Pyrotechnic or Pyro Fuses can actively interrupt circuits. Just like airbag systems, pyro fuses may be a part of HV systems. Electrical designers use pyro fuses in case the electrical circuit needs to be broken via an external signal. However, pyro fuses can also interrupt the circuit during events where current flow is higher than the current limit.
When the signal is detected from the vehicle, an ignition current is generated to operate the Pyro-Fuse, shutting down the circuit and preventing electrical flow [1].
The ignition current is generated based on the ECU signal.
Vehicle BMS, battery management systems, or collision sensors detect short circuits or crash signals.
A low-voltage pulse (typically 3–12V, lasting around 2ms) is sent to the Pyro Fuse controller.
The initiator ignites an explosive element.
The ignitor heats up within milliseconds, detonating the built-in gas generator, producing a shockwave or high temperature to sever the fusible element.
The pressurized piston detaches the busbar, shutting down the electric circuit.
Images from: Pyro-Fuse, Volt Breaker by DAISI
Benefits and Applications
There are a number of benefits and applications [2]:
- Primary Circuit Protection: Instantly cuts off battery high-voltage outputs in the event of short circuits, collisions, or thermal runaway, safeguarding both personnel and equipment.
- System Isolation: Works alongside mechanical relays or main contactors to physically isolate main circuits.
- Ultra-Fast Response: Typically under 1ms, much faster than traditional fuses or contactors.
- Redundant Safety Mechanism: Acts as secondary protection if the main contactor fails.
- Intelligent Safety Integration: Some advanced products support CAN or LIN communication, providing real-time fuse status feedback to the main control system.
However, the fuse cannot be reset without being replaced. Hence these are normally used in conjunction with normal electromagnetically actuated contactors.
References
- Pyro-Fuse, Volt Breaker by DAISI
- Global Pyro Fuse Supplier Landscape and In-Depth Competitiveness Analysis, HIITIO