Vehicle power battery direct cooling system control method

Abstract

According to the vehicle power battery direct cooling system control method, multi-dimensional protection is carried out on the compressor, key functions such as exhaust temperature protection, low-pressure protection and pressure ratio protection are covered, multi-interval design is carried out on each protection function, shutdown protection is achieved when the compressor is abnormal, and the service life of the compressor is prolonged. And three different protection stages of a maintenance interval, a speed reduction interval and a shutdown protection interval are introduced, so that the compressor can be effectively prevented from running under the limiting working condition, the running state of the system can be effectively adjusted on the premise of ensuring the safety of the compressor, the thermal comfort of a passenger compartment is ensured to the greatest extent, and the service life of the passenger compartment is prolonged. And uncomfortable environment in the vehicle caused by shutdown of the compressor is avoided.

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 the existing direct cooling system of vehicle power batteries, the operating status of the compressor is directly related to the overall performance and stability of the system. However, due to problems such as excessive pressure, low pressure and high exhaust temperature, compressor failures occur frequently. These failures not only seriously affect the thermal management efficiency of the vehicle power battery, but may also cause safety hazards in the operation of the entire vehicle. Summary of the invention

[0003] In view of 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 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 invention object, the present invention adopts the following technical scheme:

[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 comprises:

[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 position; 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 position ≤ 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, the compressor can only be restarted and controlled normally when the low pressure is restored to the first preset pressure value;

[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, the compressor can only be restarted and controlled normally when the low pressure is restored to the second preset pressure value;

[0009] (2) The compression ratio protection method includes: ① when the compression 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 compression 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 compression 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 compressor can be restarted normally only when the pressure ratio is ≤ the normal recovery compression ratio value and lasts for the fifth preset time; 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, 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 maintains the current state and does not increase the gear; 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 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 interval, i.e. [220,240) kPa, the compressor maintains the current state and does not increase the gear position; ② When the pressure value is in the first preset speed reduction interval, i.e. [80,220) kPa, the compressor is downgraded, and the reduction value is limited to the first preset interval range, i.e. [1,10]; ③ When the pressure value is in the first preset shutdown protection interval, i.e. <155 kPa, and the compressor gear position is ≤ the preset value, i.e. 2, and lasts for the first preset time, i.e. 1 min, 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 the 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 a 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 downshifted, 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 vehicle power battery direct cooling system control method provided by the present invention provides multi-dimensional protection for the compressor, covering key functions such as high-voltage protection, low-voltage protection, and pressure ratio protection. Through these comprehensive protection measures, the compressor can be effectively prevented from operating under extreme conditions, ensuring that the air-conditioning system maintains good durability and stability during long-term use, thereby improving the reliability and service life of the system.

[0023] 2. The vehicle power battery direct cooling system control method provided by the present invention mainly solves the compressor failure problem caused by too low compressor pressure and too high exhaust temperature in the vehicle power battery direct cooling system. At the same time, on the basis of protecting the compressor, the present invention also effectively takes into account the thermal comfort of the passenger compartment, and minimizes the temperature fluctuations and user complaints caused by the compressor shutdown protection. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 1 This is an 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 which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0028] Furthermore, in the present 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 the problems of too low compressor pressure and too high compressor exhaust temperature in the vehicle power battery direct cooling system, so as to improve the durability of the compressor and reduce the failure rate. Figure 1 As shown, including:

[0030] 1. Compressor low pressure protection method: When the compressor low pressure is too low, it indicates that the operating environment of the system or compressor is relatively bad. To address this problem, this protection strategy is proposed, including dividing different operating intervals, namely, the maintenance interval, the speed reduction interval and the shutdown protection interval, to ensure the safe operation of the system under low pressure. Specifically, the following describes the protection method through specific 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 interval, 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 interval, i.e., [80, 220) kPa, the compressor is downshifted, and the calculation of the downshift value is as follows: downshift value = (downshift protection pressure value - current low pressure) / F, where F = 20, and 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 interval, i.e., [1, 10];

[0034] ③ When the pressure value is in the first preset shutdown protection interval, i.e., <155kPa, and the compressor gear position 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. not cooling mode only and air conditioning cooling battery cooling mode), then:

[0037] 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;

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

[0039] ③ When the pressure value is in the second preset shutdown protection interval, 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 pressure reaches the second preset pressure value of 228kPa for normal recovery.

[0041] Table 1

[0042]

[0043] 2. Compression ratio protection method: In order to prevent the compression ratio of the compressor from exceeding the limit value during operation, this application proposes this protection strategy, which divides the maintenance interval, the speed reduction interval and the 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 through specific 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 is maintained in the current state without shifting 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, and the calculation formula of the reduction value is: reduction value = (current pressure ratio - 11) / 3, and the reduction value is limited to the third preset interval range (1, 10);

[0046] 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;

[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, and the previous state 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, in order to avoid carbonization of the refrigeration oil due to excessive temperature, or damage to the compressor material due to excessive temperature, this temperature protection strategy is proposed. 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 the protection method through specific values, as shown in Table 3:

[0052] ① When the exhaust temperature is in the fourth preset maintenance interval, 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 interval, i.e., [115, +∞)°C, the compressor is downshifted. The calculation formula for the reduction value is: reduction value = (exhaust temperature - downshift protection exhaust temperature value) / 5. The reduction value is limited to the fourth preset interval 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 compressor can only be restarted and controlled normally when the exhaust temperature is less than the normal recovery exhaust temperature value, i.e. 105°C.

[0056] Table 3

[0057]

[0058] The vehicle power battery direct cooling system control method provided in this embodiment not only realizes shutdown protection when the compressor is abnormal, 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 under the premise of ensuring the safety of the compressor, maximize the thermal comfort of the passenger compartment, and avoid the discomfort of the vehicle environment caused by compressor shutdown. Therefore, through the aforementioned protection strategy, the failure rate of the compressor is effectively reduced, and its durability is improved, thereby improving the overall performance and reliability of the vehicle power battery direct cooling system. In addition, the vehicle power battery direct cooling system control method provided in this embodiment, when the system load is too large or the refrigerant leaks in the refrigeration mode of the direct cooling system, 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 only a preferred example. When the technical solution is actually used, the selection of values ​​may vary for different vehicle models and application scenarios. Through experimental verification, the present invention can effectively reduce the maximum system pressure by 3200kpa->2600kpa and reduce the maximum exhaust temperature of the compressor by 140℃->115℃.

[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 technical concept of the present 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 comprises: 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 position; 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 position ≤ 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, the compressor can only be restarted and controlled normally when the low pressure is restored to the first preset pressure value; 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, the compressor can only be restarted and controlled normally when the low pressure is restored to the second preset pressure value; (2) The compression ratio protection method includes: ① when the compression 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 compression 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 compression 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 compressor can be restarted normally only when the pressure ratio is ≤ the normal recovery compression ratio value and lasts for the fifth preset time; 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, 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 maintains the current state and does not increase the gear; 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 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 interval, i.e. [220,240) kPa, the compressor maintains the current state and does not increase the gear position; ② When the pressure value is in the first preset speed reduction interval, i.e. [80,220) kPa, the compressor is downgraded, and the reduction value is limited to the first preset interval range, i.e. [1,10]; ③ When the pressure value is in the first preset shutdown protection interval, i.e. <155 kPa, and the compressor gear position is ≤ the preset value, i.e. 2, and lasts for the first preset time, i.e. 1 min, 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 the 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 downshifted, 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 for 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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