Wireless power transmission systems for resonance tracking through low-frequency pulse control
The present disclosure belongs to the field of wireless power transmission technology, and specifically relates to a wireless power transmission system for resonance tracking through low-frequency pulse control. The system includes a power supply, a transmitting end, and a receiving end. The transmitting end includes a compensation circuit including a resonance capacitor and a transmitting coil that are connected in series with each other, the receiving end includes a receiving coil. The transmitting end also includes a bridge inverter. The wireless power transmission system completes resonance tracking through low-frequency pulse control of the bridge inverter, and realizes current self-oscillation through pulse charging of voltage. Compared with a conventional negative resistance self-oscillation manner, the present disclosure does not require additional complex negative resistance design and only needs to change an inverter control signal, so it has lower application cost and makes expansion of system function more flexible.
1. A wireless power transmission system for resonance tracking through low-frequency pulse control, comprising a power supply, a transmitting end, and a receiving end, wherein the transmitting end includes a compensation circuit including a resonance capacitor and a transmitting coil that are connected in series with each other, the receiving end includes a receiving coil; wherein
the transmitting end also includes a bridge inverter including:
a first metal-oxide-semiconductor field-effect transistor (MOSFET), wherein a drain of the first MOSFET is connected to a positive electrode of the power supply, a source of the first MOSFET is connected to an end of the resonance capacitor away from the transmitting coil, and a gate of the first MOSFET is a driving end; and
a second MOSFET, wherein a source of the second MOSFET is respectively connected to a negative electrode of the power supply and an end of the transmitting coil away from the resonance capacitor, a drain of the second MOSFET is connected to the source of the first MOSFET, and a gate of the second MOSFET is another driving end; and
the wireless power transmission system further comprises a control circuit, the control circuit including:
a controller respectively connected to the driving end of the first MOSFET and the driving end of the second MOSFET; and
a measurement circuit, wherein an output end of the measurement circuit is connected to a signal input end of the controller, the measurement circuit being used to obtain an oscillation period T o of a closed resonance loop formed by the transmitting end; wherein
when controlling the first MOSFET to be connected and the second MOSFET to be disconnected, the transmitting end is in a charging stage, and the transmitting end is connected to the power supply for charging;
when controlling the first MOSFET to be disconnected and the second MOSFET to be connected, by continuously providing a low-frequency pulse control signal to the driving end of the second MOSFET, the second MOSFET is configured to output a low-frequency pulse voltage, the transmitting end forms the closed resonance loop and generates a self-oscillation, the transmitting coil generates an induced magnetic field, and the receiving coil at the receiving end obtains power through a magnetic induction phenomenon to realize a wireless power transmission; and
after initialization, through the controller, a fixed low-frequency pulse voltage is controlled to be output from the second MOSFET for resonance starting, and the controller obtains the oscillation period T o of the closed resonance loop through the measurement circuit, and adjusts, based on relationships among the oscillation period T o , a pulse time τ, and a control frequency f c , the pulse time τ and the control frequency f c of the low-frequency pulse control signal.
2. The wireless transmission system of claim 1 , wherein the first MOSFET and the second MOSFET are N-channel MOSFETs.
3. The wireless power transmission system of claim 1 , wherein the relationships among the oscillation period T o and the pulse time τ and the control frequency f c of the low-frequency pulse control signal satisfy:
τ
=
T
o
/
2
f
c
=
1
(
n
+
1
)
T
o
,
n
∈
N
+
where, n≥1 and nϵZ + .
4. The wireless power transmission system of claim 3 , wherein a duty cycle D of the low-frequency pulse control signal satisfies:
D
=
τ
f
c
=
1
2
(
n
+
1
)
.
5. The wireless power transmission system of claim 4 , wherein when the control circuit adjusts the pulse time τ and the control frequency f c of the low-frequency pulse control signal based on the relationships among the oscillation period T o , the pulse time τ, and the control frequency f c , n takes a value of 1, the control frequency f c is half of the oscillation period T o , and the duty cycle D is fixed at 25%.
6. The wireless power transmission system of claim 1 , wherein the measurement circuit adopts a zero crossing current detection circuit.
7. The wireless power transmission system of claim 4 , wherein when the controller controls the second MOSFET to output the fixed low-frequency pulse voltage for resonance starting, control parameters of the low-frequency pulse control signal satisfy:
the control frequency f c =40 Khz, the duty cycle D=10%, and the pulse time τ=10% of T c , where T c denotes a charging period.