Hybrid vehicle torque dynamic control method

Abstract

This invention discloses a dynamic torque control method for hybrid vehicles, relating to the field of hybrid vehicle technology. The main design concept of this invention is that, for the drive architecture and control mode of hybrid vehicles, after receiving the torque demanded by the driver, different dynamic torque coordination and distribution control strategies are adopted for three different operating conditions: mode switching, gear switching, and steady-state operation. This dynamically coordinates the torque distribution of the engine, generator, and drive motor, and executes corresponding torque control according to the distribution result, so that the whole vehicle has an excellent driving experience.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hybrid electric vehicles, in particular to a torque dynamic control method for a hybrid electric vehicle. BACKGROUND

[0002] The target hybrid power system is a P2.5+P4 hybrid scheme, and the power transmission system is composed of an engine, a 4DHT (a hybrid special transmission box containing a P2.5 motor), and a rear axle electric drive assembly (containing a P4 motor). The 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 at different vehicle speeds; and the rear axle electric drive assembly can work relatively independently.

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

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

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

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

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

[0008] The present application provides a torque dynamic control method for a hybrid electric vehicle, which comprises:

[0009] After receiving the target demand torque, the current working condition is determined;

[0010] dynamically coordinating the distribution of the torque according to different current working conditions, the current working conditions including: in a driving mode switching process, in a gear shifting process, and in a steady state operation;

[0011] controlling the battery energy while dynamically coordinating the distribution of the torque;

[0012] after arbitrating the torque distribution result, performing corresponding torque control.

[0013] In at least one possible implementation manner, the dynamically coordinating the distribution of the torque according to different current working conditions includes:

[0014] if it is determined that the current is in the driving mode switching process, at least one of the following torque control measures is taken: torque migration, slope limitation, auxiliary speed regulation and torque adjustment;

[0015] if it is determined that the current is in the gear shifting process, according to different gear control stages, at least one of the following torque control measures is taken: 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 current is in the steady state operation, after determining that the accelerator pedal opening degree meets a predetermined stable threshold and there is no wheel end torque switching demand, only the torque slope limitation 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 taken: zero crossing control, torque slope limitation.

[0017] In at least one possible implementation manner, the torque slope limitation includes:

[0018] reading a maximum allowed rising and / or falling torque slope, and filtering according to a current target demand torque at a predetermined gradient to obtain an intermediate target demand torque;

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

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

[0021] reading a maximum allowed long-time charging and discharging power limit value and a short-time charging and discharging power limit value in real time;

[0022] calculating a maximum allowed charging and discharging power value of the power battery in a current working condition in real time;

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

[0024] When the maximum charging and discharging power value decreases to below the long-time charging and discharging power limit value and exceeds a predetermined cumulative time, the maximum allowable charging and discharging power value is smoothly restored to the short-time discharging power limit value.

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

[0026] When the vehicle is in a driving working condition, the first motor is preferentially assigned with driving power;

[0027] The driving power limit value of the first motor is the maximum allowable discharging power value of the battery + the power generation power of the second motor - the power of vehicle accessories.

[0028] The driving power limit value of the second motor is the maximum allowable discharging power value of the battery - the current driving power of the first motor - the power of 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 working condition, the second motor is preferentially assigned with power generation power;

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

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

[0033] Compared with the prior art, the main design concept of the present application is that, for the driving architecture and control mode of a hybrid vehicle, after receiving the driver demand torque, different dynamic torque coordination and distribution control strategies are adopted for mode switching, gear switching, and stable state running in three different working conditions, to dynamically coordinate the torque distribution of the engine, generator, and driving motor, and to execute corresponding torque control according to the distribution result, so that the vehicle has excellent driving experience. BRIEF DESCRIPTION OF DRAWINGS

[0034] To make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described below with reference to the drawings, in which:

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

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

[0037] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numbers represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.

[0038] An embodiment of a torque dynamic control method for a hybrid vehicle is provided by the present application, specifically as shown in Figure 1 , which includes:

[0039] Step S1, after receiving the target demand torque, determining the current working condition;

[0040] Step S2, dynamically coordinating and distributing torque according to different current working conditions, the current working conditions including: running mode switching, gear shifting, and steady state running;

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

[0042] Step S4, after arbitrating the torque distribution result, executing the corresponding torque control.

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

[0044] (1) running mode switching in progress;

[0045] (2) gear shifting in progress;

[0046] (3) steady state running (no mode switching and gear shifting).

[0047] After processing the demand torque, if it is determined that the current is in the driving mode switching process, there are three dynamic torque control measures: torque migration, slope limitation, auxiliary speed regulation and torque adjustment.

[0048] If it is determined that it is in the gear shifting process, then according to different gear control stages, three dynamic torque control measures are selected: 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 control).

