CN108248598B - System and method for failure control of in-wheel motor driven hybrid electric vehicle - Google Patents

Abstract

The invention provides a failure control method for a hub motor-driven hybrid electric vehicle. Firstly, parallel failure failure trend identification: according to the characteristic parameters corresponding to different failure failures, a variety of message signals are selected for trend identification or judgment of failure failures; specifically Including electronic pedals, power battery-high voltage management system, engine-generator direct connection system and distributed in-wheel motor drive system fault identification; then according to the failure fault trend identification results, the failure is eliminated by actively adjusting the control strategy of the distributed in-wheel motor drive system Fault pre-processing; finally, according to the severity, the failure faults that have occurred are classified into two levels of warning and alarm, and are dealt with according to the level. The fault judgment and processing among the various systems is a parallel structure, and they work together to actively adjust the control strategy of the distributed in-wheel motor drive system under the premise of ensuring the safety of the vehicle to ensure that the vehicle is in the face of failures. driving stability.

Description

System and method for failure control of in-wheel motor driven hybrid electric vehicle

technical field

The invention belongs to the technical field of hub motor distributed drive vehicle control, and in particular relates to a failure control system and method for a hub motor driven hybrid vehicle.

Background technique

As shown in Figure 1, the failure control system of an in-wheel motor-driven hybrid electric vehicle is mainly composed of an engine-generator direct connection system, a power battery-high voltage management system, an in-wheel motor-in-wheel motor controller drive system, an electronic pedal system, and a vehicle controller. Composition, each system performs energy transfer through high-voltage cables, and performs information exchange through low-voltage CAN lines. Compared with traditional vehicles, the complexity of the system is high, and the state information of each system is complex. Therefore, how to actively judge the trend of failures, reasonably carry out redundant control of the whole vehicle, and design a better control system architecture is the key to the failure of the whole vehicle. One of the key technologies of the control system.

Compared with centralized drive electric vehicles, distributed in-wheel motor drive vehicles can precisely control each wheel individually. On the one hand, it can improve the control effect of the vehicle in terms of power, passability, drive anti-skid, vehicle stability, and vehicle efficiency optimization; Stability has an impact. Therefore, how to coordinate the failure processing modules of each system with the in-wheel motor drive system to ensure vehicle driving stability and safety is one of the difficulties in the vehicle failure control system.

At the same time, the failures of multiple in-wheel motor drive systems have multiple combination states, and different combination states require different processing methods to ensure driving safety under various driving conditions. Therefore, the design of the in-wheel motor drive system failure fault handling module based on vehicle dynamics is one of the difficulties in the vehicle failure fault control system.

Contents of the invention

The technical problem to be solved by the present invention is to provide a failure control system and method for an in-wheel motor-driven hybrid electric vehicle, so as to ensure the driving stability of the vehicle in the face of a failure.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for controlling the failure of an in-wheel motor-driven hybrid electric vehicle, which is characterized in that it includes the following steps:

S1. Failure trend identification: According to the characteristic parameters corresponding to different failures, select a variety of message signals to identify or determine the trend of failures; specifically include:

Electronic pedal failure fault identification: According to the opening signal of the electronic pedal, logically judge and identify the failure faults that have occurred in the electronic pedal system;

Power battery-high voltage management system fault identification: According to the message information that the high voltage management system feeds back to the vehicle controller that can represent the failure of the power battery and the vehicle's high voltage safety system, the types of failures that occur in the power battery and the vehicle's high voltage safety system Identify failure trends and possibilities, and identify the types of power battery and vehicle high-voltage safety system failures that have occurred;

Fault identification of the engine-generator direct connection system: According to the message information that the generator and the engine feed back to the vehicle controller that can represent the failure of the generator and the engine, combined with the generator bus voltage, bus current, generator speed, power generation The generator stator temperature and the temperature of the generator controller are used to identify the failure trend of the generator and engine failure and the possibility of failure, and to identify the types of generator and engine failures that have occurred;

Distributed in-wheel motor drive system: According to the message information that can represent the failure of each in-wheel motor drive system fed back to the vehicle controller by the in-wheel motor drive system, combined with the bus voltage, bus current, in-wheel motor speed, in-wheel motor Stator temperature and in-wheel motor controller temperature, identify the failure trend of each in-wheel motor drive system failure type and possibility, and identify the types of in-wheel motor drive system failures that have occurred;

