Direct-drive electricity supplementing method for power dividing framework of hybrid electric vehicle

Abstract

The invention relates to the field of vehicle control, in particular to a direct-drive electricity supplementing method for a hybrid electric vehicle power dividing framework, which comprises the following steps of: obtaining a curve relation between a vehicle speed and a maximum driving torque of a wheel end; acquiring a wheel end demand driving torque; acquiring the maximum driving torque of the wheel end, dispersing the maximum driving torque into a plurality of parts, acquiring discrete data greater than the required driving torque of the wheel end, and forming a to-be-selected point set; after a to-be-selected point is selected, the driving consumption power is calculated based on the to-be-selected point, the optimal power of the engine is dispersed into a plurality of parts, a battery storage power number set and a corresponding engine combustion power number set are obtained, a plurality of charging efficiencies are obtained, and the maximum value is found to serve as the good charging efficiency; and by analogy, calculating good charging efficiency corresponding to other to-be-selected points, and comparing to find out the maximum value as the optimal charging efficiency at the current vehicle speed. According to the direct-drive electricity supplementing method for the power dividing framework of the hybrid electric vehicle, the overall efficiency of the engine and the motor in the electricity supplementing process in the direct-drive mode is optimal, and energy is saved.

Description

Technical Field

[0001] This invention relates to the field of vehicle control, and more specifically to a direct-drive power replenishment method for a hybrid vehicle power split architecture. Background Technology

[0002] Currently, the direct drive mode of hybrid electric vehicles refers to a working mode in which, when the vehicle is traveling at high speeds (such as above 100 km / h), the engine is directly connected to the drive shaft via a clutch or dedicated transmission, bypassing intermediate components such as the electric motor and generator, and directly driving the wheels. The core purpose of the direct drive mode is to improve fuel economy and power transmission efficiency at high speeds, while reducing energy conversion losses.

[0003] The principle of how hybrid electric vehicles replenish the power battery in direct drive mode is that, in a power-split architecture, the generator is locked by a locking mechanism when the hybrid electric vehicle is driving at high speed, thus achieving engine direct drive mode. And when the engine is directly driving the wheels, the excess power is used to replenish the power battery through the drive motor.

[0004] In related technologies, Chinese patent CN115891968A discloses a direct-drive charging control method, device, equipment, and medium for hybrid vehicles. This method involves determining whether to activate the drive motor to charge the battery after the vehicle enters engine direct drive mode, based on the battery's charge level. It then determines the target power output of the drive motor and the target output power of the engine for battery charging based on the engine's maximum output power, the drive motor's maximum power output, and the engine power required for normal vehicle operation. Finally, it determines the drive motor's output torque based on the target power output and the engine's output torque based on the target output power. This patent enables timely battery charging when the battery is low after the vehicle enters engine direct drive mode, ensuring the power needs of all electric components and thus guaranteeing safe vehicle operation.

[0005] However, the main purpose of the above-mentioned patent solution is to coordinate the various assemblies to maintain the normal operation of the vehicle. Based on the maximum output power of the engine, the maximum power generation of the drive motor, and the engine power required to maintain the normal operation of the vehicle, the target power generation of the drive motor and the target output power of the engine are determined when the battery power is low and the battery is being charged. In this process, the engine may be forced to deviate from its optimal efficiency point, or the efficiency of the motor may decrease, resulting in a decrease in the overall efficiency of the engine and motor system.

[0006] Therefore, those skilled in the art urgently need to design a technical solution to achieve optimal overall efficiency of the engine and motor during the charging process in the direct drive mode of a hybrid vehicle power split architecture. Summary of the Invention

[0007] This application provides a direct-drive power-splitting method for hybrid vehicles, which optimizes the overall efficiency of the engine and motor during the power-splitting process in direct-drive mode, thereby saving energy.

[0008] This application provides a direct-drive power replenishment method for a hybrid vehicle power split architecture, comprising the following steps: Several vehicle speeds were selected within the speed range of the hybrid vehicle to obtain the curve relationship between vehicle speed and maximum driving torque at the wheel end. The required driving torque at the wheel end is obtained based on the current vehicle status; the maximum driving torque at the wheel end at the current vehicle speed is obtained and discretized into several parts, all of which are compared with the required driving torque at the wheel end to obtain discrete data that are greater than the required driving torque at the wheel end, forming a set of candidate points; After selecting a candidate point from the candidate point set, the drive power consumption is calculated based on the candidate point. The optimal engine power is discretized into several parts to obtain the battery power storage set and the corresponding engine combustion power set. The sum of the drive power consumption and the battery power storage set is divided by the engine combustion power set to obtain multiple charging efficiencies. The maximum value is found as the good charging efficiency. Similarly, calculate the good charging efficiency corresponding to the remaining candidate points, compare the good charging efficiency corresponding to all candidate points, and find the maximum value as the optimal charging efficiency at the current vehicle speed.

[0009] In one embodiment, selecting several vehicle speeds within the speed range of the hybrid vehicle to obtain a curve relationship between the vehicle speed and the maximum driving torque at the wheel end includes: Within the speed range of hybrid vehicles, select several vehicle speeds and calculate the set of drive motor speeds. Based on the set of drive motor speeds, the set of peak torques of the drive motors is obtained by Lagrange polynomial interpolation. Based on the peak torque set of the drive motor, and considering that the peak torque of the engine is coupled with the peak torque of the drive motor at the output shaft of the hybrid powertrain after being output through the planetary gear set, the maximum drive torque set at the wheel end is calculated, and the curve relationship between vehicle speed and maximum drive torque at the wheel end is obtained.

