Energy-saving and environmentally friendly automotive circuit protection solution

In recent years, the environment has been deteriorating, the greenhouse effect has been strengthening, and the awareness of low-carbon life has sounded the alarm in people's hearts. Electric vehicles and hybrid vehicles are favored by the public for their environmental protection and energy saving advantages. Auto engineers are forced by the guidance of government policies and the pressure of industry competition to increase the funding. From the automotive industry's important electronic components, automotive wiring harnesses, automotive connectors, power supplies, etc., automotive engineers continue to develop energy-saving and environmentally-friendly vehicles that conform to the development of the times.

More environmentally friendly, lighter design

For today's automotive engineers, improving fuel economy and reducing greenhouse gas (GHG) emissions have become important design guidelines. Obviously, electric and hybrid vehicles are the solution to these challenges, but the technology to reduce the weight of the car can also provide some obvious benefits because reducing vehicle weight and rolling resistance can reduce energy demand and effectively reduce carbon dioxide emissions. .

In addition to improving component integration and the use of advanced materials to help automakers reduce vehicle weight, harness weight is also an area of particular interest and has attracted design engineers to re-examine their designs to prevent automotive power. The function is damaged due to a large current fault condition.

One of the challenges faced by design engineers is to retain and/or add circuit protection devices that help protect automotive electronic systems from possible overload conditions while reducing overall cost and weight. Since a car can typically contain hundreds of circuits and more than one kilometer of wire, the complexity of the wiring system can make traditional circuit design techniques difficult to use and can lead to unnecessary over-design.

Many manufacturers have found that combining a distributed architecture with a resettable polymer positive temperature coefficient (PPTC) overcurrent protection device can significantly reduce vehicle weight. The centralized solution requires each module to be protected by a separate fuse in the junction box. In this "star" architecture, each function also requires separate wires, which adds weight and cost. Conversely, in a distributed architecture where multiple junction boxes are powered by the power bus, each of the wires coming out of the junction box is protected by a resettable circuit protection device.

In the past, mechanical strength specified the finest wire used in automobiles to be 0.35 square millimeters (22 AWG), which can carry currents ranging from 8A to 10A. This limitation offsets to some extent the benefits of using PPTC devices in low current signal circuits (eg, below 8A). However, current wire material technology can support smaller diameter conductors with a given current carrying capacity, including wires with a diameter of 0.13 square millimeters (26 AWB) and a maximum current of 5A. This advanced technology can alleviate more weight when using distributed architecture and PPTC overcurrent protection.