FREE-RESONANCE ANALOG PING FOR WIRELESS POWER TRANSMISSION

• US 20160268842A1
• Filed: 09/27/2015
• Published: 09/15/2016
• Est. Priority Date: 03/13/2015
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Wang, Li, Wang, Dechang, Shi, Changhao
• Granted Patent: US 10,079,509 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004

Abstract

A wireless transmitter wirelessly charges/powers a wireless receiver. The transmitter performs an analog ping to tentatively detect a device. During an energizing phase of the analog ping, the transmitter applies power pulses to a resonant circuit within the transmitter, where, after application of the power pulses, the resonant circuit enters a free-resonance state of a resonating phase of the analog ping that follows the energizing phase. During the resonating phase, while the resonant circuit is in the free-resonance state, the transmitter samples voltage within the resonant circuit to generate one or more voltage-level samples. The transmitter processes the voltage-level samples to tentatively detect the device. If a device is tentatively detected then the transmitter performs a digital ping to definitively determine whether the device is present. If definitively detected then the transmitter wirelessly charges/powers the wireless receiver.

Claims

1. A wireless transmitter for charging or powering a wireless receiver, the wireless transmitter comprising:

a resonant circuit; and

a controller, wherein;

the controller performs an analog ping to tentatively determine whether the wireless receiver is present, wherein;

(a) during an energizing phase of the analog ping, the controller causes one or more power pulses to be applied to the resonant circuit, wherein, after application of the pulses, the resonant circuit enters a free-resonance state of a resonating phase of the analog ping that follows the energizing phase;

(b) during the resonating phase, while the resonant circuit is in the free-resonance state, the controller causes voltage within the resonant circuit to be sampled one or more times to generate one or more voltage-level samples; and

(c) the controller processes the voltage-level samples to tentatively determine whether the wireless receiver is present;

(d) if the controller tentatively determines that the wireless receiver is present, then the controller causes a digital ping to be performed to definitively determine whether the wireless receiver is present; and

(e) if the controller definitively determines that the wireless receiver is present, then the controller causes the wireless transmitter to wirelessly charge or power the wireless receiver.

2. The wireless transmitter of claim 1, wherein the resonant circuit is a tank circuit comprising:

an inductor; and

a capacitor connected in series with the inductor,

wherein when the wireless receiver is present, the inductor functions as a primary coil of a transformer whose secondary coil is part of the wireless receiver, such that the presence of the secondary coil alters at least one of resonant amplitude and resonant frequency of the tank circuit.

3. The wireless transmitter of claim 2, further comprising:

a plurality of switches configurable to selectively (i) energize the tank circuit or (ii) configure the tank circuit for free-resonance, wherein, at the end of the energizing phase and throughout the resonating phase, the switches are configured such that the tank circuit is configured for free-resonance.

4. The wireless transmitter of claim 3, wherein:

during the resonating phase, no power pulses are applied to the resonant circuit;

the controller includes a comparator for comparing a present measure based on the one or more voltage-level samples to a previous measure based on one or more voltage-level samples from a previous analog ping to tentatively determine whether the wireless receiver is present, wherein the present measure is one of an amplitude measure or a frequency measure;

the controller tentatively determines whether the wireless receiver is present by determining whether resonant amplitude or frequency within the resonant circuit has changed by more than a predetermined amount;

if the present measure is the amplitude measure, then the controller determines the resonant amplitude with as few as one voltage-level sample; and

if the present measure is the frequency measure, then the controller determines the resonant frequency with as few as two voltage-level samples.

5. A method for wirelessly charging a wireless receiver by a wireless transmitter, comprising:

performing an analog ping, by the wireless transmitter, to tentatively determine whether the wireless receiver is present, wherein;

(a) during an energizing phase of the analog ping, the wireless transmitter applies one or more power pulses to a resonant circuit within the wireless transmitter, wherein, after application of the one or more power pulses, the resonant circuit enters a free-resonance state of a resonating phase of the analog ping that follows the energizing phase;

(b) during the resonating phase, while the resonant circuit is in the free-resonance state, the wireless transmitter samples voltage within the resonant circuit one or more times to generate one or more voltage-level samples; and

(c) the wireless transmitter processes the one or more voltage-level samples to tentatively determine whether the wireless receiver is present;

(d) if the wireless transmitter tentatively determines that the wireless receiver is present, then the wireless transmitter performs a digital ping to definitively determine whether the wireless receiver is present; and

(e) if the wireless transmitter definitively determines that the wireless receiver is present, then the wireless transmitter wirelessly charges or powers the wireless receiver.