S2. Failure pretreatment: According to the identification result of the failure trend, the failure pretreatment is carried out by actively adjusting the control strategy of the distributed in-wheel motor drive system; specifically includes:

Power battery-high voltage management system failure fault pretreatment: by limiting the required power of the vehicle and controlling the sound and light alarm device to prompt the driver to ensure the safe deceleration of the vehicle;

Engine-generator direct connection system failure fault pre-treatment: by limiting the required power of the vehicle and controlling the sound and light alarm device to remind the driver to ensure the safe deceleration of the vehicle;

Distributed in-wheel motor drive system failure fault pre-processing: calculate vehicle speed, body attitude signal, limit the required power of the target in-wheel motor and coaxial opposite in-wheel motor, control the sound and light alarm device to prompt the driver, and ensure the safe deceleration of the vehicle;

S3. Post-processing of grading failures that have occurred: According to the severity, the failures that have occurred are classified into two levels of warning and alarm, and are processed separately according to the level; specifically include:

Electronic pedal system processing: When only one electronic pedal opening signal is faulty, it is a warning, and a normal opening signal is used to convey the driver's intention, and the torque command sent to each hub motor drive system is halved ; If the two opening signals are faulty, it will be an alarm, and then limit the output power of all hub motor drive systems and enter the limp mode;

Power battery-high voltage management system processing: warning, the power battery will limit the charging and discharging power by itself, limit the output power of all hub motor drive systems, and enter the limp mode; alarm, cut off the high voltage of the whole vehicle, and the vehicle will be decelerated by the driver operating the brake pedal until parking;

Engine-generator direct connection system processing: warning, the engine-generator system limits the output power by itself, and at the same time limits the torque command sent to each hub motor drive system; alarm, the engine-generator direct connection system enters the unloading protection mode to work , the generator is idling, limiting the output power of all hub motor drive systems, and entering limp mode;

Distributed hub motor drive system processing: warning, then the hub motor drive system limits the output power by itself, and the vehicle controller synchronously limits the torque command of the target hub motor drive system and the coaxial opposite side hub motor drive system to avoid the additional yaw moment When an alarm is generated, the in-wheel motor drive system unloads and idles, limiting the required power of the vehicle, the vehicle enters the brake priority mode, and the driver parks safely through the power steering and brake power systems.

According to the above method, this method also includes high-voltage power-on self-inspection: during the high-voltage power-on link, it is checked whether there are failures in each system of the vehicle. If there is a failure or a CAN line communication problem, the vehicle controller determines that the high-voltage power-on Success, unable to drive.

According to the above method, the opening signal of the electronic pedal is collected by the rotation angle sensor, filtered by the average value filter technology after AD conversion, and 2 channels of one high and one low digital signals with a 2-fold proportional relationship within the stroke are output.

According to the above method, using the one high and one low digital signal, using the rate-of-change limit diagnosis module, the failure fault of the electronic pedal system is divided into two types: sudden change and stagnation;

The rate-of-change limit diagnostic module specifically judges in the following manner: if the two sampling values of Pedal_H or Pedal_L remain unchanged and occur more than N times in 2N sampling times or occur continuously N times, then it is considered that there has been electronic pedal stagnation Fault; if the difference between the two sampling values of Pedal_H or Pedal_L exceeds the threshold and the number of occurrences in 2N samples exceeds N times or occurs continuously N times, it is considered that there is a sudden failure of the electronic pedal; N is the preset number of sampling times.

According to the above method, when judging the failure of the electronic pedal system, the sporadic faults and short-term disturbances of the high and low digital signals are filtered, and the sporadic faults and short-term disturbances are faults or digital signals. Interference time is less than the predetermined number of seconds.

According to the above method, the opening degree of the electronic pedal system is calculated based on the high digital signal, and the low digital signal is used to compare with the high digital signal to judge the rationality of the digital signal.

According to the above method, the calculated opening of the electronic pedal system is compared with the pre-stored opening threshold, and the failure faults of the signal line short circuit to ground, short circuit to power supply and open circuit are judged.

