EV Industry

DC-DC Converter in EVs: Role, Architecture, and Opearting Principles 1. The Role of a DC-DC Converter In simple terms, a DC-DC converter in an electric vehicle (EV) is a step-down voltage converter. Its primary function is to convert the high-voltage DC power from the traction battery into the low-voltage DC power required by the vehicle’s auxiliary electrical system. Conventional internal combustion engine (ICE) vehicles: Powered by an alternator and a 12V lead-acid battery, which supply electricity to components such as headlights, infotainment systems, the ECU, power windows, door locks, and wipers. Electric vehicles: Since there is no engine, there is no alternator. Instead, EVs rely on a high-voltage traction battery (typically 200V-800V) for propulsion. However, most onboard systems – such as the instrument cluster, lighting, infotainment, controllers, and window motors – still operate on a traditional 12V low-voltage system. Without a conversion path, energy cannot flow between the high-voltage and low-voltage domains. The DC-DC converter bridges this gap. It replaces the alternator in ICE vehicles and acts as the core low-voltage power supply in EVs. 2. Circuit Composition of a DC-DC Converter Most EVs use isolated LLC resonant DC-DC converters, either unidirectional or bidirectional. While sophisticated in design, their operating principle is similar to that of a common switch-mode power supply. A typical DC-DC converter consists of the following components: 2.1 Main Power Circuit Input EMI filer: Smooths the high-voltage DC from the traction battery, reducing voltage ripple and electromagnetic interference. Power switching stage: Typically a half-bridge or full-bridge structure. Controlled by high-frequency switches (MOSFETs/IGBTs), the DC input is inverted into a high-frequency AC square-wave signal. This is the core of energy conversion. High-frequency transformer: Electrical isolation: Provides galvanic isolation between high-voltage and low-voltage sides for safety and noise immunity. Voltage transformation: Achieves step-down conversion according to the winding ratio. Output rectifier: Converts the transformer’s secondary high-frequency AC into DC. Typically implemented with diodes or synchronous rectification MOSFETs. Output filter: A combination of inductors L and capacitors C smooths the rectified DC to provide a stable 12V output. 2.2 Control and Drive Circuit Main control unit: The “brain” of the DC-DC converter. It continuously monitors voltage and current, compares them with reference values, and generates PWM signals to adjust the duty cycle of the switching devices for precise voltage regulation. Driver circuit: Amplifies the PWM signals from the control unit to ensure the power switches operate rapidly and efficiently. Sampling and protection circuit: Continuously monitors input voltage, output voltage, output current, and temperature. In case of over-voltage, under-voltage, over-current, over-temperature, or short-circuit conditions, the controller immediately shuts down PWM input to protect both the converter and the low-voltage system. 3. Operating Principle of a DC-DC Converter The working process can be summarized in four stages: DC → High-Frequency AC → Transformation → DC. Inversion (DC-AC): The control unit generates four PWM signals to alternately drive the switches in the full-bridge circuit (Q1-Q4). This converts the high-voltage DC (e.g., 400V) into a high-frequency AC square wave, typically in the kHz range. Transformation & Isolation: The AC signal passes through the LLC resonant tank, enabling zero-voltage switching (ZVS) of MOSFETs, which minimizes switching losses and improves efficiency. The high-frequency transformer then steps down the voltage and provides galvanic isolation. Rectification (AC-DC): The transformer’s secondary AC output is rectified by the output stage, often using synchronous rectification with MOSFETs to reduce conduction losses compared to diodes. Filtering & Output: The rectified pulsating DC passes through an LC filter to produce a stable 12V DC supply for onboard low-voltage devices. Closed-Loop Feedback Control: The control chip continuously monitors the output voltage via sampling resistors. If the load increases (e.g., headlights and AC operating simultaneously) and the voltage drops, the controller increases the PWM duty cycle to deliver more energy to the low-voltage side, restoring the output to 12V. If the load decreases, the duty cycle is reduced. This negative feedback loop ensures that the DC-DC converter maintains an extremely stable 12V supply regardless of load variations. Our DC-DC Converter Solutions At Brogen, we provide a full range of DC-DC converter solutions for electric vehicles, covering power outputs from 0.6 kW to 6 kW, with options for natural, air, or water cooling. Our portfolio also includes OBC & DC-DC combo units, as well as 3-in-1 CDU combo units that integrate the