof, and the cooling system generally includes a cooling circuit containing a coolant, a radiator, a water pump, a fan, and the like. The temperature change of the driving motor and the cooling liquid can not be caused immediately by the change of the heating power of the driving motor, for example, when the whole vehicle stops running at a high speed or is switched to run at a low speed, the heat accumulated by the electric driving system can not disappear immediately when the power of the driving motor becomes zero or less, the heat is dissipated or the heat of the system reaches balance again for a certain time, the time required by the balance depends on the control of the cooling capacity of the current system, and the excessive control can effectively reduce the cooling or balancing time but can cause energy waste; conversely, too little control can significantly increase system cooling time. This is because the root cause of the temperature variation of the electric drive system (including the drive motor, the drive motor controller, and the coolant thereof) is the result of the accumulation of heat of the respective components and the accumulation of the dissipation speed over time, and therefore the temperature variation of the electric drive system has hysteresis in comparison with the heat source itself (the heating power of the electric drive system). If the control start threshold of the cooling system is set to be high, a transient temperature overshoot phenomenon exists, the hysteresis effect cannot be obviously improved if closed-loop control is adopted, and meanwhile, the oscillation time of the closed-loop control also increases the complexity of a control algorithm.

In addition, the evaluation of the cooling capacity at this time cannot depend on the heating power calculated by the phase current of the motor for prediction, so that the real-time cooling control method based on temperature acquisition needs to be combined to make up for the shortage of predicted cooling.

In addition, what is referred to is that there are some cooling methods of complex control that predict the driving condition of the whole vehicle by combining map data, driving road conditions and the whole vehicle condition, which mainly aims at the traditional vehicle driven by the internal combustion engine, and presume the road condition according to the terrain data and then pre-control the cooling system of the whole vehicle, but the method has certain limitation: the same road can have different requirements on the cooling system due to the driving habits of different drivers, and the same cooling control can influence the good performance of the power performance of the whole vehicle to a certain extent.

Based on the consideration, the invention provides a prediction and real-time combined cooling control method for motor cooling control of a pure electric vehicle, which can solve the problems of energy waste and hysteresis of the existing cooling method.

FIG. 1 is a flow chart illustrating a method of cooling an electric drive system of a vehicle, as shown in FIG. 1, according to an exemplary embodiment, which may include the steps of:

and step 110, acquiring a predicted cooling demand of the cooling system according to the heating power of the electric drive system.

The heating power of the electric drive system comprises the heating power of a drive motor of the electric drive system, the working current, the voltage, the rotating speed and the torque of the drive motor are mainly used as calculation basis, the heating power is used for predicting the temperature rise condition of the drive system of the drive motor in a certain period in the future, the control requirement of the cooling liquid temperature of the cooling system is calculated according to the temperature rise condition, and finally the control requirement of the cooling liquid temperature, namely the predicted cooling demand can be output in a percentage mode. In addition, because the heat dissipation performance of the driving motor has a larger relationship with the ambient temperature and the temperature of the cooling liquid, the current ambient temperature of the electric drive system and the temperature of the cooling liquid of the cooling system can be combined when the predicted cooling demand of the cooling system is obtained according to the heating power of the electric drive system, wherein the cooling liquid is in the cooling loop of the cooling system.

And step 120, acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system.

The system temperature of the electric drive system comprises the current ambient temperature of the electric drive system, the body temperature of a drive motor of the electric drive system and the controller temperature of the drive motor, and in general, the drive motor may comprise a front drive motor and a rear drive motor, so that the heating power of the drive motor comprises the heating power of the front drive motor and the heating power of the rear drive motor, the body temperature of the drive motor comprises the body temperature of the front drive motor and the body temperature of the rear drive motor, the controller temperature of the drive motor comprises the controller temperature of the front drive motor and the controller temperature of the rear drive motor, and the coolant temperature of the cooling system comprises the inlet temperature of a cooling loop of the front drive motor and the inlet temperature of a cooling loop of the rear drive motor.