According to the above method, in the S3, sound and light alarms are also performed according to levels.

A failure control system for a hub motor driven hybrid electric vehicle, characterized in that it includes a generator controller, a generator, a power battery-high voltage management system, a vehicle controller, an electronic pedal system, a hub motor, a hub motor controller and a memory ;in,

The drive signal input terminal and the state feedback signal output terminal of the generator are respectively connected with the drive signal output terminal and the generator state feedback signal input terminal of the generator controller, and the control signal input terminal and the state feedback signal output terminal of the generator controller are respectively Connect with the control signal output terminal and the state feedback signal input terminal of the vehicle controller;

The control signal input terminal and the status feedback signal output terminal of the power battery-high voltage management system are respectively connected with the control signal output terminal and the status feedback signal input terminal of the vehicle controller;

The electronic pedal system includes an electronic brake pedal and an electronic accelerator pedal. The electronic brake pedal and the electronic accelerator pedal respectively output an analog opening signal through a rotation angle sensor, which is converted into a digital signal by an AD conversion device. The digital signal output terminal is connected with the vehicle controller. State feedback signal input connection;

The drive signal input end and the state feedback signal output end of the hub motor are respectively connected to the drive signal output end of the hub motor controller and the input end of the hub motor state feedback signal, and the control signal input end and the state feedback signal output end of the hub motor controller are respectively Connect with the control signal output terminal and the state feedback signal input terminal of the vehicle controller;

When the four in-wheel motors are in the driving state, the power battery pack and the generator coordinate and cooperate. When the driving load is low, the power battery receives the excess electric energy of the generator. When the driving load is high, the power battery and the generator provide power to the in-wheel motor. electric energy;

The generator and the engine system are mechanically connected, and the engine drives the generator to generate electricity;

A controller program is stored in the memory for calling by the vehicle controller, so as to complete the failure control method for the in-wheel motor-driven hybrid electric vehicle.

The beneficial effects of the present invention are: the failure judgment and processing among the electronic pedal, the power battery-high voltage management system, the engine-generator direct connection system, and the distributed in-wheel motor drive system are in a parallel structure, each of which is about to occur and has occurred Judging the failure of the vehicle and working together with each other, the control strategy of the distributed in-wheel motor drive system can be actively adjusted under the premise of ensuring the driving safety of the vehicle to ensure the driving stability of the vehicle in the face of a failure. The failures that have occurred are handled in a graded manner.

Description of drawings

Figure 1 is a parallel structure diagram of the failure processing module of the whole vehicle.

Fig. 2 is a framework diagram of a fault handling method for graded failures of the electronic pedal system.

Fig. 3 is a framework diagram of a fault handling method for graded failures of the power battery-high voltage management system.

Fig. 4 is a framework diagram of a fault handling method for graded failures of the engine-generator direct connection system.

Fig. 5 is a framework diagram of a fault handling method for graded failures of a distributed in-wheel motor drive system.

Detailed ways

The present invention will be further described below in conjunction with specific examples and accompanying drawings.

The present invention provides an in-wheel motor-driven hybrid vehicle failure control system, as shown in Figure 1, including a generator controller, a generator, a power battery-high voltage management system, a vehicle controller, an electronic pedal system, an in-wheel motor, and a wheel hub The motor controller and the memory communicate with each other through CAN lines or transmit electric energy through high-voltage cables. Among them, the vehicle controller plays the role of judging and identifying and mobilizing other systems to work together. in,

The drive signal input terminal and the state feedback signal output terminal of the generator are respectively connected with the drive signal output terminal and the generator state feedback signal input terminal of the generator controller, and the control signal input terminal and the state feedback signal output terminal of the generator controller are respectively Connect with the control signal output terminal and the state feedback signal input terminal of the vehicle controller;

The control signal input terminal and the status feedback signal output terminal of the power battery-high voltage management system are respectively connected with the control signal output terminal and the status feedback signal input terminal of the vehicle controller;

The electronic pedal system includes an electronic brake pedal and an electronic accelerator pedal. The electronic brake pedal and the electronic accelerator pedal respectively output an analog opening signal through a rotation angle sensor, which is converted into a digital signal by an AD conversion device. The digital signal output terminal is connected with the vehicle controller. State feedback signal input connection;