OBC, DC-DC, and PDU into a single compact system. Learn more here: https://brogenevsolution.com/obc-dcdc-pdu/ 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 > ContactFill in the form and we will get in touch with you within 2 business days.Please enable JavaScript in your browser to complete this form.Please enable JavaScript in your browser to complete this form. Name * FirstLast Work Email *Company Name *Your Project Type *– Please select –Car, SUV, MPVBus, coach, trainLCV (pickup truck, light-duty truck, etc.)HCV (heavy-duty truck, tractor, trailer, concrete mixer, etc.)Construction machinery (excavator, forklift, crane, bulldozer, loader, etc.)Vessel, boat, ship, yacht, etc.Others (please write it in the note)Your Interested Solutions *– Please select –Motore-AxleBatteryChassisAuxiliary inverterOBC / DCDC / PDUAir brake compressorEPS / EHPS / SbW / eRCBBTMSOthers (please write it in the note)Do you have other contact info? (Whatsapp, Wechat, Skype, etc.)Please introduce your project and your request here. * Checkbox * I consent to receive updates on products and events from Brogen, and give consent based on Brogen’s Privacy Policy. Submit

High Voltage Wire Harnesses in Electric Vehicles: Key Design Principles High voltage wire harnesses play a critical role in electric vehicles, transmitting high voltage and large currents between essential components like the battery pack, high-voltage PDU, inverter, and traction motor. These harnesses ensure efficient energy transfer, enabling EV systems to operate in perfect synchronization. Proper installation and secure mounting of high voltage wire harnesses is essential for safety, reliability, and performance..  1. Routing Principles for High Voltage Wire Harnesses Before discussing installation and fixation, it’s crucial to understand routing principles. 1.1 Proximity Principle The routing should follow the shortest feasible path to minimize voltage drop and weight, which supports efficiency and cost reduction. 1.2 Ease of Assembly The overall design and fixation method of the EV wiring harness should prioritize ease of assembly to ensure simple and efficient installation. Connector Mounting and Fixation: Allow adequate length and installation space for connectors to facilitate smooth operations. Harness and Component Fixation: Ensure sufficient clearance for fastening tools, maintaining at least a 50 mm gap from the center of the nut for safe operation. Harness Clip Fixation: Position harness clips strategically to minimize quantity while ensuring secure attachment. 1.3 Maintainability The principle of good maintainability in automotive wiring harness design means ensuring ease of maintenance and repair throughout the vehicle’s lifecycle. The layout should allow faults to be diagnosed and repaired in the shortest possible time while minimizing the impact on other components. Connector Placement and Fixation: Connectors should be positioned within easy reach. For connectors that require single-hand operation, the opposite end should be securely fixed. Avoiding Misconnection and Providing Extra Length: Connectors on the same component should be arranged to prevent incorrect mating. The end of the wiring harness should have a reserved length. For example, high-voltage wires near the connector tail must not be bent or stressed, must not be twisted, and should be secured within 120 mm. Fuse Box Harness Allowance: The wiring harness for the fuse box should have sufficient slack to provide adequate operating space during maintenance. 1.4 Safety and Reliability Ensuring the safe and stable operation of the electrical system – and by extension, the proper functioning of all vehicle electrical equipment – is the ultimate goal of wiring harness design. Harness Fixation Location: Whenever possible, secure wiring along edges, channels, or areas that are less likely to be touched to prevent external forces from damaging the harness. Avoid Sharp Bends: When bends are unavoidable, allow adequate space and apply special fixation at the bend points. Ensure no kinks or excessive stress occur. Prevent Cable Damage: Harnesses passing through holes must be protected with sleeves, grommets, or protective tape to avoid abrasion. In the event of a collision, the harness should not be crushed, as this could lead to rupture and short circuits. High-Voltage Wire Harnesses Wrapping Materials Maintain Design Allowance: For main branches, ensure a sufficient bending radius to avoid tight routing that complicates assembly. Do not pull harnesses too tightly during installation, as vibrations during driving could shift fixation points. Avoid High-Vibration Zones: High-voltage harnesses should be routed away from major vibration sources such as air compressors or water pumps. If unavoidable, allow adequate slack based on vibration amplitude and the maximum motion envelope of moving parts to prevent tension on the harness. Avoid High-Temperature Zones: Keep