A control method for a vehicle power battery direct cooling system

Abstract

The present invention provides a control method for a vehicle power battery direct cooling system, which provides multi-dimensional protection for the compressor, covering key functions such as exhaust temperature protection, low pressure protection and pressure ratio protection, and each protection function is designed with multiple intervals. It not only realizes shutdown protection when an abnormality occurs in the compressor, but also introduces three different protection stages: "maintenance interval", "speed reduction interval" and "shutdown protection interval". This can effectively prevent the compressor from operating under extreme working conditions. On the premise of ensuring the safety of the compressor, it can effectively adjust the system operation state, maximize the thermal comfort of the passenger compartment, and avoid discomfort in the vehicle environment caused by compressor shutdown.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a control method for a vehicle power battery direct cooling system. Background Art

[0002] In existing direct cooling systems for vehicle power batteries, the operating status of the compressor is directly related to the overall performance and stability of the system. However, compressor failures are frequent due to issues such as excessive pressure, insufficient pressure, and excessive exhaust temperature. These failures not only seriously affect the thermal management efficiency of the vehicle power battery but can also pose safety risks to the entire vehicle. Summary of the Invention

[0003] In response to the defects in the prior art, the purpose of the present invention is to provide a control method for a vehicle power battery direct cooling system, which provides multi-dimensional protection for the compressor, covering key functions such as exhaust temperature protection, low pressure protection and pressure ratio protection, and each protection function is designed with multiple intervals, thereby effectively preventing the compressor from operating under extreme working conditions, ensuring that the air-conditioning system maintains good durability and stability during long-term use, and improving the reliability and service life of the system.

[0004] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0005] A vehicle power battery direct cooling system control method includes a compressor low pressure protection method, a compression ratio protection method, and a compressor exhaust temperature protection method. Specifically:

[0006] (1) The compressor low-pressure protection method includes:

[0007] If in single cooling mode or air conditioning cooling battery cooling mode: ① When the pressure value is in the first preset maintenance interval, the compressor maintains the current state and does not increase the gear; ② When the pressure value is in the first preset speed reduction interval, the compressor is downgraded, and the reduction value is limited to the first preset interval; ③ When the pressure value is in the first preset shutdown protection interval and the compressor gear is ≤ the preset value and lasts for the first preset time, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the first preset pressure value for normal recovery of low pressure before the compressor can be restarted and controlled normally;

[0008] If in other modes: ① When the pressure value is in the second preset maintenance interval, the compressor maintains the current state and does not shift up; ② When the pressure value is in the second preset speed reduction interval, the compressor shifts down, and the reduction value is limited to the second preset interval; ③ When the pressure value is in the second preset shutdown protection interval, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the second preset pressure value for normal recovery of low pressure before the compressor can be restarted and controlled normally;

[0009] (2) The compression ratio protection method includes: ① when the pressure ratio is in the third preset maintenance interval and lasts for the second preset time, the compressor is maintained in the current state and does not shift up; ② when the pressure ratio is in the third preset speed reduction interval and lasts for the third preset time, the compressor is shifted down, and the reduction value is limited to the range of the third preset interval; ③ when the pressure ratio is in the third preset shutdown protection interval and lasts for the fourth preset time, the compressor is shut down for protection; ④ after the compressor triggers the compression ratio protection shutdown, the pressure ratio must be ≤ the normal recovery compression ratio value and last for the fifth preset time before the compressor can be restarted normally; ⑤ when the pressure ratio is in the hysteresis interval and lasts for the sixth preset time, the compressor is maintained in the previous state, and the hysteresis interval is between the third maintenance interval and the normal recovery compression ratio value, and the previous state refers to the state of the compressor before the pressure ratio enters the hysteresis interval;

[0010] (3) The compressor exhaust temperature protection method includes: ① when the exhaust temperature is in the fourth preset maintenance interval, the compressor is maintained in the current state and the gear is not increased; ② when the exhaust temperature is in the fourth preset speed reduction interval, the compressor is downgraded, and the reduction value is limited to the range of the fourth preset interval; ③ when the exhaust temperature is in the fourth preset shutdown protection period and lasts for the seventh preset time, the compressor is shut down for protection; ④ after the compressor triggers the exhaust temperature protection shutdown, the compressor can only be restarted and controlled normally when the exhaust temperature is less than the normal recovery exhaust temperature value.

