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Vehicle axle coupling dynamometer system

The vehicle axle coupling dynamometer test system consists of a mobile low-inertia electric dynamometer, dynamometer driver, battery simulator, electrical control cabinet, measurement sensors, vehicle windward cooling system, traffic real-life simulation system, main control computer, electrical Control cabinet and other components.
The dynamometer can perform speed and torque control to simulate road load. Load simulation methods include: constant torque control, calculated road spectrum simulation, actual road spectrum import, and user-defined load spectrum. The power analyzer measures the current, voltage and power of each energy consumption unit of the tested vehicle, analyzes the energy flow of the vehicle under different operating conditions, and draws the energy spectrum of the entire vehicle. The dynamometer adopts a low-inertia dynamometer, which has extremely high dynamic characteristics and can simulate rapidly changing working conditions and simulate different road models. By integrating into the traffic scene simulation system, real vehicle actions under different road conditions can be truly reproduced, including the driver's operating comfort. The system can also be transformed into a powertrain test system, and the battery simulator can be connected to the powertrain drive to test the powertrain.
Quantity:

1. Test bed system architecture

The vehicle axle coupling dynamometer test system consists of a mobile low-inertia electric dynamometer, dynamometer driver, battery simulator, electrical control cabinet, measurement sensors, vehicle windward cooling system, traffic real-life simulation system, main control computer, electrical Control cabinet and other components.


The dynamometer can perform speed and torque control to simulate road load. Load simulation methods include: constant torque control, calculated road spectrum simulation, actual road spectrum import, and user-defined load spectrum. The power analyzer measures the current, voltage and power of each energy consumption unit of the tested vehicle, analyzes the energy flow of the vehicle under different operating conditions, and draws the energy spectrum of the entire vehicle. The dynamometer adopts a low-inertia dynamometer, which has extremely high dynamic characteristics and can simulate rapidly changing working conditions and simulate different road models. By integrating into the traffic scene simulation system, real vehicle actions under different road conditions can be truly reproduced, including the driver's operating comfort. The system can also be transformed into a powertrain test system, and the battery simulator can be connected to the powertrain drive to test the powertrain.


The shaft coupling dynamometer adopts a flexible design. Each dynamometer adopts a movable mode. The dynamometer and the vehicle hub adopt a quick connection structure, so that the user can quickly and quickly complete the connection between the vehicle and the dynamometer. The dynamometer tray bracket is supported by universal wheels, which can be moved conveniently, and at the same time, it can also simulate the actual steering function.


The flange shaft connected to the wheel hub of the vehicle adopts a hollow structure to minimize the moment of inertia of the shaft system and improve the dynamic response capability of the dynamometer system. A transitional connection flange is designed between the flange and the wheel hub of the vehicle, and the flange also adopts a weight reduction design to reduce the moment of inertia.


2. Shaft coupling dynamometer function

The axle-coupled dynamometer is a flexible test system with a very high degree of freedom. Users can combine tests at will, and can test four-wheel drive and two-wheel drive vehicles, or separate electric drive powertrain tests. The shaft coupling dynamometer adopts a motor with extremely low inertia and uses real-time Ethernet communication control. It has a very high dynamic response speed and can complete the dynamic alternating working condition test of the load. The shaft coupling dynamometer system has the following functions:

1. Vehicle durability test

2. Vehicle energy flow test

3. Vehicle energy consumption test

4. Vehicle acceleration test

5. Vehicle road simulation test

6. Vehicle braking performance test

7. Test of universal characteristics of the whole vehicle

8. Driver in the loop test

9. Vehicle fault detection

10. Development and calibration of vehicle control strategy

11. Vehicle conformance test

12. Vehicle braking energy recovery test

13. Powertrain efficiency test

14. Powertrain speed and torque characteristic test

15. Powertrain temperature rise test

16. Powertrain controller control strategy development verification test

17. Powertrain braking regenerative energy feedback test

18. Powertrain external characteristic test

19. Powertrain development matching optimization test

20. Powertrain performance test and calibration test

21. Efficiency Map Test

22. Accelerated response test

23. Torque response test

24. Durability test of steady-state cyclic loading

3. Selection specifications of shaft coupling dynamometer

4. Technical description of vehicle energy flow test system

Pure electric vehicle driving range test will use Chinese working conditions GB/T 18386 \"Electric Vehicle Energy Consumption and Driving Range Test Method\" standard. It is determined that Chinese working conditions will replace European NEDC working conditions as the test conditions, and will be introduced High and low temperature test procedures.


Vehicle energy flow test:

1) Energy transfer path:

Based on the specific vehicle configuration, working conditions and working mode, the energy is generated and transferred/converted from the power source to the wheel end.

