Increased energy demands on mobile devices are driving the need for new ways to manage battery life. Wireless charging provides such an opportunity by creating a common charging platform for a range of devices and offering an infrastructure to support it. Apart from mobiles, networks modules also needs wireless battery charging and charge controlling at different stages. This article will show up some available technologies and products in wireless battery charging.
Isn’t it became very common that your phone runs out of power at the most inconvenient times. With the extended applications of your mobile phones like GPS navigation, IoT connectivity, 3G and 4G access and entertainment purposes, you will want your phone always charged and ready. Actually we rely heavily on our mobile devices to provide information and simplify our daily lives, creating increased dependency on them. For this relationship with our mobile devices to be effective, they have to remain powered while we use them. However, opposing forces, such as the need for increased feature density, larger screens, and more wireless connectivity strain these devices’ power reserves. While manufacturers design ever larger batteries for their mobile phones, this benefit is effectively canceled out by new and enhanced features. New methods of dealing with short battery life have to be addressed. May be you can carry a back-up battery bank with you or better you can have wireless charger in public places like Wi-Fi and charge your phone, whenever and wherever you want. So here we go with the wireless charging technologies and solutions available today. Wireless power has the potential to help alleviate dead battery conditions, especially in situations where it matters most – in public spaces and while we’re on the go, such as in the car. Wireless power transmission was first demonstrated by Nikola Tesla in 1893, as he transferred energy wirelessly to light phosphorescent lamps. While his experiments obviously did not lead to the proliferation of transmitting power wirelessly, the foundations for wireless power were built over 100 years ago. It wasn’t until the late 2000s that wireless power would again be a mainstream topic of discussion. Companies began commercializing products that could wirelessly charge mobile devices. In the beginning, these products consisted of bulky mobile phone adaptor sleeves which contained a wireless charging receiver. The wireless charging transmitter had to be bought and would only work with certain wireless charging receivers. Soon, several companies were commercializing their own unique wireless charging products, none of which were interoperable. In 2008, the first organization was formed to try and develop a common wireless charging standard. The Wireless Power Consortium began to develop a standard it called “Qi”, pronounced “Chee.” The goal was to create a unified standard where member companies could develop their products for all types of markets, and for which the mandate was interoperability. Fast forward to 2014, and the market now has three competing standards, and a mobile phone market with a high rate of adoption. The need for bulky add-on sleeves has decreased, while more and more OEMs integrate the receiver technology into their mobile devices. While the competing standards have created some temporary market disruptions, a unified standard will eventually provide a clear path for deploying wireless power technology. For this technology to be truly transformative, though, wireless charging has to be pervasive and available everywhere. This next phase means that the public infrastructure now must adopt wireless charging stations in order to provide the full benefit this technology offers. Airports, restaurants, coffee shops and hotels will all one day offer wireless charging stations for their customers. Since mobile devices will already have the technology embedded, charging will become as trivial as placing it down at a charging station. This, in turn, will promote what I call opportunistic charging behavior. Users will have apps on their phones that guide them to the nearest charging station. No matter where we are, we will be able to receive some power for our mobile device, thereby avoiding dead battery conditions all together. Whether at a restaurant or sitting on an airplane, placing your mobile device down on a wireless charger will become second nature. Just as Wi-Fi grew into a ubiquitous technology over time, wireless power is expected to follow suit in the foreseeable future. Apart from mobile phones, wirelesses charging will help serving applications like, Wearable, Dry Batteries, Automotive Console Charger, handheld Radios, Electronic Point-of-Sale (ePOS) Terminals, Portable Scanners, Power Tools, Portable Instruments, and Portable Medical Devices etc.
