"44% of electric vehicle fires are linked to insulation problems in the battery system, suggesting the need for thorough validation at the design stage."
- EV Safety Report 2023, Global EV Safety Institute

As the electric vehicle industry grows rapidly, the voltage of the battery system is constantly increasing. As ultra-high voltage systems of 800V or higher emerge beyond the existing 400V system, battery insulation technology is emerging as a more important topic than ever, and in particular, the selection and design of insulation ICs are becoming key factors that determine the safety of electric vehicles.

Insulation design failures that entail fatal risks
Failure of insulation design can lead to catastrophic failures beyond simple performance degradation. In particular, thermal runaway in battery systems is the most worrisome risk factor. Once started, a thermal runaway can cause a chain reaction that can lead to an explosion of the entire battery pack, making it nearly impossible to extinguish with standard fire extinguishing equipment.



Key Elements of Battery Isolation IC Design

- A new paradigm in insulation voltage design
The isolation ICs of modern electric vehicle battery systems must basically support a stable operating voltage of 800 V or more. In addition, surge protection capability that can withstand momentary overvoltages is essential. It is essential to meet the strict certification standards of UL and IEC, and an even higher safety margin is required in actual operating environments.

- Evolution of real-time monitoring system
The latest insulation ICs must provide intelligent monitoring functions beyond simple voltage blocking. They must be able to measure insulation resistance values in real time and accurately detect even minute leakage currents. In particular, they must be able to safely shut down the system with a fast response speed of milliseconds when abnormal signs are detected.

- Ensuring reliability in extreme environments
Isolation ICs for electric vehicles must ensure stable performance even under extreme environmental conditions. It must be able to operate over a wide temperature range from -40°C to +125°C, as well as withstand high humidity and continuous vibration. In addition, a robust design that is immune to various electromagnetic interference (EMI) within the vehicle is essential.

Design vulnerabilities discovered in the field
- Safety degradation due to cost reduction
There are cases where some manufacturers are lowering the specifications of the isolation IC to reduce costs. This is a very dangerous approach. In fact, it is significant that many recent electric vehicle fire accidents are related to improper insulation design.

- Limits of test scope
Another problem is that insulation performance tests are conducted only under limited conditions. A comprehensive test that takes into account all the various stress situations that may occur in an actual road driving environment is needed.

Future Technology Outlook
- AI-based predictive management system
Technology is being developed to detect potential risks in advance by analyzing insulation status using AI algorithms. This is expected to enable preventive maintenance beyond conventional simple monitoring.

- The emergence of new insulating materials
Beyond the existing silicon-based insulators, insulating ICs using new materials such as gallium nitride (GaN) and silicon carbide (SiC) are being studied. These will enable stable operation at higher voltages and temperatures.

The safety of electric vehicle battery systems is largely dependent on the design quality of the isolation IC. Compromising the quality of the isolation design to reduce costs is a dangerous choice that threatens the safety of passengers. The importance of insulation technology is expected to continue to grow with the strengthening of safety regulations in the future. Electric vehicle manufacturers should keep an eye on this trend and maintain a design philosophy that prioritizes safety.