A pure electric logistics vehicle cooling fan control method

Abstract

The application discloses a control method of a pure electric logistics vehicle radiating fan, which comprises the following steps: determining the working state of the radiating fan according to current vehicle state data; calculating the control parameter of the radiating fan according to the temperature data of the component to be radiated; and controlling the radiating fan according to the working state and the control parameter of the radiating fan. The application has the advantages that the radiating risk of the logistics vehicle is effectively controlled, the NVH in the control process is reduced, and the user experience is improved.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation control, and in particular to a method for controlling the cooling fan of a pure electric logistics vehicle. Background Technology

[0002] With the development of commercial logistics vehicles, pure electric commercial logistics vehicles are increasingly favored by short-haul freight drivers due to their excellent economy, power, and stability. In the overall vehicle thermal management design, the cooling fan is an indispensable component. How to design a stable, reliable, and cost-effective control scheme with the same hardware is an ongoing research topic.

[0003] In automotive thermal management design, the cooling fan is the main component for heat exchange between the engine compartment and the outside air. Its function is to blow hot air from the engine compartment to the outside, continuously cooling the engine compartment. Different speeds remove different amounts of heat per unit time.

[0004] In the field of commercial logistics vehicles, cooling fans are generally divided into two categories: relay-controlled high and low speed fans and brushless fans. Their hardware principles are different, and their control strategies are also different.

[0005] In the commercial logistics vehicle sector, due to stringent cost control requirements, a dedicated controller is generally not provided; instead, it is integrated into components such as a TMS (Traffic Management System). If the overall vehicle cost is too high to accommodate a TMS controller, then fan control becomes problematic.

[0006] In current mainstream control logic, different software strategies must be switched for each different fan, resulting in low efficiency and a high error rate. Furthermore, the brushless fan generates significant whistling noise due to resonance during shutdown, which is detrimental to the overall NVH (noise, vibration, and harshness) of the vehicle. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a cooling fan control method for pure electric logistics vehicles, so as to effectively control the heat dissipation risk of logistics vehicles, reduce NVH during the control process, and improve user experience.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a control method for a cooling fan of a pure electric logistics vehicle, comprising determining the working state of the cooling fan based on the current vehicle status data; and calculating the control parameters of the current cooling fan based on the collected temperature data of the components to be cooled.

[0009] Control the cooling fan according to its operating status and control parameters.

[0010] The control strategy for the cooling fan is integrated into the vehicle controller in software form; the vehicle controller executes the corresponding cooling fan control strategy according to the type of cooling fan to control the operation of the cooling fan.

[0011] The cooling fan control strategy is integrated into the vehicle controller (VCU). The cooling fan control strategy includes a first control strategy and a second control strategy, which correspond to the control of the brushless cooling fan and the high-speed and low-speed cooling fan, respectively.

[0012] The system collects the status of the power battery in real time to determine whether it is under high voltage. When it is under high voltage, it collects the temperature of the components to be cooled and the request information from the air conditioner to determine the corresponding working status of the cooling fan. The working status of the cooling fan includes two states: on and off.

[0013] When the cooling fan is determined to be in the on state, the temperature data of each component to be cooled is collected in real time, and the duty cycle of the brushless cooling fan or the high and low speed parameters of the high and low speed fans are controlled based on the temperature data.

[0014] When the cooling fan is on, the temperature data of each component to be cooled is acquired, and the corresponding fan control duty cycle is obtained based on the temperature of each component. The maximum value of all fan control duty cycles is taken as the control duty cycle to drive and control the brushless cooling fan.

[0015] Current control parameters for cooling fans include the control duty cycle of brushless cooling fans or the high and low speed settings of high and low speed cooling fans.

[0016] After the cooling fan is turned on, the temperature data is monitored in real time. When the temperature rises and causes a change in the control duty cycle calculated by the temperature, the current control duty cycle is immediately adjusted to the changed control duty cycle. When the temperature drops and causes a change in the control duty cycle calculated by the temperature, a hysteresis strategy is executed. The changed duty cycle is only executed when the hysteresis strategy is satisfied. The hysteresis strategy includes: when the temperature drops to the point of changing the duty cycle, the temperature change is monitored. The hysteresis strategy is only satisfied when the temperature continues to drop or the duration of the changed control duty cycle caused by the temperature drop reaches a set threshold.

