A safe electronic water pump control method

Abstract

The present application relates to the field of new energy vehicle thermal management, and particularly relates to a safe electronic water pump control method. In the present application, the control method starts the electronic water pump from a high duty cycle and gradually reduces the duty cycle after determining that the electric drive system has a cooling demand, thereby effectively avoiding dry running and other faults that are prone to occur when the electronic water pump starts from a low to a high duty cycle. Compared with the prior art, the control method in the present embodiment adopts a strategy of gradually reducing the duty cycle after starting from a high duty cycle, which does not cause overshoot and is relatively simple and stable in control adjustment. In addition, the cooling demand is determined again each time the duty cycle is reduced, and if the cooling demand is reduced, the duty cycle is immediately reduced, so that the cooling demand can be met while effectively saving energy consumption and reducing noise impact.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy vehicle thermal management, in particular to a safe electronic water pump control method. BACKGROUND

[0002] At present, new energy vehicles are mainly electric vehicles and hybrid vehicles, which all have electric drive systems. The electric drive system needs to be cooled according to the temperature of the system or the temperature of related parts when working. The electronic water pump is the power source for controlling the entire water circuit.

[0003] There are two main control methods for the existing electronic water pump of the electric drive circuit. One is to divide the temperature into different levels according to the temperature of the motor, motor controller, OBC, DCDC, and cooling liquid, and to use different electronic water pump duty cycles according to different temperature levels. The duty cycle is low when the temperature is low, and the duty cycle is high when the temperature is high. The second is to use PI control of the electronic water pump duty cycle according to the above temperature. The disadvantages of these two control methods are as follows: 1. The response speed is slow according to the temperature level division, and it is most likely to cause the IGBT temperature to be too high during instantaneous high power, resulting in vehicle power limitation. The electronic water pump is difficult to start at low duty cycle, causing dry running or locked rotor failure. 2. PI control requires too many temperature parameters to control, and each controlled part is sensitive to temperature. It is not easy to implement and is prone to overshoot or slow response. The control software implementation cost is high, and the calibration is difficult. 3. During driving, especially at high speed, sudden failure may cause power to drop, speed to be limited, and serious traffic accidents. SUMMARY

[0004] The present application provides a safe electronic water pump control method, which can solve some or some defects in the prior art.

[0005] According to the safe electronic water pump control method of the present application, the following steps are included:

[0006] Step S1, divide the cooling demand of the electric drive system into cooling levels n to 1 according to the required cooling capacity from high to low, a total of n levels; and divide the duty cycle of the electronic water pump into duty cycles 1 to n according to the high to low from high to low, a total of n levels.

[0007] Step S2, determine whether the electric drive system has cooling demand, if there is demand, control the electronic water pump to work according to the duty cycle 1;

[0008] Step S3, determine whether the current cooling demand meets the cooling level n, if it meets, continue to work according to the duty cycle 1; if it does not meet, work according to the duty cycle 2;

[0009] Step S4, judging whether the current cooling demand meets the cooling level n-1, if yes, returning to step S3, if not, working according to duty ratio 3;

[0010] Step S5, judging whether the current cooling demand meets the cooling level n-2, if yes, returning to step S4, if not, working according to duty ratio 4;

[0011] Step S6 to Sn are similar to the above.

[0012] Step Sn, judging whether the current cooling demand meets the cooling level 3, if yes, returning to step Sn-1, if not, working according to duty ratio n-1.

[0013] Step Sn+1, judging whether the current cooling demand meets the cooling level 2, if yes, returning to step Sn, if not, working according to duty ratio n.

[0014] Step Sn+2, judging whether the current cooling demand meets the cooling level 1, if yes, returning to step Sn+1, if not, continuing to work according to duty ratio n and stopping working after ts.

[0015] Specifically, after judging that the electric drive system has a cooling demand, the electronic water pump is started from a high duty ratio and gradually reduced, so that dry running and other faults that are prone to occur when the electronic water pump is started from a low to a high duty ratio can be effectively avoided.

[0016] The PI control adjustment in the prior art needs too many parameters to control the temperature, and it is not easy to implement because the sensitivity of each controlled part to the temperature is different, and it is prone to overshoot or slow response, and the control software implementation cost is high and difficult to calibrate.

[0017] Compared with the prior art, the control method in the application gradually reduces the duty ratio from a high starting strategy, which does not cause overshoot and is relatively simple and stable in control adjustment.

[0018] In addition, the cooling demand is judged again each time the duty ratio is reduced, and if the cooling demand is reduced, the duty ratio is immediately reduced, so that the cooling demand can be met while effectively saving energy consumption and reducing noise.

[0019] As a preferred embodiment, the cooling demand of the electric drive system is divided based on the water temperature and the temperature of the related parts.

[0020] Specifically, the cooling demand in the application is obtained by comprehensively weighing the water temperature and the temperature of the related parts, so as to provide a basis for the division of the cooling level.