[0011] Preferably, for the compressor low pressure protection method:

[0012] If in single cooling mode or air conditioning cooling battery cooling mode: ① When the pressure value is in the first preset maintenance range, i.e. [220, 240) kPa, the compressor maintains the current state and does not increase the gear; ② When the pressure value is in the first preset speed reduction range, i.e. [80, 220) kPa, the compressor is downgraded, and the reduction value is limited to the first preset range, i.e. [1, 10]; ③ When the pressure value is in the first preset shutdown protection range, i.e. <155 kPa, and the compressor gear is ≤ the preset value, i.e. 2, and lasts for the first preset time, i.e. 1 minute, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the first preset pressure value of 224 kPa for the low pressure to recover normally before the compressor can be restarted and controlled normally;

[0013] If in other modes: ① When the pressure value is in the second preset maintenance interval, i.e. [260,280) kPa, the compressor maintains the current state and does not shift up; ② When the pressure value is in the second preset speed reduction interval, i.e. [80,260) kPa, the compressor shifts down, and the reduction value is limited to the second preset interval range, i.e. [1,10]; ③ When the pressure value is in the second preset shutdown protection interval, i.e. <80 kPa, the compressor is shut down for protection; ④ After the compressor triggers the low-pressure protection shutdown, it must reach the second preset pressure value of 228 kPa for normal recovery of the low pressure before the compressor can be restarted and controlled normally.

[0014] Preferably, for the compressor low-pressure protection method, when the compressor is downshifted, the calculation formula for the reduction value is: reduction value = (downshift protection pressure value - current low pressure) / F, where F is the calibration quantity, and the downshift protection pressure value is the maximum value of the downshift protection pressure value range; when in single cooling mode or air-conditioning cooling battery cooling mode, F = 20; when in other modes, F = 2.

[0015] Preferably, for the compression ratio protection method:

[0016] ① When the pressure ratio is in the third preset maintenance interval, i.e., [10, 11], and lasts for the second preset time, i.e., 10s, the compressor maintains the current state and does not shift up; ② When the pressure ratio is in the third preset speed reduction interval, i.e., (11, 12], and lasts for the third preset time, i.e., 10s, the compressor is shifted down, and the reduction value is limited to the third preset interval range, i.e., [1, 10]; ③ When the pressure ratio is in the third preset shutdown protection interval, i.e., >12, and lasts for the fourth preset time, i.e., 5s, the compressor is shut down for protection; ④ After the compressor triggers the compression ratio protection shutdown, the compression ratio must be ≤ the normal recovery compression ratio, i.e., 8, and lasts for the fifth preset time, i.e., 5s, before the compressor can be restarted and controlled normally; ⑤ When the pressure ratio is in the hysteresis interval, i.e., (8, 10), and lasts for the sixth preset time, i.e., 5s, the compressor is maintained in the previous state.

[0017] Preferably, for the compression ratio protection method, when the compressor is downshifted, the calculation formula of the reduction value is: reduction value = (current compression ratio - 11) / 3.

[0018] Preferably, for the compressor exhaust temperature protection method:

[0019] ① When the exhaust temperature is in the fourth preset maintenance interval, i.e. [105,115)℃, the compressor maintains the current state and does not shift up; ② When the exhaust temperature is in the fourth speed reduction interval, i.e. [115,+∞)℃, the compressor shifts down, and the reduction value is limited to the fourth preset interval range, i.e. [1,10]; ③ When the exhaust temperature is in the fourth preset shutdown protection period, i.e. ≥120℃ and lasts for the seventh preset time, i.e. 20s, the compressor is shut down for protection; ④ After the compressor triggers the exhaust temperature protection shutdown, the compressor can only be restarted and controlled normally when the exhaust temperature is less than the normal recovery exhaust temperature value, i.e. 105℃.