[0017] The pre-calibrated speed range corresponding to the resonance of the cooling fan during rapid deceleration is used to identify the control duty cycle range corresponding to the resonance point speed range as the NVH protection duty cycle range. When the cooling fan switches from the operating state to the off state, the relationship between the current control duty cycle and the NVH protection duty cycle range is compared. If the current control duty cycle is less than the minimum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate until it stops. If the current control duty cycle is greater than the maximum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate. When the cooling fan speed is reduced to a high rate until the duty cycle corresponding to the speed falls within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops. If the current control duty cycle is within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops.

[0018] When controlling the cooling fan, if no temperature data is detected or the temperature data is obviously abnormal, the corresponding constant speed duty cycle will be directly activated to control the cooling fan to start.

[0019] When the cooling fan switches from the working state to the off state, the current status of the people in the vehicle and the distance of the user from the vehicle are collected. If the user is in the vehicle, the slow speed reduction of the cooling fan during the shutdown process is controlled according to the slow speed reduction rate of the duty cycle range that is pre-calibrated considering NVH protection. If the user leaves the vehicle, the distance coefficient is obtained based on the distance between the user and the vehicle, and the slow speed reduction rate is corrected by the distance coefficient.

[0020] The advantages of this invention are: it effectively controls the heat dissipation risk of logistics vehicles, while reducing NVH during the control process and improving user experience. A hysteresis strategy is implemented to avoid repeated switching of fan speed control levels, which affects user experience and NVH; a shutdown strategy is implemented to avoid abnormal NVH noise caused by direct shutdown, further improving user experience. Attached Figure Description

[0021] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0022] Figure 1 This is a schematic diagram of the cooling fan control system of the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0024] The cooling fan control strategy provided in this embodiment mainly enables the vehicle controller to control the cooling fan, and to control the cooling fan speed level and NVH-related parameters. The specific solution includes: a control method for the cooling fan of a pure electric logistics vehicle, which includes determining the corresponding working state of the cooling fan based on the current vehicle status data; calculating the current control parameters of the cooling fan based on the collected temperature data of the component to be cooled; and controlling the cooling fan according to the working state and control parameters.

[0025] The control strategy for the cooling fan is integrated into the vehicle controller in software form; the vehicle controller executes the corresponding cooling fan control strategy according to the type of cooling fan to control the operation of the cooling fan.

[0026] Cooling fans include brushless cooling fans and high-speed and low-speed cooling fans. Brushless cooling fans control their speed through duty cycle, while high-speed and low-speed cooling fans control the high and low speed settings by controlling high and low speed relays.

[0027] The vehicle controller can employ a VCU or similar controller. By reusing a second controller within the VCU, the cooling fan can be controlled by the VCU in vehicles without a TMS controller, saving hardware costs. The cooling fan control strategy is integrated into the vehicle controller (VCU). This strategy includes a first control strategy and a second control strategy, corresponding to the control of the brushless cooling fan and high- and low-speed cooling fans, respectively. By integrating both control strategies into the VCU and selecting the appropriate strategy based on actual conditions, the cooling fan can be controlled. This allows a single software development cost to be reused for controlling different types of cooling fans. It can control both high- and low-speed fans as well as brushless fans, significantly reducing design costs, enhancing stability and overall vehicle economy, and improving NVH (noise, vibration, and harshness) issues during brushless fan shutdown.

[0028] This embodiment employs a software algorithm strategy that integrates brushless fan control and high / low speed fan control, offering high compatibility and enabling universal vehicle configuration through simple parameter calibration. The software algorithm strategy effectively solves compatibility issues between different types of fans during development, improving development and calibration efficiency. This algorithm strategy significantly reduces the whistling noise generated by the brushless fan during shutdown, effectively improving the overall vehicle NVH performance.

[0029] like Figure 1As shown, the system collects vehicle switch status data and temperature data into the VCU, which then controls the fan's operating parameters. The system also monitors the power battery status in real time to determine if it is under high voltage. When under high voltage, it collects the temperature of the components to be cooled and the air conditioning request information to determine the corresponding operating state of the cooling fan. The cooling fan's operating state includes both on and off states. When the cooling fan is determined to be on, it collects the temperature data of each component to be cooled in real time, and controls the duty cycle of the brushless cooling fan or the high and low speed parameters of the high and low speed fans based on the temperature data. The control parameters are the closed state of the relays corresponding to the duty cycle and the high and low speed fans.

[0030] A fan control strategy for a pure electric logistics vehicle based on VCU control includes the following steps:

[0031] 1) Collect data on the vehicle's power-on / off status and component temperatures.