Additionally, acquiring the real-time cooling demand is complementary to the predicted cooling demand, particularly in the following two situations: the first situation is a start phase when the current ambient temperature is high; the second case is a low speed stage or an idling stage after a long-time high-speed travel. In the above two cases, although the driving heating power of the driving motor is not large, a continuous high heat dissipation or cooling requirement is still required, and at this time, the heat dissipation capability of the cooling circuit of the whole driving motor system can be adjusted in real time according to the temperature of the cooling liquid and the temperature of the driving motor body.

It should be noted that the

above steps

110 and 120 can be performed synchronously, that is, the analysis of the predicted cooling demand and the real-time cooling demand can be performed on the cooling system at the same time, so that the cooling demand obtained in the two steps can be combined in the following step 130.

In step 130, control parameters of the cooling system are determined based on the predicted cooling demand and the real-time cooling demand.

Illustratively, this step is obtaining a control parameter for the cooling system by coupling the predicted cooling demand and the real-time cooling demand.

Wherein, the coupling mode includes: the maximum value, the weighted average or a combination of the maximum value and the weighted average is selected.

After the predicted cooling demand and the real-time cooling demand are respectively determined in the

steps

110 and 120, the predicted cooling demand and the real-time cooling demand are coupled to determine a control parameter of the cooling system, and it can be seen that the control parameter is determined based on the combination of the pre-cooling capacity and the actual cooling demand, and is obtained by combining with the monitoring of the real-time cooling demand of the electric drive system, so that the driving capability of the drive motor can be effectively ensured, the power reduction phenomenon of the drive motor due to overheating can be avoided all the time, the cooling capacity matched with the cooling demand of the electric drive system can be timely provided for the electric drive system in the cooling process, the energy waste caused by excessive output of the cooling capacity can be avoided, and the influence of insufficient output of the cooling capacity on the electric drive system can be avoided.

Illustratively, when the coupling of step 130 is performed, a gradient constraint of the control parameter may be further added, which is mainly used for controlling the unsmooth execution of the cooling device, and the gradient constraint can be used as the control parameter to achieve adjustability of the control fineness on the one hand; on the other hand, the control requirements of the cooling device can be adapted. For example, some cooling water pumps 204 require a minimum change step size of the control amount of 5%.

In summary, the present disclosure provides a cooling method for a vehicle electric drive system, which obtains a predicted cooling demand of the cooling system according to a heating power of the electric drive system; acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system; a control parameter of the cooling system is determined based on the predicted cooling demand and the real-time cooling demand. Because the heat dissipation performance of the driving motor has a large relation with the ambient temperature and the temperature of the cooling liquid, and the heat productivity of the driving motor is generally related to the heat dissipation power consumption of the driving motor, the heat dissipation requirement of the whole cooling loop is predicted by combining the quantity of the driving motor, the ambient temperature and the temperature of the cooling liquid, meanwhile, the temperature of the driving motor and the temperature of the controller of the driving motor are monitored in real time to obtain the real-time cooling requirement quantity, the control strategy of the cooling system is determined by combining the quantity of the driving motor, the ambient temperature and the temperature of the cooling liquid, the corresponding cooling capacity can be distributed according to the actual cooling requirement, the energy consumption of the system is reduced, and.

FIG. 2 is a flow chart illustrating another method of cooling an electric drive system of a vehicle, according to an exemplary embodiment, as shown in FIG. 2, prior to the steps of the embodiment of FIG. 1, further comprising the steps of:

in step 140, the heating power of the electric drive system, the system temperature of the electric drive system, and the cooling liquid temperature of the cooling system are obtained.

The heating power of the electric drive system comprises the heating power of a drive motor of the electric drive system; the system temperature of the electric drive system comprises the current environment temperature of the electric drive system, the body temperature of a drive motor of the electric drive system and the temperature of a drive motor controller; the cooling system has a cooling fluid temperature that includes a front drive motor cooling circuit inlet temperature and a rear drive motor cooling circuit inlet temperature.