Commercial Solutions available
Since wireless charging is an urgent call in many areas like, IoT wearable etc, many global players are coming up with innovative products and solutions to support the consumer requirements. STMicroelectronics offers, STWBC digital controller for wireless battery charger (WBC) transmitters for flexible and efficient solution for controlling power transfer from a WBC transmitter (TX) to a receiver (RX) in WBC-enabled phones, wearables, and other battery-powered devices that uses electromagnetic induction for re-charge. As a member of the Qi Wireless Power Consortium and the PMA (Power Matters Alliance), ST ensures full compatibility with these leading wireless-charging protocols and is one of the first companies that hold certification for the newest Qi 1.1.2 A11 standard. The STWBC performs all the essential functions for transmitter control: it is able to precisely control the amount of transmitted power to match the requirements of the receiving unit in terms of maximizing the efficiency of the power transfer and minimizing any increase in operating temperature. The digital feedback between TX and RX units also allows the detection of metal objects close to the receiver (foreign object detection FOD) that could result in potential hazards, enabling the STWBC to stop power transmission when such objects are detected. Another product is LTC4120/LTC4120-4.2 – Wireless Power Receiver and 400mA Buck Battery Charger. The LTC®4120 is a constant-current/constant-voltage wireless receiver and battery charger. An external programming resistor sets the charge current up to 400mA. The LTC4120-4.2 is suitable for charging Li-Ion/Polymer batteries, while the programmable float voltage of the LTC4120 accommodates several battery chemistries. The LTC4120 uses a Dynamic Harmonization Control (DHC) technique that allows high efficiency contactless charging across an air gap. The LTC4120 regulates its input voltage via the DHC pin. This technique modulates the resonant frequency of a receiver tank to automatically adjust the power received as well as the power transmitted to provide an efficient solution for wirelessly charging battery-powered devices. Wireless charging with the LTC4120 provides a method to power devices in harsh environments without requiring expensive failure-prone connectors. This allows products to be charged while locked within sealed enclosures, or in moving or rotating equipment, or where cleanliness or sanitation is critical. This full featured battery charger includes accurate RUN pin threshold, low voltage battery preconditioning and bad battery fault detection, timer termination, auto-recharge, and NTC temperature qualified charging. The FAULT pin provides an indication of bad battery or temperature faults. Once charging is terminated, the LTC4120 signals end-of-charge via the CHRG pin, and enters a low current sleep mode. An auto-restart feature starts a new charging cycle if the battery voltage drops by 2.2%. Another prominent product available in market is Integrated Wireless Power Li-Ion Charger Receiver, Qi (WPC) Compliant Q51051B from Texas instruments. The bq5105x device is a high-efficiency, Qi-compliant wireless power receiver with an integrated Li-Ion/Li-Pol battery charge controller for portable applications. The bq5105xB devices provide efficient AC-DC power conversion, integrates the digital controller required to comply with Qi v1.1 communication protocol, and provides all necessary control algorithms needed for efficient and safe Li-Ion and Li-Pol battery charging. Together with the bq500212A transmitter-side controller, the bq5105x enables a complete wireless power transfer system for direct battery charger solutions. By using near-field inductive power transfer, the receiver coil embedded in the portable device can pick up the power transmitted by transmitter coil. The AC signal from the receiver coil is then rectified and conditioned to apply power directly to the battery. Global feedback is established from the receiver to the transmitter to stabilize the power transfer process. This feedback is established by using the Qi v1.1 communication protocol. The bq5105xB devices integrate a low-impedance synchronous rectifier, low-dropout regulator (LDO), digital control, charger controller, and accurate voltage and current loops in a single package. The entire power stage (rectifier and LDO) use low-resistance N-MOSFETs (100-mΩ typical Rdson) to ensure high efficiency and low power dissipation. NXP presents NXQ1TXA1 is a state of the art digital control controller for Qi-standard conforming wireless charger base stations. The controller supports type A1 or A10 single coil base stations. The NXQ1TXA1 offers wireless power transfer, WPC 1.1 – Qi low-power standard-compliant communication and safety functions including Foreign Object Detection (FOD), temperature monitoring and more. The controller supports the conventional WPC pinging mode during standby to identify potential receivers. The controller can also work with the trigger function of the NXP NTAG I2C product. This feature enables wake up from a phone its NFC field while having zero power consumption of the charger during standby. The controller also offers a flexible User Interface (UI) with up to two LEDs and one buzzer for feedback and control.
