A super capacitor charging method for a hybrid energy storage system of an electric vehicle

Abstract

The application discloses a super capacitor charging method of an electric vehicle hybrid energy storage system, wherein the upper limit SOC of the super capacitor is determined according to the energy consumption distribution of the next section; at an intersection, the charging power of the intersection is determined according to the upper limit SOC, the current SOC and the waiting time, and the super capacitor is charged to the upper limit SOC; the minimum SOC of the super capacitor is determined according to the maximum output power of the lithium battery and the waiting time of the next intersection; the SOC of the super capacitor after acceleration is determined according to the acceleration energy consumption, and the greater one of the minimum SOC and the SOC after acceleration is taken as the lower limit SOC of the super capacitor; during the driving on a section, the output power of the lithium battery is adjusted based on the difference between the current SOC of the super capacitor and the lower limit SOC, and the lithium battery charges the super capacitor with the part of the output power greater than the driving power. The application can reduce the cost and weight of the hybrid energy storage system, effectively save the lithium battery power and improve the overall efficiency of the system.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicle technology, specifically relating to a supercapacitor charging method for a hybrid energy storage system for electric vehicles. Background Technology

[0002] As one of the core technologies of electric vehicles, batteries face increasingly higher demands due to the rapid development of electric vehicles. Currently, energy-type batteries, such as lithium iron phosphate batteries and ternary lithium batteries, hold the largest market share among power batteries, boasting advantages such as high energy density, high energy conversion efficiency, and low self-discharge rate. While energy-type batteries meet the high energy density requirements of electric vehicles for energy storage systems, high power density is necessary when electric vehicles frequently encounter situations requiring high-power discharge, such as acceleration, hill climbing, and emergency stopping. Hybrid energy storage systems composed of high-power-density power-type batteries and energy-type batteries can effectively meet the comprehensive requirements of electric vehicles for both energy density and power density. However, current mature power-type batteries, such as supercapacitors, are costly and heavy, while other types of power-type batteries, such as lithium-ion capacitors and hybrid electrode batteries, are not yet mature in the market and are costly. Furthermore, previous research often did not consider limiting the capacity parameters of power batteries in order to meet energy distribution strategies. These two aspects have hindered the practical application of hybrid energy storage systems in electric vehicles.

[0003] To reduce the overall cost and weight of hybrid energy storage systems while meeting the energy consumption requirements of supercapacitors in the energy distribution strategy, it is necessary to consider timely replenishment of the lower-energy-density supercapacitors. Currently, supercapacitors in hybrid energy storage systems are primarily charged by recovering braking energy during the deceleration of electric vehicles, but this method of replenishment is insufficient to meet the energy demands of supercapacitors. When the supercapacitor's charge is insufficient to meet the peak power requirements of the energy distribution strategy, the hybrid energy storage system will fail. Therefore, it is necessary to charge the supercapacitors while the electric vehicle's motor drive power is low, simultaneously outputting the power required by the motor. However, this method makes it difficult to determine the appropriate charging timing and charging power, reducing the overall energy utilization rate of the system. Summary of the Invention

[0004] This invention provides a supercapacitor charging method for a hybrid energy storage system for electric vehicles. On the one hand, it obtains the upper limit SOC value for charging, which can provide a reference standard for matching the capacity parameters of the supercapacitor, thus helping to reduce the overall cost and weight of the hybrid energy storage system. On the other hand, it obtains the lower limit SOC value for charging, enabling the matching of the supercapacitor's on-road charging strategy with actual driving conditions, effectively saving lithium-ion battery power and improving the overall system efficiency.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A power battery charging method for an electric vehicle hybrid energy storage system includes:

[0007] Based on the pre-allocated energy consumption of the supercapacitor in the next road segment, the upper limit of the supercapacitor's state of charge (SOC) is determined. Then, based on the upper limit of the SOC, the actual SOC at the intersection, and the waiting time at the intersection, the supercapacitor charging power P during the intersection waiting process is determined. I_LIB The intersection refers to the intersection between the current road segment and the next road segment.

