Control method of a minimum power input

A control method of a minimum power input, applicable to a wireless power transfer system including a power transmission unit and at least one power receiving unit, wherein the power transmission unit is electrically connected with a control voltage signal and an input voltage signal and accordingly generates the minimum power input, and wherein the power transmission unit transmits the minimum power input wirelessly to the at least one power receiving unit for receiving, the control method comprising:

• measuring a distance, which is between the power transmission unit and the at least one power receiving unit and obtaining the distance;
• measuring the input voltage signal and determining the input voltage signal based on the distance and a number of the at least one power receiving unit;
• computing a power input curve based on the input voltage signal and determining a minimum value of the power input curve, wherein the minimum value correlates with a specific resonant frequency and a specific duty ratio of the control voltage signal;
• measuring the specific duty ratio and the specific resonant frequency of the control voltage signal and retrieving the specific duty ratio and the specific resonant frequency sequentially which are corresponding to the minimum value;
• and
• inputting the control voltage signal having the specific duty ratio and the specific resonant frequency into the power transmission unit, such that the power transmission unit accordingly generates the minimum power input which is received sufficiently by the at least one power receiving unit, wherein the power transmission unit comprises a gate driving circuit, a pair of tuning resistor, a charge pump reservoir, a switching component and an amplifier circuit, the gate driving circuit receives the control voltage signal, the pair of tuning resistor is connected between the gate driving circuit and the charge pump reservoir, the switching component is connected with the charge pump reservoir and the amplifier circuit, and wherein when the gate driving circuit receives the control voltage signal having the specific duty ratio and the specific resonant frequency, and the amplifier circuit receives the input voltage signal, the minimum power input is accordingly generated at an output terminal of the amplifier circuit through turning on and turning off of the switching component.