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Motor overheating? Wayon PPTC has the solution for you

Besides home and working place, car has become the third living space for human beings. The time people spend in their cars has gradually increased with the expansion of the city. Especially in the era of new energy vehicles, autonomous driving and in-vehicle interconnection have equipped the car with “faces, limbs and brains”, turning the car from a transportation into a life scenario. As smart driving technology and supporting amenities become more and more sophisticated, experience a home-like comfort in the car is not impossible anymore. 



In order to improve the comfortability, the car is equipped with extensive electric driven devices, such as window lifting, electronic door lock, seat adjustment, tailgate lifting, lumbar support, leg rest, headrest, mirror adjustment, sunroof, etc. The number and types of comfort equipment are increasing with the growth of passenger’s experience needs. At the same time, the configurations are gradually popularized from mid- to high-end models to all models. These car body equipment is driven directly by the small and medium-sized DC motors. The number of drive motors contained in a car, from a dozen to over a hundred (more than 2 billion / year globally) is growing year by year. 



Safety is a red line that cannot be crossed. It is the highest principle of all product development. As one of the core control technologies of modern automobile, the safety of motor drive itself is directly related to the safety of the car as well as the drivers and passengers. The product safety can only be fully validated by considering all system characteristics and conducting comprehensive failure mode analysis with respect to product usage scenarios.


As shown in figure 1, in the case of motor failure, jamming, blocking, etc., the motor coil generates a large amount of joule heat. If the motor current is not cut off in time, the temperature will be out of control, causing motor burning or even automobile combustion accidents.





Figure 1 Motor failure without protection scheme


The PPTC protection scheme is one of the mainstream protection solutions for small and medium-sized DC motors. When the motor blocks, PPTC generates joule heat. Once the amount of heat reaches a certain level, PPTC “activates” and trips into a high-resistance state, which cuts off the current flow to motor, thus achieving the purpose of protecting the motor. At this time, if the motor blocking fault remains, the PPTC also remains in a high-resistance state, so that there is no repeated "on-off" situation. In other words, the motor temperature is once suppressed to a low temperature state, as shown in figure 2 below.



Figure 2 Motor current and temperature rise of PPTC protection scheme

WAYON automotive standard PPTC products have the following features:
1. A variety of package profiles, which can be customized according to the internal space of the motor and the installation method, as shown in figure 3 below;
2. Temperature range of operating: -40-125℃;
3. Rated operating voltage: 16-60V, which can meet the usage environment of passenger and commercial vehicles;
4. Applicable motor stalling current up to 35A;
5. Resettable, small degree of characteristic decay, more than 10,000 lifetime;
6. High reliability, AEC-Q200 standard qualified;
7. The protection time can be adjusted according to the actual requirement of motor temperature rise.


Figure 3 WAYON automotive standard PPTC products



Figure 4 WAYON automotive standard PPTC application principle


Overheating may damage and burn out the car motor. By installing PPTC device close to the motor or coil, the heat from motor blocking will help the PPTC device to trip faster, thus protecting the motor from overheating.



Figure 5 Typical applications of WAYON products in electric motors


WAYON automotive standard PPTC products have been supporting international mainstream automotive motor manufacturers in Japan, Europe, the United States, etc. with a history of cooperation of more than 10 years. At the same time, WAYON has been supporting OEMs with its PPTC products, including BMW, Volkswagen, General Motors, Tesla, Peugeot Citroen, Renault, Honda, Toyota, Nissan, Hyundai, Geely, BYD and other major brands both domestic and overseas. The PPTCs are widely used in electric seat adjustment system, electric window adjustment system, electric door lock system and other body equipment, ensuring the comfortability and safety of the car.