[0049] In steady state operation, if the accelerator pedal is stable (quantitative determination can be made by accelerator pedal opening value) and there is no positive or negative wheel end torque switching requirement, only the torque slope protection function, that is, the torque slope limiting measure. If there is tipin and tip out operation and positive and negative wheel end torque switching is triggered, there are zero crossing control measures (a control strategy for suppressing motor jitter near zero torque) and preset slope limiting measures (a gradient control of torque response allowed by the engine or motor during torque adjustment, which is limited by the characteristics of the engine or motor), which are used to improve the driving quality during positive and negative wheel end torque switching.

[0050] It can also be expanded that in the above 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 filtering and slope limiting of the wheel end torque as a whole has been completed in the VCU, and the HTCU only performs the aforementioned zero crossing control and does not perform secondary limiting on the torque instruction of the VCU. When the HTCU detects that the driver 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 started. In the zero crossing control area, the power source torque will be subject to segmented torque slope limiting to buffer the positive and negative meshing gap impact of the transmission chain.

[0052] After the HTCU distributes the wheel end torque to EM1, EM2 and ENG according to the aforementioned torque distribution strategy, the torque slope of the three power sources will be limited and transition smoothing limiting can be used. The mode switching working conditions mentioned in the foregoing can also involve transition smoothing limiting to prevent situations such as impact caused by too fast torque change, power source overload, and power source torque response lagging behind. In other words, based on the whole vehicle dynamic torque distribution and coordination control, the whole vehicle torque is stably and smoothly exerted.

[0053] Here is a way to limit the torque slope, read the maximum allowed rising / descending torque slope, and filter according to the current target demand torque at a certain gradient to obtain an intermediate target demand torque. First-order inertia filtering is performed on the intermediate target demand torque to obtain the final target demand torque.

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

[0055] The HTCU reads the maximum allowed long-time charging and discharging power limit value and the short-time charging and discharging power limit value from the BMS in real time, and the HTCU enables the short-time charging and discharging limit power by default. For example, the current short-time charging and discharging power is the 10s charging and discharging power, which can be understood as the maximum allowed charging and discharging power of the battery with a time limit; the aforementioned long-time charging and discharging power is the power that the power battery can sustainably charge and discharge, and the above short-time and long-time charging and discharging power can be calibrated in different situations after the battery BMS is developed and tested to obtain a Map table / graph.

[0056] The TCU calculates the maximum allowed charging and discharging power value currently used by the power battery in real time, and when the maximum charging and discharging power value approaches the short-time charging and discharging power limit value, the maximum power timing function is started, and once the timing exceeds the allowed time threshold, the maximum allowed charging and discharging power value is smoothly transitioned to the long-time discharging power limit value.

[0057] When the maximum charging and discharging power value currently used is reduced to below the long-time charging and discharging power limit value and exceeds the established cumulative time, the maximum allowed charging and discharging power value is smoothly restored to the short-time discharging power limit value.

[0058] Based on the above energy management concept, in combination with Figure 2 The application also proposes the following power distribution strategy for implementation reference:

[0059] In the driving working condition, the system will preferentially allocate driving power to the EM1 motor: that is, the driving power of the EM1 motor is the maximum allowed discharging power of the battery + the power generated by the GCU - the accessory power as the driving power limit value thereof; and the EM2 motor is limited by the maximum allowed discharging power of the battery - the current driving power of the EM1 motor - the accessory power.

[0060] Here, it is described that the maximum allowed driving power limit value of the system is obtained when two motors are driven, that is, the driving power of the EM1 motor is the maximum discharging power of the battery and the power generated by the EM2 motor minus the accessory power (the power consumed by the vehicle electrical devices is derived from the battery or the power generated by the EM2 motor); and the maximum allowed driving power of the EM2 motor is the maximum discharging power of the battery - the driving power of the EM1 motor - the accessory power, as the limit value of the maximum allowed driving power of the EM2 motor, and the vehicle preferentially drives the EM1 motor.

[0061] In the energy recovery power generation working condition, the system will preferentially allocate power generation power to the EM2 motor: that is, the power generation power of the EM2 motor is the maximum allowed charging power of the battery + the accessory power as the limit value thereof; and in this working condition, the EM1 motor is limited by the maximum discharging power of the battery - the current power generation power of the EM2 motor - the accessory power.

[0062] In addition to the foregoing further power distribution by working condition, it can be supplemented that, in the driving or power generation working condition, there is a power safety factor to prevent short-term charging and discharging power from being too large due to inaccurate values or transient transition values of battery, motor, accessory power (or speed, torque, voltage, electric quantity, etc.) during charging and discharging. The EM1 motor and the EM2 motor are limited by their respective peak powers. Here, the factors affecting the motor capacity are supplemented. In different temperatures and different battery capacities, the allowable charging and discharging power of the battery is limited. These limitations are determined by the BMS battery characteristics. Based on the battery charging and discharging capacity, the vehicle limits the driving and power generation working conditions of the motor. Finally, the maximum driving power and the maximum power generation power of the EM1 motor and the EM2 motor can be obtained.