[0021] Preferably, the high-low of the duty cycle in step S1 is positively correlated with the high-low of the rotating speed; the specific duty cycle is calibrated according to the current cooling level.

[0022] Specifically, the specific duty cycle in the application is positively correlated with the actual rotating speed, so that the duty cycle can be adjusted by directly adjusting the rotating speed. The user can also calibrate the duty cycle level in the actual process by adjusting the rotating speed according to different vehicles and different driving conditions.

[0023] Preferably, step S2 determines whether the electric drive system has a cooling demand according to the actual values of the water temperature and the temperature of the related components.

[0024] Preferably, in steps S3 to Sn+2, before reducing the electronic water pump duty cycle each time, it is necessary to determine whether the accelerator pedal opening is greater than a and the accelerator opening increase rate is greater than b. If so, the control needs to be restarted from the duty cycle 1.

[0025] Specifically, in the control method of the application, the accelerator pedal opening and the accelerator opening increase rate are determined each time the electronic water pump duty cycle is reduced; the accelerator pedal opening and the opening increase rate are detected in real time, and once a or b is reached, the electronic water pump restarts from the highest rotating speed, i.e. the duty cycle 1. The purpose of this determination is that a large accelerator opening or an instantaneous increase in the accelerator opening will cause the IGBT (Insulated Gate Bipolar Transistor) temperature of the motor controller to increase rapidly, and simply relying on the cooling level to control the duty cycle cannot meet the rapid temperature increase.

[0026] Therefore, the application can provide sufficient cooling in time to avoid a rapid temperature rise when the accelerator opening becomes large through this step, and further, the maximum cooling through the highest rotating speed, i.e. the duty cycle 1, can effectively avoid the situation that the vehicle power is limited due to the over-temperature of the IGBT (Insulated Gate Bipolar Transistor).

[0027] Preferably, a and b are calibrated according to different vehicle models.

[0028] The application has the following technical effects due to the above technical solutions:

[0029] 1. The electronic water pump starts from a high duty cycle and gradually reduces, avoiding the dry running and other faults that easily occur when the electronic water pump starts from a low duty cycle.

[0030] 2. The duty cycle is gradually reduced after starting according to the cooling level, effectively saving energy and reducing noise.

[0031] 3. The electronic water pump duty cycle is related to the accelerator pedal opening and the change rate, preventing the instantaneous temperature of the electric drive system from being too high to cause power limitation and ensuring driving safety. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a safe electronic water pump control method of embodiment 1, wherein n is preferably 5, a flowchart of the specific embodiment. DETAILED DESCRIPTION

[0033] The application will be further described in detail below in conjunction with the drawings and embodiments.

[0034] Embodiment 1

[0035] In conjunction with Figure 1 , the embodiment provides a safe electronic water pump control method, which comprises the following steps: step S1, the cooling demand of the electric drive system is divided into n levels from cooling level n to cooling level 1 according to the required cooling capacity from high to low, a total of n levels; the duty cycle of the electronic water pump is divided into duty cycle 1 to duty cycle n according to high to low, a total of n levels.

[0036] Step S2, judge whether the electric drive system has cooling demand, if there is demand, control the electronic water pump to work according to the duty cycle 1;

[0037] Step S3, judge whether the current cooling demand meets the cooling level n, if yes, continue to work according to the duty cycle 1; if not, work according to the duty cycle 2;

[0038] Step S4, judge whether the current cooling demand meets the cooling level n-1, if yes, return to step S3, if not, work according to the duty cycle 3;

[0039] Step S5, judge whether the current cooling demand meets the cooling level n-2, if yes, return to step S4, if not, work according to the duty cycle 4;

[0040] Step S6 to Sn in this way;

[0041] Step Sn, judge whether the current cooling demand meets the cooling level 3, if yes, return to step Sn-1, if not, work according to the duty cycle n-1;

[0042] Step Sn+1, judge whether the current cooling demand meets the cooling level 2, if yes, return to step Sn, if not, work according to the duty cycle n;

[0043] Step Sn+2, judge whether the current cooling demand meets the cooling level 1, if yes, return to step Sn+1, if not, continue to work according to the duty cycle n for ts and then stop working.

[0044] Specifically, in the control method in this embodiment, after it is judged that the electric drive system has cooling demand, the electronic water pump is started from high duty ratio and gradually reduced; thus, dry running and other faults that are prone to occur when the electronic water pump is started from low to high duty ratio can be effectively avoided.

[0045] The PI control adjustment in the prior art needs too many parameters for controlling temperature, and it is not easy to implement because the controlled parts are different in temperature sensitivity, and it is prone to overshoot or slow response, and the control software implementation cost is high and difficult to calibrate.

[0046] Compared with the prior art, the control method in this embodiment adopts the strategy of gradually reducing the duty ratio from high starting, and does not have overshoot phenomenon and is relatively simple and stable in control adjustment.

[0047] In addition, at each time of reducing the duty ratio, the cooling demand is judged again, and if the cooling demand is reduced, the duty ratio is immediately reduced, so that the cooling demand can be met while effectively saving energy consumption and reducing noise impact.

