Demystifying EV Charger Design

As we embrace greener transportation, the advantages of electric vehicles (EVs) are becoming increasingly apparent. But for EVs to truly succeed, one crucial factor is ensuring that EV drivers can charge their vehicles conveniently, whether at home or on the go. This is where EV charger design comes into play, encompassing everything from where chargers are located to how they function , their safety features, and even their aesthetics.

?Where do electric vehicles get charged?

Electric vehicles are typically charged at two types of locations: destination chargers and en-route chargers.

Destination chargers are usually found at places like parking lots, shopping centres, or residential garages. These chargers use slow AC charging, often allowing for overnight charging when electricity rates are lower. Some of these chargers come with built-in cables, while others require the driver to use their vehicle's portable cable.

On the other hand, en-route chargers are situated at places like gas stations along highways. These chargers utilise high-power, fast DC charging, significantly reducing charging times.

Understanding charging standards and speeds

EV chargers are categorised into three main levels:

• Level 1 (Residential): These chargers are typically installed at homes, allowing for overnight charging. They often use off-peak electricity and can be either built-in or portable. Many businesses are also installing these chargers for their employees.
• Level 2 (Commercial): Commercial chargers, also known as fast chargers, are commonly found in public places. They provide faster charging than Level 1 chargers and are usually wall-mounted or post-mounted. Charging times may vary, but many drivers use them for quick top-up charges.
• Level 3 (Rapid Charger/On-the-go): Rapid chargers deliver charge at an even higher current, significantly reducing charging times. However, they are more expensive to install and require a higher-capacity electrical connection. They are often seen at places like petrol stations and resemble traditional petrol pumps.

Designing efficient and reliable EV chargers

EV charging solutions are multifaceted, requiring tailored designs rather than one-size-fits-all solutions. Although charging stations vary in layout between homes and gas/petrol stations, they share many components . Designing a user-friendly, efficient, and visually appealing charging station is paramount.

With the increasing demand for fast-charging stations, along with the desire for higher power levels, EV charging system designers must focus on enhanced efficiency, dependability, and safety.

Efficiency: Reducing carbon emissions primarily motivated the shift from fossil-fuel-powered vehicles to EVs. EVs not only reduce pollution but also enhance efficiency and performance. However, suitable infrastructure and a well-organised charging station solution are crucial to capitalise on this technology. Charging at home is convenient, but DC charging stations significantly speed up the process by minimising power conversion losses, resulting in quicker charging speeds.

Power semiconductors play a crucial role in this process. They convert alternating (AC) electricity into direct (DC) power required to recharge a vehicle's batteries. Managing the charge level incurs power losses in the form of heat. To mitigate these losses, sophisticated devices based on SiC and GaN technologies provide ultra-fast switching, resulting in lower power losses compared to silicon devices.

?Reliability: Installing a DC charger requires significant time and financial investment. Ensuring these chargers can withstand extreme weather conditions and have a long lifespan is crucial. High-quality components and preventative measures, such as fuses for overcurrent protection, improve overall system dependability.

Semiconductors, primarily made of silicon or silicon carbide, are vulnerable to electrical dangers. Fuses must protect them from overcurrent. Specialised high-speed DC fuses are necessary to safeguard power converters from overcurrent, ensuring the proper functioning of components like MOSFETs, IGBTs, thyristors, and diodes.

Another threat to sensitive semiconductors is overvoltage. Protection against voltage spikes is essential, especially near industrial facilities with large motors or areas prone to lightning strikes. Overvoltage protection prevents damage to charger components from electromagnetic radiation and voltage spikes.

Safety: Safety is a primary concern in EV charging, particularly with the high voltages involved. DC charging poses a higher risk of electric shock due to voltage levels ranging between 400V and 1000V. Ground-fault protection systems prevent electric shock by instantly shutting off power in case of a fault.

Circuit protection is vital in DC charging. Various devices, such as High-power Transient Voltage Suppressor (TVS) diodes or metal oxide varistors (MOVs), provide protection against transient voltage spikes. Understanding the activation time of these protectors is critical to shield sensitive circuits effectively.

?Grid Integration: EVs can act as energy consumers and suppliers, returning stored energy to the grid during high demand or power outages. The bi-directional flow of electric energy between vehicles and the power grid characterises this technology, known as the vehicle-to-grid system.

Robust communication systems in EV charging stations enable safe and secure data interchange between the car, the grid, and the cloud. Compliance with standards like ISO 15118 ensures grid integration and long-term design flexibility.

Choosing the best connectivity option depends on the use case, installation environment, and grid integration requirements. Commercial chargers often require cloud connectivity for invoicing and data insights, while residential chargers should integrate with existing networks in smart houses.

The Open Charge Point Protocol (OCPP) facilitates data interchange over Ethernet, cellular, Wi-Fi?, or Sub-1 GHz signals. Chargers should offer various connection options to fulfil OCPP flexibility criteria, ensuring robust connections and network compatibility in various conditions.

?Metering: Accurate metering of energy consumption is essential for billing, monitoring, and optimising charging infrastructure. Secure communication protocols and encryption ensure the integrity and confidentiality of metering data. Additionally, tamper detection mechanisms help identify and prevent unauthorised tampering with metering devices.

?Security: Ensuring the security of EV charging infrastructure is critical to protect against cyber threats and unauthorised access. Robust security measures are necessary to prevent tampering, data breaches, and malicious attacks.

Authentication mechanisms, such as secure access controls and encryption protocols, safeguard communication between the vehicle, charging station, and backend systems. Secure firmware updates and remote monitoring capabilities help maintain system integrity and address vulnerabilities promptly.

Physical security features, including tamper-resistant enclosures and secure locking mechanisms, prevent unauthorised access to internal components. Regular security audits and compliance with industry standards ensure ongoing protection against emerging threats.

By prioritising efficiency, reliability, safety, security, and metering accuracy, EV charger designers can deliver robust, resilient, and transparent charging solutions, contributing to the widespread adoption of electric vehicles.

Future Trends and Innovations

The landscape of EV charger design is evolving with technological advancements. Emerging technologies such as wireless charging and solid-state transformers offer even higher efficiency advantages. AI-driven charging process optimisation ensures chargers respond to user demands and grid circumstances more effectively. The continuous advancement of charging standards and interoperability will significantly impact the future of high-efficiency charging.

Conclusion

The number of EV chargers is expected to grow significantly, but meeting specific criteria is essential to gain the confidence of both charge point operators and users. By prioritising safety, efficiency, usability, connectivity, and accurate billing, EV charger designers can ensure the success of their products and contribute to the growth of the overall EV market.

We have partnered with various suppliers offering a wide range of EV charging solutions , from off-the-shelf EV charging stations to solution bundles and reference designs. Our extensive assortment of EV solutions enables accelerated time-to-market with reduced complexity and lower expenses while ensuring extended product lifecycles.

Explore our latest EV Charger Design Hub to discover the possibilities of EV chargers - learn about public charging networks, EV model guides, and much more. From the latest news, featured stories, and case studies to whitepapers, application notes, and a wide range of design solutions; you will find everything you need to know about charging .