Series-parallel non-plug-in hybrid electric balance control method and system based on WLTC working condition

Abstract

The invention discloses a series-parallel non-plug-in hybrid electric balance control method and system based on a WLTC working condition, and belongs to the field of hybrid electric vehicle control electric balance, and the method comprises the steps: dividing the state of charge of a battery into a normal SOC level interval and a high SOC level interval, entering a high SOC level critical line from a normal SOC level, and presenting a concave characteristic in an ultra-high speed interval of the WLTC working condition; engine torque and motor torque are distributed according to the SOC level, the vehicle speed signal, the accelerator signal, the brake signal and the gear signal; at the normal SOC level, the torque distributed to the engine is larger than the original required torque of the engine; when the SOC level is high, the vehicle speed is lower than a preset high vehicle speed threshold value, the torque distributed to the engine is smaller than the original required torque, and the vehicle speed is not lower than the preset high vehicle speed threshold value, the engine is directly driven; the preset high vehicle speed threshold value falls into an ultra-high speed interval. According to the method, the electric balance requirement can be met through a single test of a WLTC test cycle, repeated tests are avoided, test resources and cost are saved, and the method is not influenced by operation of a driver and has high robustness.

Description

Technical Field

[0001] This application relates to the field of electric balance control for hybrid electric vehicles, specifically to a series-parallel non-plug-in hybrid electric balance control method and system based on the WLTC (Worldwide Harmonized Light Vehicles Test Cycle) operating condition. Background Technology

[0002] With increasingly stringent global requirements for vehicle emissions and fuel economy, non-plug-in hybrid electric vehicles (HEVs, Hybrid Electric Vehicles) have been widely adopted as an important energy-saving and emission-reduction technology. In the development of hybrid vehicles, electric balance control under the WLTC (Wait-Trip Cycle) test is one of the core technical indicators for meeting national emission and fuel consumption standards. Electric balance requirements refer to controlling the change in the battery pack's SOC (State of Charge) within a specific range during the WLTC test cycle.

[0003] Currently, the commonly used electrical balance control methods in existing technologies mainly rely on self-learning mechanisms, such as the technical solution disclosed in Chinese patent CN118372719A. This solution dynamically adjusts control parameters based on historical test data through multiple WLTC test cycles to achieve the electrical balance target. However, this technical solution has the following obvious drawbacks: Achieving electrical balance in a single test cannot be guaranteed: Because the self-learning mechanism relies on the accumulation of data from multiple tests, it cannot ensure that the SOC change meets the requirements in a single WLTC test cycle. In actual testing, 2-3 or even more repeated tests are usually required to achieve the electrical balance standard.

[0004] The waste of testing resources is serious: a single WLTC test cycle usually takes an hour, and a single vehicle can only be tested once a day. Repeated testing not only leads to long-term occupation of test bench resources, but also increases the testing manpower and time costs, which has a significant impact on the vehicle development cycle.

[0005] Poor robustness: Existing technology is sensitive to driver operation, and different drivers' driving habits can cause large fluctuations in the SOC change trend, making it impossible to guarantee the stability and consistency of test results.

[0006] Lack of targeted control strategies: Existing technologies have not designed refined control strategies for the specific characteristics of WLTC operating conditions, making it difficult to achieve precise electric balance control in key operating conditions such as ultra-high speed range (above 100km / h), and making it impossible to achieve optimal energy distribution in special operating conditions such as ultra-high speed range.

[0007] Therefore, existing technologies have significant shortcomings in achieving electrical balance control under WLTC conditions, failing to meet the urgent needs for testing efficiency, control accuracy, and resource conservation in hybrid vehicle development. There is a pressing need for a control method and system that can ensure electrical balance requirements are met in a single WLTC test cycle, thereby improving testing efficiency, reducing development costs, and guaranteeing the robustness and adaptability of the control strategy. Summary of the Invention

[0008] This application provides a series-parallel non-plug-in hybrid electric balance control method and system based on WLTC operating conditions, which can solve the technical problem in the prior art that the electric balance requirements cannot be achieved in a single WLTC cycle test, resulting in long test cycles and serious waste of resources.

[0009] In a first aspect, embodiments of this application provide a series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions, the method comprising: Real-time collection of battery state of charge, vehicle speed signal, throttle signal, braking signal and gear signal; The engine is started or stopped based on the battery state of charge, vehicle speed signal, throttle signal and gear signal; The battery state of charge is divided into a normal SOC level range and a high SOC level range. The SOC level division is related to vehicle speed and has hysteresis characteristics. The critical line from the normal SOC level to the high SOC level shows a concave feature in the ultra-high speed range of WLTC conditions. Engine torque and electric motor torque are distributed according to SOC level, vehicle speed signal, throttle signal, braking signal and gear signal; At a normal SOC level, the torque allocated to the engine is greater than its original required torque; at a high SOC level, when the vehicle speed is lower than a preset high vehicle speed threshold, the torque allocated to the engine is less than its original required torque, and when the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly; the preset high vehicle speed threshold falls into the ultra-high speed range.

[0010] In conjunction with the first aspect, in one implementation, the engine start-up threshold and stop-up threshold are determined by a two-dimensional mapping relationship between vehicle speed and throttle signal.

[0011] In conjunction with the first aspect, in one embodiment, the division of the SOC level range includes: when the battery state of charge rises to a high SOC threshold, switching the SOC level to a high SOC level; when the battery state of charge drops to a low SOC threshold, switching the SOC level back to a normal SOC level.

[0012] In conjunction with the first aspect, in one implementation, the critical line from the normal SOC level to the high SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0013] In conjunction with the first aspect, in one implementation, the threshold for transitioning from a high SOC level to a normal SOC level is a horizontal line throughout the WLTC operating conditions.