[0020] Preferably, for the compressor exhaust temperature protection method, when the compressor is downshifted, the calculation formula for the reduction value is: (exhaust temperature-downshift protection exhaust temperature value) / 5.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The control method for a vehicle power battery direct cooling system provided by this invention provides multi-dimensional compressor protection, encompassing key functions such as high-voltage protection, low-voltage protection, and pressure ratio protection. These comprehensive protection measures effectively prevent the compressor from operating under extreme operating conditions, ensuring the air conditioning system maintains excellent durability and stability during long-term use, thereby improving the system's reliability and service life.

[0023] 2. The control method for a vehicle power battery direct cooling system provided by this invention primarily addresses compressor failure issues in vehicle power battery direct cooling systems, such as low compressor pressure and high exhaust temperature. Furthermore, while protecting the compressor, this invention also effectively addresses passenger compartment thermal comfort, minimizing cabin temperature fluctuations and user complaints caused by compressor shutdown protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0025] Figure 1 This is the overall logical framework diagram of the vehicle power battery direct cooling system control method described in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0027] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0028] Furthermore, in this application, descriptions involving "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0029] This embodiment provides a control method for a vehicle power battery direct cooling system, which aims to solve problems such as low compressor pressure and high compressor exhaust temperature in the vehicle power battery direct cooling system, thereby improving the durability of the compressor and reducing the failure rate. Figure 1 Shown, including:

[0030] 1. Compressor Low-Pressure Protection Method: When the compressor low-pressure is too low, it indicates that the system or compressor operating environment is relatively harsh. To address this issue, a protection strategy is proposed, which includes dividing the operating range into different ranges, namely the maintenance range, the speed reduction range, and the shutdown protection range, to ensure the safe operation of the system under low-pressure conditions. Specifically, the protection method is described below using specific numerical values, as shown in Table 1:

[0031] (1) When in cooling mode only or air conditioning cooling battery cooling mode:

[0032] ① When the pressure value is in the first preset maintenance range, i.e. [220, 240) kPa, the compressor maintains the current state and does not shift up;

[0033] ② When the pressure value is in the first preset speed reduction range, i.e., [80, 220) kPa, the compressor is downshifted. The calculation formula of the downshift value is: downshift value = (downshift protection pressure value - current low pressure) / F, where F = 20. The downshift protection pressure value is the maximum value of the downshift protection pressure value range, i.e., 220 kPa, and the downshift value is limited to the first preset range, i.e., [1, 10].

[0034] ③ When the pressure value is in the first preset shutdown protection range, i.e. <155kPa, and the compressor gear is ≤ the preset value, i.e. 2, and lasts for the first preset time, i.e. 1min, the compressor will be shut down for protection;

[0035] ④ After the compressor triggers the low-pressure protection shutdown, the compressor can only be restarted and controlled normally when the low-pressure pressure reaches the first preset pressure value of 224kPa for normal recovery.

[0036] If in other modes (i.e., other than cooling-only mode and air conditioning cooling and battery cooling mode), then:

[0037] ① When the pressure value is in the second preset maintenance range, i.e. [260,280) kPa, the compressor maintains the current state and does not shift up;

[0038] ② When the pressure value is in the second preset speed reduction range, i.e., [80, 260) kPa, the compressor is downshifted. The calculation formula of the downshift value is: downshift value = (downshift protection pressure value - current low pressure) / F, where F = 2. The downshift protection pressure value is the maximum value of the downshift protection pressure value range, i.e., 260 kPa here. The downshift value is limited to the second preset range, i.e., [1, 10].

