Electro-hydraulic power-assisted steering system of new energy automobile and control method of electro-hydraulic power-assisted steering system

Abstract

The invention belongs to the technical field of new energy automobile steering systems, and discloses a new energy automobile electric hydraulic power-assisted steering system and a control method thereof.The system integrates a double-source redundant hydraulic power unit, a hydraulic adjusting unit, a multi-dimensional working condition sensing unit and an intelligent main controller; the multi-dimensional working condition sensing unit is integrated with a road adhesion coefficient detection module and a battery remaining capacity detection module. The control method is layered look-ahead matching control and is executed by an intelligent main controller in parallel: a power-assisted decision-making layer divides a three-stage power-assisted mode according to multi-dimensional perception information, and limits a steering angular velocity when power-assisted is enhanced on a low-attached road surface; the energy optimization layer predicts and implements prospective energy storage and pump rotating speed self-adaptive adjustment based on the intention of a driver; and the fault diagnosis layer realizes rapid fault identification and redundancy switching through multi-parameter collaborative diagnosis. The contradiction of high energy consumption, response delay and weak safety guarantee of a traditional system is solved, and power-assisted steering which is safe, energy-saving, fast in response and high in adaptability is achieved.

Description

An electric hydraulic power steering system for new energy vehicles and its control method Technical Field

[0001] This invention relates to the field of steering system technology for new energy vehicles, and in particular to an electro-hydraulic power steering system for new energy vehicles and its control method. Background Technology

[0002] The most common type of power steering device in the market for new energy electric vehicles is the electric hydraulic power steering (EHPS). The vehicle power supply unit provides a stable power supply to the electric hydraulic power steering (EHPS) product through an inverter, driving the EHPS product to operate at its rated speed and providing steering assistance to the vehicle.

[0003] However, these mainstream EHPS systems suffer from a fundamental technical contradiction: to meet the rapid dynamic response required for power steering, their electric pumps typically need to maintain high standby speeds or frequently start and stop at high speeds. This results in significant standby and operating power consumption, directly conflicting with the core requirement of new energy vehicles to pursue extreme energy efficiency to extend driving range. If a speed reduction or intermittent operation strategy is adopted for energy saving, it will inevitably introduce power steering delay, affecting steering feel and driving safety. Summary of the Invention

[0004] The present invention aims to provide an electric hydraulic power steering system for new energy vehicles and its control method thereon, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an electric hydraulic power steering system for new energy vehicles, comprising a steering gear, hydraulic oil pipes, a reservoir, a multi-dimensional working condition sensing unit, a dual-source redundant hydraulic power unit, an intelligent main controller, and a hydraulic adjustment unit; the multi-dimensional working condition sensing unit includes a steering wheel torque sensor, a vehicle speed sensor, a lateral acceleration sensor, a battery remaining power detection module, and a road surface adhesion coefficient detection module; the road surface adhesion coefficient detection module communicates with the vehicle's electronic stability program system via a controller area network bus to obtain an estimated value of the road surface adhesion coefficient; all sensors and detection modules communicate bidirectionally with the intelligent main controller via the controller area network bus to collect real-time data on vehicle driving and steering requirements; the dual-source redundant hydraulic power unit includes a main electro-hydraulic pump, an auxiliary electro-hydraulic pump, a dual-winding switching controller, and a hydraulic accumulator. The main electro-hydraulic pump and the auxiliary electro-hydraulic pump are connected in parallel to the hydraulic circuit. The hydraulic accumulator is connected in series with the outlet of the main electro-hydraulic pump to store high-pressure oil and quickly replenish it. The main electro-hydraulic pump is driven by a high-pressure, high-flow permanent magnet synchronous motor, and the auxiliary electro-hydraulic pump is driven by a low-pressure, low-flow brushless DC motor. The intelligent main controller is configured to execute control logic for fault diagnosis, power-assisted decision-making, and energy optimization, and is equipped with a dual-controller local area network bus channel redundant communication interface. The intelligent main controller communicates with the multi-dimensional operating condition sensing unit, the dual-source redundant hydraulic power unit, the vehicle controller, and the battery management system, and is configured to receive multi-dimensional operating condition data, issue control commands, and execute corresponding control methods. The hydraulic adjustment unit includes a proportional solenoid valve, a pressure sensor, and a flow sensor, which are installed in the hydraulic circuit to achieve precise adjustment of hydraulic power assistance and real-time monitoring of the circuit status.

[0006] Preferably, the road surface adhesion coefficient detection module is configured to: obtain an estimated value of the road surface adhesion coefficient from the electronic stability program system, and output data using a preset road surface adhesion coefficient value when data acquisition fails.

[0007] Preferably, the hydraulic accumulator is configured to store pressurized oil pre-charged by the main electro-hydraulic pump, and to output pressurized oil to the hydraulic circuit synchronously with the main electro-hydraulic pump when the steering wheel torque sensor detects a steering assist demand.

