Wireless charging system and wireless charging method

Abstract

The invention discloses a wireless charging system and a wireless charging method, and belongs to the technical field of wireless charging, the wireless charging system comprises a DC-to-AC unit, an AC-to-AC unit and an AC-to-DC unit which are connected in sequence; the DC-to-AC unit comprises a plurality of DC-to-AC subunits which are connected in parallel, each DC-to-AC subunit comprises an isolation circuit, and the output power is adjusted by adjusting the parameters of the isolation circuits and the number of the DC-to-AC subunits; the alternating current-to-alternating current unit comprises a mode switch, and the alternating current output by the direct current-to-alternating current unit is converted into constant-voltage alternating current output or constant-current alternating current output by adjusting the connection mode of the mode switch; and the alternating current-to-direct current unit is used for converting the alternating current output by the alternating current-to-alternating current unit into direct current and outputting the direct current. Low-power-consumption high-power output is achieved by adjusting the number of the DC-to-AC subunits and adjusting parameters of the isolation circuit, constant-current and constant-voltage double-model output is achieved at the same time, and expandability and applicability of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging technology, and in particular to a wireless charging system and a wireless charging method. Background Art

[0002] Wireless charging technology is a contactless transmission of electrical energy, allowing power to be transferred from a power source to a receiving device without the need for a physical connection. Based on the principles of electromagnetic fields, wireless charging technology typically uses magnetic or electric fields to achieve energy transmission. It is primarily used in consumer electronics, electric vehicles, robotics, and energy transmission, and is characterized by flexibility, convenience, and safety. Wireless charging has become an emerging charging technology in the 21st century, offering broad application prospects. With the advancement of science and technology, wireless charging applications will continue to expand, and demand for its use will continue to grow. Wireless charging technology is popular for its convenience, safety, and contactless nature. As the technology matures, wireless charging has gained widespread application and continues to develop. Simultaneously, the demand for systems capable of transmitting greater power is also increasing.

[0003] Traditional single-input, single-output wireless power transmission systems are unable to achieve high power due to the limited voltage and current tolerance of switching devices. Traditional wireless power transmission systems can provide approximately tens of kilowatts of power. However, with the continuous advancement of technology and the increasing needs of people, the power demand for electric vehicle charging may reach hundreds of kilowatts or more in the future, and the demand for electric ships and electric rail trains may escalate to 1MW. However, the power of traditional wireless charging systems is limited by power semiconductor devices, preventing major breakthroughs. The operating frequency of high-power wireless charging systems is typically between 20 kHz and 85 kHz. At high frequencies, insulated gate bipolar transistors (IGBTs) have difficulty maintaining low loss and high efficiency. While silicon-based metal oxide semiconductor field-effect transistors (MOSFETs) have high-frequency capabilities, they cannot provide the necessary current capacity.

[0004] Therefore, there is an urgent need for a wireless charging system and a wireless charging method that can solve the technical problems in the existing technology that are unable to achieve adjustable high-power output with low loss and constant current and constant voltage dual-mode output. Summary of the Invention

[0005] In view of this, it is necessary to provide a wireless charging system and a wireless charging method that can solve the technical problems in the existing technology that are unable to achieve adjustable high-power output with low loss and constant current and constant voltage dual-mode output.

[0006] To achieve the above-mentioned object, in one aspect, the present invention provides a wireless charging system, comprising: a DC-to-AC unit, an AC-to-AC unit, and an AC-to-DC unit connected in sequence; The DC-AC unit comprises a plurality of DC-AC sub-units connected in parallel, each of which comprises an isolation circuit, and the output power is adjusted by adjusting the parameters of the isolation circuit and the number of the DC-AC sub-units; The AC-to-AC unit includes a mode switch, and by adjusting the connection mode of the mode switch, the AC power output by the DC-to-AC unit is converted into a constant voltage AC output or a constant current AC output; The AC to DC unit is used to convert the AC power output by the AC to AC unit into DC power for output.

[0007] In one possible implementation, the DC-AC sub-unit further includes a full-bridge inverter circuit; The full-bridge inverter circuit includes a first MOS transistor, a second MOS transistor, a third MOS transistor and a fourth MOS transistor; The first MOS transistor and the third MOS transistor are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively. The second MOS transistor and the fourth MOS transistor are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively.

