A torque safety control method for a power split hybrid system

Abstract

The present invention discloses a power-split hybrid power system. The control unit includes three layers of control modules, namely a bottom layer module, an intermediate layer module, and an upper layer module. The bottom layer module provides a hardware environment for redundant verification for the intermediate layer module and the upper layer module. The intermediate layer module is a torque monitoring module that monitors the torque calculation logic of the application layer and the actual torque response of components. The upper layer module is a torque prediction and torque limitation module that comprehensively considers the driver's operation and the states of each sub-component to provide the uppermost limit and protection for torque safety. The present invention can reduce the risk of transmission torque failure, avoid the occurrence of unexpected vehicle acceleration and deceleration, thereby ensuring the life safety of drivers and passengers, meet the requirements of high-level functional safety, and improve the safety of transmission torque.

Description

Technical Field

[0001] The present invention belongs to the technical field of safety control of hybrid power systems. More specifically, the present invention relates to a power-split hybrid power system. The present invention also relates to a torque safety control method for the power hybrid power system. Background Art

[0002] Torque safety is directly related to the driving safety of a vehicle and involves the life safety of consumers. In recent years, due to torque safety problems caused by system failures, more and more attention has been paid by automobile manufacturers and component suppliers. On the other hand, as an energy-saving vehicle solution with high cost performance of fuel saving rate, power-split hybrid power has attracted more and more attention in the market. Different from the traditional parallel hybrid power system, the power-split hybrid power has its own particularity in the torque safety control method. Therefore, the power-split hybrid power system needs to consider the serious consequences brought by torque safety problems. There is no corresponding solution in the prior art. Summary of the Invention

[0003] The present invention provides a power-split hybrid power system, and its purpose is to improve the safety performance of the transmission torque of the power-split hybrid power system.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] The power-split hybrid power system of the present invention includes an engine, a drive motor, and a generator; the control unit of the hybrid power system includes three layers of control modules, namely a bottom layer module, an intermediate layer module, and an upper layer module; the bottom layer module provides a hardware environment for redundant verification for the intermediate layer module and the upper layer module; the intermediate layer module is a torque monitoring module that monitors the torque calculation logic of the application layer and the actual torque response of components; the upper layer module is a torque prediction and torque limitation module that comprehensively considers driver operations and the states of each sub-component to provide the uppermost limit and protection for torque safety.

[0006] The output shaft of the engine is connected to the outer gear ring of the planetary gear train; the main shaft of the generator is connected to the sun gear of the planetary gear train; the planetary gear of the planetary gear train is used as an output, and is connected to the drive motor output gear on the main shaft of the main drive motor through the planetary gear follower gear; the planetary gear follower gear is coaxially connected to the main drive gear of the main reducer; the main drive gear of the main reducer meshes with the main drive gear of the differential, and the torque is output to the wheel end through the differential.

[0007] The bottom layer module includes a main control chip that supports the dual-core CPU lockstep technology and a system basic chip that supports watchdog and hardware monitoring functions.

[0008] The master chips in the middle layer module and the upper layer module respectively form two independent computing cores, namely Core 1 and Core 2, which constitute a computing and comparison unit; both Core 1 and Core 2 respectively include a middle layer module and an upper layer module.

[0009] The torque monitoring algorithm of the middle layer module mainly includes: torque capacity monitoring, sum of torques monitoring, and torque output monitoring.

[0010] The torque prediction algorithm of the upper layer module comprehensively considers limiting factors including the battery, short-term and long-term characteristics of the motor, and DC / DC load; the torque limit logic of the upper layer module comprehensively considers the characteristics of component voltage, current, and temperature.

[0011] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a torque safety control method for the power split hybrid system described above. The technical solution is as follows:

[0012] When unreasonable deviations occur in the calculation results of the two mutually independent cores 1 and 2 of the main chip, the torque output of the transmission system is shut down; when a hardware error or system crash occurs in the main control chip, the system basic chip can restart the hardware environment of cores 1 and 2.

