Diesel engine output power control method and system based on battery SOC

Abstract

The invention discloses a diesel engine output power control method and system based on a battery SOC, and the method comprises the steps: obtaining various parameters of a hybrid vehicle, constructing a three-level decision logic, and obtaining a current diesel engine target output power interval through the three-level decision logic; the current target output power interval of the diesel engine is sent to a diesel engine controller, the diesel engine controller is adjusted according to the current target output power interval of the diesel engine, and the actual output power of the diesel engine is controlled within the current target output power interval of the diesel engine; the actual output power of the diesel engine and the current exhaust temperature of the diesel engine are collected at specific intervals, and if the actual output power of the diesel engine exceeds the specific range of the current target output power interval of the diesel engine or the current exhaust temperature of the oil extraction machine exceeds the specific range of the pre-obtained aftertreatment optimal temperature interval, the diesel engine is started; and recalculating the target output power interval of the diesel engine. The system can overcome the defects of low temperature, poor tail gas conversion efficiency and high fuel oil consumption of a diesel engine tail gas after-treatment system.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle power control technology, and in particular to a method and system for controlling the output power of a diesel engine based on battery SOC. Background Technology

[0002] Currently, most hybrid vehicles use the power battery as a reservoir for "peak shaving and valley filling": under high load conditions, the power battery and diesel engine jointly output power; under low load conditions, the diesel engine powers the drive system while simultaneously charging the power battery to maintain battery charge balance. However, this strategy has the following significant technical drawbacks: (1) The temperature of the diesel engine exhaust aftertreatment system is too low, resulting in low exhaust gas conversion efficiency: After the power battery assumes part of the load adjustment, the diesel engine often operates in the low to medium power range, and the exhaust temperature is difficult to reach the optimal operating temperature (250-400℃) of the exhaust aftertreatment system (SCR, DPF). When the exhaust temperature is below 250℃, the activity of the SCR system catalyst decreases significantly, the oxidation rate of DPF particles decreases, and particulate matter is easily accumulated and blocked, requiring frequent active regeneration, which further increases fuel consumption and drive system wear. The conditions for complete combustion of diesel are high temperature and rich oxygen. When the temperature is low, the activity of the heavy metal catalyst in the aftertreatment is weak, resulting in the incomplete combustion of hydrocarbon particles in the exhaust gas, which are absorbed by the particulate filter (DPF). Over time, this will cause DPF blockage and poor engine exhaust, so active regeneration is required to burn off the particles adsorbed by the DPF. (2) Diesel engine operating point deviates from the optimal economic range, resulting in high fuel consumption: The fuel consumption rate of diesel engines is relatively high in the low-to-medium power range (20%-30% of rated power). Simultaneously, when the power battery SOC is high (e.g., exceeding 80%), in order to meet the battery's "shallow charge and discharge" protection requirements, the diesel engine's charging power needs to be limited. This causes the diesel engine to frequently switch operating points when the load fluctuates, further deviating from the optimal economic range, and significantly increasing the vehicle's overall fuel consumption. The diesel engine operating point refers to the operating state at the current speed and output torque.

[0003] In existing technologies, solutions for diesel engine control in hybrid vehicles mostly focus on power source switching logic or SOC maintenance strategies, such as controlling diesel engine start-stop by setting a fixed SOC threshold. However, these solutions fail to coordinate and couple the SOC state of the power battery, external operating load, and the temperature requirements of the diesel engine's exhaust aftertreatment system. Some solutions attempt to increase exhaust temperature by adjusting the diesel engine's fuel injection quantity, but without dynamic optimization based on actual load requirements, this can easily lead to contradictions such as "sacrificing fuel consumption for temperature increase" or "giving up emissions for fuel saving," failing to achieve coordinated optimization of multiple objectives. Summary of the Invention

[0004] The purpose of this invention is to provide a diesel engine output power control method and system based on battery SOC. The method divides the power battery SOC value into different ranges to determine the initial range of the target output power of the diesel engine. This initial range is then corrected using external operating load parameters. Finally, power compensation is performed on the corrected power range using exhaust aftertreatment parameters to obtain the final target output power of the diesel engine. This achieves a dual optimization effect on diesel engine fuel consumption and exhaust gas treatment. This invention is implemented through the following technical solutions.

[0005] In a first aspect, the present invention provides a diesel engine output power control method based on battery SOC, comprising the following steps: Acquire multiple parameters of the hybrid vehicle; wherein, the multiple parameters include power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust aftertreatment parameters; A three-level decision logic is constructed based on multiple parameters of the hybrid vehicle, and the target output power range of the current diesel engine is obtained through the three-level decision logic. The hybrid vehicle controller sends the current target output power range of the diesel engine to the diesel engine controller, so that the diesel engine controller can adjust the actual output power of the diesel engine according to the current target output power range, and control the actual output power of the diesel engine within the current target output power range. The actual output power and current exhaust temperature of the diesel engine are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range or the current exhaust temperature of the oil pump exceeds a specific range of the pre-acquired optimal after-treatment temperature range, the target output power range of the diesel engine is recalculated.