[0014] In conjunction with the first aspect, in one implementation, the critical line for transitioning from a high SOC level to a normal SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0015] In conjunction with the first aspect, in one implementation, the threshold between high SOC level and normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

[0016] In conjunction with the first aspect, in one implementation, the step of distributing engine torque and electric motor torque according to SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is below the preset high threshold, torque is allocated based on the universal characteristic map to allocate the engine with the optimal operating point torque that is greater than the original required torque.

[0017] In conjunction with the first aspect, in one implementation, the step of distributing engine torque and electric motor torque according to SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is not lower than the preset high threshold, torque is allocated based on the universal characteristic map to allocate the engine with the optimal operating point torque that is greater than the original required torque.

[0018] In conjunction with the first aspect, in one implementation, the step of distributing engine torque and electric motor torque according to SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the SOC level is high and the vehicle speed is lower than the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque, which is less than the original required torque.

[0019] In conjunction with the first aspect, in one embodiment, the concave feature refers to a concave step, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

[0020] Secondly, embodiments of this application provide a series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions, the system comprising: The input module is used to collect battery state of charge, vehicle speed signal, throttle signal, braking signal and gear signal in real time; The engine start-stop module includes a start control submodule and a stop control submodule, which control the engine to start or stop based on the battery charge status, vehicle speed signal, throttle signal and gear signal; The SOC classification module is used to divide the battery state of charge into a normal SOC level range and a high SOC level range. The SOC level classification is related to vehicle speed and has hysteresis characteristics. The critical line from the normal SOC level to the high SOC level shows a concave feature in the ultra-high speed range of WLTC conditions. The torque distribution module distributes engine torque and motor torque according to SOC level, vehicle speed signal, throttle signal, braking signal, and gear signal. At normal SOC level, the torque distributed to the engine is greater than its original required torque. At high SOC level, when the vehicle speed is lower than a preset high vehicle speed threshold, the torque distributed to the engine is less than its original required torque. When the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly. The preset high vehicle speed threshold falls within the ultra-high speed range. The execution module is used to control engine start / stop and torque distribution.

[0021] In conjunction with the second aspect, in one implementation, the threshold between high SOC level and normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

[0022] In conjunction with the second aspect, in one embodiment, the concave feature refers to a concave step, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

[0023] In conjunction with the second aspect, in one embodiment, the system further includes a braking energy recovery module for performing energy recovery during braking.

[0024] The beneficial effects of the technical solutions provided in this application include: By utilizing the concave design of the critical line between normal and high SOC levels in the ultra-high-speed range (e.g., the critical point drops from 65% to 59%), the system precisely controls the SOC to automatically switch to a high SOC level after charging in the ultra-high-speed range (e.g., the SOC value rises to 59%). Combined with the triggering of engine direct drive mode when the vehicle speed exceeds a preset high-speed threshold (e.g., ≥100km / h), the SOC remains stable during the direct drive phase (e.g., maintained at 59%, with no charging or discharging losses). During the braking phase in the ultra-high-speed range, energy recovery replenishes some SOC (approximately 6%), ultimately allowing the SOC to accurately return to its initial value (e.g., recovering 6% from 59% to return to the initial value of 65%, ΔSOC=0). This achieves, for the first time, meeting the electrical balance requirements (e.g., SOC start-stop difference ≤2.6%, |energy change| ≤1%) in a single WLTC cycle test, avoiding the resource waste of multiple tests required by traditional technologies and significantly reducing testing costs and cycles. Attached Figure Description

[0025] Figure 1 The speed curve for the WLTC cycle test; Figure 2 This is a schematic flowchart of an embodiment of the series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions in this application; Figure 3 This is a schematic diagram of the startup map in a specific embodiment of this application; Figure 4 This is a schematic diagram of a shutdown map in a specific embodiment of this application; Figure 5 This is a schematic diagram of SOC level division in a specific embodiment of this application; Figure 6 This is a schematic diagram of torque distribution at a normal SOC level engine in a specific embodiment of this application; Figure 7 This is a schematic diagram of torque distribution in a high SOC-level engine according to a specific embodiment of this application; Figure 8 This is a functional module diagram of an embodiment of the series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions in this application; Figure 9 This is a schematic diagram of the actual WLTC process in a specific embodiment. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0027] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0028] The speed curve of the WLTC cyclic test, refer to Figure 1 The WLTC cycle is divided into four phases: low speed, medium speed, high speed and ultra-high speed. The maximum speed in the low speed phase is 56.5 km / h, the maximum speed in the medium speed phase is 76.6 km / h, the maximum speed in the high speed phase is 97.4 km / h, and the maximum speed in the ultra-high speed phase is 131.3 km / h.

[0029] Emissions regulation 18352.6 specifies the criteria for judging the validity of WLTC testing: if the energy change ΔEreess of the WLTC driving cycle is negative, then the percentage of ΔEreess to the total energy of the driving cycle (Energytotal) must be less than or equal to 1%. Assuming the total energy of the cycle (Energytotal) is 4000 Wh (the total energy of the cycle can be calculated by integrating road resistance and loading inertia), the discharge energy ΔEreess cannot exceed 40 Wh (i.e., |ΔEreess / Energytotal| ≤ 1%). Assuming the battery pack capacity is approximately 1.5 kWh, this translates to a SOC decrease of no more than 2.6% (i.e., (|ΔEreess| / 1%)). (Total battery capacity ≤ 2.6%). To maintain fuel economy, overcharging should be avoided as it would increase fuel consumption. Therefore, a control system is needed to ensure that power generation and power consumption are approximately equal. The simplest and most effective method is to ensure that the initial and final SOCs of the test are approximately equal. If they are not equal, the difference should be kept between -2.6% and 2.6%.

