Wireless transmitter module, charging device and charging system

Abstract

The embodiments of the present application relate to a wireless transmission module, a charging device and a charging system. The wireless transmission module includes: an inverter circuit, including multiple parasitic switch tubes, for receiving a DC signal and converting the DC signal into a first AC signal, the voltage of the first AC signal having the same phase as the current; a first resonant circuit, connected to the inverter circuit, for performing resonance compensation on the first AC signal; a transmitting coil, connected to the first resonant circuit, for transmitting an electromagnetic signal according to the first AC signal after resonance compensation; a freewheeling circuit, connected to the inverter circuit, for providing a target current to the inverter circuit within the dead time of the inverter circuit, the target current being used to charge and discharge the parasitic capacitance of each parasitic switch tube in the inverter circuit. By effectively charging and discharging the parasitic capacitance through the target current, the switching performance of the inverter circuit is improved, and the switching loss is further reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of wireless charging technology, and in particular to a wireless transmission module, a charging device, and a charging system. Background Art

[0002] Mobile devices are playing an increasingly important role in our lives, and their charging technology is developing rapidly. Wireless charging technology, among other things, eliminates the need for a physical charging cable. Simply bringing the charging device close to or in contact with a wireless charging device allows charging, significantly improving charging convenience. However, existing wireless charging devices consume high power and cannot meet user needs. Summary of the Invention

[0003] Based on this, it is necessary to provide a wireless transmission module, charging device and charging system with low power consumption to address the above technical problems.

[0004] In a first aspect, the present application provides a wireless transmission module, comprising:

[0005] an inverter circuit, comprising a plurality of parasitic switching tubes, for receiving a DC signal and converting the DC signal into a first AC signal, wherein the voltage and current of the first AC signal are in phase with each other;

[0006] a first resonant circuit, connected to the inverter circuit, for performing resonance compensation on the first AC signal;

[0007] a transmitting coil, connected to the first resonant circuit, and configured to transmit an electromagnetic signal according to the first AC signal after resonance compensation;

[0008] A freewheeling circuit is connected to the inverter circuit and is used to provide a target current to the inverter circuit during the dead time of the inverter circuit, and the target current is used to charge and discharge the parasitic capacitance of each parasitic switch tube in the inverter circuit.

[0009] In a second aspect, the present application provides a wireless charging device, comprising:

[0010] Such as the wireless transmission module mentioned above;

[0011] The controller is connected to the inverter circuit of the wireless transmission module and is used to control the inverter circuit to alternately switch working modes so that the inverter circuit converts the received DC signal into the first AC signal.

[0012] In a third aspect, the present application provides a wireless charging system, including a terminal and the wireless charging device as described above, wherein the terminal includes:

[0013] a receiving coil, electromagnetically coupled to the transmitting coil of the wireless charging device, for receiving the electromagnetic signal;

[0014] The second resonant circuit is connected to the receiving coil and is used to generate a second AC signal according to the electromagnetic signal, and the second AC signal is used to power a load circuit of the terminal.

[0015] The wireless transmission module, charging device, and charging system described above can reduce the reactive power of the first resonant circuit by aligning the output voltage and current of the inverter circuit. Furthermore, because the freewheeling circuit provides a target current to the inverter circuit during the dead time of the inverter circuit's mode switching, the target current can effectively charge and discharge the parasitic capacitance, thereby improving the switching performance of the inverter circuit and further reducing switching losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic structural diagram of a wireless transmission module according to an embodiment;

[0018] Figure 2 is a circuit diagram of a full-bridge inverter circuit according to an embodiment;

[0019] Figure 3 is a current schematic diagram when the full-bridge inverter circuit operates in the first operating mode;

[0020] Figure 4 is a current diagram when the full-bridge inverter circuit operates in the second operating mode;

[0021] Figure 5 Schematic diagram of the current in the first stage when the inverter circuit switches from the first working mode to the second working mode when the freewheeling circuit is not provided;

[0022] Figure 6 is a current diagram of the second stage when the inverter circuit switches from the first working mode to the second working mode when the freewheeling circuit is not provided;

[0023] Figure 7 This is a second structural diagram of a signal transmission module according to an embodiment;

[0024] Figure 8 This is a third structural diagram of a wireless transmission module according to an embodiment;

[0025] Figure 9 This is a schematic diagram of the structure of a wireless charging system according to an embodiment;

[0026] Figure 10 This is a simulation signal waveform diagram of a wireless transmission module according to an embodiment;

[0027] Figure 11 for Figure 10 A local enlarged view of the dotted frame portion of the signal waveform;

[0028] Figure 12 FIG2 is a second structural diagram of a wireless charging system according to an embodiment.