[0063] In summary, the main design concept of the application is that, for the driving architecture and control mode of the hybrid vehicle, after receiving the driver demand torque, different dynamic torque coordination and distribution control strategies are adopted for the three different working condition states of mode switching, gear shifting and steady state running, to dynamically coordinate the torque distribution of the engine, generator and drive motor, and to execute corresponding torque control according to the distribution results, so that the vehicle has excellent driving experience.

[0064] In the embodiments of the application, if the expression of the position is mentioned, it is based on the relative concept of the embodiments. In addition, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one of the following" and similar expressions mean any combination of these items, including any combination of single or multiple items. For example, at least one of a, b and c can mean a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b and c can be single or multiple.

[0065] The above embodiments according to the drawings illustrate the structure, features and effects of the application, but the above is only a preferred embodiment of the application. It should be noted that the technical features involved in the above embodiments and preferred modes can be reasonably combined and matched into various equivalent schemes by those skilled in the art without departing from or changing the design idea and technical effects of the application. Therefore, the application is not limited by the drawings shown in the drawings. Any change or modification made according to the idea of the application or the equivalent embodiment within the scope of the specification and drawings is still within the protection scope of the application.

Claims

1. A torque dynamic control method for a hybrid vehicle, characterized by, The control method comprises the following steps: After receiving the target demand torque, determine the current working condition; According to different current working conditions, dynamically coordinate and allocate torque, the current working conditions including: driving mode switching, gear shifting and steady state operation; wherein, according to different current working conditions, dynamically coordinating and allocating torque includes: if it is determined that the current is in the driving mode switching process, at least one of the following torque control measures is taken: torque migration, slope limitation, auxiliary speed regulation and torque regulation; if it is determined that the current is in the gear shifting process, at least one of the following torque control measures is taken 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 oil filling torque alternation stage, speed synchronization stage and recovery stage; if it is determined that the current is in the steady state operation, only the torque slope limitation measure is used after it is determined that the throttle opening degree meets the established stable threshold value and there is no wheel end torque switching demand; if it is determined that there is positive and negative wheel end torque switching demand, at least one of the following torque control measures is taken: zero crossing control and torque slope limitation; At the same time of dynamically coordinating and allocating torque, the battery energy is controlled; After arbitrating the torque allocation result, the corresponding torque control is executed.

2. The hybrid vehicle torque dynamic control method according to claim 1, characterized by, The torque slope limitation mode comprises: Reading the maximum allowed rising and / or falling torque slope, and filtering according to the current target demand torque to obtain an intermediate target demand torque at a predetermined gradient; First-order inertia filtering is performed on the intermediate target demand torque to obtain the final target demand torque.

3. The torque dynamic control method of a hybrid vehicle according to claim 1 or 2, characterized by, The battery energy control comprises: Real-time reading of the maximum allowed long-time charging and discharging power limit value and the short-time charging and discharging power limit value; Real-time calculation of the maximum allowed charging and discharging power value of the power battery under the current working condition; When the maximum charging and discharging power value rises to a preset value before the short-time charging and discharging power limit value, start the maximum power timing function; if the timing exceeds the established time threshold, make the maximum allowed charging and discharging power value smoothly transition to the long-time discharging power limit value; When the maximum charging and discharging power value decreases to below the long-time charging and discharging power limit value and exceeds the established cumulative time, make the maximum allowed charging and discharging power value smoothly recover to the short-time discharging power limit value.

4. The hybrid vehicle torque dynamic control method according to claim 3, characterized by, The control method further comprises: When the vehicle is in the driving working condition, preferentially allocate driving power to the first motor; Wherein, the driving power limit value of the first motor is the maximum allowed discharging power value of the battery + the power generation power of the second motor - the accessory power of the whole vehicle; The driving power limit value of the second motor is the maximum allowed discharging power value of the battery - the current driving power of the first motor - the accessory power of the whole vehicle.

5. The hybrid vehicle torque dynamic control method according to claim 3, characterized by, The control method further comprises: When the vehicle is in the energy recovery power generation working condition, preferentially allocate power generation power to the second motor; Wherein, the power generation power limit value of the second motor is the maximum allowed charging power value of the battery + the accessory power of the whole vehicle; The power generation power limit value of the first motor is the maximum allowed discharging power value of the battery - the current power generation power of the second motor - the accessory power of the whole vehicle.

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