[0008] The minimum SOC of the supercapacitor is determined based on the maximum output power of the lithium-ion battery and the expected waiting time at the next intersection. Then, based on the acceleration energy consumption of the electric vehicle driven by the driver from a standstill to the speed of the next road segment and the required SOC of the supercapacitor, the SOC of the supercapacitor after acceleration is determined, and the larger of the SOC of the supercapacitor and the minimum SOC of the supercapacitor is taken as the lower limit SOC of the supercapacitor.

[0009] During the stopping and waiting process at the intersection, the lithium-ion battery charges at a power P. I_LIB The supercapacitor is charged to the upper limit SOC. When the electric vehicle is driving in the next segment and the current SOC of the supercapacitor is lower than the lower limit SOC, the lithium-ion battery further adjusts the output power according to the difference between the current SOC of the supercapacitor and the lower limit SOC. When the driving power of the electric vehicle is low, that is, lower than the preset value, the lithium-ion battery charges the supercapacitor with the part of the output power that is greater than the driving power of the motor.

[0010] Furthermore, the method for determining the upper limit of the state of charge (SOC) of a supercapacitor is as follows:

[0011] The upper limit voltage U of a supercapacitor after charging is calculated based on the following formula for the charge capacity of a supercapacitor. SC_up :

[0012]

[0013] In the formula, E SC U represents the pre-allocated energy consumption of the supercapacitor based on predicted energy consumption, where C is the capacitance of the supercapacitor, and U is the energy consumption of the supercapacitor. SC_co This is the cutoff voltage of the supercapacitor;

[0014] Then, based on the linear relationship between the SOC and voltage of the supercapacitor, the upper limit of the supercapacitor's charging SOC is obtained. SC_up .

[0015] Furthermore, the calculation method for the supercapacitor charging power during the stopping and waiting process at an intersection is as follows:

[0016] First, calculate the waiting time t of the electric vehicle at the intersection. I :

[0017] t I =t R +t L

[0018] In the formula, t R and t L These represent the remaining red light time at the intersection and the queuing delay time for electric vehicles in the approach lanes, respectively.

[0019] Then, based on the current SOC of the supercapacitor after the electric vehicle stops at the intersection, and the SOC... SC_up The difference ΔSOC SC_I and charging time t I Determine the charging power P of the lithium-ion battery to the supercapacitor. I_LIB =f(ΔSOC) SC_I ,t I ).

[0020] Furthermore, the method for determining the minimum SOC of a supercapacitor is as follows:

[0021] First, calculate the maximum charge E that the lithium-ion battery can provide to the supercapacitor at the next intersection. SC_max :

[0022] E SC_max =P LIB_max ·t IP

[0023] In the formula, t IP P represents the estimated waiting time at the next intersection. LIB_max This represents the maximum output power of the lithium-ion battery.

[0024] Then, based on the supercapacitor requirements, it is charged to SOC at the next intersection. SC_up That is, charging to the corresponding upper limit voltage U SC_up And the maximum charge capacity E based on lithium-ion batteries SC_max Determine the minimum charging voltage U of the supercapacitor. SC_CL :

[0025]

[0026] In the formula, C represents the capacitance of the supercapacitor;

[0027] Based on the linear relationship between the SOC and voltage of a supercapacitor, the minimum charging voltage U of the supercapacitor is... SC_CL Obtain its minimum SOC value for charging, i.e., SOC SC_CL .