[0029] Component number description:

[0030] Inverter circuit: 100; first resonant circuit: 200; freewheeling circuit: 300; second resonant circuit: 400. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0032] It will be understood that the terms "first," "second," and the like used herein may be used to describe various elements herein, but these elements are not limited by these terms. These terms are used solely to distinguish a first element from another element. For example, a first AC signal may be referred to as a second AC signal, and similarly, a second AC signal may be referred to as a first AC signal, without departing from the scope of this application. Both the first AC signal and the second AC signal are AC signals, but they are not the same AC signal.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of this application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0034] An embodiment of the present application provides a wireless transmitter module, which is disposed in a wireless charging device and is used to wirelessly charge a terminal. The wireless charging device and the terminal can communicate wirelessly based on the Qi protocol. The wireless charging device may be, for example, a wireless charging stand, a wireless mobile power supply (power bank), or a terminal capable of wirelessly discharging to another terminal. The above-mentioned terminals may include, but are not limited to, mobile phones, tablet computers, PDAs (Personal Digital Assistants), POS (Point of Sales), in-vehicle computers, wearable devices, electric vehicles, etc. The inventors have discovered that a large amount of loss in the wireless transmitter module comes from the inverter circuit, and the loss of the inverter circuit is mainly the conduction loss and switching loss of the parasitic switch tube. In particular, as the transmission power and switching frequency of the inverter circuit increase, the switching loss also increases significantly, thereby limiting the application of the wireless transmitter module at high power and high frequency. Therefore, the present application provides a technical solution that can effectively reduce the power consumption of the wireless transmitter module by reducing the switching loss of the inverter circuit.

[0035] Figure 1 This is one of the structural diagrams of the wireless transmission module of an embodiment, referring to Figure 1 The wireless transmitting module includes an inverter circuit 100, a first resonant circuit 200, a transmitting coil Lp and a freewheeling circuit 300.

[0036] The inverter circuit 100 includes multiple parasitic switching tubes. Parasitic switching tubes are switching tubes with parasitic capacitance and parasitic diodes. It is understandable that the parasitic capacitance and parasitic diode can be generated by the switch tube structure itself or can be additionally provided. For example, the type of switching tube can be, but is not limited to, an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOS). The structure of the above-mentioned type of switching tube can generate parasitic capacitance and parasitic diodes. For another example, the type of switching tube can also be a relay, a circuit breaker, a contactor, etc. The above-mentioned type of switching tube requires additional connection of parasitic capacitance and parasitic diodes to achieve the required circuit structure. Among them, the inverter circuit 100 can be a half-bridge inverter circuit, a full-bridge inverter circuit, or other variations of the inverter circuit, which is not limited in this embodiment, and the connection relationship between the multiple parasitic switching tubes in this embodiment can refer to the relevant technology. Specifically, the inverter circuit 100 is described here as a full-bridge inverter circuit.

[0037] Figure 2 is a circuit diagram of a full-bridge inverter circuit according to an embodiment. Figure 2The full-bridge inverter circuit includes four switching transistors, VT1, VT2, VT3, and VT4. Switches VT1 and VT2 form one bridge arm, and switches VT3 and VT4 form another bridge arm. Each switching transistor has a corresponding parasitic capacitance and parasitic diode. For example, switch VT1 has a parasitic capacitance Cds1 and a parasitic diode D1. The anode and cathode of parasitic diode D1 are determined by the type of switch VT1. In this embodiment, switch VT1 is an enhancement-mode NMOS transistor. The anode of parasitic diode D1 is connected to the source of switch VT1, and the cathode of parasitic diode D2 is connected to the drain of switch VT1. It is understood that the configuration of the other three parasitic switching transistors is similar to that of the aforementioned parasitic switching transistors and will not be further described here. The four parasitic switching transistors can be of the same or different types, and this embodiment does not impose any limitation thereto. When the four parasitic switching transistors are of the same type, analysis and control of the inverter circuit 100 are facilitated. Therefore, each embodiment of the present application is described by taking the four parasitic switch tubes of the same type as an example.

[0038] The inverter circuit 100 is used to receive a DC signal and convert the DC signal into a first AC signal, wherein the voltage and current of the first AC signal have the same phase. Specifically, the inverter circuit 100 has two working modes. Figure 2 , U in The voltage of the DC signal received by the inverter circuit 100 is represented by the connection node between the switch transistors VT1 and VT2, which is the first output terminal of the full-bridge inverter circuit. The connection node between the switch transistors VT3 and VT4 is the second output terminal of the full-bridge inverter circuit. The full-bridge inverter circuit outputs the first AC signal through both the first output terminal and the second output terminal. In this embodiment, by controlling the phase of the voltage and current of the first AC signal to be consistent, the reactive power of the connected first resonant circuit 200 can be reduced, the transmit temperature rise of the wireless transmitter module can be reduced, and signal transmission efficiency can be improved.

