A misfire fault diagnosis method and device for a hybrid power system

Abstract

The application discloses a hybrid power system misfire fault diagnosis method and device, and belongs to the technical field of power system fault diagnosis.The application judges engine misfire based on the AVP value obtained based on instantaneous rotating speed, and optimizes the critical value of the AVP by using a PSO algorithm, so that the misfire state of the engine can be quantified, and the misfire fault of the hybrid power system can be accurately diagnosed; and through torque estimation, the estimated engine torque is continuously compared with the engine demand torque, then the motor torque is corrected, the motor torque assists the engine torque, and thus the whole vehicle torque reaches a balanced state, the advantages of the hybrid power system are fully brought into play, the system can be operated with faults in a fault-tolerant control range, and the application has the characteristics of fast response, strong practicability and good economy.The application is suitable for new energy automobile fields and the like, and the misfire fault of the hybrid power system can be accurately diagnosed through the AVP technology.

Description

Technical Field

[0001] This invention relates to a method and apparatus for diagnosing misfires in a hybrid power system, belonging to the field of power system fault diagnosis technology. Background Technology

[0002] With the increasing prominence of environmental and energy issues, hybrid electric vehicles (HEVs), which have advantages in energy conservation and environmental protection, have seen significant development. However, as a complex electromechanical hybrid system, HEVs have more complex potential failures than traditional vehicles, and they also have high-voltage electrical systems, which impose stricter requirements on their safety.

[0003] Existing automotive fault diagnosis systems are mainly On-Board Diagnostics (OBD), which originated in the United States in the 1980s and is now quite mature. However, current OBD technology is generally designed for the engine control unit and cannot monitor key components such as the electric motor and battery in hybrid systems, thus failing to meet the diagnostic needs of HEV vehicles.

[0004] Torque estimation is a key technology for torque distribution in parallel hybrid electric vehicles (PHEVs) and an important component of PHEV load estimation. Therefore, obtaining a simple, reliable, and highly accurate torque estimate has become a research hotspot. Torque estimation can effectively diagnose misfire faults in hybrid electric systems, demonstrating strong practicality and overcoming the limitations of OBD technology in diagnosing misfire faults in hybrid electric systems. Summary of the Invention

[0005] In view of the fact that existing OBD technology cannot meet the diagnostic needs of HEV vehicles, the main purpose of this invention is to provide a method and device for diagnosing misfire faults in hybrid power systems, which can accurately diagnose misfire faults in hybrid power systems through average power value (AVP) technology.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention discloses a misfire fault diagnosis device for a hybrid power system, comprising four main parts: a host computer (PC), a hybrid powertrain, a vehicle communication unit (VCU), and a working module. The PC and VCU are connected via CAN bus; data from the PC is transmitted to the hybrid powertrain via signal lines; the hybrid powertrain connects to the VCU through sensors for real-time signal transmission and interaction; the working module consists of five modules: a test signal acquisition module, a signal processing module, a fault diagnosis module, a fault-tolerant control module, and a verification module, which work in conjunction with the other three parts to achieve misfire fault diagnosis. The device utilizes the host computer to monitor and collect data and transmit it to the hybrid powertrain, monitoring the state of the hybrid powertrain in real time when a misfire fault occurs.

[0008] The working mode of the module is as follows:

[0009] The signal acquisition module receives signals from the crankshaft signal disk of the hybrid powertrain engine, instantaneous engine speed signal, throttle opening, intake pressure and temperature, and motor signals including motor speed signal and motor voltage signal.

[0010] The fault diagnosis module obtains the engine crankshaft signal disk signal, and in conjunction with the VCU, it downloads a program via CAN from the host PC. Combined with the real-time signals transmitted by the hybrid powertrain, it analyzes the hybrid power operating condition and diagnoses whether the engine has misfired.

[0011] The signal processing module acquires the instantaneous engine speed signal and motor speed signal from the signal processing module under test, performs signal conversion and correction, and obtains the estimated torque, which serves as a preprocessing step for subsequent acquisition of AVP value and motor torque compensation.