[0008] In one possible implementation, the isolation circuit includes a first inductor, a second inductor, and a first capacitor; One end of the first inductor is connected to one end of the first MOS transistor and the third MOS transistor respectively, and the other end is connected to one end of the second inductor and the first capacitor; The other end of the second inductor and the other end of the first capacitor are connected to the input end of the AC-to-AC unit; One end of the first capacitor is connected to one end of the first inductor and the second inductor respectively, and the other end is connected to the second MOS transistor and the fourth MOS transistor respectively.

[0009] In one possible implementation, the AC-to-AC unit further includes a second capacitor, a first coupling coil, a second coupling coil, a third inductor, a third capacitor, and a fourth capacitor; The second capacitor and the first coupling coil are connected in series and then connected to the output end of the DC-AC sub-unit; The second coupling coil, the third capacitor and the fourth capacitor are sequentially connected in series and then connected to the input end of the AC-DC unit. One end of the third inductor is connected to one end of the second inductor.

[0010] In one possible implementation, the mode switch is a single-pole double-throw switch, comprising a common contact, a first contact, and a second contact; The common contact is connected to one end of the third capacitor and the fourth capacitor; The first contact is connected to the second inductor and one end of the third capacitor; The second contact is connected to one end of the third inductor; When the common contact is connected to the first contact, the third inductor is disconnected, the third capacitor is short-circuited, and the AC-to-AC unit is switched to a constant voltage output state; When the common contact is connected to the second contact, the third inductor and the third capacitor are connected to the AC-to-AC unit, and the AC-to-AC unit switches to a constant current output state.

[0011] In one possible implementation, the AC-DC unit includes an uncontrolled rectifier unit and a fifth capacitor; The first diode and the third diode are connected in series to obtain a first branch; The second diode and the fourth diode are connected in series to obtain a second branch; The first branch, the second mass and the fifth capacitor are connected in parallel in sequence; Two ends of the fifth capacitor are externally connected to a load resistor.

[0012] In a second aspect, the present invention further provides a wireless charging method, which is applied to the wireless charging system as described above, and the wireless charging method includes: Determine the charging mode according to the real-time charging status of the charging device; Determine the number of DC-to-AC subunits and the parameters of the isolation circuit based on the charging power of the device to be charged; Based on the wireless charging system, wireless charging is performed on the device to be charged according to the number of the DC-AC subunits, the parameters of the isolation circuit and the charging mode.

[0013] In one possible implementation, determining the parameters of the isolation circuit according to the charging power of the device to be charged includes: Equivalently converting the isolation circuit into a T-type circuit, constructing a relationship between input voltage, output current and isolation circuit parameters; Determine the output current of the isolation circuit according to the charging power of the charging load and the number of DC-to-AC sub-units; Parameters of the optimal isolation circuit are determined according to the output current and input voltage of the isolation circuit.

[0014] In one possible implementation, the relationship between the input voltage, output current, and isolation circuit parameters is: , in, I is the output current of the isolation circuit, L is the parameter value of the isolation circuit, j is the imaginary unit, is the system angular frequency, is the system frequency, is the input DC voltage.

[0015] In one possible implementation, determining a charging mode according to a real-time charging state of a charging device includes: Obtaining the real-time charging status of the device to be charged, wherein the charging status includes a low-voltage state and a high-voltage state; When the voltage of the device to be charged is less than a preset voltage threshold, the charging mode is set to a constant current charging mode; When the voltage of the device to be charged is greater than or equal to a preset voltage threshold, the charging mode is set to a constant voltage charging mode.