Illustratively, a pick-up system of an electric drive system of a typical electric vehicle includes a cooling circuit as shown in fig. 3, in which a three-open valve 301 is used to adjust a flow rate ratio of a cooling liquid in the cooling system, and a cooling apparatus includes: the water pump 304, the fan 306, and the cooling circuit expansion pot 307 are directly controlled by a VCU (Vehicle Control Unit, chinese) through a LIN (Local Interconnect Network, chinese) communication bus, so as to cool the electric drive system. The opening degree of the three-open valve 301, the rotating speed of the water pump 304 and the rotating speed of the fan 306 are parameters to be controlled by the cooling system, and the overall cooling capacity of the electric drive system is adjusted through reasonable adjustment of the opening degree of the three-open valve 301, the rotating speed of the water pump 304 and the rotating speed of the fan 306, so that the aim of timely and effectively cooling the electric drive system is fulfilled.

The current ambient temperature of the electric drive system of the vehicle is acquired by an ambient temperature sensor 3081, and the acquired temperature data is transmitted to the VCU through a CAN (Controller Area Network, chinese) bus. The coolant temperature includes a front drive motor cooling loop inlet temperature and a rear drive motor cooling loop inlet temperature, and a front drive motor cooling loop inlet temperature sensor 3082 and a rear drive motor cooling loop inlet temperature sensor 3083 may be used to collect the coolant temperature and transmit it to the VCU using the LIN bus. The heating power calculation data (current, voltage, rotating speed and torque) of the driving motor of the electric driving system, the body temperature of the driving motor and the controller temperature of the driving motor CAN be acquired by the front driving motor system 302 and the rear driving motor system 303, and the acquired data are transmitted to the VCU through the CAN bus. The front drive motor system 302 includes a front drive motor 3021 and a front drive motor controller 3022, and correspondingly, the rear drive motor system 303 includes a front drive motor 3031 and a rear drive motor controller 3032. In some cooling systems, the coolant temperatures sensed by the front and rear drive motor cooling circuit inlet temperature sensors 3082 and 3083 may be sensed by the front and rear

drive motor systems

302 and 303, respectively, while in some cooling systems they may be sensed directly by the VCU.

Based on the cooling circuit shown in fig. 3, the step of obtaining the predicted cooling demand of the cooling system according to the heating power of the electric drive system in step 110 may include: and acquiring the predicted cooling demand of the cooling system according to the current environment temperature, the cooling liquid temperature, the heating power of the driving motor, the temperature of the driving motor body and the temperature of the driving motor controller.

Specifically, the predicted cooling demand is composed of the cooling liquid temperature acquired by the front drive motor cooling circuit inlet temperature sensor 3082 and the rear drive motor cooling circuit inlet temperature sensor 3083, the current ambient temperature acquired by the ambient temperature sensor 3081, the cooling liquid cooling demand percentage obtained by looking up a table and calculating, and the drive motor cooling demand percentage obtained by evaluating and calculating the cooling demand percentages of the front drive motor system 302 and the rear drive motor system 303. The flow of calculation of the predicted cooling demand may be as shown in fig. 4 and 5.

The step 120 of obtaining the real-time cooling demand of the cooling system according to the system temperature of the electric drive system is to obtain the real-time cooling demand of the cooling system according to the body temperature of the driving motor and the controller temperature of the driving motor, and the calculation flow of the real-time cooling demand may be as shown in fig. 6.

Illustratively, fig. 4 is a flowchart illustrating a method of cooling an electric drive system of a vehicle, according to an exemplary embodiment, as shown in fig. 4, the step 110 of obtaining a predicted cooling demand of the cooling system based on a heating power of the electric drive system in fig. 1 comprises the steps of:

and step 111, determining the cooling demand percentage of the cooling liquid according to the inlet temperature of the front driving motor cooling loop and the inlet temperature of the rear driving motor cooling loop.