[0048] In this embodiment, the cooling demand of the electric drive system in step S1 is divided based on the water temperature and the temperature of the related parts.

[0049] Specifically, the cooling demand in this embodiment is obtained by comprehensively weighing the water temperature and the temperature of the related parts, so as to provide a basis for the division of the cooling level.

[0050] In this embodiment, the high and low of the duty ratio in step S1 is positively correlated with the high and low of the speed; the size of the specific duty ratio is calibrated according to the current cooling level.

[0051] Specifically, in this embodiment, the specific duty ratio is positively correlated with the actual speed, so that the duty ratio can be adjusted by directly adjusting the speed. The duty ratio level in the actual process can also be calibrated by adjusting the speed for different vehicles and different driving conditions.

[0052] In this embodiment, step S2 judges whether the electric drive system has cooling demand according to the actual values of the water temperature and the temperature of the related parts.

[0053] In this embodiment, in steps S3 to Sn+2, before reducing the duty ratio of the electronic water pump each time, it is needed to judge whether the accelerator pedal opening is greater than a and whether the accelerator opening increasing rate is greater than b, and if so, the control needs to be restarted from the duty ratio 1.

[0054] Specifically, in the control method of the embodiment, each time the duty cycle of the electronic water pump is reduced, the accelerator pedal opening and the accelerator opening increase rate are judged; the accelerator pedal opening and the opening increase rate are detected in real time, and once a or β is reached, the electronic water pump works from the highest speed, i.e. the duty cycle 1. The purpose of the judgment is that a large accelerator opening or an instantaneous increase in the accelerator opening will cause the temperature of the IGBT (Insulated Gate Bipolar Transistor) of the motor controller to rapidly increase, and the duty cycle control relying on the cooling level alone cannot meet the influence of the rapid temperature increase.

[0055] Therefore, through the step, the embodiment can provide sufficient cooling in time to avoid the rapid temperature rise when the accelerator opening is large, and further, the maximum cooling through the highest speed, i.e. the duty cycle 1, can effectively avoid the situation that the power of the whole vehicle is limited due to the over-temperature of the IGBT (Insulated Gate Bipolar Transistor).

[0056] In the embodiment, a and β are calibrated according to different vehicle models.

[0057] It is easy to understand that those skilled in the art can obtain other embodiments by combining, splitting, recombining, etc. the embodiments of the present application on the basis of one or several embodiments provided in the present application, and these embodiments do not exceed the protection scope of the present application.

[0058] In summary, the above only describes the preferred embodiments of the present application, and any changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the patent of the present application.

Claims

1. A safe electronic water pump control method, characterized by, It comprises the following steps: Step S1, the cooling demand of the electric drive system is divided into n levels from cooling level n to cooling level 1 according to the required cooling capacity from high to low; the duty cycle of the electronic water pump is divided into n levels from duty cycle 1 to duty cycle n according to the high to low; Step S2, determine whether the electric drive system has cooling demand, if there is demand, control the electronic water pump to work according to the duty cycle 1; Step S3, determine whether the current cooling demand meets the cooling level n, if yes, continue to work according to the duty cycle 1; if not, work according to the duty cycle 2; Step S4, determine whether the current cooling demand meets the cooling level n-1, if yes, return to step S3, if not, work according to the duty cycle 3; Step S5, determine whether the current cooling demand meets the cooling level n-2, if yes, return to step S4, if not, work according to the duty cycle 4; Step S6 to Sn in this way; Step Sn, determine whether the current cooling demand meets the cooling level 3, if yes, return to step Sn-1, if not, work according to the duty cycle n-1; Step Sn+1, determine whether the current cooling demand meets the cooling level 2, if yes, return to step Sn, if not, work according to the duty cycle n; Step Sn+2, determine whether the current cooling demand meets the cooling level 1, if yes, return to step Sn+1, if not, continue to work according to the duty cycle n for ts and then stop working; In steps S3 to Sn+2, before reducing the duty cycle of the electronic water pump, it is necessary to determine whether the accelerator pedal opening is greater than a and the accelerator opening increasing rate is greater than β, if the accelerator pedal opening is greater than a or the accelerator opening increasing rate is greater than β, it is necessary to start control from the duty cycle 1 again.

2. A safe electronic water pump control method according to claim 1, characterized in that: In step S1, the cooling demand of the electric drive system is divided according to the water temperature and the temperature of related components.

3. A safe electronic water pump control method according to claim 1, characterized in that: In step S1, the high and low of the duty cycle is positively related to the high and low of the speed; the specific size of the duty cycle is obtained according to the current cooling level.

4. The method of claim 2, wherein: In step S2, the actual value of the water temperature and the temperature of related components is used to determine whether the electric drive system has cooling demand.

5. The safe electronic water pump control method according to claim 1, characterized in that: α and β will be calibrated according to different vehicle models.

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