[0039] Continue to refer Figure 1The first resonant circuit 200 is connected to the inverter circuit 100. Specifically, the first resonant circuit 200 is connected to the inverter circuit 100 via the freewheeling circuit 300. The first resonant circuit 200 is used to resonate and compensate the first AC signal. The first resonant circuit 200 may be, but is not limited to, a series resonant circuit, a parallel resonant circuit, an LLC resonant circuit, an LCC resonant circuit, etc., and this embodiment does not impose any restrictions thereon. The transmitting coil Lp is connected to the first resonant circuit 200. The transmitting coil Lp is used to transmit an electromagnetic signal based on the first AC signal after resonance compensation. The electromagnetic signal can be understood as a periodic resonant wave with a preset power. The freewheeling circuit 300 is connected to the inverter circuit 100. The freewheeling circuit 300 is used to provide a target current to the inverter circuit 100 during the dead time of the inverter circuit 100. The target current is used to charge and discharge the parasitic capacitance of each parasitic switch tube in the inverter circuit 100. It is understandable that if two switches in the same bridge arm of the inverter circuit 100 are turned on simultaneously, a short circuit will occur in the inverter circuit 100. Therefore, a dead time is required between switching between the two operating modes to ensure that one switch in the same bridge arm is turned off before the other switch in the same bridge arm is turned on.

[0040] Figure 3 This is a current diagram of the full-bridge inverter circuit working in the first working mode, refer to Figure 3 In the first operating mode, switches VT2 and VT3 are turned on, while switches VT1 and VT4 are turned off. Current flows sequentially through switch VT3, first resonant circuit 200, transmitting coil Lp, first resonant circuit 200, and switch VT2. That is, the signal output by inverter circuit 100, after being resonantly compensated by first resonant circuit 200, flows from bottom to top through transmitting coil Lp. Figure 4 This is a current diagram of the full-bridge inverter circuit working in the second working mode, refer to Figure 4 In the second operating mode, switches VT1 and VT4 are turned on, while switches VT2 and VT3 are turned off, so that current flows sequentially through switch VT1, first resonant circuit 200, transmitting coil Lp, first resonant circuit 200, and switch VT4. That is, the signal output by inverter circuit 100, after being resonantly compensated by first resonant circuit 200, flows from top to bottom through transmitting coil Lp. Therefore, in the first and second operating modes, the directions of the signal output by inverter circuit 100 differ, thereby converting the received DC signal into a first AC signal.

[0041] Based on the above structure, the switch from the first working mode to the second working mode is used as an example for explanation. In the first working mode, since the switch tubes VT2 and VT3 are turned on and the switch tubes VT1 and VT4 are turned off, VCds2 =VC ds3 =0, VC ds1 =VC ds4 =U in . Figure 5 3 is a current diagram of the first stage when the inverter circuit 100 switches from the first working mode to the second working mode when the freewheeling circuit 300 is not provided. Figure 5 In the first stage, switching transistors VT2 and VT3 switch from the on state to the off state, while switching transistors VT1 and VT4 remain in the off state. If the output current I1 flowing through the transmitting coil Lp remains greater than zero, the inductor and other components in the first resonant circuit 200 prevent a sudden change in the output current I1, and the inverter circuit 100 can continue the current flow through the parasitic capacitance. Specifically, under the freewheeling effect, the parasitic capacitances Cds1 and Cds4 are discharged, causing the voltage across them to gradually decrease. Simultaneously, the parasitic capacitances Cds2 and Cds3 are charged, causing the voltage across them to gradually increase.

[0042] Therefore, when the inverter circuit 100 performs mode switching, it is necessary to charge and discharge each parasitic capacitor separately, which results in a certain amount of time for the output signal of the inverter circuit 100 to completely switch between positive and negative. During this period, the switching of the on and off states of the switch tube will generate certain switching losses. In other words, if the charging and discharging speed of the parasitic capacitor is accelerated, the source-drain voltage at the switching moment of the on and off states can be reduced, thereby reducing the switching loss of the switch tube. However, it is understood that if the voltage and current of the first AC signal are in phase with each other, then during the dead time of the mode switching, the output current I1 will be close to 0, resulting in insufficient current flowing through the inverter circuit 100, and thus the parasitic capacitors of the inverter circuit 100 cannot be completely charged and discharged, resulting in higher switching losses of the inverter circuit 100.

[0043] In this embodiment, by providing a freewheeling circuit 300 for outputting a target current, the current flowing through the inverter circuit 100 can be made the sum of the output current I1 and the target current. Therefore, during the dead time, even if the output current I1 is close to zero, the freewheeling circuit 300 can provide the target current to the inverter circuit 100, so that the current flowing through the inverter circuit 100 is not zero. In other words, the parasitic capacitance can be effectively charged and discharged by the target current, thereby improving the switching performance of the inverter circuit 100 and further reducing switching losses.