[0028] Furthermore, the method for determining the supercapacitor's state of charge (SOC) required for initial acceleration is as follows:

[0029] First, a starting acceleration curve based on driver habits is fitted using historical data. Then, the energy consumption from a standstill to the average vehicle speed on the road segment is calculated based on this starting acceleration curve, which is the required supercapacitor charge E. SC_acc ;

[0030] Then, based on the cutoff voltage U of the supercapacitor SC_co Calculate the supercapacitor voltage U corresponding to this energy consumption. SC_acc :

[0031]

[0032] Finally, based on the linear relationship between the SOC and voltage of the supercapacitor, the supercapacitor voltage U... SC_acc The corresponding SOC value is obtained, which is the supercapacitor SOC required for starting acceleration (accelerating from a standstill to the average speed of the vehicle on the road segment).

[0033] Furthermore, the lower limit of the supercapacitor's state of charge (SOC) is further adjusted based on the driver's driving style. SC_low Configure the settings, specifically:

[0034] Note the supercapacitor SOC required for initial acceleration relative to SOC SC_co The difference is ΔSOC acc SOC SC_co This is the cutoff SOC of the supercapacitor;

[0035] Set ΔSOC2 according to the following formula:

[0036]

[0037] In the formula, λ is the driving style coefficient, which is obtained by classifying and quantifying driving style characteristic parameters from the driver's historical driving data; the more aggressive the driving style, the larger the value of λ; the more cautious the driving style, the closer the value of λ is to 1; U SC_up Here, μ represents the upper limit voltage for charging the supercapacitor, and μ is the road condition coefficient.

[0038] The lower limit of the state of charge (SOC) of the supercapacitor charged in the road is then set as SOC. SC_low :

[0039] SOC SC_low =max(SOC) SC_CL SOC SC_co +ΔSOC2).

[0040] Furthermore, the road condition coefficient μ, and the average travel delay d within the road segment traveled by the electric vehicle.s and average driving time t D To determine:

[0041]

[0042] Furthermore, the adjustment of the lithium-ion battery's output power during driving on the road section specifically involves:

[0043] When the current SOC of the supercapacitor is lower than the charging lower limit SOC while the electric vehicle is driving on the road SC_low Increase the output power P of lithium-ion batteries LIB :

[0044] P LIB = (1+α)·P LIB_HESS

[0045] In the formula, P LIB_HESS The lithium-ion battery output power is determined by the energy distribution strategy of the hybrid energy storage system, where α is the lithium-ion battery output power adjustment coefficient.

[0046] And the electric vehicle's driving power P D Less than the output power P allocated to the lithium-ion battery LIB At that time, the lithium-ion battery will maintain this output power P. LIB ;

[0047] When the current SOC of the supercapacitor reaches SOC SC_low At that time, control the output power P of the lithium-ion battery LIB The power level decreases gradually to the low value P of the motor drive power. D_low If in P LIB During the descent, the electric vehicle accelerates, increasing the driving power P. D Rapid rise, then control the output power P of the lithium-ion battery LIB Follow drive power P D The upward curve increases;

[0048] The lithium-ion battery charges the supercapacitor while simultaneously outputting driving power; that is, the supercapacitor's charging power P SC_C for:

[0049] P SC_C =P LIB -P D .

[0050] Furthermore, the lithium-ion battery output power adjustment coefficient α is obtained based on the difference between the current SOC of the supercapacitor and its lower charging limit SOC:

[0051]

[0052] In the formula, SOCSC The current SOC of the supercapacitor. SC_co This is the cutoff SOC of the supercapacitor.

[0053] Beneficial effects

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] (1) The upper limit of the supercapacitor's SOC value is determined based on the predicted energy consumption of the next road segment to be entered. This effectively utilizes the parking time of electric vehicles at intersections when driving on urban roads to allow the supercapacitor to recover its power. This ensures that the supercapacitor has sufficient power to meet the energy distribution strategy of the hybrid energy storage system when the electric vehicle is driving on the next road segment. It can provide a reference standard for matching the capacity parameters of the supercapacitor, which is conducive to reducing the overall cost and weight of the hybrid energy storage system.