[0016] The beneficial effects of the present invention are: a wireless charging system is constructed by sequentially connecting a DC-to-AC unit, an AC-to-AC unit and an AC-to-DC unit; wherein the DC-to-AC unit includes a plurality of DC-to-AC sub-units connected in parallel, and the DC-to-AC sub-unit includes an isolation circuit, and the output power is adjusted by adjusting the parameters of the isolation circuit and the number of DC-to-AC sub-units. The isolation circuit makes each DC-to-AC sub-unit independent, and by appropriately increasing the number of independent DC-to-AC sub-units, high-power output can be achieved. At the same time, by adjusting the parameters of the isolation circuit, the output gain of the isolation circuit is adjusted, thereby adjusting the output power of the DC-to-AC sub-unit, and further adjusting the output power of the system; the AC-to-AC unit includes a mode switch, and by adjusting the connection method of the mode switch, the AC power output by the DC-to-AC unit is converted into a constant voltage AC output or a constant current AC output; the AC-to-DC unit is used to convert the AC power output by the AC-to-AC unit into a DC power output. The present invention adjusts the power supply of the entire system by adjusting the number of DC-to-AC sub-units and the parameters of the isolation circuit, achieving high-power output with low loss, thereby matching charging devices with different high-power requirements, greatly improving the scalability and flexibility of the system. By changing the topological state of the AC-to-AC unit through the mode switch, two working modes of constant current output or constant voltage output can be realized without changing its frequency, further improving the applicability and energy efficiency performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic structural diagram of an embodiment of a wireless charging system provided by the present invention; Figure 2 A schematic diagram of a T-type circuit provided by the present invention; Figure 3 A schematic diagram of a T-type circuit equivalent to the isolation circuit provided by the present invention; Figure 4 An equivalent circuit diagram of the wireless charging system provided by the present invention; Figure 5 An equivalent circuit diagram of the AC-to-AC unit provided by the present invention; Figure 6 The equivalent circuit diagram of the AC-to-AC unit with constant voltage output provided by the present invention; Figure 7 The equivalent circuit diagram of the AC-to-AC unit with constant current output provided by the present invention; Figure 8 A schematic structural diagram of an embodiment of the wireless charging method provided by the present invention; Figure 9 The present invention provides Figure 8 FIG. 8 is a flow chart of an embodiment of step S801 in FIG. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] In the description of the embodiments of the present invention, unless otherwise specified, “a plurality of” means two or more.

[0021] The terms "first," "second," and so on, used in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature designated as "first" or "second" may explicitly or implicitly include at least one such feature.

[0022] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] The present invention provides a wireless charging system and a wireless charging method, which are described below respectively.

[0024] In some embodiments of the present invention, Figure 1 As shown, Figure 1 This is a schematic structural diagram of an embodiment of the wireless charging system provided by the present invention, which includes a DC-to-AC unit 100, an AC-to-AC unit 200, and an AC-to-DC unit 300 connected in sequence; The DC-to-AC unit 100 includes a plurality of DC-to-AC subunits 110 connected in parallel. The DC-to-AC subunits 110 include an isolation circuit 112. The output power is adjusted by adjusting the parameters of the isolation circuit 112 and the number of the DC-to-AC subunits 110. The AC-to-AC unit 200 includes a mode switch S, which converts the AC power output by the DC-to-AC unit 100 into a constant voltage AC output or a constant current AC output by adjusting the connection mode of the mode switch S; The AC-DC unit 300 is used to convert the AC power output by the AC-DC unit 200 into DC power for output.

[0025] It should be noted that the input end of the DC-to-AC unit 100 is connected to a DC power supply, which can be powered by a single power supply or multiple power supplies. A power supply is provided for each DC-to-AC sub-unit 110. The DC-to-AC sub-unit 110 first converts the DC power into a square wave output, and outputs constant current AC power in several isolation circuits 112. Several DC-to-AC sub-units 110 are connected in parallel, which is similar to the parallel connection of several AC power supplies. In the AC-to-AC unit 200, the topological state is changed by the mode switch S, so that it can achieve constant current AC output or constant voltage AC output under constant current input. In this way, by selecting the appropriate time to switch the switch, the battery charging requirements of constant current first and then constant voltage or constant voltage first and then constant current can be met.

