1. Overview of the functions of the new energy vehicle controller VCU:
Pure electric vehicle vehicle controller VCU, an excellent, reliable and versatile VCU is a huge system project, it is not just the development (or selection) of VCU hardware and software writing, more importantly, the entire High integration and matching of core components (motor, battery, etc.) in the powertrain, otherwise the performance, safety and reliability of the vehicle will be compromised.
As the core component of new energy vehicles, VCU is responsible for the energy distribution management of the whole vehicle, including torque management, motor battery coordination management, charging management and fault diagnosis, etc.; according to the collection of driver's operation instructions, vehicle speed, drive motor speed, SOC and water temperature, etc. parameters, select the best energy output mode of the new energy vehicle, and achieve the established optimal matching goal of the motor, battery and transmission system. Therefore, a high-performance, low-cost VCU has a very important impact on the power, economy, safety and other vehicle performance of new energy vehicles.
2. VCU development process:
The VCU development process is implemented in stages according to the V process development model. In the VCU software development process, the development process and development tools are one of the important means to ensure the quality of the developed software. All aspects of the development process, from the previous requirements analysis, software system design, software design, code implementation and hardware matching, hardware-in-the-loop (HiL) simulation test, etc., need to borrow professional tools to improve development efficiency and ensure development quality.
V-shaped development process
1) Requirements analysis: Requirements analysis is based on the design goals and configuration reference information to complete the vehicle controller requirements analysis and determine the functional logic, functions and performance indicators that the vehicle controller needs to achieve. Then, according to the functional requirements document, formulate the functional definition of the vehicle controller and the functional requirements document of the pure electric vehicle vehicle controller.
2) System design: Software developers design software function detailed documents according to functional requirements documents; testers design system test specification documents according to functional requirements documents.
3) Software design: Software developers build the control algorithm models of each module according to the detailed description documents of the software functions of each module.
4) MiL test: Testers design MiL unit test cases for each module according to the detailed description documents of the software functions of each module, testers execute MiL unit tests, and output test reports.
5) HiL test: Testers design HiL test cases according to the system test specification documents, edit HiL test sequences according to HiL test cases, load test sequences through HiL test management software, execute tests, and output test reports.
6) Bench test: Bench integration test includes power-on and basic initialization calibration, system function test and calibration under various working conditions, control algorithm verification/test, test result analysis and evaluation, test data sorting, and test report writing;
7) Real vehicle test: Carry out VCU calibration and functional verification test on the functional prototype vehicle.
3. Software architecture:
VCU software development adopts task modularization, formulates clear boundaries and interfaces for each task module, and conducts simultaneous and independent development. The VCU software adopts standard application layer interface requirements, layered application layer, interface layer, and basic software layer.
VCU software architecture specification
The standardized VCU software includes the following three layers:
1) The top ASW (Application SofeWare), namely the application layer software components. The ASW layer is a software module divided on the basis of function, and has a standardized standard interface. A standard ASW has the following characteristics: independent of the type of microcontroller it will be mapped into; independent of the type of target controller; independent of other ASW modules communicating with it. In this way, software developers can focus on algorithm research when developing upper-level software, without having to spend a lot of energy on the underlying algorithm and underlying drivers, as well as the stitching between algorithmic software modules. ASW application layer software development is the key work content of this project;
2) The bottom BSW (Basic Software), that is, basic software. Simply put, the basic software layer mainly includes controller-related underlying drivers and real-time operating systems. AUTOSAR has also made detailed regulations on the writing of these underlying software, including interface definition, function type division, etc.;
3) Between the upper-level software components and the lower-level basic software, there is a layer called RTE (Real Time Environment), which is the level of the real-time operating environment. The connection between the software components and between the upper layer software components and the bottom layer basic software is established through a standardized interface, so that each independent software module is linked into a software application of a specific controller.
4. Control function:
The VCU has functions such as vehicle torque management, battery energy coordination management, motor power coordination management, charging management, and fault diagnosis. It can manage the high/low voltage control logic when the power is turned on/off, can make accurate judgment on the demand torque according to the driver's input, can judge the current working condition of the vehicle, and can realize the functions of torque request and torque limit; it can realize Regenerative braking function, and coordinate the braking energy recovery process of motor braking and ABS system to ensure braking safety; it can identify component and system function failures, and adopt corresponding countermeasures to provide a limp function under system failure protection.
1) Input signal processing: VCU realizes the processing of collected physical signals and received CAN signals.
- Collection interface settings
- data analysis
- Data filtering
- Switch anti-shake
- Judgment of the authenticity of physical signals
- For signal input processing, it is mainly divided into four types: digital input signal, analog input signal, pulse input signal and CAN bus receiving signal; the input signal processing module is based on the collected hard line signal or received bus signal according to the signal type Perform filtering, anti-shaking, hysteresis and other processing on the corresponding signal, and diagnose and process the signal to prevent signal distortion and ensure the validity and reliability of the signal. For CAN bus receiving signals, it is necessary to detect the frame loss and disconnection of the received signals according to the signal type to ensure the validity and reliability of signal transmission.
