By Laird Technologies, Inc.

According to a Mobility Report from Ericsson, there will be 6.1 billion smartphone users by 2020, or about 75% of the world’s population at that time. Today, it is estimated that there are 2.6 billion smartphone subscriptions globally. As a result, the mobile communications industry is moving faster than ever to keep up with the way we use mobile devices. This includes delivering the connected experience of video, voice, and data to the billions of people worldwide who are eager to consume it.

The industry has seen the escalating use of smartphones and other mobile devices transform network traffic from mostly voice to a mix of integrated voice, video, and data. There has also been a massive expansion of network coverage as people expect access to their content everywhere they go.

For example, most people today cannot imagine driving without their smartphones. Recent studies show that seven out of 10 people use their smartphone while driving. Beyond placing a call, mobile phones deliver more functionality than ever before. Cell phones offer GPS navigation, infotainment (podcasts, internet radio, and playlists) options, voice-controlled texting, customization of vehicle setting (air conditioning and seat positions), as well as data transfer with the cloud. They are also essential for using apps from the vehicle manufacturer. The use of cell phone and other mobile devices is so prevalent that many car manufacturers now offer WiFi in the vehicle.

This mass expansion of cell phone usage requires a significant amount of send/receive data, and the more data a phone transfers, the shorter the battery life. In addition to the increased use of WiFi-connections and apps, the enhanced physical size and quality of displays drain batteries faster than ever. Ten years ago, a fully charged cellular phone battery would last around a week. Today, the average battery life for a smartphone is one day. And this doesn’t even account for the expansion of LTE and LTE-Advanced networks that utilize more power than ever before.

The continuous usage of a smartphone during daily life requires more power, increasing the risk of experiencing a dead battery. This makes vehicle charging an even more important event in the daily life of consumers

Inductive charging — a proven technology

Charging a smartphone in the car is a truly antiquated and inconvenient process — connectors do not always fit, adapters can be lost, cables get tangled, connecting while driving can be a dangerous undertaking, and the charging capacity of the USB connector is low. The obvious solution is a technology that the inventor and visionary Nikola Tesla had already demonstrated in 1891: the wireless “inductive” transfer of energy for lighting incandescent bulbs.

Inductive charging — as in the wireless transfer of energy between an electric toothbrush and its base station, for example — converts an input voltage into a constant output voltage, the same way a standard combinatorial circuit component functions. The key difference is the power supply unit: the wound coils used in the power supply unit are installed separately in wireless charging. A magnetic field is created from a precisely defined frequency between 105 kHz and 205 kHz via the coils in the transmitter modules; the coils in the receiver devices receive electrical power with the identical frequency and generate the voltage that charges the device’s battery.

Challenges with wireless charging systems

The development and implementation of wireless charging systems do not come without significant design challenges. Electromagnetic Compatibility (EMC) requirements in automotive applications are stringent, and rightly so. EMC is the unintentional generation, broadcast, and reception of electromagnetic energy that can cause unwanted effects on an electrical system such as electromagnetic interference (EMI).

Wireless charging can have a negative influence on the KeyFob system by generating these unwanted electromagnetic fields that interfere with KeyFob performance. With the evolution of the KeyFob system to now include vehicle door lock/open, trunk open/close, and critical remote engine start, it is vital that a wireless charging system does not emit EMC that interference with the keyless go system. The design challenge is intensified when the driver places the KeyFob on or near the wireless charging station. For example, when the KeyFob is on the wireless charging station/platform during charging, the vehicle couldn’t find the KeyFob signal, and thus the car would not start or operate. The development of advanced EMC shielding techniques is essential to ensuring the coexistence of the wireless charging system with KeyFob and other critical car key communications.

Extreme temperatures not only have an adverse effect on a mobile device but on the wireless charging station as well. The typical operating temperature for a cell phone is 0° C to 35° C. The interior of a vehicle sitting in a sunny parking spot during the summer can reach well beyond 37° C. During a winter day, the temperature can reach well below 0° C. When not appropriately designed and protected, these drastic temperature changes throughout the year can lower the performance of the charging system, and cause damage that renders it inoperable.