[0012] The fault-tolerant control module receives the misfire judgment from the fault diagnosis module and the estimated torque from the signal processing module, transmits it to the hybrid powertrain system, and drives the hybrid powertrain to drive the engine and motor according to the VCU's instructions to perform fault-tolerant control of the hybrid powertrain system.

[0013] The verification module loads the model and data onto a host PC and transmits it to the hybrid powertrain for real-time verification.

[0014] The host computer PC consists of a model building section and a data acquisition and monitoring section. It can connect to the hybrid powertrain and collect data signals in real time through the loaded model and the installed monitoring platform software, thus playing the role of data collection and monitoring.

[0015] The signal transmission between the hybrid powertrain and the VCU is used for misfire diagnosis and fault-tolerant control of the hybrid powertrain.

[0016] This invention discloses a method for diagnosing misfire faults in a hybrid power system, comprising the following steps:

[0017] Step 1: Obtain the instantaneous signal of the vehicle through the signal acquisition module;

[0018] 1.1 The signal acquisition module acquires the analog signal of the original instantaneous rotational speed of the vehicle component;

[0019] 1.2 The obtained original analog signal is converted and calibrated to obtain the relationship between the original analog signal and the original digital signal. The signal is then filtered to obtain the instantaneous speed signal of the vehicle.

[0020] 1.3 Through steps 1.1 and 1.2, obtain the engine crankshaft signal disk signal, throttle opening, intake pressure and temperature, motor speed signal and motor voltage signal.

[0021] Step 2: Using the fault diagnosis module, combined with the VCU, real-time signals and the engine crankshaft signal disk signal obtained in Step 1, the engine misfire status is determined by the AVP value, and the misfire fault of the hybrid power system is accurately diagnosed.

[0022] Set up a misfire fault and use AVP to accurately determine if the engine has misfired.

[0023] Specifically as follows:

[0024]

[0025] The average power value is determined based on the duration of the expansion stroke for each cylinder. The time it takes for the engine crankshaft to rotate 180°. This is the time it takes for the engine crankshaft to rotate 180° next time. During normal engine operation, the AVP value is close to zero; a sudden change in the AVP value indicates a misfire.

[0026] Define a critical threshold (NL) for AVP to distinguish between normal and misfire cycles. Selecting the NL value as 1.5 to 2 times the AVP value during normal operation, as is the conventional method, can slow down fault confirmation time. Optimizing the NL value using the PSO algorithm can optimize the PSO value without misdiagnosis, thus accelerating the diagnostic process.

[0027] Whether to continue updating particles is determined by the variance of the fitness function. The particle's position and velocity are updated according to the following formula:

[0028] v i，j (t+1)=wv i，j (t)+c1r1[p i，j -x i，j (t)]+c2r2[p g，j -x i，j (t)]

[0029] x i，j (t+1)=x i，j (t)+v i，j (t+1), j = 1, 2, ..., d

[0030] In the formula, the position and velocity of the i-th particle in the d-dimensional search space are X and X, respectively. i =(x i，1 x i，2 ... x i，d ) and V i =(v i，1 v i，2 ... v i，d ), where w is the inertia weight, c1 and c2 are learning factors, and r1 and r2 are numbers that follow a uniform distribution between 0 and 1.

[0031] The preset number of particles and iterations are used, and the fitness function is J = ∑|MC|, where M represents the current AVP value and C represents the current threshold. The lower the value of J, the better the threshold selection.

[0032] Define fire detection capability m c :

[0033]

[0034] Where m t It is the total number of fires, n d and n f These represent the number of missed detections and false positives, respectively. (m) c To clarify the fire detection capability of AVP; M is defined. A :

[0035]

[0036] In the formula, n is the number of cylinders in the engine. M A It is the average value of AVP for two engine cycles, used to eliminate AVP deviation and improve misfire detection accuracy.

[0037] The magnitude and accuracy of the AVP value directly determine the accuracy of engine misfire diagnosis.

[0038] AVP c =AVP-M A

[0039] Use compensated AVP c By eliminating misleading AVP bias, the fire detection results are smoothed out.

[0040] Step 3: Using the instantaneous vehicle signal obtained in Step 1, obtain the signed ignition frequency point speed fluctuation amplitude, and perform vehicle torque estimation to prepare for the fault-tolerant control in Step 4.