[0013] The middle layer module monitors the actual torque fed back by the power source component in real time; estimates the torque of the power source component in real time according to the rotational speed, angular acceleration, and moment of inertia information of the system rotating components; if the deviation between the torque estimated by the algorithm and the actual torque fed back by the component is large, the system actively reduces the torque or shuts down the relevant power source to ensure entering a safe state.

[0014] The present invention adopts the above technical solution, adopts a three-layer torque safety control scheme, mutually verifies and restricts each other to improve the torque safety of the transmission system; the middle layer adopts torque monitoring logic, which is different from the traditional parallel hybrid control scheme, and is derived according to a specific mechanical structure, and is applicable to the power split hybrid system of the planetary gear scheme; the middle layer adopts torque monitoring logic, estimates the actual output torque of the engine according to a specific mechanical structure and mathematical relationship, and verifies it with the actual torque fed back by the engine controller to further ensure torque safety; when the torque monitoring in the middle layer detects a torque fault, the output of the upper layer torque limit module is restricted, and the transmission system actively reduces the torque to ensure driving safety. Brief Description of the Drawings

[0015] The content shown in the drawings and the marks in the figures are briefly described as follows:

[0016] Figure 1 It is a schematic structural diagram of a transmission device applicable to the present invention;

[0017] Figure 2Schematic diagram of the control system structure of the present invention;

[0018] Figure 3 Torque monitoring architecture diagram of the middle layer of the present invention;

[0019] Figure 4 Schematic diagram of the monitoring logic for the sum of torques of the present invention;

[0020] Figure 5 Torque limit architecture diagram of the upper layer of the present invention.

[0021] Figure 1 The markings in [] are:

[0022] 1. Sun gear, 2. Planet carrier, 3. Ring gear, 4. Planet carrier drive gear, 5. Planet carrier driven gear, 6. Drive motor output gear, 7. Main reducer drive gear, 8. Differential, 9. Main reducer driven gear, 10. One-way clutch, 11. Planet gear, 12. Engine, 13. Generator (EM1), 14. Drive motor (EM2). Detailed implementation manners

[0023] The following is a further detailed description of the specific implementation manners of the present invention by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art have a more complete, accurate and in-depth understanding of the technical concept and technical solution of the present invention.

[0024] The power-split hybrid system of the present invention includes hardware that meets certain technical indicators and control software with rigorous logic.

[0025] 1. Application of the planetary gear type power-split hybrid system of the present invention:

[0026] The torque safety control method of the present invention is applicable to the planetary gear type power-split hybrid scheme, such as Figure 1 shown in the structure of this transmission system, including engine 12, drive motor 14, and generator 13;

[0027] As shown in Figure 1 : The engine 12 is connected to the ring gear 3 of the single planetary gear 11, and the generator 13 (EM1) is connected to the sun gear 1 of the single planetary gear train; in the planetary gear train, the planet carrier drive gear 4 on the planet carrier 2 is used as the output and is connected to the main drive motor 14 (EM2), and the output torque reaches the wheel end. The output shaft of the engine 12 is connected to the central shaft of the ring gear 3 of the planetary gear train through a one-way clutch 10 to realize the connection and separation of the two shafts.

[0028] Specifically as follows:

[0029] The output shaft of the described engine 12 is connected to the outer gear ring 3 of the planetary gear train; the main shaft of the described generator 13 is connected to the sun gear 1 of the planetary gear train; the planetary carrier driving gear 4 in the planetary gear train serves as the output and is connected to the driving motor output gear 6 on the main shaft of the main drive motor 14 through the planetary carrier driven gear 5; the planetary carrier driven gear 5 is coaxially connected to the main reducer driving gear 7; the main reducer driving gear 7 meshes with the main reducer driven gear 9 on the differential 8, and torque is output to the wheel end through the differential 8.

[0030] 2. The core technology reflecting the creativity of the present invention:

[0031] In order to solve the problems of the prior art and achieve the invention purpose of improving the safety performance of the transmission torque of the power split hybrid system, the core technical solution adopted by the present invention is:

[0032] As Figure 2 shown, the control unit of the power split hybrid system of the present invention includes three layers of control modules, namely the bottom layer module, the middle layer module, and the upper layer module;

[0033] This control technical solution mainly includes: a dual-core CPU hardware controller at the bottom layer, a torque monitoring algorithm at the middle layer, and a torque prediction and torque limitation module at the upper layer.

