1. Electromagnetic induction:
Principle: This is the most common and widely used wireless charging method, which is based on the electromagnetic induction phenomenon. The electromagnetic induction phenomenon was discovered by Michael Faraday in 1831, that is, when the magnetic flux changes, an induced electromotive force will be generated in a closed circuit.
Working process: The transmitter of the wireless charger has a built-in coil. When current passes through this coil, a constantly changing magnetic field is generated. The receiving end is inside the electronic device and also has a coil. When an electronic device that supports wireless charging is placed near the transmitter, the receiving coil is in the magnetic field generated by the transmitter. Due to electromagnetic induction, an induced electromotive force will be generated in the receiving coil, and then an induced current will be generated. After rectification and other processing, the generated induced current can charge the battery of the electronic device. For example, mobile phone wireless charging is this method.
2. Electromagnetic resonance:
Principle: Resonance is an efficient energy transmission method, and electromagnetic resonance wireless charging uses this principle. It makes the coils in the energy sending device and the receiving device have the same vibration frequency. At a specific frequency, the coils at the sending end and the receiving end will resonate with the magnetic field, thereby achieving efficient energy transmission.
Working process: The transmitter is connected to the power supply to generate an oscillating magnetic field. When the frequency of the magnetic field is the same as the natural vibration frequency of the coil at the receiving end, the receiving end resonates, receives the magnetic field energy and converts it into electrical energy, and charges the device after processing. This method can theoretically transmit energy with a higher power and a relatively long transmission distance, but it has higher requirements on the size and frequency of the coil.
3. Radio wave method:
Principle basis: This method mainly uses microwaves for power transmission. Microwaves refer to electromagnetic waves with a frequency between 30MHz and 300GHz, which have a strong energy transmission capacity.
Working process: An electromagnetic wave generator is placed at the power supply, and energy is transmitted to the receiving antenna in the form of electromagnetic waves through the transmitting antenna. The micro receiving device at the receiving end is embedded in the charged electronic device to capture the electromagnetic waves emitted by the transmitter, and then the electromagnetic wave signal is converted back into electrical energy for the device to use. However, due to the huge spatial path loss of microwave radiation transmission, the transmission power of this charging technology is relatively small and is only suitable for electronic devices with very low power.