[0030] The original torque demand of the parallel engine, or simply the original torque demand of the engine, refers to the original value of the vehicle's original torque demand (the greater the throttle, the greater the original torque demand) allocated to the engine in parallel operation. The original torque demand of the parallel engine = wheel-end torque demand / engine speed ratio + near-terminal power demand * 9550 / engine speed. The electric balance strategy of this invention primarily controls parallel operation at speeds above 45 km / h; therefore, this invention only describes the torque distribution strategy for parallel operation.

[0031] The optimal operating point is the torque corresponding to the most economical point in the engine's universal characteristic map, denoted as Tq_opt. Taking a certain 1.5DHE engine as an example, the torque corresponding to the most economical point in the engine's universal characteristic map is 130Nm, so Tq_opt=130Nm.

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0033] In a first aspect, embodiments of this application provide a series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions.

[0034] In one embodiment, reference is made to Figure 2 , Figure 2 This is a schematic flowchart of an embodiment of the series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions according to this application. Figure 2 As shown, the series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions includes: Step S1: Collect battery charge status, vehicle speed signal, throttle signal, braking signal and gear signal in real time.

[0035] Step S2: Control the engine to start or stop based on the battery state of charge, vehicle speed signal, throttle signal, and gear signal. The higher the vehicle speed and throttle, the higher the start point (the higher the start map value), and the higher the corresponding stop point (the higher the stop map value). The engine is set to not stop when the vehicle speed exceeds the ultra-high speed threshold (e.g., 100km / h).

[0036] Step S3: Divide the battery state of charge into a normal SOC level range and a high SOC level range. The SOC level division is related to vehicle speed and has hysteresis characteristics. The critical line from the normal SOC level to the high SOC level shows a concave characteristic in the ultra-high speed range of WLTC conditions.

[0037] Step S4: Distribute engine torque and motor torque according to SOC level, vehicle speed signal, throttle signal, brake signal and gear signal.

[0038] At the normal SOC level, the torque allocated to the engine is greater than its original required torque. At the high SOC level, when the vehicle speed is below the preset high vehicle speed threshold, the torque allocated to the engine is less than its original required torque; when the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly. The preset high vehicle speed threshold falls into the ultra-high speed range.

[0039] In this embodiment, the design of a concave transition line from normal SOC level to high SOC level in the ultra-high speed range (e.g., the critical point drops from 65% to 59%) is utilized to precisely control the SOC to automatically switch to a high SOC level after charging in the ultra-high speed range (e.g., the SOC value rises to 59%). Combined with the engine direct drive mode being triggered when the vehicle speed exceeds 100km / h without stopping and the vehicle speed exceeds a preset high vehicle speed threshold (e.g., ≥100km / h), the SOC is kept stable during the direct drive phase (e.g., maintained at 59%, without charging or discharging damage).

[0040] During the ultra-high-speed interval braking phase, energy recovery replenishes part of the SOC (approximately 6%), ultimately allowing the SOC to accurately return to its initial value (e.g., recovering 6% from 59% to return to the initial value of 65%, ΔSOC=0). For the first time, the WLTC cycle test can meet the electrical balance requirements in a single test (e.g., SOC start-stop difference ≤2.6%, |energy change| ≤1%), avoiding the resource waste of multiple tests required by traditional technologies and significantly reducing testing costs and cycles.

[0041] In one specific embodiment, the battery state of charge (SOC), vehicle speed signal, throttle signal, braking signal, and gear signal are collected in real time. The SOC is expressed as a percentage (e.g., 65%), the vehicle speed signal is in km / h, the throttle signal is expressed as a percentage (e.g., 30%), the braking signal is expressed as an intensity percentage (e.g., 50%), and the gear signal is expressed as the current gear (e.g., D or N).

[0042] The engine start-up and stop-up thresholds are determined by a two-dimensional mapping relationship between vehicle speed and throttle signal. The start-up threshold mapping range is 43%~65%, and the stop-up threshold mapping range is 46%~85%. For example, when the vehicle speed is 40km / h and the throttle signal is 30%, the start-up threshold is determined to be 48% and the stop-up threshold is 58% by referring to the table.

[0043] Startup map such as Figure 3 As shown, the engine start map is a two-dimensional map value. The horizontal axis represents vehicle speed, and the vertical axis represents throttle. The higher the vehicle speed and the higher the throttle, the larger the engine start map value. Its minimum value is 43, and its maximum value is 65, with the unit being %. For example, assuming the current SOC is 46%, the vehicle speed is 40 km / h, and the throttle is 30%, the engine start map value can be found to be 48% by looking up the table. Since the current SOC (46%) < engine start map (48%), an engine start request will be made.

[0044] shutdown map such as Figure 4As shown, the engine shutdown map is also a two-dimensional map value. The horizontal axis represents vehicle speed, and the vertical axis represents throttle. The higher the vehicle speed and the higher the throttle, the larger the engine shutdown map value. Its minimum value is 46, and its maximum value is 85. For example, assuming the current SOC is 55%, the vehicle speed is 50 km / h, and the throttle is 10%, the engine start map value can be found to be 54% by looking up the table. Since the current SOC (55%) > the engine shutdown map (54%), an engine shutdown request will be made. In addition, through fine design, it is possible to achieve engine shutdown even when the vehicle speed exceeds the ultra-high speed threshold (e.g., 100 km / h).

[0045] The battery state of charge (SOC) is divided into a normal SOC range and a high SOC range. During low-to-medium speed and ultra-high speed ranges, when the battery SOC rises to the high SOC threshold of 65%, the SOC level is switched to the high SOC level; when the battery SOC drops to the low SOC threshold of 55%, the SOC level is switched back to the normal SOC level. The SOC level range exhibits a concave characteristic within the ultra-high speed range of the WLTC cycle (e.g., 102 km / h to 138 km / h), meaning that within this speed range, the critical value for switching SOC levels is lower than in the normal range. For example, at a speed of 120 km / h, the critical value for transitioning from the normal SOC level to the high SOC level drops from 65% to 59%, and the critical value for transitioning from the high SOC level to the normal SOC level drops from 55% to 52%.