[0034] Specifically:

[0035] The described bottom layer module provides a hardware environment for redundant verification for the middle layer module and the upper layer module; the described middle layer module is a torque monitoring module that monitors the torque calculation logic of the application layer and the actual torque response of components; the described upper layer module is a torque prediction and torque limitation module that comprehensively considers the driver's operation and the states of each sub-component, and provides the uppermost layer of limitation and protection for torque safety.

[0036] The torque safety control technical solution of the present invention can reduce the risk of transmission torque failure, avoid the occurrence of unexpected vehicle acceleration and deceleration, thereby ensuring the life safety of drivers and passengers; meet the requirements of high-level functional safety, and improve the safety of transmission torque; this control technical solution is applicable to planetary gear type transmission mechanisms, and rigorously considers the structural characteristics of the power split scheme itself and the particularity of the torque distribution algorithm; this control technical solution is divided into three layers of safety monitoring, and the layers cooperate closely with each other to jointly ensure torque safety. The three-layer torque safety control scheme has functions such as redundant verification, failure detection, and fault response, effectively improving the torque safety of the power split hybrid system.

[0037] 3. Regarding the bottom layer module:

[0038] The hardware controller of the underlying module includes a main control chip that supports the dual-core CPU lockstep technology and a system base chip that supports watchdog and hardware monitoring functions.

[0039] The underlying module provides a redundant verification hardware environment for the middle layer module and the upper layer module, mainly responsible for hardware-level monitoring, and executing the hardware monitoring and dual-core logic verification functions of the main control chip.

[0040] The system base chip supplies power to the main control chip and provides functions such as watchdog, voltage, and clock detection. When faults such as the torque control logic of the main control chip running away or deadlocking occur, the system base chip triggers the reset of the main control chip. If errors such as the main control chip being locked up, logic running away, or dual-core verification not passing occur, the system base chip can quickly reset to ensure the safety of torque control.

[0041] For the technical requirements of the system base chip, it is necessary to select a high-security-level chip that includes functions such as watchdog, overvoltage and overcurrent detection, and hardware runaway diagnosis.

[0042] 4. Regarding the dual cores composed of the middle layer module and the upper layer module:

[0043] The main control chips in the middle layer module and the upper layer module respectively form two independent arithmetic cores, namely Core 1 and Core 2, which form an arithmetic comparison unit; both Core 1 and Core 2 respectively include a middle layer module and an upper layer module. The software logic in Core 1 includes the upper layer module and the middle layer module, and Core 2 is a redundant verification core, and its internal execution logic is exactly the same as that of Core 1.

[0044] When unreasonable deviations occur in the calculation results of the two mutually independent cores, Core 1 and Core 2, of the main chip, the torque output of the drive system is shut off. When a hardware error or crash occurs in the main control chip, the system base chip can restart the hardware environment of Core 1 and Core 2.

[0045] In the middle layer module and the upper layer module, the upper limit module is restricted by the middle layer monitoring module; when the monitoring module detects a torque fault, the output of the upper layer module is restricted to assist the power system to actively reduce torque.

[0046] In the lockstep control mode, the inputs related to torque control are sent to these two cores, and then these two cores run the same calculation logic within similar clock cycles, regularly compare the calculation results, and detect whether a fault occurs.

[0047] If the operation results of the two cores do not match or show a large deviation, it is marked as a torque safety error and the torque output of the power source is shut off. If the operation results of Core 1 and Core 2 deviate greatly, the main control chip hardware shuts off the torque output and the vehicle enters a safe state.

[0048] For the technical requirements of the main control chip, a control chip that supports dual-core lockstep operation needs to be selected.