By way of example, this step may include: firstly, acquiring the optimal temperature of the cooling liquid to be kept at the current ambient temperature by utilizing the corresponding relation between the preset ambient temperature and the cooling liquid temperature; secondly, selecting the maximum value of the inlet temperature of the front driving motor cooling loop and the inlet temperature of the rear driving motor cooling loop; thirdly, acquiring a difference value between the optimal temperature and the maximum value as a control target incremental value of cooling liquid cooling requirements; and finally, carrying out normalization processing according to the control target increment value and a preset weighing value of the cooling tolerance of the electric drive system to obtain the cooling demand percentage of the cooling liquid. The measurement value of the cooling tolerance of the electric drive system is obtained by calculation of empirical data and experimental data, and needs to consider the corresponding time of the cooling action of the electric drive system, the cooling performance of a cooling circuit and the energy consumption index of the electric drive system, and the system with the smaller tolerance value has more sensitive response, which also means that the system has more frequent action and more energy consumption.

And 112, determining the cooling demand percentage of the driving motor according to the heating power of the driving motor, the body temperature of the driving motor and the controller temperature of the driving motor. The driving motor heating power comprises front driving motor heating power and rear driving motor heating power, the driving motor body temperature comprises front driving motor body temperature and rear driving motor body temperature, the driving motor controller temperature comprises front driving motor controller temperature and rear driving motor controller temperature, and the driving motor cooling demand percentage comprises front driving motor cooling demand percentage and rear driving motor cooling demand percentage.

The drive motor heating power calculation data (current, voltage, speed and torque), drive motor body temperature and drive motor controller temperature as described in step 140 are calculations of how the front drive motor cooling demand percentage and the rear drive motor cooling demand percentage are determined from the drive motor heating power, the drive motor body temperature and the drive motor controller temperature, as transmitted to the VCU by the front drive motor system 302 and the rear drive motor system 303 over the CAN bus, see the embodiment of fig. 5 below.

It should be noted that step 111 and step 112 may be performed synchronously, that is, the percentage of cooling liquid required and the percentage of cooling required for the driving motor at the same time may be obtained, and then step 113 may be performed in combination to determine the predicted cooling required amount.

And step 113, determining the cooling demand percentage of the cooling liquid and the cooling demand percentage of the driving motor as the predicted cooling demand.

Illustratively, fig. 5 is a flowchart illustrating a method of cooling a vehicle electric drive system according to an exemplary embodiment, wherein determining a drive motor cooling demand percentage as a function of drive motor heating power, drive motor body temperature, and drive motor controller temperature as set forth in step 112 of fig. 4, as shown in fig. 5, comprises the steps of:

step 1121, performing filtering processing on the heating power of the driving motor, wherein the filtering processing includes first-order filtering and gradient filtering.

And step 1122, performing integration processing on the filtered heating power of the driving motor within a preset time period to obtain an estimated accumulated value of heat loss of the driving motor within the preset time period.

Step 1123, converting the driving motor heat loss estimation accumulated value into a driving motor heat loss value within a preset time period by using a preset algorithm.

Step 1124, determining a percentage of cooling demand for the drive motor based on the heat loss value of the drive motor, the body temperature of the drive motor, and the controller temperature of the drive motor.

The heating power of the driving motor is the heating power of the front driving motor, the body temperature of the driving motor is the body temperature of the front driving motor, and when the temperature of the driving motor controller is the temperature of the front driving motor controller, the cooling demand percentage of the driving motor is the cooling demand percentage of the front driving motor. The heating power of the driving motor is the heating power of the rear driving motor, the temperature of the driving motor body is the temperature of the rear driving motor body, and when the temperature of the driving motor controller is the temperature of the rear driving motor controller, the cooling demand percentage of the driving motor is the cooling demand percentage of the rear driving motor.