[0056] (2) On-road charging flexibly adjusts the lower limit of the supercapacitor's State of Charge (SOC) value based on driver style, the energy distribution strategy of the hybrid energy storage system, and the traffic conditions of the next road segment. This achieves precise matching between the supercapacitor's on-road charging strategy and actual driving conditions, ensuring that the supercapacitor's stored energy meets the minimum requirements of the energy distribution strategy. This effectively saves lithium-ion battery power and improves the overall system efficiency. Simultaneously, the charging method reduces the rate of change in lithium-ion battery output power, which helps extend the lifespan of the lithium-ion battery and maintain the consistency of the power battery pack's state. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of an embodiment of the supercapacitor charging method for the electric vehicle hybrid energy storage system described in this specification.

[0058] Figure 2 This is a schematic diagram of an embodiment of the SOC values ​​and related parameters of the supercapacitor described in this specification.

[0059] Figure 3 This is a schematic diagram of an embodiment of the charging curve of a lithium-ion battery to a supercapacitor described in this specification. Detailed Implementation

[0060] The embodiments of the present invention will be described in detail below. These embodiments are based on the technical solutions of the present invention and provide detailed implementation methods and specific operation processes to further explain the technical solutions of the present invention.

[0061] like Figure 1The diagram illustrates one embodiment of the supercapacitor charging method for the electric vehicle hybrid energy storage system. It shows different charging locations for the supercapacitor in the system: an intersection and the road between intersections. Based on these two charging locations, the supercapacitor charging method for the electric vehicle hybrid energy storage system is divided into two types: intersection charging and roadside charging.

[0062] (1) Cross-port charging

[0063] Cross-traffic charging utilizes the time while the electric vehicle is waiting at a red light to charge the supercapacitor to its maximum SOC (State of Charge), ensuring the supercapacitor's charge is sufficient to meet the basic requirements of the hybrid energy storage system's energy distribution strategy for the electric vehicle's journey on the next road segment. After pre-allocating the predicted energy consumption for the next road segment using the hybrid energy storage system's energy distribution strategy, the required energy E from the supercapacitor during the electric vehicle's journey on that next road segment is obtained. SC Based on the formula for the charge capacity of a supercapacitor, the upper limit voltage U of the supercapacitor after charging can be calculated. SC_up :

[0064]

[0065] In this formula, C represents the capacitance of the supercapacitor, and U... SC_co This is the cutoff voltage of the supercapacitor. Since the state of charge (SOC) of a supercapacitor has a simple linear relationship with its voltage, it can be determined by the upper charging limit voltage U of the supercapacitor. SC_up and cutoff voltage U SC_co The upper limit of the supercapacitor's charge state (SOC) is obtained. SC_up ) and cutoff SOC (SOC) SC_co ),like Figure 2 As shown.

[0066] Among them, such as Figure 1 As shown, the time spent waiting at a red light at an intersection includes two parts: the remaining red light time t. R And the queuing delay time t of electric vehicles in the approach lane L Therefore, the charging time t at the intersection is... I The following formula can be used for calculation:

[0067] t I =t R +t L

[0068] Finally, when the electric vehicle arrives at the intersection and waits for the red light, the SOC of the supercapacitor after the electric vehicle stops at the intersection is calculated. SC_up The difference ΔSOC SC_I and charging time t IThe lithium-ion battery charges the supercapacitor at a constant power (P). I_LIB =f(ΔSOC) SC_I ,t I The charging power can be optimized based on the output power of the lithium-ion battery before the electric vehicle is parked, in order to reduce fluctuations in the output power of the lithium-ion battery.

[0069] (2) Charging on the road

[0070] In-the-road charging addresses situations where the actual energy consumption of an electric vehicle (EV) exceeds its predicted energy consumption as it travels on the next road segment. The hybrid energy storage system needs to determine the minimum State of Charge (SOC) value of the supercapacitor. This ensures that the supercapacitor's charge level meets the minimum requirements of the hybrid energy storage system's energy distribution strategy while the EV is traveling on the road, and prevents the supercapacitor from being unable to reach its SOC at the next intersection due to insufficient charge. SC_up .

