Different types of fuses in electric vehicles vary in structural characteristics and protection logic, making them suitable for distinct circuit scenarios. They are as follows:
1. Fast-Acting Fuses
Core Features: Extremely fast melting speed (typically in milliseconds), high sensitivity to transient overcurrent, and ability to rapidly disconnect the circuit during a short circuit or sudden overload.
Applicable Scenarios:
Power battery main circuit: Directly connected in series with the high-voltage battery output. In the event of a battery short circuit (e.g., a collision causing positive and negative terminals to contact), the fuse disconnects the circuit before an arc forms, preventing battery fires.
Motor controller input circuit: A motor may generate short-term current spikes during startup, but fast-acting fuses only respond to sustained overcurrent, protecting the controller from short-circuit damage.
DC-DC converter high-voltage side: If an internal short circuit occurs in the converter, fast-acting fuses can quickly isolate the fault to avoid affecting the battery pack.
2. Slow-Blow Fuses (Time-Delay Fuses)
Core Features: Allow short-term overcurrent (such as starting current) to pass through but only respond to sustained overcurrent (1.5–2 times the rated current lasting several seconds), preventing false protection triggers.
Applicable Scenarios:
Onboard Charger (OBC) input circuit: Initial charging may involve a surge current, and the slow-blow feature tolerates this process. It also activates during sustained overcurrent caused by internal charger faults.
High-voltage air conditioning compressor circuit: Compressor startup current peaks are high (approximately 3–5 times the rated current). Slow-blow fuses avoid false triggering during startup and only trip during sustained overloads (e.g., compressor jams).
PTC heater circuit: Heaters have high power and large current fluctuations during startup, so the slow-blow design matches their operating characteristics.
3. Blade Fuses
Core Features: A flat, blade-like structure enables compact size, easy installation, and low contact resistance, making them suitable for low-voltage, low-current circuits.
Applicable Scenarios:
12V low-voltage auxiliary systems: Such as in-vehicle entertainment systems, lighting, and wipers, which typically have rated currents of 5–30A. The compact design of blade fuses saves installation space.
Low-voltage control circuits: Including low-voltage power supplies for BMS (Battery Management Systems) and coil power supplies for high-voltage contactors. These require quick replacement and handle small currents, aligning with the characteristics of blade fuses.
4. Bolt-On Fuses
Core Features: Bolt-on fastening provides a large contact area, high current-carrying capacity (up to several hundred amperes), and high mechanical strength, making them suitable for high-voltage, high-current circuits.
Applicable Scenarios:
High-voltage distribution box main circuit: This connects the battery to various high-voltage components and must handle continuous currents of several hundred amperes. Bolt-on fastening ensures low contact resistance and vibration resistance.
Fast-charging interface circuit: Currents can exceed 100A during fast charging. Bolt-on fuses withstand the heat generated by high currents and reliably disconnect in case of an interface short circuit.
