Thermal management control method for power system of electric vehicle

Abstract

The invention relates to the technical field of electric vehicle thermal management, in particular to an electric vehicle power system thermal management control method, which is provided with a motor, a motor controller, a high-voltage distributor DCDC, a high-voltage OBC, a water pump and a VCU, and is characterized in that the VCU controls the water pump to operate; the high-voltage distributor DCDC, the high-voltage OBC, the motor and the motor controller upload own temperature values to the VCU, the water pump and the cooling fan for PWM (Pulse Width Modulation) wave form control, and the specific running speed is sequentially adjusted, so that the problems that the cost is high because a thermal management system is configured at the present stage, and the temperature is too high if the thermal management system is not configured are solved; and the power of the whole vehicle is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management of electric vehicles, and in particular to a thermal management control method for a power system of an electric vehicle. Background Art

[0002] The power system of electric vehicles mainly includes motors, motor controllers, and high-voltage distributors. Due to its own particularity, the battery system usually has its own cooling and heating circuit.

[0003] The electric drive system is afraid of heat but not cold. When the temperature is too high, the power of the whole vehicle will drop. In severe cases, it will cause demagnetization of the electric drive system and permanent failure. Currently, many electric vehicles on the market are equipped with heat pump systems, but due to the high cost, they are not very popular, especially commercial trucks, which are rarely equipped. The thermal management system mainly controls the water pump and cooling fan in the cooling circuit. The quality of control will affect the overheating of the vehicle components, the reduction of the vehicle power, the dynamic performance, the NVH of the vehicle, the energy consumption of the vehicle, etc. Summary of the invention

[0004] The present invention provides a thermal management control method for an electric vehicle power system, which not only ensures that components will not have over-temperature failures, but also reduces the energy consumption of the entire vehicle and improves the NVH performance of the entire vehicle, thereby ensuring the driving comfort of the driver. It solves the problem that the cost of configuring a thermal management system at this stage is relatively high, and if the thermal management system is not configured, the temperature is too high, which will cause a power reduction to the entire vehicle.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a thermal management control method for an electric vehicle power system, which is provided with a motor, a motor controller, a high-voltage distributor DCDC, a high-voltage OBC, a water pump and a VCU, wherein the VCU controls the operation of the water pump, and the high-voltage distributor DCDC, the high-voltage OBC, the motor and the motor controller upload their own temperature values ​​to the VCU, and the water pump and the cooling fan can be controlled in the form of PWM waves to adjust the operating speed in turn, specifically, comprising the following steps: Step S1, the VCU constantly detects the motor temperature, the motor controller temperature, the high-voltage distributor DCDC temperature and the high-voltage OBC temperature; Step S2, multiple MAPs are set in the VCU. The MAP is a three-dimensional table based on vehicle speed, component temperature value, and ambient temperature. The output is the PWM control duty cycle of the water pump and the fan. The larger the duty cycle, the faster the required speed of the water pump and the fan, and the more the vehicle needs to dissipate heat quickly. The calibration idea is: when the vehicle speed is higher, the calibrated duty cycle value is smaller, making full use of the characteristics of high vehicle speed and air convection for rapid heat exchange of the high-voltage components of the vehicle. When the ambient temperature is lower, the calibrated water pump and fan duty cycle values ​​are smaller, making full use of the characteristics of low ambient temperature, air convection, large temperature difference of high-voltage components of the vehicle, and more heat exchange; when the component temperature value is higher, the calibrated duty cycle value is larger, and the formula used is Q = h*A*(tw-t∞)=q*A, where q is the heat exchanged between the solid surface per unit area and the fluid per unit time, called heat flux density, with the unit of W / m^2; tw and t∞ are the temperatures of the solid surface and the fluid, respectively, with the unit of K, and Q is the heat dissipation. The duty cycle is output through Map to control the speed of the water pump and cooling fan.

[0006] It is further specified that when the VCU detects that the driver suddenly opens the throttle too wide or the torque of the vehicle's electric drive system is greater than a certain value and lasts for more than a calibrated time of 4 seconds, the VCU must revise the duty cycle demand values ​​of the water pump and fan after the above-mentioned Map.