[0006] Optionally, the power battery parameters include the current SOC value SOC_current, the maximum allowable charging power P_charge_max and the maximum allowable discharging power P_discharge_max of the power battery at the current cell temperature; The external operating condition load parameters include the hybrid vehicle's current requested power P_load; The diesel engine parameters include the current output power P_engine_actual and the optimal fuel economy power range P_engine_eco. You can directly refer to the universal characteristic curve of this engine model.

[0007] The exhaust gas aftertreatment parameters include the minimum sustained aftertreatment temperature power of the diesel engine P_engine_min_temp and the current exhaust temperature of the oil pumping unit T_exh_actual.

[0008] In this invention, the optimal fuel economy power range P_engine_eco for the diesel engine is calibrated through bench testing, with an empirical value taken as 60% of the diesel engine's rated power. The minimum sustained aftertreatment temperature power P_engine_min_temp for the diesel engine is also calibrated through bench testing to ensure that the diesel engine's exhaust temperature is ≥250℃.

[0009] Optionally, the construction of the three-level decision logic includes constructing a first-level SOC state classification decision based on the power battery parameters, constructing a second-level dynamic correction classification decision based on the external operating condition load parameters, and constructing a third-level after-treatment temperature and power feedback compensation classification decision based on the exhaust gas after-treatment parameters. The first-level SOC state classification decision includes dividing the current SOC value into a low SOC range, a medium SOC range, and a high SOC range based on the range of the current SOC value; the second-level operating condition load dynamic correction classification decision includes the relationship between the vehicle's current requested power and the first range boundary of the diesel engine's target output power; the third-level after-treatment temperature power feedback compensation classification decision includes the relationship between the oil pumping unit's current exhaust temperature and the optimal after-treatment temperature range, where the optimal after-treatment temperature range is 250℃-400℃.

[0010] Optionally, obtaining the current target output power range of the diesel engine through the three-level decision logic includes defining the first range of the target output power of the diesel engine based on the first-level SOC state classification decision. The first range of the target output power of the diesel engine is modified according to the dynamic correction and hierarchical decision of the second-level operating condition load to obtain the second range of the target output power of the diesel engine. Based on the third-level after-processing temperature and power feedback compensation hierarchical decision, power compensation is performed on the second range of the target output power of the diesel engine to obtain the current target output power range of the diesel engine.

[0011] Optionally, when SOC_current ≤ 20%, SOC_current belongs to the low SOC range. In the low SOC range, the lower limit of the target output power of the diesel engine, P_engine_target_low1, is calculated using the following formula: P_engine_target_low1=P_load + P_charge_req, In the formula, P_charge_req represents the required charging power of the power battery, which is calculated using the following formula: P_charge_req=k×(SOC_target - SOC_current), Where k is the charging power coefficient, which is corrected according to the temperature of the power battery, SOC_target is the target SOC value, set to 80% in the present invention, and P_engine_target_low1 ≥ P_engine_min_temp; SOC is a professional term, state of charge, referring to the remaining power percentage of the battery at present. The target SOC value is defined as 80%, that is, during the vehicle operation, the SOC value fluctuates around 80% as much as possible, so that the large-power shallow charge and shallow discharge mode of the battery can be better utilized.

[0012] The upper limit of the diesel engine target output power P_engine_target_high1 = the upper limit of P_engine_eco. Optionally, when 20% < SOC_current < 80%, SOC_current belongs to the medium SOC interval. In the medium SOC interval, the lower limit of the diesel engine target output power P_engine_target_low2 is obtained by the following formula: P_engine_target_low2 = P_engine_min_temp, The upper limit of the diesel engine target output power P_engine_target_high2 is obtained by the following formula: P_engine_target_high2 = the upper limit of P_engine_eco, and P_engine_target_high2 ≤ P_load + P_charge_max.

[0013] Optionally, when SOC_current ≥ 80%, SOC_current belongs to the high SOC interval. In the high SOC interval, the lower limit of the diesel engine target output power P_engine_target_low3 is obtained by the following formula: P_engine_target_low3 = P_engine_min_temp, The upper limit of the diesel engine target output power P_engine_target_high3 is obtained by the following formula: P_engine_target_high3 = P_load + P_charge_limit, Where P_charge_limit is the maximum allowable charging power of the power battery in the high SOC interval. In the present invention, P_charge_limit is set to 20% of P_charge_max to avoid overcharging of the power battery.