Illustratively, after the input voltage, the input current, the output rotation speed and the output torque of the front drive motor system are obtained, and the equivalent heating power of the front drive motor system is calculated, the heating power is firstly subjected to non-negativity processing, and is processed by adopting first-order filtering and gradient filtering described in step 1121. Step 1122 is then performed to integrate the power generated by the front drive motor in order to obtain an estimated cumulative value of heat loss for the front drive motor over a certain period of time. The accumulated value is converted to obtain an estimated heat loss value of the front driving motor in a specific time period, in step 1123, wherein the conversion coefficient from the accumulated heat loss value of the front driving motor to the heat loss conversion is determined by an experimentally calibrated method. Finally, in step 1124, the heat loss value of the driving motor obtained in step 1123 is used as an input together with the body temperature of the front driving motor, and the cooling demand percentage of the front driving motor is finally obtained through table lookup and calculation (the table data can be obtained through calibration of a calibration experiment). Similarly, when the heating power and the body temperature of the rear drive motor calculated by using the input voltage, the input current, the output rotating speed and the output torque of the rear drive motor system are used, the percentage of the cooling requirement of the rear drive motor can be obtained through the processes.

Illustratively, fig. 6 is a flowchart illustrating a method of cooling an electric drive system of a vehicle according to an exemplary embodiment, and as shown in fig. 6, the step 120 of fig. 1 of obtaining a real-time cooling demand of the cooling system according to a system temperature of the electric drive system includes the steps of:

and step 121, filtering the front drive motor body temperature, the rear drive motor body temperature, the front drive motor controller temperature and the rear drive motor controller temperature to obtain the current temperature.

And step 122, determining a temperature interval in which the current temperature is positioned, wherein the temperature interval comprises a basic control area, a proportional control area or a limit control area, the temperature range of the proportional control area is higher than that of the basic control area, and the temperature range of the limit control area is higher than that of the proportional control area.

Step 123, obtaining a corresponding cooling system control strategy according to the temperature interval, where the cooling system control strategy includes: the fan 306 speed, the water pump 304 speed and the opening of the three-way valve 301 of the cooling circuit.

For example, in the basic control region, the basic control amounts of the water pump 304 and the fan 306 in the cooling system may be set to 15% and 40% of the rated control amount; in the limit control area, the maximum control amount of the water pump 304 and the fan 306 in the cooling system can be set to be 85% and 95% of the rated control amount; the values of the basic control quantity and the maximum control quantity of the cooling equipment are obtained through calibration experiments and performance parameters of parts. In the proportional control region, the cooling demand of the drive motor is between the basic control amount and the maximum control amount of the cooling device, and in the proportional control region, the output control amounts of the water pump 304 and the fan 306 depend on the current drive motor controller temperature and the temperature of the drive motor body, and the temperatures are basically in piecewise linear relation with the output control amount of the cooling device in the cooling system, generally speaking, the higher the temperature value is, the larger the cooling demand value is.

In the basic control region and the limit control region, the ratio of the opening degrees of the three-way valve 301 may be maintained at 0.5: 0.5. the proportional control range of the opening degree of the three-way valve 301 is 0.3: 0.7 to 0.7: and 0.3, the range is obtained by measuring the flow rate of the cooling liquid in the pipeline and the comprehensive evaluation of the heat dissipation capacity of the pipeline.

In a typical electrically driven vehicle, the front drive motor system 302 and the rear drive motor system 303, during the above calculation, calculate their respective real-time cooling demands, and the difference between the two cooling demands is realized by adjusting the opening of the three-way valve 301 for proportional distribution of the flow rates of the front and rear drive coolants.

Fig. 7 is a block diagram illustrating a cooling arrangement for a vehicle electric drive system, according to an exemplary embodiment, and as shown in fig. 7, the arrangement 700 includes:

the predicted cooling demand obtaining module 710 is configured to obtain a predicted cooling demand of the cooling system according to the current environment temperature, the coolant temperature, the heating power of the driving motor, the body temperature of the driving motor, and the controller temperature of the driving motor.

