Five Key High-Voltage Safety Design Principles in Electric Vehicles
In battery electric vehicles (BEVs), the propulsion system is powered by high-voltage electric motors. These systems typically operate at very high currents—ranging from tens to even hundreds of amperes—and in the event of a short circuit, the current can spike dramatically. Such high voltages and currents pose significant safety risks to both passengers and vehicle components, including electrical systems and control units.
Therefore, the high-voltage electrical system in an EV must not only meet performance and power delivery requirements but also ensure operational safety, personal safety, and safe maintenance. Effective high-voltage safety management involves a combination of technical design, operational protocols, protection mechanisms, and user safety education.
Below are five fundamental safety design principles widely adopted in EVs to ensure safe handling and operation of high-voltage systems:
1. Leakage Current Protection
Electric vehicles are equipped with leakage current protection devices. If either the positive or negative high-voltage bus comes into contact with the vehicle chassis, the protection device will trigger an alert—or in many cases—automatically shut down the high-voltage supply. This prevents scenarios where the motor casing becomes electrically charged, which could lead to an electric shock if someone touches the opposite pole. Leakage protection also safeguards systems such as the air conditioning unit and DC/DC converters from high-voltage leakage.
2. High-Voltage Interlock (HVIL)
All high-voltage connectors are designed to prevent disconnection while the system is energized. However, to guard against human error or unauthorized tampering, high-voltage interlock (HVIL) switches are integrated into connectors. If a connector is unplugged, the interlock circuit is immediately interrupted. The system controller detects this and rapidly disconnects the main relay, cutting off high-voltage power in milliseconds—thereby preventing potential electric shock. HVIL is a critical fail-safe in high-voltage circuit design.
3. Collision Power Cutoff
In the event of a collision, onboard crash sensors immediately send a signal to trigger the HVIL system. This automatically disconnects the vehicle’s high-voltage power supply to protect occupants from electric hazards. Some modern systems integrate this function directly into the high-voltage connector modules, combining sensing and cutoff in a compact unit.
4. Insulation Resistance Monitoring
Higher system voltages require stricter standards for insulation to prevent dangerous leakages. Insulation resistance is a critical safety parameter, with regulatory standards clearly defining minimum thresholds to mitigate risks of electric shock or component failure.
Two common methods are used to monitor insulation resistance:
- Auxiliary Power Method:
A 110V DC auxiliary battery is connected across the high-voltage circuit (positive to negative, and negative to vehicle ground). Under normal conditions, no current flows. If insulation is compromised—due to aging, moisture, etc.—a leakage current forms, triggering an alert and shutting down the system. While effective, this method increases system complexity and cannot easily identify whether the issue lies in the positive or negative lead, limiting its application in EVs. - Current Sensor Method:
Hall-effect current sensors measure differential current flow by passing both positive and negative cables through the same sensor. When no leakage is present, the outgoing and returning currents cancel out, and the sensor reads zero. If leakage occurs, the imbalance is detected, and the direction of current flow helps identify whether the fault is on the positive or negative side. This method requires the system to be powered during testing but is more commonly used in modern EVs due to its efficiency and precision.
5. Access Panel Monitoring
Certain critical high-voltage components in EVs are equipped with cover monitoring mechanisms. If a cover is opened while the high-voltage system is still active, a signal is sent to the main controller. The controller immediately cuts off the main relay and activates a discharge mechanism that rapidly reduces internal voltage to safe levels. This feature ensures safety during servicing or accidental opening of enclosures.
Conclusion
High-voltage safety is foundational to electric vehicle design. From real-time system monitoring to automatic disconnection features, these protective measures are vital for ensuring the safety of passengers, maintenance personnel, and the vehicle itself. As EV technology continues to evolve, robust safety protocols will remain essential in supporting the growth of safe and reliable electric mobility.
About Brogen
At Brogen, we provide advanced EV solutions for global commercial vehicle manufacturers, enabling them to streamline research and development while capitalizing on cutting-edge technology. Our offerings ensure superior efficiency, extended range, and seamless system integration with proven reliability—empowering our partners to lead in the rapidly evolving green mobility landscape.
Currently, our EV solutions for battery electric buses and trucks have been adopted by vehicle manufacturers in countries and regions such as Australia, Türkiye, Brazil, the Philippines, Indonesia, the Middle East, and more.
- Looking for an EV solution for your project? Reach out to us at contact@brogenevsolution.com
Contact Us
Get in touch with us by sending us an email, using the Whatsapp number below, or filling in the form below. We usually reply within 2 business days.
Email: contact@brogenevsolution.com
Respond within 1 business day
Whatsapp: +8619352173376
Business hours: 9 am to 6 pm, GMT+8, Mon. to Fri.
LinkedIn channel
Follow us for regular updates >
YouTube channel
Ev systems introduction & industry insights >