[0044] In one embodiment, when the parasitic capacitor Cds1 and the parasitic capacitor Cds4 are discharged until the voltage across both ends is equal to the forward voltage drop of the parasitic diode, the inverter circuit 100 may further enter the second stage of mode switching. Figure 63 is a current diagram of the second stage when the inverter circuit 100 switches from the first working mode to the second working mode when the freewheeling circuit 300 is not provided. Figure 6 In the second phase, the switches VT1, VT2, VT3, and VT4 remain in the off state. Parasitic diodes D1 and D4 conduct to provide freewheeling current, clamping the source-drain voltage of switches VT1 and VT4 to the forward voltage drop of the parasitic diodes.

[0045] It is understandable that if the forward voltage drop of the parasitic diode is close to 0, the switch tube VT1 and the switch tube VT4 can be switched from the off state to the on state. Therefore, when the switch tube switches between the on and off states, the voltage across it is already 0, and the switching loss of the switch tube can be reduced to a minimum. This on-off switching mode can be called zero voltage switching (Zero Voltage Switch, ZVS). Among them, within the dead time Td, if the parasitic capacitance of the switch tube can be fully charged and discharged, zero voltage switching can be achieved, thereby reducing the switching loss of the switch tube. Similarly, when the circuit switches from the second working mode to the first working mode, ZVS switching can also be achieved. That is, when the freewheeling circuit 300 is not set, the output current I1 flowing through the transmitting coil Lp needs to satisfy the following formula (1), which can ensure that the parasitic capacitance of the switch tube is fully charged and discharged within the dead time, thereby achieving zero voltage switching.

[0046]

[0047] Among them, T off It refers to the moment when the inverter circuit 100 switches between modes. d Refers to the length of the dead time, I 1_change Refers to the output current I1 of the inverter circuit 100 at the moment of mode switching, C ds Refers to the capacitance of each parasitic capacitor, that is, C ds1 =C ds2 =C ds3 =C ds4 =C ds Therefore, within the dead time of the inverter circuit 100, if the output current of the inverter circuit 100 is equal to the target current output by the freewheeling circuit 300, the target current must satisfy the above formula (1), thereby ensuring that the parasitic capacitance of the switch tube can be fully charged and discharged within the dead time, thereby achieving zero voltage switching.

[0048] In one embodiment, the provision of the freewheeling circuit 300 can significantly accelerate the charging and discharging speed of the parasitic capacitance. Accordingly, since the parasitic capacitance can be charged and discharged in a relatively short period of time, a long dead time is not required. This further increases the switching frequency of the inverter circuit 100 and reduces the inductance and volume of the transmitting coil Lp.

[0049] In one embodiment, the freewheeling circuit 300 includes a freewheeling inductor. Figure 7 This is a second structural diagram of a signal transmission module according to an embodiment, referring to Figure 7 , the two ends of the freewheeling inductor Lc are respectively connected to the first output terminal and the second output terminal of the inverter circuit 100 in a one-to-one correspondence. Specifically, in order to ensure that the wireless transmission module is in the most efficient resonant state, a parallel freewheeling inductor Lc can be set to ensure that the current flowing through the inverter circuit 100 during mode switching satisfies formula (1). Figure 7 As shown, when the mode is switched, since the first resonant circuit 200 operates in a resonant state, the current flowing through the inverter circuit 100 is equal to the current output by the freewheeling inductor Lc, that is, the target current. Substituting the freewheeling inductor Lc into the above formula (1) can obtain the following formula (2).

[0050]

[0051] Therefore, by connecting a freewheeling inductor Lc in parallel between the inverter circuit 100 and the first resonant circuit 200, and ensuring that the value of the freewheeling inductor Lc satisfies the above equation, the freewheeling inductor Lc can provide a sufficiently large target current to the inverter circuit 100 during mode switching, thereby completely charging and discharging the parasitic capacitance within the dead time, and conducting the parasitic diode to achieve freewheeling clamping, thereby achieving zero voltage switching. Furthermore, since the freewheeling inductor Lc is connected in parallel to the first resonant circuit 200, it can also prevent the freewheeling inductor Lc from affecting the resonant performance of the first resonant circuit 200.