And a real-time cooling demand obtaining module 720, configured to obtain a real-time cooling demand of the cooling system according to the temperature of the driving motor body and the temperature of the driving motor controller.

A control parameter determination module 730 for determining a control parameter of the cooling system based on the predicted cooling demand and the real-time cooling demand.

Further, fig. 8 is a block diagram illustrating another cooling apparatus for a vehicle electric drive system according to an exemplary embodiment, and as shown in fig. 8, the apparatus 700 further includes:

and the parameter acquisition module 740 is used for acquiring the heating power of the electric drive system, the system temperature of the electric drive system and the cooling liquid temperature of the cooling system.

Optionally, fig. 9 is a block diagram illustrating a predicted cooling demand obtaining module according to an exemplary embodiment, and as shown in fig. 9, the predicted cooling demand obtaining module 710 includes:

the cooling liquid requirement determining submodule 711 is configured to determine a cooling liquid requirement percentage according to the front drive motor cooling circuit inlet temperature and the rear drive motor cooling circuit inlet temperature.

The driving motor cooling demand determining submodule 712 is configured to determine a driving motor cooling demand percentage according to the driving motor heating power, the driving motor body temperature and the driving motor controller temperature, where the driving motor heating power includes the front driving motor heating power and the rear driving motor heating power, the driving motor body temperature includes the front driving motor body temperature and the rear driving motor body temperature, the driving motor controller temperature includes the front driving motor controller temperature and the rear driving motor controller temperature, and the driving motor cooling demand percentage includes the front driving motor cooling demand percentage and the rear driving motor cooling demand percentage.

A pre-cooling demand determination sub-module 713 for determining the percentage of cooling demand of the cooling liquid and the percentage of cooling demand of the driving motor as the predicted cooling demand.

Alternatively, fig. 10 is a block diagram of a coolant demand determination submodule, shown in fig. 10, of the coolant demand determination submodule, including:

and the optimal temperature obtaining sub-module 7111 is configured to obtain an optimal temperature that the cooling liquid needs to maintain at the current ambient temperature by using a preset corresponding relationship between the ambient temperature and the temperature of the cooling liquid.

A temperature maximum selection sub-module 7112 for selecting a maximum of the front drive motor cooling circuit inlet temperature and the rear drive motor cooling circuit inlet temperature.

And a difference value obtaining sub-module 7113, configured to obtain a difference value between the optimal temperature and the maximum value as a control target incremental value of the cooling liquid cooling demand.

And the normalization processing submodule 7114 is used for performing normalization processing according to the control target increment value and a preset weighing value of the cooling tolerance of the driving system to acquire the cooling demand percentage of the cooling liquid.

Alternatively, FIG. 11 is a block diagram illustrating a drive motor cooling demand determination sub-module, according to an exemplary embodiment, and as shown in FIG. 9, a drive motor cooling demand determination sub-module 712, including:

and the filtering processing submodule 7121 is used for carrying out filtering processing on the heating power of the driving motor, and the filtering processing comprises first-order filtering and gradient filtering.

And the integration processing submodule 7122 is used for performing integration processing on the filtered heating power of the driving motor within a preset time period to obtain an evaluation accumulated value of heat loss of the driving motor within the preset time period.

And the heat loss value operator module 7123 is used for converting the heat loss evaluation accumulated value of the driving motor into a heat loss value of the driving motor within a preset time period by using a preset algorithm.

And the cooling demand determination submodule 7124 is used for determining the percentage of cooling demand of the driving motor according to the heat loss value of the driving motor, the body temperature of the driving motor and the controller temperature of the driving motor.

