Wireless data transmission has been around for quite some time, and today’s consumers are increasingly eager to embrace wireless charging capabilities. Technology providers are stepping up to meet this demand, and in this article, Infineon will explore and compare the latest methods and technologies, highlighting the advantages of integrated wireless charging solutions.
Background
Every electronic device needs power, yet most rely on wired connections, often requiring an adapter plugged into a wall outlet. While the term "wireless" is commonly associated with data transmission, radio frequency magnetic fields can also be harnessed to charge devices, offering users greater convenience. Without the need for cables, compatibility issues are minimized, and the safety and reliability of devices are enhanced. Removing physical connectors makes sealing devices easier, which benefits consumers—about one in five smartphones ends up in a liquid mishap each year. One of the greatest perks of wireless charging is eliminating the bulky charging adapter.
As industries move toward universal charging solutions, we might see more public charging stations popping up in places like airports, hotels, event venues, and even fast-food joints and coffee shops.
Challenges for Designers
Most chargers are switch-mode power supplies (SMPS) that require engineers to understand electromagnetism—a skill often considered akin to "magic." Wireless charging operates similarly, except the transformer is split between the charger (now called the "transmitter") and the device being charged.
In wireless charging, the coil and its coupling play a much larger role in overall performance compared to traditional SMPS. Since the coils are independent, their coupling tends to be looser, but with proper design, transmitters and receivers can achieve impressive efficiency. Besides magnetic considerations, designers must address efficiency, packaging, electromagnetic interference (EMI), thermal management, and potential metallic foreign objects like coins or keys.
Wireless Topology and Technology
A typical wireless charging system comprises three main components: an adapter/charger, a transmitter, and a receiver. The adapter converts standard AC power into a regulated DC supply (typically 5-20V) for the transmitter. These adapters can either be separate units connected via wires or integrated into one device.
The transmitter uses a MOSFET-based half-bridge or full-bridge inverter to convert DC to AC, creating an alternating magnetic field. Controlled by a microcontroller and associated MOSFET drivers, this setup provides the flexibility needed for wireless inductive charging.
Two popular topologies for resonant applications are Class D and Class E. While similar in many ways, each has distinct advantages. Class D offers a relatively flat efficiency curve across a wide load range, making it ideal for general-purpose charging stations in public spaces. It's also versatile enough to handle a broad spectrum of power levels.
Class E, on the other hand, is optimized for specific conditions and excels at delivering peak efficiency at certain points. Outside these parameters, however, its efficiency drops significantly. Thus, Class E is better suited for higher-power applications or when charging devices that are nearly depleted. The bill of materials (BOM) cost for Class E is marginally lower than Class D, though the difference isn't substantial.
Infineon provides comprehensive solutions for wireless charging transmitters and SMPS converters, ensuring compatibility and reliability. Their wide selection of wireless charging products empowers engineers to build systems with confidence.
At the heart of the transmitter design lies the microcontroller, which handles system control and intelligence. Infineon’s XMC microcontroller family offers numerous options, with models like the XMC1100, 1402, and XMC4108 being particularly well-suited for Class D and Class E topologies.
The EiceDRIVER gate driver converts microcontroller signals into drive signals for MOSFETs. For Class D designs, the new 2EDL71 is recommended, while the established 1EDN remains the go-to choice for Class E applications.
Infineon offers a vast array of MOSFETs, differentiated by package size and critical parameters such as RDS(ON) and Qg. They boast industry-leading figures of merit (FoM), with voltage ratings ranging from 30V to 250V. This versatility enables designers to craft wireless chargers for various power levels using the same circuitry. Infineon’s OpTIMOS MOSFETs excel in Class D or Class E inverters (including synchronous rectification), while the CE and P7 versions of CoolMOS devices are used in AC-DC adapters.
For power adapters, Infineon provides a range of flyback controllers along with CoolSETs, which integrate controllers and power units.
To support these component solutions, Infineon’s newly developed Class D power amplifier transmitter test board helps designers quickly develop efficient and compact solutions. This board lets designers evaluate the performance of Infineon MOSFETs in Class D power amplifiers. It includes two half-bridges using an 80V 2x2 Infineon MOSFET (IRL80HS120) and associated drivers, allowing operation in both single-ended and differential configurations.
An onboard oscillator ensures precise 6.78 MHz operation and provides a pin to set the switching frequency externally via a waveform generator. All necessary components are included to design a zero-voltage-switching (ZVS) power solution for maximum efficiency. A linear regulator supplies a stable voltage for board logic.
A second BNC connector connects to an external transmit coil for radio energy transmission. Pairing this with a wireless charging receiver completes a full design.
Summary
Wireless charging mirrors the convenience of wireless data transmission. As standards and methods converge, increased interoperability between chargers and devices will offer users unprecedented convenience. Continued innovation will elevate wireless charging to new heights, enabling more devices to be charged without wires.
As a leading provider, Infineon offers a full suite of products for AC adapters and transmitters, each characterized by superior performance, including low switching/conduction losses, minimal parasitics, and high FoM values. This enables designers to build wireless charging solutions leveraging proven silicon MOSFET technology. Infineon’s deep expertise in power semiconductors and microcontrollers solidifies its position as a technology and quality leader.
Test boards that expedite product evaluation and development complement Infineon’s broad product portfolio, offering comprehensive coverage for wireless charging designs. Infineon delivers advanced products and valuable ecosystem support to current and future wireless charging solution designers.
Author:
Stephan Schächer, Head of Technology and Systems Marketing, Infineon Technologies DCDC
Milko Paolucci, Senior Application Engineer, Infineon Technologies
Diesel Light Tower
A diesel light tower is a portable lighting system that is powered by a diesel engine. It is commonly used in construction sites, outdoor events, and other areas where temporary lighting is required.
The diesel engine powers a generator, which in turn provides electricity to the light fixtures mounted on top of the tower. These light fixtures are typically high-intensity discharge (HID) lamps, such as metal halide or high-pressure sodium lamps, which produce a bright and efficient light output.
Diesel light towers are designed to be easily transportable and can be quickly set up and operated. They are often equipped with features such as telescoping masts, adjustable light angles, and automatic timers for convenient use.
The main advantage of diesel light towers is their ability to provide a large amount of bright light over a wide area. This makes them ideal for illuminating construction sites, outdoor events, and emergency situations where visibility is crucial. In addition to providing illumination, some diesel light towers also come with auxiliary power outlets, allowing them to be used as a source of electricity for other equipment or tools on-site.
Overall, diesel light towers are a reliable and efficient solution for temporary lighting needs in various applications.
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Grandwatt Electric Corp. , https://www.grandwattelectric.com