[0014] Optionally, the second interval of the diesel engine target output power includes: When P_load > P_engine_target_high_i, where i ranges from 1 to 3, representing the upper limits of the diesel engine target output power in the low SOC interval, medium SOC interval, and high SOC interval respectively, the upper limit P_engine_target_high' of the second interval of the diesel engine target output power is obtained by correcting through the following formula: P_engine_target_high' = P_load + P_charge_max Or P_engine_target_high' = P_load + P_charge_limit, and P_engine_target_high' ≤ the rated power of the diesel engine; (to avoid over-power operation).

[0015] When P_load < P_engine_target_low_i, where i ranges from 1 to 3, representing the lower limits of the diesel engine target output power in the low SOC interval, medium SOC interval, and high SOC interval respectively, the lower limit of the second interval of the diesel engine target output power is obtained by correcting through the following formula: P_engine_target_low' = P_engine_min_temp.

[0016] Optionally, the current diesel engine target output power interval includes: If T_exh_actual < 250°C, the lower limit P_engine_target_low'' of the current diesel engine target output power is compensated for power through the following formula: P_engine_target_low'' = P_engine_target_low' + ΔP_temp1, In the formula, ΔP_temp1 is the first temperature compensation power, which is calculated through the following formula: ΔP_temp1 = (250 - T_exh_actual) × 0.5kW / °C; If T_exh_actual > 400°C, the upper limit P_engine_target_high'' of the current diesel engine target output power is compensated for power through the following formula: P_engine_target_high'' = P_engine_target_high' - ΔP_temp2 and P_engine_target_high'' ≥ P_engine_eco lower limit, In the formula, ΔP_temp2 is the second temperature compensation power, which is calculated using the following formula: ΔP_temp2= (T_exh_actual - 400) × 0.3kW / ℃; If 250℃≤T_exh_actual≤400℃, maintain the current target power range without compensation.

[0017] Secondly, the present invention provides a diesel engine output power control system based on battery SOC, comprising: The parameter acquisition module is used to acquire various parameters of the hybrid vehicle; among which, the various parameters include power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust after-treatment parameters. The control analysis module is used to construct a three-level decision logic based on multiple parameters of the hybrid vehicle, and to obtain the current target output power range of the diesel engine through the three-level decision logic; The execution module is used to send the current target output power range of the diesel engine to the diesel engine controller via the hybrid vehicle controller. The diesel engine controller adjusts according to the current target output power range of the diesel engine to control the actual output power of the diesel engine within the current target output power range. The actual output power and current exhaust temperature of the diesel engine are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range of the diesel engine or the current exhaust temperature of the oil pump exceeds a specific range of the pre-acquired optimal after-treatment temperature range, the target output power range of the diesel engine is recalculated.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention introduces a diesel engine output power control method based on battery SOC. By dividing the current SOC value of the power battery into different intervals, and then solving for the upper and lower limits of the diesel engine's power in each interval, an initial range for the target output power of the diesel engine is obtained. This dynamic range power calculation method can rationally allocate the diesel engine's output power according to actual conditions, reducing fuel consumption. For example, when the current SOC is in the low SOC range, calculating the diesel engine's output power needs to prioritize charging the power battery to avoid battery depletion; when the current SOC is in the medium SOC range, calculating the diesel engine's output power needs to consider the balance between power supply, diesel exhaust aftertreatment temperature, and fuel consumption; when the current SOC is in the high SOC range, to satisfy the shallow charge and discharge characteristics of the power battery, the diesel engine's charging power needs to be limited.

[0019] This invention corrects the initial range (upper and lower limits) of the target output power of the diesel engine by relating the current requested power of the vehicle to the initial range (upper and lower limits) of the target output power of the diesel engine. It can determine, based on the actual situation, whether to prioritize meeting the vehicle's power demand or to actively increase the diesel engine power to maintain the after-treatment temperature. Furthermore, it compensates for the power range after correction by relating the current exhaust temperature of the oil pump to the optimal temperature range of the aftertreatment. This overcomes the contradiction in the prior art of sacrificing fuel consumption for temperature increase or abandoning emissions for fuel saving, as well as the problem of not being able to achieve multi-objective synergistic optimization. Attached Figure Description

[0020] Figure 1 The diagram shows a schematic flow chart of a diesel engine output power control method based on battery SOC according to the present invention. Detailed Implementation

[0021] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details. In this description, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0022] Example 1 This embodiment provides a diesel engine output power control method based on battery SOC, including the following: Acquire multiple parameters of the hybrid vehicle; wherein, the multiple parameters include power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust aftertreatment parameters; A three-level decision logic is constructed based on multiple parameters of the hybrid vehicle, and the target output power range of the current diesel engine is obtained through the three-level decision logic. The hybrid vehicle controller sends the current target output power range of the diesel engine to the diesel engine controller, so that the diesel engine controller can adjust the actual output power of the diesel engine according to the current target output power range, and control the actual output power of the diesel engine within the current target output power range. The actual output power of the diesel engine and the current exhaust temperature of the oil pump are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range or the current exhaust temperature of the diesel engine exceeds a specific range of the pre-acquired optimal aftertreatment temperature range, the target output power range of the diesel engine is recalculated.