[0071] like Figure 1 As shown, to ensure that electric vehicles can be charged to SOC at the next intersection SC_up The maximum output power P of the lithium-ion battery is determined based on the capacity allocation strategy of the hybrid energy storage system. LIB_max And the estimated red light time t when reaching the next intersection IP Calculate the maximum charge E that the lithium-ion battery can provide to the supercapacitor at the next intersection. SC_max :

[0072] E SC_max =P LIB_max ·t IP

[0073] To ensure that the battery can be charged to SOC at the next intersection SC_up Based on this maximum charging capacity, the minimum charging voltage U of the supercapacitor is determined. SC_CL :

[0074]

[0075] The minimum charging voltage U SC_CL The corresponding SOC is the minimum SOC value for charging the supercapacitor (SOC). SC_CL ), which is related to SOC SC_up The difference ΔSOC1 reflects the maximum charging capacity of the lithium-ion battery for the supercapacitor at the intersection, such as... Figure 2 As shown.

[0076] During actual driving, the driver's driving style and road conditions significantly impact the actual energy consumption of electric vehicles. Therefore, the supercapacitor needs to maintain a certain level of charge to meet the minimum requirements of the hybrid energy storage system's energy distribution strategy. For the supercapacitor in the hybrid energy storage system, its energy consumption is primarily used for the acceleration of the electric vehicle. By fitting the driver's habitual acceleration curve from historical data, the amount of supercapacitor charge E consumed by the driver from initial acceleration to the average speed of the vehicle on the road segment is calculated. SC_acc Then based on the cutoff voltage U SC_co Calculate the supercapacitor voltage U corresponding to this energy consumption. SC_acc :

[0077]

[0078] The voltage U SC_acc The corresponding supercapacitor SOC and SOC SC_co The difference ΔSOC acc This refers to the maximum SOC consumption of the supercapacitor during a single acceleration of an electric vehicle on this road.

[0079] Considering the driver's driving style, a more aggressive driving style results in more acceleration of the electric vehicle while driving on the road, leading to a faster drop in the supercapacitor's State of Charge (SOC). Therefore, the supercapacitor should retain more charge to meet the driver's needs. Conversely, a cautious driving style requires at least a certain amount of charge to maintain. SC_acc The corresponding SOC value of the supercapacitor.

[0080] Meanwhile, in actual road driving of electric vehicles, the greater the driving delay, the more points of stopping or significant deceleration there are. This means that the hybrid energy storage system of the electric vehicle has more opportunities for the lithium-ion battery to charge the supercapacitor, and the required charge level of the supercapacitor can be appropriately reduced.

[0081] Based on the above analysis Figure 2 ΔSOC2 can be calculated using the following formula:

[0082]

[0083] In the above formula, λ is the driving style coefficient. It can be used to classify and quantify driving style characteristic parameters in the driver's historical driving data using statistical models, such as acceleration frequency, average acceleration, and accelerator pedal depth while driving on the road. The more aggressive the driving style, the larger the value of λ, but it cannot exceed the supercapacitor's maximum state of charge (SOC); the more cautious the driving style, the closer the value of λ is to 1.

[0084] μ is the road condition coefficient, which can be obtained from the average travel delay d within the road segment traveled by the electric vehicle. s and average driving time tD To determine:

[0085]

[0086] Meanwhile, to ensure that electric vehicles can be charged to SOC at the next intersection SC_up The lower limit of supercapacitor charging SOC (SOC) determined during road charging is... SC_low )for:

[0087] SOC SC_low =max(SOC) SC_CL SOC SC_co +ΔSOC2)

[0088] It should be noted that when the light is expected to be green at the next intersection, the SOC... SC_low =SOC SC_up .