[0052] Figure 8 This is a third structural diagram of a wireless transmission module according to an embodiment, referring to Figure 8In one embodiment, the inverter circuit 100 is a half-bridge inverter circuit. The half-bridge inverter circuit includes two switching transistors VT3 and VT4, and two capacitors C1 and C2. Switching transistors VT3 and VT4 form a bridge arm. The connection node between capacitors C1 and C2 is the first output terminal of the half-bridge inverter circuit, and the connection node between switching transistors VT3 and VT4 is the second output terminal of the half-bridge inverter circuit. It is understood that the two switching transistors in the half-bridge inverter circuit each have corresponding parasitic capacitances and parasitic diodes. The configuration of the switching transistors, parasitic capacitances, and parasitic diodes is similar to that of a full-bridge inverter circuit and will not be further described here. In the first operating mode, switching transistor VT3 is turned on and switching transistor VT4 is turned off, so that current flows sequentially through switching transistor VT3, the first resonant circuit 200, the transmitting coil Lp, the first resonant circuit 200, and capacitor C2. That is, the signal output by the inverter circuit 100, after being resonantly compensated by the first resonant circuit 200, flows from bottom to top through the transmitting coil Lp. In the second operating mode, switch VT4 is turned on and switch VT3 is turned off, causing current to flow sequentially through capacitor C1, first resonant circuit 200, transmitting coil Lp, first resonant circuit 200, and switch VT4. That is, the signal output by inverter circuit 100, after being resonantly compensated by first resonant circuit 200, flows from top to bottom through transmitting coil Lp. Therefore, in the first and second operating modes, the direction of the signal output by inverter circuit 100 differs, thereby converting the received DC signal into a first AC signal.

[0053] Correspondingly, the freewheeling circuit 300 also includes a filter capacitor Cc. One end of the filter capacitor Cc is connected to the first output end of the half-bridge inverter circuit, and the other end of the filter capacitor Cc is connected to one end of the freewheeling inductor Lc. The other end of the freewheeling inductor Lc is connected to the second output end of the half-bridge inverter circuit. In this embodiment, by connecting the filter capacitor Cc in series with the first output end of the inverter circuit 100, the DC component in the first AC signal output by the half-bridge inverter circuit can be filtered out, thereby avoiding a DC short circuit of the freewheeling inductor Lc, and further avoiding damage to the wireless transmitter module caused by the instantaneous large current generated by the short circuit.

[0054] In one embodiment, the inverter circuit 100 includes at least one bridge arm, each of which includes two parasitic switching transistors. Specifically, when the inverter circuit 100 is a full-bridge inverter circuit, the inverter circuit 100 includes one bridge arm; when the inverter circuit 100 is a half-bridge inverter circuit, the inverter circuit 100 includes two bridge arms. The two parasitic switching transistors in the same bridge arm are configured to conduct in different operating modes, and the two parasitic switching transistors in the same bridge arm have different conduction duty cycles. Specifically, taking a half-bridge inverter circuit as an example, switch VT3 and switch VT4 are the two parasitic switching transistors in the same bridge arm. That is, the conduction duty cycle of switch VT3 and switch VT4 is 50%. Based on the above control method, the inverter circuit 100 can also be referred to as an asymmetric inverter circuit 100. It is understood that if the on-duty cycles of the switches VT3 and VT4 are different, the signal amplitude of the positive half-cycle of the first AC signal output by the inverter circuit 100 will also be different from the signal amplitude of the negative half-cycle, thereby changing the power of the signal transmitted by the transmitting coil Lp, thereby achieving small-range power modulation and improving the flexibility of the wireless transmitting module when transmitting signals. It is understood that in some embodiments, the inverter circuit 100 can also be a symmetrical inverter circuit 100, that is, the on-duty cycles of the two parasitic switches in the same bridge arm are the same, and the on-duty cycles of the switches VT3 and VT4 are both 50%.

[0055] Figure 9 This is a schematic diagram of the structure of a wireless charging system according to an embodiment. Figure 9 In one embodiment, the first resonant circuit 200 includes a resonant inductor Lm, a first resonant capacitor Cp, a second resonant capacitor Cm and a first resonant resistor Rp. It is understandable that the inverter circuit 100 can also be of any type, and this embodiment does not limit it. For ease of explanation, this embodiment uses the fundamental wave analysis method to equate the output of the inverter circuit 100 to a sinusoidal excitation source U1, and takes the terminal as a series resonant circuit as an example for exemplary calculation, and equates the load circuit to R ac .

[0056] One end of the resonant inductor Lm is connected to the first output terminal of the inverter circuit 100. One end of the first resonant capacitor Cp is connected to the other end of the resonant inductor Lm, and the other end of the first resonant capacitor Cp is connected to one end of the transmitting coil Lp. One end of the second resonant capacitor Cm is connected to the resonant inductor Lm for connection to one end of the first resonant capacitor Cp, and the other end of the second resonant capacitor Cm is connected to the second output terminal of the inverter circuit 100. One end of the first resonant resistor Rp is connected to the second output terminal of the inverter circuit 100, and the other end of the first resonant resistor Rp is connected to the other end of the transmitting coil Lp. The first resonant circuit 200 of this embodiment can be referred to as an LCC resonant topology. By properly selecting parameters, the LCC resonant topology can operate in a constant voltage magnetic resonance state, thereby significantly reducing reactive power, resonant cavity current peak, and parasitic losses.