The drive signal input end and the state feedback signal output end of the hub motor are respectively connected to the drive signal output end of the hub motor controller and the input end of the hub motor state feedback signal, and the control signal input end and the state feedback signal output end of the hub motor controller are respectively Connect with the control signal output terminal and the state feedback signal input terminal of the vehicle controller;

When the four in-wheel motors are in the driving state, the power battery pack and the generator coordinate and cooperate. When the driving load is low, the power battery receives the excess electric energy of the generator. When the driving load is high, the power battery and the generator provide power to the in-wheel motor. electric energy;

The generator and the engine system are mechanically connected, and the engine drives the generator to generate electricity;

A controller program is stored in the memory for calling by the vehicle controller, so as to complete the failure control method for the hybrid electric vehicle driven by the in-wheel motor.

The described in-wheel motor drive hybrid electric vehicle failure control method, it comprises the following steps:

S1. Failure trend identification: According to the characteristic parameters corresponding to different failures, select a variety of message signals to identify or determine the trend of failures; specifically include:

Electronic pedal failure fault identification: According to the opening signal of the electronic pedal, logically judge and identify the failure faults that have occurred in the electronic pedal system.

When the electronic pedal is working, the rotation angle sensor assembled on the pedal will output an analog signal, and after the analog signal is collected, there will inevitably be pulse interference. The digital signal output by the electronic pedal is filtered by using the mean value filter technology, which effectively improves the smoothness of the digital signal; at the same time Set the two output digital signals of the electronic pedal as high and low: Pedal_Input_H and Pedal_Input_L, the two signals have a 2-fold proportional relationship within the stroke: Pedal_Input_H≈Pedal_Input_L*2, the dual-channel setting is fault-tolerant compared with the single-channel setting The rate is higher and the fault identification effect is better. The failure faults include digital signal mutation faults, digital signal stagnation faults, digital signal rationality faults, electronic pedal circuit short-circuit faults to ground, electronic pedal circuit short-circuit faults to power supply and electronic pedal circuit open circuit faults.

The digital signal of the electronic pedal is filtered and analyzed with a specific resolution, so that the digital signal output by the acceleration and brake pedals can represent the real-time opening of the pedal in the form of a percentage, which can better reflect the driver's intention, and then control the entire vehicle. The controller calculates the real-time peak output power of the power system according to the driving mode (hybrid drive/pure electric drive) and multiplies it with the real-time pedal opening (percentage) output by the electronic accelerator pedal to obtain the real-time output power sent by the vehicle controller to the in-wheel motor drive system At the same time, there are a variety of redundant controls that affect the power request in real time, such as drive anti-skid control, drive force adaptive control, generator loading control, power battery charge and discharge power adaptive control, etc. However, when the corner sensor of the electronic pedal fails, the digital signal will be distorted, the vehicle cannot respond to the driver's intention, and even seriously affect the driving safety of the vehicle; in view of the above situation, according to the obtained electronic The two output signals of pedals, Pedal_Input_H and Pedal_Input_L, use the rate of change limit value diagnosis to divide the failure of digital signals into two types: sudden change and stagnation. If the value of the two samples of Pedal_H or Pedal_L remains unchanged and the number of occurrences exceeds the predetermined number of samples (for example, 100 times) in 200 samples, or the predetermined number of samples occurs continuously (for example, 100 times), it is considered that there is an electronic pedal stagnation fault; If the difference between the two sampling values of Pedal_H or Pedal_L exceeds the threshold and the number of occurrences in the predetermined number of samplings (for example, 200) exceeds half or half of the number of consecutive occurrences, it is considered that there is an electronic pedal mutation fault.

There are sporadic faults and short-term interference in the dual-channel signal, which will trigger the failure classification processing module of the electronic pedal system for a short time and suddenly, which will affect the continuity of the electronic pedal system's recognition of the driver's intentions, resulting in severe damage to the ride comfort. In view of the above situation, the fault debounce technology is used to effectively filter the occasional fault or short-term interference of the dual-channel signal, avoiding the short-term trigger of the fail-safe program.

