Dynamic torque control method for hybrid electric vehicle

Abstract

The invention discloses a hybrid electric vehicle torque dynamic control method, which relates to the technical field of hybrid electric vehicles, and has the main design conception that aiming at a driving framework and a control mode of a hybrid electric vehicle, after torque required by a driver is received, the torque required by the driver is controlled; different dynamic torque coordination distribution control strategies are adopted for the three different working condition states of middle mode switching, middle gear switching and steady-state operation, so that torque distribution of an engine, a generator and a driving motor is dynamically coordinated, corresponding torque control is executed according to the distribution result, and the whole vehicle has excellent driving experience.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid vehicle, and in particular to a method for dynamic torque control of a hybrid vehicle. Background Art

[0002] The target hybrid system is a P2.5+P4 hybrid solution, and its powertrain consists of three parts: engine, 4DHT (hybrid-specific gearbox, including P2.5 motor), and rear axle electric drive assembly (including P4 motor). 4DHT is mainly composed of four clutches: C1, C2, B1, and B2. Through the combination of the four clutches, four gear ratios of the engine and two gear ratios of the P2.5 motor can be formed; among them, C1 or C2 can be selectively used as the engine clutch (i.e., K0 clutch) of the P2.5 system under different vehicle speed conditions; and the rear axle electric drive assembly can work relatively independently.

[0003] In addition, the control module of the whole vehicle generally includes the vehicle controller VCU, the engine controller ECU, the 4DHT hybrid-specific transmission controller HTCU and the P2.5+P4 dual-motor controller. Among them, the HTCU serves as a two-in-one controller of the 4AT transmission controller TCU and the vehicle hybrid mode controller HCU.

[0004] Based on the above hybrid architecture, four major working modes can be formed, including pure electric rear-wheel drive and pure electric four-wheel drive. According to different torque distribution methods, pure electric four-wheel drive can also include pure electric front-wheel drive and pure electric neutral; while parallel four-wheel drive can include parallel front-wheel drive and pure fuel mode, and series rear-wheel drive also includes subdivided hybrid working modes such as parking power generation.

[0005] At present, the main control method of steady-state driving torque distribution based on the whole vehicle P2.5+P4 hybrid solution is that the HTCU receives the total wheel-end torque demand of the VCU and distributes it to the P2 motor, P4 motor and engine according to the current working mode, power, vehicle speed, power source status, etc. to complete the steady-state driving torque distribution. However, different working conditions will be encountered when distributing the steady-state torque of the whole vehicle, so there is no better solution that meets expectations for how to coordinate the dynamic torque distribution. Summary of the invention

[0006] In view of the above, the present invention aims to provide a method for dynamic torque control of a hybrid vehicle to solve the above-mentioned technical problems.

[0007] The technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for dynamic torque control of a hybrid vehicle, which includes:

[0009] After receiving the target required torque, determine the current working condition;

[0010] Dynamically coordinate and distribute torque according to different current operating conditions, wherein the current operating conditions include: operating mode switching, gear switching, and steady-state operation;

[0011] While dynamically coordinating and distributing torque, the battery energy is managed and controlled;

[0012] After the torque distribution result is arbitrated, the corresponding torque control is executed.

[0013] In at least one possible implementation, dynamically coordinating and distributing torque according to different current operating conditions includes:

[0014] If it is determined that the current driving mode is being switched, at least one of the following torque control measures is taken: torque migration, slope limitation, auxiliary speed and torque regulation;

[0015] If it is determined that the gear switching process is currently in progress, at least one of the following torque control measures is adopted according to different gear control stages: four-gear torque processing, auxiliary speed regulation and torque reduction, and process protection torque reduction; wherein the gear control stage is divided into an oil filling torque alternation stage, a speed synchronization stage, and a recovery stage;

[0016] If it is determined that the vehicle is currently in steady-state operation, then after determining that the accelerator pedal opening meets the established stability threshold and there is no wheel-end torque switching demand, only the torque slope limiting measure is adopted; after determining that there is a positive and negative wheel-end torque switching demand, at least one of the following torque control measures is adopted: zero-crossing control, torque slope limiting.

[0017] In at least one possible implementation, the torque slope limiting method includes:

[0018] Read the maximum allowable rising and / or falling torque slope, and filter it according to the predetermined gradient according to the current target demand torque to obtain the intermediate target demand torque;

[0019] Perform first-order inertia filtering on the intermediate target demand torque to obtain the final target demand torque.