[0057] In one embodiment, the values of the resonant inductor Lm and the second resonant capacitor Cm are determined according to the inductance of the first resonant capacitor Cp, the transmitting coil Lp, and the resonant frequency. Specifically, the voltage U1 received by the first resonant circuit 200 satisfies the following equation (3), and the equivalent resistance R of the load circuit is ac The formula (4) is as follows. in It refers to the voltage of the DC signal input to the inverter circuit 100.

[0058]

[0059]

[0060] Based on the above voltage U1 and the equivalent resistance R of the load circuit ac ,according to Figure 9 The circuit structure shown, the mutual inductance principle and Kirchhoff's law can be used to obtain the following equations (5) and (6).

[0061]

[0062]

[0063] Among them, L m is the resonant inductor, C P is the first resonant capacitor, C m is the second resonant capacitor, L P is the inductance of the transmitting coil Lp, ω is the resonant frequency, R P is the first resonant resistance, R S is the parasitic resistance on the terminal side (also called the second resonant resistance), C s is the third resonant capacitor, L sis the inductance of the receiving coil.

[0064] The following equation (7) can be obtained from the above equations (5) and (6).

[0065]

[0066] According to the above formula (7), the output to the load circuit R ac The voltage satisfies the following equation (8).

[0067]

[0068] Therefore, in order to ensure that the output voltage U2 on the terminal side does not change with the load R ac If the resonant inductor Lm and the first resonant capacitor Cp are changed, they need to work in a resonant state, that is, the following formula (9) is obtained, that is, the first resonant circuit 200 and the transmitting coil Lp need to satisfy the formula (9).

[0069] 1-ω 2 L m C m =0 (9)

[0070] Furthermore, the parasitic resistance R can be optimized by optimizing the design of the transmitting coil Lp and the receiving coil Ls, optimizing the routing design, and optimizing the selection of key components. S Much smaller than the load resistance R ac , at this time the load voltage Therefore, when the coupling position of the transmitting coil Lp and the receiving coil Ls remains unchanged, the mutual inductance coefficient M remains unchanged, and the wireless transmitting module has the characteristic of constant voltage output. That is, the output voltage of the wireless transmitting module does not change with changes in the load circuit, thereby ensuring the stability and controllability of the wireless transmitting module. When the wireless transmitting module operates in the constant voltage output state, the input impedance can be obtained to satisfy the following formula (10).

[0071]

[0072] It can be understood that when working in the resonant state, the input impedance is purely resistive, that is, the imaginary part of the input impedance is 0, and the following formula (11) can be obtained.

[0073]

[0074] In summary, when the parameter design of the first resonant circuit 200 satisfies the above equations (9) and (11), the wireless transmission module operates in a constant voltage magnetic resonance state. In this embodiment, by designing the parameters of the resonant inductor Lm and the first resonant capacitor Cp, the wireless transmission module can be operated in a constant voltage magnetic resonance state, thereby reducing the reactive power of the wireless transmission module and lowering the loss caused by parasitic resistance.

[0075] In one embodiment, the inverter circuit in the wireless transmitter module is a full-bridge inverter circuit, the first resonant circuit is an LCC resonant topology, and the freewheeling circuit includes a freewheeling inductor Lc. Based on the structure of the wireless transmitter module, simulation can be performed to obtain Figure 10 The simulation results are shown in Figure 2. Figure 10 This embodiment simulates the source-drain voltage V(ds) of the switch tube VT4, the driving voltage V(gs) of the switch tube VT4, the output voltage V(sw1, sw2) of the inverter circuit, and the output current I(sw) of the inverter circuit during operation of the inverter circuit. Figure 10 The signal waveforms in one complete cycle of the inverter circuit and a partial time adjacent to the complete cycle are shown. Figure 11 for Figure 10 The dotted box portion of the signal waveform is a partial enlarged view, specifically, Figure 11 The signal waveform of the process of switching the inverter circuit from the first working mode to the second working mode is shown. Figure 10 and Figure 11 During the mode switching process, the source-drain voltage V(ds) gradually decreases, indicating that the parasitic capacitor Cds4 is being discharged. After a period of discharge, the source-drain voltage V(ds) of the switch tube VT4 is clamped to the forward voltage drop of the parasitic diode, that is, it is expressed as Figure 11 The source-drain voltage V(ds) is maintained at a minimum voltage. Furthermore, when the parasitic capacitor Cds4 begins to discharge, the output current I(sw) is not zero, indicating that the freewheeling inductor Lc can provide sufficient freewheeling current to charge and discharge the parasitic capacitor in the inverter circuit during mode switching. Furthermore, only after the source-drain voltage V(ds) of the switch tube VT4 is clamped to the forward voltage drop of the parasitic diode does the drive voltage V(gs) change to the threshold voltage of the switch tube VT4, thereby controlling the switch tube VT4 to conduct and realize the ZVS switch function. Throughout the mode switching process, the output voltage V(sw1, sw2) gradually achieves phase reversal, meaning that the inverter circuit effectively converts the received DC signal into a first AC signal.