[0010] In one implementation, several vehicle speeds are selected within the speed range of the hybrid vehicle, and a set of drive motor speeds is calculated, including: Based on the formula MGS = v / 3.6 / WR×60 / π / 2×FR×GR, substituting the selected n vehicle speeds into this formula yields a dataset of n MGS values. ; Where MGS represents the drive motor speed in rpm; v represents the vehicle speed in km / h; GR represents the AMT speed ratio in the power split architecture; FR represents the main reducer speed ratio in the power split architecture; and WR represents the tire rolling radius.

[0011] In one implementation, the peak torque set of the drive motor is obtained by Lagrange polynomial interpolation based on the set of drive motor speeds, including: Construct the Lagrange interpolation basis function related to the speed of the drive motor. : ; Calculate the peak torque of the drive motor ; ; Will Substituting each number into the given data, we obtain the set of peak torque values ​​for the drive motor. ; in, Motor external characteristic speed sequence, in rpm; Motor external characteristic torque sequence, unit Nm; during calculation correspond And so on. correspond .

[0012] In one implementation, the set of maximum drive torques at the wheel ends is calculated based on the set of peak torques of the drive motor, including: Based on the relationship between the maximum driving torque Ft at the wheel end and the peak torque MGTM of the drive motor; Ft=(ETM×K / (K+1)×0.98+MGTM×GR×GE)×FR×FE / WR; Set the peak torque data of the drive motor Substitute each number into the set of maximum drive torque values ​​at the wheel end to obtain the set of values. ; Where Ft is in Nm; ETM represents the engine peak torque in Nm; K represents the planetary gear set characteristic parameters; GE represents the AMT mechanical efficiency; and FE represents the final drive efficiency.

[0013] In one implementation, the required wheel-end drive torque is obtained based on the current vehicle state; the maximum wheel-end drive torque at the current vehicle speed is obtained and discretized into several parts, all of which are compared with the required wheel-end drive torque to obtain discrete data greater than the required wheel-end drive torque, forming a set of candidate points, including: Based on the wheel-end demand drive torque calculation module in the VCU, the current wheel-end demand drive torque Ftx is obtained according to the current vehicle speed, pedal opening, and NRD gear status. Based on the current vehicle speed, and using the curve relationship between vehicle speed and maximum wheel-end driving torque, obtain the maximum wheel-end driving torque Ft0 at the current vehicle speed; Discretize the maximum driving torque at the wheel end at the current vehicle speed. Discretize the maximum driving torque at the wheel end at the current vehicle speed at equal intervals of m parts from 1 Nm to m discrete maximum driving torque at the wheel end, which are 1, Ft0 / m, 2Ft0 / m·····h×Ft0 / m······1×Ft0; where 1 < h < m. When hFt0 / m<Ftx<(h+1)×Ft0 / m, the set of points to be selected is FtR={(h+1)×Ft0 / m、(h+2)×Ft0 / m、……、1×Ft0}.

[0014] In one implementation, a candidate point is selected, the drive power consumption is calculated, the optimal engine power is discretized into several parts, a set of battery stored power and a corresponding set of engine combustion power are obtained, multiple charging efficiencies are obtained, and the maximum value is found as a good charging efficiency, including: From the set of candidate points, select one candidate point FtR1; The engine power discrete set is obtained by discretizing the engine starting power of 40 kW and the engine optimal power by m parts; based on the engine power discrete set, the engine speed set is obtained by Lagrange polynomial interpolation, and then the engine torque set is calculated. Based on FtR1, the actual torque at the wheel end is calculated, and combined with the engine torque set, the actual torque set of the drive motor is calculated, thereby obtaining the drive motor power set. The driving power consumption is obtained based on FtR1 and the current vehicle speed. The battery storage power is obtained based on the drive motor power set. The engine combustion power is obtained based on the engine speed set and engine torque set. Multiple charging efficiencies are then calculated, and the maximum value is found as the good charging efficiency.

[0015] In one implementation, the engine power discretization is performed m times between the engine start-up power of 40 kW and the engine's optimal power to obtain a discrete set of engine power. Based on this discrete set, the engine speed set is obtained through Lagrange polynomial interpolation, and then the engine torque set is calculated, including: The engine starting power of 40 kW is discretized into m parts from the engine's optimal power to obtain the engine power discrete set EPR; EPR=[40, 40+(EZPM-40) / m, 40+2×(EZPM-40) / m, ······, 40+1×(EZPM-40)]; Where EZPM represents the engine's peak optimal power, in kW; Based on the discrete set EPR of the engine's optimal power, the engine speed set is obtained through Lagrange polynomial interpolation, and the engine torque set is calculated, including: Constructing Lagrange interpolation basis functions ; ; Calculate engine speed ; ; ES indicates engine speed, measured in rpm; Substituting each number in the discrete set of engine power EPR, we obtain the set of engine speeds. ;in, : The original optimal power sequence of the engine; : The original optimal speed sequence of the engine; Based on the engine speed data set, the engine torque data set is obtained according to the formula ET=9549×EPR / ES. .

[0016] In one implementation, based on FtR1, the actual wheel-end torque is calculated, and combined with the engine torque set, the actual drive motor torque set is calculated, thereby obtaining the drive motor power set, which includes: Calculate the actual wheel end torque WT, WT = FtR1 × WR / FE / FR, where WT represents the actual wheel end torque in Nm; WR represents the tire rolling radius; FE represents the main reducer efficiency; and FR represents the main reducer speed ratio. The actual wheel-end torque WT and the engine torque set Substitute each number in the formula into MGT=(WT-ET×K / (K+1)×0.98) / GR / GE to calculate the actual torque set of the drive motor. ; The drive motor speed MGS and the actual torque data set of the drive motor are used to determine the speed. Substituting MGP=MGS×MGT / 9549, calculate the power set of the drive motor. .