[0026] This embodiment constructs a wireless charging system by sequentially connecting a DC-to-AC unit 100, an AC-to-AC unit 200, and an AC-to-DC unit 300. The DC-to-AC unit 100 includes a plurality of DC-to-AC sub-units 110 connected in parallel. The DC-to-AC sub-units 110 include an isolation circuit 112. The output power is adjusted by adjusting the parameters of the isolation circuit 112 and the number of DC-to-AC sub-units 110. The isolation circuit 112 makes each DC-to-AC sub-unit 110 independent. By appropriately increasing the number of independent DC-to-AC sub-units 110, high power output can be achieved. The output gain of the isolation circuit 112 is adjusted by adjusting the parameters of the isolation circuit 112, thereby adjusting the output power of the DC-to-AC sub-unit 110 and further adjusting the output power of the system. The AC-to-AC unit 200 includes a mode switch S. By adjusting the connection mode of the mode switch S, the AC power outputted by the DC-to-AC unit 100 is converted into a constant voltage AC output or a constant current AC output. The AC-to-DC unit 300 is used to convert the AC power outputted by the AC-to-AC unit 200 into a DC power output. This embodiment adjusts the power supply of the entire system by adjusting the number of DC-to-AC sub-units 110 and adjusting the parameters of the isolation circuit 112, thereby achieving high power output with low loss, thereby matching charging devices with different power requirements, greatly improving the scalability and flexibility of the system. By changing the topological state of the AC-to-AC unit 200 through the mode switch, two working modes of constant current output or constant voltage output are realized without changing its frequency, further improving the applicability and energy efficiency performance of the system.

[0027] In some embodiments of the present invention, the DC-to-AC subunit 110 further includes a full-bridge inverter circuit 111; The full-bridge inverter circuit 111 includes a first MOS transistor Q11, a second MOS transistor Q12, a third MOS transistor Q13 and a fourth MOS transistor Q14; The first MOS transistor Q11 and the third MOS transistor Q13 are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively. The second MOS transistor Q12 and the fourth MOS transistor Q14 are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively.

[0028] Specifically, the first MOS transistor Q11 and the fourth MOS transistor Q14 , the second MOS transistor Q12 and the third MOS transistor Q13 are alternately turned on to convert the input DC voltage into a high-frequency square wave signal.

[0029] In some embodiments of the present invention, the isolation circuit 112 includes a first inductor L1, a second inductor L2, and a first capacitor C1; One end of the first inductor L1 is connected to one end of the first MOS transistor Q11 and the third MOS transistor Q13 respectively, and the other end is connected to the second inductor L2 and one end of the first capacitor C1; The other end of the second inductor L2 and the other end of the first capacitor C1 are connected to the input end of the AC-to-AC unit 200; One end of the first capacitor C1 is connected to one end of the first inductor L1 and one end of the second inductor L2 , and the other end is connected to the second MOS transistor Q12 and the fourth MOS transistor Q14 .

[0030] Specifically, the isolation circuit 112 is used to adjust and filter the high-frequency square wave signal output by the full-bridge inverter circuit 111 , and finally convert it into a high-quality sinusoidal wave output.

[0031] Furthermore, the full-bridge inverter circuit 111 converts the DC voltage into a square wave voltage, and the conversion formula is: , in, is the square wave voltage output by the full-bridge inverter circuit 111, is the DC input voltage of the DC-to-AC subunit; The isolation circuit 112 can be equivalent to a T-type circuit. First, in the T-type circuit, as shown in FIG. Figure 2 As shown, Kirchhoff's voltage law KVL is used to analyze each loop in the circuit and establish a voltage equation. Kirchhoff's current law KCL is used to analyze the circuit nodes and establish a current equation: , in, and are the input voltage and input current of the T-type circuit, and are the output voltage and output current of the T-type circuit, are the three impedances of the T-type circuit; Further convert the above voltage equation and current equation into T matrix: , in, is the intermediate variable of the T matrix; According to this T matrix, when When , the matrix can be simplified to finally obtain the relationship between input voltage, input current and output voltage and output voltage: ,Right now , According to the relationship between input voltage, input current, output voltage and output voltage, when the T-type circuit meets the impedance matching condition, it satisfies When the input voltage is kept constant, the T-type circuit can achieve constant current output; when the input current is kept constant, the T-type circuit can achieve constant voltage output. Furthermore, when the load resistance of the T-type circuit is R When , the input impedance is calculated as: , in, is the input impedance, R is the load resistance, when the impedance and When the value is imaginary, the impedance and The product of ) has a clear real number characteristic, which directly leads to the input impedance It is expressed in pure real number form. When the load has purely resistive characteristics, the input impedance of the T-type circuit also maintains resistive characteristics in both CV and CC output modes, and the voltage and current at the input end are in the same phase, thus achieving zero power absorption of the T-type circuit, which can not only maximize the energy transmission efficiency, but also effectively reduce reactive power loss.