[0023] Example 2 Based on Example 1, this example describes the specific implementation process of a diesel engine output power control method based on battery SOC, such as... Figure 1 As shown, it specifically includes the following: I. Real-time acquisition of multiple performance parameters of hybrid vehicles In one specific embodiment of the present invention, a paver is selected for the hybrid vehicle.

[0024] In one specific embodiment of the present invention, the power battery parameters are provided by the power battery management system (BMS), including the current SOC value SOC_current, the maximum allowable charging power P_charge_max and the maximum allowable discharging power P_discharge_max of the power battery at the current cell temperature; External operating condition load parameters include the hybrid vehicle's current requested power P_load, which is calculated collaboratively from the energy consumption parameters of each subsystem of the paver. The calculation formula is as follows: P_load = Power of material conveying system + Power of material distribution system + Power of hydraulic pump station system + Power of ironing plate heating system + Power of low-voltage battery charging system; The diesel engine parameters are provided by the diesel engine controller (ECU), including the current output power P_engine_actual and the optimal fuel economy power range P_engine_eco. The optimal fuel economy power range P_engine_eco is calibrated through bench testing, and its empirical value is above 60% of the diesel engine's rated power. The exhaust gas aftertreatment parameters are provided by the exhaust temperature sensor, including the minimum sustained aftertreatment temperature power of the diesel engine P_engine_min_temp and the current exhaust temperature of the oil pumping unit T_exh_actual. The minimum sustained aftertreatment temperature power of the diesel engine P_engine_min_temp is calibrated through bench testing to ensure that the exhaust temperature of the diesel engine is ≥250℃.

[0025] II. Construct a three - level decision logic to obtain the current target output power range of the diesel engine Step 2.1, construct the first - level SOC state classification decision In a specific implementation manner of the embodiment of the present invention, construct the first - level SOC state classification decision according to the power battery parameters. The first - level SOC state classification decision includes dividing the current SOC value SOC_current into a low SOC range, a medium SOC range, and a high SOC range according to the range where the current SOC value SOC_current is located. According to the first - level SOC state classification decision, delineate the first range of the diesel engine target output power, and then calculate the upper and lower limits of the power of each range respectively. The specific contents are as follows: Step 2.1.1, low SOC range In a specific implementation manner of the embodiment of the present invention, when SOC_current≤20%, the current SOC value SOC_current belongs to the low SOC range, and priority is given to ensuring the charging of the power battery to avoid battery discharge.

[0026] In the low SOC range, the lower limit of the diesel engine target output power P_engine_target_low1 is obtained by calculating with the following formula: P_engine_target_low1 = P_load + P_charge_req, In the formula, P_charge_req is the power demand for charging the power battery, and is obtained by calculating with the following formula: P_charge_req = k×(SOC_target - SOC_current), In the formula, k is the charging power coefficient, which is corrected according to the temperature of the power battery, SOC_target is the target SOC value, which is set to 80% in this embodiment, and P_engine_target_low1≥P_engine_min_temp; The upper limit of the diesel engine target output power P_engine_target_high1 = the upper limit of P_engine_eco. Avoid excessive power causing increased fuel consumption Step 2.1.2, medium SOC range In a specific implementation manner of the embodiment of the present invention, when 20% < SOC_current < 80%, the current SOC value SOC_current belongs to the medium SOC range, and the main task in this state is to balance power supply, after - treatment temperature, and fuel consumption.

[0027] In the medium SOC range, the lower limit of the diesel engine target output power P_engine_target_low2 is obtained by calculating with the following formula: P_engine_target_low2=P_engine_min_temp, The upper limit of the target output power of the diesel engine, P_engine_target_high2, is calculated using the following formula: P_engine_target_high2 = upper limit of P_engine_eco, and P_engine_target_high2 ≤ P_load + P_charge_max. This avoids overcharging.

[0028] Step 2.1.3, High SOC Range In one specific embodiment of the present invention, when SOC_current≥80%, the current SOC value SOC_current belongs to the high SOC range. At this time, the shallow charge and discharge characteristics of the power battery are satisfied, and the charging power of the diesel engine needs to be limited.

