Sensata’s Disconnect Solution Enables Faster and Safer EV Charging
The new unit from Sensata Technologies combines an electromechanical contactor and a fuse in a single module package.
EV charging systems will need to pump out an incredible 350 kilowatts, and if something goes amiss, the power needs to be controlled or disconnected — fast. The relay-like contractors provide flexible power control, while the fuse works within a partnership, providing cutoff in the event of a short circuit.
Image courtesy of Sensata Technologies
Sensata’s solution combines the contactor and the fuse, in one single module. Present-day practice is for separate units, leaving designers with the tricky task of making sure the two units don’t work at cross purposes to each other.
As explained in a White Paper written by Sensata’s Markus Beck, in this context, fuses are designed to fail (melt), and permanently end any current flow as a result of the high temperature caused by a short.
The problem is that as charging progresses, there will not be a steady-state current level. Thus, very high current fuses must be chosen to avoid what can be described as “nuisance tripping.”
Very much like relays or circuit breakers, contactors are externally controlled and resettable.
The GIGAVAC from GigaFuse is a fast-acting electromechanical unit that trips the power circuit at exact, specified currents. Image courtesy of Sensata’s White Paper
Contactors are also much more robust than relays, and, importantly, are specifically designed to suppress the voltage arcs that can be generated by switching.
Fuses and Contactors Working Together
The image below illustrates the operation of a 500 amps contactor and a 500 amp fuse. Note that the solid blue portion indicates normal operation. The solid blue line illustrates when the GigaFuse disrupts current. Due to intelligent control, it can come very close to the normal operating range. The dashed, dark blue line represents the action points for the fuse.
Operation of Contactors and Fuses. Image courtesy of White Paper
As can be gleaned from the above diagram, at 1,000 amps, it would take about 10 seconds for the 1000 amp fuse to act, but it would take about 3 microseconds for the GigaFuse.
It should also be mentioned that the GigaFuse features 0.15 milliohms contact resistance. This will mean lower power losses and increased efficiency.
The Perils of Incorrect Pairing
As the contact begins to break a circuit, it can begin to dissipate some of the over-current within itself. That current would not be available to properly disrupt the fuse, and the result could be a catastrophic failure of the entire system. Sensata’s disconnect solution, where both elements are specifically engineered to work with each other, removes that risk.
Accepted by Manufacturers
In the press release, Sensata mentions that “Several leading infrastructure OEMs are using Sensata’s new contactor module for a safer, more comprehensive power disconnect solution in DC fast charging applications.”
Nick Moelders, Vice President, Electrification at Sensata Technologies expounds on to state that, “Our recent wins with major Charging Infrastructure OEMs demonstrate the added value we provide to our customers as we move from being a component supplier to a leading electrification solutions provider. Working engineer-to-engineer with the most innovative companies allows us to learn and adapt to the needs of the rapidly transforming clean energy market.”
About Sensata Technologies
Sensata Technologies is a leading industrial technology company that develops sensors, sensor-based solutions, including controllers and software, and other mission-critical products to create valuable business insights for customers and end-users. For more than 100 years, Sensata has provided a wide range of customized, sensor-rich solutions that address complex engineering requirements to help customers solve difficult challenges in the automotive, heavy vehicle & off-road, industrial, and aerospace industries. With more than 19,000 employees and operations in 13 countries, Sensata’s solutions help to make products safer, cleaner and more efficient, more electrified, and more connected. For more information, please visit Sensata’s website at www.sensata.com.