NVH Engineering

Based on the software and hardware combination of Siemens Simcenter Test Solution, it cooperates with Siemens and customers to complete the deployment, implementation, training, technical service and technology transfer of the NVH test system.

Case Studies:

Case 1: NVH analysis of hybrid power system

The integration of environmentally friendly hybrid power systems has brought new challenges to NVH engineers. The cylinder pressure of the reduced size internal combustion engine (ICE) will increase, and the high torque fluctuation of the motor will be converted into low-frequency torque vibration, and this vibration will be amplified in the power transmission system. Since mechanical components and system control units will seriously affect the above phenomena, troubleshooting based on virtual models is usually the only feasible way to solve these problems. Model-based systems engineering solutions can help engineers understand and solve NVH problems, as well as achieve balanced integration of hybrid power transmission systems.

The NVH analysis of hybrid integration requires a combination of testing and simulation technology, and is usually used in the vehicle development stage and when there are representation data. If there is a physical prototype, the engineer can first measure the key conditions and find the channels and components that have the greatest impact on the problem. Afterwards, the problem can be reproduced in the 1D simulation model.

Using the above methods can help you evaluate solutions and optimize control strategies in the troubleshooting phase. At the same time, 1D solutions can help you define the best conceptual architecture and achieve a balance between NVH and other functional requirements (such as driving control).

Collecting experimental data stage: The service team uses its rich testing experience to help customers measure the rotational dynamic data of the power transmission system, find out the characteristics of torque and vibration, and build 1D models and verify simulations based on it. At the same time, troubleshooting of the actual vehicle is carried out through modal analysis, operating deflection shapes (ODS) and transmission path analysis (TPA).

Powertrain and vehicle simulation stage: The service team helps customers combine the system model with the vehicle model and the corresponding gearbox, transmission system and controller torque models to build a complete test 1D system model. After gradually optimizing the sub-systems of the vehicle, and adding test results and simplified 3D multi-agent data, the details of the model are more abundant, including accurate descriptions of suspensions, connectors, and flexible components. In order to verify and update the complete system model in each state, the 1D simulation results such as modal, force and acceleration are all related to the test results.

Solution and implementation stage: The service team assists customers in fine-tuning the mechanical system (short-term hardware maintenance) and control strategy (control-based solutions) to reduce the low-frequency torque vibration in the power transmission system, and perform other functional indicators The balance adjustment between. And assist customers to complete the implementation verification and optimization of the solution.

Service results:

Reduce low-frequency torsional vibration in the drivetrain

Combine testing and simulation to determine the root cause of the problem

Use 1D vehicle simulation, including mechanical system and control system

Develop a short-term hardware repair plan or an effective solution based on the control unit

Ensure good functional indicators (such as driving control) while optimizing the NVH response of the power system

Case 2:Electric vehicle motor noise optimization

There are many challenges in developing motors for hybrid vehicles. Engineers need to choose from a large number of motor types and configurations, as well as effectively evaluate all possibilities. In addition to optimizing efficiency through conceptual selection and control strategies, optimizing the motor's NVH performance is also very important. Motors are prone to annoying high-frequency pure noise. By combining electromagnetic guidelines and high-end acoustic radiation research in the same process, the service team can fully optimize its acoustic behavior while keeping the vehicle performance unchanged.

The service team combines testing and simulation methods to help electric vehicle and motor manufacturers and suppliers solve NVH problems in the automotive design stage. In order to calculate motor noise, experts map various forces in electromagnetic simulation to structural finite elements. Model (FEM) to calculate the vibration on the motor housing. The high-end simulation uses the result to calculate the acoustic response of the microphone position.

By combining electromagnetic simulation, structural simulation and acoustic simulation, the service team can effectively evaluate the impact of all possible design changes on NVH, from conceptual design to control strategy and structural changes, all the way to system integration or troubleshooting.

Electromagnetic simulation stage: The service team helps customers use 2D or 3D electromagnetic FEM software to calculate the hysteresis force. By applying current waveforms and describing the phase current using the functional relationship of the rotor angle, speed and torque, the current density and magnetic flux can be calculated, which can be converted into Tangential force and radial force between rotor and stator. The actual current, speed and torque can be calculated by the system-based functional model, which is based on the reference table and motor data such as inertia and loss. This facilitates the design of a control unit that adjusts the phase current.

Vibro-acoustic simulation stage: Experts will mesh and assemble the structural elements of the stator and motor housing in a software environment. At this stage, the correlation between test and simulation and model update are particularly important, because only in this way can the system dynamics in the corresponding frequency range be accurately reproduced. The force calculated according to the 2D/D electromagnetic model will be mapped to the 3D assembly grid to calculate the vibration on the motor housing. These vibration values will be used as boundary conditions in acoustic radiation studies using advanced acoustic FEM technology.

Noise optimization stage: The service team helps customers discover the causes of noise problems and formulate corresponding preventive measures. Collecting all parameters in a continuous process can keep the vehicle performance unchanged while optimizing the noise. The conceptual design, control strategy or structure can also be improved, mainly to ensure that the electromagnetic force does not excessively excite certain structural resonances.

Service results:

Combine electromagnetics and acoustic radiation to implement simulation-based solutions

Reduce motor noise to target level

Avoid pure noise at critical frequencies

Combine testing and simulation to create a validated simulation model

In-depth analysis of the impact of conceptual choices and control strategies on noise behavior

Analyze modifications to the validated simulation model

Management integration issues