[0029] In the high SOC range, the lower limit of the target output power of the diesel engine, P_engine_target_low3, is calculated using the following formula: P_engine_target_low3= P_engine_min_temp, The upper limit of the target output power of the diesel engine, P_engine_target_high3, is calculated using the following formula: P_engine_target_high3 = P_load + P_charge_limit, In the formula, P_charge_limit represents the maximum allowable charging power of the power battery in the high SOC range. In this invention, P_charge_limit is set to 20% of P_charge_max to prevent overcharging of the power battery.

[0030] Step 2.2: Construct the second-level dynamic adjustment hierarchical decision-making system for operating conditions and loads. In one specific embodiment of the present invention, a second-level dynamic correction and hierarchical decision for operating condition load is constructed based on external operating condition load parameters. This second-level dynamic correction and hierarchical decision includes the relationship between the vehicle's current requested power P_load and the boundaries (upper and lower limits) of the first interval of the diesel engine's target output power. The first interval of the diesel engine's target output power is corrected based on the second-level dynamic correction and hierarchical decision to obtain the second interval of the diesel engine's target output power. Specifically, this includes the following: When P_load > P_engine_target_high_i, where i ranges from 1 to 3, representing the upper limits of the diesel engine target output power in the low SOC range, medium SOC range, and high SOC range respectively, and giving priority to meeting the vehicle power demand, the upper limit P_engine_target_high' of the second interval of the diesel engine target output power is obtained by correcting through the following formula: P_engine_target_high' = P_load + P_charge_max Or P_engine_target_high' = P_load + P_charge_limit, and P_engine_target_high' ≤ the rated power of the diesel engine; (to avoid over-power operation).

[0031] When P_load < P_engine_target_low_i, where i ranges from 1 to 3, representing the lower limits of the diesel engine target output power in the low SOC range, medium SOC range, and high SOC range respectively, actively increase the diesel engine power to maintain the aftertreatment temperature, and the lower limit of the second interval of the diesel engine target output power is obtained by correcting through the following formula: P_engine_target_low' = P_engine_min_temp.

[0032] The power of the diesel engine exceeding P_load is used for charging the power battery (that is, P_engine_target_low' - P_load ≤ P_charge_max, if it exceeds, appropriately reduce P_engine_target_low' to ensure that it does not exceed the charging power limit). Step 2.3, construct the third-level aftertreatment temperature-power feedback compensation hierarchical decision In a specific implementation manner of the embodiment of the present invention, construct the third-level aftertreatment temperature-power feedback compensation hierarchical decision according to the exhaust aftertreatment parameters. Among them, the third-level aftertreatment temperature-power feedback compensation hierarchical decision includes the relationship between the current exhaust temperature T_exh_actual of the oil engine and the optimal aftertreatment temperature range, and the optimal aftertreatment temperature range is 250°C - 400°C. Perform power compensation on the second interval of the diesel engine target output power according to the third-level aftertreatment temperature-power feedback compensation hierarchical decision to obtain the current diesel engine target output power interval. The specific content is as follows: The current diesel engine target output power interval includes: If T_exh_actual < 250°C, the lower limit P_engine_target_low'' of the current diesel engine target output power is power-compensated through the following formula: P_engine_target_low'' = P_engine_target_low' + ΔP_temp1, In the formula, ΔP_temp1 is the first temperature compensation power, which is calculated using the following formula: ΔP_temp1 = (250 - T_exh_actual) × 0.5kW / ℃; If T_exh_actual > 400℃, to avoid overheating and damage to the diesel engine exhaust aftertreatment system, the current target output power limit P_engine_target_high of the diesel engine is compensated using the following formula: P_engine_target_high'' = P_engine_target_high' - ΔP_temp2 and P_engine_target_high'' ≥ P_engine_eco lower limit (to ensure fuel economy). In the formula, ΔP_temp2 is the second temperature compensation power, which is calculated using the following formula: ΔP_temp2= (T_exh_actual - 400) × 0.3kW / ℃; If 250℃≤T_exh_actual≤400℃, maintain the current target power range without compensation.

[0033] Step 2 yields the final range of the current target output power of the diesel engine (P_engine_target_low'', P_engine_target_high'').

[0034] III. Closed-loop feedback control to stabilize diesel engine output power Step 3.1: Send the current target output power range of the diesel engine obtained in Step 2 to the diesel engine controller through the hybrid vehicle controller; Step 3.2: The diesel engine controller adjusts according to the current target output power range of the diesel engine to control the actual output power P_engine_actual of the diesel engine within the current target output power range. Step 3.3: The hybrid vehicle controller collects the actual output power P_engine_actual and the current exhaust temperature T_exh_actual of the diesel engine every 100ms. If the actual output power P_engine_actual of the diesel engine exceeds ±5% of the current target output power range of the diesel engine, or if the current exhaust temperature T_exh_actual of the oil pump exceeds ±20℃ of the optimal after-treatment temperature range of 250℃-400℃, then repeat step 2 to recalculate the target output power range of the diesel engine.

