Currently, the market is focused on large primary traction motors with evolutionary trends moving toward multiple drive motors and integrated drivetrains, often called eAxle, with a power inverter, and gearbox combined. In addition, many other motion control functions in the EV, such as power steering utilize servo control motors with fully integrated filters and power conversation technologies.
The overall design goals for new-generation custom-formed busbars:
To achieve the above goals, designers need to look for partners that can provide busbars with these key features:
As an experienced leader in busbars and other interconnects, Interplex has a long track record of pioneering innovation, which once again is being leveraged to provide highly configurable and robust custom busbar technologies for traction motor stators.
As shown below, these busbars are designed to accommodate hairpin windings typically used in advanced higher voltage motor stators and to provide a range of flexible multi-phase connections. They can handle a full range of high-voltage current requirements and use high-performance copper integrated with specially selected polymer materials for optimal dielectric isolation and improved thermal characteristics.
Interconnect methods comprise both pluggable interfaces and various bonding options, including:
Also, the Interplex solutions incorporate flexible multi-phase connectors because motor and inverter connectors do not always align perfectly and flexibility is helpful for final mounting and easier alignment for connection.
Other options include multi-phase stator bars to handle 3-phase or 6-phase application requirements.
One of the most important aspects is designing the busbars for required thermal performance and robust electrical performance at high temperatures. Because of the heat generated by the motors, traction drives are often cooled by oil. The combination of these factors means that proper materials selection and physical design are critical factors for success.
The Interplex Busbar Design Group has deep experience in materials science to determine the best options, along with applications-specific design expertise, FEA analysis, thermal management and design for manufacturing processes.
With oil-cooled drive motors typically operating in the 120-150°C range along with rapid heat rises of 30°C, the use of most plastics quickly becomes problematic. The Interplex team has found good results with high-temp, glass-filled plastic molding solutions that can deliver the best combination of thermal characteristics, electrical performance, chemical resistance and material strength needed for success. (More information on materials is available from Interplex.)
As EVs become a larger share of the overall vehicle market and automotive makers compete for various niches in this rapidly growing market, the need for a widening variety of drive motor configurations is a critical success factor. Designing robust motor stators and flexible interconnect methodologies lies squarely at the heart of this challenge.
Since there is no “one-size-fits-all” approach to motor stator design, automotive companies need access to vendors with a proven track record across all the disciplines described in this Tech Bulletin.
Interplex not only has the experience and expertise, we have also taken the proactive step of creating a broad-based foundation of configurable and adaptable technologies from which we can provide initial design support, rapid prototyping, testing and ramp-up to full production. These capabilities are also backed by the Interplex worldwide design, distributed manufacturing and logistics organization that provides unparalleled local support for automotive makers around the globe.
A critical factor for success with using new busbar technologies is to start early in the design process by working with a knowledgeable partner that can advise on a variety of approaches and can provide the best technology choice…
Customized flexible busbars for low voltage power applications. Excellent vibration and shock absorption characteristics with improved electrical conductivity and high tolerance for assembly mismatch/offset…