[0008] Preferably, the intelligent main controller is further configured to trigger emergency control logic to drive the auxiliary electro-hydraulic pump to operate at a fixed speed to provide basic hydraulic assistance when the controller local area network bus communication is interrupted or the controller itself fails.

[0009] Preferably, the dual-source redundant hydraulic power unit further includes a hydraulic circuit switching valve group, which is configured to: when abnormal pressure and speed signals of the main electro-hydraulic pump are detected, disconnect the connection between the main electro-hydraulic pump and the hydraulic circuit, and simultaneously open the path between the auxiliary electro-hydraulic pump and the hydraulic circuit, so that the auxiliary electro-hydraulic pump can provide hydraulic power to the hydraulic circuit independently.

[0010] A control method based on the aforementioned electric hydraulic power steering system for new energy vehicles is characterized by being a hierarchical forward-looking matching control method, comprising coordinated control of a fault diagnosis layer, a power steering decision layer, and an energy optimization layer. The specific steps are as follows: Power steering decision layer control: Based on steering wheel torque, vehicle speed, lateral acceleration, remaining battery charge, and road adhesion coefficient information collected by a multi-dimensional working condition sensing unit, adjustment commands are sent to the hydraulic adjustment unit, classifying three hydraulic power steering output specifications: basic power steering, standard power steering, and enhanced power steering. Under the enhanced power steering specification, a proportional solenoid valve is controlled to limit the hydraulic fluid output flow rate, thereby limiting the maximum steering angular velocity; Energy optimization… Layer control: Includes forward-looking energy storage control based on driver steering intention prediction and adaptive pump speed adjustment. Forward-looking energy storage control predicts steering needs based on vehicle speed and steering wheel angle change rate, and controls the main electro-hydraulic pump to charge the hydraulic accumulator in advance. Adaptive pump speed adjustment adjusts the operating speed of the main electro-hydraulic pump based on the pressure detection value of the hydraulic accumulator. Fault diagnosis layer control: By collecting data on the main electro-hydraulic pump motor speed, auxiliary electro-hydraulic pump motor speed, hydraulic circuit pressure, circuit flow, and motor winding temperature, fault identification is performed using multi-parameter deviation threshold judgment and continuous sampling verification. When a fault is identified, action commands are issued to the corresponding switching and control components.

[0011] Preferably, the driver's steering intention prediction adopts a multi-parameter fusion judgment logic, which integrates the detection values ​​of three parameters—steering wheel torque change rate, steering wheel angle change rate, and vehicle speed—with the comparison results of preset thresholds. The preset thresholds can be adaptively adjusted according to the driver's steering habits and driving conditions, and a misjudgment correction mechanism is provided: when the predicted steering demand is not confirmed by the actual steering operation within a preset time, the forward charging control is canceled and the system is restored to the state before the prediction.

[0012] Preferably, the threshold values ​​for the three hydraulic power assist output specifications are determined through actual vehicle calibration. Specifically, the criteria for the basic power assist specification are: battery remaining charge ≤20%, steering wheel torque ≤5 N·m, or parking state, with the main electro-hydraulic pump controlled at idle speed for charging and the hydraulic accumulator not outputting; the criteria for the standard power assist specification are: battery remaining charge 20%-80%, road surface adhesion coefficient ≥0.6, with the main electro-hydraulic pump controlled at normal speed and the hydraulic accumulator outputting as needed; and the criteria for the enhanced power assist specification are: battery remaining charge ≥80%, road surface adhesion coefficient <0.6, and lateral acceleration ≥2 m / s². 2Furthermore, the steering wheel torque is ≥20 N·m, the main electro-hydraulic pump is controlled to run at full speed, the hydraulic accumulator outputs full capacity and limits the oil output flow.

[0013] Preferably, the specific steps of the adaptive adjustment of the pump speed are as follows: when the pressure detection value of the hydraulic accumulator reaches the upper limit threshold for charging, the main electro-hydraulic pump is controlled to automatically reduce its speed to idle speed; when the pressure detection value drops to the lower limit threshold for release, the main electro-hydraulic pump is controlled to start and increase to the charging speed; when the remaining battery charge detection value is lower than the preset threshold, the main electro-hydraulic pump is controlled to run at a limited low speed.

[0014] Preferably, the specific rule for determining the multi-parameter deviation threshold is as follows: compare the real-time collected value of each parameter with the corresponding normal working range; if it exceeds the range, it is recorded as a single deviation; if the number of deviations in continuous sampling reaches a preset value, it is determined as a fault.