[0046] SOC level classification diagram as follows: Figure 5 As shown, the horizontal axis represents vehicle speed, and the vertical axis represents the State of Charge (SOC) value. The blue line is the critical line for transitioning from the normal SOC level to the high SOC level, and the yellow line is the critical line for transitioning from the high SOC level to the normal SOC level. The area above the blue line is the high SOC range, and the area between the blue and yellow lines is the hysteresis range.

[0047] To better understand the SOC range division, let's illustrate with an example. When the battery is charged, the SOC level is assumed to be the normal SOC level. Then, the SOC level range is calculated based on the SOC value. For example, if the vehicle speed is 145 km / h at a constant speed and the SOC is 46%, then the SOC level at that moment is the normal SOC level. If the battery pack is being charged at this time, the SOC will continue to rise. When the SOC reaches 62%, it is still at the normal SOC level. If it continues to rise to 69%, then the SOC level is the high SOC level. If the SOC then drops back to 60%, due to the existence of a hysteresis range, it is still at the high SOC level. Only when it drops below 55% will it return to the normal SOC range. The same applies to other vehicle speeds. Figure 5 The vehicle speed at both ends of the recessed step can be adjusted as needed, that is, it can be from 102km / h to 138km / h, or other speed ranges, and can be adjusted appropriately according to the requirements of WLTC. The critical value at the lowest point of the recessed step can also be adjusted.

[0048] Let Tq_opt be the torque corresponding to the most economical point in the engine's universal characteristic map. Taking a 1.5DHE engine as an example, the torque corresponding to the most economical point in the engine's universal characteristic map is 130 Nm, then Tq_opt = 130 Nm. The following discussion covers the allocation of engine torque in different cases: Reference Figure 6 When the State of Charge (SOC) is at a normal SOC level and the engine is running, below 100 km / h, the engine is operated as close to its optimal operating point as possible according to the engine's universal characteristic map. This means the torque allocated to the engine is around Tq_opt. When the initial torque requirement is below 130 Nm, the torque allocated to the engine is greater than its initial torque requirement (charging). When the initial torque requirement is above 130 Nm (requiring significant throttle), the torque allocated to the engine is less than its initial torque requirement (discharging). In WLTC conditions below 100 km / h, there is certainly no significant throttle input, so the initial torque requirement is generally less than 130 Nm, and the battery pack is generally charging.

[0049] The drive motor outputs positive torque (to drive the wheels) or negative torque (to charge the battery pack) based on the difference between the original required torque of the parallel engine and the engine torque. The drive motor torque = (original required torque of the parallel engine - engine torque) x engine speed ratio / drive motor speed ratio.

[0050] At speeds above 100 km / h, regardless of whether the original torque demand of the parallel engine is greater than or less than the optimal torque Tq_opt, the torque allocated to the engine will refer to the universal characteristic map, but will be appropriately greater than the original torque demand of the parallel engine. At this time, the battery pack will inevitably be charged, unless the original torque demand of the parallel engine is particularly high, but this exceeds the operating conditions of WLTC.

[0051] Reference Figure 7 When the SOC is at a high SOC level, above 100km / h, the engine is controlled to drive directly. At this time, the torque allocated to the engine is always equal to the original torque required by the parallel engine. The battery pack neither discharges nor charges (the SOC value remains unchanged). When the State of Charge (SOC) is at a high SOC level, below 100 km / h, engine torque is allocated according to the engine's universal characteristic map. The allocated torque is near the optimal torque Tq_opt, allowing the engine to operate near its most economical point. When the original torque requirement is below 130 Nm, the allocated torque is greater than the original torque requirement, but this will cause the engine to shut down, and the SOC will decrease. In other words, this torque allocation is not used, and there is no charging. When the original torque requirement is above 130 Nm, the allocated torque is less than the original torque requirement (discharging). Therefore, in the high SOC range, and at vehicle speeds below 100 km / h, the SOC will decrease.

[0052] The drive motor outputs positive torque (to drive the wheels) or negative torque (to charge the battery pack) based on the difference between the original required torque of the parallel engine and the engine torque. The drive motor torque = (original required torque of the parallel engine - engine torque) x engine speed ratio / drive motor speed ratio.

[0053] It is worth noting that above 100km, the engine drives the wheels directly. At this point, the engine's operating point is also in the more economical range of the universal characteristic map. The energy transfer path does not need to go through the conversion of the motor and the battery pack. Therefore, the energy distribution method at this time is also quite economical.

[0054] For example, refer to Figure 9 The WLTC cyclic control process includes: Initial stage: SOC=65%, high SOC level, EV mode startup. At this time, high SOC level is defined as: SOC≥65%; Low-speed range: SOC gradually decreases from 65% to around 55%, and the SOC level switches back to the normal SOC level. At this time, the normal SOC level is defined as: SOC < 55%. High-speed section (102~138km / h): SOC not reaching 65%, the switch from normal SOC level to high SOC level is not triggered, and the start-stop module controls the engine start-stop; Ultra-high speed range (acceleration): When first entering the ultra-high speed range, the SOC is around 61%, indicating EV status. Immediately, you need to accelerate to around 120 km / h. Initially, the electric motor works alone, and the SOC gradually decreases. When the SOC drops to the starting map value, the engine starts, gradually switching to engine-driven operation with the electric motor as a secondary driver. The electric motor assists the engine in operating near the optimal economic point. When the first 120 km / h is reached in the ultra-high speed range, the SOC drops to around 51%. At this point, the heavy acceleration (with a large throttle) has ended, the original torque demand decreases, and the engine charges the battery pack. Because the critical line for entering a high SOC level in the ultra-high speed range dips (from 65% to 59%), the battery pack only needs to be charged to 59% to enter the high SOC level. Therefore, when the SOC reaches 59%, the high SOC level is entered. At this point, the vehicle speed is greater than 100 km / h, and the engine starts direct drive.

