The cars we drive today are different from the cars of yesteryear. Some of the features that our vehicles now include would make some of our ancestors faint.
Not only are the features improving though, the way a car functions has drastically changed.
Now, cars are basically computers on wheels. Nearly every system in a car is monitored or optimized by technology, including sensors. This is particularly evident in electric vehicles (EVs).
Because of the nature of what a car is today, electromagnetic interference (EMI) is a much greater issue. Before, the only electrical interference in an older car you had to deal with was a bit of static on the radio when you drove near power lines. Today, the very components that make up your car can now cause EMI.
In the rapidly evolving world of EVs, ensuring electromagnetic compatibility (EMC) is crucial for optimal performance and safety.
THE IMPACT OF EMI ON 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.
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 EMC-protected automotive sensors, EMI can lead to significant issues, from minor malfunctions to complete system failures. A malfunctioning sensor can trigger a chain reaction, affecting other systems. For instance, managing battery temperature is essential for optimal performance. If the sensors that track heat levels fail, thermal management systems might not activate. This can result in excessive heat, which could compromise EMI shielding and pose severe safety risks, including thermal runaway.
Sources of EMI in EMC Electric Vehicles
Each time an electric vehicle is powered on, it generates EMI. Key components responsible for EMI in EVs 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.
EMI SUPPRESSION TECHNIQUES FOR AUTOMOTIVE SENSORS
Sensor manufacturers are using multiple methods to provide EMI suppression 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, where two conductors of a single circuit are twisted together. This approach improves electromagnetic compatibility (EMC) in automotive components and reduces EMI, while also providing additional shielding from external electromagnetic interference.
ENSURING SAFE OPERATION OF EVS
EVs have made significant strides, with today’s engineering innovations leading to a new era of highly efficient electric vehicles that are transforming the automotive industry.
However, these advancements have also heightened concerns about electromagnetic interference, particularly due to its potential impact on sophisticated electronic systems.
Strong electrical shielding, efficient power and temperature management, and advanced sensors are essential for controlling electromagnetic emissions and ensuring the safe operation of EVs.
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How do manufacturers test and measure the effectiveness of EMI suppression techniques in automotive sensors? Manufacturers test and measure the effectiveness of EMI suppression techniques using a combination of laboratory testing and real-world simulations. Laboratory tests involve subjecting sensors and other components to controlled electromagnetic environments to assess their performance and identify any weaknesses. This is often done using specialized equipment such as anechoic chambers, which can isolate the device from external EMI sources. Additionally, manufacturers perform real-world simulations by installing sensors in test vehicles and evaluating their performance under various driving conditions. This helps ensure that the suppression techniques are effective across different operational scenarios and environments. The long-term effects of EMI on electric vehicle components can be significant, potentially leading to gradual degradation of electronic systems. Over time, persistent EMI can cause wear and tear on sensitive components, leading to reduced reliability and functionality. For instance, continuous exposure to EMI may result in the gradual breakdown of insulation materials or interference with electronic circuitry, which can eventually lead to component failure. This deterioration might not be immediately apparent but could affect the vehicle’s performance and safety over its lifespan. Different electric vehicle designs can influence the level and management of EMI in various ways. For example, EVs with high-capacity battery configurations or multiple motors may generate different levels of electromagnetic emissions compared to simpler designs. Battery configurations that involve high-power densities or fast-charging capabilities can increase EMI, requiring more robust shielding and suppression techniques. Similarly, different motor types, such as those using different switching technologies or operating at various frequencies, can impact EMI levels. Manufacturers must tailor their EMI management strategies to the specific design and components of each EV to ensure effective control and suppression of electromagnetic interference. |
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