[0007] It is further specified that when the driver turns the key to turn off the vehicle, the VCU detects the temperature of the motor, the motor controller, the high-voltage distributor DCDC, and the high-voltage OBC. When the temperature of any component is greater than a certain value, it will intelligently delay the low-voltage power supply, control the fan and water pump to continue running, and lower the temperature of the components as soon as possible; this operating condition is called Afterrun.

[0008] It is further defined that during the Afterrun working condition, in order to take into account the NVH performance of the entire vehicle, the fan speed is calibrated to a smaller value. During the Afterrun working condition, the maximum delay time is the calibrated value of 60 seconds. Within the 60-second delay, if the motor temperature, motor controller temperature, DCDC temperature, and OBC temperature are all detected to be lower than the calibrated value, the vehicle VCU will control the power to be cut off immediately without forcing a delay of 60 seconds, thereby saving energy and taking into account NVH performance.

[0009] It is further defined that fast charging and slow charging functions are provided; both the fast charging charging seat and the slow charging charging seat are equipped with temperature sensors, the slow charging seat temperature is T1 and T2, and the fast charging seat temperature is T3 and T4. The slow charging seat temperature T1 and T2 are sent to the VCU by the high-voltage OBC, and the fast charging seat temperature T3 and T4 are sent to the VCU by the battery manager BMS. The VCU detects the above four temperature values ​​in real time and uses them to determine the ambient temperature. The VCU is equipped with a clock chip and can perform real-time timing.

[0010] Further defined, the specific steps are as follows: Step S4, judging whether the charging time of the fast charging seat and the slow charging seat is greater than the calibration value of 30 minutes from the last charging time, if so, the ambient temperature at this time = (T1+T2+T3+T4) / 4, after more than 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature, if not, the following steps are judged; Further defined, step S5, judging whether the charging time of the fast charging seat is greater than the calibrated value of 30 minutes, and the charging time of the slow charging seat is less than 30 minutes, if so, the ambient temperature at this time = (T3+T4) / 2, if it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature, if it is less than 30 minutes, it is considered that the charging seat is not consistent with the ambient temperature, if otherwise, the judgment of the following steps is performed; Step S6, determine whether the charging time of the slow charging seat is greater than the calibrated value of 30 minutes, and the charging time of the fast charging seat is less than 30 minutes. If so, the ambient temperature at this time = (T1+T4) / 2. If it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature; if it is less than 30 minutes, it is considered that the charging seat is not consistent with the ambient temperature.

[0011] The beneficial effects of adopting the above technical solution are: Taking full advantage of the special properties of electric vehicles and intelligently estimating the ambient temperature around the vehicle, the control method uses the two key factors of vehicle speed and ambient temperature to control the speed of the water pump and fan. This can minimize the demand for water pump and fan speed, save electricity, and improve the NVH performance of the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the overall logic control schematic diagram of the present invention; Figure 2 This is a logical diagram of the VCU detecting fast charging and slow charging in the present invention. DETAILED DESCRIPTION

[0013] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0014] The present invention is a thermal management control method for an electric vehicle power system. In addition to ensuring that components do not have over-temperature failures, it also reduces the energy consumption of the entire vehicle and improves the NVH performance of the entire vehicle, ensuring the driving comfort of the driver. It solves the problem that the cost of configuring a thermal management system at this stage is high, and if the thermal management system is not configured, the temperature is too high, which will cause a power drop to the entire vehicle.