2) Vehicle status monitoring: VCU can accurately identify the status of each electrical appliance of the vehicle according to CAN messages and physical signals.
- Status identification of each vehicle electrical appliance, that is, it is necessary to identify whether each vehicle electrical appliance is working normally (vehicle electrical appliances include but not limited to: DC/DC, battery system, motor system, air conditioner, PTC, compressor, vacuum pump, water pump, fan, P gear motor, etc.)
3) Driving intention recognition: VCU can accurately identify the driver's intention according to the vehicle condition and the driver's operation.
- Key signal recognition (general knob key signal and PEPS signal recognition)
- Slow charging plug gun
- Fast charging charging plug
- Shift intent
- Acceleration intent
- brake intent
- Driving mode switching intent
- steering intent
- Appliance opening and closing intent
- Emergency response intent
4) Torque control: VCU performs vehicle torque control according to the driver's intention and vehicle state.
- VCU should perform demand torque calculation according to driver's intention (acceleration pedal, gear, etc.)
- Drive mode switching intent for demand torque calculation
- VCU shall calculate and control the starting torque of the vehicle
- VCU calculates and controls creep torque
- VCU calculates and controls the standing torque
- VCU performs energy feedback torque calculation and control
- VCU performs constant speed cruise torque calculation and control
- VCU performs torque calculation and control in limp mode
- VCU performs vehicle torque limit
- VCU performs vehicle torque damping treatment
- VCU performs vehicle torque gradient processing
- VCU for torque smoothing
- The torque control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
5) Gear position control: VCU performs vehicle torque control according to the driver's intention and vehicle state.
- Vehicle current gear recognition and prompts
- pattern recognition
- gear fault tolerance
- Gear shift control
- The gear control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
6) Vehicle state recognition and switching control: VCU can accurately identify the state of the vehicle, and perform vehicle state switching control according to the driver's intention and vehicle state.
- VCU can accurately identify whether the low-voltage circuit of the vehicle is closed
- VCU accurately identifies whether the high-voltage circuit of the vehicle is closed
- The VCU should accurately identify whether the vehicle is in the slow charging mode, and be able to accurately identify the slow charging status (not started, completed, charging, charging failure)
- VCU can accurately identify whether the vehicle is in the fast charging mode, and can accurately identify the fast charging status (not started, ended, charging, charging failure)
- VCU can accurately identify whether the vehicle is in creep mode
- VCU can accurately identify whether the vehicle is in regenerative mode
- VCU can accurately identify whether the vehicle is in cruise control mode
- VCU can accurately identify whether the vehicle is in parking mode
- VCU can accurately identify whether the vehicle is in limp mode
- VCU can accurately identify whether the vehicle is in active discharge mode
- VCU can perform switching control of different modes according to the driver's intention and the state of the vehicle (including but not limited to normal driving mode, standby mode, creeping mode, energy feedback mode, cruise control mode, parking mode, charging mode, limp mode, etc.)
- VCU can judge the abnormal state of the operation mode and has countermeasures
- The vehicle state recognition and switching control process will not affect the safety of personnel and vehicles, and consider the user experience to minimize energy consumption.
7) Cruise control: VCU performs cruise control according to the driver's intention and vehicle status.
- Only under the action of the drive motor, the vehicle must be able to stay on a certain slope for a certain period of time
- Slope function can be realized both forward and backward
- The vehicle is stable during parking
- Equipped with the function of exiting the parking slope and smooth slope
- Standing slope control ensures personnel safety and vehicle safety, and considers user experience to minimize energy consumption
8) Slope control: VCU performs slope control according to the driver's intention and vehicle status.
- Only under the action of the drive motor, the vehicle must be able to stay on a certain slope for a certain period of time
- Slope function can be realized both forward and backward
- The vehicle is stable during parking
- Equipped with the function of exiting the parking slope and smooth slope
- The slope control ensures the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
9) Low-speed creep control: VCU performs low-speed creep control according to the driver's intention and vehicle status.
- The vehicle must be in a constant speed range during the low-speed creep process
- Forward and backward two-way control separately
- Smooth transitions into and out of low-speed creep mode
- During the low-speed creeping process, the vehicle will not experience vibration caused by VCU torque control
- Low-speed creep control cannot affect vehicle starting performance
- Low-speed creep control ensures personnel safety and vehicle safety, and considers user experience to minimize energy consumption.
10) Vehicle power on and off control: VCU controls vehicle power on and off according to the driver's intention and vehicle status.