[0039] ③ When the pressure value is in the second preset shutdown protection range, i.e. <80kPa, the compressor will be shut down for protection;

[0040] ④ After the compressor triggers the low-pressure protection shutdown, the compressor can only be restarted and controlled normally when the low-pressure recovery reaches the second preset pressure value of 228kPa.

[0041] Table 1

[0042]

[0043] 2. Compression Ratio Protection Method: To prevent the compression ratio of the compressor from exceeding the limit during operation, this application proposes a protection strategy that divides the compressor into a maintenance interval, a speed reduction interval, and a shutdown protection interval to ensure that the compressor operates within the compression ratio range to prevent failure or damage caused by an excessively high compression ratio. Specifically, the protection method is described below using specific numerical values, as shown in Table 2:

[0044] ① When the pressure ratio is in the third preset maintenance interval, i.e., [10, 11], and lasts for the second preset time, i.e., 10s, the compressor maintains the current state and does not shift up;

[0045] ② When the pressure ratio is in the third preset speed reduction interval (11, 12) and lasts for the third preset time (10s), the compressor is downshifted. The calculation formula of the downshift value is: downshift value = (current pressure ratio - 11) / 3, and the downshift value is limited to the third preset interval range (1, 10);

[0046] ③ When the pressure ratio is in the third preset shutdown protection range, i.e., >12, and lasts for the fourth preset time, i.e., 5s, the compressor will be shut down for protection;

[0047] ④ After the compressor triggers the compression ratio protection shutdown, the compression ratio must be ≤ the normal recovery compression ratio, i.e. 8, and last for the fifth preset time, i.e. 5s, before the compressor can be restarted and controlled normally;

[0048] ⑤ When the pressure ratio is in the hysteresis interval (8, 10) and lasts for the sixth preset time, that is, 5s, the compressor is maintained in the previous state, which refers to the state of the compressor before the pressure ratio enters the hysteresis interval.

[0049] Table 2

[0050]

[0051] 3. Compressor Exhaust Temperature Protection Method: When the compressor exhaust temperature is too high, this temperature protection strategy is proposed to prevent carbonization of the refrigerant oil due to excessive temperature or damage to the compressor materials due to excessive temperature. This strategy is also divided into a maintenance interval, a speed reduction interval, and a shutdown protection interval to ensure the normal operation of the compressor and extend its service life. Specifically, the following describes this protection method using specific values, as shown in Table 3:

[0052] ① When the exhaust temperature is in the fourth preset maintenance range, i.e. [105,115)°C, the compressor maintains the current state and does not shift up;

[0053] ② When the exhaust temperature is in the fourth speed reduction range, i.e. [115, +∞)°C, the compressor is downshifted. The downshift value is calculated as follows: downshift value = (exhaust temperature - downshift protection exhaust temperature value) / 5. The downshift value is limited to the fourth preset range, i.e. [1, 10].

[0054] ③ When the exhaust temperature is within the fourth preset shutdown protection period, i.e. ≥120°C, and lasts for the seventh preset time, i.e. 20s, the compressor will be shut down for protection;

[0055] ④ After the compressor triggers the exhaust temperature protection shutdown, the exhaust temperature must be lower than the normal recovery exhaust temperature value, i.e. 105℃, before the compressor can be restarted and controlled normally.

[0056] Table 3

[0057]

[0058] The vehicle power battery direct cooling system control method provided in this embodiment not only implements shutdown protection when an abnormality occurs in the compressor, but also introduces three different protection stages: "maintenance interval", "speed reduction interval" and "shutdown protection interval". This innovative design can effectively adjust the system operation state while ensuring the safety of the compressor, maximize the thermal comfort of the passenger compartment, and avoid discomfort in the vehicle environment caused by compressor shutdown. Therefore, through the aforementioned protection strategy, the failure rate of the compressor is effectively reduced, its durability is improved, and the overall performance and reliability of the vehicle power battery direct cooling system are improved. In addition, the vehicle power battery direct cooling system control method provided in this embodiment, in the direct cooling system cooling mode, when the system load is too large or the refrigerant leaks, optimizes the refrigeration by controlling the compressor speed to solve the problem of poor working boundaries of the compressor due to high refrigerant pressure / refrigerant temperature, thereby reducing the failure rate of the compressor.