[0015] The beneficial effects of this technical solution compared with the prior art are as follows: (1) This technical solution solves the inherent contradiction between energy consumption, response and safety of traditional systems by setting up a dual-source energy storage hydraulic power unit consisting of a main electro-hydraulic pump, an auxiliary electro-hydraulic pump connected in parallel and a hydraulic accumulator connected in series, and cooperating with the hierarchical look-ahead matching control method executed by the intelligent main controller. Among them, the hydraulic accumulator, as a fast response source of high-pressure oil, can release oil instantly when steering demand occurs after the main pump is pre-charged, and output synchronously with the main pump, thereby eliminating the power assist delay. At the same time, the main pump does not need to maintain high speed standby. Combined with the adaptive adjustment of pump speed, the system operating power consumption is reduced. The redundant parallel architecture of the main and auxiliary pumps provides power backup for the system in case of failure, ensuring high reliability.

[0016] (2) By setting up a multi-dimensional working condition perception unit including a battery remaining power detection module and a road surface adhesion coefficient detection module, and cooperating with the power assist decision layer control based on multi-dimensional information executed by the intelligent main controller, a deep intelligent integration of the steering system with the vehicle status and driving environment is achieved. Among them, the battery remaining power detection module enables the system to perceive the energy status of the vehicle, thereby actively limiting the power assist power consumption and optimizing energy distribution when the battery is low; the road surface adhesion coefficient detection module, by acquiring road conditions, enables the system to actively limit the steering angular velocity by controlling the proportional solenoid valve to limit the power assist fluid flow under dangerous working conditions such as low-adhesion roads, thereby providing sufficient power assist while preventing vehicle sideslip and improving active safety.

[0017] (3) By setting up redundant communication interfaces for dual-controller LAN bus channels, emergency control logic, and hydraulic circuit switching valve groups, and in conjunction with the multi-parameter collaborative diagnosis mechanism of the fault diagnosis layer, a multi-level and highly robust system safety assurance system was constructed. Dual CAN channel redundancy ensures the reliability of the communication link; the emergency control logic can drive the auxiliary pump to provide basic assistance when the main controller fails; the hydraulic circuit switching valve group can quickly switch the power source when the main pump fails. The fault diagnosis layer accurately identifies faults and reduces false alarms through multi-parameter deviation thresholds and continuous sampling verification. These settings work together to ensure that the system can maintain a minimum level of safe steering function even when single-point or multi-point failures occur in key links such as sensors, communication, controllers, and actuators, thereby improving the functional safety level of the entire vehicle. Attached Figure Description

[0018] Figure 1 is a block diagram of the overall system structure of the present invention; Figure 2 is a schematic diagram of the hydraulic circuit of the present invention; Figure 3 is a flowchart of the control method of the present invention. The following detailed description of the invention, in conjunction with the accompanying drawings and embodiments, illustrates a new energy vehicle electric hydraulic power steering system, as shown in Figures 1-2. This system includes a steering gear, hydraulic oil pipes, a reservoir, a multi-dimensional operating condition sensing unit, a dual-source redundant hydraulic power unit, an intelligent main controller, and a hydraulic adjustment unit. The dual-source redundant hydraulic power unit and the reservoir form a hydraulic circuit with the steering gear via hydraulic oil pipes. All units are connected via a controller local area network bus and hydraulic oil pipes, constituting a complete mechatronic integrated system.

[0019] The multi-dimensional working condition perception unit includes a steering wheel torque sensor, a vehicle speed sensor, a lateral acceleration sensor, a battery remaining power detection module, and a road surface adhesion coefficient detection module.

[0020] The steering wheel torque sensor, vehicle speed sensor, lateral acceleration sensor, and battery remaining power detection module are all mature vehicle sensors that can be directly purchased or integrated. Their signals are connected to the system through a dedicated analog-to-digital conversion circuit or directly through the controller area network bus.

[0021] The road adhesion coefficient detection module is physically a CAN communication processing chip and supporting program integrated on the intelligent main controller circuit board, logically belonging to the multi-dimensional working condition perception unit. This module is configured to periodically (e.g., every 10ms) send data request frames to the electronic stability program system or listen to its broadcast frames via the vehicle's controller area network (MAN) bus to obtain its real-time estimated road adhesion coefficient value. The module continuously monitors the bus communication status. If no valid response is received for a predetermined number of consecutive times (e.g., 5 times, corresponding to 50ms), it is determined as a "data acquisition failure." At this time, the module's internal logic switches to a preset default value (e.g., 0.8 for dry roads, 0.5 for wet roads, and 0.2 for icy roads) as its output, i.e., using the preset road adhesion coefficient value for data output. The failure status flag is sent to the vehicle's instrument panel via the bus for alarm purposes.

[0022] The dual-source redundant hydraulic power unit includes a main electro-hydraulic pump, an auxiliary electro-hydraulic pump, a dual-winding switching controller, a hydraulic circuit switching valve group, and a hydraulic accumulator. The inlets of both the main and auxiliary electro-hydraulic pumps are connected to a storage tank via hydraulic lines, and their outlets are connected to the hydraulic circuit in parallel via hydraulic lines. The hydraulic accumulator is connected in series with the outlet of the main electro-hydraulic pump via hydraulic lines to store the pressurized hydraulic fluid pre-charged by the main electro-hydraulic pump.