harnesses away from high-temperature components such as compressors, brake lines, steering pumps, or oil pipes to prevent insulation melting or accelerated aging, which could lead to exposed conductors and short circuits. Maintain Bend Radius for High-Voltage Cables: Over-bending high voltage wire harnesses increases resistance, causing higher voltage drop and accelerating insulation aging or cracking. The minimum bend radius should be at least 4x the cable’s outer diameter. High-voltage cables exiting connectors must remain straight, without bending, twisting, or stress. Correct Connector Layout Example (Left) | Incorrect Connector Layout Example (Right) Sealing and Waterproofing: To enhance mechanical protection and ensure dust and water resistance, use seals or gaskets at connector interfaces and cable entry points. This prevents moisture and debris ingress, ensuring insulation integrity and avoiding short circuits, arcing, or leakage. 1.5 Aesthetic and Organized Routing Hidden or Aligned: Harness routing should prioritize a neat and aesthetic layout, either by concealing the harness or arranging it in a horizontal and vertical orientation. The routing should follow the direction of the adjacent components and, in the projected view, maintain a straight, grid-like arrangement wherever possible. Diagonal paths and crossing layouts should be avoided. The harness should align with surrounding harnesses, water pipes, air pipes, and oil pipes to maintain visual uniformity and an overall clean appearance. 2. Installation and Fixation Design for High Voltage Wire Harnesses 2.1 Planning of Harness Fixation Points The distribution of fixation points is the foundation for securing high-voltage harnesses and directly impacts their stability. Generally, the placement of these points should be determined based on factors such as harness length, routing, and bending positions. For longer harnesses, additional fixation points are necessary to prevent displacement caused by vibrations during vehicle operation. At bends, fixation points should be placed at both the start and end of the curve to avoid excessive stress on the harness in these areas.  Securing High-Voltage Wiring Harness at Bend Points The spacing requirements for fixation points vary according to the cross-sectional area of the harness. Typically: For smaller harnesses (≤16 mm²), the spacing can be slightly larger but should not exceed 300 mm. For larger harnesses (>16 mm²), due to greater weight and mechanical stress, the spacing should be kept within 200 mm. Additionally: The distance from the high-voltage connector outlet to the first fixation point should be ≤100 mm. The clearance between the high-voltage harness and heat sources should be >200 mm. Through proper planning of fixation points, issues such as shaking or displacement during vehicle operation can be effectively avoided, ensuring stable and reliable power transmission. 2.2 Selection of Fixation Methods In the installation of high-voltage harnesses for electric vehicles, common fixation methods include cable ties, clips,

The Role of the VCU in Electric Vehicles In traditional internal combustion engine (ICE) vehicles, control systems are relatively segmented, with components like the ECU, TCU, ABS, BCM, PEPS, and IPC. In electric vehicles (EVs), the engine and transmission are replaced by the electric motor and battery system. This shift introduces new key systems like the BMS and MCU. Beyond this fundamental shift, EVs also integrate a broad array of high- and low-voltage systems, such as DC/DC converters, onboard chargers (OBC), PTC heaters, and electronic braking systems (EBS), alongside intelligent controllers including the In-Vehicle Infotainment (IVI) system, Thermal Management System (TMS), Telematics Control Unit (T-Box), and Integrated Power Brake (IPB), etc. Why is a VCU Essential for Electric Vehicles? As vehicles evolve, so does the complexity of electronic controls. The number of controllers on board has significantly increased, especially in hybrid electric vehicles, where coordination between the traditional engine system and the electric drivetrain is critical. For example, when the ECU and MCU issue conflicting commands, which system should take priority? This type of decision-making requires a central coordinator – the VCU – to act as the vehicle’s brain. Beyond conflict resolution, EVs also have higher demands for drivability, energy efficiency, and real-time coordination across multiple subsystems. A VCU is necessary to optimize energy use, balance power delivery, improve safety, and ensure consistent performance across various scenarios. VCU Functional Overview The functions of the VCU vary depending on the overall vehicle system architecture. They can be categorized into several functional domains, including vehicle system control, powertrain management, electric power systems, thermal management, diagnostics, communication, and safety monitoring. Key functions include torque control and management, overall energy management, charging and thermal management, fault diagnosis and handling, as well as vehicle status monitoring. 