A constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system and method

Abstract

The present invention discloses an S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching, comprising a power supply circuit, a resonant coupling circuit, a trigger circuit, and a battery charging circuit. The resonant coupling circuit includes a transmitter and a receiver. When the transmitter and receiver adopt a series-series compensation topology, the resonant coupling circuit operates in a constant current mode, providing a constant charging current for the battery charging circuit. When the transmitter and receiver adopt a CLC-series topology, the resonant coupling circuit operates in a constant voltage mode, providing a constant charging voltage for the battery charging circuit. The resonant coupling circuit provides a trigger condition for the trigger circuit, and the trigger circuit output voltage serves as a trigger signal for switching the resonant coupling circuit between CC mode and CV mode. The power supply circuit provides electrical energy for the entire system. The present invention provides a more stable system structure, simplifies control costs, improves charging efficiency, and has excellent economic and practical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and more particularly to an S / CLC-S type wireless charging system and method with constant current and constant voltage self-monitoring switching. Background Art

[0002] With the development of modern power electronics, wireless charging, as a contactless energy transfer technology, has attracted widespread attention in fields such as electric vehicles, drones, medical devices, and portable power electronics due to its safety and convenience. Lithium-ion batteries, as rechargeable green energy storage components, have naturally become a key research topic for wireless charging due to their increasing demand in power facilities such as mobile devices and electric vehicles.

[0003] Lithium-ion battery charging methods can generally be categorized into constant current (CC) and constant voltage (CV) based on their charging characteristics. During the CC process, the current is maintained at a high level to quickly top up the battery. The battery's charge voltage is low in the initial stages, but gradually increases as the charging process progresses. This can significantly impact the battery's internal electrodes in the later stages of charging, reducing battery life. The CV process provides a constant charge voltage for the lithium-ion battery. The charge current is high in the initial stages, but gradually decreases as the charging process progresses, resulting in a very low and slowly changing charge current in the later stages. To extend the lifespan of lithium-ion batteries while ensuring full battery replenishment, a combination of constant current and constant voltage charging is typically used. During the initial charging phase, the battery is typically charged using the manufacturer's specified CC mode. During this process, the battery charge voltage rises rapidly. Once the charge voltage reaches the maximum voltage allowed by the lithium-ion battery, the battery switches to CV mode, where the charge current rapidly decreases until it reaches approximately one-tenth of the CC mode current, concluding the charging process. Throughout the charging process, the battery's equivalent resistance gradually increases, resulting in significant fluctuations. Designing a WPT system that can maintain both CC and CV charging capabilities under varying load conditions presents a significant challenge.

[0004] In the past few years, some scholars have proposed control methods for implementing CC and CV charging modes in WPT systems, mainly including phase shifting modulation (PSW) and frequency conversion control (FCC). PSW technology controls the phase angle of the inverter to ensure that the charging voltage and current remain constant under load changes. However, when there are large load changes, this technology cannot meet the requirements of zero voltage switching (ZVS) operation, and the inverter generates large conduction losses. FCC technology may affect system stability due to the frequency division phenomenon and cannot achieve zero phase angle operation (ZPA), resulting in large reactive power losses. Both have a significant impact on charging efficiency. Although excellent CC and CV output characteristics can be achieved, it increases system complexity. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide an S / CLC-S type wireless charging system and method with constant current and constant voltage self-monitoring switching, which realizes CC / CV mode adaptive switching by optimizing the design of topology circuit (S / CLC-S) and parameter configuration method.

[0006] Technical solution: The present invention provides a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system, which includes a power supply circuit, a resonant coupling circuit, a trigger circuit and a battery charging circuit. The resonant coupling circuit includes a transmitter and a receiver. When the transmitter and the receiver are in a series-series (SS) compensation topology, the resonant coupling circuit operates in a constant current (CC) mode to provide a constant charging current for the battery charging circuit; when the transmitter and the receiver are in a CLC-series (CLC-S) topology, the resonant coupling circuit operates in a constant voltage (CV) mode to provide a constant charging voltage for the battery charging circuit; the resonant coupling circuit provides a trigger condition for the trigger circuit, and the output voltage of the trigger circuit is used as a switching trigger signal for the resonant coupling circuit to operate in CC mode and CV mode; the power supply circuit provides electrical energy for the entire system.

