Wireless charging circuit, wireless charging method, device, and system
View Patent ↗The wireless charging circuit includes an oscillation circuit and a monitoring circuit that are sequentially connected. The oscillation circuit includes an excitation voltage source, a full-bridge circuit, and an LC series circuit that are connected in series. When damped oscillation occurs in the LC series circuit, the LC series circuit outputs a resonant voltage signal during damped oscillation to the monitoring circuit. The monitoring circuit includes a comparison module and a processing module. The comparison module is configured to receive the resonant voltage signal and convert the resonant voltage signal into a digital square wave signal. The processing module is configured to receive the digital square wave signal, obtain a quantity of peaks, a quantity of troughs, or a sum of the quantity of peaks and the quantity of troughs and that is in a resonant voltage attenuation waveform, determine a quality factor Q.
1 . A wireless charging circuit, comprising
an oscillation circuit, wherein the oscillation circuit comprises:
an excitation voltage source,
a half-bridge circuit, and
an LC series circuit that are connected in series, wherein the LC series circuit comprises
an inductor and a resonance capacitor that are connected in series, wherein:
a first terminal of the LC series circuit is connected to a phase midpoint of the half-bridge circuit,
a second terminal of the LC series circuit is connected to the ground, and the excitation voltage source is configured to provide a stable voltage for the LC series circuit; and
a monitoring circuit, wherein a phase midpoint of the LC series circuit is connected to the monitoring circuit configured to output a resonant voltage signal during damped oscillation to the monitoring circuit, and the monitoring circuit comprises:
a voltage biasing module connected to the oscillation circuit and configured to:
receive the resonant voltage signal output by the oscillation circuit,
bias the resonant voltage signal, and
transmit a biased resonant voltage signal to the comparison module;
a comparison module configured to configured to:
receive the biased resonant voltage signal and
convert the biased resonant voltage signal into a digital square wave signal;
and
a processing module, wherein the comparison module and the processing module are sequentially connected, and
the processing module is configured to:
receive the digital square wave signal,
obtain a resonant voltage attenuation waveform during damped oscillation,
obtain a first parameter that meets a first preset condition in the resonant voltage attenuation waveform,
determine a quality factor Q based on the first parameter, and
monitor a foreign object based on the quality factor Q to obtain a monitoring result, wherein the first parameter comprises a quantity of peaks, a quantity of troughs, or a sum of the quantity of peaks and the quantity of troughs, and the quality factor Q represents a ratio of power stored in the oscillation circuit to a power loss in each cycle.
2 . The wireless charging circuit according to claim 1 , wherein the first preset condition is that in each oscillation cycle, a resonant voltage generated during damped oscillation is greater than a reference voltage; and
when a voltage of the phase midpoint of the LC series circuit to ground reaches an amplitude voltage of the excitation voltage source, the damped oscillation occurs in the oscillation circuit to generate the resonant voltage.
3 . The wireless charging circuit according to claim 1 , wherein
the first parameter comprises the sum of the quantity of peaks and the quantity of troughs, and the sum is the sum of the quantity of peaks that meets the first preset condition and the quantity of troughs that meets the first preset condition.
4 . The wireless charging circuit according to claim 1 , wherein the processing module is further configured to determine, based on the first parameter, the quality factor Q:
Q
=
n
·
π
m
·
ln
(
❘
"\[LeftBracketingBar]"
U
1
/
U
2
❘
"\[RightBracketingBar]"
)
,
wherein
m and n are both positive integers, m≥1, and U1 and U2 are any peak voltage or any trough voltage in the resonant voltage attenuation waveform.
5 . The wireless charging circuit according to claim 4 , wherein when m=2, the quality factor Q is:
Q
=
n
·
π
2
·
ln
(
❘
"\[LeftBracketingBar]"
U
1
/
U
2
❘
"\[RightBracketingBar]"
)
,
wherein
n is the sum of the quantity of peaks and the quantity of troughs.