[0017] In one implementation, the drive power consumption is obtained based on FtR1 and the current vehicle speed; the battery storage power is obtained based on the drive motor power set; and the engine combustion power is obtained based on the engine speed set and engine torque set. Multiple charging efficiencies are then calculated, and the maximum value is selected as the best charging efficiency. This includes: The driving power consumption DP is obtained based on FtR1 and the current vehicle speed. DP = FtR1 × v / 3.6 / 1000, and the unit of DP is kW. Drive motor power set Substitute each number into the formula: BP = MGP × MGE, where BP represents the battery storage power in kW and MGE represents the motor efficiency. After calculation, obtain the battery storage power data set. Based on engine speed data set and engine torque data set And the formula OI=ES×ET / 9549, to obtain the engine combustion power data set; The sum of the driving power consumption and the battery storage power divided by the corresponding engine combustion power equals the energy replenishment efficiency EA=(DP+BP) / OI, where EA is the energy replenishment efficiency. After calculation, m energy replenishment efficiencies will be obtained, and the maximum value is taken as the good energy replenishment efficiency.

[0018] The beneficial effects of the technical solutions provided in this application include at least the following: The direct-drive charging method of this application first establishes the curve relationship between various vehicle speeds and the maximum driving torque at each wheel end. Then, it obtains the maximum driving torque at the wheel end at the current vehicle speed and discretizes it into several parts. All of these parts are compared with the required driving torque at the wheel end, and discrete data greater than the required driving torque at the wheel end are obtained to form a set of candidate points. For each candidate point, three power values ​​are obtained: driving power consumption, battery storage power, and engine combustion power. Multiple charging efficiencies are calculated, and the maximum value is selected as the good charging efficiency. After obtaining the good charging efficiencies corresponding to all candidate points, the good charging efficiencies corresponding to all candidate points are compared, and the maximum value is selected as the optimal charging efficiency at the current vehicle speed. Based on the candidate point corresponding to the optimal charging efficiency, the optimal actual driving torque at the wheel end is determined, thereby optimizing the overall efficiency of the engine and motor, maximizing energy utilization, and significantly saving energy. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart of the direct drive power supply method provided in the embodiments of this application; Figure 2 This is a schematic diagram of the overall vehicle architecture of a hybrid vehicle; Figure 3 This application provides a curve showing the relationship between vehicle speed and maximum drive torque at the wheel end. Figure 4 A graph showing the system efficiency at various vehicle speeds and under various driving torques. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0022] This application provides a direct-drive power-splitting method for hybrid vehicles, which optimizes the overall efficiency of the engine and motor during the power-splitting process in direct-drive mode, thereby saving energy.

[0023] First, such as Figure 2 The following is a brief introduction to the overall vehicle architecture of hybrid vehicles.

[0024] The vehicle architecture consists of an engine (with starter motor), torsional damper, hybrid powertrain (planetary gear set + AMT + MG1 + MG2), motor controller, power battery, main reducer, tires, etc.

[0025] The vehicle CAN network architecture is divided into vehicle CAN and hybrid CAN. Vehicle CAN can be understood as a derivative of traditional fuel vehicle communication, consisting of communication between traditional components such as ECU, TCU, ABS, HCU, and LCD instrument panel. Hybrid CAN focuses on new energy systems, consisting of communication between new energy components such as MCU, BMS, and HCU.

[0026] Specifically, the ECU (Engine Control Unit) is responsible for managing the operation of a conventional internal combustion engine.

[0027] The TCU (Transmission Control Unit) is used to control the shifting logic of automatic transmissions (such as AT, CVT, DCT).

[0028] The HCU (Hybrid Control Unit) is the "brain" of a hybrid power system, coordinating the energy management of the engine, electric motor, and battery.

[0029] MCU (Motor Control Unit) is used to control the operation of electric motors, enabling drive and energy recovery.

[0030] ABS (Anti-lock Braking System) is used to prevent wheels from locking up during emergency braking, maintaining tire rolling contact with the ground, thereby maintaining steering ability and shortening braking distance.

[0031] A BMS (Battery Management System) is used to monitor and manage the status of a power battery (such as voltage, current, temperature, SOC / SOH, etc.), ensuring safe and efficient battery operation and optimizing battery life.

[0032] Secondly, the functional offloading architecture will be introduced.

[0033] Hybrid electric vehicles (HEVs) can be categorized into three main types based on their powertrain architecture: series, parallel, and series-parallel (SPP). The power-split architecture is a type of SPP. In this architecture, power distribution is achieved through a planetary gear set that couples the engine and motor. The engine's power is divided into two parts: directly driving the wheels (mechanical path) and driving the generator to produce electricity (electrical path). The motor outputs power as needed, resulting in seamless power switching. In direct-drive mode, HEVs replenish the battery by utilizing excess power to recharge it via the drive motor (energy recovery not caused by braking).

[0034] Finally, let's introduce the engine direct drive mode.

[0035] When the vehicle is traveling at high speeds (e.g., above 100 km / h), a pneumatic locking device within the hybrid powertrain quickly inflates the air chamber, pressing the friction plates together to achieve a clamping effect. The friction plates are connected to the generator shaft via splines, ultimately locking the generator shaft and enabling direct-drive mode. In direct-drive mode, the engine drives the wheels directly through the hybrid powertrain via a mechanical transmission path, typically used during high-speed cruising and other high-speed conditions.

[0036] like Figure 1 As shown, this application discloses an embodiment of a direct-drive power-splitting method for a hybrid vehicle power split architecture. The direct-drive power-splitting method includes the following steps: S1: Select several vehicle speeds within the speed range of the hybrid vehicle to obtain the curve relationship between vehicle speed and maximum driving torque at the wheel end.