[0007] Optionally, the transmitting end includes a transmitting coil L T , a first compensation inductor L1, a second compensation inductor L2, a first compensation capacitor C1, a second compensation capacitor C2, a first signal relay KV1 and a second signal relay KV2; the receiving end includes a receiving coil L R and the third compensation capacitor C3, where the transmitting coil L T With the receiving coil L R Mutual inductive coupling;

[0008] In CC mode, the first signal relay KV1 and the second signal relay KV2 are disconnected, and the first compensation inductor L1, the first compensation capacitor C1, the second compensation capacitor C2 and the transmitting coil L T Series connection, receiving coil L R connected in series with the third compensation capacitor C3 to form a series-series (SS) compensation topology;

[0009] In CV mode, the first signal relay KV1 and the second signal relay KV2 are turned on, and the second compensation capacitor C2 and the transmitting coil L T The first compensation inductor C1 is connected in series with the receiving coil L2. R It is connected in series with the third compensation capacitor C3 to form a CLC-series (CLC-S) topology.

[0010] Optionally, the trigger circuit is connected in parallel across the second compensation capacitor C2, and the voltage change of the second compensation capacitor C2 is a trigger condition of the trigger circuit; the trigger circuit output is used as a trigger signal for the first signal relay KV1 and the second signal relay KV2.

[0011] Optionally, the trigger circuit includes a rectifier voltage divider circuit and a hysteresis circuit. The rectifier voltage divider circuit converts the input trigger signal into AC / DC and steps down the voltage before inputting it into the hysteresis circuit. The output voltage of the hysteresis circuit serves as a switching signal for the working mode of the resonant coupling circuit.

[0012] Optionally, the rectifier voltage divider circuit includes an AC / DC voltage conversion circuit, a first filter capacitor C f , the first voltage divider resistor R Div1 and the second voltage divider resistor R Div2 , the first filter capacitor C f In parallel with the AC / DC converter circuit, the first voltage divider resistor R Div1 With the second voltage divider resistor R Div2 After connecting in series with the first compensation capacitor C f Connect in parallel, the second voltage divider resistor R Div2 The voltage divider is input to the hysteresis circuit.

[0013] Optionally, a hysteresis circuit and a second voltage divider resistor R Div2 Connected in parallel to determine the second voltage divider resistor R Div2 Whether the voltage across the terminals exceeds the reference voltage V REF , to control the output state of the hysteresis circuit; when the second voltage divider resistor R Div2 The voltage across the terminals exceeds the reference voltage V REF When the hysteresis circuit outputs a high level, the first signal relay KV1 and the second signal relay KV2 in the resonant coupling circuit are actuated to switch the state of the resonant coupling circuit; when the second voltage divider resistor R Div2The voltage across the terminals does not exceed the reference voltage V REF When , the hysteresis circuit outputs a low level, the first signal relay KV1 and the second signal relay KV2 in the resonant coupling circuit do not trigger an action, and the state of the resonant coupling circuit does not switch.

[0014] Optionally, the resonance condition of the resonant coupling circuit is:

[0015]

[0016] Where ω represents the system operating angular frequency, L1 is the first compensation inductor at the transmitter, L2 is the second compensation inductor at the transmitter, C1 is the first compensation capacitor at the transmitter, C2 is the second compensation capacitor at the transmitter, L T For the transmitting coil.

[0017] Optionally, the parameter configuration scheme of each component in the resonant coupling circuit is:

[0018]

[0019] Where ω represents the system operating angular frequency, L1 is the first compensation inductor at the transmitter, L2 is the second compensation inductor at the transmitter, C1 is the first compensation capacitor at the transmitter, C2 is the second compensation capacitor at the transmitter, L T is the transmitting coil, R switch is the equivalent resistance value corresponding to the battery charging circuit switching from CC mode to CV mode, and M is the mutual inductance between the transmitting coil and the receiving coil.