When the temperature of the drive motor controller is the temperature of the front drive motor controller, the cooling demand percentage of the drive motor is the cooling demand percentage of the front drive motor; the heating power of the driving motor is the heating power of the rear driving motor, the temperature of the driving motor body is the temperature of the rear driving motor body, and when the temperature of the driving motor controller is the temperature of the rear driving motor controller, the cooling demand percentage of the driving motor is the cooling demand percentage of the rear driving motor.

Optionally, fig. 12 is a block diagram illustrating a real-time cooling demand obtaining module according to an exemplary embodiment, and as shown in fig. 12, the real-time cooling demand obtaining module 720 includes:

the current temperature obtaining sub-module 721 is configured to perform filtering processing on the front drive motor body temperature, the rear drive motor body temperature, the front drive motor controller temperature, and the rear drive motor controller temperature, so as to obtain a current temperature.

And the temperature interval determination submodule 722 is used for determining a temperature interval in which the current temperature is positioned, wherein the temperature interval comprises a basic control area, a proportional control area or a limit control area, the temperature range of the proportional control area is higher than that of the basic control area, and the temperature range of the limit control area is higher than that of the proportional control area.

A control strategy obtaining sub-module 723, configured to obtain a corresponding cooling system control strategy according to the temperature interval, where the cooling system control strategy includes: and setting parameters of the rotating speed of the fan, the rotating speed of the water pump and the opening degree of the three-way valve of the cooling circuit.

A real-time cooling demand determination submodule 724 is configured to determine a real-time cooling demand of the cooling system based on the cooling system control strategy.

Optionally, the control parameter determining module 730 is configured to:

the control parameters of the cooling system are derived by coupling the predicted cooling demand and the real-time cooling demand.

In summary, the present disclosure provides a cooling apparatus for a vehicle electric drive system, which obtains a predicted cooling demand of the cooling system according to a heating power of the electric drive system; acquiring the real-time cooling demand of the cooling system according to the system temperature of the electric drive system; a control parameter of the cooling system is determined based on the predicted cooling demand and the real-time cooling demand. Because the heat dissipation performance of the driving motor has a large relation with the ambient temperature and the temperature of the cooling liquid, and the heat productivity of the driving motor is generally related to the heat dissipation power consumption of the driving motor, the heat dissipation requirement of the whole cooling loop is predicted by combining the quantity of the driving motor, the ambient temperature and the temperature of the cooling liquid, meanwhile, the temperature of the driving motor and the temperature of the controller of the driving motor are monitored in real time to obtain the real-time cooling requirement quantity, the control strategy of the cooling system is determined by combining the quantity of the driving motor, the ambient temperature and the temperature of the cooling liquid, the corresponding cooling capacity can be distributed according to the actual cooling requirement, the energy consumption of the system is reduced, and.

Preferred embodiments of the present disclosure are described in detail above with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details in the above embodiments, and a number of simple modifications of the technical method of the present disclosure may be made within the scope of the technical idea of the present disclosure, and these simple modifications all fall within the protective scope of the present disclosure.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A method of cooling an electric drive system of a vehicle, the method comprising:

determining a control parameter for the cooling system based on the predicted cooling demand and the real-time cooling demand;

before the deriving a predicted cooling demand for a cooling system from a heating power of the electric drive system, the method further comprises:

wherein the heating power of the electric drive system comprises a driving motor heating power of the electric drive system; the system temperature of the electric drive system comprises a current ambient temperature of the electric drive system, a drive motor body temperature of the electric drive system, and a drive motor controller temperature; the cooling liquid temperature of the cooling system comprises the inlet temperature of a cooling loop of the front driving motor and the inlet temperature of a cooling loop of the rear driving motor;

the obtaining of the predicted cooling demand of the cooling system based on the heating power of the electric drive system includes:

determining a cooling liquid cooling demand percentage according to the front drive motor cooling loop inlet temperature and the rear drive motor cooling loop inlet temperature, wherein the cooling liquid cooling demand percentage is the cooling demand of the cooling liquid expressed in percentage form;