[0037] S2: Based on the current vehicle status, obtain the required wheel-end drive torque and the maximum wheel-end drive torque at the current vehicle speed. Discretize these discretized data into several parts. Compare each discretized data part with the required wheel-end drive torque, and find the discretized data that is greater than the required wheel-end drive torque to form a set of candidate points. Specifically, the current vehicle status includes, but is not limited to, vehicle speed. Specifically, the discretized maximum wheel-end drive torque at the current vehicle speed corresponds to the actual wheel-end drive torque. The required wheel-end drive torque is the force that overcomes the wheel-end driving resistance, i.e., the force that maintains the normal driving output of the vehicle. Only when the actual wheel-end drive torque is greater than the required wheel-end drive torque is the condition of power surplus met, and only then can supplemental power be provided while ensuring normal vehicle driving.

[0038] S3: After selecting a candidate point from the set of candidate points, calculate the drive power consumption based on the candidate point. Discretize the optimal engine power into several parts. Combine the candidate point with the battery power storage set and the corresponding engine combustion power set to calculate. Divide the sum of the drive power consumption and the battery power storage set by the engine combustion power set to obtain multiple charging efficiencies. Find the maximum value as the good charging efficiency point. Specifically, each candidate point corresponds to discrete data of the maximum wheel-end drive torque at the current vehicle speed. Once the candidate point is determined, the drive power consumption is a fixed value. The data in the battery power storage set and the engine combustion power set correspond one-to-one, meaning they are equal in quantity and used in pairs when calculating charging efficiency. Specifically, the sum of the drive power consumption and the battery power storage set divided by the corresponding engine combustion power equals the charging efficiency. Substitute the drive power consumption, battery power storage set, and engine combustion power set into the calculation to obtain multiple charging efficiencies. Find the maximum value as the good charging efficiency.

[0039] S4: Similarly, calculate the optimal charging efficiency for the remaining candidate points, compare the optimal charging efficiency for all candidate points, and find the maximum value as the optimal charging efficiency at the current vehicle speed. Furthermore, based on the candidate points corresponding to the optimal charging efficiency, determine the optimal actual drive torque at the wheel end, thereby guiding the engine control to achieve the optimal overall efficiency of the engine and electric motor.

[0040] It's worth noting that without recharging, the actual driving torque at the wheel ends equals the required driving torque, meaning the actual driving torque is just enough for propulsion. However, when recharging is needed, the actual driving torque at the wheel ends must exceed the required driving torque to provide surplus power for recharging. However, determining exactly how much greater the actual driving torque should be than the required driving torque is uncertain. Therefore, through calculations S2, S3, and S4, the optimal recharging efficiency point, the corresponding candidate points for optimal recharging efficiency, and the optimal actual driving torque at the wheel ends are obtained. This ensures that the optimal actual driving torque at each current vehicle speed is used, simultaneously guaranteeing the hybrid vehicle's operation in direct drive mode and recharging, while also achieving optimal overall efficiency of the engine and motor, resulting in the highest energy utilization rate.

[0041] Specifically, the candidate for optimal charging efficiency differs from some hybrid vehicles on the market that pursue the maximization of charging power (i.e., the difference between the actual driving torque at the wheel end and the driving torque required at the wheel end). Instead, it pursues optimal charging efficiency, achieving the optimal overall efficiency of the engine and motor, and realizing optimal energy utilization.

[0042] The direct-drive charging method of this application first establishes the curve relationship between various vehicle speeds and the maximum drive torque at each wheel end. Then, it obtains the maximum drive torque at the wheel end at the current vehicle speed and discretizes it into several parts. All of these parts are compared with the required drive torque at the wheel end, and discrete data exceeding the required drive torque are obtained to form a set of candidate points. For each candidate point, three power parameters are obtained: drive power consumption, battery storage power, and engine combustion power. Multiple charging efficiencies are calculated, and the maximum value is selected as the optimal charging efficiency. After obtaining the optimal charging efficiencies for all candidate points, the optimal charging efficiency is compared among all candidate points, and the maximum value is selected as the optimal charging efficiency at the current vehicle speed. Based on this, the method further refines the calculation. The candidate point corresponding to the optimal charging efficiency is determined, and the optimal actual driving torque at the wheel end is obtained, so that the overall efficiency of the engine and motor is optimized, the energy utilization rate is maximized, and energy is greatly saved.

[0043] In one embodiment, in step S1, several vehicle speeds are selected within the speed range of the hybrid vehicle to obtain the curve relationship between the vehicle speed and the maximum driving torque at the wheel end (see...). Figure 3 ),Include: S11: Select several vehicle speeds within the speed range of the hybrid vehicle and calculate the set of drive motor speeds; S12: Based on the set of drive motor speeds, obtain the set of drive motor peak torques through Lagrange polynomial interpolation; S13: Based on the peak torque set of the drive motor, and according to the fact that the peak torque of the engine is coupled with the peak torque of the drive motor at the output shaft of the hybrid powertrain after being output through the planetary gear set, the maximum drive torque set at the wheel end is calculated, and the curve relationship between vehicle speed and maximum drive torque at the wheel end is obtained.

[0044] Further, in step S11, several vehicle speeds are selected within the speed range of the hybrid vehicle, and a set of drive motor speeds is calculated, including: Based on the formula MGS = v / 3.6 / WR×60 / π / 2×FR×GR, substituting the selected n vehicle speeds into this formula yields a dataset of n MGS values. ; Where MGS represents the drive motor speed in rpm; v represents the vehicle speed in km / h, which is a known quantity; GR represents the AMT speed ratio in the power split architecture, which is a known quantity; FR represents the main reducer speed ratio in the power split architecture, which is a known quantity; and WR represents the tire rolling radius, which is a known quantity.

