Power receiver, power transmission system, and power receiving meihod

A power transmission system comprising:

• a power transmitter including a primary-side resonant coil;
• and
• a power receiver that receives power from the power transmitter,
• wherein the power receiver includes:
• a secondary-side resonant coil that includes a resonant coil circuit and receives power from a primary-side resonant coil with magnetic field resonance or electric field resonance generated between the secondary-side resonant coil and the primary-side resonant coil;
• a capacitor inserted into the resonant coil circuit of the secondary-side resonant coil in series;
• a series circuit including a first switch and a second switch and coupled to the capacitor in parallel;
• a first rectifying element coupled to the first switch in parallel and having a first rectification direction;
• a second rectifying element coupled to the second switch in parallel and having a second rectification direction opposite to the first rectification direction;
• a detection circuit that detects a voltage or a current supplied to the secondary-side resonant coil;
• a binarization processing circuit that outputs a rectangular wave obtained by binarizing the voltage or the current detected by the detection circuit;
• a rectangular wave detection circuit that detects a rising or falling timing and a cycle of the rectangular wave output from the binarization processing circuit;
• a reference clock generation circuit that generates a reference clock based on the rising or falling timing and the cycle detected by the rectangular wave detection circuit;
• a control circuit that generates a control clock used to switch on and off of the first switch and the second switch by adjusting a phase or a duty ratio of the reference clock based on the voltage or the current detected by the detection circuit;
• and
• a control clock generation circuit that generates a control clock,
• wherein the rectangular wave detection circuit counts the control clocks from the rising of the rectangular wave to the falling, and
• detects the cycle of the rectangular wave based on an average value of the number of counting obtained over a plurality of the cycles of the rectangular wave.

A power receiving method of a power receiver including:

• a secondary-side resonant coil that includes a resonant coil circuit and receives power from a primary-side resonant coil with magnetic field resonance or electric field resonance generated between the secondary-side resonant coil and the primary-side resonant coil;
• a capacitor inserted into the resonant coil circuit of the secondary-side resonant coil in series;
• a series circuit including a first switch and a second switch and coupled to the capacitor in parallel;
• a first rectifying element coupled to the first switch in parallel and having a first rectification direction;
• a second rectifying element coupled to the second switch in parallel and having a second rectification direction opposite to the first rectification direction;
• and
• a detection circuit that detects a voltage or a current supplied to the secondary-side resonant coil, the power receiving method comprising:
• outputting a rectangular wave obtained by binarizing a voltage or a current detected by the detection circuit;
• detecting a rising or falling timing and a cycle of the rectangular wave;
• generating a reference clock based on the rising or falling timing and the cycle;
• and
• switching on and off of the first switch and the second switch by adjusting a phase or a duty ratio of the reference clock based on the detected voltage or current;
• counting a control clock from the rising of the rectangular wave to the falling;
• and
• detecting the cycle of the rectangular wave based on an average value of the number of counting obtained over a plurality of the cycles of the rectangular wave.