2) Energy transfer efficiency/loss:

In the energy transmission path, there are lossy systems and components, and the corresponding energy consumption form. The quantified energy consumption distribution for energy consumption systems and components.


Data from EPA:


The key points of the vehicle energy flow test are the accuracy of the measurement and the synchronization of the measurement of different energy-consuming components, as well as the authenticity of the vehicle condition simulation.

In order to improve the accuracy of electric energy measurement, it is necessary to configure a high-precision power analyzer and transformer, and use a power analyzer with a high-precision synchronous clock function to synchronously collect and measure the signals of each sensor.


Vehicle energy flow test:

Energy flow analysis of electric vehicles-braking energy recovery:


9. Software System

The software system is mainly divided into the following parts:


★Test management software:Before the test, test basic parameters and related control parameter settings, generate test information files, and be called by the test main control software.

Through the interaction with the real-time control computer during the test, the test process is automatically managed and the specified real-time information is processed.

After the test is completed, test reports, test record retrieval, data post-processing, etc. are generated.


★Real-time control software of test bench:Through the acquisition of closed-loop control sensor information, and through interaction with the test management computer to obtain the upper-level solved control parameters, and do the necessary lower-level calculations, real-time closed-loop control of the speed and torque of the driving and loading motors and other Real-time control of auxiliary facilities.


★Human-computer interaction processing software:A unified human-computer interaction interface that integrates the main information on the same machine; real-time display of test progress, main test data, the status of the test piece and the test bench and other information.


★Test data acquisition and post-processing software:The system provides various mathematical operations of data, including addition, subtraction, multiplication, division, integration, differentiation, maximum value, minimum value, peak value, RMS, average, sum, etc.


All software systems used adopt modular design ideas, with good flexibility and scalability. The main functional modules of the software are: main program framework module, system control module, data acquisition module, data recording module, data analysis module, data display module, communication module, data playback module, print processing module, sensor calibration module, function setting module, Help document module and data post-processing analysis module, etc.

5.1 Main test interface

After the vehicle has undergone the loss calibration and coasting test, the formal test is carried out. At this time, the simulated load of the dynamometer is similar to the road load of the vehicle.



5.2 Calibration of friction loss

Before the user starts to use the device for testing, the device needs an effective friction calibration (the device will only be used if it exceeds a certain speed corresponding to the friction calibration). The user can check the calibration status through the dial control page that displays the calibration status.


Users can perform friction calibration regardless of whether the vehicle is equipped or not, but the system cannot distinguish between equipment friction loss and vehicle loss at this time. Therefore, the user needs to make a new loss calibration for each new car. It is recommended to do friction calibration where the vehicle is not equipped.


At the same time, the user needs to consider that the friction loss will change with the change of the ambient temperature. Therefore, it is necessary to warm up the device before friction calibration or test and maintain its temperature until the end of the test.



5.3 Vehicle loss calibration

When the vehicle loss calibration is completed, the page will automatically update and display the maximum calibration speed. The calibration of friction loss can be analogized to the calibration of vehicle loss. The maximum calibration speed displayed is the lower of the friction calibration speed and the vehicle loss calibration speed.



5.4 Basic inertia calibration

The basic inertia calibration is used to calibrate the basic inertia of the test bench, including: the total moment of inertia of each transmission system such as the drum, drive shaft, and motor. The basic inertia calibration is a necessary condition for the correct operation of the test bench.

5.5 Glide test

In the taxiing process, the system first accelerates the device to above the maximum speed required for taxiing, and then enters the road simulation mode to simulate the road environment until the device is below the minimum speed required for taxiing. When passing the designated speed point, the time at this time Will be recorded. The system can accurately calculate the road simulation by calculating the time and the average deceleration force for the specified taxi distance. Users can find this information on the taxi results page.

5.6 Road load simulation

The system can provide various series of dynamometer electromechanical inertia simulation, and simulate the road load according to the equation:

RL = F0 + F1VX+ F2Vn+ I dv/dt + mg * (Grad/100)

among them:


RL

Road load (road traction)

F0, F1, F2 and n

Road load model coefficient

F0

Friction coefficient independent of speed

F1

Friction coefficient related to speed

F2

Drag coefficient

n

F2The speed index variable (range:1.2—3.0

x

F1The speed index variable (range:0.8—1.2)(If there is)

V

Surface speed of drum

I

Electric analog inertia

dv/dt

Acceleration

m

quality

g

gravity

grad

slope

The parameters F0, F1, F2, n and x (if any) form the road load model, and they can be obtained in a variety of ways


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