[0020] Optionally, the triggering condition of the trigger circuit is:

[0021]

[0022] Among them, U do is the switching voltage, V i is the AC input voltage of the system, L T is the self-inductance of the transmitting coil, R switch is the equivalent resistance value corresponding to the battery charging circuit switching from CC mode to CV mode, ω represents the system operating angular frequency, M is the mutual inductance between the transmitting coil and the receiving coil; U Drive is the driving voltage of the hysteresis circuit, R Div1 is the first voltage divider resistor, R Div2 The second voltage divider resistor R Div2 ;

[0023] When the voltage input from the resonant coupling circuit to the trigger circuit reaches U do When the second voltage divider resistor R Div2 The voltage across the two ends rises to the driving voltage U of the hysteresis circuit Drive, triggering the hysteresis circuit to output a high-level voltage, realizing the switching of the working mode of the resonant coupling circuit.

[0024] The present invention provides a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging method, which adopts the above system and includes the following steps:

[0025] The system is powered on and initialized, entering the working state. The resonant coupling circuit adopts the SS compensation topology and is in CC mode.

[0026] As the CC mode charging process continues, the charging current of the battery charging circuit remains unchanged, while the equivalent internal resistance gradually increases, and the charging voltage of the battery charging circuit increases accordingly. Due to the circuit characteristics, the voltage input from the transmitter to the trigger circuit also increases accordingly.

[0027] When the charging voltage of the battery charging circuit reaches the maximum charging voltage U B When the voltage input from the transmitter to the trigger circuit rises to the switching voltage U do , and then the hysteresis circuit driving voltage also increases to the hysteresis circuit reference value V REF , triggering the hysteresis circuit to switch the output state and output a high level V switch , control the resonant coupling circuit to switch to CLC-S compensation topology, and then to CV mode;

[0028] As the equivalent resistance of the battery charging circuit continues to increase, the charging voltage is maintained at U B The charging current of the battery charging circuit continues to decrease. When it drops to one tenth of the CC mode charging current, charging stops.

[0029] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0030] (1) The present invention eliminates the communication link and relies on the circuit's own characteristics to achieve the switching of circuit topology (S / CLC-S), thereby realizing the CC / CV mode, simplifying the control process, and reducing the control cost;

[0031] (2) Compared with the traditional multi-frequency control strategy, the frequency of the present invention remains unchanged, the system is more stable, and the switch conduction loss is smaller;

[0032] (3) The present invention provides a hysteresis circuit, which has a clamping effect and ensures stable changes in the transition section;

[0033] (4) The present invention satisfies ZPA operation, has lower reactive power and higher charging efficiency;

[0034] (5) The present invention has a simple structure, low component cost, a perfect charging strategy, a clear parameter configuration method, and uses a wireless charging system to transfer energy between the power supply equipment and the power-consuming equipment through an electromagnetic field without the need for direct physical contact. It can effectively deal with the impact of severe weather, humid environments, etc. on the charging of drones, and has high power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a system equivalent circuit diagram of a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system provided by an embodiment of the present invention; wherein (a) is the overall circuit structure, (b) is the CC mode equivalent circuit diagram, and (c) is the CV mode equivalent circuit diagram;

[0036] Figure 2 A simplified circuit diagram of a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system provided by an embodiment of the present invention; (a) is a simplified circuit diagram of the CC mode, and (b) is a simplified circuit diagram of the CV mode;

[0037] Figure 3 A flowchart of a charging method for a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system provided by an embodiment of the present invention;

[0038] Figure 4 These are simulation curves of G(ωCC), E(ωCV), and the corresponding input impedance angle under different load conditions provided by an embodiment of the present invention. (a) shows how the transconductance gain changes with system frequency in CC mode, (b) shows how the voltage gain changes with system frequency in CV mode, (c) shows how the input impedance angle changes with system frequency in CC mode, and (d) shows how the input impedance angle changes with system frequency in CV mode.

[0039] Figure 5 This is a diagram of an experimental prototype of an S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching provided by an embodiment of the present invention;

[0040] Figure 6 Oscilloscope waveforms under different loads in the experiment provided by the embodiment of the present invention;

[0041] Figure 7 Continuous waveform diagrams under different load conditions in the experiments provided by the embodiments of the present invention;

