The invention aims to provide a
foreign matter detection method for an LC series topology
wireless charging
system. The method is relatively low in hardware cost, high in reliability and relatively high in precision. The method comprises the following steps that: step 1, in a primary power-on calibration stage, after power-on, the natural resonant frequency f, the quality factor Q and the equivalent
direct current resistance of an LC network of a transmitting end are calculated, and recorded as common parameters; and 2, the output current If of a coupled
current sensor is collected in real time, and the effective value Uf of the input
voltage of an excitation source and the current working frequency f1 of the excitation source during sampling are recorded, the parameters are substituted into a quality factor change rate conversion formula, so that the change rate of the quality factor Q caused by the intervention of
metal foreign matters is to calculated,if the change rate of the current quality factor Q is smaller than a set
metal foreign matter detection judgment threshold value, an alarm is given, and charging is stopped, and if the change rate of the current quality factor Q is within the set
foreign matter detection judgment threshold range, a charging
system is safe, and charging is continued.