At present, a wireless charging device comprises a power source, an electronic switch, and a transmitting coil electrically connected in sequence. Switch on/off of the electronic switch is controlled by a Pulse Width Modulation (PWM) controller. The transmitting coil is connected to the power source through the electronic switch. A field-effect switching tube with high power usually serves as the electronic switch mentioned above. Because a high heat value can be generated on the electronic switch due to a dynamic resistance, heat sinks with large area are needed to regulate the work of the electronic switch, which increases the cost and is especially adverse to product with low cost and small size. According to a traditional method of preparing a wireless charging device for electronic cigarette, heat sinks are required. The heat sink has an effective heat release area of more than 3*3 cm2, and the cost is about 2 RMB. Furthermore, the current transmitting coil doesn't transmit and the receiving efficiency is rather low when the electronic switch is off, both causing extra heat generation of the field-effect switching tube.
USPTO Backgrounds
USPTO Backgrounds