[0035] IV. Examples 4.1 Paver relocation (low load, medium SOC zone) In one specific embodiment of the present invention, a scenario of a paver relocation is selected under low load and medium SOC range, illustrated with specific data: Operating parameters: Power battery parameters: SOC_current=50%, P_charge_max=30kW, P_discharge_max=50kW; External load parameters: Paver transfer, moving forward unloaded, calculated P_load=15kW; Diesel engine bench parameters: P_engine_eco = 40kW-60kW (diesel engine rated power 100kW). Exhaust gas aftertreatment parameters: P_engine_min_temp=35kW (ensuring T_exh_actual≥250℃), current T_exh_actual=230℃ (below the lower limit of T_exh_opt). T_exh_opt is the optimal temperature range for aftertreatment, 250℃-400℃.

[0036] The control process for the diesel engine's output power is as follows: Step S1: The hybrid vehicle controller (VCU) collects the above parameters and determines that T_exh_actual = 230℃, and needs to compensate ΔP_temp1 (for every 10℃ decrease, the rated power increases by 5%, i.e., 5kW, so ΔP_temp1 = 10kW). Step S2: Based on the three-level decision logic, obtain the current target output power range of the diesel engine. Step S2.1, solve for the lower limit of the current target output power of the diesel engine according to the first level SOC state classification decision: Since SOC_current=50%, according to the formula P_engine_target_low2=P_engine_min_temp in step 2.1.2, the initial target power lower limit is P_engine_min_temp1=P_engine_min_temp=35kW; Step S2.2: Adjust the target power lower limit obtained in step S2.1 according to the dynamic correction classification decision of the second-level working condition load: Since P_load=15kW<35kW, according to the formula P_engine_target_low' = P_engine_min_temp in step 2.2, the target power lower limit P_engine_min_temp2=P_engine_min_temp=35kW needs to be adjusted. The excess part (20kW) is used for power battery charging, and 20kW ≤ P_charge_max=30kW, which meets the requirements. Step S2.3: Based on the third-level post-processing temperature power feedback compensation hierarchical decision, perform power compensation on the target power lower limit obtained in step S2.2: Since T_exh_actual = 230℃ is 20℃ lower than 250℃, ΔP_temp1 = 10kW. According to the formula P_engine_target_low'' = P_engine_target_low' + ΔP_temp1 in step 2.3, the target power lower limit P_engine_min_temp2 needs to be fed back and compensated to 35 + 10 = 45kW.

[0037] In summary, the target output power range for the diesel engine is 45kW-60kW (60kW is the upper limit of P_engine_eco).

[0038] In step S3, the target output power range of 45kW-60kW for the diesel engine is sent to the diesel engine controller ECU via the hybrid vehicle controller VCU. The ECU controls the fuel injection quantity of the diesel engine to stabilize the actual power at 50kW (within the optimal economic range). At this time, the exhaust temperature of the diesel engine gradually rises to 280℃ (entering the T_exh_opt range). The 35kW exceeding P_load (15kW) is used to charge the power battery (since 35kW≤30kW, this is corrected here: the actual charging power is 50-15=35kW, which exceeds P_charge_max=30kW, so the VCU adjusts the target power to 45kW, and the charging power is 45-15=30kW, which meets the limit). Finally, the diesel engine power stabilizes at 45kW, T_exh_actual is maintained at 260℃, and the fuel consumption rate is in the optimal range. The aforementioned 280℃ is based on data from actual operation. This is because the exhaust gas will heat up after passing through the first DOC of the engine exhaust aftertreatment system. The temperature at which the first DOC starts working is 250 degrees Celsius. Once the first DOC enters working mode, the temperature of the exhaust gas will gradually increase.

[0039] 4.2 Medium-width paving operation conditions (medium load, high SOC zone) In one specific embodiment of the present invention, a scenario of medium-width paving operation is selected, and specific data is used to illustrate the following: Operating parameters: Power battery parameters: SOC_current=85%, P_charge_max=30kW, P_charge_limit=6kW; External load parameters: For paving a thin layer of asphalt, the speed is slow and the load is low. The calculated load is P_load=50kW. Diesel engine parameters: P_engine_eco=40-60kW Exhaust gas aftertreatment parameters: P_engine_min_temp=35kW, current T_exh_actual=320℃ (within the T_exh_opt range). The control process for the diesel engine's output power is as follows: Step S1: The hybrid vehicle controller (VCU) collects the above parameters and determines that the current SOC value belongs to the high SOC range and that T_exh_actual is normal; Step S2: Step 2.1, solve for the upper limit of the current target output power of the diesel engine according to the first level SOC state classification decision: Since SOC_current=85%, it belongs to the high SOC range. According to the formula P_engine_target_high3 = P_load + P_charge_limit in step 2.1.3 above, the target power upper limit is P_load + P_charge_limit=50+6=56kW, and the lower limit is P_engine_min_temp=35kW. Step 2.2: Correct the target power obtained in step S2.1 according to the dynamic correction classification decision of the second-level working condition load. Since P_load=50kW is in the range of 35-56kW and 50kW is in the range of P_engine_eco (40-60kW), no correction is required. Step 2.3: Perform power compensation on the target power lower limit obtained in step S2.2 according to the third-level post-processing temperature power feedback compensation hierarchical decision: Since T_exh_actual is normal and within the T_exh_opt range of 250℃-400℃, no compensation is required; In summary, the target output power range for the diesel engine is 50kW-56kW. In step S3, the ECU controls the diesel engine power to stabilize at 52kW, of which 50kW meets the load requirements and 2kW is used for charging the power battery (≤6kW). T_exh_actual is maintained at 320℃ to minimize fuel consumption and avoid overcharging of the power battery. Example