[0041] The fluctuation characteristics of the instantaneous crankshaft speed are one of the effective indicators reflecting the engine torque. Fourier transform is performed on the instantaneous vehicle speed signal and motor speed signal obtained in step one to obtain the fluctuation amplitude of the instantaneous crankshaft speed and the fluctuation amplitude of the motor torque. Algebraic difference is performed on the instantaneous crankshaft speed fluctuation amplitude to obtain the fluctuation amplitude of the engine at the signed firing frequency point. The difference between the maximum and minimum instantaneous speed values ​​and the fluctuation amplitude of the instantaneous speed at the firing frequency are calibrated and a MAP diagram is made. Torque is then estimated by looking up the MAP during engine operation.

[0042] Using the Map-Aspect Ratio (MAP) method, the correlation between engine torque and motor torque and speed fluctuation amplitude is obtained, showing the relationship between them under steady-state and dynamic conditions. Combining these steady-state and dynamic correlations, torque estimation is performed during actual vehicle operation. Due to intake lag in turbocharged diesel engines during dynamic operation, the accuracy of torque estimation based on steady-state conditions is insufficient, and motor torque compensation is inaccurate. Therefore, torque correction is performed using throttle opening, intake pressure, and temperature signals. Finally, the corrected speed fluctuation amplitude is used for torque estimation.

[0043] The engine torque is on the order of 10 N·m, while the motor torque is on the order of 10 N·m. -4 In hybrid systems, the torque fluctuation of the electric motor is much smaller than that of the engine and the entire vehicle, so the influence of the electric motor's torque fluctuation can be ignored.

[0044] Step 4: The fault-tolerant control module receives the AVP value from Step 2 to determine the misfire and the estimated torque from Step 3, and drives the hybrid power system according to the instructions of the VCU to perform fault-tolerant control of the hybrid power system.

[0045] The fault-tolerant control module addresses the issue of inaccurate misfire torque estimation due to sudden and uneven engine speeds after a misfire. It performs a misfire torque estimation, compares the estimated engine torque with the required engine torque, and then corrects the electric motor torque to assist the engine torque, thus bringing the vehicle to a balanced state. The hybrid system receives the demand for electric motor torque and drives it according to the VCU's instructions, implementing fault-tolerant control based on the engine misfire fault.

[0046] Step 5: Using the verification module, perform fault-tolerant control of the hybrid power system from Step 4.

[0047] The microcontroller is programmed with an AVP calculation program; the instantaneous speed signal is acquired; the microcontroller program processes the instantaneous speed signal to obtain the AVP; the microcontroller program analyzes the AVP and determines whether there is a misfire; and the data signal transmitted by the hybrid powertrain system is verified.

[0048] Beneficial effects

[0049] 1. The present invention discloses a method for diagnosing misfire faults in a hybrid power system. By judging engine misfire based on the AVP value obtained from instantaneous speed, and by optimizing the critical value of AVP using the PSO algorithm, the misfire state of the engine can be quantified and the misfire fault of the hybrid power system can be accurately diagnosed.

[0050] 2. The present invention discloses a method and apparatus for diagnosing misfire faults in a hybrid power system. By estimating the torque, the estimated engine torque is compared with the engine's required torque, and then the motor torque is corrected to assist the engine torque, thereby enabling the vehicle to reach a balanced state. This fully leverages the advantages of the hybrid power system, allowing the system to operate with faults within the fault-tolerant control range. It features fast response, strong practicality, and good economy. Attached Figure Description

[0051] Figure 1 This is a flowchart of the misfire fault diagnosis method for a hybrid power system according to the first embodiment of the present invention;

[0052] Figure 2 This is a flowchart of the PSO algorithm according to the first embodiment of the present invention;

[0053] Figure 3 This is a structural diagram of the verification platform according to the first embodiment of the present invention;

[0054] Figure 4 This is a flowchart of the AVP microcontroller program according to the first embodiment of the present invention. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The technical problems solved by the present invention and its beneficial effects are also described. It should be noted that the described embodiments are only intended to facilitate understanding of the present invention and do not constitute any limitation thereof.