[0032] The system collects data on the power battery status to determine if it is in a high-voltage state. If it is, it collects data on the motor controller temperature, motor temperature, DC-DC converter temperature, OBC temperature, and air conditioning requests to determine if the cooling fan needs to be turned on. When the cooling fan is on, it acquires the temperature data of each component to be cooled and determines the corresponding fan control duty cycle based on the temperature of each component. The maximum value of all fan control duty cycles is used as the control duty cycle to drive the brushless cooling fan. Current cooling fan control parameters include the brushless cooling fan's control duty cycle or the high / low speed settings of the high / low speed cooling fan.

[0033] 2) After the entire vehicle is under high voltage, enable the brushless fan using the following strategy:

[0034] 1. Controlling brushless fan speed by judging component temperature (table lookup method), for example:

[0035] When the cooling fan is determined to be in the on state, the temperature data of each component to be cooled is collected in real time. Based on the temperature data, the control duty cycle of the brushless cooling fan or the high and low speed parameters of the high and low speed fans are controlled. When the cooling fan is in the on state, the temperature data of each component to be cooled is acquired, and the corresponding fan control duty cycle is obtained based on the temperature of each component. The maximum value of all fan control duty cycles is taken as the control duty cycle to drive and control the brushless cooling fan.

[0036] The duty cycle of the brushless cooling fan is obtained and controlled by a lookup table method. Temperature data of the components to be cooled is collected, and the control duty cycle corresponding to each component is obtained by looking up the table based on the acquired real-time temperature data. The duty cycles of all components are compared, and the maximum value duty cycle is taken as the control duty cycle of the cooling fan to control the fan, thereby realizing a fan control strategy that meets the heat dissipation requirements.

[0037] 2. When the air conditioner compressor is detected to be running, the fan is controlled at a 60% duty cycle. When the air conditioner compressor is detected to be running, and there is a demand for air conditioning, the cooling fan is controlled at a 60% duty cycle. When the duty cycle for cooling demand is less than 60%, the fan is controlled at a 60% duty cycle. When the duty cycle for cooling demand is greater than 60%, the fan is controlled at the maximum duty cycle.

[0038] 3. When the air conditioner compressor is detected to be running and the medium pressure switch in the three-state pressure switch of the air conditioner is closed, the fan is controlled with a 90% duty cycle.

[0039] 4. A component communication anomaly was detected, prompting a 70% duty cycle to control the fan:

[0040] 3) After the entire vehicle is under high voltage, activate the high and low speed fans according to the following strategy:

[0041] The low-speed fan relay will be enabled if any of the following conditions are met:

[0042] 1. Motor temperature ≥ 75℃;

[0043] 2. MCU controller IGBT temperature ≥ 70℃;

[0044] 3.DCDC body temperature ≥50℃;

[0045] 4. OBC temperature ≥ 50℃;

[0046] 5. The air conditioner compressor is enabled and turned on;

[0047] 6. The VCU detected a communication anomaly in the components;

[0048] The high-speed fan relay will be enabled if any of the following conditions are met:

[0049] 1. Motor temperature ≥ 105℃;

[0050] 2. MCU controller IGBT temperature ≥ 90℃;

[0051] 3.DCDC body temperature ≥60℃;

[0052] 4. OBC temperature ≥ 60℃;

[0053] 5. The air conditioner compressor is enabled and turned on, and the medium-pressure switch in the air conditioner's three-state pressure switch is closed;

[0054] 4) After the cooling fan is turned on, the temperature data is monitored in real time. When the temperature rises and causes a change in the control duty cycle calculated by the temperature, the current control duty cycle is immediately adjusted to the changed control duty cycle. When the temperature drops and causes a change in the control duty cycle calculated by the temperature, a hysteresis strategy is executed. The changed duty cycle is only executed when the hysteresis strategy is met. The hysteresis strategy includes: when the temperature drops to the point of changing the duty cycle, the temperature change is monitored. The hysteresis strategy is only met when the temperature continues to drop or the duration of the changed control duty cycle caused by the temperature drop reaches a set threshold. To prevent the brushless fan speed from becoming unstable or the relay from closing frequently due to rapid temperature jumps caused by the accuracy of the temperature sensor and the temperature of the components, a hysteresis strategy is implemented at all temperature points. For example, as shown in Table 2, when the motor temperature is collected at 45 degrees Celsius, the fan duty cycle is turned on at 30%. If the motor temperature drops to 44 degrees Celsius or 43 degrees Celsius due to stopping or reduced power, the 30% duty cycle is maintained until the motor temperature drops to 42 degrees Celsius, at which point the duty cycle is reduced to 16%. When the motor temperature rises to 45 degrees Celsius again, continue operating the fan with a 30% duty cycle. This temperature hysteresis range can be calibrated based on actual testing. The same principle applies to high-speed and low-speed fans. For example, if the motor temperature reaches 75 degrees Celsius and the low-speed fan is turned on, the low-speed fan can be turned off when the motor temperature drops to 70 degrees Celsius. Similarly, the hysteresis range can be calibrated.