[0032] Similarly, the isolation circuit 112 is equivalent to a T-type circuit, such as Figure 3 As shown, when the first inductor L1, the second inductor L2, and the first capacitor C1 meet the following conditions, they can be equivalent to the above-mentioned zero-power-absorbing T-type circuit. At this time, the isolation circuit 112 outputs a sinusoidal voltage with no power loss. The conditions that the first inductor L1, the second inductor L2, and the first capacitor C1 need to meet are: , in, is the system angular frequency, is the system frequency, is the inductance of the first inductor L1, is the inductance of the second inductor L2, is the capacitance value of the first capacitor C1; The entire DC-to-AC subunit 110 is equivalent to an AC power supply, and the inductance value of the first inductor L1 and the inductance value of the second inductor L2 are set to the same value. L ,Right now, , the relationship between the input voltage and output current of this AC power supply is: , in, L is the parameter of the inductor in the isolation circuit 112, is a square wave voltage, For the input DC voltage, each DC to AC sub-unit 110 can adjust L The parameter value is used to change the size of the AC current output by each DC-AC sub-unit 110, and further adjust the output power of each DC-AC sub-unit 110 without affecting the normal operation of the system.

[0033] In addition, the isolation circuit 112 isolates the DC-AC sub-unit 110, making it an independent entity, so that it is not affected by other circuits. Each DC-AC sub-unit 110 is equivalent to an AC current source, so the entire charging system can be equivalent to a power supply system with multiple AC sources. The specific equivalent diagram is shown in FIG. Figure 4 As shown, Figure 4 In FIG, I1, I2 to In are n AC current sources equivalent to the n DC-to-AC sub-units 110.

[0034] In some embodiments of the present invention, the AC-to-AC unit further includes a second capacitor C2, a first coupling coil L4, a second coupling coil L5, a third inductor L3, a third capacitor C3, and a fourth capacitor C4; The second capacitor C2 and the first coupling coil L4 are connected in series and then connected to the output end of the DC-to-AC sub-unit 110; The second coupling coil L5, the third capacitor C3 and the fourth capacitor C4 are connected in series and connected to the input end of the AC-DC unit 300. One end of the third inductor L3 is connected to one end of the second coupling coil L5, and the other end is connected to the mode switch S.

[0035] The second capacitor C2 and the first coupling coil L4 constitute the front stage of the AC-to-AC unit, and the second coupling coil L5, the third capacitor C3 and the fourth capacitor C4 constitute the rear stage of the AC-to-AC unit.

[0036] In some embodiments of the present invention, the mode switch S is a single-pole double-throw switch, comprising a common contact S0, a first contact S1, and a second contact S2; The common contact S0 is connected to one end of the third capacitor C3 and the fourth capacitor C4; The first contact S1 is connected to one end of the second inductor C2 and the third capacitor C3; The second contact S2 is connected to one end of the third inductor C3; When the common contact S0 is connected to the first contact S1, the third inductor L3 is disconnected, the third capacitor C3 is short-circuited, and the AC-to-AC unit 200 switches to a constant voltage output state; When the common contact S0 is connected to the second contact S2 , the third inductor L3 and the third capacitor C3 are connected to the AC-to-AC unit 200 , and the AC-to-AC unit 200 switches to a constant current output state.

