Method and system for wireless power transfer calibration
View Patent ↗In a WPT system, varying parameters, such as coupling coefficient, may cause the system to fall out of resonance and/or tuning. By monitoring one or more signals within a coil module of the WPT device, this detuning can be detected. Moreover, the WPT system can retune itself by modifying one or more parameters in a transmitting WPT device and/or a receiving WPT device. For example, coil circuits in the transmitting and/or receiving WPT devices can be configured to allow for adjusting of effective capacitance, effective inductance, load resistance, and/or load inductance. In addition, frequency can be modified to permit adjusting power transfer efficiency.
1. A wireless power transfer device, comprising:
a coil module configured to send or receive wireless power transfer signals, the coil module including a coil circuit;
a tuning observer module configured to detect a tuning state of the wireless power transfer device, the tuning state being one of a tuned state or an out-of-tune state; and
a resonance controller module configured to adjust at least one parameter of the coil module in response to the tuning observer module detecting an out-of-tune state in order to provide the tuned state,
wherein the resonance controller module is further configured to determine whether a load of a recipient device is known, and in response to a determination that the load of the recipient device is not known, select the at least one parameter to be an adjustable parameter of the coil circuit, and in response to a determination that the load of the recipient device is known, select the at least one parameter to be a frequency of an input signal input to the coil module.
2. The wireless power transfer device of claim 1 , wherein the coil circuit includes a first resistor, a first capacitor, and a first inductor connected in series.
3. The wireless power transfer device of claim 2 , wherein the tuning observer module is configured to detect the tuning state based on a current passing through the first resistor.
4. The wireless power transfer device of claim 2 , wherein the tuning observer module includes a voltage detector connected at a node between the first capacitor and the first inductor, and
wherein the tuning observer module detects the tuning state based on a voltage detected by the voltage detector.
5. The wireless power transfer device of claim 2 , wherein the tuning observer module includes a second inductor, a second resistor, and a voltage detector connected in parallel.
6. The wireless power transfer device of claim 5 , wherein the second inductor of the tuning observer module is inductively coupled to the first inductor of the coil circuit.
7. The wireless power transfer device of claim 6 , wherein the tuning observer module detects the tuning state based on a voltage detected by the voltage detector.
8. The wireless power transfer device of claim 2 , wherein the resonance controller module includes a tuning capacitor and a control transistor connected in series, the tuning capacitor being connected to a node between the first capacitor and the first inductor of the coil circuit.
9. The wireless power transfer device of claim 8 , wherein the resonance controller module is configured to tune the wireless power transfer device by adjusting a duty cycle of the control transistor.
10. The wireless power transfer device of claim 2 , wherein the resonance controller module includes a tuning inductor serially connected to the first inductor, and a control transistor connected to a node between the first inductor and the tuning inductor.
11. The wireless power transfer device of claim 10 , wherein the resonance controller module is configured to tune the wireless power transfer device by adjusting a duty cycle of the control transistor.
12. A wireless power transfer device, comprising:
a coil module configured to send or receive wireless power transfer signals;
a tuning observer module configured to detect a tuning state of the wireless power transfer device, the tuning state being one of a tuned state or an out-of-tune state; and
a resonance controller module configured to adjust at least one parameter of the coil module in response to the tuning observer module detecting an out-of-tune state in order to provide the tuned state,
wherein the coil module includes a coil circuit having a first resistor, a first capacitor, and a first inductor connected in series, the first inductor including a plurality of windings,
wherein the resonance controller module includes a control transistor connected to the first inductor at a node so as to separate the plurality of windings into a first number of windings and a second number of windings, and
wherein the resonance controller is configured to tune the wireless power transfer device by turning the control transistor on or off.
13. A wireless power transfer device, comprising:
a coil module configured to send wireless power transfer signals;
a system monitor module configured to detect an absence of a calibration-prohibitive event;
a tuning observer module configured to, in response to the detection of the absence of the calibration-prohibitive event, detect a tuning state of the wireless power transfer device, the tuning state being one of a tuned state or an out-of-tune state; and
a resonance controller module configured to, in response to the tuning observer module detecting the out-of-tune state, adjust at least one parameter of the coil module in order to produce the tuned state,
wherein the resonance controller module is further configured to determine whether a load of a recipient device is known, and in response to a determination that the load of the recipient device is not known, select the at least one parameter to be an adjustable parameter of the coil module, and in response to a determination that the load of the recipient device is known, select the at least one parameter to be a frequency of an input signal input to the coil module.
14. The wireless power transfer device of claim 13 ,
wherein the coil module includes a resistor, and
wherein the tuning observer module detects the tuning state of the wireless power transfer device by measuring a current passing through the resistor and comparing the current to a predetermined threshold.
15. The wireless power transfer device of claim 13 ,
wherein the coil module includes a capacitor, and
wherein the tuning observer module detects the tuning state of the wireless power transfer device by measuring a voltage across the capacitor and comparing the voltage to a predetermined threshold.
16. The wireless power transfer device of claim 13 ,
wherein the coil module includes a resistor and a capacitor connected in series, and
wherein the tuning observer module is configured to measure a voltage across the capacitor and a current passing through the resistor.
17. The wireless power transfer device of claim 16 , wherein the tuning observer module detects the tuning state of the wireless power transfer device based on a phase difference between the voltage and the current.
18. The wireless power transfer device of claim 17 , wherein the tuning observer module detects the tuned state when the phase difference is within a predetermined window of zero degrees, and
wherein the tuning observer module detects the out-of-tune state when the phase difference is outside the predetermined window.
19. The wireless power transfer device of claim 13 , wherein the resonance controller module is configured to perform a first calibration technique when the load is known and perform a second calibration technique when the load is unknown,
wherein the first calibration technique includes adjusting the frequency of the input signal and measuring a response in at least one circuit component.
20. The wireless power transfer device of claim 19 , wherein, as part of the first calibration technique, the response is measured by measuring a current passing through a resistor of the resonance controller module.