[0055] Ultra-high speed range (direct drive): High SOC level + vehicle speed ≥ 100km / h, trigger engine direct drive, the battery neither charges nor discharges, the SOC value will maintain a stable value (e.g. 59%) when the engine is in direct drive. At the end of the ultra-high speed section: brake recovery of SOC (e.g., around 6%), the final SOC is consistent with the initial SOC (e.g., 59% + 6% = 65%), and electrical balance is achieved (ΔSOC = 0).

[0056] The threshold values ​​for transitioning from normal SOC level to high SOC level (such as 65% and 59%) and the preset vehicle speed threshold (such as 100km / h) of this solution can be dynamically adjusted based on vehicle parameters (such as battery capacity and energy recovery intensity), and are applicable to different series and parallel hybrid platforms.

[0057] The electric balance control is completely decoupled from driver operation. Even if the driver frequently accelerates / brakes at ultra-high speeds (as long as the speed requirements of WLTC are met), the concave critical line and direct drive strategy can still automatically maintain SOC stability, ensuring that the electric balance result is not affected by human factors.

[0058] Closed-loop control can be achieved solely through SOC range division and torque distribution logic without relying on external calibration data, thus reducing system development costs.

[0059] Furthermore, in one embodiment, the engine start-up threshold and stop-up threshold are determined by a two-dimensional mapping relationship between vehicle speed and throttle signal.

[0060] The engine start-up threshold and engine stop threshold are determined by the two-dimensional mapping relationship between vehicle speed and throttle signal.

[0061] In this embodiment, the engine start-up and stop thresholds are determined through a two-dimensional mapping relationship between vehicle speed and throttle signal. This solves the technical problem in related technologies where it is impossible to guarantee that a single WLTC test cycle will meet the electrical balance requirements. It achieves real-time matching between engine start-up and stop timing and driving conditions, ensuring that the SOC change meets the requirement of ≤1%, thereby avoiding repeated testing and significantly improving testing efficiency. It should be noted that engine start-up and stop are related to the SOC value, but not to the SOC level.

[0062] Furthermore, in one embodiment, the division of the SOC level range includes: when the battery state of charge rises to the high SOC threshold, the SOC level is switched to the high SOC level; when the battery state of charge drops to the low SOC threshold, the SOC level is switched back to the normal SOC level.

[0063] In this embodiment, the division of SOC level ranges includes switching the SOC level to a high SOC level when the battery state of charge rises to a high SOC threshold, and switching the SOC level back to a normal SOC level when the battery state of charge drops to a low SOC threshold. This solves the technical problem of inaccurate SOC state management in related technologies, and makes the SOC level division match the power demand characteristics of WLTC operating conditions. Thus, the SOC level switching can adapt to changes in power demand during WLTC test cycles.

[0064] In one specific embodiment, the SOC level classification includes hysteresis intervals. In the low-to-medium speed stage, when the SOC fluctuates within the range of 55% to 65%, the SOC level remains unchanged. In the ultra-high speed stage, when the SOC fluctuates within the range of 52% to 59%, the SOC level remains unchanged.

[0065] By dividing the SOC level range into hysteresis ranges, the technical problem of frequent switching of SOC near the critical value in related technologies is solved, ensuring that the SOC change in the WLTC test cycle meets the requirement of ≤1%, thereby avoiding repeated testing due to SOC fluctuations and greatly improving testing efficiency.

[0066] Furthermore, in one embodiment, the critical line from normal SOC level to high SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0067] In this embodiment, the critical value for the transition from normal SOC level to high SOC level in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions is a constant value (e.g., 65%).

[0068] Furthermore, in one embodiment, the threshold for transitioning from a high SOC level to a normal SOC level is a horizontal line throughout the WLTC operating conditions.

[0069] In this embodiment, the threshold line for transitioning from a high SOC level to a normal SOC level is a horizontal line. When the threshold line for transitioning from a normal SOC level to a high SOC level is lowered, the distance between the two threshold lines at the lowered point becomes narrower.

[0070] Furthermore, in one embodiment, the critical line for transitioning from a high SOC level to a normal SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0071] The critical line from high SOC level to normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

[0072] In this embodiment, the threshold line from high SOC level to normal SOC level also has a concave feature, which, together with the concave threshold line from normal SOC level to high SOC level, ensures that the distance between the two threshold lines at the concave point remains unchanged.

[0073] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is below the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque or the torque near the optimal operating point that is greater than the original required torque.

[0074] In this embodiment, when the State of Charge (SOC) is at the normal SOC level and the engine is running below 100 km / h, the engine is operated as close to its optimal operating point as possible according to the engine's universal characteristic map. This means the torque allocated to the engine is around Tq_opt. When the original required torque is below 130 Nm, the torque allocated to the engine is greater than its original required torque (charging). When the original required torque is above 130 Nm (requiring significant throttle), the torque allocated to the engine is less than its original required torque (discharging). In WLTC conditions below 100 km / h, there is certainly no significant throttle input, so the original required torque is generally less than 130 Nm, and the battery pack is generally charged.

[0075] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is not lower than the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque or the torque near the optimal operating point that is greater than the original required torque.

[0076] In this embodiment, when the SOC is at the normal SOC level, above 100km / h, regardless of whether the original torque demand of the parallel engine is greater than or less than the optimal torque Tq_opt, the torque allocated to the engine will refer to the universal characteristic map, but will be appropriately greater than the original torque demand of the parallel engine. At this time, the battery pack will be charged, unless the original torque demand of the parallel engine is particularly large, but this exceeds the operating conditions of WLTC.