[0020] In at least one possible implementation, the controlling of battery energy includes:

[0021] Read the maximum allowed long-time charge and discharge power limit and short-time charge and discharge power limit in real time;

[0022] Real-time calculation of the maximum allowable charge and discharge power value of the power battery under the current working conditions;

[0023] When the maximum charge and discharge power value rises to the preset value before the short-time charge and discharge power limit value, the maximum power timing function is started; if the timing exceeds the predetermined time threshold, the maximum allowable charge and discharge power value is smoothly transitioned to the long-time discharge power limit value;

[0024] When the maximum charge and discharge power value drops below the long-term charge and discharge power limit value and exceeds the predetermined cumulative time, the maximum allowable charge and discharge power value is smoothly restored to the short-term discharge power limit value.

[0025] In at least one possible implementation, the control method further includes:

[0026] When the vehicle is in a driving state, the driving power is preferentially allocated to the first motor;

[0027] Among them, the driving power limit value of the first motor is the maximum allowable discharge power value of the battery + the power generated by the second motor - the power of the vehicle accessories;

[0028] The driving power limit value of the second motor is the maximum allowable discharge power value of the battery - the current driving power of the first motor - the power of the vehicle accessories.

[0029] In at least one possible implementation, the control method further includes:

[0030] When the vehicle is in an energy recovery power generation state, the power generation power is preferentially allocated to the second motor;

[0031] The power limit of the second motor is the maximum allowable charging power of the battery + the power of the vehicle accessories.

[0032] The power generation limit value of the first motor is the maximum allowable discharge power value of the battery - the current power generation power of the second motor - the power of the vehicle accessories.

[0033] Compared with the prior art, the main design concept of the present invention is that, for the drive architecture and control mode of the hybrid vehicle, after receiving the torque required by the driver, different dynamic torque coordination distribution control strategies are adopted for the three different operating conditions of mode switching in progress, gear switching in progress, and steady-state operation, so as to dynamically coordinate the torque distribution of the engine, generator, and drive motor, and perform corresponding torque control according to the distribution results, so that the whole vehicle has an excellent driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described below with reference to the accompanying drawings, in which:

[0035] Figure 1 A schematic diagram of a method for dynamic torque control of a hybrid vehicle provided by an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a dual-motor power control method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0038] The present invention proposes an embodiment of a method for dynamic torque control of a hybrid vehicle. Specifically, Figure 1 shown, including:

[0039] Step S1, after receiving the target required torque, determine the current working condition;

[0040] Step S2, dynamically coordinating and distributing torque according to different current operating conditions, wherein the current operating conditions include: operating mode switching, gear switching, and steady-state operation;

[0041] Step S3: while dynamically coordinating and distributing the torque, controlling the battery energy;

[0042] Step S4: After the torque distribution result is arbitrated, corresponding torque control is performed.

[0043] In combination with the above embodiment, specifically, after receiving the driver's required torque (i.e., the torque demand generated by the driver's intention to perform a corresponding operation in a certain driving state), the hybrid transmission controller HTCU will distinguish and enter different dynamic torque coordination distribution control modes corresponding to three states. The three operating states are as follows:

[0044] (1) Operation mode switching is in progress;

[0045] (2) Gear shifting in progress;

[0046] (3) Steady-state operation (no mode switching or gear switching).

[0047] After processing the required torque, if it is determined that the current driving mode is switched, there are three dynamic torque control measures, namely torque migration, slope limitation, and auxiliary speed and torque regulation.

[0048] If it is determined that the gear shift is in progress, three dynamic torque control measures are selected according to different gear control stages, including four-gear related torque processing, auxiliary speed regulation and torque reduction, or process protection torque reduction. Specifically, the gear control stage can be basically divided into three stages: oil filling torque alternation stage, speed synchronization stage, and recovery stage (clutch clamping control).

[0049] In steady-state operation, if the accelerator pedal is relatively stable (which can be quantified by the accelerator pedal opening value) and there is no need to switch between positive and negative wheel-end torque, there is only a torque slope protection function, that is, a torque slope limiting measure. If there is a tipin or tip out operation and the positive and negative wheel-end torque switching is triggered, there are zero-crossing control measures (a control strategy that suppresses motor jitter near zero torque) and preset slope limiting measures (referring to the gradient control of the torque response allowed by the engine or motor in the process of responding to torque regulation (the maximum amplitude of the torque response allowed per unit time), which is limited by the characteristics of the motor or engine itself) to improve the driving quality when switching between positive and negative wheel-end torque.

[0050] It can be further explained that in the above-mentioned dynamic torque coordination distribution process, the wheel end torque and the torque of the power source can be smoothed and slope limited.

