The power battery system is a very tight system combined with the hardware body and the control system. The test can be roughly divided into two parts: battery pack body (Pack) test and battery management system (BMS) test. The test conditions of these two parts are respectively introduced below. . metal machine shop
1, battery pack body (Pack) test
Battery pack body testing is typically performed during the DV/PV (design verification/production verification) phase to verify that the design/production of the battery pack meets design requirements. It includes temperature testing, mechanical testing, external environmental simulation testing, low voltage electrical testing, electromagnetic compatibility testing, electrical safety testing, battery performance testing, abuse testing and so on. Because everyone is concerned about battery safety issues, here is a brief introduction to the test method for battery pack abuse test: metal machine shop
1) Acupuncture test
The scene when the analog battery is pierced by a sharp object, because the foreign matter penetrates may cause an internal short circuit, and the test requires no fire and no explosion.
2) Salt water soak
5% saline was immersed for a long time and the battery functioned normally.
At present, the waterproof and dustproof rating of the new energy vehicle battery pack is recommended to be IP67 (ie, 1 meter deep water soak for half an hour without damage, SAIC and Weilai battery packs are all IP67). The car’s use environment is harsh, and it is not too much to do waterproof and dustproof protection (Shanghai has a year of heavy rain that causes the garage to accumulate water, the traditional car is flooded, and the electric car is intact). metal machine shop
3) External fire
The fire was 590 degrees Celsius for 130 seconds without explosion, fire, burning and no flame residue.
1m height free fall on the steel plate, the battery case is fully functional. metal machine shop
5) Vibration test
The high frequency vibration simulation test requires the battery pack to function normally. Colleagues who do battery packs should know that this is also difficult to pass.
2, battery management system (BMS) test
The battery management system test is more focused on software testing, generally in the process of software function development. metal machine shop
Unlike the autopilot system that has not yet been mass-produced, the use of C language for software design is different. Today’s mature electric vehicle control systems (such as vehicle controllers, motor controllers, and battery management systems) are model-based software development. (Model-Based-Design). The advantage of MBD development over C is that it can express complex logic in a graphical way, code readability, portability, and ease of development and debugging. It also utilizes the mature code generation tool chain and avoids manual code. A low-level error that is easy to produce.
Several tests such as MIL/SIL/HIL are specified in the model-based software development process:
1) MIL (Model-In-Loops) is a model-in-the-loop test that verifies whether a software model can implement software functions. The test basis is the software requirements that are decomposed from system requirements.
2) SIL (Software-In-Loops) software in the ring test, the C code generated by the comparison model is consistent with the function implemented by the model itself, and the Sil test can be performed using Simulink’s own tool. metal machine shop
3) The PIL (Processer-In-Loops) processor is in the loop test. The purpose is to test whether the function is implemented to deviate from the model after the code is automatically written to the controller. PIL does not seem to matter, but not paying attention can cause some undesirable consequences (such as scheduling problems, CPU load, stack overflow, etc.).
4) HIL (Hardware-In-Loops) hardware-in-the-loop test, test controller complete system function, generally build the test bench of the system where the controller is located, use electrical components to simulate sensors (such as temperature) and actuators (such as fan load) ) electrical characteristics to verify complete system functionality. metal machine shop
The use cases for these test sessions are derived from system requirements. In the automotive software development process, development and testing into a V-shaped, commonly known as software development V model, interested students can view the automotive software development process ASPICE.
Testing of parts in the extreme environment of the vehicle: The endurance test of the whole vehicle is generally the responsibility of the test & calibration engineer of the OEM. The cost of the endurance test of the whole vehicle is very large. The engineering prototype car (about 1 million per vehicle), the rental test site, and the engineering team spend a lot of money. It is a test of the financial strength of the manufacturer. There is no strong fund pool that cannot be operated at all. However, the more tests performed in extreme environments such as extreme cold, high temperature, and high humidity, the more fully verify the function, performance, and durability of the components, the sooner the problem is discovered, and the lower the cost of repairing the repair. . metal machine shop
1. Low temperature endurance test, mainly testing cold start performance, generally carried out in Heihe / Yakeshi. The low-temperature charge and discharge capacity, low-temperature protection strategy, and battery pack heating function of the battery pack are evaluated in this test.
2. High temperature endurance test, generally carried out in Golmud. Mainly test battery pack charging and discharging capacity at high temperature, battery pack cooling function and overheat protection strategy. The picture below shows Weilai’s high temperature test in Melbourne, Australia. It is not a cost to develop an OEM for the whole vehicle. metal machine shop
3. High-temperature + high-humidity environment durability test, generally carried out in Hainan, the seawater environment will accelerate the corrosion of components, and the durability of the components will withstand the rigorous test. (Ps: There is also an important plateau test for traditional cars, which mainly tests the performance of the engine at low air pressure. Electric vehicles generally do not need this test.)
The better battery pack will promise battery decay during the service life. For example, Weilai ES8 promises to reduce battery capacity by no more than 20% in 300 years and 300,000 kilometers. It is very difficult to do this battery development. . The bold commitment also shows that their battery pack endurance test has achieved a very good level. metal machine shop