[0023] The hydraulic circuit switching valve assembly is located at the junction of the main electro-hydraulic pump branch, the auxiliary electro-hydraulic pump branch, and the downstream hydraulic regulating unit. This valve assembly is a hydraulic integrated block that combines a solenoid directional valve and a check valve, and includes at least three main ports: the first port connects to the outlet of the main electro-hydraulic pump and the hydraulic accumulator connected in series; the second port connects to the outlet of the auxiliary electro-hydraulic pump; and the third port connects to the inlet of the downstream hydraulic regulating unit.

[0024] Under normal operating conditions, the solenoid directional valve inside the valve assembly is in the first operating position, connecting the first and third ports (i.e., connecting the main electro-hydraulic pump / hydraulic accumulator branch to the downstream circuit) while simultaneously blocking the second port (i.e., the auxiliary electro-hydraulic pump branch). When the dual-winding switching controller determines a fault based on detected abnormal pressure and speed signals of the main electro-hydraulic pump, it sends a switching control signal to the solenoid directional valve of the valve assembly. The solenoid directional valve switches to the second operating position. In this position, the valve assembly cuts off the connection between the first and third ports (i.e., disconnecting the main electro-hydraulic pump from the hydraulic circuit), while simultaneously connecting the second and third ports (i.e., connecting the auxiliary electro-hydraulic pump to the hydraulic circuit), thus enabling the auxiliary electro-hydraulic pump to provide hydraulic power to the hydraulic circuit independently. A check valve within the valve assembly prevents backflow of hydraulic fluid.

[0025] The hydraulic regulating unit includes a proportional solenoid valve, a pressure sensor, and a flow sensor. The proportional solenoid valve is connected in series on the main pipeline between the output of the hydraulic circuit switching valve assembly and the steering gear inlet. The pressure sensor's detection point is located at the outlet of the hydraulic circuit switching valve assembly or a relevant high-pressure node to monitor the system supply pressure. The flow sensor is connected in series in the outlet pipeline of the proportional solenoid valve to directly monitor the actual power steering fluid flow rate. The analog signals from both are connected to the analog input port of the intelligent main controller, providing real-time data for fault diagnosis, closed-loop control, and condition monitoring.

[0026] The intelligent main controller is an electronic control unit dedicated to power steering control. Its core hardware is built upon a high-performance microcontroller compliant with automotive-grade standards. This microcontroller includes a central processing unit, a clock module, an interrupt controller, and non-volatile memory (such as flash memory) and volatile memory (such as random access memory) for storing programs and data. Surrounding this microcontroller, the intelligent main controller also includes the following key peripheral circuits: Communication interface circuit: This includes a dual-controller LAN bus channel redundant communication interface. This circuit contains two independent bus transceivers and physical layer interfaces, respectively connected to different network branches of the vehicle, and ultimately merging into the microcontroller's two independent communication modules, achieving hardware redundancy in the communication path.

[0027] Sensor signal conditioning and acquisition circuit: used to receive analog signals from pressure sensors and flow sensors in the hydraulic regulating unit, and to perform filtering, amplification and analog-to-digital conversion.

[0028] Power drive and output circuit: including a three-phase inverter bridge drive circuit for driving the motors in the main electro-hydraulic pump and the auxiliary electro-hydraulic pump, and a current drive circuit for precisely controlling the proportional solenoid valve.

[0029] Digital input / output interface: used to receive switching signals and control solenoid valves in dual-winding switching controllers and hydraulic circuit switching valve groups.

[0030] Power management and monitoring circuit: Provides a stable and isolated power supply for the entire controller and integrates monitoring units such as hardware watchdog timers.

[0031] The intelligent main controller's software system adopts a multi-task scheduling architecture based on a fixed time period. The operating programs stored in its non-volatile memory are configured to implement a hierarchical look-ahead matching control method. This control logic specifically consists of three parts: collaborative fault diagnosis, decision assistance, and energy optimization. Its implementation is as follows: Data reception and fusion: In each control cycle, the microcontroller actively reads steering wheel torque, vehicle speed, lateral acceleration, remaining battery charge, and road adhesion coefficient data reported by the multi-dimensional condition sensing unit from the vehicle network via its dual-controller LAN bus channel. Simultaneously, it reads relevant status information from the battery management system and the vehicle controller. All data undergoes validity verification and data fusion processing to form a unified system status view for the current moment.

