Freescale Semi

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 Freescale


  • Wireless Transmitter System

  • Created: Jun 29, 2015

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Description

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Summary

This wireless project is a power transmission system, it works on the principle of magnetic induction. This Wireless Charging system works as the digital switched mode power supply with the transformer, which is separated into two parts: The transformer primary coil is on the transmitter, working as the transmitter coil, and the transformer secondary coil is on the receiver side as the receiver coil. This system works based on magnetic induction, the better coupling between the transmitter coil and receiver coil gain, the better system efficiency. So the receiver coil should be closely and center aligned with the transmitter coil as possible. After the receiver coil receives the power from the transmitter coil by magnetic field, it regulates the received voltage to power the load, and send its operational information to transmitter according to specific protocol by the communication link. Then the system can achieve the closed-loop control, and power the load stably and wirelessly.


The WCT1000 is a wireless power transmitter controller, it is an intelligent device that can work with Freescale touch sensing technology to detect a mobile device for charging while gaining super low standby power. Once the mobile device is detected, the WCT1000 controls the power transfer by adjusting operation frequency of power stage according to message packets sent by mobile device. The WCT1000 includes digital demodulation module to reduce external components, over-voltage/current/ temperature protection and Foreign Object Detection (FOD) method to protect from overheating by misplaced metallic foreign objects. It also handles any abnormal condition and operational status, and provides comprehensive indicator outputs for robust system design. Capacitive touch sensor is selected in this design, and an additional electrode touch pad is designed to sense the placement of mobile device. When the mobile device is put on the transmitter coil, Touch Sensor IC will detect the capacitance change on the pad, and then trigger an interrupt request signal to wake up WCT1000.


This project eliminates the disadvantages of a wired transmission system like wire corrosion and durability (wear and tear). but the wireless power transmission also has its downsides; lower efficiency, slower charging, and more expensive. Technology is growing fast, electronic devices are being introduced in various scales. Maybe innovations can be made to this project for bigger scale applications like E-car, but as of now, this project can be used on handy mobile devices only.