EMC and temperature fluctuations can also affect the efficiency of the wireless charging system. When transferring power from the platform to the phone, some energy will inherently be lost; however, many wireless charging systems can only achieve efficiencies of around 45% under perfect conditions. EMC shielding and thermal management play an important role in increasing the energy efficiency of the system.

Wireless charging modules’ charging times are also dependent on the distance between the transmitter and the receiver module. Laird has designed units to bridge distances up to 4 millimeters. Greater distances are possible, but only at a higher transmitting power level, which in turn would negatively affect the critical electromagnetic compatibility (EMC) in a closed vehicle. The EMC value indicates the undesirable fact that technical devices disrupt each other through electrical or electromagnetic effects.

With thousands of distinct smartphone models in existence worldwide, there is no single wireless charging design that can effectively power every model. The battery area on many of these phones is different, and the wireless charging system must be able to work with every version, no matter what the phone position is at the charging station. Also, every vehicle interior is different, including ergonomic design and electronic functionality. The need for a single platform that is easily and cost-effectively customizable to meet every vehicle’s specific design requirement is mandatory.

Current communication protocols

To achieve maximum device coverage, the Wireless Charging Units by Laird feature hardware to meet the broadest possible requirements. The only limitations are set by the currently used communication protocols: two consortiums competing for the wireless charging standard. “Qi” (pronounced “Chee”) currently possesses a broader distribution range. Qi is part of the Wireless Power Consortium (WPC), a protocol that has been on the market since 2008 and unites more than 200 companies, including Microsoft, Samsung, Sony and almost all Android smartphone providers. The “Consumer Electronics for Automotive” (CE4A) Group represents the leading car manufacturers such as BMW, Audi, and Daimler and has set “Qi” as the common standard.

Both Alliance for Wireless Power (A4WP) and the Power Matters Alliance (PMA) are competitors, the latter of which connects consumer users like Starbucks and manufacturers such as HTC, Blackberry, and Duracell. Both organizations have been working closely together since January 2015.

The PMA represents mobile device manufacturers, mobile service providers, and hardware manufacturers and uses its own software protocol “Powermat,” while A4WP uses a third proprietary protocol. So far, there are no plans to merge these two standards; they will continue running parallel to one another despite the close cooperation between PMA and A4WP.

Although many smartphone models are made for wireless charging directly from the production line, not every model complies with Qi. In the near future, when consumers are selecting a next-generation smartphone, a decisive factor may be which device can use wireless charging irrespective of transfer protocols.

Currently, the Wireless Power Consortium (WPC) is operating in working groups (such as the Automotive Application Group) to develop another protocol that takes the EMC problem into account. It is also working on wireless charging with the “Qi” protocol, which makes charging over an initial distance of around 50 millimeters possible.

A growing technology

Wireless charging is seen as a commodity in the automotive sector. The vehicle is perceived as a living space, and for 2.6 billion people, smartphones have become an indispensable companion in nearly every aspect of life. This has resulted in the need for OEMs to design smartphone integration as conveniently as possible in the automotive environment. Wireless charging is the response to this market demand.

Yet while wireless charging in vehicles is becoming an available component for connected car solution, its development keeps on progressing. Future device generations will be able to charge multiple devices simultaneously and have downward compatibility in the next two to three years. In addition, other devices are to be used inductively — devices with irregular, non-planar 3D surfaces such as game consoles, cameras, toys or wearables such as watches are also all conceivable.

A particularly exciting development for the wireless charging market, especially in the automotive sector, is the integration of the Near Field Communication (NFC) standards that make other applications possible that have traditionally required high data security. By integrating NFC, wireless charging technology can also be used for authentication, which opens up many more possibilities for use in the connected car. Some examples are the automatic termination of a rental transaction for car sharing, automated payment processes, such as downloading the most current and additional card information or augmented reality information.

Wireless charging solutions with high-quality standards that provide OEMs the flexibility to develop unique solutions and are convenient for the user are essential.

You can download the complete white paper from Laird Technologies here.