The Tesla Model 3/Y uses the TPAK Silicon Carbide MOSFET module, which has an excellent design that makes it a good general purpose high-voltage high-power package. This article will start from this silicon carbide module to talk about the Tesla core power chip selection strategy observed by the author.
TPAK
TPAK does not include the plastic part of the pin size of 20mm x 28mm x 4mm, which can not only be loaded with a bare silicon carbide MOSFET chip, but also can choose IGBT or gallium nitride HEMT as its core chip. This means that TPAK can not only be used as a high-performance silicon carbide drive module, but also a cost-effective IGBT power module, and even after the maturity of the high-power gallium nitride technology of the car specification, the naked gallium nitride chip is seamlessly connected to become a high-frequency power switching device.
TPAK appearance. This version is produced by STMicroelectronics (Source: System Plus Consulting)
At the same time, combined with multi-tube parallel technology that has been immersed for many years, Tesla can select different numbers of TPAK parallels according to different power levels in its electric vehicle drive system, and select silicon carbide MOSFETs or IGBTs as the core chips of TPAK according to different efficiency and cost requirements. At the same time, because they are all the same package, Tesla only needs to meet a variety of electric vehicle drive needs with only minor changes in external circuits, mechanical structures and thermal designs, which greatly increases design flexibility.
For example, under ideal circumstances, a dual-motor version of a Tesla electric vehicle could use multiple silicon carbide TPAK to drive the main motor in parallel to meet performance and efficiency requirements in most operating conditions. The other motor can be selected with a smaller number of parallel silicon carbide versions or IGBT versions of TPA to achieve four-wheel drive or acceleration requirements under certain cost control. Or in the future, the use of gallium nitride + silicon carbide or gallium nitride + IGBT scheme.
4 Model 3 inverters in parallel with TPAK SiC (Source: Munro & Associates)
Not only that, each die in TPAK can also be purchased from different chip suppliers to establish a two-supply or even multi-supply system. In addition to the official STmicroelectronics, Tesla also cooperates deeply with almost all well-known power semiconductor head suppliers in the industry - Tesla provides technical specifications and various working conditions in the application scenario, and chip manufacturers come up with the best power semiconductor technology to customize power switch chips for TPAK. The advantage of this is that you can choose the best among many suppliers and find the chip with the best performance or the highest cost performance for Tesla models.
At the same time, Tesla can quickly increase the capacity of TPAK modules through multiple suppliers when its model sales increase, without being limited to a single supplier, which is particularly important in the case of rapid growth in Sales of Model 3/Y models compared to the previous generation Model S/X. In the future, when Tesla launches the Model 2 with cheaper sales expectations and the Cyberruck with a predetermined volume of more than one million units, being able to obtain a massive supply of TPAK modules from multiple semiconductor suppliers in a short period of time will become an important part of Tesla's supply chain management.
It is true that if the oem adopts a pin-compatible module such as HybiPACK 1 or Trac Direct (DC), it can also get a similar multi-supplier system to guarantee the supply, but this module is a module first, and then there is an inverter system, so in some specifications different manufacturers can not achieve 100% compatibility. In addition, the module is full-bridge design (including 3 half-bridges), the package cost is fixed, so when improved to a low-current version of the module, the total cost of the module does not decrease synchronously with the current specification, so the design flexibility is not as good as TPAK. Finally, as a publicly designed module, the inverter designer cannot distinguish it from competitors using the same module in terms of module performance.
Infineon and ON Semiconductor's full-bridge IGBT modules, both pin compatible but with subtle differences (Source: Infineon Technologies, ON Semiconductor)
In summary, in the selection of the inverter core power device, Tesla is not only involved in the definition, design and testing of the internal chip in addition to specifying the form factor and some important package design requirements (such as the use of silver sintering technology). The resulting TPAK module not only meets the performance and system design requirements, but also realizes the cross -- (chip) vendor,cross-(IGBT/SiC MOSFET/GaN HEMT) platform.
T2PAK
Coincidentally, in addition to TPAK, Tesla also adopted the same selection strategy in pcS, another core component of the powertrain.
The Model 3/Y's Power Conversion System (PCS) consists of two parts, the on-board charger OPC and the high-voltage-12V DC/DC, for charging the main battery pack from the grid and the energy exchange between the main battery pack and the 12V battery. There are more than 40 pieces of T2PAK (2nd Tesla Package) in the PCS for the primary and secondary side of PFC and DC/DC in OBC, and the high-voltage side of high-voltage -12V DC/DC.
Tesla Model 3/Y power conversion system with Model S/X third-generation car charger. It can be seen that the package of the core power device has been replaced from TO-247 to T2PAK (Source: Phil Sadow/Ingineerix, Anner J. Bonilla)
As a high-voltage single-tube surface-mount package, the T2PAK replaces the TO-247 package used in previous generations of Model S/X OBCs, including to-247-3 for superjunction MOSFETs, three-pin packages for SiC MOSFETs, and TO-247-2, two-pin packages for silicon or silicon carbide diodes. Therefore, T2PAK is simpler to install on the MAIN PCS board and is more productive. All T2PAKs are applied to the water-cooled heat sink by thermal paste, which is greatly simplified compared to the previous heat dissipation design.
According to the dismantling video that can be found so far, the T2PAK has at least a silicon carbide diode, as well as several versions of the superjunction MOSFET or silicon carbide MOSFET. Similarly, T2PAK simplifies the supply chain by enabling cross-platform and cross-vendor selection of core power devices in PCS in a single package.
T2PAK diode labeled SiD600 in PCS (Source: Phil Sadow/Ingineerix)
Of course, TPAK and T2PAK are not perfect, and there is still a lot of room for improvement in the packaging of both devices. For example, TPAK can use technologies like Danfoss DBB and Heraeus Electronics DTS to achieve double-sided sintering inside the module for better heat dissipation performance and reliability.
Some controversy
Some readers had a lively discussion about tesla and BYD who are stronger in powertrain hardware technology. I have worked with both companies for a long time, and it can be said that they are one of the best companies in the industry in the field of electric vehicles. However, considering the different environments and national conditions in which BYD and Tesla are located, the entrepreneurial genes of the two are also very different, and if you compare the advantages and disadvantages of the two, if you compare the lions and tigers in different ecosystems, it is difficult to judge who is the king of the hundred beasts.
Tesla is in the core of Silicon Valley Palo Alto, since the launch of the Model S has become one of the most important customers of many semiconductor companies, can be unrestricted procurement of any power semiconductor head enterprise cutting-edge products, so Tesla only need to focus on the main business, focus on the vehicle level and part of the core subsystem research and development.
When BYD began to do electric vehicles, domestic vehicle specification power semiconductors had not yet started, and IND was not the most important customer in the eyes of foreign suppliers, so BYD had to develop its own IGBTs and silicon carbide MOSFETs as supplements and alternatives to foreign products. This allows BYD to gain a certain bargaining power in the procurement of power semiconductors, and has a backup solution in the event of external supply shortages, which has obvious advantages in the context of today's automotive electronics core shortage. However, when BYD needs huge investment in many tracks such as automobiles, semiconductors, lithium batteries, etc., in order to compete with opponents in terms of technology and production capacity (such as the Ningde era in the field of lithium batteries), there will be a situation of shortfall in resources. It is expected that BYD Semiconductor's meeting in the next few days until the subsequent listing will inject a shot of strength into BYD's silicon carbide and IGBT research and development and capacity expansion.
All in all, there is no one-size-fits-all approach to the selection strategy of core power devices, and companies need to decide to use completely self-produced, completely outsourced, or customized solutions like Tesla according to the company's specific situation and market dynamics.