Adaptive impedance matching apparatus and method for wireless power transfer

An impedance matching apparatus for energy transmission between a transmitter and a receiver, comprising:

• an impedance adjustment unit comprising a voltage-controlled variable capacitance device;
• a power detector configured to detect a reflection signal which enters a transmitter or receiver when there is no impedance match to measure a magnitude of the reflection signal and convert the reflection signal into a direct current (DC) signal;
• a multiplier configured to multiply the DC signal with a periodic signal;
• an integrator configured to accumulate a first signal output from the multiplier;
• and
• a voltage summer configured to sum a second signal output from the integrator with a reference voltage to calculate a capacitance control voltage to be applied to the voltage-controlled variable capacitance device,
• wherein the impedance adjustment unit is configured to adjust an impedance caused by a change of the capacitance of the voltage-controlled variable capacitance device based on the capacitance control voltage calculated by the voltage summer.