determining a driving motor cooling demand percentage according to the driving motor heating power, the driving motor body temperature and the driving motor controller temperature, wherein the driving motor cooling demand percentage is the driving motor cooling demand expressed in percentage form, the driving motor heating power comprises a front driving motor heating power and a rear driving motor heating power, the driving motor body temperature comprises a front driving motor body temperature and a rear driving motor body temperature, the driving motor controller temperature comprises a front driving motor controller temperature and a rear driving motor controller temperature, and the driving motor cooling demand percentage comprises a front driving motor cooling demand percentage and a rear driving motor cooling demand percentage;

2. The method of claim 1, wherein determining a percentage cooling demand of the cooling liquid based on the front drive motor cooling circuit inlet temperature and the rear drive motor cooling circuit inlet temperature comprises:

and carrying out normalization processing according to the control target increment value and a preset weighing value of the cooling tolerance of the electric drive system to obtain the cooling demand percentage of the cooling liquid.

3. The method of claim 1, wherein determining a drive motor cooling demand percentage based on the drive motor heating power, the drive motor body temperature, and the drive motor controller temperature comprises:

determining the cooling demand percentage of the driving motor according to the heat loss value of the driving motor, the temperature of the driving motor body and the temperature of the driving motor controller;

when the heating power of the driving motor is the heating power of the front driving motor, the body temperature of the driving motor is the body temperature of the front driving motor, and the controller temperature of the driving motor is the controller temperature of the front driving motor, the cooling demand percentage of the driving motor is the cooling demand percentage of the front driving motor; when the heating power of the driving motor is the heating power of the rear driving motor, the body temperature of the driving motor is the body temperature of the rear driving motor, and the temperature of the driving motor controller is the controller temperature of the rear driving motor, the cooling demand percentage of the driving motor is the cooling demand percentage of the rear driving motor.

4. The method of claim 1, wherein said deriving a real-time cooling demand of the cooling system from a system temperature of the electric drive system comprises:

5. The method of claim 1, wherein determining the control parameter for the cooling system based on the predicted cooling demand and the real-time cooling demand comprises:

6. A cooling apparatus of a vehicle electric drive system, characterized in that the apparatus comprises:

a control parameter determination module for determining a control parameter of the cooling system based on the predicted cooling demand and the real-time cooling demand;

the predicted cooling demand obtaining module includes:

a cooling liquid demand percentage determination submodule for determining a cooling liquid demand percentage, which is the cooling demand of the cooling liquid expressed in percentage, according to the front drive motor cooling loop inlet temperature and the rear drive motor cooling loop inlet temperature;

a driving motor cooling demand percentage determination submodule for determining a driving motor cooling demand percentage according to the driving motor heating power, the driving motor body temperature and the driving motor controller temperature, wherein the driving motor cooling demand percentage is the driving motor cooling demand expressed in percentage form, the driving motor heating power includes a front driving motor heating power and a rear driving motor heating power, the driving motor body temperature includes a front driving motor body temperature and a rear driving motor body temperature, the driving motor controller temperature includes a front driving motor controller temperature and a rear driving motor controller temperature, and the driving motor cooling demand percentage includes a front driving motor cooling demand percentage and a rear driving motor cooling demand percentage;

a predicted cooling demand determination submodule configured to determine the percentage of cooling demand of the cooling liquid and the percentage of cooling demand of the drive motor as the predicted cooling demand.

7. The apparatus of claim 6, wherein the coolant demand percentage determination submodule comprises:

8. The apparatus of claim 6, wherein the drive motor cooling demand percentage determination submodule comprises:

the filtering processing submodule is used for carrying out filtering processing on the heating power of the driving motor, and the filtering processing comprises first-order filtering and gradient filtering;

9. The apparatus of claim 6, wherein the real-time cooling demand acquisition module comprises:

10. The apparatus of claim 6, wherein the control parameter determination module is configured to: