A soc dynamic control method and system for extended-range electric vehicles

Abstract

The application relates to the technical field of control of range-extended electric vehicles, and particularly discloses a SOC dynamic control method and system for a range-extended electric vehicle, which comprises the following steps: determining a driving route according to a destination and a current position of the vehicle, and identifying a continuous undulating section with a long uphill section followed by a long downhill section; if a SOC target percentage at the start of the continuous undulating section is less than or equal to 100%, the SOC of the vehicle is controlled to be not lower than the SOC target percentage before the vehicle reaches the start of the continuous undulating section; otherwise, the driving speed of the vehicle is reduced, the SOC target percentage is recalculated; until the SOC target percentage is less than or equal to 100% or the driving speed of the vehicle is reduced to the minimum allowable speed of the long uphill section. The application seeks a feasible control scheme through iterative reduction of the driving speed and re-reverse recursion, and the driving safety and traffic feasibility are considered, so that the vehicle is prevented from being trapped halfway due to power feeding.

Description

Technical Field

[0001] This invention relates to the field of range-extended electric vehicle control technology, and in particular to a SOC dynamic control method and system for range-extended electric vehicles. Background Technology

[0002] With the development of intelligent connected vehicle technology, range-extended electric vehicles (REEVs), thanks to their pure electric drive characteristics and extended driving range provided by range extenders, have gradually entered complex operating scenarios such as mountain roads. However, the continuous uphill and downhill conditions commonly encountered on mountain roads pose a serious challenge to the management of the State of Charge (SOC) of these vehicles' power batteries, mainly in the following two aspects.

[0003] First, during long-distance uphill driving, the continuous steep gradient resistance requires the drive motor to output higher power. The driving energy of a range-extended electric vehicle primarily comes from the battery, while the power output of the onboard range extender is typically much lower than the rated power of the drive motor. If the battery is already depleted or at a low charge level before entering a long uphill section, the battery management system (BMS) will limit the peak power output of the drive motor to protect the battery. This forces the vehicle to slow down or even stop while waiting for the range extender to charge the battery, severely impacting normal vehicle use and traffic safety.

[0004] Secondly, in long downhill driving conditions, range-extended electric vehicles typically rely on regenerative braking of the drive motor for auxiliary braking, providing both deceleration safety and energy recovery benefits. For cost control reasons, these vehicles are usually not equipped with additional auxiliary braking devices such as hydraulic retarders or eddy current retarders. However, once the battery's state of charge (SOC) is saturated, the BMS safety strategy will prohibit the regenerative braking energy from charging, resulting in a complete loss of auxiliary braking effectiveness. At this point, relying solely on mechanical friction braking makes the brakes highly susceptible to overheating and brake fade, seriously threatening driving safety.

[0005] To address the aforementioned issues, several SOC management solutions based on route prediction have been proposed in recent years. For example, Chinese invention patent CN113071335A discloses an energy control method for range-extended vehicles, which acquires information about the road the vehicle is about to travel on; determines the road conditions based on the road information; when the road conditions include downhill, the method controls the vehicle's range extender to stop charging the vehicle's battery, enabling energy braking, or primarily energy braking, to be used during downhill driving, reducing the duration of mechanical braking. This effectively avoids the occurrence of mechanical brake failure and wear due to excessive temperature during mechanical braking on downhill roads.

[0006] A more critical and under-recognized issue is that typical mountain roads, such as winding mountain roads, often present continuous operating conditions with long uphill climbs followed immediately by long downhill climbs. In this scenario, if only a strategy of unidirectionally increasing the State of Charge (SOC) before the uphill climb is adopted, the battery will be charged to a high state of charge after climbing, causing the SOC to quickly reach its upper limit during the subsequent long downhill climb, prematurely disabling regenerative braking and resulting in braking safety risks and energy waste. Conversely, if only a strategy of unidirectionally decreasing the SOC before the downhill climb is adopted, the drive power may be limited due to insufficient battery power during the uphill climb. Existing single-line control logic cannot reconcile the contradictory needs in these two directions, lacking a solution that couples the bidirectional constraints of uphill and downhill driving. Summary of the Invention

[0007] The present invention aims to solve the above-mentioned problems. To this end, the present invention provides a method and system for dynamic SOC control of range-extended electric vehicles.

[0008] This invention provides a dynamic SOC control method for range-extended electric vehicles, the technical solution of which includes: S1: Obtain the destination of the range-extended electric vehicle; S2: Based on the destination and the vehicle's current location, determine the driving route, identify long uphill and long downhill sections in the driving route, and determine the continuous undulating road sections that are followed by long downhill sections after long uphill sections. If there is a transition section between adjacent long uphill and long downhill sections, and the length of the transition section is less than a threshold, the adjacent long uphill and long downhill sections are identified as continuous undulating road sections where a long uphill section is followed by a long downhill section. By relaxing the theoretical threshold, we obtain the threshold value. The formula for calculating the theoretical threshold is: in, The theoretical threshold, The SOC adjustment range for the transition phase. This refers to the total electrical energy when the power battery's SOC is 100%. V represents the power output of the battery in the transition phase of a range-extended electric vehicle when the range extender is off and the vehicle is driven in pure electric mode. S3: Based on the slope, length, and vehicle speed of the driving route, calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections where a long uphill section is followed by a long downhill section; and perform battery control for the range-extended electric vehicle based on the target SOC percentage. If the SOC target percentage at the starting point of a continuous undulating road section is less than or equal to 100%, then the vehicle's SOC shall be controlled to be no less than the SOC target percentage before reaching the starting point of the continuous undulating road section. If the SOC target percentage at the starting point of a continuous undulating road segment is greater than 100%, the vehicle speed on the long uphill section of the continuous undulating road segment will be reduced by a preset step size, and the SOC target percentage of the long uphill section will be calculated. The reverse recursion will be performed to calculate the SOC target percentage at the starting point of the new continuous undulating road segment. This process continues until the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%, or the vehicle speed is reduced to the minimum allowable speed for the long uphill section. In step S3, the calculation process for the SOC target percentage corresponding to the continuous undulating road segment following a long uphill section and then a long downhill section is as follows: S3.31: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill section in the continuous undulating road segment; S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion; wherein, the reverse recursion is: for each long uphill and long downhill section of the continuous undulating road segment, the SOC target percentage of the starting point of each section is calculated from back to front; after a vehicle passes through a long uphill section, its SOC is reduced by the SOC target percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the SOC target percentage corresponding to that long downhill section.

[0009] Furthermore, in step S2, long uphill sections and long downhill sections in the driving route are first identified, and then, based on the identified long uphill sections and long downhill sections, it is determined whether there are continuous undulating road sections where a long uphill section is followed by a long downhill section.

[0010] Furthermore, in step S2, road sections with an average slope greater than or equal to 2% and a continuous length greater than or equal to 5km that show an overall upward trend are classified as long uphill road sections; among the long uphill road sections, road sections with a slope less than 2% and a length not exceeding 2km, or road sections with a downward trend and a length not exceeding 1km, are ignored. Road sections with an average gradient of 2% or greater and a continuous length of 5km or greater that show a continuous downward trend are classified as long downhill sections. Among long downhill sections, sections with a gradient of less than 2% and a length of no more than 2km, or sections with an upward gradient and a length of no more than 1km, are disregarded.

[0011] Furthermore, in step S3, the calculation process for the SOC target percentage corresponding to the long uphill road section is as follows: S3.11: Calculate the work done by a vehicle overcoming gradient resistance on a long uphill section based on its gradient and length; S3.12: Calculate the total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section based on the gradient and vehicle speed. S3.13: Calculate the estimated time required for a vehicle to traverse a long uphill section based on the gradient of the uphill section and the vehicle's speed; S3.14: Based on the work done by the vehicle to overcome the gradient resistance on the long uphill section, the total work required for the vehicle to overcome rolling resistance and air resistance on the long uphill section, and the estimated time required for the vehicle to pass through the long uphill section, calculate the target percentage of SOC corresponding to the long uphill section. The battery control strategy for range-extended electric vehicles is to control the State of Charge (SOC) to be no less than the target SOC percentage before the vehicle reaches the starting point of a long uphill section.

[0012] Furthermore, the process of calculating the work done by vehicles overcoming gradient resistance on a long uphill section is as follows: Divide the long uphill section into equal parts by distance to obtain multiple equal segments. The number of equal parts is the rounded integer of the total length of the uphill section. Calculate the sum of the work done by vehicles overcoming gradient resistance in all equal segments to obtain the total work done by vehicles overcoming gradient resistance on the long uphill section.

[0013] Furthermore, in step S3, the target percentage of SOC corresponding to the long downhill section is calculated based on the height difference between the start and end points of the long downhill section and the vehicle speed. The battery control strategy for range-extended electric vehicles is to control the State of Charge (SOC) to be below the target SOC percentage before the vehicle reaches the starting point of a long downhill section.

[0014] Furthermore, in step S1, if the destination is successfully obtained, step S2 is executed; otherwise, step S4 is executed. S4: Starting from the vehicle's current position, along the current driving direction, obtain the road slope within the preset prediction range ahead; when, based on step S2, it is determined that there is a long uphill section, a long downhill section, or a continuous undulating road section where a long uphill section is followed by a long downhill section, an inquiry is sent to the driver; if the driver gives an affirmative answer or no answer is received, then based on step S3, the SOC target percentage is calculated, and battery control of the range-extended electric vehicle is performed.

[0015] This invention also provides a SOC dynamic control system for range-extended electric vehicles, the technical solution of which includes: The destination acquisition module is used to acquire the destination of the range-extended electric vehicle. The long slope determination module is used to determine the driving route based on the destination and the current location of the vehicle, and to identify long uphill and long downhill sections in the driving route, and to determine the continuous undulating road sections that are followed by long downhill sections after the long uphill sections. If there is a transition section between adjacent long uphill and long downhill sections, and the length of the transition section is less than a threshold, the adjacent long uphill and long downhill sections are identified as continuous undulating road sections where a long uphill section is followed by a long downhill section. The SOC calculation and battery control module is used to calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections followed by long downhill sections based on the slope, length, and vehicle speed of the driving route; and to perform battery control of the range-extended electric vehicle based on the target SOC percentage. If the SOC target percentage at the starting point of a continuous undulating road section is less than or equal to 100%, then the vehicle's SOC shall be controlled to be no less than the SOC target percentage before reaching the starting point of the continuous undulating road section. If the SOC target percentage at the starting point of a continuous undulating road segment is greater than 100%, the vehicle speed on the long uphill section of the continuous undulating road segment will be reduced by a preset step size, and its SOC target percentage will be calculated. The reverse recursion will be performed to calculate the SOC target percentage at the starting point of the new continuous undulating road segment. This process continues until the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%, or the vehicle speed is reduced to the minimum allowable speed for the long uphill section. In step S3, the calculation process for the SOC target percentage corresponding to the continuous undulating road segment following a long uphill section and then a long downhill section is as follows: S3.31: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill section in the continuous undulating road segment; S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion; wherein, the reverse recursion is: for each long uphill and long downhill section of the continuous undulating road segment, the SOC target percentage of the starting point of each section is calculated from back to front; after a vehicle passes through a long uphill section, its SOC is reduced by the SOC target percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the SOC target percentage corresponding to that long downhill section.

[0016] Furthermore, it also includes a self-judgment control strategy module, which is used to obtain the road slope within a preset prediction range ahead, starting from the vehicle's current position and along the current driving direction; when the long slope judgment module determines that there is a long uphill section, a long downhill section, or a continuous undulating road section where a long uphill section is followed by a long downhill section, it sends a query to the driver; if the driver gives an affirmative answer or no answer is received, the SOC target percentage is calculated based on the SOC calculation and battery control module, and the battery control of the range-extended electric vehicle is performed; The destination acquisition module is also used to invoke the self-judgment control strategy module when destination acquisition fails.