[0040] This embodiment provides a diesel engine output power control system based on battery SOC, including: The parameter acquisition module is used to acquire various parameters of the hybrid vehicle, including power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust aftertreatment parameters. The control analysis module is used to construct a three-level decision logic based on multiple parameters of the hybrid vehicle, and obtain the current target output power range of the diesel engine through the three-level decision logic; The execution module is used to send the current target output power range of the diesel engine to the diesel engine controller via the hybrid vehicle controller. The diesel engine controller adjusts according to the current target output power range to control the actual output power of the diesel engine within the current target output power range. The actual output power of the diesel engine and the current exhaust temperature of the oil pump are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range or the current exhaust temperature of the oil pump exceeds a specific range of the pre-acquired optimal after-treatment temperature range, the target output power range of the diesel engine is recalculated.

[0041] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for controlling the output power of a diesel engine based on battery SOC, characterized in that, include: Acquire multiple parameters of the hybrid vehicle; wherein, the multiple parameters include power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust aftertreatment parameters; A three-level decision logic is constructed based on multiple parameters of the hybrid vehicle, and the target output power range of the current diesel engine is obtained through the three-level decision logic. The hybrid vehicle controller sends the current target output power range of the diesel engine to the diesel engine controller, so that the diesel engine controller can adjust the actual output power of the diesel engine according to the current target output power range, and control the actual output power of the diesel engine within the current target output power range. The actual output power and current exhaust temperature of the diesel engine are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range or the current exhaust temperature of the oil pump exceeds a specific range of the pre-acquired optimal after-treatment temperature range, the target output power range of the diesel engine is recalculated.

2. The diesel engine output power control method based on battery SOC according to claim 1, characterized in that, The power battery parameters include the current SOC value SOC_current, the maximum allowable charging power P_charge_max and the maximum allowable discharging power P_discharge_max of the power battery at the current cell temperature; The external operating condition load parameters include the hybrid vehicle's current requested power P_load; The diesel engine parameters include the current output power of the diesel engine P_engine_actual and the optimal fuel economy power range of the diesel engine P_engine_eco. The exhaust gas aftertreatment parameters include the minimum sustained aftertreatment temperature power of the diesel engine P_engine_min_temp and the current exhaust temperature of the oil pumping unit T_exh_actual.

3. The diesel engine output power control method based on battery SOC according to claim 2, characterized in that, The three-level decision-making logic includes constructing a first-level SOC state classification decision based on the power battery parameters, constructing a second-level dynamic correction classification decision based on the external operating load parameters, and constructing a third-level after-treatment temperature and power feedback compensation classification decision based on the exhaust after-treatment parameters. The first-level SOC state classification decision includes dividing the current SOC value into a low SOC range, a medium SOC range, and a high SOC range based on the range of the current SOC value; the second-level operating condition load dynamic correction classification decision includes the relationship between the vehicle's current requested power and the first range boundary of the diesel engine's target output power; the third-level after-treatment temperature power feedback compensation classification decision includes the relationship between the oil pumping unit's current exhaust temperature and the optimal after-treatment temperature range, where the optimal after-treatment temperature range is 250℃-400℃.

4. The diesel engine output power control method based on battery SOC according to claim 3, characterized in that, The three-level decision logic is used to obtain the current target output power range of the diesel engine, including defining the first range of the target output power of the diesel engine according to the first-level SOC state hierarchical decision. The first range of the target output power of the diesel engine is modified according to the dynamic correction and hierarchical decision of the second-level operating condition load to obtain the second range of the target output power of the diesel engine. Perform power compensation on the second interval of the diesel engine target output power according to the above-mentioned third-stage post-processing temperature power feedback compensation grading decision to obtain the current diesel engine target output power interval.