[0037] Specifically, the AC to AC unit 200 realizes the switching between AC constant current output and AC constant voltage output through the mode switch S. The equivalent circuit diagram of the AC to AC unit 200 is as follows: Figure 5 As shown, M1, M2 and M3 are the coupling simulation circuits of the first coupling coil L4 and the second coupling coil L5, and the mode switch S is connected. When the common contact S0 is connected to the first contact S1, the third inductor L3 is disconnected and the third capacitor C3 is short-circuited. The equivalent circuit diagram is shown in FIG. Figure 6 As shown, the second coupling coil L5 and the fourth capacitor C4 are in series resonance, and the second capacitor C2 and the first coupling coil L4 are in series resonance, wherein when the second capacitor C2, the fourth capacitor C4, the first coupling coil L4 and the second coupling coil L5 meet When the AC-to-AC unit 200 is equivalent to a T-type circuit, the constant AC current output by the DC-to-AC unit 100 is converted into a constant AC voltage output. At this time, the relationship between the input voltage and current and the output voltage and current in the equivalent T-type circuit is: , , in, is the input voltage, is the input current, is the system angular frequency, is the system frequency, j is the imaginary unit, is the output voltage, is the output current, M is the coupling value, is the current value output by the kth DC-AC subunit, n is the total number of DC-AC subunits, is the total resistance of the AC-DC unit, R is the load resistance value of the AC-DC unit, is the impedance of the AC to AC unit when outputting constant voltage.

[0038] According to the relationship between the above-mentioned input voltage and current and the output voltage and current, it can be seen that when the first contact and the common contact are connected, the AC-to-AC unit outputs constant voltage AC power. When the input of the AC-to-AC unit is the same-phase voltage and current, the corresponding output is also the same-phase voltage and current, achieving zero power absorption and greatly reducing the reactive loss of the system.

[0039] Furthermore, when the common contact S0 is connected to the second contact S2, the third inductor L3 and the third capacitor C3 are connected to the AC-to-AC unit 200, and the third capacitor C3 is equivalent to two capacitors C31 and C32 connected in series. Figure 7As shown, the second capacitor C2 and the first coupling coil L4 are in series resonance, and the second coupling coil L5 and the capacitor C31 are in series resonance, wherein when the second capacitor C2, the capacitor C31, the first coupling coil L4 and the second coupling coil L5 meet When the AC-to-AC unit 200 is equivalent to a cascade of two T-type circuits, the constant AC current output by the DC-to-AC unit 100 is converted into a constant AC voltage output through the first T-type circuit, and then converted into a constant AC current output through the second T-type circuit. At this time, the relationship between the input voltage and current and the output voltage and current in the equivalent T-type circuit is: , , in, is the input voltage, is the input current, is the output voltage after the input voltage passes through the first T-type circuit, is the output current after the input current passes through the first T-type circuit, is the system angular frequency, is the system frequency, j is the imaginary unit, is the output voltage after passing through the second T-type circuit, is the output current after passing through the second T-type circuit, M is the coupling value, is the current value output by the kth DC-AC subunit, n is the total number of DC-AC subunits, is the total resistance of the AC-DC unit, R is the load resistance value of the AC-DC unit, Z ( CC ) is the impedance of the AC-to-AC unit when outputting constant current, is the capacitance value of the fourth capacitor, is the inductance value of the third inductor.

[0040] According to the relationship between the above-mentioned input voltage and current and the output voltage and current, it can be seen that when the second contact and the common contact are connected, the AC-to-AC unit outputs constant current AC. When the input of the AC-to-AC unit is the same-phase voltage and current, its output is also the same-phase voltage and current, thus achieving zero power absorption and greatly reducing the reactive loss of the system.

[0041] In some embodiments of the present invention, the AC-DC unit 300 includes an uncontrolled rectifier unit 310 and a fifth capacitor C5; The uncontrolled rectifier unit 310 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; The first diode D1 and the third diode D3 are connected in series to form a first branch; The second diode D2 and the fourth diode D4 are connected in series to form a second branch; The first branch, the second mass and the fifth capacitor C5 are connected in parallel in sequence; The two ends of the fifth capacitor C5 are externally connected to a load resistor R.

[0042] Specifically, the uncontrolled rectifier unit 310 connects four diodes in two groups in series and then in parallel to form an output circuit together with the fifth capacitor C5, performs full-wave rectification, and outputs direct current with small pulsation. Among them, the fifth capacitor C5 filters the direct current output by the uncontrolled rectifier unit 310, charges when the voltage rises, and discharges when the voltage drops, thereby suppressing voltage fluctuations.