[0032] Layered Algorithm Execution: Based on the fused system state data, the microcontroller executes three layers of core control logic sequentially or in parallel within the same control cycle: Fault Diagnosis Logic: This logic identifies faults by collecting data on the main electro-hydraulic pump motor speed, auxiliary electro-hydraulic pump motor speed, hydraulic circuit pressure, circuit flow rate, and motor winding temperature, using multi-parameter deviation threshold judgment and continuous sampling verification. Specifically, the real-time collected values ​​of each parameter are compared with the pre-stored corresponding normal operating range; deviations exceeding the range are recorded as single deviations. In continuous sampling, if the cumulative number of deviations for a certain parameter reaches a preset value, the component or related circuit is determined to be faulty. When a fault is identified, action commands are immediately issued to the corresponding switching and control components.

[0033] Assist Decision Logic: This logic, based on information collected by the multi-dimensional working condition sensing unit, including steering wheel torque, vehicle speed, lateral acceleration, remaining battery charge, and road adhesion coefficient, sends adjustment commands to the hydraulic adjustment unit. Its core decision rule is to divide the system into three levels of assist modes, determined through real-vehicle calibration: Basic Assist Mode: Triggered when remaining battery charge is ≤20% and (steering wheel torque ≤5 N·m or the vehicle is parked). In this mode, the main electro-hydraulic pump operates at idle speed, and the hydraulic accumulator does not output power.

[0034] Standard power assist mode: Triggered when the battery charge is between 20% and 80% and the road surface adhesion coefficient is ≥0.6. In this mode, the main electro-hydraulic pump operates at normal speed, and the hydraulic accumulator outputs power as needed, with the power assist varying linearly with vehicle speed and torque.

[0035] Enhanced assist mode: Triggered when battery remaining charge is ≥80%, road surface adhesion coefficient is <0.6, and lateral acceleration is ≥2m / s². 2 Furthermore, the steering wheel torque is ≥20 N·m. In this mode, the main electro-hydraulic pump operates at full speed, the hydraulic accumulator outputs its full capacity, and the hydraulic fluid output flow is limited by controlling the proportional solenoid valve to limit the maximum steering angular velocity.

[0036] Energy optimization logic: This logic comprises two collaborative components: Proactive energy storage control: This is achieved through driver steering intention prediction. The prediction employs a multi-parameter fusion judgment logic, integrating steering wheel torque change rate, steering wheel angle change rate, and vehicle speed, and comparing them with adaptively adjusted preset thresholds. When an imminent turn is predicted, the main electro-hydraulic pump is preemptively controlled to charge the hydraulic accumulator.

[0037] Adaptive Pump Speed ​​Adjustment: The operating speed of the main electro-hydraulic pump is dynamically adjusted based on the pressure detection value of the hydraulic accumulator. Specifically, when the pressure reaches the upper charging threshold, the main electro-hydraulic pump automatically reduces its speed to idle; when the pressure drops to the lower release threshold, the main electro-hydraulic pump starts and increases to the charging speed. Simultaneously, when the remaining battery charge is below a preset threshold, the maximum operating speed of the main electro-hydraulic pump is limited.

[0038] Control command synthesis and issuance: The output of the three-layer logic is synthesized by the microcontroller to generate the final unified control command set. These commands are converted into specific physical signals through their peripheral circuits: corresponding current commands are output to the proportional solenoid valve drive circuit to achieve power assist adjustment and angular velocity limiting; pulse width modulation signals are output to the inverters of the main / auxiliary electro-hydraulic pumps to control their speed; and digital switching signals are sent to the dual-winding switching controller and the hydraulic circuit switching valve group to execute the switching operation.

[0039] To achieve the highest level of functional safety, the intelligent main controller has a dedicated, high-priority emergency control logic program permanently stored in its protected non-volatile memory area. The triggering and execution mechanism of this logic is as follows: The intelligent main controller continuously performs self-diagnosis and monitoring through two parallel mechanisms: Communication status diagnosis: Real-time monitoring of bus communication quality via its dual-controller LAN bus channels. When communication on all channels is continuously interrupted for more than a preset time (e.g., 500 milliseconds), it is determined to be a communication failure.

[0040] Self-monitoring of operational status: The main program's operational status is continuously monitored through its hardware monitoring circuitry (such as an independent watchdog timer). If the main program crashes or deadlocks, preventing the watchdog timer from being reset periodically, the hardware circuitry will directly generate a reset or interrupt signal.

[0041] When any of the above conditions are met, the system is determined to have entered an extreme fault state of "interruption of controller area network bus communication or failure of itself", and the triggering condition of the emergency control logic is met.

[0042] Once the trigger condition is met, the system's hardware safety mechanisms (such as the reset signal generated by the aforementioned independent watchdog timer) will force the microcontroller to jump and execute the solidified emergency control logic. The core behavior of this logic is configured to completely bypass all the aforementioned conventional data acquisition, fusion, and hierarchical algorithms, directly outputting a pulse-width modulation signal with a fixed duty cycle to the power drive circuit driving the auxiliary electro-hydraulic pump. This fixed signal causes the auxiliary electro-hydraulic pump to operate continuously at a preset, safe speed sufficient to maintain basic steering operations, thereby providing basic hydraulic assistance under any extreme failure conditions and ensuring vehicle controllability.