6 . A device, wherein the device is a transmit device or a receive device, and the transmit device or the receive device comprises the wireless charging circuit according to claim 1 .
7 . A system comprising:
a transmit device and
a receive device, wherein transmit device comprises the wireless charging circuit according to claim 1 , and the receive device is a to-be-charged device.
8 . A wireless charging circuit, comprising
an oscillation circuit comprising:
an excitation voltage source,
a half-bridge circuit that comprises a fifth switching transistor Q 5 and a sixth switching transistor Q 6 that are connected in series, and
an LC series circuit that comprises an inductor and a resonance capacitor that are connected in series, wherein:
a first terminal of the LC series circuit is connected to a phase midpoint of the half-bridge circuit,
a second terminal of the LC series circuit is connected to the ground,
a phase midpoint of the LC series circuit is connected to the monitoring circuit and is configured to output a resonant voltage signal during damped oscillation to the monitoring circuit;
the excitation voltage source is configured to provide a stable voltage for the LC series circuit, and
the excitation voltage source, the half-bridge circuit, and the LC series circuit connected in series; and
a monitoring circuit, comprising:
a voltage biasing module, wherein the voltage biasing module is connected to the oscillation circuit and is configured to:
receive the resonant voltage signal output by the oscillation circuit,
bias the resonant voltage signal, and
transmit a biased resonant voltage signal to the comparison module;
a comparison module configured to:
receive the biased resonant voltage signal,
convert the biased resonant voltage signal into a digital square wave signal, and
output the digital square wave signal to the processing module, and
a processing module, wherein the voltage biasing module, the comparison module, and the processing module are sequentially connected, and the processing module is configured to:
receive the digital square wave signal,
obtain a resonant voltage attenuation waveform during damped oscillation,
obtain a second parameter that meets a second preset condition in the resonant voltage attenuation waveform,
determine a quality factor Q based on the second parameter, and
monitor a foreign object based on the quality factor Q to obtain a monitoring result, wherein the second parameter comprises a sum of a quantity of peaks and a quantity of troughs, and the quality factor Q represents a ratio of power stored in the oscillation circuit to a power loss in each cycle.
9 . The wireless charging circuit according to claim 8 , wherein the second preset condition is:
Uc+V ref 0 >V ref 1 or Uc+V ref 0 <V ref 2 , wherein
Uc is a resonant voltage generated during damped oscillation, V ref 0 is a bias voltage, Uc+V ref 0 is a resonant voltage biased by the voltage biasing module, V ref 1 is a first reference voltage, and V ref 2 is a second reference voltage; and
when a voltage of the phase midpoint of the LC series circuit to ground reaches an amplitude voltage of the excitation voltage source Us, the damped oscillation occurs in the oscillation circuit to generate the resonant voltage.
10 . The wireless charging circuit according to claim 9 , wherein the sum of the quantity of peaks and the quantity of troughs is the sum of the quantity of peaks and the quantity of troughs that meets the second preset condition and that is determined, based on the digital square wave signal output by the comparison module, by the processing module when the fifth switching transistor Q 5 is changed from on to off and the sixth switching transistor Q 6 is changed from off to on.
11 . The wireless charging circuit according to claim 8 , wherein an input terminal of the comparison module is connected to an output terminal of the voltage biasing module, and an output terminal is connected to the processing module; the comparison module comprises a first comparator and a second comparator; the first comparator and the second comparator each comprise a first input terminal, a second input terminal, and an output terminal; the first input terminal of the first comparator is connected to a first voltage source, and is configured to obtain the first reference voltage provided by the first voltage source; the second input terminal of the first comparator and the first input terminal of the second comparator are connected to each other to be used as the input terminal of the comparison module; the second input terminal of the second comparator is connected to a second voltage source, and is configured to obtain the second reference voltage provided by the second voltage source; and the output terminal of the first comparator and the output terminal of the second comparator are connected to each other.