5. The diesel engine output power control method based on battery SOC according to claim 4, characterized in that, When SOC_current ≤ 20%, SOC_current belongs to the low SOC interval. In this low SOC interval, the lower limit of the diesel engine target output power P_engine_target_low1 is calculated by the following formula: P_engine_target_low1 = P_load + P_charge_req, where P_charge_req is the power required for charging the power battery and is calculated by the following formula: P_charge_req = k × (SOC_target - SOC_current), where k is the charging power coefficient, corrected according to the temperature of the power battery cell, SOC_target is the target SOC value, and P_engine_target_low1 ≥ P_engine_min_temp; The upper limit of the diesel engine target output power P_engine_target_high1 = the upper limit of P_engine_eco.

6. The diesel engine output power control method based on battery SOC according to claim 5, characterized in that, When 20% < SOC_current < 80%, SOC_current belongs to the medium SOC interval. In this medium SOC interval, the lower limit of the diesel engine target output power P_engine_target_low2 is calculated by the following formula: P_engine_target_low2 = P_engine_min_temp, The upper limit of the diesel engine target output power P_engine_target_high2 is calculated by the following formula: P_engine_target_high2 = the upper limit of P_engine_eco, and P_engine_target_high2 ≤ P_load + P_charge_max.

7. The diesel engine output power control method based on battery SOC according to claim 6, characterized in that, When SOC_current ≥ 80%, SOC_current belongs to the high SOC interval. In this high SOC interval, the lower limit of the diesel engine target output power P_engine_target_low3 is calculated by the following formula: P_engine_target_low3 = P_engine_min_temp, The upper limit of the diesel engine target output power P_engine_target_high3 is calculated by the following formula: P_engine_target_high3 = P_load + P_charge_limit, where P_charge_limit is the maximum allowable charging power of the power battery in the high SOC interval.

8. The diesel engine output power control method based on battery SOC according to claim 7, characterized in that, The second interval of the diesel engine target output power includes: When P_load > P_engine_target_high_i, the value of i ranges from 1 to 3, representing the upper limit of the target output power of the diesel engine in the low SOC, medium SOC, and high SOC ranges, respectively. The upper limit of the target output power of the diesel engine in the second range, P_engine_target_high', is obtained by correcting it using the following formula: P_engine_target_high' = P_load + P_charge_max Or P_engine_target_high' = P_load + P_charge_limit, and P_engine_target_high' ≤ diesel engine rated power; When P_load < P_engine_target_low_i, the value of i ranges from 1 to 3, representing the lower limit of the target output power of the diesel engine in the low SOC, medium SOC, and high SOC ranges, respectively. The lower limit of the target output power of the diesel engine in the second range is obtained by correcting it using the following formula: P_engine_target_low' = P_engine_min_temp.

9. The diesel engine output power control method based on battery SOC according to claim 8, characterized in that, The current target output power range for diesel engines includes: If T_exh_actual < 250℃, the current target output power lower limit P_engine_target_low of the diesel engine is compensated for using the following formula: P_engine_target_low'' = P_engine_target_low' + ΔP_temp1, In the formula, ΔP_temp1 is the first temperature compensation power, which is calculated using the following formula: ΔP_temp1 = (250 - T_exh_actual) × 0.5kW / ℃; If T_exh_actual > 400℃, the current target output power limit of the diesel engine, P_engine_target_high, is compensated for using the following formula: P_engine_target_high'' = P_engine_target_high' - ΔP_temp2 and P_engine_target_high'' ≥ P_engine_eco lower limit, In the formula, ΔP_temp2 is the second temperature compensation power, which is calculated using the following formula: ΔP_temp2= (T_exh_actual - 400) × 0.3kW / ℃; If 250℃≤T_exh_actual≤400℃, maintain the current target power range without compensation.

10. A diesel engine output power control system based on battery SOC, characterized in that, include: The parameter acquisition module is used to acquire various parameters of the hybrid vehicle; among which, the various parameters include power battery parameters, external operating condition load parameters, diesel engine parameters, and exhaust after-treatment parameters. The control analysis module is used to construct a three-level decision logic based on multiple parameters of the hybrid vehicle, and to obtain the current target output power range of the diesel engine through the three-level decision logic; The execution module is used to send the current target output power range of the diesel engine to the diesel engine controller via the hybrid vehicle controller, so that the diesel engine controller adjusts the actual output power of the diesel engine according to the current target output power range, and controls the actual output power of the diesel engine within the current target output power range. The actual output power and the current exhaust temperature of the diesel engine are collected at specific intervals. If the actual output power of the diesel engine exceeds a specific range of the current target output power range or the current exhaust temperature of the oil pump exceeds a specific range of the pre-acquired optimal aftertreatment temperature range, the target output power range of the diesel engine is recalculated.

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