EV Industry

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. 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Vehicle Control Unit (VCU) Explained: A Deep Dive into Software Architecture The Vehicle Control Unit (VCU) is often referred to as the “brain” of the vehicle. It plays a pivotal role in managing and coordinating various systems to ensure efficient, safe, and intelligent vehicle operation. At the core of its operation is a well-structured software architecture, typically divided into three key parts: Signal Input, Function Control, and Signal Output. 1. Signal Input – The “Senses” of the Vehicle Control Unit (VCU) The signal input section enables the VCU to perceive the vehicle’s real-time status, much like how human senses gather information from the environment. The VCU collects data from three primary channels: hardwired inputs, the CAN bus (Controller Area Network), and low-level diagnostic signals. Hardwired Inputs: These are like the vehicle’s nerve endings, directly connected to key components. Through these inputs, the VCU gathers critical information such as accelerator position, brake pedal status, ignition key state, and more. This data reflects the driver’s direct commands and helps the VCU respond accordingly. CAN Bus Inputs: Acting as the vehicle’s internal communication highway, the CAN bus connects essential systems such as the battery management system (BMS), motor control unit (MCU), and transmission control unit (TCU). The VCU monitors these systems in real time, allowing precise and coordinated vehicle control. Low-Level Diagnostics: This includes internal controller states, E-flash storage signals, and I/O diagnostics. Think of it as the vehicle’s health report, providing deeper insights to support system reliability and performance monitoring. 2. Function Control – The “Brain” of the Vehicle Control Unit (VCU) This is the core processing layer of the VCU. Based on the inputs received, the VCU makes intelligent decisions to manage vehicle behavior. While features may vary between manufacturers, most VCUs include the following key control functions: Input Signal Processing: Acts as a centralized filter and organizer. It processes signals such as speed, acceleration, braking, gear logic, and vehicle weight. By unifying data at this layer, the VCU improves efficiency and reduces redundant signal processing across different functional modules. Power Management (Power On/Off Control): The VCU coordinates the high-voltage system to manage key processes, including pre-charging, enabling power output, and entering sleep modes. It ensures components are powered on or off in a safe and orderly manner. Additional features like smart battery charging and battery preheating can also be integrated here. Torque Control: One of the VCU’s main roles is controlling the vehicle’s torque output based on driver inputs such as acceleration or braking. This function ensures smooth torque delivery across various drive conditions like cruising, crawling, or rapid acceleration. Single Power Source Vehicles: For vehicles with one drive motor or a conventional ICE powertrain, the VCU arbitrates between different torque demands (e.g., acceleration, crawl, cruise), filters out torque interference (e.g., from gear shifts or stability control), and adjusts torque output for smooth driving. Multi Power Source Vehicles: In EVs with dual motors or hybrid configurations, after determining total torque demand, the VCU distributes torque appropriately between power sources and filters each source’s output to maintain stability and performance. Energy Management: The VCU optimizes energy usage based on the vehicle’s configuration. Battery Electric Vehicles (BEVs): The VCU controls high-voltage components (DCDC, air pumps, HVAC systems) and calculates available power to adjust motor torque output, improving energy efficiency. Fuel Cell or Range-Extended Vehicles: Whether powered by hydrogen or fuel, these systems rely on the VCU to balance energy supply and demand, activate generation systems as needed, and ensure optimal energy use. Fine-tuned control is required to handle differences in startup behavior, power response, noise/vibration (NVH), and energy consumption. Auxiliary Functions: Many VCUs are equipped with additional smart features, such as: Dashboard Display Control: Provides real-time information such as range, average energy consumption, power output, and gear status to the driver. Anti-Theft & Lock Control: Implements features like random key generation, security level control, and key verification for enhanced vehicle protection. PTO (Power Take-Off) Control: Supports operational requirements in special-use vehicles by managing PTO status, speed control, and idle conditions. Auxiliary Systems Management: Oversees the operation of water pumps, cooling fans, vacuum pumps, EPS motors, and air compressors. 3. Signal Output – The “Executors” of VCU Commands This layer handles the transmission of control signals generated by the VCU to the vehicle’s actuators. The output methods include hardwired signals, CAN communication, and data storage: Hardwired Output: Used to enable or wake up components like the BMS, MCU, and TCU. It also provides direct control over specific functions such as pump and fan speed. CAN Output: Enables efficient communication with various high-voltage systems, controlling torque commands, motor speeds, generator activation, relay switching, and more. E-Flash Storage: Stores vital data such as mileage, learned values, and average energy consumption to support diagnostics, analytics, and long-term performance optimization. Conclusion By understanding the structure and function of a Vehicle Control Unit, we can better appreciate the role it plays in enabling intelligent, efficient, and safe vehicle operation. Whether it’s managing torque output, coordinating energy use, or communicating with dozens of subsystems, the VCU lies at the heart of modern vehicle control strategies. 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