[0051] Among them, the overall filtering and slope limiting of the wheel-end torque have been completed in the VCU. The HTCU only performs the aforementioned zero-crossing control and does not impose a secondary limit on the torque command of the VCU. When the HTCU detects the driver's Tip in, Tip out and predicts that the wheel-end torque will switch between positive and negative values, the zero-crossing control function will be activated. In the zero-crossing control area, the power source torque will be subject to segmented torque slope limits to buffer the positive and negative meshing gap impacts of the transmission chain.

[0052] After HTCU distributes the wheel-end torque to EM1, EM2, and ENG in proportion according to the aforementioned torque distribution strategy, it will also limit the torque slope of these three power sources, and can use transition smoothing restrictions. The mode switching conditions mentioned above can also involve transition smoothing restrictions to prevent shocks caused by too fast torque changes, power source overload, and power source torque response that cannot keep up. In other words, based on the coordinated control of the vehicle's dynamic torque distribution, the vehicle's torque can be exerted stably and smoothly.

[0053] Here, a method of limiting the torque slope is given, which reads the maximum allowable rising / falling torque slope, and filters it according to the established gradient based on the current target demand torque to obtain the intermediate target demand torque; the intermediate target demand torque is subjected to a first-order inertia filter to obtain the final target demand torque.

[0054] As mentioned above, the specific process of dynamic torque coordination distribution is generally limited by the global power limit of the energy management function. Therefore, the present invention also proposes a basic control method for the energy management function, such as Figure 2 Partial illustration.

[0055] HTCU reads the maximum allowed long-time charge and discharge power limit and short-time charge and discharge power limit from BMS in real time. By default, HTCU enables short-time charge and discharge power limit. For example, the current short-time charge and discharge power is 10s charge and discharge power, which can be understood as the maximum allowed charge and discharge power of the battery with time limit; the aforementioned long-time charge and discharge power is the power that the power battery can charge and discharge continuously. After the battery BMS is developed and tested, the above short-time and long-time charge and discharge power can be calibrated according to different situations to obtain a map table / chart.

[0056] The TCU calculates in real time the maximum allowable charge and discharge power value currently being used by the power battery. When the maximum charge and discharge power value approaches the short-term charge and discharge power limit value, the maximum power timing function will be started. Once the timing exceeds the allowed time threshold, the maximum allowable charge and discharge power value will be smoothly transitioned to the long-term discharge power limit value.

[0057] When the maximum charge and discharge power value in use drops below the long-term charge and discharge power limit value and exceeds the predetermined cumulative time, the maximum allowable charge and discharge power value is smoothly restored to the short-term discharge power limit value.

[0058] Based on the above energy management concept combined with Figure 2 The present invention also proposes the following power allocation strategy for implementation reference:

[0059] During driving conditions, the system will prioritize allocating driving power to the EM1 motor: that is, the driving power of EM1 is limited by the maximum allowable discharge power of the battery + GCU power generation power - accessory power; while EM2 is limited by the maximum allowable discharge power of the battery - EM1 current driving power - accessory power.

[0060] To elaborate, what is described here is the maximum driving power limit allowed by the system when two motors are driving, that is, the driving power of the EM1 motor is obtained by the aforementioned maximum discharge power of the battery and the power generation power of EM2 obtained through energy control minus the accessory power of the whole vehicle (the power consumption of the whole vehicle's electrical components comes from the battery or EM2 power generation); and the maximum allowable driving power of EM2 is the maximum discharge power of the battery - the driving power of EM1 - the accessory power, which is the maximum allowable driving power limit of EM2, and the whole vehicle gives priority to EM1 driving.

[0061] When the energy recovery power generation is in operation, the system will give priority to allocating power generation to the EM2 motor: that is, the power generation of EM2 is limited by the maximum charging power allowed by the battery + the accessory power mentioned above; and under this condition, EM1 is limited by the maximum discharge power of the battery - the current power generation of EM2 - the accessory power.

[0062] In addition to the previous article further refining the power distribution according to the working conditions, it can also be added that in the driving or power generation conditions, there is a power safety factor to prevent the short-term charging and discharging power from being too large due to inaccurate values ​​of the battery, motor, and accessory power (or speed, torque, voltage, power, etc.) or inaccurate transient transition values ​​during the charging and discharging process. The EM1 motor and the EM2 motor are both limited by their respective peak power. Here is an additional explanation of the factors affecting the limited motor capacity. Under different temperatures and different battery power conditions, the battery's allowable charging and discharging power is limited. These limitations are determined by the BMS battery characteristics. Based on the battery charging and discharging capabilities, the vehicle will make restrictions on the driving and power generation conditions of the motor due to considerations of the battery capacity. Ultimately, the maximum driving power and maximum power generation power of the EM1 motor and EM2 motor can be obtained.