1. Torque Management Torque management governs a vehicle’s acceleration and braking performance – both of which are determined by torque output from the electric motor or engine. The VCU interprets signals from the accelerator and brake pedals (e.g., depth and speed of press), determines the required torque, and coordinates the engine, generator, and coordinates the engine, generator, front and rear drive motors to respond accordingly based on the vehicle’s current operating mode. Case Example: Torque Distribution in AWD EVs All-wheel-drive EVs (as opposed to two-wheel-drive models) feature both front and rear motors. The VCU is responsible for intelligently distributing torque between the two, depending on the efficiency (economy), performance, and stability.   The goal of economic torque distribution is to achieve optimal overall efficiency under the current torque demand. This involves intelligently coordinating dual-, triple, or quad-motor systems to ensure the most efficient power distribution, reducing energy consumption and extending battery range. This strategy is typically applied during steady-speed driving scenarios, such as cruising on highways. In the performance-oriented torque distribution, the load distribution function calculates the optimal torque ratio between the front and rear axles by recognizing current road gradients and the vehicle’s acceleration or deceleration status. By building a dynamic load model, the system automatically adjusts torque distribution during load transfers to make full use of the maximum available tire grip. This reduces wheel slip and enhances the vehicle’s acceleration performance. Performance-oriented torque distribution must especially account for scenarios where a wheel becomes stuck and starts to slip, such as in mud or loose terrain. The basic principle is to actively adjust the torque distribution between the front and rear axles, transferring power to the axle that still has traction when one is slipping. This helps reduce power loss. When alternating slip between the front and rear axles is detected, the system dynamically adjusts torque distribution to maximize available grip, enhancing the vehicle’s ability to escape low-speed traction challenges. Stability-oriented torque distribution focuses on maintaining vehicle stability during steering maneuvers. While systems like ESP are designed to ensure body stability, frequent ESP interventions can lead to an uncomfortable driving experience. By monitoring steering behavior and controlling steering torque, the VCU can proactively adjust front and rear axle torque distribution in real time – before ESP activation – to correct vehicle dynamics. This helps suppress understeer (US) and oversteer (OS), reducing the need for ESP intervention during acceleration and cornering. As a result, it minimizes braking jolts and yaw disturbances, enhancing overall driving comfort and control. When calculating the drive torque, it’s also necessary to consider the vehicle’s driving mode. Under different modes, the accelerator pedal position and vehicle speed are used to first determine the base drive torque. This base drive torque typically corresponds to the ECO mode. If the vehicle is in Normal mode, an additional compensation torque is applied. In Sport mode, a larger compensation value is added to enhance performance. 2. Mode & Energy Management 2.1 Operating Modes In addition to driving modes, vehicles – especially hybrid models – also operate under different operation modes. These include pure electric mode, series (range extender) mode, and parallel mode. While both driving modes and operation modes aim to optimize energy efficiency and power distribution, they differ in how they are set: Driving modes (such as ECO, Normal, and Sport) are manually selected by the driver. Operation modes are automatically determined by the vehicle. In pure electric mode, the vehicle is powered solely by the electric motor using energy from the battery. The engine remains off. In series mode (range extender mode), the engine, generator, and battery are connected in series. When the battery’s state of charge is low, the engine activates the generator to produce electricity, which recharges the battery – effectively extending the vehicle’s range. In parallel mode (direct drive mode), both the engine and the battery provide propulsion simultaneously. Typically, the engine drives one axle while the electric motor powers the other. Since the engine directly contributes to wheel drive in this mode, it is also referred to as direct drive mode.  So how does the vehicle decide whether to use fuel or electricity? The decision of whether to use fuel or electricity in different driving scenarios is made based on energy efficiency.