[0056] This embodiment uses a certain type of P2 hybrid electric vehicle as an example. A misfire fault diagnosis system is constructed by comprising a signal acquisition module, a fault diagnosis module, a signal processing module, a fault-tolerant control module, and a verification module. Real-time signals transmitted between these modules are collected, and specific fault diagnoses are performed using the methods disclosed in this invention. The misfire fault diagnosis device of this invention can perform misfire fault diagnosis in hybrid electric systems. It can effectively utilize the advantages of hybrid systems, achieving fault-tolerant control through control algorithms to drive motor torque compensation. Simultaneously, experimental verification demonstrates the accuracy and reliability of the misfire fault diagnosis.

[0057] like Figure 1As shown, this embodiment provides a fault diagnosis method and apparatus for a hybrid power system, achieving the objective based on the combination of the apparatus and the method. The apparatus has four main components: a host computer (PC), a hybrid powertrain, a vehicle control unit (VCU), and a working module. The signal acquisition module obtains signals such as the instantaneous speed signal of the vehicle; the fault diagnosis module, in conjunction with the VCU, analyzes the hybrid power operating condition and diagnoses engine misfire based on the program downloaded to the host computer via CAN, combined with the real-time signals transmitted by the hybrid powertrain and the estimated torque, using the program downloaded to the host computer via CAN; the signal processing module obtains the instantaneous engine speed signal and motor speed signal from the signal acquisition module, performs signal conversion and correction, and obtains the estimated torque; the fault-tolerant control module obtains the fault information and estimated torque, drives the hybrid powertrain system to drive the engine and motor according to the instructions of the VCU, and performs fault-tolerant control of the hybrid powertrain system; the verification module loads the model and data to the hybrid powertrain via the host computer for real-time verification.

[0058] This implementation acquires the vehicle component's driving test signal, and uses the optimized AVP algorithm to determine whether a misfire fault has occurred based on the instantaneous rotational speed. The estimated torque is obtained by converting and correcting the engine crankshaft instantaneous rotational speed signal and the motor rotational speed signal. The fault-tolerant control system receives the misfire fault and the estimated torque, and drives the motor to compensate through the control algorithm to achieve fault-tolerant control.

[0059] The signal acquisition module acquires the raw analog signals of the vehicle components; it performs signal conversion and calibration on the raw analog signals to obtain the relationship between the raw analog signals and the raw digital signals, and performs filtering processing to obtain the instantaneous speed signal of the vehicle. Engine crankshaft signal disk signals, throttle opening, intake pressure and temperature, and motor signals including motor speed signals and motor voltage signals are obtained through similar methods.

[0060] After receiving the signal from the engine crankshaft signal disc, a misfire fault is set, and the average power output (AVP) is used to accurately determine whether the engine has misfired. Details are as follows:

[0061]

[0062] The average power (AVP) value is determined based on the duration of the expansion stroke for each cylinder. The time it takes for the engine crankshaft to rotate 180°. This is the time it takes for the engine crankshaft to rotate 180° next time. During normal engine operation, the AVP value is close to zero; during a misfire, a sudden change in the AVP value indicates that a misfire has occurred.

[0063] A critical threshold (NL) for AVP is defined to distinguish between normal and misfire cycles. The settling time of AVP oscillation is the referroas damping time. Increasing engine load and engine speed leads to a greater amplitude of engine speed deviation. The damping time is inversely proportional to engine load and directly related to engine speed. Damping time plays an important role for diagnostic purposes. The shorter the damping time, the lower the probability of false misfire detection. Damping of post-ignition deviation is faster under high load, making AVP more accurate under high load operation. A misfire event is detected when AVP exceeds the NL threshold (depending on engine speed and load).

[0064] Selecting the NL value as 1.5 to 2 times the AVP value during normal operation, as is the conventional method, will slow down the fault confirmation time. Optimizing the NL value using the PSO algorithm can optimize the PSO value without misjudging, thus speeding up the diagnosis. The algorithm flowchart is as follows: Figure 2 As shown.