[0043] As shown in Figure 3, the control method for an electric hydraulic power steering system in a new energy vehicle is a hierarchical look-ahead matching control method, which is executed cyclically in the intelligent main controller at a fixed time period (e.g., a main period of 10ms). This method achieves coordinated fault diagnosis, power steering decision-making, and energy optimization through parallel logic layers.

[0044] The control threshold calibration method uses various thresholds for decision-making and judgment in the control method, including but not limited to the steering wheel torque threshold (5 N·m and 20 N·m), the remaining battery charge threshold (20% and 80%), the road surface adhesion coefficient threshold (0.6), the lateral acceleration threshold (2 m / s²), and the upper and lower pressure limits of the hydraulic accumulator, all of which are determined through a systematic real-vehicle calibration process.

[0045] The calibration process is as follows: On the target vehicle model, multiple drivers with different driving habits conduct extensive real-vehicle tests covering various road surface adhesion conditions such as dry, wet, and icy / snowy conditions, as well as typical driving conditions including urban driving, highway driving, cornering, and parking. During the tests, raw data from all relevant sensors are collected simultaneously and at high frequency, and the drivers' subjective evaluations of steering feel ease, vehicle stability, and system noise are recorded. Subsequently, the massive amount of collected data is processed and analyzed offline. Statistical analysis (such as data clustering analysis based on steering intention recognition, and probability distribution statistics of parameters under various conditions) and multi-objective optimization algorithms (such as genetic algorithms or particle swarm optimization algorithms) are used to inversely solve for an optimal set of threshold parameters, taking steering ease, vehicle handling stability, optimal system energy consumption, and driver subjective satisfaction as comprehensive optimization objectives. Finally, this verified set of thresholds is stored in the non-volatile memory of the intelligent main controller in the form of a two-dimensional or three-dimensional data mapping table, serving as the judgment benchmark for real-time control.

[0046] The specific execution process of hierarchical control: 1. Assisting decision-making layer control: This layer is the control layer that interacts most directly with the driver and operates stably with a medium cycle (e.g., 10 milliseconds).

[0047] Decision input: Its decision-making directly relies on the latest multi-dimensional operating condition perception data that has been fused and processed.

[0048] Mode Mapping and Output: This layer serves as the online application terminal for the calibration results. It maps the current system state to the calibrated three-dimensional assist characteristic data table in real time, thereby determining the specific assist mode (basic, standard, enhanced) and the precise target assist torque value.

[0049] Safety intervention: Based on the real-time calculated safety boundary, a flow-limiting command for the proportional solenoid valve is dynamically output, which is directly converted into a hardware limit on the maximum angular velocity of the steering system.

[0050] 2. Energy Optimization Layer: This layer aims to optimize system energy efficiency and response speed. It contains two parallel closed-loop subprocesses with an operating cycle that is comparable to or slightly faster than the decision layer (e.g., 10 milliseconds).

[0051] Proactive energy storage control: This process involves the closed-loop execution of a predictive algorithm on a real vehicle. It continuously calculates steering wheel operation characteristic parameters and uses adaptive thresholds finely adjusted based on historical data to determine intent. Its core output is a Boolean value (charge or not) and the corresponding target RPM increment for the main pump. This process is independent of whether the driver has begun heavy steering.

[0052] Adaptive pump speed regulation: This process is based on closed-loop regulation of hydraulic accumulator pressure. It monitors the pressure at a faster frequency (e.g., 5 milliseconds) and generates a main pump speed regulation command to maintain the accumulator's optimal operating window based on calibrated upper and lower pressure thresholds. This process is also strongly coupled with the vehicle's state of energy; when a low-charge status signal is received from the battery management system, it actively overrides and limits the upper limit of the speed command.

[0053] 3. The fault diagnosis layer controls this layer to run at the highest execution frequency (e.g., 5 milliseconds or higher) and priority.

[0054] Real-time monitoring: Directly access the signals from the lowest-level sensors and drivers for high-frequency synchronous acquisition.

[0055] Online diagnostics: Applying reliable multi-parameter deviation thresholds and continuous sampling rules, rapid fault identification is performed within a time window.

[0056] Safe takeover: Once a fault is confirmed, this layer has the highest priority and can immediately interrupt the normal command output of other layers. It can also send direct, unmodified switching or shutdown commands to the underlying safety hardware such as dual-winding switching controllers and hydraulic circuit switching valve groups to ensure that the safety response delay is minimized.