[0077] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle speed is not lower than the preset high threshold at the high SOC level, the engine is controlled to keep running and drive directly. The torque allocated to the engine is always equal to the original torque required by the parallel engine. At this time, the battery pack neither charges nor discharges (the SOC value remains unchanged). When the vehicle speed is lower than the preset high threshold, torque is allocated based on the universal characteristic map to allocate the engine with the optimal operating point torque or the torque near the optimal operating point. If the throttle is small, the start-stop module will control the engine to stop. In EV mode, the SOC will decrease. If the throttle is large, the torque near the optimal operating point is less than the original torque required by the parallel engine. At this time, the electric motor is required to assist, and the SOC will also decrease.

[0078] In this embodiment, when the SOC is at a high SOC level, above 100km / h, the engine is controlled to run continuously and drive directly. At this time, the torque allocated to the engine is always equal to the original torque required by the parallel engine. The battery pack does not discharge or charge (the SOC value remains unchanged). When the State of Charge (SOC) is at a high SOC level, below 100 km / h, engine torque is allocated according to the engine's universal characteristic map. The torque allocated to the engine is near the optimal torque Tq_opt, allowing the engine to operate near its most economical point. When the original torque requirement is below 130 Nm, the torque allocated to the engine is greater than its original torque requirement, but this will cause the engine to shut down, and the SOC will decrease. In other words, this torque allocation is not used, and there is no charging. When the original torque requirement is above 130 Nm, the torque allocated to the engine is less than its original torque requirement (discharging). Therefore, in the high SOC range, and at vehicle speeds below 100 km / h, the SOC will decrease.

[0079] Furthermore, in one embodiment, the concave feature refers to a concave step, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

[0080] In this embodiment, the SOC critical value at the step = the target SOC value at the end of the WLTC cycle - the SOC value increment after brake energy recovery. The target SOC value is the SOC at the start of the WLTC cycle (typically 65%, determined by the vehicle design); the SOC value increment after brake energy recovery is the SOC increase caused by brake energy recovery obtained through real-vehicle WLTC testing or simulation (typically 5%~7%, measured data is 6%).

[0081] By calculating the difference between the target SOC and the recovered SOC (65%-6%=59%), a precise concave step is set to achieve stable SOC control at ultra-high speeds. This design can be directly integrated into existing hybrid control systems without additional algorithms or hardware, demonstrating strong engineering feasibility.

[0082] Secondly, embodiments of this application also provide a series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions.

[0083] In one embodiment, reference is made to Figure 8 , Figure 8 This is a functional block diagram of an embodiment of the series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions according to this application. Figure 8 As shown, the series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions includes: Input module 1 is used to collect battery state of charge, vehicle speed signal, throttle signal, braking signal and gear signal in real time; Engine start-stop module 2 includes a start control submodule and a stop control submodule, which control the engine to start or stop based on battery charge status, vehicle speed signal, throttle signal and gear signal; SOC classification module 3 is used to divide the battery state of charge into a normal SOC level range and a high SOC level range. The SOC level classification is related to vehicle speed and has hysteresis characteristics. The threshold from the normal SOC level to the high SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC conditions. Torque distribution module 4 distributes engine torque and motor torque according to SOC level, vehicle speed signal, throttle signal, braking signal, and gear signal. In the normal SOC level, the torque allocated to the engine is greater than its original required torque. In the high SOC level, when the vehicle speed is lower than a preset high vehicle speed threshold, the torque allocated to the engine is less than its original required torque. When the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly. The preset high vehicle speed threshold falls into the ultra-high speed range. Execution module 5 is used to control engine start / stop and torque distribution.

[0084] Braking energy recovery module 6 is used to perform energy recovery during braking.

[0085] In this embodiment, a concave design is used to bridge the gap between the normal SOC level and the high SOC level in the ultra-high-speed range (e.g., the critical point drops from 65% to 59%). This precisely controls the automatic switch to a high SOC level after the SOC has been charged in the ultra-high-speed range (e.g., the SOC value rises to 59%). Combined with the triggering of the engine direct drive mode when the vehicle speed exceeds a preset high-speed threshold (e.g., ≥100km / h), the SOC remains stable during the direct drive phase (e.g., maintained at 59%, with no charging or discharging losses). During the braking phase in the ultra-high-speed range, energy recovery replenishes some SOC (approximately 6%), ultimately allowing the SOC to accurately return to its initial value (e.g., recovering 6% from 59%, returning to the initial value of 65%, ΔSOC=0). This achieves for the first time that the WLTC cycle test meets the electrical balance requirements in a single test (e.g., SOC start-stop difference ≤2.6%, |energy change| ≤1%), avoiding the resource waste of multiple tests required by traditional technologies and significantly reducing testing costs and cycles.

[0086] Furthermore, in one embodiment, the engine start-up threshold and stop-up threshold are determined by a two-dimensional mapping relationship between vehicle speed and throttle signal.

[0087] The start-up threshold and stop-down threshold are determined by the two-dimensional mapping relationship between vehicle speed and throttle signal.

[0088] In this embodiment, the engine start-up threshold and stop-down threshold are determined by the two-dimensional mapping relationship between vehicle speed and throttle signal. This solves the technical problem in related technologies that it is impossible to guarantee that a single WLTC test cycle will meet the electrical balance requirements. It realizes real-time matching between engine start-up and stop timing and driving conditions, ensuring that the SOC change meets the requirement of ≤1%, thereby avoiding repeated testing and greatly improving testing efficiency.