[0049] For the upper-layer module and the middle-layer module in Core 1, the middle-layer module is responsible for torque safety monitoring. When the middle-layer module detects a torque error, it will report the error information to the upper-layer module. When the upper-layer module receives the error information (Torqueerror), it enters the fault handling mode of the upper-layer module.

[0050] When the power-split hybrid system is in torque control mode, the transmission torque calculated by the system is restricted and constrained by the upper-layer module; when the torque monitoring logic detects that the actual torque response of the component is inconsistent with the torque demand, there is a relatively serious risk of torque runaway in the system. At this time, on the one hand, the system shuts off the torque output through the middle-layer module, and on the other hand, restricts the calculation of the demand torque through the upper-layer module. The upper-layer module and the middle-layer module cooperate closely to ensure that the system enters a safe state by means of torque shutdown or torque reduction.

[0051] 5. Regarding the middle-layer module:

[0052] As Figure 3 shown, it is the torque monitoring architecture diagram of the middle-layer module of the present invention.

[0053] The torque monitoring algorithm of the middle-layer module mainly includes: torque capacity monitoring, sum of torques monitoring, torque output monitoring, and Error handling module (error handling).

[0054] Different from traditional parallel hybrids, the torque capacity and the sum of torques of power-split hybrids are derived based on the specific physical structure and mathematical relationships of the power-split system, rather than being directly superimposed.

[0055] Among them, torque capacity monitoring mainly calculates the upper limit of the demand torque in the driving state, the upper limit of the demand torque in the braking state, and the coordination of the torque capacity.

[0056] The middle-layer monitoring module not only monitors the actual torque fed back by the power source component in real time, but also estimates the torque of the power source component in real time based on information such as the rotational speed, angular acceleration, and moment of inertia of the rotating components of the system. If the deviation between the torque estimated by the algorithm and the actual torque fed back by the component is large, the system actively reduces the torque or shuts down the relevant power source to ensure entering a safe state.

[0057] In any case, the driver's demand torque and the torque output of the component cannot exceed the torque capacity limit of the driveline.

[0058] The minimum of the maximum allowable demand torque signal (Torque max) output by the torque capacity monitoring module and the driver demand torque signal (Torque command) calculated by the logic layer is used as the input signal for other torque monitoring modules.

[0059] Furthermore, after the torque capacity monitoring logic, the sum-of-torques monitoring logic needs to be executed. The sum-of-torques monitoring logic includes: actual sum torque calculation, engine torque estimation, and torque comparison logic.

[0060] The torque capacity monitoring calculates the upper limits of the wheel-end drive and braking torques to ensure that the driver demand torque is within the limit values in any case.

[0061] The sum-of-torques monitoring mainly includes two parts: First, obtain the actual power source output torque through the CAN network, and judge whether the actual torque of the components meets the driver's demand according to certain calculation logics and mathematical relationships; Second, estimate the torque of the power source components in real time based on information such as the rotational speed, angular acceleration, and moment of inertia of the rotating components of the transmission device.

[0062] If the deviation between the torque estimated by the algorithm and the actual torque feedback by the components is large, the system will actively reduce the torque or turn off the relevant power source to ensure entering a safe state.

[0063] 6. Regarding the upper-layer module:

[0064] The upper-layer module mainly includes: a torque prediction algorithm considering the long-term and short-term characteristics of the battery and the motor, and a torque limit module based on the current state of the battery and the motor.

[0065] The torque prediction algorithm of the upper-layer module comprehensively considers the limiting factors including the long-term and short-term characteristics of the battery and the motor, and the DC / DC load; the torque limit logic of the upper-layer module comprehensively considers the characteristics of the voltage, current, and temperature of the components.

[0066] The upper-layer torque prediction and torque limit module, comprehensively considering the driver's operation and the states of each sub-component, provides the uppermost limit and protection for torque safety. The torque limit module comprehensively considers the driver's operation behavior and the actual operating state of the components. It can not only prevent overheating, overcurrent, overcharging, etc. of the components, but also ensure the torque safety of the transmission system. For example, when the driver has a braking operation, the available positive torque of the main drive motor is limited; during braking, the appearance of unexpected positive torque is avoided. When the intermediate-layer torque monitoring module detects a serious torque failure fault, the torque limit module will immediately limit the available torque to a very small value to prevent the deterioration of the consequences of torque failure.