[0043] Based on the above wireless charging system, the embodiment of the present invention also provides a wireless charging method, which can implement the technical solution described in the above wireless charging system embodiment, such as Figure 8 As shown, the method includes: S801: Determine a charging mode according to a real-time charging status of a charging device; S802: Determine the number of DC-to-AC subunits and parameters of the isolation circuit based on the charging power of the device to be charged; S803: Based on the wireless charging system, wirelessly charge the device to be charged according to the number of the DC-AC subunits, the parameters of the isolation circuit, and the charging mode.

[0044] It should be noted that by setting up multiple independent DC-to-AC sub-units connected in parallel, the output power of the DC power supply is amplified. At the same time, the DC-to-AC sub-unit is isolated through an isolation circuit so that it is not affected by circuits such as the AC-to-AC unit or other DC-to-AC sub-units. In addition, by adjusting the parameters of the isolation circuit, the output power gain and zero power absorption are achieved, thereby further improving the output power of the system; the topology circuit of the AC-to-AC unit is changed through a mode switch to achieve constant current AC output or constant voltage AC output; finally, the constant current AC is converted into constant current DC or the constant voltage AC is converted into constant voltage DC through the AC-to-DC unit to charge the charging device.

[0045] Specifically, different charging devices have different requirements for charging power. First, the charging power of the device to be charged is determined, the number of DC-to-AC sub-units is determined, and the output current of the DC-to-AC sub-units is further calculated. Based on this output current and the input voltage of the DC power supply, as well as the relationship between the input voltage, output current and isolation circuit parameters, the parameter value of the isolation circuit is calculated. This parameter value is the inductance value of the first inductor and the second inductor in the isolation circuit.

[0046] In some embodiments of the present invention, Figure 9 As shown, Figure 9 The present invention provides Figure 8 The flowchart of an embodiment of step S801 in FIG. 1 is a flowchart of adjusting the output power by adjusting the parameters of the isolation circuit, including: S901. Equivalently convert the isolation circuit to a T-type circuit, and construct a relationship between the input voltage, output current, and isolation circuit parameters. The relationship is: , in, I is the output current of the isolation circuit, j is the imaginary unit, is the system angular frequency, is the system frequency, L is the parameter value of the isolation circuit, is the input DC voltage.

[0047] S902. Determine the output current of the isolation circuit according to the charging power of the charging load and the number of DC-to-AC subunits; S903: Determine optimal isolation circuit parameters according to the output current and input voltage of the isolation circuit.

[0048] In some embodiments of the present invention, controlling a constant current output or a constant voltage output by changing a mode switch includes: Obtaining the real-time charging status of the device to be charged, wherein the charging status includes a low-voltage state and a high-voltage state; When the voltage of the device to be charged is less than a preset voltage threshold, the charging mode is set to a constant current charging mode; When the voltage of the device to be charged is greater than or equal to a preset voltage threshold, the charging mode is set to a constant voltage charging mode.

[0049] Specifically, by monitoring the current and voltage values ​​of the device to be charged, when the voltage of the battery to be charged is low, that is, lower than the preset voltage threshold, the charging system is switched to a constant current charging state to ensure that the charging current is stable. When the battery voltage is greater than or equal to the preset threshold, the voltage of the device to be charged tends to be stable, and the charging system is switched to a constant voltage charging state to gradually reduce the current to prevent overcharging.

[0050] The wireless charging system provided by the present invention is introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core concept of the present invention. At the same time, for those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A wireless charging system, characterized in that: include: a DC-to-AC unit, an AC-to-AC unit, and an AC-to-DC unit connected in sequence; The DC-AC unit comprises a plurality of DC-AC sub-units connected in parallel, each of which comprises an isolation circuit, and the output power is adjusted by adjusting the parameters of the isolation circuit and the number of the DC-AC sub-units; The AC-to-AC unit includes a mode switch, and by adjusting the connection mode of the mode switch, the AC power output by the DC-to-AC unit is converted into a constant voltage AC output or a constant current AC output; The AC to DC unit is used to convert the AC power output by the AC to AC unit into DC power for output.