[0017] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: (1) For continuous undulating road sections where a long uphill section is followed by a long downhill section, this invention couples the uphill energy demand constraint with the downhill energy recovery constraint. The SOC control target at the starting point of the continuous undulating road section is determined by reverse recursion. While ensuring the uphill dynamics, sufficient battery capacity space is reserved for downhill regenerative braking, thus realizing bidirectional coordinated control of SOC under continuous undulating conditions.

[0018] (2) When the SOC at the starting point of the continuous undulating road segment obtained by reverse recursion exceeds 100% (i.e., it is not safe to pass at the original planned speed), the present invention seeks a feasible control scheme by iteratively reducing the vehicle speed and recursively recursing, and prompts the driver to drive at the adjusted speed; if it is still not feasible to reduce the vehicle speed to the minimum allowable speed, the driver is prompted to replan the route, and the battery control is executed with the SOC corresponding to the minimum allowable speed as the charging target, so as to take into account driving safety and passability under extreme conditions and avoid the vehicle being stranded due to power depletion.

[0019] (3) This invention targets long uphill sections and uses the conversion relationship between slope resistance, rolling resistance, air resistance and the efficiency of each system to estimate the minimum state of charge of the power battery required to pass through the uphill section. It also starts the range extender in advance to store energy for the power battery, avoiding the problem of the vehicle slowing down or even stopping to wait for charging due to the BMS limiting the power output of the drive motor when the power battery is depleted or at low charge. This ensures that the vehicle passes through the uphill section smoothly according to the predetermined driving intention, and protects the traffic safety and efficiency of mountain roads.

[0020] (4) This invention targets long downhill sections, estimates the amount of electrical energy that the energy recovery system can recover during the downhill process, and sets a SOC upper limit control target accordingly. When the SOC of the power battery is about to reach the control target, the range extender stops working or the external charging is interrupted, ensuring that the power battery has enough capacity to store the recovered electrical energy throughout the downhill process, so that the regenerative braking auxiliary braking function remains effective, and there is no need to equip auxiliary braking devices such as hydraulic retarder and electric eddy current retarder, which reduces the overall vehicle cost.

[0021] (5) This invention adopts a dual-mode control architecture that combines navigation control strategy and self-judgment control strategy: when the driver inputs the navigation destination, the long slope condition is accurately identified based on the planned route; when no destination is input, the road elevation information within the preset prediction range ahead is predicted based on a high-precision map, and the driver's driving intention is asked. This dual-mode architecture is not limited by whether the driver uses navigation, can adapt to different driving habits and actual driving needs, expands the applicable scenarios of the control strategy, and improves the accuracy of control and human-computer interaction experience.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the method provided by the present invention.

[0025] Figure 2 This is a schematic diagram of a driving route in an area with undulating terrain, provided by the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit the scope of this invention.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0028] The following is combined Figure 1 and Figure 2 The present invention will be further described in detail below, including a SOC dynamic control method and system for a range-extended electric vehicle: In this embodiment, as Figure 1 As shown, a dynamic SOC control method for a range-extended electric vehicle is provided, comprising the following steps: S1: Obtain the destination of the range-extended electric vehicle; if the destination is successfully obtained, proceed to step S2, otherwise proceed to step S4.

[0029] After the range-extended electric vehicle starts, it first determines whether the driver is using the in-vehicle navigation to go to the destination. If the driver enters the destination in the in-vehicle navigation, the destination information can be obtained, and the navigation control strategy is adopted, executing step S2; if the driver does not enter the destination in the in-vehicle navigation, the destination information cannot be obtained, and the self-judgment control strategy is adopted, executing step S4.

[0030] Drivers can choose to enable or disable the self-judgment control strategy according to their personal needs.

[0031] S2: Based on the destination and the vehicle's current location, determine the driving route and identify long uphill and downhill sections in the driving route, and determine the continuous undulating road sections that are followed by long downhill sections after the long uphill sections.

[0032] In this embodiment, road sections with an average slope greater than or equal to 2% and a continuous length greater than or equal to 5km that show a continuous upward trend are classified as long uphill road sections. Among the long uphill road sections, road sections with a slope less than 2% and a length not exceeding 2km, or road sections with a downward trend and a length not exceeding 1km, are ignored (these road sections are removed and not included in subsequent calculations).

[0033] Road sections with an average gradient of 2% or greater and a continuous length of 5km or greater that show a continuous downward trend are classified as long downhill sections. Among long downhill sections, sections with a gradient of less than 2% and a length of no more than 2km, or sections with an upward gradient and a length of no more than 1km, are disregarded.

[0034] In this embodiment, when identifying long uphill and downhill sections, the first step is to filter out ascending and descending sections with a gradient of 2% or greater based on the gradient of the driving route. Then, from these ascending and descending sections, continuous uphill and continuous descending sections are selected. For each continuous uphill section, the segments between adjacent uphill sections are considered negligible if they have a gradient of less than 2% and a length not exceeding 2km, or if they have a descending gradient and a length not exceeding 1km. If all segments between adjacent uphill sections of a continuous uphill section are negligible, then this continuous uphill section is considered as a single continuous uphill sub-segment. By default, negligible segments are removed from the continuous uphill sub-segments and are not considered in subsequent steps. If a continuous uphill section contains non-negligible segments, it must be split into multiple continuous uphill sub-segments. Finally, based on a continuous length of 5km or more, it is determined whether a continuous uphill section is a long uphill section. A similar method is used to determine continuous downhill sections, thus identifying long downhill sections.

[0035] It should be noted that, since negligible road segments have been eliminated, the slope value at any point within a long uphill section is positive (uphill direction), and the slope value at any point within a long downhill section is negative (downhill direction). However, even after eliminating negligible road segments, there may still be local minor slope fluctuations in actual roads, making it extremely difficult to ensure that the slope value at any point is positive (or negative) in practice. Therefore, this embodiment utilizes in-vehicle navigation to determine the driving route and obtains the slope information of the driving route from the in-vehicle navigation system; since local minor slope fluctuations in actual roads are not given in the above slope information, this embodiment ignores these local minor slope fluctuations.

[0036] Based on the planned driving route, determine whether there are long downhill and uphill sections between the vehicle's current location and the destination. For areas with undulating terrain, it is also necessary to determine whether there are continuous undulating sections where a long uphill section is followed by a long downhill section.

[0037] After identifying long uphill and downhill sections, determine whether there exists a continuous undulating road segment where a long uphill section is followed by a long downhill section. It's important to note that if a transition section exists between adjacent long uphill and downhill sections, and the length of this transition section is less than a threshold, then a continuous undulating road segment where a long uphill section is followed by a long downhill section is considered to exist, and this adjacent long uphill and downhill section is classified as such.

[0038] In this embodiment, the threshold for the transition segment is the minimum driving distance required for the range-extended electric vehicle to complete the transition from the target SOC percentage on a long uphill climb to the target SOC percentage on a long downhill climb. The calculation formula is as follows: in, The theoretical threshold, The SOC adjustment range for the transition period is generally taken as 2% to 5%; This refers to the total electrical energy when the power battery's SOC is 100%. V represents the power output of the battery in the transition phase of a range-extended electric vehicle when the range extender is off and the vehicle is driven in pure electric mode. V is the vehicle speed.

[0039] By relaxing the theoretical threshold, we obtain the threshold value. For example, the threshold value can be set to 1.1 times the theoretical threshold value.

[0040] For example, When the slope is set to 2.5%, the gradient of the transition section is set to 0, and the vehicle speed is set to 80 km / h.

[0041] For a certain model of range-extended electric vehicle, with a total vehicle mass of 2.5 tons and a total battery capacity of 30 kWh, the resistance work to be overcome per meter of travel on a straight road is approximately 504.26 joules, which is the sum of rolling resistance and air resistance. Therefore, the theoretical travel range for this model can be calculated to be approximately 4.55 km. The threshold is set to 5 km.

[0042] For another type of range-extended electric vehicle (electric heavy truck), with a total vehicle mass of 49 tons and a total battery capacity of 300 kWh, the resistance work to be overcome per meter of travel on a straight road is the sum of rolling resistance and air resistance, approximately 5869 joules. Therefore, the theoretical travel threshold for this model can be calculated to be approximately 3.9 km. The threshold is set at 4.3 km.

[0043] like Figure 2As shown, point O represents the vehicle's current position. Segments AB and CD are long uphill sections, while segments B'-C and DE are long downhill sections. Segments CD and DE form a continuous undulating road segment following a long uphill section. Segment B-B' is the transition segment between segments AB and B'-C. If the length of segment B-B' is less than a threshold, then segments AB and B'-C form a continuous undulating road segment following a long uphill section; if the length of segment B-B' is greater than or equal to the threshold, then segments AB and B'-C do not form a continuous undulating road segment following a long uphill section.

[0044] S3: Based on the slope, length, and vehicle speed of the driving route, calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections followed by long downhill sections; and perform battery control of the range-extended electric vehicle based on the target SOC percentage.

[0045] S3.1: Calculate the target percentage of SOC for the long uphill section based on its gradient, length, and vehicle speed.

[0046] S3.11: Calculate the work done by a vehicle overcoming gradient resistance on a long uphill section (excluding the two types of sections that are ignored) based on the gradient and length of the long uphill section.

[0047] To simplify calculations, this embodiment divides the long uphill section into multiple equal segments based on distance. The number of segments is the rounded integer of the total length of the uphill section (e.g., if the total length is 5.2 km, it is divided into 5 segments, each 1.04 km long). The sum of the work done by the vehicle against gradient resistance in all segments is calculated to obtain the total work done by the vehicle against gradient resistance on the long uphill section. The calculation formula is: In the formula, The total work done by a vehicle to overcome the resistance of a gradient on a long uphill section; Let be the gradient resistance of the vehicle within the i-th equal segment; Let be the length of the i-th equal segment; n is the total number of equal segments.

[0048] In this embodiment, rounding is calculated based on kilometers. Since the equal segments are divided sufficiently small (approximately 1 km), each segment can be simplified to a standard slope, during which the slope resistance remains constant. The calculation formula is: In the formula, M is the total mass of the range-extended electric vehicle; It is the acceleration due to gravity; The height difference of the i-th equal segment can be obtained from a high-precision map, and the unit is meters.

[0049] S3.12: Calculate the total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section based on the gradient and vehicle speed. The calculation formula is as follows: In the formula, The total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section; The rolling resistance can be taken as 0.01; s is the total length of the long uphill section. The density of air can be taken as 1.2 kg per cubic meter; The frontal area of ​​the car; V is the air resistance coefficient of the car, which is a test value. If there is no test value for a certain model, it can be estimated as 0.35 for light vehicles and 0.45 for medium and heavy vehicles; V is the vehicle speed.

[0050] S3.13: Calculate the estimated time required for a vehicle to traverse a long uphill section based on its gradient and speed. The formula is as follows: In the formula, The time required for a vehicle to traverse a long uphill section; Let be the vehicle speed in the i-th equally divided segment. The principle for determining the speed limit is the smaller of the speed limit for long uphill sections and 90% of the vehicle's maximum speed in the current mode. If the speed limits at the start and end of such sections are different, the larger value is used for contingency. The speed limit for long uphill sections can be obtained from a high-precision map. The vehicle's current mode is, for example, economy mode or climbing mode.

