Engineers engaged in power management related disciplines have found that once electronic equipment is used for too long or overheated, it will cause loss of some electronic components, performance degradation, and even stop working to cause a safety accident. Are you still doing silly physical analysis during maintenance? This will not only take time to find out the real problem.
Recently, in the "Electronic Technology Design", "Electronic Engineering Album" and "International Electronic Business" jointly held "Power Management and Power Devices Forum" (Tech Shanghai Power 2017), Konmo Digital Corporation (COMSOL) technical manager Wang Gang Dr. Brought a wonderful presentation entitled "Multi-physics Simulation in Power Management and Power Device Devices", explaining several typical examples of "Power Management and Power Device Design", and through these case studies, The key role of simulation in it - very practical!
Dr. Wang Gang pointed out that power management and power devices/equipment involve multiple physics, including:
â—Electronic equipment: current field, magnetic field, semiconductor, electrochemical, etc.
â— Thermal management: forced convection cooling - flow field
â—heat / temperature distribution: temperature field
â— Heat induced stress and deformation
......
"Depending on the various physical fields involved in the device, we can have a lot of words. In addition to experimentation, there is a more convenient tool that is computer simulation, because our software hopes to start from the most basic physical concepts. The numerical calculation method calculates the phenomenon that the power management device will face." Dr. Wang Gang said, "For example, when we study the overheating of the electronic equipment system, we can calculate the power/power device through the related physical concepts such as heat transfer equation or electromagnetic field equation. The time distribution of temperature, and then predict whether performance, life, etc. meet the requirements."
“There is also a concern about electromagnetic pollution. Electromagnetic interference is generated in electromagnetic devices. We need to consider whether these electromagnetic interferences will affect the actual operation of power supplies and power devices. Through simulation tools, we can calculate electromagnetic fields through electromagnetic field calculations. Whether the various parts of interest meet our expectations," he added.
10+ typical user case sharing: Which one fits your design?
Optimizing the design of ABB's smart grid tap-changers with simulation ABB's smart grid tap-changers are used in high-voltage switchgear. After the high-voltage transformer is powered, it is necessary to simulate the dielectric stress on the surface and inside of the insulating material to see if it will damage the structure. Electromagnetic force and dielectric stress are calculated by electromagnetic field calculation. When the strength limit of common materials is known, these calculated forces can be combined to determine whether it will cause unpredictable damage to the switch structure.
Flexible wireless charging with magnetic resonance. For example, Apple released the latest iPhone last week, including wireless charging, which is widely watched. The principle of wireless charging is to generate electromagnetic resonance between the primary coil and the secondary coil to transfer energy. The early design of wireless charging was to keep the two close together, which made electromagnetic resonance very easy. However, we hope that the mobile phone can be placed at any angle or any position on the charging board to achieve electromagnetic resonance. In this case, experimenting will cost a lot. Simulations can be easily modeled by electromagnetic field calculations. “The example in the picture below is the wireless charging simulation solution of WiTricity, USA. This company designs wireless charging for automotive industry equipment or electronic equipment for customers, and analyzes the arrangement or winding of coils and the distance and direction between the master and slave coils. The impact of the simulation. After the simulation, you can quickly do conceptual verification and prototyping to speed up the design process." Dr. Wang revealed.
Graphene effectively improves the performance of consumer electronics. Graphene has excellent heat dissipation properties. With the improvement of its production process, its production will become easier and the application will become more and more extensive in the future. Graphene can be used for heat dissipation in smartphones. The phone space is very narrow, and the graphene is very thin and can be attached to the heat to help dissipate heat. Through numerical calculations, we can determine what graphene design can achieve the best heat dissipation.
The new wiring scheme effectively reduces device heating and mechanical fatigue. ABB's chips and boards are connected by leads. The traditional design scheme is connected by a direct lead wire. Since the pin connection portion is small relative to the area, the contact resistance is large, and a high temperature is generated in actual operation, reaching or exceeding the set limit, resulting in a decrease in lifetime. Therefore, we hope to reduce the temperature by some means in practice. By adding a joint in the middle (the actual machining difficulty has not increased much), ABB has greatly increased the connection area of ​​the pins, thereby greatly improving the heat dissipation performance. The decrease in temperature causes a decrease in thermal stress, which in turn causes the fatigue life of the device switch to increase several times. This can be improved for high reliability product designs.
High-performance power device module optimization design IGBT and other high-power device modules include electrical, magnetic, thermal and other physical fields. The center of the chip may be a hot part. We can find ways to increase the heat dissipation in the center, or in the subsequent optimization design of the heat sink, calculate the heat sink design required outside the module by topology optimization.