[0089] Furthermore, in one embodiment, the division of the SOC level range includes: when the battery state of charge rises to the high SOC threshold, the SOC level is switched to the high SOC level; when the battery state of charge drops to the low SOC threshold, the SOC level is switched back to the normal SOC level.

[0090] In this embodiment, the division of SOC level ranges includes switching the SOC level to a high SOC level when the battery state of charge rises to a high SOC threshold, and switching the SOC level back to a normal SOC level when the battery state of charge drops to a low SOC threshold. This solves the technical problem of inaccurate SOC state management in related technologies, and makes the SOC level division match the power demand characteristics of WLTC operating conditions. Thus, the SOC level switching can adapt to changes in power demand during WLTC test cycles.

[0091] Furthermore, in one embodiment, the critical line from normal SOC level to high SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0092] In this embodiment, the critical value for the transition from normal SOC level to high SOC level in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions is a constant value (e.g., 65%).

[0093] Furthermore, in one embodiment, the threshold for transitioning from a high SOC level to a normal SOC level is a horizontal line throughout the WLTC operating conditions.

[0094] In this embodiment, the threshold line for transitioning from a high SOC level to a normal SOC level is a horizontal line. When the threshold line for transitioning from a normal SOC level to a high SOC level is lowered, the distance between the two threshold lines at the lowered point becomes narrower.

[0095] Furthermore, in one embodiment, the critical line for transitioning from a high SOC level to a normal SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

[0096] The critical line from high SOC level to normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

[0097] In this embodiment, the threshold line from high SOC level to normal SOC level also has a concave feature, which, together with the concave threshold line from normal SOC level to high SOC level, ensures that the distance between the two threshold lines at the concave point remains unchanged.

[0098] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is below the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque or the torque near the optimal operating point that is greater than the original required torque.

[0099] In this embodiment, when the State of Charge (SOC) is at the normal SOC level and the engine is running below 100 km / h, the engine is operated as close to its optimal operating point as possible according to the engine's universal characteristic map. This means the torque allocated to the engine is around Tq_opt. When the original required torque is below 130 Nm, the torque allocated to the engine is greater than its original required torque (charging). When the original required torque is above 130 Nm (requiring significant throttle), the torque allocated to the engine is less than its original required torque (discharging). In WLTC conditions below 100 km / h, there is certainly no significant throttle input, so the original required torque is generally less than 130 Nm, and the battery pack is generally charged.

[0100] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is not lower than the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque or the torque near the optimal operating point that is greater than the original required torque.

[0101] In this embodiment, when the SOC is at the normal SOC level, above 100km / h, regardless of whether the original torque demand of the parallel engine is greater than or less than the optimal torque Tq_opt, the torque allocated to the engine will refer to the universal characteristic map, but will be appropriately greater than the original torque demand of the parallel engine. At this time, the battery pack will be charged, unless the original torque demand of the parallel engine is particularly large, but this exceeds the operating conditions of WLTC.

[0102] Furthermore, in one embodiment, the step of allocating engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle speed is not lower than the preset high threshold at the high SOC level, the start-stop module 2 controls the engine to keep running, and the torque distribution module 4 controls the engine to drive directly. The torque distributed to the engine is always equal to the original torque required by the parallel engine. At this time, the battery pack neither charges nor discharges (the SOC value remains unchanged). When the vehicle speed is lower than the preset high threshold, torque distribution is performed based on the universal characteristic map to allocate the engine with the optimal operating point torque or the torque near the optimal operating point. If the throttle is small, the start-stop module will control the engine to stop, and the EV will drive, and the SOC will decrease. If the throttle is large, the torque near the optimal operating point is less than the original torque required by the parallel engine. At this time, the electric motor is needed to assist, and the SOC will also decrease.

[0103] In this embodiment, when the SOC is at a high SOC level, above 100km / h, the engine is controlled to run continuously and drive directly. At this time, the torque allocated to the engine is always equal to the original torque required by the parallel engine. The battery pack does not discharge or charge (the SOC value remains unchanged). When the State of Charge (SOC) is at a high SOC level, below 100 km / h, engine torque is allocated according to the engine's universal characteristic map. The torque allocated to the engine is near the optimal torque Tq_opt, allowing the engine to operate near its most economical point. When the original torque requirement is below 130 Nm, the torque allocated to the engine is greater than its original torque requirement, but this will cause the engine to shut down, and the SOC will decrease. In other words, this torque allocation is not used, and there is no charging. When the original torque requirement is above 130 Nm, the torque allocated to the engine is less than its original torque requirement (discharging). Therefore, in the high SOC range, and at vehicle speeds below 100 km / h, the SOC will decrease.

[0104] Furthermore, in one embodiment, the concave feature refers to a concave step, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

[0105] In this embodiment, the SOC critical value at the step = the target SOC value at the end of the WLTC cycle - the SOC value increment after brake energy recovery. The target SOC value is the SOC at the start of the WLTC cycle (typically 65%, determined by the vehicle design); the SOC value increment after brake energy recovery is the SOC increase caused by brake energy recovery obtained through real-vehicle WLTC testing or simulation (typically 5%~7%, measured data is 6%).

[0106] By calculating the difference between the target SOC and the recovered SOC (65%-6%=59%), a precise concave step is set to achieve stable SOC control at ultra-high speeds. This design can be directly integrated into existing hybrid control systems without additional algorithms or hardware, demonstrating strong engineering feasibility.

[0107] The beneficial effects of the technical solution of this invention are as follows: To achieve optimal fuel economy, torque distribution is based on an optimal engine universal characteristic map, ensuring the engine operates at its best operating point. At high SOC levels above 100km / h, direct engine drive mode is used to avoid energy conversion losses during battery charging and discharging. Above 100km / h, the engine operates with high efficiency and an efficient energy transfer path, significantly reducing fuel consumption.