[0063] In summary, the main design concept of the present invention is that, for the drive architecture and control mode of the hybrid vehicle, after receiving the torque required by the driver, different dynamic torque coordination distribution control strategies are adopted for the three different operating conditions of mode switching in progress, gear switching in progress, and steady-state operation to dynamically coordinate the torque distribution of the engine, generator, and drive motor, and perform corresponding torque control according to the distribution results, so that the whole vehicle has an excellent driving experience.

[0064] If the expressions expressing orientation are mentioned in the embodiments of the present invention, they are relative concepts based on the embodiments. In addition, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b, c can be single or multiple.

[0065] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings, but the above is only a preferred embodiment of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred methods can be reasonably combined and matched into a variety of equivalent schemes by those skilled in the art without departing from or changing the design ideas and technical effects of the present invention; therefore, the present invention is not limited to the scope of implementation shown in the drawings, and all changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the specification and drawings, should be within the protection scope of the present invention.

Claims

1. A method for dynamic torque control of a hybrid vehicle, characterized in that: include: After receiving the target required torque, determine the current working condition; Dynamically coordinate and distribute torque according to different current operating conditions, wherein the current operating conditions include: operating mode switching, gear switching, and steady-state operation; While dynamically coordinating and distributing torque, the battery energy is managed and controlled; After the torque distribution result is arbitrated, the corresponding torque control is executed.

2. The method for dynamic torque control of a hybrid vehicle according to claim 1, characterized in that: The dynamic coordinated torque distribution according to different current working conditions includes: If it is determined that the current driving mode is being switched, at least one of the following torque control measures is taken: torque migration, slope limitation, auxiliary speed and torque regulation; If it is determined that the gear switching process is currently in progress, at least one of the following torque control measures is adopted according to different gear control stages: four-gear torque processing, auxiliary speed regulation and torque reduction, and process protection torque reduction; wherein the gear control stage is divided into an oil filling torque alternation stage, a speed synchronization stage, and a recovery stage; If it is determined that the vehicle is currently in steady-state operation, then after determining that the accelerator pedal opening meets the established stability threshold and there is no wheel-end torque switching demand, only the torque slope limiting measure is adopted; after determining that there is a positive and negative wheel-end torque switching demand, at least one of the following torque control measures is adopted: zero-crossing control, torque slope limiting.

3. The method for dynamic torque control of a hybrid vehicle according to claim 2, characterized in that: The torque slope limiting method includes: Read the maximum allowable rising and / or falling torque slope, and filter it according to the predetermined gradient according to the current target demand torque to obtain the intermediate target demand torque; Perform first-order inertia filtering on the intermediate target demand torque to obtain the final target demand torque.

4. The method for dynamic torque control of a hybrid vehicle according to any one of claims 1 to 3, characterized in that: The control of battery energy includes: Read the maximum allowed long-time charge and discharge power limit and short-time charge and discharge power limit in real time; Real-time calculation of the maximum allowable charge and discharge power value of the power battery under the current working conditions; When the maximum charge and discharge power value rises to the preset value before the short-time charge and discharge power limit value, the maximum power timing function is started; if the timing exceeds the predetermined time threshold, the maximum allowable charge and discharge power value is smoothly transitioned to the long-time discharge power limit value; When the maximum charge and discharge power value drops below the long-term charge and discharge power limit value and exceeds the predetermined cumulative time, the maximum allowable charge and discharge power value is smoothly restored to the short-term discharge power limit value.

5. The method for dynamic torque control of a hybrid vehicle according to claim 4, characterized in that: The control method further comprises: When the vehicle is in a driving state, the driving power is preferentially allocated to the first motor; Among them, the driving power limit value of the first motor is the maximum allowable discharge power value of the battery + the power generated by the second motor - the power of the vehicle accessories; The driving power limit value of the second motor is the maximum allowable discharge power value of the battery - the current driving power of the first motor - the power of the vehicle accessories.

6. The method for dynamic torque control of a hybrid vehicle according to claim 4, characterized in that: The control method further comprises: When the vehicle is in an energy recovery power generation state, the power generation power is preferentially allocated to the second motor; The power limit of the second motor is the maximum allowable charging power of the battery + the power of the vehicle accessories. The power generation limit value of the first motor is the maximum allowable discharge power value of the battery - the current power generation power of the second motor - the power of the vehicle accessories.

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