[0076] In one embodiment, the wireless transmission module may further include a DC power supply and a DC-DC converter connected thereto, the DC-DC converter further being connected to the inverter circuit. The DC-CDC converter is configured to step up or step down the DC signal outputted by the DC power supply to obtain a DC signal having a target voltage, and transmit the DC signal having the target voltage to the inverter circuit.

[0077] An embodiment of the present application also provides a wireless charging device, comprising a controller and a wireless transmission module as described above. The controller is connected to the inverter circuit of the wireless transmission module and is used to control the inverter circuit to alternately switch operating modes so that the inverter circuit converts the received DC signal into the first AC signal. In this embodiment, based on the wireless transmission module, the losses in the wireless charging device can be reduced, thereby reducing the power consumption of the wireless charging device.

[0078] Figure 12 This is a second structural diagram of a wireless charging system according to an embodiment. Figure 12 The wireless charging system includes a terminal and a wireless charging device as described above. The terminal includes a receiving coil Ls and a second resonant circuit 400. The receiving coil Ls is electromagnetically coupled to the transmitting coil Lp of the wireless charging device for receiving the electromagnetic signal. The second resonant circuit 400 is connected to the receiving coil Ls for generating a second AC signal based on the electromagnetic signal, and the second AC signal is used to power the load circuit of the terminal. Specifically, the load circuit includes a rectifier and filter circuit and a load. In the above embodiment of the present application, the entire load circuit is equivalent to a load impedance Zac. The load impedance Zac can be simplified to be equivalent to a pure resistive load, but depending on the specific application scenario, the load impedance Zac can also be a reactive load, that is, including at least one of a capacitive load and an inductive load. It is understandable that the types of the first resonant circuit 200 and the second resonant circuit 400 can be the same or different, and this embodiment does not limit this. In this embodiment, based on the above wireless charging device, the loss during the charging process can be greatly reduced, thereby providing a wireless charging system with high charging efficiency.

[0079] In one embodiment, continue with reference to Figure 9The second resonant circuit 400 includes a third resonant capacitor Cs and a second resonant resistor Rs. One end of the third resonant capacitor Cs is connected to one end of the receiving coil Ls, and the other end of the third resonant capacitor Cs is connected to one end of the load circuit. One end of the second resonant resistor Rs is connected to the other end of the receiving coil Ls, and the other end of the second resonant resistor Rs is connected to the other end of the load circuit. In this embodiment, the second resonant circuit 400 can also be referred to as a series resonant topology. When the first resonant circuit 200 is an LCC resonant topology, the wireless charging system can be referred to as an LCC-s topology. The LCC-s topology has a relatively simple circuit structure and better resonant performance.

[0080] In one embodiment, the second resonant circuit 400 also operates in a resonant state. Therefore, the second resonant circuit 400 satisfies the following equation (12).

[0081] 1-ω 2 L s C s =0 (12)

[0082] Among them, C s is the third resonant capacitor, L s is the inductance of the receiving coil, and ω is the resonant frequency.

[0083] The present application also provides a circuit control method, which can be applied to the wireless transmission module provided in the above embodiment of the present application. Figure 1 The circuit control method includes: controlling the alternating inverter circuit 100 to operate in a first operating mode and a second operating mode, so that the inverter circuit 100 converts a DC signal into a first AC signal and causes the transmitting coil Lp to transmit an electromagnetic signal based on the first AC signal after resonance compensation; presetting a dead time between switching between the first and second operating modes, so that the freewheeling circuit 300 provides a target current to the inverter circuit 100 during the dead time of the inverter circuit 100, the target current being used to charge and discharge the parasitic capacitance of each parasitic switch in the inverter circuit 100. When the inverter circuit 100 is in the first operating mode, some of the switches in the inverter circuit 100 are turned on; when the inverter circuit 100 is in the second operating mode, the remaining switches in the inverter circuit 100 are turned on. The voltage of the first AC signal is in phase with the current. The implementation principle and technical effects of the circuit control method are similar and will not be further described here.

[0084] In one embodiment, an electronic device is provided, which includes the wireless transmission module provided in the above embodiment of the present application. Its implementation principle and technical effects are similar and will not be repeated here.

[0085] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the technical solution in the above-mentioned circuit control method embodiment of the present application is implemented. The implementation principle and technical effect are similar and will not be repeated here.

[0086] In one embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the technical solution in the above-mentioned circuit control method embodiment of the present application is implemented. The implementation principle and technical effect are similar and will not be repeated here.

[0087] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. For purposes of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The processors involved in the various embodiments provided herein may be general-purpose processors, central processing units (CPUs), graphics processors (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like, without limitation thereto.

