Voltage converting device and wireless power transmitting device

A wireless power transmitting device, comprising:

• a DC power source configured to generate direct-current voltage;
• an inverter including a first terminal electrically connected to one of a positive-side terminal and a negative-side terminal of the DC power source and including a second terminal electrically connected to another one of the positive-side terminal and the negative-side terminal, the inverter being configured to generate AC power based on the direct-current voltage;
• an AC component detector configured to detect an AC component of current flowing through the first terminal or the second terminal;
• and
• a phase estimator configured to estimate a phase relation between a phase of voltage of the AC power and a phase of current of the AC power based on an amplitude of a specific frequency component contained in a first absolute value signal of the AC component, wherein
• the AC power generated by the inverter is supplied to a loading device, and an impedance of the loading device at a fundamental of a driving frequency of the inverter is smaller than an impedance of the loading device at an odd-order harmonic of the driving frequency, and
• the loading device includes a coil unit including a power transmitting coil and transmits the AC power generated by the inverter to a power receiving coil of a power receiving device through a magnetic coupling.