[0051] S3.14: Based on the work done by the vehicle to overcome the slope resistance on the long uphill section, the total work required for the vehicle to overcome rolling resistance and air resistance on the long uphill section, and the estimated time required for the vehicle to pass through the long uphill section, the total electrical energy that the power battery should store before climbing the hill is calculated, and then the SOC target percentage corresponding to the long uphill section is calculated.

[0052] Energy consumed by a range-extended electric vehicle going uphill ( + This is equivalent to the mechanical energy converted from electrical energy consumed by the power battery. The electrical energy that the power battery can consume is the sum of the electrical energy supplemented by the range extender and the electrical energy available for use by the battery itself. In the formula, This refers to the continuous rated power output of the range extender to the power battery, expressed in kilowatts. This represents the total electrical energy that the power battery should store before climbing a hill. Electrical energy stored when the power output is limited by the power battery protection strategy; The conversion efficiency from electrical energy in the power battery to mechanical energy in the wheel is given by the measured value of the vehicle. If no corresponding value is available, 0.85 can be used.

[0053] After converting the above formula, we get: .

[0054] Therefore, the corresponding long uphill section can be determined. The minimum value, Dividing the minimum value of the power battery by the capacity of the power battery, we can obtain the minimum state of charge that the power battery of the range-extended electric vehicle should reach before starting to climb the hill, that is, the target SOC percentage corresponding to the long uphill section, for example, SOC=68%.

[0055] The vehicle's battery control strategy needs to be temporarily adjusted as follows: before the vehicle reaches the starting point of the long uphill section, its SOC should be controlled to be no lower than the target SOC percentage; if it is lower than the target SOC percentage, the range extender should be activated immediately to charge the vehicle to ensure that it is always no lower than that percentage; if the theoretically calculated percentage is greater than 100%, since it is practically impossible to be greater than 100%, it means that the vehicle cannot maintain the original planned speed to pass through this uphill section and needs to reduce its speed.

[0056] S3.2: Calculate the target SOC percentage for the long downhill section based on the height difference between the start and end points of the long downhill section and the vehicle speed.

[0057] To ensure the effectiveness of regenerative braking, the amount of electrical energy recovered by the vehicle during a long downhill descent is first calculated using the following formula: In the formula, The recovered electrical energy; h is the height difference between the start and end points of the long downhill section, in meters, which can be obtained through a high-precision map; The speed at the start of the long downhill section. The speed at the end of the long downhill section. and Take the smaller of the road speed limit and 90% of the maximum speed; The system energy recovery efficiency is the test value for each vehicle model. If no test value is available, it can be estimated as 0.65. The calculation method for the total work required for a vehicle to overcome rolling resistance and air resistance on a long downhill section is as follows: similar.

[0058] according to Determine the target SOC percentage for the long downhill section. Assuming the total energy is E when the battery SOC is 100%, the battery SOC before descending the long slope should not exceed [a certain percentage]. (Target SOC percentage for long downhill sections). If the SOC of the power battery is higher than this value before descending a long slope, the vehicle's slow braking function will fail during the descent, and the vehicle will lose its auxiliary braking capability. Therefore, the vehicle's battery control strategy needs to be temporarily adjusted to: before the vehicle reaches the starting point of the long downhill section, control its SOC to be lower than this target SOC percentage. That is, the range extender should stop working when the power battery SOC is about to reach the target SOC percentage corresponding to the long downhill section, and this value should be temporarily stored in the controller. If the vehicle is connected to an external charger at the top of the slope, charging should also be interrupted when the power battery SOC is about to reach this value (i.e., it is not necessary to wait until it reaches 100% before stopping).

[0059] S3.3: Calculate the target SOC percentage for the continuous undulating road sections following a long uphill section and a long downhill section, and perform battery control for range-extended electric vehicles.

[0060] S3.31: Determine the independent SOC constraints for each road segment: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill segment in the continuous undulating road segment.

[0061] Specifically, according to the method in step S3.1, the target percentage of SOC corresponding to each long uphill section in the continuous undulating road segment is calculated; according to the method in step S3.2, the target percentage of SOC corresponding to each long downhill section in the continuous undulating road segment is calculated.

[0062] S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion.

[0063] The reverse recursion is as follows: For each long uphill and long downhill section of a continuous undulating road segment, calculate the target SOC percentage at the starting point of each segment from the end to the beginning; after a vehicle passes through a long uphill section, its SOC is reduced by the target SOC percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the target SOC percentage corresponding to that long downhill section, and adjacent segments are connected end to end, that is, the SOC at the end of the j-th long downhill section is equal to the SOC at the starting point of the (j+1)-th long uphill section; thus, the target SOC percentage at the starting point of the continuous undulating road segment is obtained.

[0064] S3.33: Battery control for range-extended electric vehicles based on the target percentage of SOC at the starting point of a continuously undulating road section.

[0065] If the SOC target percentage at the starting point of the undulating road section is less than or equal to 100%, the vehicle's SOC will be controlled to be no lower than the SOC target percentage before reaching the starting point of the undulating road section; if its SOC is lower than the SOC target percentage at the starting point of the undulating road section, the range extender will be activated immediately to charge the vehicle.

[0066] If the SOC target percentage at the starting point of a continuously undulating road section is greater than 100%, it is determined that the energy demand of the uphill section is too high, and it is processed iteratively as follows: (1) Adjust the vehicle speed of each segment of the long uphill section in the continuous undulating road section by a preset step size (5 km / h in this embodiment), recalculate the SOC target percentage, and re-execute the reverse recursion; calculate the SOC target percentage of the starting point of the new continuous undulating road section.

[0067] (2) If it is feasible after recalculation (the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%), the battery control of the range-extended electric vehicle is carried out according to the SOC target percentage at the starting point of the new continuous undulating road segment, and at the same time, a prompt message is sent to the driver to drive at the adjusted speed.