12 . The wireless charging circuit according to claim 8 , wherein the processing module is further configured to determine, based on the second parameter, the quality factor Q:
Q
=
n
·
π
m
·
ln
(
❘
"\[LeftBracketingBar]"
U
0
Δ
V
❘
"\[RightBracketingBar]"
)
,
wherein
n and m are both positive integers, m≥1, U 0 is a voltage amplitude of the excitation voltage source, ΔV is a voltage difference between a bias voltage and a reference voltage, and the reference voltage is the first reference voltage or the second reference voltage.
13 . The wireless charging circuit according to claim 12 , wherein when m=2, the quality factor Q is:
Q
=
n
·
π
2
·
ln
(
❘
"\[LeftBracketingBar]"
U
0
Δ
V
❘
"\[RightBracketingBar]"
)
,
wherein
n is the sum of the quantity of peaks and the quantity of troughs.
14 . A wireless charging method applied to a wireless charging circuit comprising an oscillation circuit and a monitoring circuit that are sequentially connected, wherein the oscillation circuit comprises:
an excitation voltage source,
a half-bridge circuit, and
an LC series circuit that are connected in series, wherein:
the excitation voltage source is configured to provide a stable voltage for the LC series circuit;
the LC series circuit comprises an inductor and a resonance capacitor that are connected in series,
a first terminal of the LC series circuit is connected to a phase midpoint of the half-bridge circuit,
a second terminal of the LC series circuit is connected to the ground,
a phase midpoint of the LC series circuit is connected to the monitoring circuit, and is configured to output a resonant voltage signal during damped oscillation to the monitoring circuit; and the monitoring circuit comprises;
a voltage biasing module connected to the oscillation circuit and configured to:
receive the resonant voltage signal output by the oscillation circuit,
bias the resonant voltage signal, and
transmit a biased resonant voltage signal to a comparison module; and
a processing module, and
the comparison module is configured to receive the resonant voltage signal, and convert the resonant voltage signal into a digital square wave signal; and the method comprises:
receiving, by the processing module, the digital square wave signal, wherein the digital square wave signal is generated by converting the resonant voltage signal;
obtaining, by the processing module, a resonant voltage attenuation waveform during damped oscillation;
obtaining, based on the resonant voltage attenuation waveform, a first parameter that meets a first preset condition, wherein the first parameter comprises a quantity of peaks, a quantity of troughs, or a sum of the quantity of peaks and the quantity of troughs; and
determining, by the processing module, a quality factor Q based on the first parameter, and monitoring a foreign object based on the quality factor Q to obtain a monitoring result, wherein the quality factor Q represents a ratio of power stored in the oscillation circuit to a power loss in each cycle.
15 . The wireless charging method according to claim 14 , wherein the first preset condition is that in each oscillation cycle, a resonant voltage generated during damped oscillation is greater than a reference voltage; and when a voltage of the phase midpoint of the LC series circuit to ground reaches an amplitude voltage of the excitation voltage source Us, the damped oscillation occurs in the oscillation circuit to generate the resonant voltage.
16 . The wireless charging method according to claim 14 , wherein
the first parameter comprises the sum of the quantity of peaks and the quantity of troughs, and the sum is the sum of the quantity of peaks that meets the first preset condition and the quantity of troughs that meets the first preset condition.
17 . The wireless charging method according to claim 14 , wherein determining, by the processing module, the quality factor Q based on the first parameter further comprises:
determining, by the processing module based on the first parameter, the quality factor Q:
Q
=
n
·
π
m
·
ln
(
❘
"\[LeftBracketingBar]"
U
1
/
U
2
❘
"\[RightBracketingBar]"
)
,
wherein
n and m are both positive integers, m≥1, and U1 and U2 are any peak voltage or any trough voltage in the resonant voltage attenuation waveform.
18 . The wireless charging method according to claim 17 , wherein when m=2, the quality factor Q is:
Q
=
n
·
π
2
·
ln
(
❘
"\[LeftBracketingBar]"
U
1
/
U
2
❘
"\[RightBracketingBar]"
)
,
and
n is the sum of the quantity of peaks and the quantity of troughs.