[0015] Specifically, Figure 1 and Figure 2 As shown, a thermal management control method for an electric vehicle power system is provided with a motor, a motor controller, a high-voltage distributor DCDC, a high-voltage OBC, a water pump and a VCU. The VCU controls the operation of the water pump. The high-voltage distributor DCDC, the high-voltage OBC, the motor and the motor controller upload their own temperature values ​​to the VCU. The water pump and the cooling fan can be controlled in the form of PWM waves to adjust the speed of operation in turn. Specifically, the method includes the following steps: Step S1, VCU constantly detects the motor temperature, motor controller temperature, high-voltage distributor DCDC temperature and high-voltage OBC temperature; Step S2, multiple MAPs are set in the VCU. The MAP is a three-dimensional table based on vehicle speed, component temperature value, and ambient temperature. The output is the PWM control duty cycle of the water pump and fan. The larger the duty cycle, the faster the required speed of the water pump and fan, and the more the vehicle needs to dissipate heat quickly. The calibration idea is: when the vehicle speed is higher, the calibrated duty cycle value is smaller, making full use of the characteristics of high vehicle speed and air convection for rapid heat exchange of high-voltage components of the vehicle. When the ambient temperature is lower, the calibrated water pump and fan duty cycle values ​​are smaller, making full use of the characteristics of low ambient temperature, air convection, large temperature difference of high-voltage components of the vehicle, and more heat exchange; when the component temperature value is higher, the calibrated duty cycle value is larger, and the formula used is Q = h*A*(tw-t∞)=q*A, where q is the heat exchanged between the solid surface per unit area and the fluid per unit time, called heat flux density, with the unit of W / m^2; tw and t∞ are the temperatures of the solid surface and the fluid, respectively, with the unit of K, and Q is the heat dissipation. The duty cycle is output through Map to control the speed of the water pump and cooling fan. When the VCU detects that the driver suddenly opens the throttle or the torque of the vehicle's electric drive system is greater than a certain value and continues for more than the calibrated time of 4 seconds, the VCU will revise the duty cycle demand value of the water pump and fan after the above Map. When the driver turns the key to turn off the vehicle, the vehicle controller VCU detects the motor temperature, motor controller temperature, and high voltage When the temperature of the distributor DCDC or the high-voltage OBC is higher than a certain value, the low-voltage power will be intelligently delayed to control the fan and water pump to continue running, so as to reduce the temperature of the components as soon as possible. This working condition is called Afterrun. In the Afterrun working condition, in order to take into account the NVH performance of the whole vehicle, the fan speed is calibrated to a smaller value. In the Afterrun working condition, the maximum delay time is the calibrated value of 60 seconds. Within the delay of 60 seconds, if the motor temperature, motor controller temperature, DCDC temperature, and OBC temperature are all detected to be lower than the calibrated value, the vehicle VCU will control the power to be turned off immediately without forcibly delaying to 60 seconds, saving energy and taking into account NVH performance.

[0016] Due to the particularity of electric vehicles, electric vehicles generally have the functions of fast charging and slow charging. There are two fast charging seats and two slow charging seats. Both the fast charging seat and the slow charging seat are equipped with temperature sensors. The slow charging seat temperature is T1 and T2, and the fast charging seat temperature is T3 and T4. The high-voltage OBC sends the slow charging seat temperature T1 and T2 to the VCU, and the battery manager BMS sends the fast charging seat temperature T3 and T4 to the VCU. The VCU detects the above four temperature values ​​in real time and uses them to determine the ambient temperature. The VCU has a clock chip that can perform real-time timing. The specific steps are as follows: Step S4, judging whether the charging time of the fast charging seat and the slow charging seat is greater than the calibration value of 30 minutes from the last charging time. If so, the ambient temperature at this time = (T1+T2+T3+T4) / 4. After more than 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature. If not, the following steps are performed; Step S5, judging whether the charging time of the fast charging seat is greater than the calibrated value of 30 minutes, and the charging time of the slow charging seat is less than 30 minutes. If so, the ambient temperature at this time = (T3+T4) / 2. If it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature. If it is less than 30 minutes, it is considered that the temperature of the charging seat is not consistent with the ambient temperature. Otherwise, the judgment of the following steps is performed; Step S6, determine whether the charging time of the slow charging seat is greater than the calibrated value of 30 minutes, and the charging time of the fast charging seat is less than 30 minutes. If so, the ambient temperature at this time = (T1+T2) / 2. If it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature; if it is less than 30 minutes, it is considered that the temperature of the charging seat is not consistent with the ambient temperature.