[0068] (3) If the vehicle speed is reduced to the minimum permissible speed for that road segment and it is still not feasible, it is determined that the vehicle cannot safely pass through the current condition, and a prompt message to replan the route is issued to the driver; at the same time, the SOC target percentage at the starting point of the continuous undulating road segment calculated when the vehicle speed is reduced to the minimum permissible speed for that road segment is used as the charging target for battery control. For roads with a minimum speed limit, the minimum permissible speed is the minimum speed limit; for roads without a minimum speed limit, in this embodiment, the minimum permissible speed is 10 km / h.

[0069] When the SOC target percentage at the starting point of a continuously undulating road segment is greater than 100%, while reducing the vehicle speed, the range extender's power generation can be increased to its peak power generation to achieve faster iterative convergence and ensure that the SOC target percentage at the starting point of the continuously undulating road segment meets the requirement (less than or equal to 100%).

[0070] S4: When the self-judgment control strategy is activated, since the vehicle cannot accurately know the driver's driving intentions, it needs to make predictions based on high-precision maps. Starting from the vehicle's current position, along the current driving direction, the vehicle obtains road elevation information (for calculating gradients) within a preset prediction range (e.g., 50km) ahead using high-precision maps.

[0071] Following step S2, the system identifies long uphill sections. When it determines that a long uphill section, a long downhill section, or a continuous undulating road segment consisting of a long uphill section followed by a long downhill section, it issues a question to the driver. For example, if a long uphill section is detected, the system can ask the driver via a pop-up window on the central control screen or a voice prompt: "A long uphill section has been detected at XX ahead. Do you intend to pass through this section along the current road?" If a positive response is received or no response is received, the target SOC percentage is calculated according to step S3 based on risk control theory, and battery control for the range-extended electric vehicle is implemented. If a clear negative response is received, the vehicle is handled according to the original control mode.

[0072] If the driver inputs a destination through the in-vehicle navigation system during the execution of the self-judgment control strategy, the system will immediately switch from the self-judgment control strategy to the navigation control strategy and execute step S2.

[0073] This embodiment verifies the battery control effect of the proposed method on a continuous undulating road section consisting of a long uphill section followed by a long downhill section through the following simulation process.

[0074] The driving route is divided into three parts: a long uphill section with an average gradient of 7% and a length of 25km; a transition section with an average gradient of 0% and a length of 3km; and a long downhill section with an average gradient of 7% and a length of 10km.

[0075] The basic parameters of the vehicle are shown in Table 1.

[0076] Table 1

[0077] First calculation (initial vehicle speed 80km / h, range extender power generation 30kW): Long uphill sections in a continuous undulating road section: The work done by a vehicle to overcome the gradient resistance on a long uphill section is divided into 25 equal parts, each section being 1km long. 42875000J.

[0078] The total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section is calculated to be 12,606,500 J.

[0079] Time required to traverse the long uphill section: 0.3125 hours.

[0080] The target percentage of SOC for long uphill sections is 23.67%.

[0081] Transition sections in continuously undulating road sections: neglected.

[0082] Long downhill sections in a continuous undulating road section: The target percentage of SOC for long downhill sections is 10.32%.

[0083] The maximum SOC before descending a slope is 89.68% (if the SOC before descending a slope is greater than 89.68%, regenerative braking will fail and the vehicle will lose its auxiliary braking ability).

[0084] Reverse calculation: The SOC at the end of the long uphill section is set at 89.00% (not exceeding the upper limit of 89.68%); the SOC recovered during the downhill process is 10.32%; the SOC at the beginning of the long uphill section (the end of the transition section) is 78.68%; the SOC at the end of the long downhill section is 78.68%; the SOC consumed during the uphill process is 23.67%; the SOC at the beginning of the long downhill section (the beginning of the continuous undulating section) is 102.35%; greater than 100%, exceeding the battery's physical limit, the scheme is deemed infeasible.

[0085] The second calculation only reduced the vehicle speed (vehicle speed 75km / h, range extender power generation 30kW): SOC target percentage for long uphill sections in continuous undulating road sections: 20.37%.

[0086] Transition sections in continuously undulating road sections: neglected.

[0087] SOC target percentage for long downhill sections in undulating road sections: 10.32%.

[0088] Reverse calculation: The SOC at the end of the long uphill section is set at 89.00% (not exceeding the upper limit of 89.68%); the SOC recovered during the downhill process is 10.32%; the SOC at the beginning of the long uphill section (end of the transition section) is 78.68%; the SOC at the end of the long downhill section is 78.68%; the SOC consumed during the uphill process is 20.37%; the SOC at the beginning of the long downhill section (beginning of the continuous undulating section) is 99.05%; less than 100%, but with a margin of only 0.95%, the scheme is judged to be critically feasible.

[0089] The third calculation involved lowering the vehicle speed and adjusting the range extender's power output accordingly (vehicle speed: 75 km / h, range extender power output: 55 kW): Long uphill sections in a continuous undulating road section: The work done by a vehicle to overcome the gradient resistance on a long uphill section: 42,875,000 J (unchanged).

[0090] The total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section is calculated to be 11821250J.

[0091] Time required to traverse the long uphill section: 0.3333 hours.

[0092] The target SOC percentage for long uphill sections is 0%. During the uphill process, the battery not only does not need to discharge, but can also be charged by approximately 3.694 kWh, which is equivalent to a SOC change of -12.31%.

[0093] Transition sections in continuously undulating road sections: neglected.

[0094] Long downhill sections in a continuous undulating road section: The target percentage of SOC for long downhill sections is 10.32%.

[0095] The maximum SOC before descending a slope is 89.68% (if the SOC before descending a slope is greater than 89.68%, regenerative braking will fail and the vehicle will lose its auxiliary braking ability).

[0096] Reverse calculation: The SOC at the end of the long uphill section is set at 89.00% (not exceeding the upper limit of 89.68%); the SOC recovered during the downhill process is 10.32%; the SOC at the beginning of the long uphill section (end of the transition section) is 78.68%; the SOC at the end of the long downhill section is 78.68%; the SOC consumed during the uphill process is -12.31%; the SOC at the beginning of the long downhill section (beginning of the continuous undulating section) is 66.37%; less than 100%, the scheme is deemed feasible.