In-Depth Overview of Battery Thermal Management Systems for Electric Semi Trucks As electric semi trucks gain traction in global logistics, maintaining battery performance and safety under varied environmental conditions is critical. This is where the Battery Thermal Management System (BTMS) comes into play. 1. Introduction of BTMS for Electric Semi Trucks The Battery Thermal Management System (BTMS) in electric semi trucks is a closed-loop liquid cooling system composed of coolant circuits and thermal conductive media. By leveraging sensors and a control unit, the system actively regulates coolant temperature to keep the traction battery pack operating within an optimal thermal range. This ensures peak battery performance, extends service life, and enhances overall vehicle safety. 1.1 Key Functions of the BTMS Cooling: When battery cell temperatures rise excessively, the system activates cooling to prevent thermal runaway and potential safety incidents. Preheating: In low-temperature environments, the system preheats the battery cells to ensure safe and efficient charging/discharging operations. Temperature Equalization: It reduces internal temperature differences among cells, minimizing localized overheating and maintaining uniform battery performance. 1.2 Structure and Operating Principle The BTMS consists of the following major components: Liquid Cooling Unit: Provides pressurized, temperature-regulated coolant to the system. Expansion Tank: Manages fluid storage, replenishment, and thermal expansion. Coolant Pipes: Serve as channels for the antifreeze coolant and connect with the battery’s internal cooling plates to form a sealed loop. Antifreeze Coolant: Acts as the heat transfer medium. Two common layout configurations exist for the cooling unit – top-mounted or bottom-mounted on the battery pack. The expansion tank is located on the top of the battery pack. System interfaces include 1 observation window, 2 coolant ports, and 3 electrical connectors. 1.3 System Schematic and Configurations (Examples) 282 kWh Battery System (Charging or Swappable Version): Consists of four H-type modules arranged in a 2-parallel x 2-series configuration. 350 kWh Battery System (Charging or Swappable Version): Includes ten C-type modules arranged in a 5-parallel x 2-series configuration. 2. Liquid Cooling Unit: Three Thermal Circuits The battery thermal management relies on three interlinked circuits: Liquid Cooling Circuit: Electric water pump, plate heat exchanger, battery cooling channels Refrigerant Circuit: Compressor, condenser, expansion valve, plate heat exchanger Air Circuit: Electric fan, condenser There are two heat exchange interfaces: Plate Heat Exchanger: Enables heat transfer between the refrigerant loop and the liquid cooling loop. Condenser: Transfers heat between the refrigerant loop and the air circuit. Key Components and Functions Integrated Controller: This unit combines three control modules – PLC, DC-DC, and DC-AC – in one compact system. It collects data from high-pressure and low-pressure sensors, as well as inlet and outlet temperature sensors. The controller receives operational commands and target coolant temperatures from the BMS, enabling precise control over the operation of the electric water pump, compressor speed, and electric fan speed. Compressor: A core component of the refrigerant circuit, the compressor is responsible for absorbing, compressing, and discharging the refrigerant to maintain circulation. The cooling capacity of the liquid cooling loop depends on the proper functioning of the compressor. Electric Water Pump: It drives the circulation of antifreeze within the liquid cooling loop. It plays a vital role in transferring heat away from the battery cells through the liquid-cooled plates. Without proper pump operation, battery cooling cannot be achieved effectively. Electric Fan: Mounted on the exterior side of the condenser, this suction-type fan delivers continuous airflow across the condenser surface, dissipating the heat absorbed by the refrigerant. If the fan fails to operate correctly, the system may experience pressure faults due to insufficient heat dissipation. Condenser: The condenser transforms high-temperature, high-pressure gaseous refrigerant into a high-pressure liquid state. If the condenser becomes clogged or dirty, airflow is reduced, leading to decreased heat transfer efficiency and diminished cooling capacity. This results in minimal temperature