[0059] It should be noted that the specific values ​​provided in this embodiment are merely examples. In actual use, the values ​​may vary depending on the vehicle model and application scenario. Experimental verification has shown that the present invention can effectively reduce the maximum system pressure from 3200 kPa to 2600 kPa and the maximum compressor exhaust temperature from 140°C to 115°C.

[0060] The above describes the specific embodiments of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of this invention.

Claims

1. A vehicle power battery direct cooling system control method, characterized in that: Including compressor low pressure protection method, compression ratio protection method, compressor exhaust temperature protection method, specifically: (1) The compressor low-pressure protection method includes: If in single cooling mode or air conditioning cooling battery cooling mode: ① When the pressure value is in the first preset maintenance interval, the compressor maintains the current state and does not increase the gear; ② When the pressure value is in the first preset speed reduction interval, the compressor is downgraded, and the reduction value is limited to the first preset interval; ③ When the pressure value is in the first preset shutdown protection interval and the compressor gear is ≤ the preset value and lasts for the first preset time, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the first preset pressure value for normal recovery of low pressure before the compressor can be restarted and controlled normally; If in other modes: ① When the pressure value is in the second preset maintenance interval, the compressor maintains the current state and does not shift up; ② When the pressure value is in the second preset speed reduction interval, the compressor shifts down, and the reduction value is limited to the second preset interval; ③ When the pressure value is in the second preset shutdown protection interval, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the second preset pressure value for normal recovery of low pressure before the compressor can be restarted and controlled normally; (2) The compression ratio protection method includes: ① when the pressure ratio is in the third preset maintenance interval and lasts for the second preset time, the compressor is maintained in the current state and does not shift up; ② when the pressure ratio is in the third preset speed reduction interval and lasts for the third preset time, the compressor is shifted down, and the reduction value is limited to the range of the third preset interval; ③ when the pressure ratio is in the third preset shutdown protection interval and lasts for the fourth preset time, the compressor is shut down for protection; ④ after the compressor triggers the compression ratio protection shutdown, the pressure ratio must be ≤ the normal recovery compression ratio value and last for the fifth preset time before the compressor can be restarted normally; ⑤ when the pressure ratio is in the hysteresis interval and lasts for the sixth preset time, the compressor is maintained in the previous state, and the hysteresis interval is between the third maintenance interval and the normal recovery compression ratio value, and the previous state refers to the state of the compressor before the pressure ratio enters the hysteresis interval; (3) The compressor exhaust temperature protection method includes: ① when the exhaust temperature is in the fourth preset maintenance interval, the compressor is maintained in the current state and the gear is not increased; ② when the exhaust temperature is in the fourth preset speed reduction interval, the compressor is downgraded, and the reduction value is limited to the range of the fourth preset interval; ③ when the exhaust temperature is in the fourth preset shutdown protection period and lasts for the seventh preset time, the compressor is shut down for protection; ④ after the compressor triggers the exhaust temperature protection shutdown, the compressor can only be restarted and controlled normally when the exhaust temperature is less than the normal recovery exhaust temperature value.