[0057] The decision-making layer provides the "goal," the energy optimization layer provides the "strategy for efficiently achieving the goal," and the fault diagnosis layer provides the "monitoring to ensure the safe achievement of the goal." Finally, the intelligent main controller arbitrates and merges the output commands from these three layers to generate a unified, coordinated, and safe set of final execution commands to drive the hydraulic system.

[0058] The specific implementation process is as follows: After the vehicle is powered on and the system completes its self-test, it enters standby mode, and the main electro-hydraulic pump starts to pre-charge the hydraulic accumulator. When the driver begins to operate, the vehicle status and the driver's intentions are captured in real time by the multi-dimensional working condition sensing unit and transmitted to the intelligent main controller via the controller area network bus.

[0059] The intelligent main controller acts as the command center, coordinating the parallel operation of each dedicated control layer according to the hierarchical forward matching control method: the assistance decision layer maps precise assistance needs based on real-time operating conditions; the energy optimization layer simultaneously manages energy consumption and accelerates response; and the fault diagnosis layer performs uninterrupted safety inspections with the highest priority.

[0060] The controller integrates the outputs from each layer to generate coordinated control commands, precisely driving the dual-source redundant hydraulic power unit and hydraulic regulation unit: by adjusting the speed of the electro-hydraulic pump and the opening of the proportional solenoid valve, and combining the rapid energy throughput of the hydraulic accumulator, it provides the driver with responsive, smooth-feeling, and energy-optimized steering assistance.

[0061] Throughout the entire work cycle, the fault diagnosis layer maintains the highest alert level. Once it determines that any abnormality has occurred in the system based on the multi-parameter collaborative diagnosis mechanism, it will immediately trigger the preset hardware redundancy switch or execute the fixed emergency control logic to ensure that the system can maintain basic power steering function under any fault conditions, thus ensuring the vehicle's minimum risk handling status.

[0062] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An electric hydraulic power steering system for new energy vehicles, characterized in that: The system includes a steering gear, hydraulic lines, a reservoir, a multi-dimensional operating condition sensing unit, a dual-source redundant hydraulic power unit, an intelligent main controller, and a hydraulic adjustment unit. The dual-source redundant hydraulic power unit and the reservoir form a hydraulic circuit with the steering gear via hydraulic lines. The multi-dimensional operating condition sensing unit includes a steering wheel torque sensor, a vehicle speed sensor, a lateral acceleration sensor, a battery remaining power detection module, and a road surface adhesion coefficient detection module. The road surface adhesion coefficient detection module communicates with the vehicle's electronic stability program system via a controller area network bus to obtain an estimated road surface adhesion coefficient. All sensors and detection modules communicate bidirectionally with the intelligent main controller via the controller area network bus to collect real-time data on vehicle driving and steering requirements. The dual-source redundant hydraulic power unit includes a main electro-hydraulic pump, an auxiliary electro-hydraulic pump, a dual-winding switching controller, and a hydraulic accumulator. The main electro-hydraulic pump and the auxiliary electro-hydraulic pump are connected in parallel to the hydraulic circuit. The hydraulic accumulator is connected in series with the outlet of the main electro-hydraulic pump to store high-pressure hydraulic fluid and quickly replenish it. The main electro-hydraulic pump is driven by a high-pressure, high-flow permanent magnet synchronous motor, and the auxiliary electro-hydraulic pump is driven by a low-pressure, low-flow brushless DC motor. The intelligent main controller is configured to execute control logic for fault diagnosis, power-assisted decision-making, and energy optimization, and is equipped with a dual-controller local area network bus channel redundant communication interface. The intelligent main controller communicates with the multi-dimensional operating condition sensing unit, the dual-source redundant hydraulic power unit, the vehicle controller, and the battery management system, and is configured to receive multi-dimensional operating condition data, issue control commands, and execute corresponding control methods. The hydraulic adjustment unit includes a proportional solenoid valve, a pressure sensor, and a flow sensor, which are installed in the hydraulic circuit to achieve precise adjustment of hydraulic power assistance and real-time monitoring of the circuit status.

2. The electric hydraulic power steering system for new energy vehicles as described in claim 1, characterized in that: The road surface adhesion coefficient detection module is configured to: obtain the estimated value of the road surface adhesion coefficient from the electronic stability program system; and output the data using a preset road surface adhesion coefficient value when data acquisition fails.

3. The electric hydraulic power steering system for new energy vehicles as described in claim 1, characterized in that: The hydraulic accumulator is configured to store pressurized oil pre-charged by the main electro-hydraulic pump, and to output pressurized oil to the hydraulic circuit synchronously with the main electro-hydraulic pump when the steering wheel torque sensor detects a steering assist demand.

4. The electric hydraulic power steering system for new energy vehicles as described in claim 1, characterized in that: The intelligent main controller is also configured to trigger emergency control logic to drive the auxiliary electro-hydraulic pump to operate at a fixed speed to provide basic hydraulic assistance when the controller local area network bus communication is interrupted or the controller itself fails.

