Think about your first car.
How many bells and whistles did it have? It’s probably a far cry from the vehicles rolling off assembly lines now and what’s coming next.
In a sense, cars are now mobile computers. In modern automotive design, there is hardly a system that’s not monitored or optimized by technology – sensors included. There’s no vehicle type where this is more apparent than in electric cars.
The only electrical interference you likely had in that first car was a bit of static on the radio when you drove near power lines. That’s not the case with electric vehicles, which need additional protection against electromagnetic interference (EMI).
System Failure: How EMI Impacts Electric Vehicles
Engineers are very aware of the potential for disruption to electronic equipment by EMI and assess electromagnetic compatibility (EMC) and electromagnetic susceptibility of components carefully. When a device malfunctions, electromagnetic coupling can occur. EMI in electric vehicles can thus interfere with devices, such as sensors and the systems they monitor. management.
Sensors are crucial to monitoring an EV’s systems to make sure they are functioning properly throughout an EV. High-end EVs may contain more than 100 individual sensors to monitor and regulate temperature, pressure, and operation of components.
Without these EMC-protected automotive sensors, EMI can cause serious problems ranging from slight malfunctions to outright system failures. If the sensor isn’t functioning properly, it can create a rapidly cascading impact as other systems fail. For example, controlling heat in a battery is crucial to operating at peak efficiency. If sensors monitoring heat levels fail, thermal management safeguards might not kick in. Excessive heat can cause EMI shielding to fail and also lead to even more serious safety concerns, such as thermal runaway.
Sources of EMI in EMC Electric Vehicles
Every time a driver turns on an electric vehicle, it becomes a source of EMI. Some of the main EV components that produce EMI include:
- EV Motors: Operating at high power levels produces electromagnetic emissions. Variations in temperature and magnetic shield strength can impact the magnitude of the transformer effect.
- Power converters: Power converters are often the main source of any EMI within drive systems. These high-speed switching devices typically work at frequencies from 2 to 20 kHz, although fast insulated gate bipolar transistors (IGBTs) can operate up to 50 kHz or above.
- Cables/Wiring: Cables carry high-level current between subsystems and can also generate significant magnetic fields. Because of limited space, cables and wiring are mounted in proximity to each other and around other components, which can cause electromagnetic interference if not shielded properly and monitored
It’s also worth noting the EV charging stations are a source for EMI as well as the vehicle’s charging ports.
Protecting Electric Vehicle Sensors from EMI
Sensor manufacturers are using multiple methods to provide EMI shielding for sensors, such as using acrylic-based sprays or coatings and high-performance polymers to create EMI-resistant enclosures. Plated polymers also incorporate metals such as copper, silver, nickel, or a combination of metals to reflect interference internally.
Another common practice is using twisted pair cables or wires. Two conductors of a single circuit are twisted together to improve EMC in automotive components and reduce EMI. This also helps provide additional shielding from external electromagnetic interference.
EMI Suppression in EVs
We’ve come a long way from your first car. Today’s engineering capabilities have created a new generation of efficient electric vehicles that are changing the automotive industry. With these advancements, however, electromagnetic interference has become an even greater concern with electric vehicles because of the potential impact on advanced electronic systems.
Strong electrical shielding, efficient power and temperature management, and sensors are crucial in managing electromagnetic emissions and making sure EVs operate safely.
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