[0108] To achieve single-cycle WLTC electrical balancing, specifically through the coordinated control of input module 1, engine start-stop module 2, SOC range division module, and torque distribution module 4, the system ensures that the SOC change during the WLTC test cycle is ≤2.6% (|ΔEreess / Energytotal| ≤ 1%), meeting the electrical balancing requirements. This avoids the resource waste of traditional methods requiring 2-3 repeated tests, significantly reducing testing costs and time.

[0109] It exhibits strong robustness; specifically, the electric balance control is unaffected by changes in vehicle speed, ensuring consistent test results. It is also unaffected by differences in driver operation, with minimal fluctuations in test results among different drivers. By adjusting the start / stop points and engine torque distribution strategy, an appropriate time can be reserved for entering engine direct drive mode; the length of the direct drive time directly reflects the system's robustness.

[0110] Through the systematic design of the above-mentioned innovative points, this invention achieves precise, efficient, and robust electric balance control under WLTC conditions, providing an efficient and reliable testing solution for the development of hybrid vehicles.

[0111] The functions of each module in the series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions correspond to the steps in the embodiment of the series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions. Their functions and implementation processes will not be described in detail here.

[0112] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0113] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. A process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequential order, nor do they limit "first," "second," and "third" to different types.

[0114] In the description of the embodiments in this application, terms such as "exemplary," "as," or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "as," or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "as," or "for example" is intended to present the relevant concepts in a specific manner.

[0115] In the description of the embodiments of this application, unless otherwise stated, " / " means "or", such as A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships, such as A and / or B, which can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0116] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0117] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0118] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions, characterized in that, The method includes: Real-time collection of battery state of charge, vehicle speed signal, throttle signal, braking signal and gear signal; The engine is started or stopped based on the battery state of charge, vehicle speed signal, throttle signal and gear signal; The battery state of charge is divided into a normal SOC level range and a high SOC level range. The SOC level division is related to vehicle speed and has hysteresis characteristics. The critical line from the normal SOC level to the high SOC level shows a concave feature in the ultra-high speed range of WLTC conditions. Engine torque and electric motor torque are distributed according to SOC level, vehicle speed signal, throttle signal, braking signal and gear signal; At a normal SOC level, the torque allocated to the engine is greater than its original required torque; at a high SOC level, when the vehicle speed is lower than a preset high vehicle speed threshold, the torque allocated to the engine is less than its original required torque, and when the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly; the preset high vehicle speed threshold falls into the ultra-high speed range.

2. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The engine start-up threshold and stop-down threshold are determined by a two-dimensional mapping relationship between vehicle speed and throttle signal.

3. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The division of the SOC level range includes: when the battery state of charge rises to the high SOC threshold, the SOC level is switched to the high SOC level; when the battery state of charge drops to the low SOC threshold, the SOC level is switched back to the normal SOC level.

4. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The critical line from normal SOC level to high SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

5. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The threshold for transitioning from a high SOC level to a normal SOC level is a horizontal line throughout the entire WLTC operating condition.

6. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The critical line from high SOC level to normal SOC level is a horizontal line in the low-speed, medium-speed, and high-speed ranges of WLTC operating conditions.

7. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 6, characterized in that, The critical line from high SOC level to normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

8. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The process of distributing engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is below the preset high threshold, torque is allocated based on the universal characteristic map to allocate the engine with the optimal operating point torque that is greater than the original required torque.

9. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The process of distributing engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the vehicle is at a normal SOC level and the vehicle speed is not lower than the preset high threshold, torque is allocated based on the universal characteristic map to allocate the engine with the optimal operating point torque that is greater than the original required torque.

10. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The process of distributing engine torque and electric motor torque based on SOC level, vehicle speed signal, throttle signal, and braking signal specifically includes the following steps: When the SOC level is high and the vehicle speed is lower than the preset high threshold, torque is allocated based on the universal characteristic map, and the engine is allocated the optimal operating point torque, which is less than the original required torque.

11. The series-parallel non-plug-in hybrid electric balance control method based on WLTC operating conditions as described in claim 1, characterized in that, The concave feature refers to a step-down depression, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

12. A series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions, characterized in that, The system includes: The input module is used to collect battery state of charge, vehicle speed signal, throttle signal, braking signal and gear signal in real time; The engine start-stop module includes a start control submodule and a stop control submodule, which control the engine to start or stop based on the battery charge status, vehicle speed signal, throttle signal and gear signal; The SOC classification module is used to divide the battery state of charge into a normal SOC level range and a high SOC level range. The SOC level classification is related to vehicle speed and has hysteresis characteristics. The critical line from the normal SOC level to the high SOC level shows a concave feature in the ultra-high speed range of WLTC conditions. The torque distribution module distributes engine torque and motor torque according to SOC level, vehicle speed signal, throttle signal, braking signal, and gear signal. At normal SOC level, the torque distributed to the engine is greater than its original required torque. At high SOC level, when the vehicle speed is lower than a preset high vehicle speed threshold, the torque distributed to the engine is less than its original required torque. When the vehicle speed is not lower than the preset high vehicle speed threshold, the engine drives directly. The preset high vehicle speed threshold falls within the ultra-high speed range. The execution module is used to control engine start / stop and torque distribution.

13. The series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions as described in claim 12, characterized in that, The critical line from high SOC level to normal SOC level exhibits a concave characteristic in the ultra-high speed range of WLTC operating conditions.

14. The series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions as described in claim 12, characterized in that, The concave feature refers to a step-down depression, and the SOC critical value at the step is set according to the difference between the target SOC value at the end of the WLTC operating condition and the SOC value after brake energy recovery.

15. The series-parallel non-plug-in hybrid electric balance control system based on WLTC operating conditions as described in claim 12, characterized in that, The system also includes a braking energy recovery module for performing energy recovery during braking.

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