Resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies

Patent metadata

Field	Value
Publication number	US-10622841-B2
Application number	US-201815878778-A
Country	US
Kind code	B2
Filing date	Jan 24, 2018
Priority date	Aug 21, 2017
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

A resonant magnetic coupling wireless power transfer system with calibration capabilities of the resonant frequencies of its power transmitter(s) and power receiver(s) is disclosed. The system detects the peak voltages of the coil inductors or the resonant capacitors and tunes the resonant capacitors until the detected peak voltages reach their maximal values given proper setup conditions, so as to calibrate the inductor-capacitor (LC) resonance frequencies of the power transmitter(s) and the power receiver(s) in the resonant magnetic coupling wireless power transfer system to achieve the highest power transferred to the load and a high PTE.

First claim

What is claimed is:

1. A resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies, comprising
at least one power receiver each at least including a secondary coil and a resonant load circuit; and
at least one power transmitter transmitting an alternating-current power using a carrier wave to said at least one power receiver, and said power transmitter at least including a power amplifier and an inductor-capacitor (LC) resonator driven by said power amplifier, wherein said LC resonator equivalently includes at least a first resonant capacitor and a primary coil connected in series; a primary-side-observation (PSO) voltage is generated by the primary coil or generated across the first resonant capacitor; during calibrating said first resonant capacitor, said first resonant capacitor is tuned until said PSO voltage's peak voltage reaches its maximal value, and thus said first resonant capacitor achieves its optimal capacitance value, wherein a calibration process of said first resonant capacitor includes steps:
(S 1 ) setting said first resonant capacitor to an initial value, detecting a peak voltage of said PSO voltage, and storing said peak voltage as a first PSO peak voltage;
(S 2 ) adding a predetermined first-resonant-capacitor-incremental (FRCI) step value to the capacitance of said first resonant capacitor;
(S 3 ) detecting said peak voltage of said PSO voltage again, and storing said detected PSO voltage's peak voltage as a second PSO peak voltage;
(S 4 ) determining whether an absolute value of the difference of said first PSO peak voltage and said second PSO peak voltage is within a predetermined PSO tolerable range; if yes, stopping said calibration process, and preserving the last value of said first resonant capacitor as a calibration result if no, undertaking the next step;
(S 5 ) if said second PSO peak voltage is greater than said first PSO peak voltage, adding another predetermined FRCI step value to said first resonant capacitor; if said second PSO peak voltage is smaller than said first PSO peak voltage, subtracting another predetermined FRCI step value from said first resonant capacitor; and
(S 6 ) replacing the value of said first PSO peak voltage with the value of said second PSO peak voltage, returning to Step (S 3 ), and undertaking said steps again in sequence.

2. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 , wherein said resonant load circuit of said power receiver is selected from:
a series resonant load circuit equivalently including at least a second resonant capacitor and a resistive load connected in series, wherein said secondary coil generates a secondary-side-observation (SSO) voltage; said primary coil and said secondary coil have a coupling coefficient there between; and
a shunt resonant load circuit equivalently including at least a second resonant capacitor and a resistive load connected in parallel, wherein said secondary coil generates said SSO voltage; said primary coil and said secondary coil have a coupling coefficient there between.

3. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 , wherein in Step (S 5 ), said another predetermined FRCI step value is dynamically adjusted according to said difference of said first PSO peak voltage and said second PSO peak voltage and has the same sign as said predetermined FRCI step value in Step (S 2 ).

4. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 , wherein said first resonant capacitor is a digitally-controlled variable capacitor or a voltage-controlled variable capacitor.

5. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 , wherein while said first resonant capacitor is being calibrated, said secondary coil is in a short-circuit state or an open-circuit state.

6. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 , wherein while said first resonant capacitor is being calibrated, said power receiver is removed beforehand.

7. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 1 further comprising a peak voltage detector electrically connected with said primary coil or said first resonant capacitor and used to detect said peak voltage of said PSO voltage.

8. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 7 further comprising a primary-side controller electrically connected with said peak voltage detector, receiving and storing said peak voltages of said PSO voltage, and tuning said first resonant capacitor according to said calibration process of said first resonant capacitor.

9. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 2 , wherein said second resonant capacitor of said power receiver is calibrated to achieve a maximal PTE; while said second resonant capacitor is being calibrated, said first resonant capacitor is set beforehand to have a value obtained by said calibration process of said first resonant capacitor under a condition that said secondary coil is in an open-circuit or a short-circuit state or a condition that said power receiver is removed, and then said second resonant capacitor is tuned until said SSO voltage's peak voltage reaches its maximal value, and thus said second resonant capacitor achieves its optimal value.

10. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 9 , wherein said second resonant capacitor is a digitally-controlled variable capacitor or a voltage-controlled variable capacitor.

11. The resonant magnetic coupling wireless power transfer system with calibration capabilities of its inductor-capacitor resonant frequencies according to claim 9 , wherein a calibration process of said second resonant capacitor includes steps:
(S 1 ) setting said second resonant capacitor to an initial value, detecting a peak voltage of said SSO voltage, and storing said peak voltage as a first SSO peak voltage;
(S 2 ) adding a predetermined second-resonant-capacitor-incremental (SRCI) step value to the capacitance of said second resonant capacitor;
(S 3 ) detecting said SSO voltage's peak voltage again, and storing said detected SSO voltage's peak voltage as a second SSO peak voltage;
(S 4 ) determining whether an absolute value of the difference of said first SSO peak voltage and said second SSO peak voltage is within a predetermined SSO tolerable range; if yes, stopping said calibration process, and preserving the last value of said second resonant capacitor as a calibration result of said second resonant capacitor; if no, undertaking the next step;
(S 5 ) if said second SSO peak voltage is greater than said first SSO peak voltage, adding another predetermined SRCI step value to the capacitance of said second resonant capacitor; if said second SSO peak voltage is smaller than said first SSO peak voltage, subtracting another predetermined SRC

Assignees

• Univ National Chiao Tung

Inventors

• Hong Hao-Chiao

Classifications

• H02J50/12 Primary

  of the resonant type · CPC title

• H03J3/24

  of more than one resonant circuit simultaneously, the circuits being tuned to substantially the same frequency, e.g. for single-knob tuning · CPC title

• H03J7/02

  Automatic frequency control (H03J7/18 takes precedence) · CPC title