[0017] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above-mentioned concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A thermal management control method for an electric vehicle power system, comprising a motor, a motor controller, a high-voltage distributor DCDC, a high-voltage OBC, a water pump and a VCU, characterized in that: The VCU controls the operation of the water pump, and the high-voltage distributor DCDC, high-voltage OBC, motor and motor controller upload their own temperature values ​​to the VCU. The water pump and cooling fan can be controlled in the form of PWM waves to adjust the specific speed of operation in turn, including the following steps: Step S1, the VCU constantly detects the motor temperature, the motor controller temperature, the high-voltage distributor DCDC temperature and the high-voltage OBC temperature; Step S2, multiple MAPs are set in the VCU. The MAP is a three-dimensional table based on vehicle speed, component temperature value, and ambient temperature. The output is the PWM control duty cycle of the water pump and the fan. The larger the duty cycle, the faster the required speed of the water pump and the fan, and the more the vehicle needs to dissipate heat quickly. The calibration idea is: when the vehicle speed is higher, the calibrated duty cycle value is smaller, making full use of the characteristics of high vehicle speed and air convection for rapid heat exchange of the high-voltage components of the vehicle. When the ambient temperature is lower, the calibrated water pump and fan duty cycle values ​​are smaller, making full use of the characteristics of low ambient temperature, air convection, large temperature difference of high-voltage components of the vehicle, and more heat exchange; when the component temperature value is higher, the calibrated duty cycle value is larger, and the formula used is Q = h*A*(tw-t∞)=q*A, where q is the heat exchanged between the solid surface per unit area and the fluid per unit time, called heat flux density, with the unit of W / m^2; tw and t∞ are the temperatures of the solid surface and the fluid, respectively, with the unit of K, and Q is the heat dissipation. The duty cycle is output through Map to control the speed of the water pump and cooling fan.

2. The electric vehicle power system thermal management control method according to claim 1, characterized in that: When the VCU detects that the driver suddenly opens the throttle too wide or the torque of the vehicle's electric drive system is greater than a certain value and lasts for more than a calibrated time of 4 seconds, the VCU will revise the duty cycle demand values ​​of the water pump and fan after the above-mentioned Map.

3. The electric vehicle power system thermal management control method according to claim 1, characterized in that: When the driver turns the key to turn off the vehicle, the vehicle controller VCU detects the temperature of the motor, motor controller, high-voltage distributor DCDC, and high-voltage OBC. When the temperature of any component is greater than a certain value, it will intelligently delay the low-voltage power supply, control the fan and water pump to continue running, and reduce the temperature of the components as soon as possible. This operating condition is called Afterrun.

4. The electric vehicle power system thermal management control method according to claim 3, characterized in that: During the Afterrun condition, in order to take into account the NVH performance of the entire vehicle, the fan speed is calibrated to a smaller value. During the Afterrun condition, the maximum delay time is the calibrated value of 60 seconds. Within the 60-second delay, if the motor temperature, motor controller temperature, DCDC temperature, and OBC temperature are all detected to be lower than the calibrated value, the vehicle VCU will control the power to be turned off immediately without forcing a delay of 60 seconds, thus saving energy and taking into account NVH performance.

5. The electric vehicle power system thermal management control method according to claim 1, characterized in that: It is equipped with fast charging and slow charging functions; both the fast charging charging station and the slow charging charging station are equipped with temperature sensors. The temperature of the slow charging station is T1 and T2, and the temperature of the fast charging station is T3 and T4. The high-voltage OBC sends the slow charging station temperature T1 and T2 to the VCU, and the battery manager BMS sends the fast charging station temperature T3 and T4 to the VCU. The VCU detects the above four temperature values ​​in real time and uses them to determine the ambient temperature. The VCU is equipped with a clock chip and can perform real-time timing.

6. The electric vehicle power system thermal management control method according to claim 5, characterized in that: The specific steps are as follows: Step S4, judging whether the charging time of the fast charging seat and the slow charging seat is greater than the calibration value of 30 minutes from the last charging time. If so, the ambient temperature at this time = (T1+T2+T3+T4) / 4. After more than 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature. If not, the following steps are performed; Step S5, judging whether the charging time of the fast charging seat is greater than the calibrated value of 30 minutes, and the charging time of the slow charging seat is less than 30 minutes. If so, the ambient temperature at this time = (T3+T4) / 2. If it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature. If it is less than 30 minutes, it is considered that the charging seat is not consistent with the ambient temperature. Otherwise, the judgment of the following steps is performed; Step S6, determine whether the charging time of the slow charging seat is greater than the calibrated value of 30 minutes, and the charging time of the fast charging seat is less than 30 minutes. If so, the ambient temperature at this time = (T1+T4) / 2. If it exceeds 30 minutes, it is considered that the temperature of the charging seat is consistent with or balanced with the ambient temperature; if it is less than 30 minutes, it is considered that the charging seat is not consistent with the ambient temperature.

Images