difference across the coolant circuit and continuous temperature rise in battery cells, which may trigger system pressure alarms. Regular cleaning and maintenance of the condenser are essential for safe operation in electric vehicles. Plate Heat Exchanger: This component facilitates thermal exchange between the low-temperature refrigerant and the high-temperature antifreeze. After passing through the exchanger, the antifreeze temperature typically drops by 2°C to 5°C under normal operating conditions. Expansion Valve With Thermal Sensing Bulb: This valve converts the refrigerant from a medium-temperature, high-pressure liquid into a low-temperature, low-pressure liquid. The thermal sensing bulb detects temperature inside the cooling pipe and adjusts the valve’s operating accordingly to regulate refrigerant flow. Due to its high sensitivity to temperature fluctuations, the expansion valve and thermal bulb are insulated with protective layers. Sensors: High-pressure and low-pressure sensors monitor pressure levels within the refrigerant circuit. Inlet and outlet temperature sensors measure coolant temperatures at the water inlet and outlet of the liquid cooling unit. These signals are sent to the PLC controller, which uses the data to dynamically manage the operation and speed of the compressor, water pump, and fan, ensuring stable and efficient thermal regulation. Our Battery Thermal Management Solutions for Electric Semi Trucks At Brogen, we provide tailored EV battery systems along with BTMS solutions. For electric semi-trucks and other heavy-duty vehicles, we offer standard 272 kWh and 350 kWh battery systems, paired with BTMS units ranging from 5 kW to 10 kW. The thermal units feature a lightweight aluminum alloy frame and can be optionally equipped with PTC liquid heaters. They support multiple operation modes, including standby, cooling, heating, and self-circulation. Communication is based on the CAN bus protocol, with built-in self-diagnosis, real-time status monitoring, and fault reporting capabilities. In addition, we offer integrated thermal management solutions tailored to customer requirements. These systems share components, such as the compressor and condenser, between the air-conditioning circuit and the battery cooling system. The architecture includes dual evaporator circuits: one for cabin climate control and the other for battery temperature regulation. The battery cooling loop uses a secondary liquid-cooling heat exchange approach to ensure efficient and stable thermal performance. Technical Parameters Model OETLE205 OETLE207 OETLE208 OEEFDR-01 OEEFDR-02 OEEFDR-03 OEEFDR-04 Cooling capacity 5 kW 7 kW 8 kW 3 kW 5 kW

Installation Requirements for Onboard Charger (OBC + DCDC) 1. General Requirements The onboard charger layout must take into full consideration its mechanical and electrical characteristics, adhering to principles such as ease of assembly/disassembly, system size, cost minimization, and strong electromagnetic compatibility. 2. Positioning Requirements for the Onboard Charger System-level considerations: The orientation of the OBC should be determined based on its function and characteristics, especially the direction of current flow and coolant piping. Sufficient installation space: A minimum clearance of 10 mm must be maintained between the OBC and surrounding components. Proximity principle: The wiring harness connections between the OBC and components such as the charging port, PDU, traction battery, and auxiliary battery should be as short as possible. Avoid placement near areas of high temperature or excessive moisture. 3. Mounting Requirements for the Onboard Charger The OBC should be mounted in a location that allows convenient removal, preferably without the need to lift the entire vehicle. Adequate tool access space must be reserved around all mounting points. 4. Connector Position Requirements Connectors should be positioned as close as possible to the electrical components they are wired to. The space reserved in the direction of the connector should be at least three times the length of the connector itself, while also ensuring the wiring harness has a sufficient bending radius (greater than 5 times the diameter of the harness). 