Calculate the pedal opening according to the high signal Pedal_Input_H in the two output signals of the electronic pedal, and use the dual-channel comparison method to monitor the high in real time according to the low signal Pedal_Input_L in the two output signals of the electronic pedal obtained in step 2-1. Whether there is a reasonable fault in the digital signal of the channel.

According to the obtained two-way output signal of the electronic pedal, threshold value diagnosis/limit value diagnosis method is used to compare the filtered acceleration/brake pedal signal with the threshold value pre-stored in the vehicle controller, which can effectively diagnose the short circuit of the signal line to ground , Faults such as short circuit and open circuit of the power supply.

Power battery-high voltage management system fault identification: According to the message information that can represent the failure of the power battery and the vehicle high voltage safety system fed back to the vehicle controller by the high voltage management system (BMS), the failure of the power battery and the vehicle high voltage safety system The types and possibilities of failures are identified for failure failure trends, and the types of failures of power batteries and vehicle high-voltage safety systems that have occurred are identified.

Fault identification of the engine-generator direct connection system: According to the message information that the generator and the engine feed back to the vehicle controller that can represent the failure of the generator and the engine, combined with the generator bus voltage, bus current, generator speed, power generation The generator stator temperature and the temperature of the generator controller are used to identify the failure trend of the generator and engine failure and the possibility of failure, and to identify the types of generator and engine failures that have occurred.

Distributed in-wheel motor drive system: According to the message information that can represent the failure of each in-wheel motor drive system fed back to the vehicle controller by the in-wheel motor drive system, combined with the bus voltage, bus current, in-wheel motor speed, in-wheel motor The temperature of the stator and the temperature of the hub motor controller are used to identify the failure trend of each hub motor drive system and the possibility of failure, and to identify the types of failures of each hub motor drive system that have occurred.

S2. Failure pretreatment: According to the identification result of the failure trend, the failure pretreatment is carried out by actively adjusting the control strategy of the distributed in-wheel motor drive system; specifically includes:

Power battery-high voltage management system failure fault pre-processing: After identifying the power battery failure tendency or the vehicle high-voltage system has potential safety hazards, the vehicle controller will halve the resolution of the accelerator pedal and control the sound and light alarm device, so that The driver and the power battery-high voltage management system failure failure processing module work together to control the failure failure as far as possible in the non-triggered state on the premise of ensuring the safe deceleration of the vehicle.

Engine-generator direct connection system failure fault pre-processing: After identifying the generator and engine failure tendency, the vehicle controller will halve the resolution of the accelerator pedal and control the sound and light alarm device, so that the driver and the engine-generator The failure fault processing module of the machine direct connection system works together to control the failure fault in the untriggered state as much as possible on the premise of ensuring the safe deceleration of the vehicle.

Distributed in-wheel motor drive system failure fault pre-processing: After identifying one or more in-wheel motor-in-wheel motor controller systems with a tendency to fail, comprehensively calculate the vehicle speed and body attitude signals to obtain the torque command adjustment value △T. Under the premise of ensuring driving stability, the vehicle controller synchronously reduces the torque command sent to the target hub motor and the coaxial opposite hub motor according to △T, controls the sound and light alarm device, and makes the driver and the distributed hub motor drive system invalid The fault processing modules work together to control the failure fault as far as possible in the non-triggered state on the premise of ensuring the safe deceleration of the vehicle.

S3. Classified post-processing of failed failures that have occurred: According to the severity, the failed failures that have occurred are classified into two levels of warning "warning" and alarm "alarm", and are processed according to the level. When the vehicle tends to fail, the vehicle controller will actively adjust the required power of the vehicle and cooperate with the driver's deceleration operation to safely decelerate the vehicle. Failure fault, each parallel working module starts to carry out the classification post-processing of failure fault. Specifically include:

Electronic pedal system processing: When only one electronic pedal opening signal is faulty, it is a warning, and a normal opening signal is used to convey the driver's intention, and the torque command sent to each hub motor drive system is halved ; If the two opening signals are faulty, it will be an alarm, and then limit the output power of all hub motor drive systems and enter the limp mode. Specifically, deal with the "warning" early warning failure of the electronic pedal system: the vehicle controller uses a normal pedal signal to convey the driver's intention, and halves the torque command sent to each hub motor drive system, so that the vehicle runs at a relative In a safe low power state, the vehicle controller triggers a "warning" alarm signal. Handle the early warning failure of the electronic pedal system "alarm": The vehicle controller severely restricts the output power of all hub motor drive systems based on the calculated slow-speed driving resistance power, and limits the maximum speed of the vehicle to within 5km/h, that is, enters the limp mode. The vehicle controller triggers an "alarm" alarm signal.