[0065] Whether to continue updating particles is determined by the variance of the fitness function. The particle's position and velocity are updated according to the following formula:

[0066] v i，j (t+1)=wv i，j (t)+c1r1[p i，j -x i，j (t)]+c2r2[p g，j -x i，j (t)]

[0067] x i，j (t+1)=x i，j (t)+v i，j (t+1), j = 1, 2, ..., d

[0068] In the formula, the position and velocity of the i-th particle in the d-dimensional search space are X and X, respectively. i =(x i，1 x i，2 ... x i，d ) and V i =(v i，1 v i，2 ... v i，d ), where w is the inertia weight, c1 and c2 are learning factors, and r1 and r2 are numbers that follow a uniform distribution between 0 and 1.

[0069] The number of particles is set to 10, the number of iterations is set to 200, and the fitness function is set to J = ∑|MC|, where M represents the current AVP value, C represents the current threshold, and the lower the value of J, the better the threshold is selected.

[0070] After PSO optimization, the accuracy of fault confirmation in the initial stage of engine misfire is improved, and the fault confirmation time is reduced from 1.36s to 0.96s, a speedup of 29.4%. This shows that PSO optimization of the misfire fault diagnosis rule threshold can effectively improve the fault identification accuracy and speed up the fault confirmation process.

[0071] Define fire detection capability (m) c ):

[0072]

[0073] Where m t It is the total number of fires, n d and n f These represent the number of missed detections and false positives, respectively. (m) c To clarify the fire detection capability of AVP; M is defined. A :

[0074]

[0075] In the formula, n is the number of cylinders in the engine. M A It is the average value of AVP for two engine cycles, used to eliminate AVP deviation and improve misfire detection accuracy.

[0076] The magnitude and accuracy of the AVP value directly determine the accuracy of engine misfire diagnosis.

[0077] AVP c =AVP-M A

[0078] Use compensated AVP c By eliminating misleading AVP bias, the fire detection results are smoothed out.

[0079] The instantaneous engine speed signal and motor speed signal in the signal processing module are acquired, and signal conversion and correction are performed to obtain the estimated torque. The fluctuation characteristics of the instantaneous engine crankshaft speed are one of the effective indicators reflecting engine torque. Fourier transform of the vehicle instantaneous speed signal and motor speed signal can obtain the fluctuation amplitude of the instantaneous engine crankshaft speed and the fluctuation amplitude of the motor torque. Algebraic difference is performed on the fluctuation amplitude of the instantaneous crankshaft speed to obtain the fluctuation amplitude of the engine at the signed firing frequency. The difference between the maximum and minimum instantaneous speed values ​​and the fluctuation amplitude of the instantaneous speed at the firing frequency are calibrated and compiled into a MAP (Motor Map). Torque estimation is then performed by looking up the MAP during engine operation.

[0080] Using the Map-Aspect Ratio (MAP) method, the correspondence between engine torque and motor torque and speed fluctuation amplitude under steady-state conditions and under dynamic conditions is obtained. Combining these steady-state and dynamic correspondences, torque estimation during actual vehicle operation is performed. Due to intake lag in turbocharged diesel engines during dynamic processes, the accuracy of torque estimation based on steady-state conditions is insufficient, leading to inaccurate motor torque compensation during real-vehicle testing. Therefore, torque correction is performed using signals such as throttle opening, intake pressure, and temperature. Finally, the corrected speed fluctuation amplitude is used for torque estimation.

[0081] A comparative analysis of the magnitudes of engine torque and motor torque with the corresponding speed fluctuation amplitudes revealed that the engine torque is on the order of 10 N·m, while the motor torque is on the order of 10 N·m. -4 The results showed that the torque fluctuation of the electric motor in the hybrid system was smaller than that of the engine and the whole vehicle, and therefore ignored it in the subsequent analysis.