[0042] Figure 8 This is a system CC / CV charging curve and charging efficiency change curve of a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The drawings are for illustrative purposes only and are not to be construed as limiting this patent. To better illustrate the embodiments, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of actual products. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0044] To avoid the shortcomings of PSW and FCC, the present invention provides a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system, including a power supply circuit, a resonant coupling circuit, a trigger circuit and a battery charging circuit. The resonant coupling circuit includes a transmitter and a receiver. When the transmitter and the receiver are in a series-series (SS) compensation topology, the resonant coupling circuit operates in a constant current (CC) mode to provide a constant charging current for the battery charging circuit; when the transmitter and the receiver are in a CLC-series (CLC-S) topology, the resonant coupling circuit operates in a constant voltage (CV) mode to provide a constant charging voltage for the battery charging circuit; the resonant coupling circuit provides a trigger condition for the trigger circuit, and the output voltage of the trigger circuit is used as a switching trigger signal for the resonant coupling circuit to operate in CC mode and CV mode; the power supply circuit provides power for the entire system. Compared with traditional control strategies such as frequency control and communication control, the present invention eliminates the switching of multiple frequencies, making the system structure more stable. At the same time, it relies on the system's own circuit characteristics to achieve adaptive topology switching, eliminating complex communication control strategies and greatly simplifying control costs. In addition, the present invention can achieve zero phase angle (ZPA) operation, which reduces the reactive loss of the system and improves charging efficiency. This method can solve the inherent problems of traditional constant current and constant voltage wireless charging systems, such as complex switching, low efficiency, high control cost, and high maintenance cost. It can achieve precise switching of constant current and constant voltage charging modes while maintaining a high level of transmission efficiency. In the field of wireless charging involving lithium battery charging, such as electric vehicles, drones, and portable power electronic equipment, the present invention has clear judgment logic, stable switching control method, efficient charging strategy, and high charging efficiency, and has good economy and practicality.

[0045] Example 1:

[0046] like Figure 1 As shown in (a), (b), and (c), the present invention is a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system, including: a power supply circuit, a resonant coupling circuit, a trigger circuit, and a battery charging circuit.

[0047] The power supply circuit includes a DC power supply, a step-down drive circuit, an inverter circuit and a PWM drive circuit; the resonant coupling circuit includes a transmitter and a receiver, and the transmitter includes a transmitting coil L T, a first compensation inductor L1, a second compensation inductor L2, a first compensation capacitor C1, a second compensation capacitor C2, a first signal relay KV1 and a second signal relay KV2; the receiving end includes a receiving coil L R and the third compensation capacitor C3, where the transmitting coil L T With the receiving coil L R Mutual inductance coupling; the trigger circuit includes a rectifier voltage divider circuit and a hysteresis circuit. The rectifier voltage divider circuit converts the input voltage signal into AC / DC and divides the voltage before inputting it into the hysteresis circuit. The hysteresis circuit outputs a voltage as a switching signal for the working mode of the resonant coupling circuit; the rectifier voltage divider circuit includes an AC / DC converter circuit, a first filter capacitor C f , the first voltage divider resistor R Div1 and the second voltage divider resistor R Div2 The hysteresis circuit includes a first hysteresis circuit resistor R hc1 , the second hysteresis circuit resistor R hc2 and hysteresis comparator; the battery charging circuit includes a rectifier circuit D1-D4, a second filter capacitor C and a battery charging circuit equivalent resistor R BAT .

[0048] In the power supply circuit, a DC power supply is connected in parallel with a step-down drive circuit to generate a low-voltage drive voltage to drive a hysteresis comparator. The DC power supply is connected in parallel with a first end of an inverter circuit, and a second end of the inverter circuit is connected to a resonant coupling circuit as an AC output of the power supply circuit. In this embodiment, the inverter circuit is a high-frequency full-bridge inverter circuit including four switching tubes S1, S2, S3, and S4. The step-down drive circuit adopts a DC / DC circuit.