Power battery-high voltage management system processing: warning, the power battery will limit the charging and discharging power by itself, limit the output power of all hub motor drive systems, and enter the limp mode; alarm, cut off the high voltage of the whole vehicle, and the vehicle will be decelerated by the driver operating the brake pedal until parking. Specifically, deal with the "warning" early warning failure of the power battery-high voltage management system: the power battery limits the charging and discharging power by itself. Considering that if the failure level continues to upgrade, the high voltage of the vehicle will be cut off, the brakes and steering power will be lost, and the driver will not be able to control it safely. The vehicle stops, so the vehicle controller severely restricts the output power of all in-wheel motor drive systems according to the calculated slow-speed driving resistance power, and limits the vehicle's maximum speed within 5km/h, that is, it enters the limp mode and triggers the "warning" signal at the same time . Deal with the "alarm" early warning failure of the power battery-high voltage management system: the power battery-high voltage system cuts off the high voltage of the vehicle, the driver operates the brake pedal to decelerate the vehicle until it stops, and the "alarm" signal is triggered at the same time.

Engine-generator direct connection system processing: warning, the engine-generator system limits the output power by itself, and at the same time limits the torque command sent to each hub motor drive system; alarm, the engine-generator direct connection system enters the unloading protection mode to work , the generator idles, limiting the output power of all hub motor drive systems, and entering limp mode. Specifically, deal with the "warning" early warning failure of the engine-generator direct connection system: the engine-generator system limits the output power by itself, and at the same time, the vehicle controller limits the output power of all in-wheel motor drive systems according to the calculated medium-speed driving resistance power , to limit the maximum speed of the vehicle within 30km/h, that is, to limit the torque command sent to each hub motor drive system and trigger the "warning" early warning signal. Deal with the "alarm" alarm failure of the engine-generator direct connection system: the engine-generator direct connection system enters the unloading protection mode to work, and the generator is idling to prevent irreversible damage to the generator system. The high-speed driving resistance power severely limits the output power of all in-wheel motor drive systems, and limits the vehicle's maximum speed within 5km/h, that is, the pure electric limp mode, and triggers the "alarm" signal at the same time.

Distributed hub motor drive system processing: warning, then the hub motor drive system limits the output power by itself, and the vehicle controller synchronously limits the torque command of the target hub motor drive system and the coaxial opposite side hub motor drive system to avoid the additional yaw moment When an alarm is generated, the in-wheel motor drive system unloads and idles, limiting the required power of the vehicle, the vehicle enters the brake priority mode, and the driver parks safely through the power steering and brake power systems. Specifically, deal with the "warning" early warning fault of the distributed hub motor drive system: the hub motor drive system limits the output power by itself, and the vehicle controller synchronously limits the torque commands of the target hub motor drive system and the coaxial opposite side hub motor drive system to avoid The generation of additional yaw moment triggers the "warning" signal at the same time. Handle the "alarm" alarm fault of the distributed hub motor drive system: the hub motor drive system is unloaded and idling. In order to prevent irreversible damage to the hub motor system and ensure the driving stability of the vehicle, the required power of the vehicle is reduced to zero, and the vehicle enters the brake In priority mode, the driver parks safely through the power steering and brake power systems, and at the same time triggers the "alarm" signal.

The method also includes high-voltage power-on self-inspection: during the high-voltage power-on link, it is checked whether each system of the vehicle has a failure fault. If there is a failure fault or a CAN line communication problem, the vehicle controller judges that the high-voltage power-on is unsuccessful and cannot drive. .

The failure processing module of the whole vehicle of the present invention is not only applicable to the distributed drive vehicle of the serial hybrid in-wheel motor shown in Fig. Identify and process to ensure that highly electrified distributed drive vehicles safely respond to failures of high-voltage drive components, high-voltage energy storage components, and electrified accessories during power-on and driving.

