The Ultimate Guide to Wireless Charging

The Ultimate Guide to Wireless Charging

The Ultimate Guide to Wireless Charging

What is the Wireless Charging?

Wireless charging is to transfer power through non-conductive means (usually using magnetic field as a bridge for power transfer).

Wireless phone charger
The working of wirelss charging
What Frequency change can change the output power?
System Overview
  • Base Station

βˆ’Contains one, or more transmitters

βˆ’Transmitter provides power to receiver

  • Mobile Device

βˆ’Contains a receiver that provides power to a load (e.g. a battery)

βˆ’Receiver provides control information to transmitter

The working of wireless charging
System Overview (Power Conversion)
  • Power Conversion Unit converts electrical power to wireless power signal
  • Power Pickup Unit converts wireless power signal to electrical power
wireless charging Working principle
System Overview (Control)
  • Receiver controls the power to the output load

βˆ’ To the need of the mobile device (required power)

βˆ’ To the desired operation point (e.g. output current, voltage)

  • Transmitter adapts power transfer

βˆ’ To the need of the receiver (required power)

βˆ’ To the desired operation point (e.g. primary coil current)

wireless charging control working principle
System Overview (Communication)
  • Receiver sends messages

βˆ’To provide control and device information to the transmitter by load modulation on the power signal

βˆ’To receive the device information from the transmitter by de-modulation (to be added in Qi v1.2)

  • Transmitter receives messages

βˆ’To receive control and device information from the receiver by de-modulation

βˆ’To provide device information to the receiver by frequency modulation on the power signal (to be added in v1.2)

Wireless charging communction working
Power Pick Up (Receiver)
  • Secondary coil (Ls)
  • Serial resonance capacitor (Cs ) for efficient power transfer
  • Parallel resonance capacitor (Cd ) for detection purposes
  • Rectifier: full bridge (diode, or switched) + capacitor
  • Output switch for (dis-)connecting the load
Wireless charging communction working
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