[0049] The resonant coupling circuit includes two output modes: constant current (CC) and constant voltage (CV). In CC mode, the first signal relay KV1 and the second signal relay KV2 are disconnected, and the first compensation inductor L1, the first compensation capacitor C1, the second compensation capacitor C2 and the transmitting coil L T Series connection, receiving coil L R The first signal relay KV1 and the second signal relay KV2 are connected in series with the third compensation capacitor C3 to form a series-series (SS) compensation topology to provide a constant charging current for the battery charging circuit. In CV mode, the first signal relay KV1 and the second signal relay KV2 are turned on, and the second compensation capacitor C2 and the transmitting coil L T The first compensation inductor C1 is connected in series with the receiving coil L2. R Connected in series with the third compensation capacitor C3 to form a CLC-series (CLC-S) topology, providing a constant charging voltage for the battery charging circuit;

[0050] In order to reduce reactive power and improve charging efficiency, the system needs to achieve zero phase angle (ZPA) operation. Figure 1 The system equivalent circuit shown in the figure is simplified, and the simplified equivalent circuit is as follows Figure 2 As shown in (a) and (b), I1-I5 represent the current flowing through each mesh respectively. According to Kirchhoff's law, the following expression can be obtained:

[0051]

[0052] Among them, V i is the system's AC input voltage, CC Mode and CV Mode Respectively Figure 2 The CC mode and CV mode shown in (a) and (b) are X T =X L1 +X C1 +X C2 +X LT +R1, X R =X LR +X C3 +R+R2,X VCL =X C1 +X L2 , X LCL =X L2 +X C2 +X LT , X L1 、X L2 、X C1 、X C2 、X C3 Represents the equivalent impedance of each component, X M Represents the equivalent impedance of the mutual inductance between the coils, R1 is the transmitting coil L T Internal resistance, R2 is the receiving coil L R Internal resistance, R is the equivalent resistance of the simplified battery charging circuit. I1-I5 represent Figure 2 The currents flowing through each circuit mesh in (a) and (b) can be solved as follows:

[0053]

[0054] For ease of analysis, the transconductance gain G is defined as the output current I O With input voltage U I According to formula (2), the transconductance gain G(ω CC ) and the voltage gain E(ω in CV mode CV ) can be expressed as:

[0055]

[0056] To realize CC mode and CV mode charging, G(ω CC ) and E(ω CV ) should be independent of R. Combining formula (3), it is not difficult to find that for CC mode, when X T = 0, G(ω CC ) has nothing to do with R; for CV mode, when (X VCL X LCL -X L2 2 )(X C3 +X LR )-X VCL X M 2 = 0, E(ω CV ) is independent of R. To reduce reactive input and improve system efficiency, the system needs to implement ZPA operation. The input impedance of the system in CC mode and CV mode can be expressed as follows:

[0057]

[0058] To achieve ZPA operation, the input resistance of the system should be purely resistive. T = 0, Z CC Purely resistive, in CV mode, X LCL = 0, ZCV is purely resistive. Therefore, to achieve ZPA in CC mode and CV mode, the resonance conditions must be met as follows:

[0059]

[0060] Where, ω represents the system operating angular frequency;

[0061] Optionally, the parameter configuration scheme of the present invention is as follows:

[0062] Substituting formula (5) into formula (2) can simplify the expression of each grid current to the following formula:

[0063]

[0064] In practical applications, the internal resistance of the coil is too small to be considered. The voltage across C2 can be expressed as:

[0065]

[0066] From the above formula, we can see that in CC mode, the voltage across C2 will gradually increase as the equivalent resistance of the battery charging circuit increases. To switch from CC mode to CV mode by changing the voltage across C2, when the equivalent resistance of the battery charging circuit reaches the switching resistance R switch When , the effective value of the voltage across C2 is equal in CC mode and CV mode, that is:

[0067]

[0068] Can be obtained:

[0069]

[0070] When the above equation is true, the effective value of the voltage across the battery charging circuit is always equal in both modes, as shown in the following equation:

[0071]

[0072] Substituting formula (5) into formula (7), the solutions of each element of the resonant network can be obtained as follows:

[0073]

[0074] Optionally, the trigger circuit is connected in parallel across the second compensation capacitor C2, and the voltage change of the second compensation capacitor C2 is the trigger condition of the trigger circuit; the AC / DC converter circuit and the first filter capacitor C f The first voltage divider resistor R is connected in parallel with the second compensation capacitor C2 to convert the AC power at both ends of C2 into DC power and input it into the hysteresis circuit; Div1 With the second voltage divider resistor R Div2 connected in series, the whole and the first compensation capacitor C f connected in parallel, used to divide the larger DC voltage into a lower voltage and input it into the hysteresis circuit; the first hysteresis circuit resistor R hc1 , the second hysteresis circuit resistor R hc2 The hysteresis circuit is composed of a hysteresis comparator and the whole circuit is connected with R Div2 Connect in parallel to determine R Div2 Whether the voltage across the terminals exceeds the reference voltage V REF , thereby controlling the output level state switching; the output voltage V switch Connected to the first signal relay KV1 and the second signal relay KV2, used as a trigger signal for the signal relay;

[0075] Substituting the values ​​of L2 and C2 into formula (3) yields the switching voltage U across C2: do for:

[0076]

[0077] Switching voltage U do This is the trigger voltage of the trigger circuit.