[0089] like Figure 3 As shown, the SOC (State of Charge) of the supercapacitor during the driving of an electric vehicle on the road is... SC (Below SOC) SC_low Subsequently, it is necessary to increase the output power P of the lithium-ion battery. LIB :

[0090] P LIB = (1+α)·P LIB_HESS

[0091] In the formula, P LIB_HESS The output power of the lithium-ion battery is determined by the original energy distribution strategy of the hybrid energy storage system, and α is the lithium-ion battery output power adjustment coefficient; α is based on the current SOC of the supercapacitor (SOC). SC The difference between it and its lower charging limit SOC is obtained:

[0092]

[0093] Electric vehicle drive power P D The lithium-ion battery output power P is less than that determined by the current energy distribution strategy of hybrid energy storage systems. LIB At this time, the lithium-ion battery will maintain this output power, charging the supercapacitor while outputting drive power. The supercapacitor charging power at this time is:

[0094] P SC_C =P LIB -P D

[0095] It should be noted that if the driving power is converted into regenerative braking power (P... D If <0), the above formula still holds, and the lithium-ion battery still maintains P. LIBCharge the supercapacitor.

[0096] When SOC SC Achieving SOC SC_low At that time, P LIB It will decrease along a relatively gentle curve, if at P LIB During the descent, the electric vehicle accelerates, causing P D Rapid rise, P LIB Follow P D The curve increases.

[0097] The above embodiments are preferred embodiments of this application. Those skilled in the art can make various changes or improvements based on them. Without departing from the overall concept of this application, these changes or improvements should fall within the scope of protection claimed in this application.

Claims

1. A supercapacitor charging method for a hybrid energy storage system for electric vehicles, characterized in that, include: The upper limit of the supercapacitor's state of charge (SOC) is determined based on the pre-allocated energy consumption of the supercapacitor in the next segment. Then, based on the upper limit of SOC, the actual SOC when stopped at the intersection, and the waiting time at the intersection, the supercapacitor charging power during the intersection waiting process is determined. The intersection refers to the intersection between the current road segment and the next road segment. The minimum SOC of the supercapacitor is determined based on the maximum output power of the lithium-ion battery and the expected waiting time at the next intersection. Then, based on the acceleration energy consumption of the electric vehicle driven by the driver from a standstill to the speed of the next road segment and the required supercapacitor SOC, the supercapacitor SOC after acceleration is determined, and the larger of the supercapacitor SOC and the minimum SOC of the supercapacitor is taken as the lower limit SOC of the supercapacitor. During the stopping and waiting process at the intersection, the lithium-ion battery operates at a charging power. The supercapacitor is charged to the upper limit SOC. When the electric vehicle is driving in the next segment and the current SOC of the supercapacitor is lower than the lower limit SOC, the lithium-ion battery further adjusts the output power according to the difference between the current SOC of the supercapacitor and the lower limit SOC. When the driving power of the electric vehicle is lower than the preset value, the lithium-ion battery charges the supercapacitor with the part of the output power that is greater than the driving power of the motor.

2. The method according to claim 1, characterized in that, The method for determining the upper limit of the state of charge (SOC) of a supercapacitor is as follows: The upper limit voltage of a supercapacitor after charging is calculated based on the following formula for the charge capacity of a supercapacitor. : ； In the formula, This refers to the pre-allocated energy consumption of supercapacitors based on predicted energy consumption. This refers to the capacitance of the supercapacitor. This is the cutoff voltage of the supercapacitor; Then, based on the linear relationship between the SOC and voltage of the supercapacitor, the upper limit of supercapacitor charging is obtained. .

3. The method according to claim 1, characterized in that, The calculation method for supercapacitor charging power during the parking and waiting process at an intersection is as follows: First, calculate the parking waiting time of the electric vehicle at the intersection. : ； In the formula, and These represent the remaining red light time at the intersection and the queuing delay time for electric vehicles in the approach lanes, respectively. Then, based on the current SOC of the supercapacitor after the electric vehicle stops at the intersection and difference and charging time The charging power of the lithium-ion battery to the supercapacitor was determined.