[0045] In the direct-drive power supply method of this application, step S11 is mainly to convert each vehicle speed into the drive motor speed and obtain the corresponding drive motor speed set.

[0046] Further, in step S12, based on the set of drive motor speeds, the set of drive motor peak torques is obtained through Lagrange polynomial interpolation, including: Construct the Lagrange interpolation basis function related to the speed of the drive motor. : Equation (1); where, ; Calculate the peak torque of the drive motor ; Equation (2); Will Substituting each number in the equation into equations (1) and (2), we obtain the set of peak torque numbers for the drive motor. ; in, : Motor external characteristic speed sequence, in rpm, which are known quantities; : Motor external characteristic torque sequence, unit Nm, is a known quantity; Formula (2) is calculated by adding multiple sub-items, and each sub-item is substituted into and The subscript corresponds to, i.e. correspond And so on, correspond Specifically, the motor's external characteristic speed sequence and external characteristic torque sequence are both known quantities once the motor model is determined.

[0047] The direct-drive power supply method of this application obtains the peak torque set of the drive motor through Lagrange polynomial interpolation based on the set of drive motor speeds.

[0048] Further, in step S13, based on the peak torque set of the drive motor, the maximum drive torque set at the wheel end is calculated, including: According to the relationship between the maximum driving torque Ft at the wheel end and the peak torque MGTM of the drive motor (3); Ft=(ETM×K / (K+1)×0.98+MGTM×GR×GE)×FR×FE / WR, equation (3); Set the peak torque data of the drive motor Substituting each number into equation (3), we obtain the set of maximum driving torque numbers at the wheel ends. ; Where Ft is in Nm; ETM represents the engine peak torque in Nm, which is a known quantity; K represents the planetary gear set characteristic parameter of the power split architecture, which is a known quantity; GR represents the AMT speed ratio in the power split architecture, which is a known quantity; GE represents the AMT mechanical efficiency, which is a known quantity; FE represents the final drive efficiency, which is a known quantity; and WR represents the tire rolling radius, which is a known quantity.

[0049] In the direct-drive power supply method of this application, step S13 mainly involves converting the peak torque set of the drive motor into the maximum drive torque set at the wheel end.

[0050] Further, in step S13, obtaining the curve relationship between vehicle speed and maximum drive torque at the wheel end includes: By performing step-by-step calculations in steps S11, S12, and S13, a maximum driving torque at one wheel end corresponds to a vehicle speed, thus obtaining the curve relationship between vehicle speed and maximum driving torque at the wheel end.

[0051] In the direct-drive power replenishment method of this application, the entire step S1 is completed in advance, with the aim of obtaining the curve relationship between vehicle speed and maximum drive torque at the wheel end.

[0052] In one embodiment, in step S2, the required wheel-end driving torque is obtained based on the current vehicle state; the maximum wheel-end driving torque at the current vehicle speed is obtained and discretized into several parts, all of which are compared with the required wheel-end driving torque to obtain discrete data greater than the required wheel-end driving torque, forming a set of candidate points, including: S21: Based on the wheel-end demand drive torque calculation module in VCU, the wheel-end demand drive torque Ftx is obtained according to the current vehicle speed, pedal opening, and NRD gear status.

[0053] S22: Based on the current vehicle speed, and the curve relationship between vehicle speed and maximum drive torque at the wheel end, obtain the maximum drive torque at the wheel end Ft0 at the current vehicle speed.

[0054] S23: Discretize the maximum driving torque at the wheel end at the current vehicle speed. Discretize the maximum driving torque at the wheel end at the current vehicle speed at equal intervals of m parts to obtain m discrete maximum driving torques at the wheel end, which are 1, Ft0 / m, 2Ft0 / m·····h×Ft0 / m······1×Ft0; where 1<h<m, and h and m are both positive integers.

[0055] S24: When hFt0 / m < Ftx < (h+1) × Ft0 / m, the set of points to be selected is FtR = {(h+1) × Ft0 / m, (h+2) × Ft0 / m, ..., 1 × Ft0}.

[0056] The direct-drive charging method of this application, under the condition of known vehicle speed, in order to determine how much larger the actual driving torque at the wheel end should be than the required driving torque at the wheel end, this application uses the maximum driving torque at the wheel end at the current vehicle speed for discretization, and compares the discretized data with the current required driving torque at the wheel end to filter out the surplus actual driving torque at the wheel end that can be charged. The idea is ingenious and novel.

[0057] Specifically, the required driving torque at the wheel end is the force needed to overcome the driving resistance at the wheel end and maintain the normal driving output of the vehicle. The actual driving torque at the wheel end is the actual force output by the various assemblies of the vehicle working together. If the actual torque is greater than the required torque, it manifests as improved power / higher SOC; if the actual torque is less than the required torque, it manifests as reduced power / lower SOC. Since the purpose of this patent is to charge the vehicle while meeting the wheel end requirements, the points where the actual driving torque at the wheel end is less than the required driving torque at the wheel end are eliminated, while the points where the actual driving torque at the wheel end is greater than the required driving torque at the wheel end are retained.

[0058] In one embodiment, in step S3, after selecting a candidate point from the candidate point set, the drive power consumption is calculated based on the candidate point. The optimal engine power is discretized into several parts to obtain a battery power storage set and a corresponding engine combustion power set. The sum of the drive power consumption and the battery power storage set is divided by the engine combustion power set to obtain multiple charging efficiencies. The maximum value is found as a good charging efficiency, including: S31: Select a candidate point FtR1 from the set of candidate points.