The thermal resistance of the SMD design on the board of the simulation chip or the heat of the chip can also be calculated.
Breaking common sense to achieve faster signal simulation speed In the figure below, in the Intel PCB design, we can calculate the best solution for high-speed interconnection through electromagnetic field calculation. Then through the topology optimization algorithm, the antenna automatic wiring and the signal connection method can be calculated.
Battery simulation promotes the development of electric vehicles. Electric vehicle batteries can also obtain better calculation results through simulation. For example, battery simulation calculations made by Ford. By adding a battery module to the simulation tool, you can simulate the operation of the battery. The battery voltage curve in the figure reflects the discharge state when the throttle is depressed and the relaxation process when the throttle is released (the flash point in the figure is the experimental result, and the dotted line is the simulation result; it can be seen that the simulation and the experimental results are basically the same). In addition, we can further simulate the long-term service life of lithium-ion batteries - the battery capacity is considered to be ineffective when it is attenuated to a certain extent.
Improvements in thermal management have dramatically increased battery life. In practice, heat has a significant impact on battery life. This can also be analyzed using simulation software.
The effect of high temperature on the performance of semiconductor devices. The figure below shows a model of a bipolar transistor. If you are designing a semiconductor device, we need to know how to design the device doping and microstructure to meet the semiconductor performance requirements. Therefore, Kang Moxar provides a semiconductor module in the software to calculate the working principle of the semiconductor. Similarly, we can introduce the effects of temperature, voltage, current and other conditions during the simulation to see if the temperature distribution is lower than the specified value. And if you use experimental measurements, you need to place multiple sensors, and it is not as intuitive as the simulation.
Temperature/humidity analysis in semi-closed electronic devices A certain degree of temperature/humidity in an electronic device may cause leakage, which may cause a short circuit. Simulation software can also analyze this.
Simulation App and Simulation Design
Dr. Wang said that the product name of Kang Mouer is COMSOL MulTIphysics. As the name implies, the company is doing multiphysics modeling. The software tools it provides include MULTIPHYSICS and APPLICATIONS. The former is a modeling developer that can create physical models in the same way in software. For example, for power management design, CAD layout can be imported into the model, and then various physical fields such as electromagnetic fields, heat transfer, and fluids can be introduced. Etc., and the calculation results are obtained through modeling. On this basis, further development can be carried out, namely the secondary developer APPLICATIONS. Similar to the app in the smartphone, the secondary developer can easily package the model and get a customized interface. So even for an engineer who doesn't know much about simulation or even simulation, by running on the server or client, he only needs to enter the parameters he cares about in the interface, and he can get the results he wants to know.
The above paragraph sounds a bit abstract, and the following is explained by the actual design.
Simulation App Simplifies the Design of Electronic Devices The following figure is an intuitive interface. APEI's design specifies four leads, automatically draws the graph with a given number, and then calculates the temperature. It can be easily modified on the interface, such as adding leads or reducing leads, filling in the numbers directly on the interface, and clicking on the calculation. This is Kang Mo's “simulation appâ€, and engineers without actual simulation experience can also easily get started.
The same is true for the vertical fin heatsink design app on the PCB. The following picture is an app made by COMSOL's consulting firm AltaSim for its customers.
Thermal Management Simulation App All parameters, geometry, physics, boundary conditions, post-processing, etc. are listed in the simulation interface on the left side of the figure below. This requires simulation experience in operation. It is necessary to understand the concept of simulation. Secondly, it will become more familiar after a period of use, so only a small number of people in each company can be proficient in use. By encapsulating it to get the App form on the right, the user can use it intuitively (only the parameters that need to be fine-tuned, as well as the buttons for calculation, display, etc.), just need to know the usage scenarios of the product.
"In order to simplify the user's use, Kang Mouer provides an app design tool, so that it is very convenient to use the form construction method, such as the control method, to fill the control one by one to package. The user is in his own company or After installing the COMSOL product on the cloud, the above customized simulation app can be uploaded to the COMSOL server through the free client on Windows, or the user can also connect to the server through the browser on the mobile phone to run the simulation and get the desired result. "Dr. Wang said.
“For example, if a customer’s marketing department’s propagandists go to the site to discuss the next product design or correction with their customers, open the tablet or use the mobile phone to connect to the COMSOL Server wirelessly and directly calculate it. Can see if the corrected results meet the requirements," Dr. Wang added.
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