- Vehicle low-voltage circuit power on and off control
- Power on and off control of relevant vehicle-mounted low-voltage electrical appliances
- Vehicle high-voltage circuit power-on and power-on sequence control
- Power on and off control of relevant vehicle-mounted high-voltage electrical appliances
- Power on and off control of vehicle low voltage circuit and high voltage circuit in failure mode
- Motor control enable control
- Vehicle Ready mode judgment
- Power control in emergency mode
- The process of powering on and off the vehicle will not affect the safety of personnel and vehicles, and the user experience is considered to minimize energy consumption.
11) Thermal management: VCU calculates the required heat transfer according to the temperature distribution of cooling objects (battery, motor, radiator, DC/DC, charger, etc.), and controls related devices accordingly.
- VCU monitors the temperature of the cooling object in real time and judges whether thermal management is required
- VCU accurately calculates the heat transfer required by the vehicle according to the temperature distribution of the cooling object, and controls related components such as water pumps accordingly
- VCU realizes dynamic control of fans and other components according to the coolant temperature, and can maintain the temperature in a constant range
- The thermal management process must ensure that the temperature of the relevant objects is in a constant range
- The energy consumption of the power battery should be minimized during the thermal management process
- The hysteresis function is set during the thermal management process to avoid frequent start-up of related electrical appliances to prolong the service life
- The thermal management process does not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
12) Instrument display control: VCU performs instrument display control according to vehicle status and driver's needs.
- Vehicle fault information display
- Basic information display of vehicle driving
- Important information display during charging
13) Limp control: VCU performs limp control according to vehicle status.
- The vehicle is allowed to enter limp mode only when there is a corresponding fault in the vehicle
- According to the fault type, VCU settings have different limp strategies
- The limp process meets the basic needs of vehicle driving (hill climbing, driving speed, etc.)
- Limp torque is handled and limited separately in VCU
- Limping speed will be controlled within a certain range
- The limp control process cannot affect the safety of personnel and vehicles, and needs to consider user experience to minimize energy consumption
14) Parking control in gear: VCU controls parking in gear P according to the driver's intention and vehicle status.
- Recognition of the current P gear status
- Actual parking status recognition
- Parking sensor status and fault identification
- P block fault tolerance
- P shift control
- The P gear parking control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
15) Brake booster control: VCU performs brake booster control according to the driver's intention and vehicle status.
- Monitoring of the current brake assist level
- Judgment of brake assist system failure
- Control of brake booster
- Brake booster failure and failure control
- The brake booster control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
16) Vehicle energy management: VCU performs vehicle energy management according to the driver's intention and vehicle status.
- Energy management of the vehicle in driving mode
- Energy management of the vehicle in charging mode
- Energy management of the vehicle in limp mode
- Energy management of the vehicle in failure mode
- Energy management needs to limit and distribute the energy of power battery and vehicle battery (12V battery)
- Capacity management allocation principles and standard control
- The energy management process does not affect personnel safety and vehicle safety, and considers user experience to minimize energy consumption.
17) Calculation of cruising range: VCU calculates cruising range according to the state of the vehicle.
- Calculation of vehicle energy consumption per 100 kilometers
- Cruising distance calculation
- Vehicle energy consumption per 100 kilometers can be continuously changed
- The mileage value changes continuously
- The calculation of energy consumption per 100 kilometers and cruising range must be as realistic as possible to improve user experience as much as possible
- Constantly corrected accuracy control during mileage calculation.
18) Charging control: VCU performs charging control according to the driver's intention and vehicle status.
- Ability to differentiate and identify slow charging and fast charging modes
- Trigger condition recognition for charging start (recognition of charging plug, remote charging command recognition, scheduled charging command recognition, etc.)
- Control of charging process (control of charging current, etc.)
- Monitoring of the charging process (temperature at the charging connection, etc.)
- Recognition and handling of misoperations such as fast and slow charging while connecting
- Identification of charging faults
- Judgment of charging end
- Handling of charging end
- Charge control complies with GB/T 27930-2015 and GB/T18487.1-2015
- The charging control process will not affect the safety of personnel and vehicles, and the user experience needs to be considered to minimize energy consumption.
19) Energy recovery: VCU controls energy recovery according to the driver's intention and vehicle status.
- VCU judges the energy recovery mode according to the vehicle condition and the driver's intention
- VCU calculates the feedback torque according to the vehicle condition and driver's intention
- VCU needs to ensure smooth operation during energy feedback
- The energy feedback process will not affect the braking performance of the vehicle
- If there are multiple energy feedback methods, the smooth operation of the vehicle can be satisfied when switching between different energy feedback methods
- Smooth operation of the vehicle when entering and exiting energy recovery
- The energy feedback process will not affect the safety of personnel and vehicles, and the user experience needs to be considered to minimize energy consumption.