[0082] The fault-tolerant control module drives the hybrid system to perform fault-tolerant control according to the VCU's instructions. After the VCU detects a misfire fault, the hybrid system compensates for the torque by distributing the motor based on the estimated torque. After compensation, the P2 hybrid system can continue to operate even with a single-cylinder misfire and remain within the economic range. Without fault-tolerant control, the engine output drops by 1 / 6 due to the single-cylinder misfire. Because of the insufficient output, the engine continuously increases fuel injection to drive other unaffected cylinders to share the reduced output, resulting in greater torque fluctuations in each cylinder and moving out of the economic range, increasing overall fuel consumption by 13%. With fault-tolerant control, the VCU calculates the torque fluctuations that the motor needs to compensate for based on the torque fluctuations of the engine and motor, driving the motor to compensate for the corresponding output. Meanwhile, each cylinder of the engine continues to operate within the economic range. This allows the vehicle to operate with a fault while maintaining overall fuel consumption at only 4%, demonstrating a significant effect.

[0083] The hybrid powertrain platform verification is based on fault-tolerant control of the hybrid power system. The host computer model loads and transmits data to the hybrid powertrain; the microcontroller writes the AVP calculation program; instantaneous speed signals are collected; the microcontroller program processes the instantaneous speed signals to obtain the AVP; the microcontroller program analyzes the AVP and determines whether misfire has occurred; the hybrid powertrain system transmits data signals for verification. The program flowchart is shown below. Figure 4 As shown. Verification demonstrates that this method achieves the intended effect on P2 hybrid vehicles, successfully performing fault diagnosis and fault-tolerant control.

[0084] The hybrid powertrain platform is the foundation for hybrid powertrain diagnostic testing. A real-time fault diagnosis simulation platform based on the hybrid powertrain and VCU was built. In misfire fault diagnosis, the main task of the host computer is to receive data from the hybrid powertrain and perform real-time fault diagnosis. The host computer of the hybrid powertrain platform mainly consists of a real-time clock module, a CAN receiver module, a data processing module, and a fault diagnosis module. The real-time clock module synchronizes the Simulink simulation time with the actual time, ensuring the model runs in a real-time environment. The CAN receiver module, built using the Vehicle Network toolbox, receives characteristic signals from the diesel-electric hybrid system, verifying the platform structure as shown. Figure 3 As shown.

[0085] The hardware layer uses a Freescale MC9S12 series microcontroller. The main working principle of the program is as follows: the time of the four rising edges is collected, the instantaneous speed of the engine is calculated, and after the starting point represented by the missing tooth is determined, the AVP is calculated. Different calculation methods are used for missing teeth and non-missing teeth. The AVP is obtained by using the formula, and the NL value obtained by the PSO algorithm is used to determine whether a misfire fault has occurred.

[0086] Based on hybrid power misfire diagnosis, relevant vehicle signals are collected to assess the engine's power and fuel economy. System-level regulation is then implemented via the electric motor to compensate for the loss of power and fuel economy caused by engine misfire. This fully leverages the advantages of the hybrid power system and enables fault-tolerant control at the system level, allowing the hybrid power system to maintain power and fuel economy even when engine misfire occurs.

[0087] This invention is capable of diagnosing misfire faults in hybrid power systems. It can effectively utilize the advantages of hybrid systems, drive motor torque compensation through control algorithms to achieve fault-tolerant control, and conduct experimental verification to prove the accuracy and reliability of misfire fault diagnosis.

[0088] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A device for diagnosing misfires in a hybrid power system, characterized in that: The device consists of four main parts: a host computer (PC), a hybrid powertrain, a vehicle communication unit (VCU), and a working module. The PC and VCU are connected via CAN. Data from the PC is transmitted to the hybrid powertrain via signal lines. The hybrid powertrain is connected to the VCU through sensors for real-time signal transmission and interaction. The working module comprises five modules: a signal acquisition module, a fault diagnosis module, a signal processing module, a fault-tolerant control module, and a verification module. These modules work in conjunction with the other three parts to achieve fire fault diagnosis. The device uses the PC to monitor and collect data and transmit it to the hybrid powertrain, monitoring its status in real time when a fire fault occurs. The signal acquisition module receives signals from the crankshaft signal disk of the hybrid powertrain engine, instantaneous engine speed signal, throttle opening, intake pressure, temperature and motor signal, including motor speed signal and motor voltage signal. The fault diagnosis module obtains the engine crankshaft signal disk signal, and works with the VCU to download the program via CAN based on the host PC. Combined with the real-time signal transmitted by the hybrid powertrain, it analyzes the hybrid power operating condition and diagnoses whether the engine has misfired. The signal processing module acquires the instantaneous engine speed signal and motor speed signal from the signal processing module under test, performs signal conversion and correction, and obtains the estimated torque, which is a preprocessing step for the subsequent acquisition of AVP value and motor torque compensation. The fault-tolerant control module receives the misfire judgment from the fault diagnosis module and the estimated torque from the signal processing module, transmits it to the hybrid powertrain system, and drives the hybrid powertrain to drive the engine and motor according to the VCU's instructions to perform fault-tolerant control of the hybrid powertrain system. The verification module loads the model and data onto a host PC and transmits it to the hybrid powertrain for real-time verification. AVP is the average power value, which is determined based on the duration of the expansion stroke of each cylinder. The time it takes for the engine crankshaft to rotate 180°. The time required for the next engine crankshaft to rotate 180°; When the engine is running normally, the AVP value is close to zero; A sudden change in the AVP value indicates that a fire has occurred.