[0088] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] The above-described embodiments merely represent several implementation methods of the embodiments of the present application. The descriptions thereof are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the concept of the embodiments of the present application, and these all fall within the scope of protection of the embodiments of the present application. Therefore, the scope of protection of the patent of the embodiments of the present application shall be based on the appended claims.

Claims

1. A wireless transmission module, characterized in that: include: An inverter circuit, comprising a plurality of parasitic switching tubes, the inverter circuit having a first output terminal and a second output terminal, for receiving a DC signal and converting the DC signal into a first AC signal, outputting the first AC signal through the first output terminal and the second output terminal, wherein the voltage and current of the first AC signal are in phase with each other; a first resonant circuit, connected to the inverter circuit, for performing resonance compensation on the first AC signal; a transmitting coil, connected to the first resonant circuit, and configured to transmit an electromagnetic signal according to the first AC signal after resonance compensation; a freewheeling circuit connected to the inverter circuit and configured to provide a target current to the inverter circuit during a dead time of the inverter circuit, such that the current flowing through the inverter circuit is the sum of the output current of the transmitting coil and the target current, wherein the target current is used to charge and discharge the parasitic capacitance of each parasitic switch tube in the inverter circuit; the freewheeling circuit includes a freewheeling inductor, wherein two ends of the freewheeling inductor are respectively connected to the first output terminal and the second output terminal of the inverter circuit; Wherein, within the dead time of the inverter circuit, the output current of the inverter circuit is equal to the target current output by the freewheeling circuit.

2. The wireless transmission module according to claim 1, wherein: The inverter circuit is a half-bridge inverter circuit, and the freewheeling circuit further includes: a filter capacitor, one end of the filter capacitor being connected to the first output end of the half-bridge inverter circuit, and the other end of the filter capacitor being connected to one end of the freewheeling inductor; The other end of the freewheeling inductor is connected to the second output end of the half-bridge inverter circuit.

3. The wireless transmission module according to any one of claims 1 to 2, characterized in that: The inverter circuit includes at least one bridge arm, and each bridge arm includes two parasitic switch tubes; The two parasitic switch tubes in the same bridge arm are respectively used to be turned on in different working modes, and the conduction duty cycles of the two parasitic switch tubes in the same bridge arm are different.

4. The wireless transmission module according to any one of claims 1 to 2, characterized in that: The first resonant circuit comprises: a resonant inductor, one end of which is connected to the first output end of the inverter circuit; a first resonant capacitor, one end of the first resonant capacitor being connected to the other end of the resonant inductor, and the other end of the first resonant capacitor being connected to one end of the transmitting coil; a second resonant capacitor, one end of the second resonant capacitor being connected to the end of the resonant inductor used for connecting to the first resonant capacitor, and the other end of the second resonant capacitor being connected to the second output end of the inverter circuit; A first resonant resistor, one end of the first resonant resistor is connected to the second output end of the inverter circuit, and the other end of the first resonant resistor is connected to the other end of the transmitting coil.

5. The wireless transmission module according to claim 4, wherein: The values of the resonant inductor and the second resonant capacitor are determined according to the first resonant capacitor, the inductance of the transmitting coil, and the resonant frequency.

6. The wireless transmission module according to claim 5, characterized in that: The first resonant circuit and the transmitting coil satisfy: 1-h 2 L m C m =0 Among them, L m is the resonant inductor, C P is the first resonant capacitor, C m is the second resonant capacitor, L P is the inductance of the transmitting coil, and ω is the resonant frequency.

7. A wireless charging device, characterized in that: include: The wireless transmission module according to any one of claims 1 to 6; The controller is connected to the inverter circuit of the wireless transmission module and is used to control the inverter circuit to alternately switch working modes so that the inverter circuit converts the received DC signal into the first AC signal.

8. A wireless charging system, characterized in that: The wireless charging device comprises a terminal and the wireless charging device according to claim 7, wherein the terminal comprises: a receiving coil, electromagnetically coupled to the transmitting coil of the wireless charging device, for receiving the electromagnetic signal; The second resonant circuit is connected to the receiving coil and is used to generate a second AC signal according to the electromagnetic signal, and the second AC signal is used to power a load circuit of the terminal.

9. The wireless charging system according to claim 8, wherein: The second resonant circuit comprises: a third resonant capacitor, one end of the third resonant capacitor being connected to one end of the receiving coil, and the other end of the third resonant capacitor being connected to one end of the load circuit; A second resonant resistor, one end of the second resonant resistor is connected to the other end of the receiving coil, and the other end of the second resonant resistor is connected to the other end of the load circuit.

10. The wireless charging system according to claim 9, wherein: The second resonant circuit satisfies: 1-h 2 L s C s =0 Among them, C s is the third resonant capacitor, L s is the inductance of the receiving coil, and ω is the resonant frequency.

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