2. The wireless charging system according to claim 1, wherein: The DC to AC sub-unit further includes a full-bridge inverter circuit; The full-bridge inverter circuit includes a first MOS transistor, a second MOS transistor, a third MOS transistor and a fourth MOS transistor; The first MOS transistor and the third MOS transistor are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively. The second MOS transistor and the fourth MOS transistor are connected in series, and their two ends are connected to the positive and negative poles of the DC power supply respectively.

3. The wireless charging system according to claim 2, wherein: The isolation circuit includes a first inductor, a second inductor and a first capacitor; One end of the first inductor is connected to one end of the first MOS transistor and the third MOS transistor respectively, and the other end is connected to one end of the second inductor and the first capacitor; The other end of the second inductor and the other end of the first capacitor are connected to the input end of the AC-to-AC unit; One end of the first capacitor is connected to one end of the first inductor and the second inductor respectively, and the other end is connected to the second MOS transistor and the fourth MOS transistor respectively.

4. The wireless charging system according to claim 1, wherein: The AC-to-AC unit further includes a second capacitor, a first coupling coil, a second coupling coil, a third inductor, a third capacitor, and a fourth capacitor; The second capacitor and the first coupling coil are connected in series and then connected to the output end of the DC-AC sub-unit; The second coupling coil, the third capacitor and the fourth capacitor are sequentially connected in series and then connected to the input end of the AC-DC unit. One end of the third inductor is connected to one end of the second inductor.

5. The wireless charging system according to claim 4, wherein: The mode switch is a single-pole double-throw switch, comprising a common contact, a first contact and a second contact; The common contact is connected to one end of the third capacitor and the fourth capacitor; The first contact is connected to the second inductor and one end of the third capacitor; The second contact is connected to one end of the third inductor; When the common contact is connected to the first contact, the third inductor is disconnected, the third capacitor is short-circuited, and the AC-to-AC unit is switched to a constant voltage output state; When the common contact is connected to the second contact, the third inductor and the third capacitor are connected to the AC-to-AC unit, and the AC-to-AC unit switches to a constant current output state.

6. The wireless charging system according to claim 1, wherein: The AC-DC unit includes an uncontrolled rectifier unit and a fifth capacitor; The uncontrolled rectifier unit includes a first diode, a second diode, a third diode and a fourth diode; The first diode and the third diode are connected in series to obtain a first branch; The second diode and the fourth diode are connected in series to obtain a second branch; The first branch, the second mass and the fifth capacitor are connected in parallel in sequence; Two ends of the fifth capacitor are externally connected to a load resistor.

7. A wireless charging method, characterized in that: Based on the wireless charging system according to any one of claims 1 to 6, the wireless charging method includes: Determine the charging mode according to the real-time charging status of the charging device; Determine the number of DC-to-AC subunits and the parameters of the isolation circuit based on the charging power of the device to be charged; Based on the wireless charging system, wireless charging is performed on the device to be charged according to the number of the DC-AC subunits, the parameters of the isolation circuit and the charging mode.

8. The wireless charging method according to claim 7, wherein: Determine the parameters of the isolation circuit based on the charging power of the device to be charged, including: Equivalently converting the isolation circuit into a T-type circuit, constructing a relationship between input voltage, output current and isolation circuit parameters; Determine the output current of the isolation circuit according to the charging power of the charging load and the number of DC-to-AC sub-units; Parameters of the optimal isolation circuit are determined according to the output current and input voltage of the isolation circuit.

9. The wireless charging method according to claim 8, wherein: The relationship between the input voltage, output current and isolation circuit parameters is: ， in, I is the output current of the isolation circuit, L is the parameter value of the isolation circuit, j is the imaginary unit, is the system angular frequency, is the system frequency, is the input DC voltage.

10. The wireless charging method according to claim 7, wherein: Determine the charging mode based on the real-time charging status of the charging device, including: Obtaining the real-time charging status of the device to be charged, wherein the charging status includes a low-voltage state and a high-voltage state; When the voltage of the device to be charged is less than a preset voltage threshold, the charging mode is set to a constant current charging mode; When the voltage of the device to be charged is greater than or equal to a preset voltage threshold, the charging mode is set to a constant voltage charging mode.

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