2. The vehicle power battery direct cooling system control method according to claim 1, characterized in that: Low pressure protection method for compressor: If in single cooling mode or air conditioning cooling battery cooling mode: ① When the pressure value is in the first preset maintenance range, i.e. [220, 240) kPa, the compressor maintains the current state and does not increase the gear; ② When the pressure value is in the first preset speed reduction range, i.e. [80, 220) kPa, the compressor is downgraded, and the reduction value is limited to the first preset range, i.e. [1, 10]; ③ When the pressure value is in the first preset shutdown protection range, i.e. <155 kPa, and the compressor gear is ≤ the preset value, i.e. 2, and lasts for the first preset time, i.e. 1 minute, the compressor is shut down for protection; ④ After the compressor triggers the low pressure protection shutdown, it must reach the first preset pressure value of 224 kPa for the low pressure to recover normally before the compressor can be restarted and controlled normally; If in other modes: ① When the pressure value is in the second preset maintenance interval, i.e. [260,280) kPa, the compressor maintains the current state and does not shift up; ② When the pressure value is in the second preset speed reduction interval, i.e. [80,260) kPa, the compressor shifts down, and the reduction value is limited to the second preset interval range, i.e. [1,10]; ③ When the pressure value is in the second preset shutdown protection interval, i.e. <80 kPa, the compressor is shut down for protection; ④ After the compressor triggers the low-pressure protection shutdown, it must reach the second preset pressure value of 228 kPa for normal recovery of the low pressure before the compressor can be restarted and controlled normally.

3. The vehicle power battery direct cooling system control method according to claim 2, characterized in that: For the compressor low-pressure protection method, when the compressor is downshifted, the calculation formula for the reduction value is: reduction value = (downshift protection pressure value - current low pressure) / F, where F is the calibration quantity, and the downshift protection pressure value is the maximum value of the downshift protection pressure value range; when in single cooling mode or air-conditioning cooling battery cooling mode, F = 20; when in other modes, F = 2.

4. The vehicle power battery direct cooling system control method according to claim 1, characterized in that: Compression ratio protection method: ① When the pressure ratio is in the third preset maintenance interval, i.e., [10, 11], and lasts for the second preset time, i.e., 10s, the compressor maintains the current state and does not shift up; ② When the pressure ratio is in the third preset speed reduction interval, i.e., (11, 12], and lasts for the third preset time, i.e., 10s, the compressor is shifted down, and the reduction value is limited to the third preset interval range, i.e., [1, 10]; ③ When the pressure ratio is in the third preset shutdown protection interval, i.e., >12, and lasts for the fourth preset time, i.e., 5s, the compressor is shut down for protection; ④ After the compressor triggers the compression ratio protection shutdown, the compression ratio must be ≤ the normal recovery compression ratio, i.e., 8, and lasts for the fifth preset time, i.e., 5s, before the compressor can be restarted and controlled normally; ⑤ When the pressure ratio is in the hysteresis interval, i.e., (8, 10), and lasts for the sixth preset time, i.e., 5s, the compressor is maintained in the previous state.

5. The vehicle power battery direct cooling system control method according to claim 4, characterized in that: For the compression ratio protection method, when the compressor is downshifted, the calculation formula of the reduction value is: reduction value = (current compression ratio - 11) / 3.

6. The vehicle power battery direct cooling system control method according to claim 1, characterized in that: Compressor exhaust temperature protection method: ① When the exhaust temperature is in the fourth preset maintenance interval, i.e. [105,115)℃, the compressor maintains the current state and does not shift up; ② When the exhaust temperature is in the fourth speed reduction interval, i.e. [115,+∞)℃, the compressor shifts down, and the reduction value is limited to the fourth preset interval range, i.e. [1,10]; ③ When the exhaust temperature is in the fourth preset shutdown protection period, i.e. ≥120℃ and lasts for the seventh preset time, i.e. 20s, the compressor is shut down for protection; ④ After the compressor triggers the exhaust temperature protection shutdown, the compressor can only be restarted and controlled normally when the exhaust temperature is less than the normal recovery exhaust temperature value, i.e. 105℃.

7. The vehicle power battery direct cooling system control method according to claim 6, characterized in that: For the compressor exhaust temperature protection method, when the compressor is downshifted, the reduction value is calculated as: (exhaust temperature - downshift protection exhaust temperature value) / 5.

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