Qi coils are the core components used in wireless power transfer (WPT) systems based on the Qi standard, developed by the Wireless Power Consortium (WPC). The Qi standard primarily supports inductive charging, though newer versions include resonant charging over greater distances. Although the majority of the applications are based upon mobile phones there are many other uses for this technology. Lets look at the key elements and then some of the possible uses elsewhere.
Overview of the Key Components & Operating Principles:
- Transmitter Coil (TX):
- Located in the charging pad.
- Converts electrical energy into an oscillating magnetic field using alternating current (AC).
- Typically operates at 110–205 kHz.
- Receiver Coil (RX):
- Embedded in the device to be charged.
- Captures the magnetic field and converts it back into electrical energy via electromagnetic induction.
- Rectifier and power management IC regulate the output.
- Control and Communication:
- Uses in-band communication (backscatter modulation) for negotiation between TX and RX (e.g., power needs, foreign object detection, alignment).
- Supports Foreign Object Detection (FOD) for safety.
- Power Output:
- Qi v1.3 supports up to 15W (fast charging).
- Qi2 (based on Apple’s MagSafe) enhances efficiency, alignment via magnetic positioning, and supports higher power levels and resonant charging.
Non-Mobile Phone Applications of Qi Coils
Beyond smartphones, Qi coils are used in various sectors where cordless power, sealed enclosures, or ease of use are critical. Some of these applications are as follows and also some of the advantages wireless charging offers.
- Medical Devices
- Hearing aids, implants, insulin pumps, and wearable monitors.
- Qi charging eliminates infection risk from open charging ports.
- Wearables and Hearables
- Smartwatches, fitness bands, AR/VR headsets.
- Enables waterproofing and compact design.
- Automotive Applications
- Qi pads integrated into car dashboards or armrests.
- Also used for charging key fobs, IoT sensors, or connected vehicle modules.
- Home Automation / Smart Home Devices
- Wireless power for smart locks, thermostats, doorbell cameras, etc.
- Simplifies installation and enhances weatherproofing.
- Office and Commercial Equipment
- Conference tables with embedded Qi pads.
- Wireless charging for presentation remotes, tablets, styluses, and POS terminals.
- Industrial / Harsh Environments
- Powering sensors, actuators, or controllers in sealed or rotating systems (e.g., a robot arm joint or pump).
- Avoids contact corrosion and wear.
- Battery Charging for Small Devices
- Flashlights, hearing protection headsets, GPS trackers, cameras.
- Qi-based wireless docks simplify multi-device charging.
- Toys and Education
- Interactive toys and STEM kits.
- Safer and easier for children with no exposed contacts.
Summary
Qi coils offer a compact, standardized, and safe wireless power solution. While they are best known for mobile phone charging, their sealed design, ease of integration, and efficiency make them ideal for medical, automotive, industrial, and wearable applications where traditional wired power is impractical or undesirable.
Our partner EEMPL offers the industry’s widest range of WPC Qi approved low power & medium power coils for Tx & Rx wireless applications.
We specialize in custom designs, shapes, additional features (FOD’s, NTC’s, connectors etc), small, thin, safe & reliable
We also offer automotive grade (AEC-Q200) coils for phone & EV battery charging from the pioneers of wireless charging coils (IATF16949 approved)
Let us know if you’d like schematics or details on custom Qi coil integration.