[0055] 5) High / Low Speed ​​Fan and Variable Speed ​​Fan Compatibility Control Strategy: A lookup table strategy is used to control the duty cycle of the variable speed fan based on its temperature point. Since the high and low speed fans only have two speeds, the corresponding operating speeds are fixed, essentially treating it as a brushless fan with only two speeds. Therefore, the duty cycle corresponding to the temperature point can be adjusted to meet the low-speed or high-speed fan activation requirements. Based on this strategy, the temperature point can be directly calibrated according to the vehicle's thermal management requirements, and then the corresponding high-speed or low-speed relay can be activated. This strategy only requires looking up a table, and the calibration value can be modified according to the specific vehicle model requirements.

[0056] 6) Fan Shutdown Strategy: When a vehicle with a brushless fan is powered off, switching directly from a high duty cycle to shutdown will cause the fan to rapidly decelerate. During this process, resonance will generate a high-frequency whistling sound, resulting in poor NVH (Noise, Vibration, and Harshness). To solve this problem, during calibration, the duty cycle range corresponding to the resonance point speed is found. Above this range, the fan decelerates at a relatively fast rate; once it reaches this range, it decelerates at a slower rate; and after passing this range, it decelerates at a faster rate until it stops. These control rates can be calibrated based on the actual vehicle and the fan placement for different vehicle models. The pre-calibrated speed range corresponding to the resonance of the cooling fan during rapid deceleration is used to identify the control duty cycle range corresponding to the resonance point speed range as the NVH protection duty cycle range. When the cooling fan switches from the operating state to the off state, the relationship between the current control duty cycle and the NVH protection duty cycle range is compared. If the current control duty cycle is less than the minimum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate until it stops. If the current control duty cycle is greater than the maximum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate. When the cooling fan speed is reduced to a high rate until the duty cycle corresponding to the speed falls within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops. If the current control duty cycle is within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops.

[0057] When the cooling fan switches from active to off, the system collects data on the current status of occupants and their distance from the vehicle. If the occupant is inside the vehicle, the cooling fan's deceleration during the shutdown process is controlled according to a pre-calibrated slow deceleration rate within the NVH protection duty cycle range. If the occupant leaves the vehicle, a distance coefficient is obtained based on the distance between the occupant and the vehicle, and this coefficient is used to correct the slow deceleration rate. Let K represent the distance coefficient. When someone is inside the vehicle, the distance coefficient is 1. As the occupant gets out of the vehicle and the distance increases while the fan is off, the coefficient K is obtained based on the distance. The coefficient K is proportional to the distance the occupant is away from the vehicle; the greater the distance, the larger the K value. The standard deceleration rate multiplied by K is the corrected deceleration rate. When someone is inside the vehicle, the standard deceleration rate is used to control the deceleration when the engine speed is within the corresponding NVH protection range. When the occupant leaves the vehicle, the impact of noise on the user's NVH can be gradually ignored, so the deceleration rate can be gradually increased by the coefficient K. Therefore, K is proportional to the distance, where K is greater than or equal to 1. When inside the vehicle, it equals 1, and when outside the vehicle, it is greater than 1 and related to the distance. The greater the distance, the larger the value of K, until it reaches the maximum value Kmax. Kmax multiplied by the standard slow deceleration rate equals the maximum deceleration rate when the fan stops. When K reaches Kmax, the value of K remains unchanged. The standard slow deceleration rate can be calibrated according to the actual vehicle, with NVH as the benchmark, so as to maximize the satisfaction of users' NVH needs. When NVH cannot affect users, the speed is reduced as quickly as possible to reduce the waste of energy by the cooling fan.

