Wireless power transmission device and wireless power transmission system

A wireless power transmission device for wirelessly transmitting power to at least one wireless power reception device using a magnetic field, the wireless power transmission device comprising:

• a wireless power transmission circuit part comprising:
• a rectifier configured to convert external input power into direct-current (DC) power;
• and
• a voltage amplifier configured to convert a voltage of the DC power received from the rectifier;
• a power transmitter configured to generate the magnetic field from the DC power, the voltage of which is converted by the wireless power transmission circuit part;
• an impedance matching part configured to match impedances of the power transmitter and the wireless power transmission circuit part, the impedance matching part being arranged between the power transmitter and the wireless power transmission circuit part;
• and
• a controller configured to control the impedance matching part,
• wherein the impedance matching part comprises a variable inductor or a variable capacitor, and
• the controller controls an impedance of the impedance matching part while maintaining a predetermined resonance frequency, according to a change in a power transmission condition based on information received from the wireless power reception device by the wireless power transmission device.