4. The method according to claim 1, characterized in that, The method for determining the minimum SOC of a supercapacitor during charging is as follows: First, calculate the maximum amount of electricity that the lithium-ion battery can charge the supercapacitor at the next intersection. : ； In the formula, The estimated waiting time at the next intersection. This represents the maximum output power of the lithium-ion battery. Then, based on the supercapacitor requirement, it will be charged at the next intersection. That is, charging to the corresponding upper limit voltage. and the maximum charge capacity based on lithium-ion batteries Determine the minimum charging voltage of the supercapacitor. : ； In the formula, This refers to the capacitance of the supercapacitor. Based on the linear relationship between the state of charge (SOC) and voltage of a supercapacitor, the minimum charging voltage of the supercapacitor is... To obtain its minimum SOC value for charging, i.e. .

5. The method according to claim 1, characterized in that, The method for determining the SOC (State of Charge) of the supercapacitor required for initial acceleration is as follows: First, a starting acceleration curve based on driver habits is fitted using historical data. Then, the energy consumption from a standstill to the average vehicle speed on the road segment is calculated based on this starting acceleration curve, which is the amount of supercapacitor power required. ; Then, based on the cutoff voltage of the supercapacitor Calculate the supercapacitor voltage corresponding to this energy consumption. : ； Finally, based on the linear relationship between the SOC and voltage of the supercapacitor, the voltage of the supercapacitor is... The corresponding SOC value is obtained, which is the supercapacitor SOC required for start-up acceleration.

6. The method according to claim 5, characterized in that, Further adjust the lower limit of supercapacitor charging based on the driver's driving style. Configure the settings, specifically: The supercapacitor SOC required for initial acceleration relative to The difference is , This is the cutoff SOC of the supercapacitor; Will Set it according to the following formula: ； In the formula, The driving style coefficient is obtained by classifying and quantifying driving style characteristic parameters from the driver's historical driving data; the more aggressive the driving style, the higher the coefficient. The higher the value, the more cautious the driving style. The closer the value is to 1; This refers to the upper limit voltage for charging supercapacitors. This refers to the road condition coefficient; The lower limit of state of charge (SOC) for a supercapacitor charged in the road is then set as follows: : 。 7. The method according to claim 6, characterized in that, Road condition coefficient Average travel delay within the road segment traveled by electric vehicles and average driving time To determine: 。 8. The method according to claim 1, characterized in that, The specific steps for adjusting the output power of a lithium-ion battery are as follows: When the current SOC of the supercapacitor is lower than the charging threshold while the electric vehicle is driving on the road... Then, increase the output power of lithium-ion batteries. : ； in the formula The lithium-ion battery output power determined for the energy distribution strategy of the hybrid energy storage system. This refers to the output power adjustment coefficient for lithium-ion batteries. And electric vehicle drive power Less than the output power of lithium-ion batteries At that time, the lithium-ion battery will maintain this output power. ; When the current SOC of the supercapacitor reaches At the same time, control the output power of the lithium-ion battery. The power gradually decreases to a low value in the motor drive power curve. If in During descent, the electric vehicle accelerates, increasing the driving power. Rapid rise, then control the output power of the lithium-ion battery. Follow drive power The upward curve increases; The lithium-ion battery charges the supercapacitor while simultaneously outputting driving power; that is, the charging power of the supercapacitor. for: 。 9. The method according to claim 8, characterized in that, Lithium-ion battery output power adjustment coefficient The value is obtained based on the difference between the current SOC of the supercapacitor and its lower charging limit SOC: ； In the formula, SOC SC This represents the current state of charge (SOC) of the supercapacitor. This is the cutoff SOC of the supercapacitor.

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