[0058] 7) Fault handling strategy: If the temperature value of the controller cannot be detected under the high pressure state of the whole vehicle, directly activate the corresponding constant speed duty cycle (the duty cycle of different controllers can be calibrated separately). This requires a large speed to prevent the components from overheating and causing failure due to insufficient heat dissipation.

[0059] Obviously, the specific implementation of this invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A control method for a cooling fan in a pure electric logistics vehicle, characterized in that: This includes determining the operating status of the cooling fan based on the current vehicle status data; and calculating the control parameters of the cooling fan based on the collected temperature data of the components to be cooled. Control the cooling fan according to its operating status and control parameters; The cooling fan control strategy is integrated into the vehicle controller in software form; the vehicle controller executes the corresponding cooling fan control strategy according to the type of cooling fan to control the operation of the cooling fan; the cooling fan control strategy is integrated into the vehicle controller (VCU), and the cooling fan control strategy includes a first control strategy and a second control strategy, which correspond to the control of the brushless cooling fan and the high and low speed cooling fan, respectively. Current control parameters for cooling fans include the control duty cycle of brushless cooling fans or the high and low speed settings of high and low speed cooling fans. After the cooling fan is turned on, the temperature data is monitored in real time. When the temperature rises and causes the control duty cycle to change based on the temperature calculation, the current control duty cycle is immediately adjusted to the changed control duty cycle. When the temperature drops and causes the control duty cycle to change based on the temperature calculation, the hysteresis strategy is executed. The changed duty cycle is only executed when the hysteresis strategy is satisfied. The hysteresis strategy includes: when the temperature drops to the point of duty cycle change, continue to monitor the temperature change, and only satisfy the hysteresis strategy when the temperature continues to drop or the duration of the control duty cycle after the current change caused by the temperature drop reaches a set threshold. The pre-calibrated speed range corresponding to the resonance of the cooling fan during rapid deceleration is used to identify the control duty cycle range corresponding to the resonance point speed range as the NVH protection duty cycle range. When the cooling fan switches from the operating state to the off state, the relationship between the current control duty cycle and the NVH protection duty cycle range is compared. If the current control duty cycle is less than the minimum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate until it stops. If the current control duty cycle is greater than the maximum value of the NVH protection duty cycle range, the fan is decelerated at the fastest rate. When the cooling fan speed is reduced to a high rate until the duty cycle corresponding to the speed falls within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops. If the current control duty cycle is within the NVH protection duty cycle range, the cooling fan is controlled to decrease at a pre-calibrated slow deceleration rate until the control duty cycle is less than the minimum value of the NVH protection duty cycle range, and then the cooling fan is decelerated at the fastest rate until it stops.

2. The control method for a cooling fan of a pure electric logistics vehicle as described in claim 1, characterized in that: The system collects the status of the power battery in real time to determine whether it is under high voltage. When it is under high voltage, it collects the temperature of the components to be cooled and the request information from the air conditioner to determine the corresponding working status of the cooling fan. The working status of the cooling fan includes two states: on and off.

3. The control method for a cooling fan of a pure electric logistics vehicle as described in claim 1, characterized in that: When the cooling fan is determined to be in the on state, the temperature data of each component to be cooled is collected in real time, and the duty cycle of the brushless cooling fan or the high and low speed parameters of the high and low speed fans are controlled based on the temperature data.

4. The control method for a cooling fan of a pure electric logistics vehicle as described in claim 3, characterized in that: When the cooling fan is on, the temperature data of each component to be cooled is acquired, and the corresponding fan control duty cycle is obtained based on the temperature of each component. The maximum value of all fan control duty cycles is taken as the control duty cycle to drive and control the brushless cooling fan.

5. A control method for a cooling fan of a pure electric logistics vehicle as described in any one of claims 1-4, characterized in that: When controlling the cooling fan, if no temperature data is detected or the temperature data is obviously abnormal, the corresponding constant speed duty cycle will be directly activated to control the cooling fan to start.

6. The control method for a cooling fan of a pure electric logistics vehicle as described in claim 1, characterized in that: When the cooling fan switches from the working state to the off state, the current status of the people in the vehicle and the distance of the user from the vehicle are collected. If the user is in the vehicle, the slow speed reduction of the cooling fan during the shutdown process is controlled according to the slow speed reduction rate of the duty cycle range that is pre-calibrated considering NVH protection. If the user leaves the vehicle, the distance coefficient is obtained based on the distance between the user and the vehicle, and the slow speed reduction rate is corrected by the distance coefficient.

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