20) DC/DC control: VCU performs DC/DC control according to the driver's intention and vehicle status.
- Output control of DC/DC work order
- Monitoring and identification of DC/DC working status
- The DC/DC control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
21) VSP control: VCU performs VSP control according to the driver's intention and vehicle status.
- Recognition of driver's intention
- Output of VSP work orders
- Monitoring of VSP working status
- The VSP control process will not affect the safety of personnel and vehicles, and considers the user experience to minimize energy consumption.
22) Cooling water pump control: VCU controls the cooling water pump according to the vehicle status and driver's intention.
- Temperature monitoring of cooling components
- Cooling water pump status monitoring
- Control the cooling water pump according to the needs of the vehicle cooling system (considering factors such as battery thermal management, air conditioning system cooling, etc. that affect the operation of the cooling water pump)
- Coordinated control of multiple cooling water pumps
- Multiple cooling water pump monitoring conditions and start sequence control
- The cooling water pump control process will not affect the safety of personnel, ensure that the service life of the vehicle electrical appliances is not affected, and consider the user experience to minimize energy consumption.
23) Cooling fan control: VCU controls the cooling fan according to the vehicle status and driver's intention.
- Coolant monitoring for different circuits
- Cooling fan status monitoring
- Control the cooling fan according to the needs of the vehicle cooling system (considering factors that affect the cooling fan's work, such as battery thermal management, air conditioning system cooling, etc.)
- The cooling fan control process will not affect the safety of personnel, try to ensure that the service life of the vehicle electrical appliances is not affected, and consider the user experience to minimize energy consumption.
24) Solenoid valve control: VCU controls the solenoid valve according to the vehicle status and driver's intention.
- Monitor the working status of the water pump
- Solenoid valve status monitoring
- Control the solenoid valve according to the needs of the vehicle cooling system (considering factors that affect the operation of the solenoid valve, such as battery thermal management, air conditioning system cooling, etc.)
- Coordinated control of multiple solenoid valves
- The solenoid valve control process will not affect the safety of personnel, try to ensure that the service life of the vehicle electrical appliances is not affected, and consider the user experience to minimize energy consumption.
25) Compressor control: VCU controls the compressor according to the driver's intention and vehicle status.
- Indoor and outdoor temperature status monitoring
- Compressor status monitoring
- Consider the needs of defrosting and defogging
- Control the compressor according to the driver's needs and the needs of the vehicle cooling system (considering factors that affect the compressor's work, such as the use of air conditioners and battery thermal management)
- The compressor control process will not affect the safety of personnel, try to ensure that the service life of the vehicle electrical appliances is not affected, and consider the user experience to minimize energy consumption.
26) PTC control: VCU performs PTC control according to the driver's intention and vehicle status.
- PTC status monitoring
- Charging heating demand processing
- Control the compressor according to the driver's needs and the needs of the vehicle heating system (considering the factors that affect the PTC work, such as the use of air conditioners and battery thermal management)
- The PTC control process will not affect the safety of personnel, try to ensure that the service life of the vehicle electrical appliances is not affected, and consider the user experience to minimize energy consumption.
27) Diagnosis and treatment of vehicle faults: VCU accurately identifies and classifies vehicle faults according to vehicle status and driver intentions: monitoring of control flow of safety-related functions, monitoring of data flow of safety-related functions, diagnosis of vehicle faults, VCU Fault identification and clearing logic, VCU formulates corresponding treatment measures according to the severity and type of faults, so that every fault that occurs can be handled well, VCU provides different limp modes according to fault types and levels, for For faults, the VCU should store relevant fault information in a timely manner, and the fault diagnosis and processing process will not affect the safety of personnel and vehicles, and the user experience needs to be considered to minimize energy consumption.
- Monitoring of the control flow of safety-related functions
- Monitoring of data flow for safety-related functions
- Diagnosis of vehicle faults (the types of faults to be diagnosed can be determined through negotiation between the two parties)
- VCU fault identification and clearing logic
- VCU formulates corresponding treatment measures according to the severity and type of the fault, so that every fault that occurs can be handled well
- VCU provides different limp modes according to fault types and levels
- For the faults that occur, the VCU should store relevant fault information in a timely manner (the types of faults stored can be determined by both parties through negotiation)
- The fault diagnosis and processing process will not affect the safety of personnel and vehicles, and the user experience needs to be considered to minimize energy consumption.
28) Output signal processing: For the signal that needs to be output, the VCU needs to perform output processing on it.
- Physical signal output processing
- CAN message transmission processing
5. Summary:
As the core component of new energy vehicles, VCU has a very important impact on the performance, economy, safety and other vehicle performance of new energy vehicles. Therefore, mastering mature VCU control algorithms is one of the core competitiveness of vehicle manufacturers!
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