The above embodiments are only used to illustrate the design concept and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims (9)

1. A failure control method for a hub motor driven hybrid electric vehicle is characterized by comprising the following steps: it comprises the following steps:

s1, identifying failure fault trend: selecting various message signals to perform trend identification or judgment on the failure faults according to the characteristic parameters corresponding to different failure faults; the method specifically comprises the following steps:

electronic pedal failure fault identification: according to the opening degree signal of the electronic pedal, carrying out logic judgment and identification on the failure fault of the electronic pedal system;

power battery-high voltage management system fault identification: according to message information which is fed back to a vehicle controller by a high-voltage management system and can represent failure faults of a power battery and a vehicle high-voltage safety system, failure fault trend identification is carried out on the types and the possibility of failure faults of the power battery and the vehicle high-voltage safety system, and the types of failure faults of the power battery and the vehicle high-voltage safety system which occur are identified;

engine-generator direct connection system fault identification: according to message information which is fed back to a vehicle control unit by a generator and an engine and can represent failure faults of the generator and the engine, and by combining bus voltage, bus current, generator rotating speed, generator stator temperature and generator controller temperature of the generator, failure fault trend identification is carried out on the type and possibility of failure faults of the generator and the engine, and the type of failure faults of the generator and the engine which occur is identified;

distributed in-wheel motor drive system: according to message information which is fed back to the whole vehicle controller by the hub motor driving systems and can represent failure faults of all the hub motor driving systems, and by combining bus voltage, bus current, hub motor rotating speed, hub motor stator temperature and hub motor controller temperature of all the hub motors, failure fault trend identification is carried out on the types and the possibility of failure faults of all the hub motor driving systems, and the types of the failure faults of all the hub motor driving systems which occur are identified;

s2, failure fault preprocessing: according to the failure fault trend recognition result, performing failure fault preprocessing by actively adjusting a control strategy of the distributed hub motor driving system; the method specifically comprises the following steps:

power battery-high voltage management system failure fault preprocessing: the driver is prompted by limiting the required power of the whole vehicle and controlling the audible and visual alarm device, so that the safe deceleration of the vehicle is ensured;

preprocessing the failure fault of the engine-generator direct connection system: the driver is prompted by limiting the required power of the whole vehicle and controlling the audible and visual alarm device, so that the safe deceleration of the vehicle is ensured;

preprocessing failure faults of a distributed hub motor driving system: calculating a vehicle speed and a vehicle body posture signal, limiting the required power of a target hub motor and a coaxial opposite side hub motor, and controlling an audible and visual alarm device to prompt a driver so as to ensure the safe deceleration of the vehicle;

s3, classification post-processing of the generated failure fault: carrying out two-stage classification of warning and alarming on the failure fault according to the severity, and respectively processing according to the levels; the method specifically comprises the following steps:

and (3) processing by the electronic pedal system: when only one path of opening signal of the electronic pedal is in fault, the electronic pedal is warned, one path of normal opening signal is adopted to convey the intention of a driver, and the torque command sent to each hub motor driving system is halved; if the two paths of opening signals have faults, alarming is carried out, the output power of all the hub motor driving systems is limited, and a limping mode is entered;

power battery-high voltage management system processing: warning, the power battery automatically limits the charge and discharge power, limits the output power of all hub motor driving systems, and enters a limp mode; alarming, cutting off the high pressure of the whole vehicle, and decelerating the vehicle until the vehicle stops by the driver operating a brake pedal;

processing by an engine-generator direct connection system: warning, the engine-generator system self-limits output power while limiting torque commands sent to each in-wheel motor drive system; alarming, wherein the engine-generator direct connection system enters an unloading protection mode to work, the generator idles, the output power of all hub motor driving systems is limited, and a limp mode is entered;

processing by a distributed hub motor driving system: when the vehicle is warned, the hub motor driving system automatically limits the output power, and the vehicle control unit synchronously limits the torque commands of the target hub motor driving system and the coaxial opposite-side hub motor driving system so as to avoid the generation of additional yaw moment; and alarming, wherein the hub motor driving system unloads and idles to limit the power required by the whole vehicle, the vehicle enters a brake priority mode, and a driver safely stops through the steering power-assisted system and the brake power-assisted system.

2. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 1, characterized in that: the method also comprises the following steps of high-voltage power-on self-detection: and in the high-voltage electrifying link, whether each system of the vehicle has failure faults or not is checked, and if the failure faults or the CAN line communication problem exists, the whole vehicle controller judges that the high-voltage electrifying is unsuccessful and the vehicle cannot be driven.

3. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 1, characterized in that: the opening degree signal of the electronic pedal is collected through a corner sensor, is filtered through an average value filtering technology after being subjected to AD conversion, and outputs 2 paths of high-one-low digital signals with a 2-time proportional relation in the stroke, wherein the high digital signals are 2 times of the low digital signals.

4. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 3, characterized in that: dividing the failure fault of the electronic Pedal system into a sudden change fault and a stagnation fault by using the high-low digital signals, namely the PEdal _ H and the PEdal _ L, and a change rate limit value diagnosis module;

the change rate limit value diagnosis module specifically judges according to the following modes: if the values of the two times of sampling of the Pelal _ H or the Pelal _ L are unchanged and the occurrence frequency exceeds N times in the 2N times of sampling or continuously occurs N times, the stagnation fault of the electronic Pedal is considered to occur; if the difference of the values of two times of sampling of the Pelal _ H or the Pelal _ L exceeds a threshold value and the occurrence frequency in 2N times of sampling exceeds N times or continuously occurs N times, the electronic Pedal sudden change fault is considered to occur; and N is the preset sampling times.

5. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 4, characterized in that: when the failure fault of the electronic pedal system is judged, the accidental fault and the short-time interference existing in a high-low digital signal are filtered, wherein the accidental fault and the short-time interference are faults or the time of the digital signal interference is less than a preset number of seconds.

6. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 3, characterized in that: and calculating the opening degree of the electronic pedal system by taking the high digital signal as a reference, and comparing the low digital signal with the high digital signal to judge the rationality fault of the digital signal.

7. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 6, characterized in that: and comparing the calculated opening degree of the electronic pedal system with a prestored opening degree threshold value, and judging the failure faults of the signal line, such as short circuit to the ground, short circuit to the power supply and open circuit.

8. The in-wheel motor driven hybrid electric vehicle failure control method according to claim 1, characterized in that: in S3, sound and light alarm is performed according to the grade.

9. The utility model provides an in-wheel motor drive hybrid vehicle failure control system which characterized in that: the system comprises a generator controller, a generator, a power battery-high voltage management system, a vehicle control unit, an electronic pedal system, a hub motor controller and a memory; wherein,

the driving signal input end and the state feedback signal output end of the generator are respectively connected with the driving signal output end and the state feedback signal input end of the generator controller, and the control signal input end and the state feedback signal output end of the generator controller are respectively connected with the control signal output end and the state feedback signal input end of the whole vehicle controller;

the control signal input end and the state feedback signal output end of the power battery-high voltage management system are respectively connected with the control signal output end and the state feedback signal input end of the whole vehicle controller;

the electronic pedal system comprises an electronic brake pedal and an electronic accelerator pedal, the electronic brake pedal and the electronic accelerator pedal respectively output an analog opening degree signal through a rotation angle sensor, the analog opening degree signal is converted into a digital signal through an AD (analog-to-digital) conversion device, and the digital signal output end is connected with the state feedback signal input end of the whole vehicle controller;

the driving signal input end and the state feedback signal output end of the hub motor are respectively connected with the driving signal output end and the state feedback signal input end of the hub motor controller, and the control signal input end and the state feedback signal output end of the hub motor controller are respectively connected with the control signal output end and the state feedback signal input end of the whole vehicle controller;

when the four hub motors are in a driving state, the power battery pack is in coordination with the generator, when the driving load is low, the power battery receives redundant electric energy of the generator, and when the driving load is high, the power battery and the generator provide electric energy for the hub motors together;

the generator is mechanically connected with the engine system, and the engine drives the generator to generate electricity;

the memory stores a controller program for the vehicle control unit to call, so as to complete the method for controlling the failure of the in-wheel motor driven hybrid electric vehicle according to any one of claims 1 to 8.