[0059] S32: Discretize the engine starting power (40kW) and the engine optimal power into m parts to obtain a discrete set of engine power; based on the discrete set of engine power, obtain the set of engine speeds through Lagrange polynomial interpolation, and then calculate the set of engine torques. Specifically, the optimal engine power is a constant obtained by calculating the optimal economic curve of the engine. The calculation method of the optimal economic curve will not be elaborated here. In this application, the optimal engine power is taken as a known quantity.

[0060] S33: Based on FtR1, calculate the actual torque at the wheel end. According to the charging relationship (the engine drives the supply of power for walking and charging), combine the engine torque data set to calculate the actual torque data set of the drive motor, and then obtain the power data set of the drive motor.

[0061] S34: Obtain the driving power consumption based on FtR1 and the current vehicle speed, obtain the battery storage power set based on the drive motor power set, obtain the engine combustion power set based on the engine speed set and engine torque set, and then divide the sum of the driving power consumption and battery storage power by the corresponding engine combustion power to obtain the charging efficiency. Calculate multiple charging efficiencies based on the driving power consumption, battery storage power set and engine combustion power set, and find the maximum value as the good charging efficiency.

[0062] The direct-drive charging method of this application, for each candidate point FtR1, calculates the actual wheel-end torque based on FtR1, calculates the actual drive motor torque based on the engine torque set, and then obtains the drive motor power set. Based on FtR1 and the current vehicle speed, it obtains the drive power consumption, the battery power storage set, and the engine combustion power set. Then, it calculates the charging efficiency by dividing the sum of the drive power consumption and battery power storage by the corresponding engine combustion power. Substituting the drive power consumption, battery power storage, and engine combustion power sets into these values ​​yields multiple charging efficiencies. The maximum value is selected as the optimal charging efficiency. This application obtains the optimal charging efficiency for each candidate point that meets the surplus charging conditions, until all candidate points are compared to find the maximum value as the optimal charging efficiency at the current vehicle speed. Applying this method can significantly save energy.

[0063] In one embodiment, in step S32, the engine starting power of 40 kW and the engine's optimal power are discretized into m parts to obtain a discrete set of engine power; based on the discrete set of engine power, the engine speed set is obtained through Lagrange polynomial interpolation, and then the engine torque set is calculated, including: S321: Discretize the engine's optimal power into m parts to obtain the engine power discrete set EPR; EPR=[40, 40+(EZPM-40) / m, 40+2×(EZPM-40) / m, ······, 40+1×(EZPM-40)]; EZPM represents the engine's optimal power, measured in kW. S322: Based on the discrete set of engine power (EPR), the engine speed set is obtained through Lagrange polynomial interpolation, and the engine torque set is calculated, including: Construct the Lagrange interpolation basis function related to engine power. ; Equation (4); in, ; Calculate engine speed ; Equation (5); ES indicates engine speed, measured in rpm; Substituting each number in the discrete set of engine power EPR into formulas (4) and (5), we obtain the set of engine speed numbers. ;in, : The original optimal power sequence of the engine; : The original optimal engine speed sequence; during calculation correspond And so on. correspond .

[0064] S323: Based on the engine speed data set, the engine torque data set is obtained according to the formula ET=9549×EPR / ES. .

[0065] Further, in step S33, based on FtR1, the actual torque at the wheel end is calculated. According to the charging relationship (engine-driven supply for travel and charging requirements), the actual torque of the drive motor is calculated, and then the drive motor power is calculated, including: S331: Calculate the actual wheel end torque WT, WT = FtR1 × WR / FE / FR, where WT represents the actual wheel end torque in Nm; WR represents the tire rolling radius in m, which is a known quantity; FE represents the main reducer efficiency, which is a known quantity; and FR represents the main reducer speed ratio, which is a known quantity.

[0066] S332: Sets the actual wheel end torque WT and engine torque data. Substitute each number in the formula into MGT=(WT-ET×K / (K+1)×0.98) / GR / GE to calculate the actual torque set of the drive motor. Specifically, a negative MGT indicates negative torque. WT represents a single value, K represents the planetary gear set characteristic parameter (a known quantity), GR represents the AMT speed ratio (a known quantity), and GE represents the AMT mechanical efficiency (a known quantity).

[0067] S333: Sets the drive motor speed MGS and the actual torque of the drive motor. Substituting MGP=MGS×MGT / 9549, calculate the power set of the drive motor. .

[0068] Further, in step S34, the drive power consumption is obtained based on FtR1 and the current vehicle speed; the battery power storage set is obtained based on the drive motor power set; and the engine combustion power set is obtained based on the engine speed set and engine torque set. Then, the sum of the drive power consumption and battery power storage, divided by the corresponding engine combustion power, equals the total charging efficiency. Substituting the drive power consumption, battery power storage, and engine combustion power sets into this equation yields multiple total charging efficiencies. The maximum value is selected as the good charging efficiency, including: The driving power consumption DP is obtained based on FtR1 and the current vehicle speed. DP = FtR1 × v / 3.6 / 1000, and the unit of DP is kW.

[0069] Drive motor power set Substitute each number into the equation, BP = MGP × MGE, where BP is the battery storage power in kW and MGE represents the motor efficiency, which is a known quantity. After calculation, the battery storage power set is obtained.

[0070] Based on engine speed data set and engine torque data set And the formula OI=ES×ET / 9549 is used to obtain the engine combustion power set; specifically, there is a corresponding relationship between engine speed and engine torque, and ES1 corresponds to ET1 in the calculation.

[0071] The total energy replenishment efficiency is calculated as EA = (DP + BP) / OI, where EA is the energy replenishment efficiency. After calculation, m energy replenishment efficiencies are obtained, and the maximum value is taken as the good energy replenishment efficiency.