[0078] After the AC / DC converter circuit and resistor voltage division, the driving voltage U of the hysteresis circuit is Drive It can be calculated by the following formula:

[0079]

[0080] That is, when R Div2 The voltage across the two ends reaches U Drive When the hysteresis circuit is turned on, the hysteresis circuit reference value V REF Set to U Drive The values ​​are equal, V switch The output is high level, triggering signal relays KV1 and KV2 to close, realizing topology switching.

[0081] Example 2:

[0082] Based on the same inventive concept, Figure 3 As shown, the present invention provides a constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging method, comprising the following steps:

[0083] S1. Initialize the system. After the high-frequency full-bridge inverter circuit receives the PWM signal, the system enters the working state. At this time, the first signal relay KV1 and the second signal relay KV2 are in the disconnected state. The system forms an SS topology and is in CC mode.

[0084] S2. As the CC charging process continues, the charging current of the battery charging circuit remains unchanged, while the equivalent resistance of the battery charging circuit gradually increases, and the charging voltage of the battery charging circuit increases accordingly. Due to circuit characteristics, the voltage across the second compensation capacitor C2 also increases accordingly;

[0085] S3: When the charging voltage of the battery charging circuit reaches the maximum charging voltage U B When the voltage across C2 rises to the switching voltage U do , U do After rectification and voltage division, R Div2 The hysteresis circuit driving voltage formed by the voltage at both ends is also boosted to the hysteresis circuit reference value V REF , triggering the hysteresis circuit to switch the output state and output a high level V switch , the first signal relay KV1 and the second signal relay KV2 are activated; the conduction of KV1 and KV2 short-circuits the first compensation inductor L1 and connects the second compensation inductor L2 to the circuit. At this time, the system topology switches to CLC-S and is in CV mode;

[0086] S4: As the equivalent resistance of the battery charging circuit continues to increase, the charging voltage is maintained at UB The charging current of the battery charging circuit continues to decrease, the equivalent resistance of the battery charging circuit increases, the voltage across C2 remains unchanged, and the hysteresis circuit continues to conduct. When the charging current of the battery charging circuit drops to one tenth of the charging current in CC mode, charging stops.

[0087] In order to verify the rationality of the theory of the present invention, a corresponding model was established in the finite element simulation software for simulation verification. The simulation parameters are shown in Table 1.

[0088] Table 1 System simulation parameters

[0089]

[0090] In the table, f is the system operating frequency, R min is the minimum equivalent resistance of the battery charging circuit, R max is the maximum equivalent resistance of the battery charging circuit. CC mode transconductance gain G(ω CC ), CV mode voltage gain E(ω CV ) and the corresponding input impedance angle curve is as follows Figure 4 When the frequency reaches the system setting value of 85kHz, a constant G(ω) can be achieved for variable loads. CC ), E(ω CV ) and ZPA operations.

[0091] In order to verify the authenticity of the above theories and simulations, a Figure 5 The experimental prototype is shown in Table 2.

[0092] Table 2 Experimental prototype parameters

[0093]

[0094] The input voltage U is recorded under different load conditions using a Tektronix MSO54 oscilloscope. IN 、Input current I IN , output voltage U out , output current I out 、C2 voltage U C2 The waveform is as Figure 6 As shown in (a), (b), (c) and (d).