[0097] The comparison of the three calculations shows that, after adjusting the vehicle speed and the range extender's power output, this method enables vehicle control on continuous undulating road sections where a long uphill section is followed by a long downhill section, thus ensuring driving safety.

[0098] This embodiment also provides a SOC dynamic control system for a range-extended electric vehicle, the technical solution of which is as follows: including: The destination acquisition module is used to acquire the destination of the range-extended electric vehicle; when the destination is successfully acquired, the long slope determination module is called; when the destination is not acquired, the self-judgment control strategy module is called.

[0099] The long slope determination module is used to determine the driving route based on the destination and the vehicle's current location, and to identify long uphill and long downhill sections within the route, thus identifying continuous undulating road sections where a long uphill section is followed by a long downhill section. If there is a transition section between adjacent long uphill and long downhill sections, and the length of the transition section is less than a threshold, the adjacent long uphill and long downhill sections are identified as continuous undulating road sections where a long uphill section is followed by a long downhill section.

[0100] The SOC calculation and battery control module is used to calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections followed by long downhill sections based on the slope, length, and vehicle speed of the driving route; and to perform battery control of the range-extended electric vehicle based on the target SOC percentage. If the SOC target percentage at the starting point of a continuous undulating road section is less than or equal to 100%, then the vehicle's SOC shall be controlled to be no less than the SOC target percentage before reaching the starting point of the continuous undulating road section. If the SOC target percentage at the starting point of a continuous undulating road segment is greater than 100%, the vehicle speed on the long uphill section of the continuous undulating road segment will be reduced by a preset step size, and its SOC target percentage will be calculated. The reverse recursion will be performed to calculate the SOC target percentage at the starting point of the new continuous undulating road segment. This process continues until the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%, or the vehicle speed is reduced to the minimum allowable speed for the long uphill section. In step S3, the calculation process for the SOC target percentage corresponding to the continuous undulating road segment following a long uphill section and then a long downhill section is as follows: S3.31: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill section in the continuous undulating road segment; S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion; wherein, the reverse recursion is: for each long uphill and long downhill section of the continuous undulating road segment, the SOC target percentage of the starting point of each section is calculated from back to front; after a vehicle passes through a long uphill section, its SOC is reduced by the SOC target percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the SOC target percentage corresponding to that long downhill section.

[0101] The self-judgment control strategy module is used to obtain the road slope within a preset range ahead, starting from the vehicle's current position and along the current driving direction. When the long slope judgment module determines that there is a long uphill section, a long downhill section, or a continuous undulating road section where a long uphill section is followed by a long downhill section, it sends a query to the driver. If the driver gives an affirmative answer or no answer is received, the SOC target percentage is calculated based on the SOC calculation and battery control module, and the battery control of the range-extended electric vehicle is performed.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic SOC control method for a range-extended electric vehicle, characterized in that, include: S1: Obtain the destination of the range-extended electric vehicle; S2: Based on the destination and the vehicle's current location, determine the driving route, identify long uphill and long downhill sections in the driving route, and determine the continuous undulating road sections that are followed by long downhill sections after long uphill sections. If there is a transition section between adjacent long uphill and long downhill sections, and the length of the transition section is less than a threshold, the adjacent long uphill and long downhill sections are identified as continuous undulating road sections where a long uphill section is followed by a long downhill section. By relaxing the theoretical threshold, we obtain the threshold value. The formula for calculating the theoretical threshold is: in, The theoretical threshold, The SOC adjustment range for the transition phase. This refers to the total electrical energy when the power battery's SOC is 100%. V represents the power output of the battery in the transition phase of a range-extended electric vehicle when the range extender is off and the vehicle is driven in pure electric mode. S3: Based on the slope, length, and vehicle speed of the driving route, calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections where a long uphill section is followed by a long downhill section; and perform battery control for the range-extended electric vehicle based on the target SOC percentage. If the SOC target percentage at the starting point of a continuous undulating road section is less than or equal to 100%, then the vehicle's SOC shall be controlled to be no less than the SOC target percentage before reaching the starting point of the continuous undulating road section. If the SOC target percentage at the starting point of a continuous undulating road segment is greater than 100%, the vehicle speed on the long uphill section of the continuous undulating road segment will be reduced by a preset step size, and the SOC target percentage of the long uphill section will be calculated. The reverse recursion will be performed to calculate the SOC target percentage at the starting point of the new continuous undulating road segment. This process continues until the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%, or the vehicle speed is reduced to the minimum allowable speed for the long uphill section. In step S3, the calculation process for the SOC target percentage corresponding to the continuous undulating road segment following a long uphill section and then a long downhill section is as follows: S3.31: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill section in the continuous undulating road segment; S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion; wherein, the reverse recursion is: for each long uphill and long downhill section of the continuous undulating road segment, the SOC target percentage of the starting point of each section is calculated from back to front; after a vehicle passes through a long uphill section, its SOC is reduced by the SOC target percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the SOC target percentage corresponding to that long downhill section.

2. The SOC dynamic control method for a range-extended electric vehicle as described in claim 1, characterized in that, In step S2, long uphill sections and long downhill sections in the driving route are first identified. Then, based on the identified long uphill sections and long downhill sections, it is determined whether there are continuous undulating road sections where a long uphill section is followed by a long downhill section.

3. The SOC dynamic control method for a range-extended electric vehicle as described in claim 1, characterized in that, In step S2, road sections with an average slope greater than or equal to 2% and a continuous length greater than or equal to 5km that show an overall upward trend are classified as long uphill road sections; among the long uphill road sections, road sections with a slope less than 2% and a length not exceeding 2km, or road sections with a downward trend and a length not exceeding 1km, are ignored. Road sections with an average gradient of 2% or more and a continuous length of 5km or more that show a continuous downward trend are classified as long downhill road sections. In long downhill sections, sections with a gradient of less than 2% and a length of no more than 2km, or sections with an upward gradient and a length of no more than 1km, are disregarded.

