As the core part of ensuring electrical safety, high voltage fuses are suitable for the following kinds of situations. The design features and functions of the high voltage electrical system which is closely related to new energy vehicles require that:
I. Core Protection Scenarios
Main circuit protection
Battery charge-discharge protection: If the current exceeds the safety threshold (e.g. continuous overload or short circuit) during the battery charge-discharge process, the high-voltage fuse will melt rapidly, preventing the battery from overheating, catching fire or exploding. For example, when the battery management system detects an abnormal current, the fuse can cut the circuit in milliseconds to prevent damage to battery pack.
Drive circuit protection: The motor controller of an electric vehicle (such as an inverter) needs to handle high power currents. Fuses can prevent the motor blockage, short circuit and other faults caused by the current fluctuation, and protect the motor and controller from damage.
Auxiliary circuit protection
Air conditioning System: High voltage power supply is required for compressors, PTC heater and other Auxiliary equipment for electric vehicles. Fuses prevent short-circuit circuit currents caused by equipment failures from affecting the entire vehicle's electrical system.
DC/DC converter: When converting a high voltage DC to a low voltage DC (e.g. charging a a 12V battery), the fuse protects the converter from damage caused by a short circuit or overload of the input/output terminals.
Charging system: During fast charging or slow charging, the fuse can prevent short circuit or overload of the charging pile or the car charger caused by the high voltage circuit failure, to ensure safe charging.
High voltage wire harness protection
If a high-voltage wire harness in an electric vehicle (such as a cable connecting a battery, motor and charging port) short-circuits due to aging, wear or impact, the fuse can quickly cut the current to prevent the wiring harness from catching fire or causing arc damage to other components.
II. Adapting to Special Scenarios
800V high-voltage platform
When an electric vehicle is upgraded to a voltage platforms of 800 V or higher, a high-voltage fuse needs to be more pressure-resistant (usually covering 500V-1000V) and breakable (up to 10 kA) to cope with a surge in short-circuit current at high voltages. In an 800V system, for example, a fuse needs to cut several thousand amperes of electricity during a short circuit to prevent the system from collapsing.
High Frequency Pulse Tolerance
High-frequency current pulses are generated when the motor startup and battery charges and discharges. Fuses need to have shock resistance to prevent false fuses caused by pulse currents. For example, if the motor starts and stops frequently, the fuse needs to withstand short-term overload without damaging.
Adapting to extreme conditions
Temperature adaptability: Fuses need to operate steadily in a wide temperature range of -40°C to 85°C, adapting to extreme conditions such as high temperature charging and low temperature start-up.
Vibration and impact: The vibration and impact of electric vehicles during operation will cause mechanical stress to the fuse, which must be protected by anti-vibration design.
III. Typical Application
Passenger car
New energy passenger vehicles typically require four to 8 high-voltage fuses to protect the main circuit (e.g. battery, motor), auxiliary circuit (e.g. air conditioning, DC/DC) and charging system.
Commercial vehicles
New energy commercial and specialty vehicles require more fuses (e.g., 8-16) because of their higher power demands. For example, a high-voltage system for an electric passenger car could consist of a main fuse, an auxiliary fuse and a charging fuse, forming a layered protection structure.
Charging pile
The output end of the DC charging pile needs to be equipped with a high voltage fuse to protect the charging module and the vehicle charging port.