2. The hybrid power system misfire fault diagnosis device as described in claim 1, characterized in that: The host computer PC consists of a model building section and a data acquisition and monitoring section. It can connect to the hybrid powertrain and collect data signals in real time through the loaded model and the installed monitoring platform software, thus playing the role of data collection and monitoring.

3. The hybrid power system misfire fault diagnosis device as described in claim 1, characterized in that: The signal transmission between the hybrid powertrain and the VCU is used for misfire diagnosis and fault-tolerant control of the hybrid powertrain.

4. A method for diagnosing misfires in a hybrid power system, implemented based on a misfire diagnosis device for a hybrid power system as described in claim 1, 2, or 3, characterized in that: Includes the following steps, Step 1: Obtain the instantaneous signal of the vehicle through the signal acquisition module; Step 2: Using the fault diagnosis module, combined with the VCU, real-time signals and the engine crankshaft signal disk signal obtained in Step 1, the engine misfire status is determined by the AVP value, and the misfire fault of the hybrid power system is accurately diagnosed. Step 3: Using the instantaneous vehicle signal obtained in Step 1, obtain the signed ignition frequency point speed fluctuation amplitude, and perform vehicle torque estimation to prepare for the fault-tolerant control in Step 4. Step 4: The fault-tolerant control module receives the AVP value from Step 2 to determine the misfire and the estimated torque from Step 3, and drives the hybrid power system according to the instructions of the VCU to perform fault-tolerant control of the hybrid power system. Step 5: Using the verification module, perform fault-tolerant control of the hybrid power system from Step 4.

5. The method for diagnosing misfires in a hybrid power system as described in claim 4, characterized in that: The implementation method of step one is as follows: 1.1 The signal acquisition module acquires the analog signal of the original instantaneous rotational speed of the vehicle component; 1.2 The obtained original analog signal is converted and calibrated to obtain the relationship between the original analog signal and the original digital signal. Filtering is then performed to obtain the instantaneous speed signal of the vehicle. 1.3 Through steps 1.1 and 1.2, obtain the engine crankshaft signal disk signal, throttle opening, intake pressure and temperature, motor speed signal and motor voltage signal.

6. The method for diagnosing misfire faults in a hybrid power system as described in claim 4, characterized in that: The implementation method of step four is as follows: The fault-tolerant control module addresses the issue of inaccurate misfire torque estimation due to sudden and uneven speed changes after a misfire. It performs misfire torque estimation, compares the estimated engine torque with the engine's required torque, and then corrects the motor torque to assist the engine torque, thereby bringing the vehicle to a balanced state. The hybrid system receives the demand for motor torque and drives it according to the VCU's instructions, performing fault-tolerant control of the hybrid system based on the engine misfire fault.

7. The method for diagnosing misfire faults in a hybrid power system as described in claim 4, characterized in that: Step five is implemented as follows: The microcontroller is programmed with an AVP calculation program; the instantaneous engine speed signal is acquired; the microcontroller program processes the instantaneous speed signal to obtain the AVP; the microcontroller program analyzes the AVP and determines whether there is a misfire; and the data signal transmitted by the hybrid powertrain system is verified.

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