[0067] The motor controller uploads the long-term predicted torque and the short-term predicted torque. This module calculates the available long-term and short-term torque limits of the dual-motor system based on the DC / DC load power request and a certain system margin. On the premise of ensuring the torque safety of the power source components and the whole vehicle, the optimal economy and power performance of the whole vehicle are achieved.

[0068] 7. Torque safety control method of the present invention:

[0069] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a torque safety control method for the power-split hybrid power system described above. The technical solution is:

[0070] When unreasonable deviations occur in the calculation results of the two independent cores 1 and 2 of the main chip, the torque output of the drive system is shut down; when a hardware error or crash occurs in the main control chip, the system base chip can restart the hardware environment of cores 1 and 2.

[0071] The intermediate layer module monitors the actual torque fed back by the power source components in real time; estimates the torque of the power source components in real time according to the information of the rotational speed, angular acceleration, and moment of inertia of the system rotating components; if the deviation between the torque estimated by the algorithm and the actual torque fed back by the components is large, the system actively reduces the torque or shuts down the relevant power source to ensure entering a safe state.

[0072] 8. Torque sum monitoring logic of the present invention:

[0073] As Figure 4 shown, it is a schematic diagram of the torque sum monitoring logic of the present invention. For the actual torque superposition calculation module (Actual sum torque), it is verified based on the following dynamic formula:

[0074] T Wheel = Trq(Acc, Brk, V)

[0075]

[0076]

[0077]

[0078] T S :T R :T C = 1:i:-(i + 1)

[0079]

[0080] Where:

[0081] T wheelIt is the required torque calculated by the Pedal Map by looking up the table according to the vehicle speed and the travel of the accelerator pedal and the brake pedal, and it is a known quantity;

[0082] T Eng 、T EM1 and T EM2 respectively represent the actual output torques of the engine, the EM1 motor, and the EM2 motor;

[0083] T R 、T S and T C respectively represent the acting torques on the ring gear, the sun gear, and the planet carrier;

[0084] J eng 、J S and J C respectively represent the equivalent moments of inertia of the ring gear, the sun gear, and the planet carrier;

[0085] ω R 、ω S 、ω C and ω Wheel respectively represent the angular velocities of the ring gear, the sun gear, the planet carrier, and the wheel;

[0086] i is the transmission ratio of a single planetary gear set, K1 represents the transmission ratio from the output end of the EM2 motor to the wheel end, and K2 represents the transmission ratio from the output end of the planet carrier to the wheel end;

[0087] According to the above dynamic formulas, by eliminating the intermediate variables, the mathematical relationship between the required torque at the wheel end and the actual output torques of the three power sources can be obtained. Through the determined mathematical equation, the monitoring of the actual superimposed torque can be carried out.

[0088] Similarly, since the accuracy of the engine torque model is lower than that of the motor torque model, the actual torque of the engine can be estimated based on the above dynamic formulas and compared with the actual torque uploaded by the engine controller. This method can accurately identify the engine torque error and ensure the driving safety of the vehicle.

[0089] The torque monitoring method based on the kinematic equation of the planetary gear is applicable to Figure 1 the power split hybrid system with this structure. This method can accurately diagnose the torque error of the transmission system and further improve the torque safety.

[0090] 9. The upper torque limit of the present invention:

[0091] Such as Figure 5As shown in the figure, it is the upper-layer torque limit architecture diagram of the present invention. This module mainly includes: long-term torque limit module, short-term torque limit module, DC / DC load power; temperature limit module, voltage and current limit module, and battery SOC limit module; Error handling module.

[0092] Among them, the long-term and short-term torque limit modules need to receive the short-term prediction and long-term prediction torque information sent by the motor controller. This set of signals is calculated based on the temperature rise characteristics of the motor and the battery, which can significantly reduce the torque safety risk caused by the failure of components themselves. The DC / DC load power comes from the DC / DC controller, which can ensure that the electrical load power demand of the whole vehicle is met on the premise of ensuring torque safety.