[0095] exist Figure 5In the experimental prototype shown, the CC mode of the system is characterized by the SS topology, providing a constant current charging state for the battery charging circuit, and the CV mode is characterized by the CLC-S topology, providing a constant voltage charging state for the battery charging circuit. When the load conditions are set to R = 25Ω, R = 35Ω, R = 45Ω, and R = 50Ω, they correspond to CC mode, CC mode, CV mode, and CV mode respectively. Figure 6 As shown in (a), (b), (c), and (d), when the system is in CC mode and no state switching occurs, as the equivalent resistance increases, I IN 、U out 、U C2 Both continue to increase, I out When the equivalent resistance of the battery charging circuit reaches the switching point resistance and continues to increase, the system switches to CV mode, U C2 with U out Remain unchanged, I IN with I out In order to more clearly and intuitively reflect the changes in the system electrical parameters, U out , I out 、U C2 、U Drive The continuous waveform under different load conditions is as follows Figure 7 shown.

[0096] Figure 7 The charging voltage U of the battery charging circuit is given when the equivalent resistance R of the simplified battery charging circuit is 25Ω, 35Ω, 45Ω, and 50Ω. out , charging current I out 、The voltage across C2 is U C2 , hysteresis circuit driving voltage U Drive When R is less than the switching point resistance, I out It will not change with the increase of resistance, U C2 with U Drive Continues to increase; when R is greater than the switching point resistance, I out The clamping is terminated and begins to gradually decrease, U out It will not change with the increase of resistance, U C2 with U Drive Stable at the on-state value.

[0097] Figure 8 The CC / CV charging curve and charging efficiency changes of the system designed by the present invention show that as the resistance increases, the charging efficiency decreases slightly and basically stabilizes at 92%. After switching to the CV state, the efficiency decreases faster, but it can still maintain a high charging efficiency.

[0098] This design method can take into account the system's CC mode and CV mode output characteristics as well as the overall transmission efficiency, and has higher use value;

[0099] The same or similar reference numerals correspond to the same or similar components;

[0100] The positional relationships described in the drawings are for illustrative purposes only and are not to be construed as limiting the present invention.

[0101] Obviously, the above examples of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging system, characterized in that: It includes a power supply circuit, a resonant coupling circuit, a trigger circuit and a battery charging circuit, wherein the resonant coupling circuit includes a transmitting end and a receiving end, and the transmitting end includes a transmitting coil L T , a first compensation inductor L1, a second compensation inductor L2, a first compensation capacitor C1, a second compensation capacitor C2, a first signal relay KV1 and a second signal relay KV2; the receiving end includes a receiving coil L R and the third compensation capacitor C3, where the transmitting coil L T With the receiving coil L R Mutual inductance coupling; when the transmitting end and the receiving end are in series-series (SS) compensation topology, the first signal relay KV1 and the second signal relay KV2 are disconnected, the first compensation inductor L1, the first compensation capacitor C1, the second compensation capacitor C2 and the transmitting coil L T Series connection, receiving coil L R The resonant coupling circuit is connected in series with the third compensation capacitor C3, and operates in constant current (CC) mode to provide a constant charging current for the battery charging circuit; when the transmitting end and the receiving end are CLC-series (CLC-S) compensation topology, the first signal relay KV1 and the second signal relay KV2 are turned on, and the second compensation capacitor C2 is connected to the transmitting coil L T The first compensation inductor C1 is connected in series with the receiving coil L2. R Connected in series with the third compensation capacitor C3, the resonant coupling circuit operates in constant voltage (CV) mode to provide a constant charging voltage for the battery charging circuit; the resonant coupling circuit provides trigger conditions for the trigger circuit, and the output voltage of the trigger circuit is used as a switching trigger signal for the resonant coupling circuit to operate in constant current (CC) mode and constant voltage (CV) mode; the trigger circuit includes a rectifier and voltage divider circuit and a hysteresis circuit. The rectifier and voltage divider circuit converts the input trigger signal into AC-DC and steps down the voltage before inputting it into the hysteresis circuit. The output voltage of the hysteresis circuit serves as a signal for switching the operating mode of the resonant coupling circuit; the power supply circuit provides electrical energy for the entire system.

2. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 1, characterized in that: The trigger circuit is connected in parallel across the second compensation capacitor C2. The voltage change of the second compensation capacitor C2 is a trigger condition of the trigger circuit. The trigger circuit output is used as a trigger signal for the first signal relay KV1 and the second signal relay KV2.

3. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 1, characterized in that: The rectifier and voltage divider circuit includes an AC / DC voltage conversion circuit, a first filter capacitor C f , the first voltage divider resistor R Div1 and the second voltage divider resistor R Div2 , the first filter capacitor C f In parallel with the AC / DC converter circuit, the first voltage divider resistor R Div1 With the second voltage divider resistor R Div2 After connecting in series with the first compensation capacitor C f Connect in parallel, the second voltage divider resistor R Div2 The voltage divider is input to the hysteresis circuit.

4. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 3, characterized in that: Hysteresis circuit and the second voltage divider resistor R Div2 Connected in parallel to determine the second voltage divider resistor R Div2 Whether the voltage across the terminals exceeds the reference voltage V REF , to control the output state of the hysteresis circuit; when the second voltage divider resistor R Div2 The voltage across the terminals exceeds the reference voltage V REF When the hysteresis circuit outputs a high level, the first signal relay KV1 and the second signal relay KV2 in the resonant coupling circuit are actuated to switch the state of the resonant coupling circuit; when the second voltage divider resistor R Div2 The voltage across the terminals does not exceed the reference voltage V REF When , the hysteresis circuit outputs a low level, the first signal relay KV1 and the second signal relay KV2 in the resonant coupling circuit do not trigger an action, and the state of the resonant coupling circuit does not switch.

5. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 1, characterized in that: The resonance condition of the resonant coupling circuit is: Where ω represents the system operating angular frequency, L1 is the first compensation inductor at the transmitter, L2 is the second compensation inductor at the transmitter, C1 is the first compensation capacitor at the transmitter, C2 is the second compensation capacitor at the transmitter, L T For the transmitting coil.

6. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 1, characterized in that: The parameter configuration scheme of each component in the resonant coupling circuit is: Where ω represents the system operating angular frequency, L1 is the first compensation inductor at the transmitter, L2 is the second compensation inductor at the transmitter, C1 is the first compensation capacitor at the transmitter, C2 is the second compensation capacitor at the transmitter, L T is the transmitting coil, R switch is the equivalent resistance value when the battery charging circuit switches from constant current (CC) mode to constant voltage (CV) mode, and M is the mutual inductance between the transmitting coil and the receiving coil.

7. The S / CLC-S type wireless charging system with constant current and constant voltage self-monitoring switching according to claim 1, characterized in that: The trigger conditions of the trigger circuit are: Among them, U do is the switching voltage, V i is the AC input voltage of the system, L T is the self-inductance of the transmitting coil, R switch is the equivalent resistance value when the battery charging circuit switches from constant current (CC) mode to constant voltage (CV) mode, ω represents the system operating angular frequency, M is the mutual inductance between the transmitting coil and the receiving coil; U Drive is the driving voltage of the hysteresis circuit, R Div1 is the first voltage divider resistor, R Div2 The second voltage divider resistor R Div2 ; When the voltage input from the resonant coupling circuit to the trigger circuit reaches U do When the second voltage divider resistor R Div2 The voltage across the two ends rises to the driving voltage U of the hysteresis circuit Drive , triggering the hysteresis circuit to output a high-level voltage, realizing the switching of the working mode of the resonant coupling circuit.

8. A constant current and constant voltage self-monitoring switching S / CLC-S type wireless charging method, characterized in that: The method adopts the system according to any one of claims 1 to 7, comprising the following steps: The system is initialized upon power-up and enters the working state. The resonant coupling circuit adopts the series-series (SS) compensation topology and is in the constant current (CC) mode. As the constant current (CC) mode charging process continues, the charging current of the battery charging circuit remains unchanged, while the equivalent internal resistance gradually increases, and the charging voltage of the battery charging circuit increases accordingly. Due to the circuit characteristics, the voltage input from the transmitter to the trigger circuit also increases accordingly. When the charging voltage of the battery charging circuit reaches the maximum charging voltage U B When the voltage input from the transmitter to the trigger circuit rises to the switching voltage U do , and then the hysteresis circuit driving voltage also increases to the hysteresis circuit reference value V REF , triggering the hysteresis circuit to switch the output state and output a high level V switch , controlling the resonant coupling circuit to switch to CLC-series (CLC-S) compensation topology, and then to constant voltage (CV) mode; As the equivalent resistance of the battery charging circuit continues to increase, the charging voltage is maintained at U B The charging current of the battery charging circuit continues to decrease. When it drops to one tenth of the constant current (CC) mode charging current, charging stops.

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