5. Coolant Circuit Requirements The highest point of the OBC coolant circuit should be lower than the reservoir tank. Inlet and outlet hose positions should be oriented according to the direction of coolant flow and placed as close as possible to the corresponding components. For horizontal installations, either side may serve as the inlet/outlet; for vertical installations, coolant should flow bottom-in, top-out. The OBC should be positioned upstream of the EDS in the cooling loop. 6. Crash Safety Requirements The OBC should be located away from high-risk collision zones. 7. Vibration Requirements The OBC must be positioned away from direct vibration sources such as the engine or suspension system. The vibration standard for the onboard charger (when installed on body-mounted components above dampers) is an RMS acceleration of 30.8 m/s². 8. Dimensional Chain Requirements If the OBC mounting bracket consists of multiple parts and is a newly developed component, dimensional chain analysis must be conducted, and mounting hole specifications should be defined accordingly. For existing (carry-over) parts, the design must control dimensional chain deviations to ensure the mounting hole dimensions meet installation requirements. 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 have been adopted by vehicle manufacturers in countries and regions such as Canada, Türkiye, Brazil, the Philippines, Indonesia, the Middle East, and more. Discover our Onboard Charger & DCDC solutions here: https://brogenevsolution.com/obc-dcdc-pdu/ 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 > ContactFill in the form and we will get in touch with you within 2 business days.Please enable JavaScript in your browser to complete this form.Please enable JavaScript in your browser to complete this form. Name * FirstLast Work Email *Company Name *Your Project Type *– Please select –Car, SUV, MPVBus, coach, trainLCV (pickup truck, light-duty truck, etc.)HCV (heavy-duty truck, tractor, trailer, concrete mixer, etc.)Construction machinery (excavator, forklift, crane, bulldozer, loader, etc.)Vessel, boat, ship, yacht, etc.Others (please write it in the note)Your Interested Solutions *– Please select –Motore-AxleBatteryChassisAuxiliary inverterOBC / DCDC / PDUAir brake compressorEPS / EHPS / SbW / eRCBBTMSOthers (please write it in the note)Do you have other contact info? (Whatsapp, Wechat, Skype, etc.)Please introduce your project and your request here. * Checkbox * I consent to receive updates on products and events from Brogen, and give consent based on Brogen’s Privacy Policy. Submit

HVIL Explained: What It Is and Why It’s Critical for High-Voltage Safety With the rapid development of electric vehicles (EVs), especially the increasing demand for fast charging, the operating voltages used in EVs are steadily rising. While some models still use a 200 V platform, the mainstream adopts 400 V systems, and high-end vehicles are increasingly equipped with 800 V architectures. Some OEMs are now developing even higher voltage platforms of 900 V to 1000 V to support ultra-fast 6C charging. As voltage levels increase, concerns about high-voltage safety in EVs grow accordingly. 1. Safety Challenges Associated with High Voltage The primary safety risk associated with high voltage is electric shock, particularly when high-voltage components become exposed. Besides shock hazards, two other major safety issues related to high-voltage operation are switch arcing and high-voltage power loss. 1.1 High Voltage Exposure The generally accepted safety thresholds for human exposure are approximately 50 VAC or 120 VDC. However, actual safety depends heavily on the environment, contact duration, and body resistance. For example, voltages below 36 VAC or 60 VDC are considered relatively safe in dry conditions, but in wet or conductive environments, safe voltages drop to 12 V to 24 V. Mainstream EV high-voltage systems operate around 400 VDC, far exceeding these safety levels. Exposure to such voltages presents serious risks. To mitigate this, all high-voltage components are enclosed in insulated protective covers. These protective covers must remain securely closed during vehicle operation; any unauthorized opening must be detected and addressed immediately. 1.2 Switch Arcing High-voltage switches, such as connectors, can generate electric arcs when opened or closed under load. This occurs because when the voltage exceeds the breakdown voltage of the surrounding gas or insulation medium, electrons accelerate and ionize surrounding particles, causing an avalanche effect that sustains an electric arc. Such arcs can severely damage switch contacts and pose fire hazards to nearby components and personnel. 