6. The method of claim 5, wherein, during the resonating phase, no power pulses are applied to the resonant circuit.

7. The method of claim 5, wherein step (c) comprises the wireless transmitter comparing a present measure based on the one or more voltage-level samples to a previous measure based on one or more voltage-level samples from a previous analog ping to tentatively determine whether the wireless receiver is present.

8. The method of claim 7, wherein the present measure is an amplitude measure.

9. The method of claim 7, wherein the present measure is a frequency measure.

10. The method of claim 5, wherein the controller tentatively determines whether the wireless receiver is present by determining whether the resonant amplitude within the resonant circuit has changed by more than a predetermined amount.

11. The method of claim 10, wherein the wireless transmitter determines the resonant amplitude by summing or averaging two or more voltage-level samples.

12. The method of claim 5, wherein the wireless transmitter tentatively determines whether the wireless receiver is present by determining whether resonant frequency within the resonant circuit has changed by more than a predetermined amount.

13. The method of claim 12, wherein the wireless transmitter determines the resonant frequency using one or more voltage-level samples and by frequency transforming the one or more multiple voltage-level samples.

14. The method of claim 5, wherein the wireless transmitter tentatively determines whether the wireless receiver is present by determining whether both of resonant amplitude and resonant frequency within the resonant circuit have changed by more than respective predetermined amounts.

15. The method of claim 5, wherein the wireless transmitter tentatively determines whether the wireless receiver is present by determining whether either of resonant amplitude and resonant frequency within the resonant circuit has changed sufficiently.

16. The method of claim 5, wherein the resonant circuit is a tank circuit comprising:

an inductor; and

a capacitor connected in series with the inductor.

17. The method of claim 16, wherein the wireless transmitter further comprises a plurality of switches configurable to selectively (i) energize the tank circuit or (ii) configure the tank circuit for free-resonance, wherein, at MU15234CH the end of the energizing phase and throughout the resonating phase, the switches are configured such that the tank circuit is configured for free-resonance.

18. The method of claim 16, wherein, when the wireless receiver is present, the inductor functions as a primary coil of a transformer whose secondary coil is part of the wireless receiver, such that, the presence of the secondary coil alters at least one of a resonant amplitude and a resonant frequency of the tank circuit.

19. The method of claim 5, wherein:

during the resonating phase, no power pulses are applied to the resonant circuit;

step (c) comprises the wireless transmitter comparing a present measure based on the one or more voltage-level samples to a previous measure based on one or more voltage-level samples from a previous analog ping to tentatively determine whether the wireless receiver is present;

the present measure is one of an amplitude measure or a frequency measure;

the wireless transmitter tentatively determines whether the wireless receiver is present by determining whether resonant amplitude or frequency within the resonant circuit has changed by more than a predetermined amount;

if the present measure is the amplitude measure, then the wireless transmitter determines the resonant amplitude with as few as one voltage-level sample;

if the present measure is the frequency measure, then the wireless transmitter determines the resonant frequency with as few as two voltage-level samples;

the resonant circuit is a tank circuit comprising;

an inductor; and

a capacitor connected in series with the inductor;

the wireless transmitter further comprises a plurality of switches configurable to selectively (i) energize the tank circuit or (ii) configure the tank circuit for free-resonance, wherein, at the end of the energizing phase and throughout the resonating phase, the switches are configured such that the tank circuit is configured for free-resonance; and

when the wireless receiver is present, the inductor functions as a primary coil of a transformer whose secondary coil is part of the wireless receiver, such that the presence of the secondary coil alters at least one of resonant amplitude and resonant frequency of the tank circuit.