[0072] This good charging efficiency corresponds to a candidate point with a known vehicle speed.

[0073] Further, in step S4, the same process is repeated to calculate the good charging efficiency corresponding to the remaining candidate points. The good charging efficiency corresponding to all candidate points is compared, and the maximum value is found as the optimal charging efficiency at the current vehicle speed. This includes: By performing a series of calculations in S2, S3, and S4, a good power replenishment efficiency is obtained for a candidate point with a known vehicle speed. The same calculation is then performed to obtain the good power replenishment efficiency for the remaining candidate points. That is, each candidate point in the candidate point set FtR={(h+1)×Ft0 / m, (h+2)×Ft0 / m, ..., 1×Ft0} is calculated in the same way, resulting in a total of mh good power replenishment efficiencies. The maximum value among the mh good power replenishment efficiencies is then selected to obtain the optimal power replenishment efficiency point, which indicates that the overall efficiency of the engine plus the drive motor is optimal at the known vehicle speed.

[0074] Accordingly, the candidate point corresponding to the optimal charging efficiency point is obtained, and the optimal actual driving torque at the wheel end corresponding to the candidate point is known. In this way, the optimal actual driving torque at the wheel end is used for each current vehicle speed, which ensures that the hybrid vehicle can operate and charge in direct drive mode, and also achieves the overall efficiency of the engine and motor to be optimal, thus achieving the highest energy utilization rate.

[0075] Specifically, the candidate for optimal charging efficiency differs from some hybrid vehicles on the market that pursue the maximization of charging power (i.e., the difference between the actual driving torque at the wheel end and the driving torque required at the wheel end). Instead, it pursues optimal charging efficiency, achieving the optimal overall efficiency of the engine and motor, and realizing optimal energy utilization.

[0076] The curves showing the system efficiency at various vehicle speeds and under different driving torques correspond to... Figure 4 .

[0077] Preferably, both m and n in the text are 20.

[0078] The direct-drive charging method of this application can significantly save energy. When hybrid vehicles adopt the direct-drive charging method of this application, the hub CHTC energy consumption test is completed in accordance with the test method in "GB / T 19754 Test Method for Energy Consumption of Heavy-Duty Hybrid Electric Vehicles". After verification and improvement (corresponding to the direct-drive charging method of this application), the average engine efficiency and drive motor efficiency are shown in Table 1 below. The engine efficiency is improved by 0.73%, the drive motor efficiency is improved by 1.62%, and the overall efficiency is improved by 2.35%. In practical applications, it can save 0.13L / 100km of fuel, which has extremely high economic value.

[0079] Table 1

[0080] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0081] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0082] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A direct-drive power supply method for a hybrid vehicle power split architecture, characterized in that, Includes the following steps: Several vehicle speeds were selected within the speed range of the hybrid vehicle to obtain the curve relationship between vehicle speed and maximum driving torque at the wheel end. The required driving torque at the wheel end is obtained based on the current vehicle status; the maximum driving torque at the wheel end at the current vehicle speed is obtained and discretized into several parts, all of which are compared with the required driving torque at the wheel end to obtain discrete data that are greater than the required driving torque at the wheel end, forming a set of candidate points; After selecting a candidate point from the candidate point set, the drive power consumption is calculated based on the candidate point. The optimal engine power is discretized into several parts to obtain the battery power storage set and the corresponding engine combustion power set. The sum of the drive power consumption and the battery power storage set is divided by the engine combustion power set to obtain multiple charging efficiencies. The maximum value is found as the good charging efficiency. Similarly, calculate the good charging efficiency corresponding to the remaining candidate points, compare the good charging efficiency corresponding to all candidate points, and find the maximum value as the optimal charging efficiency at the current vehicle speed.

2. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 1, characterized in that, Within the speed range of the hybrid vehicle, several vehicle speeds are selected to obtain the curve relationship between vehicle speed and maximum wheel-end drive torque, including: Within the speed range of hybrid vehicles, select several vehicle speeds and calculate the set of drive motor speeds. Based on the set of drive motor speeds, the set of peak torques of the drive motors is obtained by Lagrange polynomial interpolation. Based on the peak torque set of the drive motor, and considering that the peak torque of the engine is coupled with the peak torque of the drive motor at the output shaft of the hybrid powertrain after being output through the planetary gear set, the maximum drive torque set at the wheel end is calculated, and the curve relationship between vehicle speed and maximum drive torque at the wheel end is obtained.

3. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 2, characterized in that, Within the speed range of hybrid vehicles, select several vehicle speeds and calculate a set of drive motor speeds, including: Based on the formula MGS = v / 3.6 / WR×60 / π / 2×FR×GR, substituting the selected n vehicle speeds into this formula yields a dataset of n MGS values. ; Where MGS represents the drive motor speed in rpm; v represents the vehicle speed in km / h; GR represents the AMT speed ratio in the power split architecture; FR represents the main reducer speed ratio in the power split architecture; and WR represents the tire rolling radius.

4. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 3, characterized in that, Based on the set of drive motor speeds, the set of peak torques of the drive motors is obtained through Lagrange polynomial interpolation, including: Construct the Lagrange interpolation basis function related to the speed of the drive motor. : ； Calculate the peak torque of the drive motor ; ; Will Substituting each number into the given data, we obtain the set of peak torque values ​​for the drive motor. ; in, Motor external characteristic speed sequence, in rpm; Motor external characteristic torque sequence, unit Nm; during calculation correspond And so on. correspond .

5. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 4, characterized in that, Based on the peak torque set of the drive motor, the maximum drive torque set at the wheel end is calculated, including: Based on the relationship between the maximum driving torque Ft at the wheel end and the peak torque MGTM of the drive motor; Ft=(ETM×K / (K+1)×0.98+MGTM×GR×GE)×FR×FE / WR; Set the peak torque data of the drive motor Substitute each number into the set of maximum drive torque values ​​at the wheel end to obtain the set of values. ; Where Ft is in Nm; ETM represents the engine peak torque in Nm; K represents the planetary gear set characteristic parameters; GE represents the AMT mechanical efficiency; and FE represents the final drive efficiency.

6. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 1, characterized in that, The required wheel-end drive torque is obtained based on the current vehicle status; the maximum wheel-end drive torque at the current vehicle speed is obtained and discretized into several parts, all of which are compared with the required wheel-end drive torque. Discrete data greater than the required wheel-end drive torque are obtained to form a set of candidate points, including: Based on the wheel-end demand drive torque calculation module in the VCU, the current wheel-end demand drive torque Ftx is obtained according to the current vehicle speed, pedal opening, and NRD gear status. Based on the current vehicle speed, and using the curve relationship between vehicle speed and maximum wheel-end driving torque, obtain the maximum wheel-end driving torque Ft0 at the current vehicle speed; Discretize the maximum driving torque at the wheel end at the current vehicle speed. Discretize the maximum driving torque at the wheel end at the current vehicle speed at equal intervals of m parts from 1 Nm to m discrete maximum driving torque at the wheel end, which are 1, Ft0 / m, 2Ft0 / m·····h×Ft0 / m······1×Ft0; where 1 < h < m. When hFt0 / m<Ftx<(h+1)×Ft0 / m, the set of points to be selected is FtR={(h+1)×Ft0 / m、(h+2)×Ft0 / m、……、1×Ft0}.

7. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 1, characterized in that, Select a candidate point, calculate the drive power consumption, discretize the optimal engine power into several parts, obtain the battery storage power set and the corresponding engine combustion power set, obtain multiple charging efficiencies, find the maximum value as the good charging efficiency, including: From the set of candidate points, select one candidate point FtR1; The engine power discrete set is obtained by discretizing the engine starting power of 40 kW and the engine optimal power by m parts; based on the engine power discrete set, the engine speed set is obtained by Lagrange polynomial interpolation, and then the engine torque set is calculated. Based on FtR1, the actual torque at the wheel end is calculated, and combined with the engine torque set, the actual torque set of the drive motor is calculated, thereby obtaining the drive motor power set. The driving power consumption is obtained based on FtR1 and the current vehicle speed. The battery storage power is obtained based on the drive motor power set. The engine combustion power is obtained based on the engine speed set and engine torque set. Multiple charging efficiencies are then calculated, and the maximum value is found as the good charging efficiency.

8. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 7, characterized in that, The engine power discrete set is obtained by discretizing the engine starting power (40kW) and the engine optimal power (m parts). Based on the engine power discrete set, the engine speed set is obtained by Lagrange polynomial interpolation, and then the engine torque set is calculated, including: The engine starting power of 40 kW is discretized into m parts from the engine's optimal power to obtain the engine power discrete set EPR; EPR=[40, 40+(EZPM-40) / m, 40+2×(EZPM-40) / m, ······, 40+1×(EZPM-40)]; Where EZPM represents the engine's peak optimal power, in kW; Based on the discrete set EPR of the engine's optimal power, the engine speed set is obtained through Lagrange polynomial interpolation, and the engine torque set is calculated, including: Constructing Lagrange interpolation basis functions ; ； Calculate engine speed ; ； ES indicates engine speed, measured in rpm; Substituting each number in the discrete set of engine power EPR, we obtain the set of engine speeds. ;in, : The original optimal power sequence of the engine; : The original optimal speed sequence of the engine; Based on the engine speed data set, the engine torque data set is obtained according to the formula ET=9549×EPR / ES. .

9. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 8, characterized in that, Based on FtR1, the actual wheel-end torque is calculated, and combined with the engine torque set, the actual drive motor torque set is calculated, thus obtaining the drive motor power set, which includes: Calculate the actual wheel end torque WT, WT = FtR1 × WR / FE / FR, where WT represents the actual wheel end torque in Nm; WR represents the tire rolling radius; FE represents the final drive efficiency; and FR represents the final drive speed ratio. The actual wheel-end torque WT and the engine torque set Substitute each number in the formula into MGT=(WT-ET×K / (K+1)×0.98) / GR / GE to calculate the actual torque set of the drive motor. ; The drive motor speed MGS and the actual torque data set of the drive motor are used to determine the speed. Substituting MGP=MGS×MGT / 9549, calculate the power set of the drive motor. .

10. The direct-drive power replenishment method for a hybrid vehicle power split architecture as described in claim 9, characterized in that, Based on FtR1 and the current vehicle speed, the drive power consumption is obtained; based on the drive motor power data set, the battery storage power data set is obtained; based on the engine speed data set and engine torque data set, the engine combustion power data set is obtained. Multiple charging efficiencies are then calculated, and the maximum value is selected as the best charging efficiency, including: The driving power consumption DP is obtained based on FtR1 and the current vehicle speed. DP = FtR1 × v / 3.6 / 1000, and the unit of DP is kW. Drive motor power set Substitute each number into the formula: BP = MGP × MGE, where BP represents the battery storage power in kW and MGE represents the motor efficiency. After calculation, obtain the battery storage power data set. Based on engine speed data set and engine torque data set And the formula OI=ES×ET / 9549, to obtain the engine combustion power data set; The sum of the driving power consumption and the battery storage power divided by the corresponding engine combustion power equals the energy replenishment efficiency EA=(DP+BP) / OI, where EA is the energy replenishment efficiency. After calculation, m energy replenishment efficiencies will be obtained, and the maximum value is taken as the good energy replenishment efficiency.

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