[0093] Furthermore, the calculated long-term and short-term prediction limit values are further restricted by the states of components such as voltage and temperature. Here, it is subdivided into temperature limit, long-term and short-term limit, and battery SOC limit values. If no torque error occurs, the output of this module will ultimately affect the calculation and distribution of transmission torque.

[0094] If the middle-layer torque monitoring module detects torque error information, it will report it to the upper-layer torque limit module. In the Error handling module, corresponding handling measures will be implemented according to the torque fault information, such as shutting down the torque output or reducing the transmission system output torque.

[0095] 10. Compared with the prior art, the present invention has the following advantages:

[0096] (1). For the power-split hybrid system, the three-layer torque safety control method cross-checks and restricts each other, improving the torque safety of the transmission system.

[0097] (2). The middle-layer torque monitoring logic is different from the traditional parallel hybrid control scheme. It is deduced based on a specific mechanical structure and is applicable to the power-split hybrid system with a planetary gear scheme.

[0098] (3). The middle-layer torque monitoring logic estimates the actual output torque of the engine based on a specific mechanical structure and mathematical relationship, and checks it with the actual torque fed back by the engine controller to further ensure torque safety.

[0099] (4). When the middle-layer torque monitoring detects a torque fault, the output of the upper-layer torque limit module is restricted, and the transmission system actively reduces torque to ensure driving safety.

[0100] The present invention has been described exemplarily in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A power-split hybrid system, the hybrid system comprising an engine (12), a drive motor (14), and a generator (13); Characterized in that: The control unit of the hybrid system includes three layers of control modules, namely a bottom layer module, a middle layer module, and an upper layer module; the bottom layer module provides a hardware environment for redundancy check for the middle layer module and the upper layer module; the middle layer module is a torque monitoring module that monitors the torque calculation logic of the application layer and the actual torque response of components; the upper layer module is a torque prediction and torque limitation module that comprehensively considers driver operations and the states of each sub-component to provide the uppermost limit and protection for torque safety; The output shaft of the engine (12) is connected to the outer gear ring (3) of the planetary gear train; the main shaft of the generator (13) is connected to the sun gear (1) of the planetary gear train; the planetary carrier driving gear (4) in the planetary gear train is used as an output and is connected to the drive motor output gear (6) on the main shaft of the drive motor (14) through the planetary carrier driven gear (5); the planetary carrier driven gear (5) is coaxially connected to the main reducer driving gear (7); the main reducer driving gear (7) meshes with the main reducer driven gear (9) on the differential (8), and torque is output to the wheel end through the differential (8); The bottom layer module includes a main control chip supporting the dual-core CPU lockstep technology and a system basic chip supporting watchdog and hardware monitoring functions; The main control chips in the middle layer module and the upper layer module respectively form two independent operation cores, namely core 1 and core 2, to form an operation comparison unit; both core 1 and core 2 respectively include a middle layer module and an upper layer module; The torque monitoring algorithm of the middle layer module mainly includes: torque capacity monitoring, torque sum monitoring, and torque output monitoring; The torque prediction algorithm of the upper layer module comprehensively considers limiting factors including the battery, the long-term and short-term characteristics of the motor, and the DC / DC load; the torque limitation logic of the upper layer module comprehensively considers the characteristics of the voltage, current, and temperature of components.

2. The torque safety control method for the power-split hybrid system according to claim 1, characterized in that: When unreasonable deviations occur in the calculation results of the two mutually independent cores 1 and 2 of the main chip, the torque output of the drive system is shut down; when a hardware error or a crash occurs in the main control chip, the system basic chip can restart the hardware environment of cores 1 and 2; The middle layer module monitors the actual torque fed back by the power source components in real time; estimates the torque of the power source components in real time according to the information of the rotational speed, angular acceleration, and moment of inertia of the system rotating components; If the deviation between the torque estimated by the algorithm and the actual torque fed back by the components is large, the system actively reduces the torque or shuts down the relevant power source to ensure entering a safe state.

Images