4. The SOC dynamic control method for a range-extended electric vehicle as described in claim 1, characterized in that, In step S3, the calculation process for the SOC target percentage corresponding to the long uphill road section is as follows: S3.11: Calculate the work done by a vehicle overcoming gradient resistance on a long uphill section based on its gradient and length; S3.12: Calculate the total work required for a vehicle to overcome rolling resistance and air resistance on a long uphill section based on the gradient and vehicle speed. S3.13: Calculate the estimated time required for a vehicle to traverse a long uphill section based on the gradient of the uphill section and the vehicle's speed; S3.14: Based on the work done by the vehicle to overcome the gradient resistance on the long uphill section, the total work required for the vehicle to overcome rolling resistance and air resistance on the long uphill section, and the estimated time required for the vehicle to pass through the long uphill section, calculate the target percentage of SOC corresponding to the long uphill section. The battery control strategy for range-extended electric vehicles is to control the State of Charge (SOC) to be no less than the target SOC percentage before the vehicle reaches the starting point of a long uphill section.

5. The SOC dynamic control method for a range-extended electric vehicle as described in claim 4, characterized in that, The process of calculating the work done by a vehicle overcoming the gradient resistance on a long uphill section is as follows: Divide the long uphill section into equal parts by distance to obtain multiple equal segments. The number of equal parts is the rounded integer of the total length of the uphill section. Calculate the sum of the work done by the vehicle overcoming the gradient resistance in all equal segments to obtain the total work done by the vehicle overcoming the gradient resistance on the long uphill section.

6. The SOC dynamic control method for a range-extended electric vehicle as described in claim 1, characterized in that, In step S3, the target percentage of SOC corresponding to the long downhill section is calculated based on the height difference between the start and end points of the long downhill section and the vehicle speed. The battery control strategy for range-extended electric vehicles is to control the State of Charge (SOC) to be below the target SOC percentage before the vehicle reaches the starting point of a long downhill section.

7. A SOC dynamic control method for a range-extended electric vehicle as described in any one of claims 1 to 6, characterized in that, In step S1, if the destination is successfully obtained, proceed to step S2; otherwise, proceed to step S4. S4: Starting from the vehicle's current position, along the current driving direction, obtain the road slope within the preset prediction range ahead; When, based on step S2, it is determined that there is a long uphill section, a long downhill section, or a continuous undulating road section where a long uphill section is followed by a long downhill section, an inquiry is made to the driver. If the driver responds positively or not, the target SOC percentage is calculated based on step S3, and battery control of the range-extended electric vehicle is performed.

8. A SOC dynamic control system for a range-extended electric vehicle, characterized in that, A method for implementing the State of Charge (SOC) dynamic control of a range-extended electric vehicle as described in any one of claims 1 to 7 includes: The destination acquisition module is used to acquire the destination of the range-extended electric vehicle. The long slope determination module is used to determine the driving route based on the destination and the vehicle's current location, and to identify long uphill and long downhill sections in the driving route. It determines the continuous undulating road sections where a long uphill section is followed by a long downhill section. When there is a transition section between adjacent long uphill and long downhill sections, and the length of the transition section is less than a threshold, the adjacent long uphill and long downhill sections are determined to be continuous undulating road sections where a long uphill section is followed by a long downhill section. The SOC calculation and battery control module is used to calculate the target SOC percentage for long uphill sections, long downhill sections, and continuous undulating road sections followed by long downhill sections based on the slope, length, and vehicle speed of the driving route; and to perform battery control of the range-extended electric vehicle based on the target SOC percentage. If the SOC target percentage at the starting point of a continuous undulating road section is less than or equal to 100%, then the vehicle's SOC shall be controlled to be no less than the SOC target percentage before reaching the starting point of the continuous undulating road section. If the SOC target percentage at the starting point of a continuous undulating road segment is greater than 100%, the vehicle speed on the long uphill section of the continuous undulating road segment will be reduced by a preset step size, and its SOC target percentage will be calculated. The reverse recursion will be performed to calculate the SOC target percentage at the starting point of the new continuous undulating road segment. This process continues until the SOC target percentage at the starting point of the new continuous undulating road segment is less than or equal to 100%, or the vehicle speed is reduced to the minimum allowable speed for the long uphill section. The calculation process for the target SOC percentage for a continuous undulating road section following a long uphill section is as follows: S3.31: Based on the gradient, length, and vehicle speed of the driving route, calculate the target SOC percentage for each long uphill and long downhill section in the continuous undulating road segment; S3.32: Based on the SOC target percentage, the SOC target percentage of the starting point of the continuous undulating road segment is determined by reverse recursion; wherein, the reverse recursion is: for each long uphill and long downhill section of the continuous undulating road segment, the SOC target percentage of the starting point of each section is calculated from back to front; after a vehicle passes through a long uphill section, its SOC is reduced by the SOC target percentage corresponding to that long uphill section, and after passing through a long downhill section, its SOC is increased by the SOC target percentage corresponding to that long downhill section.

9. The SOC dynamic control system for a range-extended electric vehicle as described in claim 8, characterized in that, It also includes a self-judgment control strategy module, which is used to obtain the road slope within a preset range ahead, starting from the current position of the vehicle and along the current driving direction; when the long slope judgment module determines that there is a long uphill section, a long downhill section, or a continuous undulating road section where a long uphill section is followed by a long downhill section, it will ask the driver a question. If the driver responds positively or not, the target SOC percentage is calculated based on the SOC calculation and battery control module, and battery control of the range-extended electric vehicle is performed. The destination acquisition module is also used to invoke the self-judgment control strategy module when destination acquisition fails.

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