1.3 High-Voltage Power Cutoff In traditional vehicles, power is provided by an internal combustion engine. When the engine encounters issues – such as high coolant temperature, emission faults, or operational failures – early warnings and appropriate handling are required. In electric vehicles, propulsion is driven by high-voltage electricity from the power battery to the motor. If high-voltage power is suddenly cut off while the vehicle is in motion, it can result in a complete loss of power, posing safety risks to both the vehicle and its occupants. Therefore, early warnings and safety mechanisms must be in place. Issues such as high-voltage exposure, switching arcs, and unexpected high-voltage disconnection must be detected, monitored, and handled effectively to prevent related safety incidents. The High-Voltage Interlock Loop (HVIL) is a safety mechanism capable of addressing all of these concerns simultaneously. 2. Basic Concept of HVIL HVIL stands for High Voltage Interlock Loop – a safety system designed to monitor the integrity of the high-voltage circuit using a low-voltage signal loop. It continuously checks the connection status of all high-voltage components and wiring harnesses, ensuring the entire system remains intact and safe. HVIL systems typically cover critical components such as the battery pack, Battery Management System (BMS), Vehicle Control Unit (VCU), Power Distribution Unit (PDU), Motor Control Unit (MCU), DC/DC converter, PTC heater, wiring harnesses, connectors, and protective covers. When a fault or disconnection occurs anywhere in the HVIL loop, the system triggers alarms and initiates safety measures. 3. How HVIL Works 3.1 Mechanical Structure As previously mentioned, switch arcing is a common issue in high-voltage systems during operation. In electric vehicles, the primary switches that require connection and disconnection are high-voltage connectors, namely, plugs and sockets. If these connectors are plugged or unplugged while live, arcing can easily occur. This problem is addressed through specialized mechanical design. Standard connectors typically have only two terminals: one for the high-voltage positive and one for the negative. HVIL connectors, however, include an additional pair of low-voltage terminals – positive and negative – used by the HVIL system to monitor circuit integrity. These are referred to as HVIL pins. HVIL Connectors As shown in the diagram above, the HVIL connector features four terminals, with two additional HVIL pins located in the center. The illustration on the right further shows that the contact points of the central HVIL pins are not on the same plane as those of the HV pins on either side. The HVIL pins are shorter, which means that during connection, the HV pins make contact first, followed by the HVIL pins. Connection Sequence and Disconnection Sequence The connection process proceeds from left to right: In the left image, all four pins are fully disconnected. In the middle image, the two HV pins on either side make contact first, while the central HVIL pins are not yet connected. In the right image, the HVIL pins complete the connection, finalizing the engagement of all four terminals. If the HVIL pins detect an abnormal condition, the high-voltage circuit is immediately interrupted. When the HVIL pins are not connected, the system is in an open-loop state – considered abnormal – and the internal circuit will cut off the high-voltage supply. Therefore, before the HVIL pins engage, the high-voltage circuit remains open, preventing any voltage presence and eliminating the risk of arcing. This design ensures safety during connector engagement. The disconnection process occurs in reverse order, from right to left: the HVIL pins disconnect first, followed by the HV pins. Once the HVIL pins open the circuit, the high-voltage power is immediately cut off, ensuring that when the HV pins are separated, no voltage is present – thus guaranteeing safe disconnection. 3.2 Electrical Principle While the issue of switch arcing can be addressed through specialized mechanical design, verifying the integrity of the high-voltage circuit requires an electrical solution. Sample Schematic Diagram of the HVIL Circuit The diagram above illustrates a sample HVIL system, which uses a dedicated HVIL monitoring unit. This unit is connected in series with the HVIL pins of the BMs, MDI, and OBC modules, forming a closed monitoring loop.