5. The electric hydraulic power steering system for new energy vehicles as described in claim 1, characterized in that: The dual-source redundant hydraulic power unit also includes a hydraulic circuit switching valve group, which is configured to: when abnormal pressure and speed signals of the main electro-hydraulic pump are detected, disconnect the connection between the main electro-hydraulic pump and the hydraulic circuit, and simultaneously open the path between the auxiliary electro-hydraulic pump and the hydraulic circuit, so that the auxiliary electro-hydraulic pump can provide hydraulic power to the hydraulic circuit independently.

6. A control method for the electric hydraulic power steering system of new energy vehicles according to claims 1-5, characterized in that, The control method is a hierarchical look-ahead matching control method, including collaborative control of a fault diagnosis layer, a power assist decision layer, and an energy optimization layer. The specific steps are as follows: Power Assist Decision Layer Control: Based on steering wheel torque, vehicle speed, lateral acceleration, remaining battery charge, and road adhesion coefficient information collected by the multi-dimensional working condition perception unit, adjustment commands are sent to the hydraulic adjustment unit to classify three hydraulic power assist output specifications: basic power assist, standard power assist, and enhanced power assist. Under the enhanced power assist specification, the proportional solenoid valve is controlled to limit the hydraulic fluid output flow to limit the maximum steering angular velocity. Energy Optimization Layer Control: Includes control based on driver steering intention prediction. The system employs a forward-looking energy storage control and pump speed adaptive adjustment mechanism. Forward-looking energy storage control involves predicting steering demand based on vehicle speed and steering wheel angle change rate, and proactively controlling the main electro-hydraulic pump to fill the hydraulic accumulator. Adaptive pump speed adjustment adjusts the main electro-hydraulic pump's operating speed based on the hydraulic accumulator's pressure detection value. Fault diagnosis layer control involves collecting data on the main electro-hydraulic pump motor speed, auxiliary electro-hydraulic pump motor speed, hydraulic circuit pressure, circuit flow rate, and motor winding temperature. Fault identification is performed using multi-parameter deviation threshold judgment and continuous sampling verification. The identification result sends action commands to the corresponding switching and control components when a fault occurs.

7. The control method for an electric hydraulic power steering system for new energy vehicles as described in claim 6, characterized in that: The driver steering intention prediction adopts a multi-parameter fusion judgment logic, which integrates the detection values ​​of three parameters—steering wheel torque change rate, steering wheel angle change rate, and vehicle speed—with the comparison results of preset thresholds. The preset thresholds can be adaptively adjusted according to the driver's steering habits and driving conditions, and a misjudgment correction mechanism is set up: when the predicted steering demand is not confirmed by the actual steering operation within a preset time, the forward charging control is canceled and the system is restored to the state before the prediction.

8. The control method for an electric hydraulic power steering system for new energy vehicles as described in claim 6, characterized in that: The threshold values ​​for the three hydraulic power assist output specifications were determined through actual vehicle calibration. Specifically: the basic power assist specification is determined when the remaining battery charge is ≤20%, the steering wheel torque is ≤5 N·m, or the vehicle is in a parked state, with the main electro-hydraulic pump idling and the hydraulic accumulator not outputting fluid; the standard power assist specification is determined when the remaining battery charge is 20%-80%, the road surface adhesion coefficient is ≥0.6, the main electro-hydraulic pump operates at normal speed, and the hydraulic accumulator outputs fluid as needed; the enhanced power assist specification is determined when the remaining battery charge is ≥80%, the road surface adhesion coefficient is <0.6, and the lateral acceleration is ≥2 m / s². 2 Furthermore, the steering wheel torque is ≥20 N·m, the main electro-hydraulic pump is controlled to run at full speed, the hydraulic accumulator outputs full capacity and limits the oil output flow.

9. The control method for an electric hydraulic power steering system for new energy vehicles as described in claim 6, characterized in that, The specific steps of the adaptive adjustment of the pump speed are as follows: when the pressure detection value of the hydraulic accumulator reaches the upper limit threshold of charging, the main electro-hydraulic pump is controlled to automatically reduce its speed to idle speed; when the pressure detection value drops to the lower limit threshold of release, the main electro-hydraulic pump is controlled to start and increase to the charging speed; when the remaining battery charge detection value is lower than the preset threshold, the main electro-hydraulic pump is controlled to run at a limited low speed.

10. The control method for an electric hydraulic power steering system for new energy vehicles as described in claim 6, characterized in that: The specific rules for determining the multi-parameter deviation threshold are as follows: compare the real-time collected values ​​of each parameter with the corresponding normal working range. If the value exceeds the range, it is recorded as a single deviation. If the number of deviations in continuous sampling reaches a preset value, it is determined as a fault.

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